[LTP] [PATCH 0/3] Add support for kconfig constraints

[LTP] [PATCH 0/3] Add support for kconfig constraints

[Cyril Hrubis]

This patchset adds a support for generic boolean expressions in order to
be able to check for a more complex kernel configurations.

The motivation for this is recent rename in kernel config names that
cannot be checked for by a simplistic approach we previously
implemented.

The boolean expression parser was written as a generic as possible since
I do expect that we will reuse it for different types of assertions in
the future.

Cyril Hrubis (3):
  lib/tst_kconfig: Rewrite the parser internals
  lib: Add generic boolean expression parser and eval
  lib/tst_kconfig: Make use of boolean expression eval

 doc/test-writing-guidelines.txt  |  21 +-
 include/tst_bool_expr.h          |  80 +++++
 include/tst_kconfig.h            |  34 ++-
 lib/newlib_tests/.gitignore      |   1 +
 lib/newlib_tests/test_kconfig.c  |   1 +
 lib/newlib_tests/tst_bool_expr.c | 127 ++++++++
 lib/tst_bool_expr.c              | 504 +++++++++++++++++++++++++++++++
 lib/tst_kconfig.c                | 310 ++++++++++++-------
 8 files changed, 939 insertions(+), 139 deletions(-)
 create mode 100644 include/tst_bool_expr.h
 create mode 100644 lib/newlib_tests/tst_bool_expr.c
 create mode 100644 lib/tst_bool_expr.c

-- 
2.26.2

[LTP] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Cyril Hrubis]

This patch changes the parser internals so that the parser results are
not tied to the kconfigs array from the tst_test structure anymore.

This is a first step to a parser that can parse more complex
expressions.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 include/tst_kconfig.h |  34 ++++----
 lib/tst_kconfig.c     | 184 +++++++++++++++++++-----------------------
 2 files changed, 103 insertions(+), 115 deletions(-)

diff --git a/include/tst_kconfig.h b/include/tst_kconfig.h
index 2d2cfd782..1bb21fea8 100644
--- a/include/tst_kconfig.h
+++ b/include/tst_kconfig.h
@@ -6,27 +6,27 @@
 #ifndef TST_KCONFIG_H__
 #define TST_KCONFIG_H__
 
-struct tst_kconfig_res {
-	char match;
-	char *value;
+struct tst_kconfig_var {
+	char id[64];
+	unsigned int id_len;
+	char choice;
+	char *val;
 };
 
 /**
- * Reads a kernel config and parses it for values defined in kconfigs array.
+ *
+ * Reads a kernel config, parses it and writes results into an array of
+ * tst_kconfig_var structures.
  *
  * The path to the kernel config should be autodetected in most of the cases as
  * the code looks for know locations. It can be explicitely set/overrided with
  * the KCONFIG_PATH environment variable as well.
  *
- * The kcofings array is expected to contain strings in a format "CONFIG_FOO"
- * or "CONFIG_FOO=bar". The result array has to be suitably sized to fit the
- * results.
- *
- * @param kconfigs array of config strings to look for
- * @param results array to store results to
- * @param cnt size of the arrays
+ * The caller has to initialize the tst_kconfig_var structure. The id has to be
+ * filled with config variable name such as 'CONFIG_FOO', the id_len should
+ * hold the id string length and the choice and val has to be zeroed.
  *
- * The match in the tst_kconfig_res structure is set as follows:
+ * After a call to this function each choice be set as follows:
  *
  *  'm' - config option set to m
  *  'y' - config option set to y
@@ -34,11 +34,13 @@ struct tst_kconfig_res {
  *  'n' - config option is not set
  *   0  - config option not found
  *
- * In the case that match is set to 'v' the value points to a newly allocated
- * string that holds the value.
+ * In the case that match is set to 'v' the val pointer points to a newly
+ * allocated string that holds the value.
+ *
+ * @param vars An array of caller initalized tst_kconfig_var structures.
+ * @param vars_len Length of the vars array.
  */
-void tst_kconfig_read(const char *const kconfigs[],
-		      struct tst_kconfig_res results[], size_t cnt);
+void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len);
 
 /**
  * Checks if required kernel configuration options are set in the kernel
diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
index d49187b6f..f80925cc9 100644
--- a/lib/tst_kconfig.c
+++ b/lib/tst_kconfig.c
@@ -84,15 +84,6 @@ static void close_kconfig(FILE *fp)
 		fclose(fp);
 }
 
-struct match {
-	/* match len, string length up to \0 or = */
-	size_t len;
-	/* if set part of conf string after = */
-	const char *val;
-	/* if set the config option was matched already */
-	int match;
-};
-
 static int is_set(const char *str, const char *val)
 {
 	size_t vlen = strlen(val);
@@ -114,96 +105,70 @@ static int is_set(const char *str, const char *val)
 	}
 }
 
-static inline int match(struct match *match, const char *conf,
-                        struct tst_kconfig_res *result, const char *line)
+static inline int kconfig_parse_line(const char *line,
+                                     struct tst_kconfig_var *vars,
+                                     unsigned int vars_len)
 {
-	if (match->match)
-		return 0;
+	unsigned int i;
 
-	const char *cfg = strstr(line, "CONFIG_");
+	for (i = 0; i < vars_len; i++) {
+		if (!strncmp(vars[i].id, line, vars[i].id_len)) {
+			const char *val = &line[vars[i].id_len];
+
+			switch (val[0]) {
+			case '=':
+				break;
+			case ' ':
+				if (is_set(val, "is not set")) {
+					vars[i].choice = 'n';
+					return 1;
+				}
+				return 1;
+			/* vars[i].id may be prefix to longer config var */
+			default:
+				return 0;
+			}
 
-	if (!cfg)
-		return 0;
+			if (is_set(val, "=y")) {
+				vars[i].choice = 'y';
+				return 1;
+			}
 
-	if (strncmp(cfg, conf, match->len))
-		return 0;
+			if (is_set(val, "=m")) {
+				vars[i].choice = 'm';
+				return 1;
+			}
 
-	const char *val = &cfg[match->len];
+			vars[i].choice = 'v';
+			vars[i].val = strndup(val+1, strlen(val)-2);
 
-	switch (cfg[match->len]) {
-	case '=':
-		break;
-	case ' ':
-		if (is_set(val, "is not set")) {
-			result->match = 'n';
-			goto match;
+			return 1;
 		}
-	/* fall through */
-	default:
-		return 0;
-	}
-
-	if (is_set(val, "=y")) {
-		result->match = 'y';
-		goto match;
 	}
 
-	if (is_set(val, "=m")) {
-		result->match = 'm';
-		goto match;
-	}
-
-	result->match = 'v';
-	result->value = strndup(val+1, strlen(val)-2);
-
-match:
-	match->match = 1;
-	return 1;
+	return 0;
 }
 
-void tst_kconfig_read(const char *const *kconfigs,
-                      struct tst_kconfig_res results[], size_t cnt)
+void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len)
 {
-	struct match matches[cnt];
-	FILE *fp;
-	unsigned int i, j;
-	char buf[1024];
-
-	for (i = 0; i < cnt; i++) {
-		const char *val = strchr(kconfigs[i], '=');
-
-		if (strncmp("CONFIG_", kconfigs[i], 7))
-			tst_brk(TBROK, "Invalid config string '%s'", kconfigs[i]);
+	char line[128];
+	unsigned int vars_found = 0;
 
-		matches[i].match = 0;
-		matches[i].len = strlen(kconfigs[i]);
-
-		if (val) {
-			matches[i].val = val + 1;
-			matches[i].len -= strlen(val);
-		}
-
-		results[i].match = 0;
-		results[i].value = NULL;
-	}
-
-	fp = open_kconfig();
+	FILE *fp = open_kconfig();
 	if (!fp)
 		tst_brk(TBROK, "Cannot parse kernel .config");
 
-	while (fgets(buf, sizeof(buf), fp)) {
-		for (i = 0; i < cnt; i++) {
-			if (match(&matches[i], kconfigs[i], &results[i], buf)) {
-				for (j = 0; j < cnt; j++) {
-					if (matches[j].match)
-						break;
-				}
+	while (fgets(line, sizeof(line), fp)) {
+		char *cfg = strstr(line, "CONFIG_");
 
-				if (j == cnt)
-					goto exit;
-			}
-		}
+		if (!cfg)
+			continue;
+
+		if (kconfig_parse_line(line, vars, vars_len))
+			vars_found++;
 
+		if (vars_found == vars_len)
+			goto exit;
 	}
 
 exit:
@@ -219,42 +184,63 @@ static size_t array_len(const char *const kconfigs[])
 	return i;
 }
 
-static int compare_res(struct tst_kconfig_res *res, const char *kconfig,
-                       char match, const char *val)
+static int compare_res(struct tst_kconfig_var *var, const char *kconfig,
+                       char choice, const char *val)
 {
-	if (res->match != match) {
-		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, res->match);
+	if (var->choice != choice) {
+		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, var->choice);
 		return 1;
 	}
 
-	if (match != 'v')
+	if (choice != 'v')
 		return 0;
 
-	if (strcmp(res->value, val)) {
-		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, res->value);
+	if (strcmp(var->val, val)) {
+		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, var->val);
 		return 1;
 	}
 
 	return 0;
 }
 
+static inline unsigned int get_len(const char* kconfig)
+{
+	char *sep = index(kconfig, '=');
+
+	if (!sep)
+		return strlen(kconfig);
+
+	return sep - kconfig;
+}
+
 void tst_kconfig_check(const char *const kconfigs[])
 {
-	size_t cnt = array_len(kconfigs);
-	struct tst_kconfig_res results[cnt];
+	size_t vars_cnt = array_len(kconfigs);
+	struct tst_kconfig_var vars[vars_cnt];
 	unsigned int i;
 	int abort_test = 0;
 
-	tst_kconfig_read(kconfigs, results, cnt);
+	memset(vars, 0, sizeof(*vars) * vars_cnt);
+
+	for (i = 0; i < vars_cnt; i++) {
+		vars[i].id_len = get_len(kconfigs[i]);
+
+		if (vars[i].id_len >= sizeof(vars[i].id))
+			tst_brk(TBROK, "kconfig var id too long!");
+
+		strncpy(vars[i].id, kconfigs[i], vars[i].id_len);
+	}
+
+	tst_kconfig_read(vars, vars_cnt);
 
-	for (i = 0; i < cnt; i++) {
-		if (results[i].match == 0) {
+	for (i = 0; i < vars_cnt; i++) {
+		if (vars[i].choice == 0) {
 			tst_res(TINFO, "Missing kernel %s", kconfigs[i]);
 			abort_test = 1;
 			continue;
 		}
 
-		if (results[i].match == 'n') {
+		if (vars[i].choice == 'n') {
 			tst_res(TINFO, "Kernel %s is not set", kconfigs[i]);
 			abort_test = 1;
 			continue;
@@ -263,21 +249,21 @@ void tst_kconfig_check(const char *const kconfigs[])
 		const char *val = strchr(kconfigs[i], '=');
 
 		if (val) {
-			char match = 'v';
+			char choice = 'v';
 			val++;
 
 			if (!strcmp(val, "y"))
-				match = 'y';
+				choice = 'y';
 
 			if (!strcmp(val, "m"))
-				match = 'm';
+				choice = 'm';
 
-			if (compare_res(&results[i], kconfigs[i], match, val))
+			if (compare_res(&vars[i], kconfigs[i], choice, val))
 				abort_test = 1;
 
 		}
 
-		free(results[i].value);
+		free(vars[i].val);
 	}
 
 	if (abort_test)
-- 
2.26.2

[LTP] [PATCH 2/3] lib: Add generic boolean expression parser and eval

[Cyril Hrubis]

Add a simple and generic boolean expression parser and evaluator. This
is a second step in order to implement more complex kconfig expressions,
but since we are likely to reuse the parser for other purposes in the
future it's implemented as a generic boolean parser.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 include/tst_bool_expr.h          |  80 +++++
 lib/newlib_tests/.gitignore      |   1 +
 lib/newlib_tests/tst_bool_expr.c | 127 ++++++++
 lib/tst_bool_expr.c              | 504 +++++++++++++++++++++++++++++++
 4 files changed, 712 insertions(+)
 create mode 100644 include/tst_bool_expr.h
 create mode 100644 lib/newlib_tests/tst_bool_expr.c
 create mode 100644 lib/tst_bool_expr.c

diff --git a/include/tst_bool_expr.h b/include/tst_bool_expr.h
new file mode 100644
index 000000000..e163690ab
--- /dev/null
+++ b/include/tst_bool_expr.h
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2020 Cyril Hrubis <chrubis@suse.cz>
+ */
+
+#ifndef TST_BOOL_EXPR_H__
+#define TST_BOOL_EXPR_H__
+
+enum tst_op {
+	TST_OP_NOT,
+	TST_OP_AND,
+	TST_OP_OR,
+	TST_OP_VAR,
+	/* Used only internally */
+	TST_OP_LPAR,
+	TST_OP_RPAR,
+};
+
+struct tst_expr {
+	enum tst_op op;
+	struct tst_expr *next;
+	char *err;
+	void *priv;
+	char val[];
+};
+
+/*
+ * Parses an boolean expression and returns a simplified RPN version.
+ *
+ * If expression is not valid the call prints error into stderr and returns
+ * NULL. On success pointer to an expression is returned which can be evaluated
+ * by the tst_bool_expr_eval() function and has to be later freed by the
+ * caller.
+ *
+ * The boolean expression can consists of:
+ *
+ * - unary negation opeartion !
+ * - two binary operations & and |
+ * - correct sequence of parentheses ()
+ * - strings that are treated as boolean variables
+ *
+ *  e.g. '(A | B) & C' or 'Variable_1 & Variable_2' are both a valid boolean
+ *  expressions.
+ *
+ *  @expr String containing a boolean expression to be parsed.
+ *  @return Pointer to an RPN expression.
+ */
+struct tst_expr *tst_bool_expr_parse(const char *expr);
+
+/*
+ * Prints an string representation of the expression into a FILE.
+ *
+ * @param A FILE to print to.
+ * @expr An expression to print.
+ */
+void tst_bool_expr_print(FILE *f, struct tst_expr *expr);
+
+/*
+ * Evaluates an expression given a map for variables.
+ *
+ * The call will fail if:
+ * - map function returns -1 which indicates undefined variable
+ * - the eval function runs out of stack
+ *
+ * @param expr Boolean expression in RPN.
+ * @param map Mapping function for boolean variables.
+ *
+ * @return Returns 0 or 1 if expression was evaluated correctly and -1 on error.
+ */
+int tst_bool_expr_eval(struct tst_expr *expr,
+                       int (*map)(struct tst_expr *var));
+
+/*
+ * Frees the memory allocated by the tst_bool_expr_parse().
+ *
+ * @param Boolean expression.
+ */
+void tst_bool_expr_free(struct tst_expr *expr);
+
+#endif	/* TST_BOOL_EXPR_H__ */
diff --git a/lib/newlib_tests/.gitignore b/lib/newlib_tests/.gitignore
index 44bc6526f..1e96db1da 100644
--- a/lib/newlib_tests/.gitignore
+++ b/lib/newlib_tests/.gitignore
@@ -33,3 +33,4 @@ test_exec_child
 test_kconfig
 variant
 test_guarded_buf
+tst_bool_expr
diff --git a/lib/newlib_tests/tst_bool_expr.c b/lib/newlib_tests/tst_bool_expr.c
new file mode 100644
index 000000000..5f5e618dc
--- /dev/null
+++ b/lib/newlib_tests/tst_bool_expr.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2017 Cyril Hrubis <chrubis@suse.cz>
+ */
+
+/*
+ * Basic unit test for the tst_strstatus() function.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include "tst_test.h"
+#include "tst_bool_expr.h"
+
+static int a, b, c;
+
+static int map(struct tst_expr *var)
+{
+	if (!strcmp(var->val, "A"))
+		return a;
+
+	if (!strcmp(var->val, "B"))
+		return b;
+
+	if (!strcmp(var->val, "C"))
+		return c;
+
+	if (!strcmp(var->val, "True"))
+		return 1;
+
+	if (!strcmp(var->val, "False"))
+		return 0;
+
+	return -1;
+}
+
+static void parse_fail(const char *expr)
+{
+	struct tst_expr *res;
+
+	tst_res(TINFO, "Parsing '%s'", expr);
+
+	res = tst_bool_expr_parse(expr);
+
+	if (res) {
+		printf("In RPN: ");
+		tst_bool_expr_print(stdout, res);
+		printf("\n");
+		tst_bool_expr_free(res);
+		tst_res(TFAIL, "Expression was parsed");
+	} else {
+		tst_res(TPASS, "Parser returned an error");
+	}
+}
+
+static void do_eval_test(const char *expr_str, int set_a, int set_b, int set_c, int exp_res)
+{
+	struct tst_expr *expr;
+	int res;
+
+	a = set_a;
+	b = set_b;
+	c = set_c;
+
+	tst_res(TINFO, "'%s' A=%i B=%i C=%i == %i", expr_str, a, b, c, exp_res);
+
+	expr = tst_bool_expr_parse(expr_str);
+
+	if (!expr) {
+		tst_res(TFAIL, "Parser returned error");
+		return;
+	}
+
+	printf("In RPN: ");
+	tst_bool_expr_print(stdout, expr);
+	printf("\n");
+
+	res = tst_bool_expr_eval(expr, map);
+
+	if (res == exp_res)
+		tst_res(TPASS, "Got %i", res);
+	else
+		tst_res(TFAIL, "Got %i", res);
+
+	tst_bool_expr_free(expr);
+}
+
+static void do_test(void)
+{
+	do_eval_test("(A | B) & !!C", 0, 0, 0, 0);
+	do_eval_test("(A | B) & !!C", 1, 0, 1, 1);
+	do_eval_test("!A & B", 1, 0, 0, 0);
+	do_eval_test("!A & B", 0, 1, 0, 1);
+	do_eval_test("A & !B", 1, 0, 0, 1);
+	do_eval_test("!!A & !!B", 0, 1, 0, 0);
+	do_eval_test("!!A & !!B", 1, 1, 0, 1);
+	do_eval_test("!(A & B) & C", 1, 1, 0, 0);
+	do_eval_test("A & (B | C)", 1, 1, 0, 1);
+	do_eval_test("((((A)))&(B))", 1, 1, 0, 1);
+	do_eval_test("True | A", 0, 0, 0, 1);
+	do_eval_test("False & A", 1, 0, 0, 0);
+	do_eval_test("! Undefined", 0, 0, 0, -1);
+
+	parse_fail("A!");
+	parse_fail("A &");
+	parse_fail("A B");
+	parse_fail("A ) B");
+	parse_fail("A ( B");
+	parse_fail("A ( B )");
+	parse_fail("A |");
+	parse_fail("A ! B");
+	parse_fail("A! & B");
+	parse_fail("A & | B");
+	parse_fail("A & (B |)");
+	parse_fail("A & ( | B)");
+	parse_fail("A & B &");
+	parse_fail("((A )");
+	parse_fail("& A");
+	parse_fail("! &");
+	parse_fail(")");
+	parse_fail("| A");
+	parse_fail("");
+}
+
+static struct tst_test test = {
+	.test_all = do_test,
+};
diff --git a/lib/tst_bool_expr.c b/lib/tst_bool_expr.c
new file mode 100644
index 000000000..3cb395664
--- /dev/null
+++ b/lib/tst_bool_expr.c
@@ -0,0 +1,504 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2020 Cyril Hrubis <chrubis@suse.cz>
+ */
+/*
+ * Boolean expression is evaluated in three steps.
+ *
+ * First of all the string containing the expression is tokenized.
+ *
+ * Secondly the the expression is transformed to a postfix (RPN) notation by
+ * the shunting yard algorithm and the correctness of the expression is checked
+ * during the transformation as well. The fact that parenthesis are matched is
+ * asserted by the shunting yard algorithm itself while the rest is checked
+ * simply by checking if the preceding token is in a set of allowed tokens.
+ * This could be thought of as a simple open-coded state machine.
+ *
+ * An expression in the RPN form can be evaluated given a variable mapping
+ * function. The evaluation ignores most of errors because invalid expression
+ * will be rejected in the second step.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "tst_bool_expr.h"
+
+#define MAX_TOK 1024
+
+struct tok {
+	unsigned int pos;
+	char buf[MAX_TOK];
+};
+
+static inline void tok_append(struct tok *tok, char c)
+{
+	if (tok->pos + 2 >= MAX_TOK) {
+		tok->buf[tok->pos+1] = 0;
+		fprintf(stderr, "Truncating token '%s'!", tok->buf);
+	}
+
+	tok->buf[tok->pos++] = c;
+}
+
+static inline char *tok_get(struct tok *tok)
+{
+	if (!tok->pos)
+		return NULL;
+
+	tok->buf[tok->pos] = '\0';
+
+	tok->pos = 0;
+
+	return tok->buf;
+}
+
+static struct tst_expr *new_var(const char *val)
+{
+	struct tst_expr *ret;
+
+	if (!val)
+		return NULL;
+
+	ret = malloc(sizeof(struct tst_expr) + strlen(val) + 1);
+	if (!ret)
+		return NULL;
+
+	ret->op = TST_OP_VAR;
+	ret->next = NULL;
+	ret->err = NULL;
+	strcpy(ret->val, val);
+
+	return ret;
+}
+
+enum tst_op char_to_op(char c)
+{
+	switch (c) {
+	case '(':
+		return TST_OP_LPAR;
+	case ')':
+		return TST_OP_RPAR;
+	case '&':
+		return TST_OP_AND;
+	case '|':
+		return TST_OP_OR;
+	case '!':
+		return TST_OP_NOT;
+	default:
+		return -1;
+	}
+}
+
+static struct tst_expr *new_op(char c)
+{
+	struct tst_expr *ret;
+
+	ret = malloc(sizeof(struct tst_expr));
+	if (!ret)
+		return NULL;
+
+	ret->op = char_to_op(c);
+	ret->next = NULL;
+	ret->err = NULL;
+
+	return ret;
+}
+
+struct op_list {
+	struct tst_expr *first;
+	struct tst_expr *last;
+	unsigned int cnt;
+};
+
+static void op_list_append(struct op_list *list, struct tst_expr *val)
+{
+	if (!val)
+		return;
+
+	if (!list->first)
+		list->first = val;
+
+	if (list->last)
+		list->last->next = val;
+
+	list->last = val;
+
+	list->cnt++;
+}
+
+static void tokenize(const char *expr, struct op_list *ret)
+{
+	struct tok buf = {};
+	size_t i;
+
+	for (i = 0; expr[i]; i++) {
+		switch (expr[i]) {
+		case '(':
+		case ')':
+		case '!':
+		case '&':
+		case '|':
+			op_list_append(ret, new_var(tok_get(&buf)));
+			op_list_append(ret, new_op(expr[i]));
+		break;
+		case '\t':
+		case ' ':
+			op_list_append(ret, new_var(tok_get(&buf)));
+		break;
+		default:
+			tok_append(&buf, expr[i]);
+		break;
+		}
+	}
+
+	op_list_append(ret, new_var(tok_get(&buf)));
+}
+
+void tst_bool_expr_print(FILE *f, struct tst_expr *expr)
+{
+	struct tst_expr *i;
+	int prev_op = 0;
+
+	for (i = expr; i; i = i->next) {
+		if (i->op != TST_OP_VAR && prev_op)
+			fprintf(f, " ");
+
+		switch (i->op) {
+		case TST_OP_AND:
+			fprintf(f, "&");
+		break;
+		case TST_OP_OR:
+			fprintf(f, "|");
+		break;
+		case TST_OP_NOT:
+			fprintf(f, "!");
+		break;
+		case TST_OP_LPAR:
+			fprintf(f, "(");
+		break;
+		case TST_OP_RPAR:
+			fprintf(f, ")");
+		break;
+		case TST_OP_VAR:
+			fprintf(f, " %s ", i->val);
+		break;
+		}
+
+		if (i->op == TST_OP_VAR)
+			prev_op = 0;
+		else
+			prev_op = 1;
+	}
+}
+
+static void tst_bool_expr_err(FILE *f, struct tst_expr *expr)
+{
+	struct tst_expr *i;
+	int prev_op = 0;
+	unsigned int spaces = 0;
+
+	fprintf(f, "\n");
+
+	for (i = expr; i; i = i->next) {
+		if (i->err)
+			break;
+
+		if (i->op != TST_OP_VAR && prev_op)
+			spaces++;
+
+		switch (i->op) {
+		case TST_OP_VAR:
+			spaces += 2 + strlen(i->val);
+		break;
+		default:
+			spaces++;
+		}
+
+		if (i->op == TST_OP_VAR)
+			prev_op = 0;
+		else
+			prev_op = 1;
+	}
+
+	while (spaces--)
+		putc(' ', f);
+
+	fprintf(f, "^\n");
+	fprintf(f, "%s\n", i->err);
+}
+
+static inline void stack_push(struct tst_expr *stack[], unsigned int *stack_pos,
+                              struct tst_expr *op)
+{
+	stack[(*stack_pos)++] = op;
+}
+
+static inline int stack_empty(unsigned int stack_pos)
+{
+	return stack_pos == 0;
+}
+
+static inline struct tst_expr *stack_pop(struct tst_expr *stack[],
+                                          unsigned int *stack_pos)
+{
+	if (stack_empty(*stack_pos))
+		return NULL;
+
+	return stack[--(*stack_pos)];
+}
+
+static inline enum tst_op stack_top_op(struct tst_expr *stack[],
+                                       unsigned int stack_pos)
+{
+	if (stack_empty(stack_pos))
+		return -1;
+
+	return stack[stack_pos - 1]->op;
+}
+
+/*
+ * This is a complete list of which tokens can happen before any of:
+ *  - variable
+ *  - left parentesis
+ *  - negation
+ *
+ * The -1 represents start of the expression.
+ */
+static inline int check_one(int op)
+{
+	switch (op) {
+	case TST_OP_AND:
+	case TST_OP_OR:
+	case TST_OP_NOT:
+	case -1:
+	case TST_OP_LPAR:
+		return 0;
+	default:
+		return 1;
+	}
+}
+
+/*
+ * And this checks for tokens that can happen before any of:
+ * - right parentesis
+ * - and
+ * - or
+ *
+ * This is also used to check that the last token in expression is correct one.
+ */
+static inline int check_two(int op)
+{
+	switch (op) {
+	case TST_OP_VAR:
+	case TST_OP_RPAR:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+static struct tst_expr *shunting_yard(struct op_list *list)
+{
+	struct tst_expr *stack[list->cnt];
+	unsigned int stack_pos = 0;
+	struct tst_expr *out[list->cnt + 1];
+	unsigned int out_pos = 0;
+	struct tst_expr *pars[list->cnt];
+	unsigned int pars_pos = 0;
+	struct tst_expr *i;
+	unsigned int j;
+	int prev_op = -1;
+
+	for (i = list->first; i; i = i->next) {
+		switch (i->op) {
+		case TST_OP_VAR:
+			if (check_one(prev_op) && prev_op != TST_OP_LPAR) {
+				i->err = "Expected operation";
+				goto err;
+			}
+
+			stack_push(out, &out_pos, i);
+
+			/* pop all negations */
+			while (stack_top_op(stack, stack_pos) == TST_OP_NOT)
+				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
+		break;
+		case TST_OP_LPAR:
+			if (check_one(prev_op)) {
+				i->err = "Expected operation";
+				goto err;
+			}
+
+			stack_push(stack, &stack_pos, i);
+		break;
+		case TST_OP_RPAR:
+			if (!check_two(prev_op)) {
+				i->err = "Expected variable or )";
+				goto err;
+			}
+
+			stack_push(pars, &pars_pos, i);
+
+			/* pop everything till ( */
+			for (;;) {
+				struct tst_expr *op = stack_pop(stack, &stack_pos);
+
+				if (!op) {
+					i->err = "Missing (";
+					goto err;
+				}
+
+				if (op->op == TST_OP_LPAR) {
+					stack_push(pars, &pars_pos, op);
+					break;
+				}
+
+				stack_push(out, &out_pos, op);
+			}
+
+			/* pop all negations */
+			while (stack_top_op(stack, stack_pos) == TST_OP_NOT)
+				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
+		break;
+		case TST_OP_NOT:
+			if (check_one(prev_op)) {
+				i->err = "Expected operation";
+				goto err;
+			}
+			stack_push(stack, &stack_pos, i);
+		break;
+		case TST_OP_AND:
+		case TST_OP_OR:
+			if (!check_two(prev_op)) {
+				i->err = "Expected variable or (";
+				goto err;
+			}
+
+			/* pop all binary ops */
+			for (;;) {
+				enum tst_op top_op;
+
+				if (stack_empty(stack_pos))
+					break;
+
+				top_op = stack_top_op(stack, stack_pos);
+
+				if (top_op == TST_OP_LPAR ||
+				    top_op == TST_OP_NOT)
+					break;
+
+				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
+			}
+			stack_push(stack, &stack_pos, i);
+		break;
+		}
+
+		prev_op = i->op;
+	}
+
+	if (!check_two(list->last->op)) {
+		list->last->err = "Unfinished expression";
+		goto err;
+	}
+
+	/* pop remaining operations */
+	while ((i = stack_pop(stack, &stack_pos))) {
+		if (i->op == TST_OP_LPAR) {
+			i->err = "Missing )";
+			goto err;
+		}
+
+		stack_push(out, &out_pos, i);
+	}
+
+	/* free parentesis */
+	for (j = 0; j < pars_pos; j++)
+		free(pars[j]);
+
+	/* reconstruct the list */
+	out[out_pos] = NULL;
+
+	for (j = 0; j < out_pos; j++)
+		out[j]->next = out[j + 1];
+
+	return out[0];
+err:
+	return NULL;
+}
+
+struct tst_expr *tst_bool_expr_parse(const char *expr)
+{
+	struct op_list list = {};
+	struct tst_expr *ret;
+
+	tokenize(expr, &list);
+
+	if (!list.first)
+		return NULL;
+
+	ret = shunting_yard(&list);
+
+	if (!ret) {
+		tst_bool_expr_print(stderr, list.first);
+		tst_bool_expr_err(stderr, list.first);
+		tst_bool_expr_free(list.first);
+		return NULL;
+	}
+
+	return ret;
+}
+
+#define MAX_STACK 16
+
+int tst_bool_expr_eval(struct tst_expr *expr,
+                       int (*map)(struct tst_expr *var))
+{
+	struct tst_expr *i;
+	int stack[MAX_STACK];
+	int pos = -1;
+
+	for (i = expr; i; i = i->next) {
+		switch (i->op) {
+		case TST_OP_NOT:
+			stack[pos] = !stack[pos];
+		break;
+		case TST_OP_OR:
+			stack[pos-1] = stack[pos] || stack[pos-1];
+			pos--;
+		break;
+		case TST_OP_AND:
+			stack[pos-1] = stack[pos] && stack[pos-1];
+			pos--;
+		break;
+		case TST_OP_VAR:
+			if (pos + 1 >= MAX_STACK) {
+				fprintf(stderr, "Eval out of stack!\n");
+				return -1;
+			}
+
+			stack[++pos] = map(i);
+
+			/* map reported undefined variable -> abort */
+			if (stack[pos] == -1)
+				return -1;
+		break;
+		/* does not happen */
+		default:
+		break;
+		}
+	}
+
+	return stack[0];
+}
+
+void tst_bool_expr_free(struct tst_expr *expr)
+{
+	struct tst_expr *i = expr, *tmp;
+
+	while (i) {
+		tmp = i;
+		i = i->next;
+		free(tmp);
+	}
+}
-- 
2.26.2

[LTP] [PATCH 3/3] lib/tst_kconfig: Make use of boolean expression eval

[Cyril Hrubis]

Now each string in the kconfig[] array in tst_test structure is an
boolean expression which is evaluated. All expressions has to be true in
order for the test to continue.

+ Update the docs.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
CC: Pengfei Xu <pengfei.xu@intel.com>
---
 doc/test-writing-guidelines.txt |  21 ++--
 lib/newlib_tests/test_kconfig.c |   1 +
 lib/tst_kconfig.c               | 186 ++++++++++++++++++++++++--------
 3 files changed, 154 insertions(+), 54 deletions(-)

diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
index 1a51ef7c7..3c2ab7166 100644
--- a/doc/test-writing-guidelines.txt
+++ b/doc/test-writing-guidelines.txt
@@ -1643,21 +1643,26 @@ on the system, disabled syscalls can be detected by checking for 'ENOSYS'
 errno etc.
 
 However in rare cases core kernel features couldn't be detected based on the
-kernel userspace API and we have to resort to kernel .config parsing.
+kernel userspace API and we have to resort to parse the kernel .config.
 
-For this cases the test should set the 'NULL' terminated '.needs_kconfigs' array
-of kernel config options required for the test. The config option can be
-specified either as plain "CONFIG_FOO" in which case it's sufficient for the
-test continue if it's set to any value (typically =y or =m). Or with a value
-as "CONFIG_FOO=bar" in which case the value has to match as well. The test is
-aborted with 'TCONF' if any of the required options were not set.
+For this cases the test should set the 'NULL' terminated '.needs_kconfigs'
+array of boolean expressions with constraints on the kconfig variables. The
+boolean expression consits of variables, two binary operations '&' and '|',
+negation '!' and correct sequence of parentesis '()'. Variables are expected
+to be in a form of "CONFIG_FOO[=bar]".
+
+The test will continue to run if all expressions are evaluated to 'True'.
+Missing variable is mapped to 'False' as well as variable with different than
+specified value, e.g. 'CONFIG_FOO=bar' will evaluate to 'False' if the value
+is anything else but 'bar'. If config variable is specified as plain
+'CONFIG_FOO' it's evaluated to true it's set to any value (typically =y or =m).
 
 [source,c]
 -------------------------------------------------------------------------------
 #include "tst_test.h"
 
 static const char *kconfigs[] = {
-	"CONFIG_X86_INTEL_UMIP",
+	"CONFIG_X86_INTEL_UMIP | CONFIG_X86_UMIP",
 	NULL
 };
 
diff --git a/lib/newlib_tests/test_kconfig.c b/lib/newlib_tests/test_kconfig.c
index d9c662fc5..183d55611 100644
--- a/lib/newlib_tests/test_kconfig.c
+++ b/lib/newlib_tests/test_kconfig.c
@@ -14,6 +14,7 @@ static const char *kconfigs[] = {
 	"CONFIG_MMU",
 	"CONFIG_EXT4_FS=m",
 	"CONFIG_PGTABLE_LEVELS=4",
+	"CONFIG_MMU & CONFIG_EXT4_FS=m",
 	NULL
 };
 
diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
index f80925cc9..cd99a3034 100644
--- a/lib/tst_kconfig.c
+++ b/lib/tst_kconfig.c
@@ -12,6 +12,7 @@
 #define TST_NO_DEFAULT_MAIN
 #include "tst_test.h"
 #include "tst_kconfig.h"
+#include "tst_bool_expr.h"
 
 static const char *kconfig_path(char *path_buf, size_t path_buf_len)
 {
@@ -184,86 +185,179 @@ static size_t array_len(const char *const kconfigs[])
 	return i;
 }
 
-static int compare_res(struct tst_kconfig_var *var, const char *kconfig,
-                       char choice, const char *val)
+static inline unsigned int get_len(const char* kconfig)
 {
-	if (var->choice != choice) {
-		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, var->choice);
-		return 1;
-	}
+	char *sep = index(kconfig, '=');
 
-	if (choice != 'v')
-		return 0;
+	if (!sep)
+		return strlen(kconfig);
 
-	if (strcmp(var->val, val)) {
-		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, var->val);
-		return 1;
+	return sep - kconfig;
+}
+
+static inline unsigned int get_var_cnt(struct tst_expr *exprs[],
+                                       unsigned int expr_cnt)
+{
+	unsigned int i;
+	struct tst_expr *j;
+	unsigned int cnt = 0;
+
+	for (i = 0; i < expr_cnt; i++) {
+		for (j = exprs[i]; j; j = j->next) {
+			if (j->op == TST_OP_VAR)
+				cnt++;
+		}
 	}
 
-	return 0;
+	return cnt;
 }
 
-static inline unsigned int get_len(const char* kconfig)
+static struct tst_kconfig_var *find_var(struct tst_kconfig_var vars[],
+                                        unsigned int var_cnt,
+                                        const char *var)
 {
-	char *sep = index(kconfig, '=');
+	unsigned int i;
 
-	if (!sep)
-		return strlen(kconfig);
+	for (i = 0; i < var_cnt; i++) {
+		if (!strcmp(vars[i].id, var))
+			return &vars[i];
+	}
 
-	return sep - kconfig;
+	return NULL;
 }
 
-void tst_kconfig_check(const char *const kconfigs[])
+/*
+ * Fill in the kconfig variables array from the expressions. Also makes sure
+ * that each variable is copied to the array exaclty once.
+ */
+static inline unsigned int get_vars(struct tst_expr *exprs[],
+                                    unsigned int expr_cnt,
+                                    struct tst_kconfig_var vars[])
 {
-	size_t vars_cnt = array_len(kconfigs);
-	struct tst_kconfig_var vars[vars_cnt];
 	unsigned int i;
-	int abort_test = 0;
+	struct tst_expr *j;
+	unsigned int cnt = 0;
+
+	for (i = 0; i < expr_cnt; i++) {
+		for (j = exprs[i]; j; j = j->next) {
+			struct tst_kconfig_var *var;
 
-	memset(vars, 0, sizeof(*vars) * vars_cnt);
+			if (j->op != TST_OP_VAR)
+				continue;
 
-	for (i = 0; i < vars_cnt; i++) {
-		vars[i].id_len = get_len(kconfigs[i]);
+			vars[cnt].id_len = get_len(j->val);
 
-		if (vars[i].id_len >= sizeof(vars[i].id))
-			tst_brk(TBROK, "kconfig var id too long!");
+			if (vars[cnt].id_len >= sizeof(vars[cnt].id))
+				tst_brk(TBROK, "kconfig var id too long!");
 
-		strncpy(vars[i].id, kconfigs[i], vars[i].id_len);
+			strncpy(vars[cnt].id, j->val, vars[cnt].id_len);
+
+			var = find_var(vars, cnt, vars[cnt].id);
+
+			if (var)
+				j->priv = var;
+			else
+				j->priv = &vars[cnt++];
+		}
 	}
 
-	tst_kconfig_read(vars, vars_cnt);
+	return cnt;
+}
+
+static int map(struct tst_expr *expr)
+{
+	struct tst_kconfig_var *var = expr->priv;
 
-	for (i = 0; i < vars_cnt; i++) {
-		if (vars[i].choice == 0) {
-			tst_res(TINFO, "Missing kernel %s", kconfigs[i]);
-			abort_test = 1;
+	if (var->choice == 0)
+		return 0;
+
+	const char *val = strchr(expr->val, '=');
+
+	/* CONFIG_FOO evaluates to true if y or m */
+	if (!val)
+		return var->choice == 'y' || var->choice == 'm';
+
+	char choice = 'v';
+	val++;
+
+	if (!strcmp(val, "n"))
+		choice = 'n';
+
+	if (!strcmp(val, "y"))
+		choice = 'y';
+
+	if (!strcmp(val, "m"))
+		choice = 'm';
+
+	if (choice != 'v')
+		return var->choice == choice;
+
+	return !strcmp(val, var->val);
+}
+
+static void dump_vars(struct tst_expr *expr)
+{
+	struct tst_expr *i;
+	struct tst_kconfig_var *var;
+
+	tst_res(TINFO, "Variables:");
+
+	for (i = expr; i; i = i->next) {
+		if (i->op != TST_OP_VAR)
+			continue;
+
+		var = i->priv;
+
+		if (!var->choice) {
+			tst_res(TINFO, "%s Undefined", var->id);
 			continue;
 		}
 
-		if (vars[i].choice == 'n') {
-			tst_res(TINFO, "Kernel %s is not set", kconfigs[i]);
-			abort_test = 1;
+		if (var->choice == 'v') {
+			tst_res(TINFO, "%s = %s", var->id, var->val);
 			continue;
 		}
 
-		const char *val = strchr(kconfigs[i], '=');
+		tst_res(TINFO, "%s = %c", var->id, var->choice);
+	}
+}
 
-		if (val) {
-			char choice = 'v';
-			val++;
+void tst_kconfig_check(const char *const kconfigs[])
+{
+	size_t expr_cnt = array_len(kconfigs);
+	struct tst_expr *exprs[expr_cnt];
+	unsigned int i, var_cnt;
+	int abort_test = 0;
+
+	for (i = 0; i < expr_cnt; i++) {
+		exprs[i] = tst_bool_expr_parse(kconfigs[i]);
+
+		if (!exprs[i])
+			tst_brk(TBROK, "Invalid kconfig expression!");
+	}
 
-			if (!strcmp(val, "y"))
-				choice = 'y';
+	var_cnt = get_var_cnt(exprs, expr_cnt);
+	struct tst_kconfig_var vars[var_cnt];
 
-			if (!strcmp(val, "m"))
-				choice = 'm';
+	var_cnt = get_vars(exprs, expr_cnt, vars);
 
-			if (compare_res(&vars[i], kconfigs[i], choice, val))
-				abort_test = 1;
+	tst_kconfig_read(vars, var_cnt);
 
+	for (i = 0; i < expr_cnt; i++) {
+		int val = tst_bool_expr_eval(exprs[i], map);
+
+		if (val != 1) {
+			abort_test = 1;
+			tst_res(TINFO, "Expression '%s' not satisfied!", kconfigs[i]);
+			dump_vars(exprs[i]);
 		}
 
-		free(vars[i].val);
+		tst_bool_expr_free(exprs[i]);
+	}
+
+	for (i = 0; i < var_cnt; i++) {
+		if (vars[i].choice == 'v')
+			free(vars[i].val);
 	}
 
 	if (abort_test)
-- 
2.26.2

[LTP] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Richard Palethorpe]

Hello,

Cyril Hrubis <chrubis@suse.cz> writes:

> This patch changes the parser internals so that the parser results are
> not tied to the kconfigs array from the tst_test structure anymore.
>
> This is a first step to a parser that can parse more complex
> expressions.
>
> Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
> ---
>  include/tst_kconfig.h |  34 ++++----
>  lib/tst_kconfig.c     | 184 +++++++++++++++++++-----------------------
>  2 files changed, 103 insertions(+), 115 deletions(-)
>
> diff --git a/include/tst_kconfig.h b/include/tst_kconfig.h
> index 2d2cfd782..1bb21fea8 100644
> --- a/include/tst_kconfig.h
> +++ b/include/tst_kconfig.h
> @@ -6,27 +6,27 @@
>  #ifndef TST_KCONFIG_H__
>  #define TST_KCONFIG_H__
>  
> -struct tst_kconfig_res {
> -	char match;
> -	char *value;
> +struct tst_kconfig_var {
> +	char id[64];
> +	unsigned int id_len;
> +	char choice;

This should probably be an enum to give the compiler more info. Even if
we use the current char values as the enum entries.

> +	char *val;
>  };
>  
>  /**
> - * Reads a kernel config and parses it for values defined in kconfigs array.
> + *
> + * Reads a kernel config, parses it and writes results into an array of
> + * tst_kconfig_var structures.
>   *
>   * The path to the kernel config should be autodetected in most of the cases as
>   * the code looks for know locations. It can be explicitely set/overrided with
>   * the KCONFIG_PATH environment variable as well.
>   *
> - * The kcofings array is expected to contain strings in a format "CONFIG_FOO"
> - * or "CONFIG_FOO=bar". The result array has to be suitably sized to fit the
> - * results.
> - *
> - * @param kconfigs array of config strings to look for
> - * @param results array to store results to
> - * @param cnt size of the arrays
> + * The caller has to initialize the tst_kconfig_var structure. The id has to be
> + * filled with config variable name such as 'CONFIG_FOO', the id_len should
> + * hold the id string length and the choice and val has to be zeroed.
>   *
> - * The match in the tst_kconfig_res structure is set as follows:
> + * After a call to this function each choice be set as follows:
>   *
>   *  'm' - config option set to m
>   *  'y' - config option set to y
> @@ -34,11 +34,13 @@ struct tst_kconfig_res {
>   *  'n' - config option is not set
>   *   0  - config option not found
>   *
> - * In the case that match is set to 'v' the value points to a newly allocated
> - * string that holds the value.
> + * In the case that match is set to 'v' the val pointer points to a newly
> + * allocated string that holds the value.
> + *
> + * @param vars An array of caller initalized tst_kconfig_var structures.
> + * @param vars_len Length of the vars array.
>   */
> -void tst_kconfig_read(const char *const kconfigs[],
> -		      struct tst_kconfig_res results[], size_t cnt);
> +void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len);
>  
>  /**
>   * Checks if required kernel configuration options are set in the kernel
> diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
> index d49187b6f..f80925cc9 100644
> --- a/lib/tst_kconfig.c
> +++ b/lib/tst_kconfig.c
> @@ -84,15 +84,6 @@ static void close_kconfig(FILE *fp)
>  		fclose(fp);
>  }
>  
> -struct match {
> -	/* match len, string length up to \0 or = */
> -	size_t len;
> -	/* if set part of conf string after = */
> -	const char *val;
> -	/* if set the config option was matched already */
> -	int match;
> -};
> -
>  static int is_set(const char *str, const char *val)
>  {
>  	size_t vlen = strlen(val);
> @@ -114,96 +105,70 @@ static int is_set(const char *str, const char *val)
>  	}
>  }
>  
> -static inline int match(struct match *match, const char *conf,
> -                        struct tst_kconfig_res *result, const char *line)
> +static inline int kconfig_parse_line(const char *line,
> +                                     struct tst_kconfig_var *vars,
> +                                     unsigned int vars_len)
>  {
> -	if (match->match)
> -		return 0;
> +	unsigned int i;
>  
> -	const char *cfg = strstr(line, "CONFIG_");
> +	for (i = 0; i < vars_len; i++) {
> +		if (!strncmp(vars[i].id, line, vars[i].id_len)) {
> +			const char *val = &line[vars[i].id_len];
> +

It is valid to have 'CONFIG_VAR = y'. We should probably tokenize the
lines first to remove whitespace issues and expose the parser to all
possible variable name symbols and values instead of just the ones which
appear in our current tests.

> +			switch (val[0]) {
> +			case '=':
> +				break;
> +			case ' ':
> +				if (is_set(val, "is not set")) {
> +					vars[i].choice = 'n';
> +					return 1;
> +				}

Typically such lines begin with a comment '#' and I don't see where that
is handled. Possibly this will only match non standard configs?

> +				return 1;
> +			/* vars[i].id may be prefix to longer config var */
> +			default:
> +				return 0;
> +			}
>  
> -	if (!cfg)
> -		return 0;
> +			if (is_set(val, "=y")) {
> +				vars[i].choice = 'y';
> +				return 1;
> +			}
>  
> -	if (strncmp(cfg, conf, match->len))
> -		return 0;
> +			if (is_set(val, "=m")) {
> +				vars[i].choice = 'm';
> +				return 1;
> +			}
>  
> -	const char *val = &cfg[match->len];
> +			vars[i].choice = 'v';
> +			vars[i].val = strndup(val+1, strlen(val)-2);
>  
> -	switch (cfg[match->len]) {
> -	case '=':
> -		break;
> -	case ' ':
> -		if (is_set(val, "is not set")) {
> -			result->match = 'n';
> -			goto match;
> +			return 1;
>  		}
> -	/* fall through */
> -	default:
> -		return 0;
> -	}
> -
> -	if (is_set(val, "=y")) {
> -		result->match = 'y';
> -		goto match;
>  	}
>  
> -	if (is_set(val, "=m")) {
> -		result->match = 'm';
> -		goto match;
> -	}
> -
> -	result->match = 'v';
> -	result->value = strndup(val+1, strlen(val)-2);
> -
> -match:
> -	match->match = 1;
> -	return 1;
> +	return 0;
>  }
>  
> -void tst_kconfig_read(const char *const *kconfigs,
> -                      struct tst_kconfig_res results[], size_t cnt)
> +void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len)
>  {
> -	struct match matches[cnt];
> -	FILE *fp;
> -	unsigned int i, j;
> -	char buf[1024];
> -
> -	for (i = 0; i < cnt; i++) {
> -		const char *val = strchr(kconfigs[i], '=');
> -
> -		if (strncmp("CONFIG_", kconfigs[i], 7))
> -			tst_brk(TBROK, "Invalid config string '%s'", kconfigs[i]);
> +	char line[128];
> +	unsigned int vars_found = 0;
>  
> -		matches[i].match = 0;
> -		matches[i].len = strlen(kconfigs[i]);
> -
> -		if (val) {
> -			matches[i].val = val + 1;
> -			matches[i].len -= strlen(val);
> -		}
> -
> -		results[i].match = 0;
> -		results[i].value = NULL;
> -	}
> -
> -	fp = open_kconfig();
> +	FILE *fp = open_kconfig();
>  	if (!fp)
>  		tst_brk(TBROK, "Cannot parse kernel .config");
>  
> -	while (fgets(buf, sizeof(buf), fp)) {
> -		for (i = 0; i < cnt; i++) {
> -			if (match(&matches[i], kconfigs[i], &results[i], buf)) {
> -				for (j = 0; j < cnt; j++) {
> -					if (matches[j].match)
> -						break;
> -				}
> +	while (fgets(line, sizeof(line), fp)) {
> +		char *cfg = strstr(line, "CONFIG_");
>  
> -				if (j == cnt)
> -					goto exit;
> -			}
> -		}
> +		if (!cfg)
> +			continue;

This filtering seems unecessary and maybe will hide some corner cases
because it reduces kconfig_parses_line's exposure. Also practically
every line has 'CONFIG_' in it.

> +
> +		if (kconfig_parse_line(line, vars, vars_len))
> +			vars_found++;
>  
> +		if (vars_found == vars_len)
> +			goto exit;
>  	}

Generally, this approach seems like to result in spurious TCONFs. We
need to properly parse the file and fail if some line can't be
interpreted.

>  
>  exit:
> @@ -219,42 +184,63 @@ static size_t array_len(const char *const kconfigs[])
>  	return i;
>  }
>  
> -static int compare_res(struct tst_kconfig_res *res, const char *kconfig,
> -                       char match, const char *val)
> +static int compare_res(struct tst_kconfig_var *var, const char *kconfig,
> +                       char choice, const char *val)
>  {
> -	if (res->match != match) {
> -		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, res->match);
> +	if (var->choice != choice) {
> +		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, var->choice);
>  		return 1;
>  	}
>  
> -	if (match != 'v')
> +	if (choice != 'v')
>  		return 0;
>  
> -	if (strcmp(res->value, val)) {
> -		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, res->value);
> +	if (strcmp(var->val, val)) {
> +		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, var->val);
>  		return 1;
>  	}
>  
>  	return 0;
>  }
>  
> +static inline unsigned int get_len(const char* kconfig)
> +{
> +	char *sep = index(kconfig, '=');
> +
> +	if (!sep)
> +		return strlen(kconfig);
> +
> +	return sep - kconfig;
> +}
> +
>  void tst_kconfig_check(const char *const kconfigs[])
>  {
> -	size_t cnt = array_len(kconfigs);
> -	struct tst_kconfig_res results[cnt];
> +	size_t vars_cnt = array_len(kconfigs);
> +	struct tst_kconfig_var vars[vars_cnt];
>  	unsigned int i;
>  	int abort_test = 0;
>  
> -	tst_kconfig_read(kconfigs, results, cnt);
> +	memset(vars, 0, sizeof(*vars) * vars_cnt);
> +
> +	for (i = 0; i < vars_cnt; i++) {
> +		vars[i].id_len = get_len(kconfigs[i]);
> +
> +		if (vars[i].id_len >= sizeof(vars[i].id))
> +			tst_brk(TBROK, "kconfig var id too long!");
> +
> +		strncpy(vars[i].id, kconfigs[i], vars[i].id_len);
> +	}
> +
> +	tst_kconfig_read(vars, vars_cnt);
>  
> -	for (i = 0; i < cnt; i++) {
> -		if (results[i].match == 0) {
> +	for (i = 0; i < vars_cnt; i++) {
> +		if (vars[i].choice == 0) {
>  			tst_res(TINFO, "Missing kernel %s", kconfigs[i]);
>  			abort_test = 1;
>  			continue;
>  		}
>  
> -		if (results[i].match == 'n') {
> +		if (vars[i].choice == 'n') {
>  			tst_res(TINFO, "Kernel %s is not set", kconfigs[i]);
>  			abort_test = 1;
>  			continue;
> @@ -263,21 +249,21 @@ void tst_kconfig_check(const char *const kconfigs[])
>  		const char *val = strchr(kconfigs[i], '=');
>  
>  		if (val) {
> -			char match = 'v';
> +			char choice = 'v';
>  			val++;
>  
>  			if (!strcmp(val, "y"))
> -				match = 'y';
> +				choice = 'y';
>  
>  			if (!strcmp(val, "m"))
> -				match = 'm';
> +				choice = 'm';
>  
> -			if (compare_res(&results[i], kconfigs[i], match, val))
> +			if (compare_res(&vars[i], kconfigs[i], choice, val))
>  				abort_test = 1;
>  
>  		}
>  
> -		free(results[i].value);
> +		free(vars[i].val);
>  	}
>  
>  	if (abort_test)
> -- 
> 2.26.2

I suppose most of the problems here stem from the original code, but
your patch may as well clear it up :-)

-- 
Thank you,
Richard.

[LTP] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Cyril Hrubis]

Hi!
> > diff --git a/include/tst_kconfig.h b/include/tst_kconfig.h
> > index 2d2cfd782..1bb21fea8 100644
> > --- a/include/tst_kconfig.h
> > +++ b/include/tst_kconfig.h
> > @@ -6,27 +6,27 @@
> >  #ifndef TST_KCONFIG_H__
> >  #define TST_KCONFIG_H__
> >  
> > -struct tst_kconfig_res {
> > -	char match;
> > -	char *value;
> > +struct tst_kconfig_var {
> > +	char id[64];
> > +	unsigned int id_len;
> > +	char choice;
> 
> This should probably be an enum to give the compiler more info. Even if
> we use the current char values as the enum entries.

Actually I was thinking of getting rid of this entirely in a follow up
patch and just keep the val, because after the last patch these values
are not special anymore.

> > +	char *val;
> >  };
> >  
> >  /**
> > - * Reads a kernel config and parses it for values defined in kconfigs array.
> > + *
> > + * Reads a kernel config, parses it and writes results into an array of
> > + * tst_kconfig_var structures.
> >   *
> >   * The path to the kernel config should be autodetected in most of the cases as
> >   * the code looks for know locations. It can be explicitely set/overrided with
> >   * the KCONFIG_PATH environment variable as well.
> >   *
> > - * The kcofings array is expected to contain strings in a format "CONFIG_FOO"
> > - * or "CONFIG_FOO=bar". The result array has to be suitably sized to fit the
> > - * results.
> > - *
> > - * @param kconfigs array of config strings to look for
> > - * @param results array to store results to
> > - * @param cnt size of the arrays
> > + * The caller has to initialize the tst_kconfig_var structure. The id has to be
> > + * filled with config variable name such as 'CONFIG_FOO', the id_len should
> > + * hold the id string length and the choice and val has to be zeroed.
> >   *
> > - * The match in the tst_kconfig_res structure is set as follows:
> > + * After a call to this function each choice be set as follows:
> >   *
> >   *  'm' - config option set to m
> >   *  'y' - config option set to y
> > @@ -34,11 +34,13 @@ struct tst_kconfig_res {
> >   *  'n' - config option is not set
> >   *   0  - config option not found
> >   *
> > - * In the case that match is set to 'v' the value points to a newly allocated
> > - * string that holds the value.
> > + * In the case that match is set to 'v' the val pointer points to a newly
> > + * allocated string that holds the value.
> > + *
> > + * @param vars An array of caller initalized tst_kconfig_var structures.
> > + * @param vars_len Length of the vars array.
> >   */
> > -void tst_kconfig_read(const char *const kconfigs[],
> > -		      struct tst_kconfig_res results[], size_t cnt);
> > +void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len);
> >  
> >  /**
> >   * Checks if required kernel configuration options are set in the kernel
> > diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
> > index d49187b6f..f80925cc9 100644
> > --- a/lib/tst_kconfig.c
> > +++ b/lib/tst_kconfig.c
> > @@ -84,15 +84,6 @@ static void close_kconfig(FILE *fp)
> >  		fclose(fp);
> >  }
> >  
> > -struct match {
> > -	/* match len, string length up to \0 or = */
> > -	size_t len;
> > -	/* if set part of conf string after = */
> > -	const char *val;
> > -	/* if set the config option was matched already */
> > -	int match;
> > -};
> > -
> >  static int is_set(const char *str, const char *val)
> >  {
> >  	size_t vlen = strlen(val);
> > @@ -114,96 +105,70 @@ static int is_set(const char *str, const char *val)
> >  	}
> >  }
> >  
> > -static inline int match(struct match *match, const char *conf,
> > -                        struct tst_kconfig_res *result, const char *line)
> > +static inline int kconfig_parse_line(const char *line,
> > +                                     struct tst_kconfig_var *vars,
> > +                                     unsigned int vars_len)
> >  {
> > -	if (match->match)
> > -		return 0;
> > +	unsigned int i;
> >  
> > -	const char *cfg = strstr(line, "CONFIG_");
> > +	for (i = 0; i < vars_len; i++) {
> > +		if (!strncmp(vars[i].id, line, vars[i].id_len)) {
> > +			const char *val = &line[vars[i].id_len];
> > +
> 
> It is valid to have 'CONFIG_VAR = y'. We should probably tokenize the
> lines first to remove whitespace issues and expose the parser to all
> possible variable name symbols and values instead of just the ones which
> appear in our current tests.

I guess that it's techincally possible to have a whitespaces there, but
will not happen unless you hand-edit the config file before compilation,
which I doubt will ever happen.

> > +			switch (val[0]) {
> > +			case '=':
> > +				break;
> > +			case ' ':
> > +				if (is_set(val, "is not set")) {
> > +					vars[i].choice = 'n';
> > +					return 1;
> > +				}
> 
> Typically such lines begin with a comment '#' and I don't see where that
> is handled. Possibly this will only match non standard configs?

It does work actually, since we use strstr() to get the "CONFIG_" prefix
from each line of the configuration, but I guess this needs to be fixed
anyways since we would detect "# CONFIG_FOO=y" as enabled config feature
even if it's commented. Again this will not happen unless you hand-edit
the file, but it's probably worth fixing in a follow up patch.

> > +				return 1;
> > +			/* vars[i].id may be prefix to longer config var */
> > +			default:
> > +				return 0;
> > +			}
> >  
> > -	if (!cfg)
> > -		return 0;
> > +			if (is_set(val, "=y")) {
> > +				vars[i].choice = 'y';
> > +				return 1;
> > +			}
> >  
> > -	if (strncmp(cfg, conf, match->len))
> > -		return 0;
> > +			if (is_set(val, "=m")) {
> > +				vars[i].choice = 'm';
> > +				return 1;
> > +			}
> >  
> > -	const char *val = &cfg[match->len];
> > +			vars[i].choice = 'v';
> > +			vars[i].val = strndup(val+1, strlen(val)-2);
> >  
> > -	switch (cfg[match->len]) {
> > -	case '=':
> > -		break;
> > -	case ' ':
> > -		if (is_set(val, "is not set")) {
> > -			result->match = 'n';
> > -			goto match;
> > +			return 1;
> >  		}
> > -	/* fall through */
> > -	default:
> > -		return 0;
> > -	}
> > -
> > -	if (is_set(val, "=y")) {
> > -		result->match = 'y';
> > -		goto match;
> >  	}
> >  
> > -	if (is_set(val, "=m")) {
> > -		result->match = 'm';
> > -		goto match;
> > -	}
> > -
> > -	result->match = 'v';
> > -	result->value = strndup(val+1, strlen(val)-2);
> > -
> > -match:
> > -	match->match = 1;
> > -	return 1;
> > +	return 0;
> >  }
> >  
> > -void tst_kconfig_read(const char *const *kconfigs,
> > -                      struct tst_kconfig_res results[], size_t cnt)
> > +void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len)
> >  {
> > -	struct match matches[cnt];
> > -	FILE *fp;
> > -	unsigned int i, j;
> > -	char buf[1024];
> > -
> > -	for (i = 0; i < cnt; i++) {
> > -		const char *val = strchr(kconfigs[i], '=');
> > -
> > -		if (strncmp("CONFIG_", kconfigs[i], 7))
> > -			tst_brk(TBROK, "Invalid config string '%s'", kconfigs[i]);
> > +	char line[128];
> > +	unsigned int vars_found = 0;
> >  
> > -		matches[i].match = 0;
> > -		matches[i].len = strlen(kconfigs[i]);
> > -
> > -		if (val) {
> > -			matches[i].val = val + 1;
> > -			matches[i].len -= strlen(val);
> > -		}
> > -
> > -		results[i].match = 0;
> > -		results[i].value = NULL;
> > -	}
> > -
> > -	fp = open_kconfig();
> > +	FILE *fp = open_kconfig();
> >  	if (!fp)
> >  		tst_brk(TBROK, "Cannot parse kernel .config");
> >  
> > -	while (fgets(buf, sizeof(buf), fp)) {
> > -		for (i = 0; i < cnt; i++) {
> > -			if (match(&matches[i], kconfigs[i], &results[i], buf)) {
> > -				for (j = 0; j < cnt; j++) {
> > -					if (matches[j].match)
> > -						break;
> > -				}
> > +	while (fgets(line, sizeof(line), fp)) {
> > +		char *cfg = strstr(line, "CONFIG_");
> >  
> > -				if (j == cnt)
> > -					goto exit;
> > -			}
> > -		}
> > +		if (!cfg)
> > +			continue;
> 
> This filtering seems unecessary and maybe will hide some corner cases
> because it reduces kconfig_parses_line's exposure. Also practically
> every line has 'CONFIG_' in it.

Not really, there are empty lines and plenty of comments in the file
generated by kernel infrastructure.

> > +
> > +		if (kconfig_parse_line(line, vars, vars_len))
> > +			vars_found++;
> >  
> > +		if (vars_found == vars_len)
> > +			goto exit;
> >  	}
> 
> Generally, this approach seems like to result in spurious TCONFs. We
> need to properly parse the file and fail if some line can't be
> interpreted.

Well we do expect well formatted .config file from a start, if you hand
edit it and put whitespaces into unexpected places more things may
fail.

> >  exit:
> > @@ -219,42 +184,63 @@ static size_t array_len(const char *const kconfigs[])
> >  	return i;
> >  }
> >  
> > -static int compare_res(struct tst_kconfig_res *res, const char *kconfig,
> > -                       char match, const char *val)
> > +static int compare_res(struct tst_kconfig_var *var, const char *kconfig,
> > +                       char choice, const char *val)
> >  {
> > -	if (res->match != match) {
> > -		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, res->match);
> > +	if (var->choice != choice) {
> > +		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, var->choice);
> >  		return 1;
> >  	}
> >  
> > -	if (match != 'v')
> > +	if (choice != 'v')
> >  		return 0;
> >  
> > -	if (strcmp(res->value, val)) {
> > -		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, res->value);
> > +	if (strcmp(var->val, val)) {
> > +		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, var->val);
> >  		return 1;
> >  	}
> >  
> >  	return 0;
> >  }
> >  
> > +static inline unsigned int get_len(const char* kconfig)
> > +{
> > +	char *sep = index(kconfig, '=');
> > +
> > +	if (!sep)
> > +		return strlen(kconfig);
> > +
> > +	return sep - kconfig;
> > +}
> > +
> >  void tst_kconfig_check(const char *const kconfigs[])
> >  {
> > -	size_t cnt = array_len(kconfigs);
> > -	struct tst_kconfig_res results[cnt];
> > +	size_t vars_cnt = array_len(kconfigs);
> > +	struct tst_kconfig_var vars[vars_cnt];
> >  	unsigned int i;
> >  	int abort_test = 0;
> >  
> > -	tst_kconfig_read(kconfigs, results, cnt);
> > +	memset(vars, 0, sizeof(*vars) * vars_cnt);
> > +
> > +	for (i = 0; i < vars_cnt; i++) {
> > +		vars[i].id_len = get_len(kconfigs[i]);
> > +
> > +		if (vars[i].id_len >= sizeof(vars[i].id))
> > +			tst_brk(TBROK, "kconfig var id too long!");
> > +
> > +		strncpy(vars[i].id, kconfigs[i], vars[i].id_len);
> > +	}
> > +
> > +	tst_kconfig_read(vars, vars_cnt);
> >  
> > -	for (i = 0; i < cnt; i++) {
> > -		if (results[i].match == 0) {
> > +	for (i = 0; i < vars_cnt; i++) {
> > +		if (vars[i].choice == 0) {
> >  			tst_res(TINFO, "Missing kernel %s", kconfigs[i]);
> >  			abort_test = 1;
> >  			continue;
> >  		}
> >  
> > -		if (results[i].match == 'n') {
> > +		if (vars[i].choice == 'n') {
> >  			tst_res(TINFO, "Kernel %s is not set", kconfigs[i]);
> >  			abort_test = 1;
> >  			continue;
> > @@ -263,21 +249,21 @@ void tst_kconfig_check(const char *const kconfigs[])
> >  		const char *val = strchr(kconfigs[i], '=');
> >  
> >  		if (val) {
> > -			char match = 'v';
> > +			char choice = 'v';
> >  			val++;
> >  
> >  			if (!strcmp(val, "y"))
> > -				match = 'y';
> > +				choice = 'y';
> >  
> >  			if (!strcmp(val, "m"))
> > -				match = 'm';
> > +				choice = 'm';
> >  
> > -			if (compare_res(&results[i], kconfigs[i], match, val))
> > +			if (compare_res(&vars[i], kconfigs[i], choice, val))
> >  				abort_test = 1;
> >  
> >  		}
> >  
> > -		free(results[i].value);
> > +		free(vars[i].val);
> >  	}
> >  
> >  	if (abort_test)
> > -- 
> > 2.26.2
> 
> I suppose most of the problems here stem from the original code, but
> your patch may as well clear it up :-)

Actually the clear way how to fix this is in a separate patch so that
logical changes are split into different patches.

-- 
Cyril Hrubis
chrubis@suse.cz

[LTP] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Richard Palethorpe]

Hello,

Cyril Hrubis <chrubis@suse.cz> writes:

>> >  
>> > -static inline int match(struct match *match, const char *conf,
>> > -                        struct tst_kconfig_res *result, const char *line)
>> > +static inline int kconfig_parse_line(const char *line,
>> > +                                     struct tst_kconfig_var *vars,
>> > +                                     unsigned int vars_len)
>> >  {
>> > -	if (match->match)
>> > -		return 0;
>> > +	unsigned int i;
>> >  
>> > -	const char *cfg = strstr(line, "CONFIG_");
>> > +	for (i = 0; i < vars_len; i++) {
>> > +		if (!strncmp(vars[i].id, line, vars[i].id_len)) {
>> > +			const char *val = &line[vars[i].id_len];
>> > +
>> 
>> It is valid to have 'CONFIG_VAR = y'. We should probably tokenize the
>> lines first to remove whitespace issues and expose the parser to all
>> possible variable name symbols and values instead of just the ones which
>> appear in our current tests.
>
> I guess that it's techincally possible to have a whitespaces there, but
> will not happen unless you hand-edit the config file before compilation,
> which I doubt will ever happen.
>

It can also happen if someone has their own script to modify the
config. At any rate, if you are confident that it will never happen then
there should be no problem failing hard if it does.

>> > +			switch (val[0]) {
>> > +			case '=':
>> > +				break;
>> > +			case ' ':
>> > +				if (is_set(val, "is not set")) {
>> > +					vars[i].choice = 'n';
>> > +					return 1;
>> > +				}
>> 
>> Typically such lines begin with a comment '#' and I don't see where that
>> is handled. Possibly this will only match non standard configs?
>
> It does work actually, since we use strstr() to get the "CONFIG_" prefix
> from each line of the configuration, but I guess this needs to be fixed
> anyways since we would detect "# CONFIG_FOO=y" as enabled config feature
> even if it's commented. Again this will not happen unless you hand-edit
> the file, but it's probably worth fixing in a follow up patch.

We don't actually use the result of strstr anymore?

>
>> > +				return 1;
>> > +			/* vars[i].id may be prefix to longer config var */
>> > +			default:
>> > +				return 0;
>> > +			}
>> >  
>> > -	if (!cfg)
>> > -		return 0;
>> > +			if (is_set(val, "=y")) {
>> > +				vars[i].choice = 'y';
>> > +				return 1;
>> > +			}
>> >  
>> > -	if (strncmp(cfg, conf, match->len))
>> > -		return 0;
>> > +			if (is_set(val, "=m")) {
>> > +				vars[i].choice = 'm';
>> > +				return 1;
>> > +			}
>> >  
>> > -	const char *val = &cfg[match->len];
>> > +			vars[i].choice = 'v';
>> > +			vars[i].val = strndup(val+1, strlen(val)-2);
>> >  
>> > -	switch (cfg[match->len]) {
>> > -	case '=':
>> > -		break;
>> > -	case ' ':
>> > -		if (is_set(val, "is not set")) {
>> > -			result->match = 'n';
>> > -			goto match;
>> > +			return 1;
>> >  		}
>> > -	/* fall through */
>> > -	default:
>> > -		return 0;
>> > -	}
>> > -
>> > -	if (is_set(val, "=y")) {
>> > -		result->match = 'y';
>> > -		goto match;
>> >  	}
>> >  
>> > -	if (is_set(val, "=m")) {
>> > -		result->match = 'm';
>> > -		goto match;
>> > -	}
>> > -
>> > -	result->match = 'v';
>> > -	result->value = strndup(val+1, strlen(val)-2);
>> > -
>> > -match:
>> > -	match->match = 1;
>> > -	return 1;
>> > +	return 0;
>> >  }
>> >  
>> > -void tst_kconfig_read(const char *const *kconfigs,
>> > -                      struct tst_kconfig_res results[], size_t cnt)
>> > +void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len)
>> >  {
>> > -	struct match matches[cnt];
>> > -	FILE *fp;
>> > -	unsigned int i, j;
>> > -	char buf[1024];
>> > -
>> > -	for (i = 0; i < cnt; i++) {
>> > -		const char *val = strchr(kconfigs[i], '=');
>> > -
>> > -		if (strncmp("CONFIG_", kconfigs[i], 7))
>> > -			tst_brk(TBROK, "Invalid config string '%s'", kconfigs[i]);
>> > +	char line[128];
>> > +	unsigned int vars_found = 0;
>> >  
>> > -		matches[i].match = 0;
>> > -		matches[i].len = strlen(kconfigs[i]);
>> > -
>> > -		if (val) {
>> > -			matches[i].val = val + 1;
>> > -			matches[i].len -= strlen(val);
>> > -		}
>> > -
>> > -		results[i].match = 0;
>> > -		results[i].value = NULL;
>> > -	}
>> > -
>> > -	fp = open_kconfig();
>> > +	FILE *fp = open_kconfig();
>> >  	if (!fp)
>> >  		tst_brk(TBROK, "Cannot parse kernel .config");
>> >  
>> > -	while (fgets(buf, sizeof(buf), fp)) {
>> > -		for (i = 0; i < cnt; i++) {
>> > -			if (match(&matches[i], kconfigs[i], &results[i], buf)) {
>> > -				for (j = 0; j < cnt; j++) {
>> > -					if (matches[j].match)
>> > -						break;
>> > -				}
>> > +	while (fgets(line, sizeof(line), fp)) {
>> > +		char *cfg = strstr(line, "CONFIG_");
>> >  
>> > -				if (j == cnt)
>> > -					goto exit;
>> > -			}
>> > -		}
>> > +		if (!cfg)
>> > +			continue;
>> 
>> This filtering seems unecessary and maybe will hide some corner cases
>> because it reduces kconfig_parses_line's exposure. Also practically
>> every line has 'CONFIG_' in it.
>
> Not really, there are empty lines and plenty of comments in the file
> generated by kernel infrastructure.

It seems about 80-90% of lines contain CONFIG_, however if you pass it
to kconfig_parse_line then this makes more sense. Still I think with
proper parsing this shouldn't be there.

>
>> > +
>> > +		if (kconfig_parse_line(line, vars, vars_len))
>> > +			vars_found++;
>> >  
>> > +		if (vars_found == vars_len)
>> > +			goto exit;
>> >  	}
>> 
>> Generally, this approach seems like to result in spurious TCONFs. We
>> need to properly parse the file and fail if some line can't be
>> interpreted.
>
> Well we do expect well formatted .config file from a start, if you hand
> edit it and put whitespaces into unexpected places more things may
> fail.

Kernel build system seems to have no problem with it. More generally
though we should fail hard if there is something unexpected, not produce
TCONF which people don't check.

>
>> >  exit:
>> > @@ -219,42 +184,63 @@ static size_t array_len(const char *const kconfigs[])
>> >  	return i;
>> >  }
>> >  
>> > -static int compare_res(struct tst_kconfig_res *res, const char *kconfig,
>> > -                       char match, const char *val)
>> > +static int compare_res(struct tst_kconfig_var *var, const char *kconfig,
>> > +                       char choice, const char *val)
>> >  {
>> > -	if (res->match != match) {
>> > -		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, res->match);
>> > +	if (var->choice != choice) {
>> > +		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, var->choice);
>> >  		return 1;
>> >  	}
>> >  
>> > -	if (match != 'v')
>> > +	if (choice != 'v')
>> >  		return 0;
>> >  
>> > -	if (strcmp(res->value, val)) {
>> > -		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, res->value);
>> > +	if (strcmp(var->val, val)) {
>> > +		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, var->val);
>> >  		return 1;
>> >  	}
>> >  
>> >  	return 0;
>> >  }
>> >  
>> > +static inline unsigned int get_len(const char* kconfig)
>> > +{
>> > +	char *sep = index(kconfig, '=');
>> > +
>> > +	if (!sep)
>> > +		return strlen(kconfig);
>> > +
>> > +	return sep - kconfig;
>> > +}
>> > +
>> >  void tst_kconfig_check(const char *const kconfigs[])
>> >  {
>> > -	size_t cnt = array_len(kconfigs);
>> > -	struct tst_kconfig_res results[cnt];
>> > +	size_t vars_cnt = array_len(kconfigs);
>> > +	struct tst_kconfig_var vars[vars_cnt];
>> >  	unsigned int i;
>> >  	int abort_test = 0;
>> >  
>> > -	tst_kconfig_read(kconfigs, results, cnt);
>> > +	memset(vars, 0, sizeof(*vars) * vars_cnt);
>> > +
>> > +	for (i = 0; i < vars_cnt; i++) {
>> > +		vars[i].id_len = get_len(kconfigs[i]);
>> > +
>> > +		if (vars[i].id_len >= sizeof(vars[i].id))
>> > +			tst_brk(TBROK, "kconfig var id too long!");
>> > +
>> > +		strncpy(vars[i].id, kconfigs[i], vars[i].id_len);
>> > +	}
>> > +
>> > +	tst_kconfig_read(vars, vars_cnt);
>> >  
>> > -	for (i = 0; i < cnt; i++) {
>> > -		if (results[i].match == 0) {
>> > +	for (i = 0; i < vars_cnt; i++) {
>> > +		if (vars[i].choice == 0) {
>> >  			tst_res(TINFO, "Missing kernel %s", kconfigs[i]);
>> >  			abort_test = 1;
>> >  			continue;
>> >  		}
>> >  
>> > -		if (results[i].match == 'n') {
>> > +		if (vars[i].choice == 'n') {
>> >  			tst_res(TINFO, "Kernel %s is not set", kconfigs[i]);
>> >  			abort_test = 1;
>> >  			continue;
>> > @@ -263,21 +249,21 @@ void tst_kconfig_check(const char *const kconfigs[])
>> >  		const char *val = strchr(kconfigs[i], '=');
>> >  
>> >  		if (val) {
>> > -			char match = 'v';
>> > +			char choice = 'v';
>> >  			val++;
>> >  
>> >  			if (!strcmp(val, "y"))
>> > -				match = 'y';
>> > +				choice = 'y';
>> >  
>> >  			if (!strcmp(val, "m"))
>> > -				match = 'm';
>> > +				choice = 'm';
>> >  
>> > -			if (compare_res(&results[i], kconfigs[i], match, val))
>> > +			if (compare_res(&vars[i], kconfigs[i], choice, val))
>> >  				abort_test = 1;
>> >  
>> >  		}
>> >  
>> > -		free(results[i].value);
>> > +		free(vars[i].val);
>> >  	}
>> >  
>> >  	if (abort_test)
>> > -- 
>> > 2.26.2
>> 
>> I suppose most of the problems here stem from the original code, but
>> your patch may as well clear it up :-)
>
> Actually the clear way how to fix this is in a separate patch so that
> logical changes are split into different patches.

I suppose that elements of the boolean parser can be used to parse the
kconfig and it can be combined (in a later patch). It's kind of
unecessary to parse a config file into RPN, but will work perfectly well
so we can share some code here.

-- 
Thank you,
Richard.

[LTP] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Cyril Hrubis]

Hi!
> >> lines first to remove whitespace issues and expose the parser to all
> >> possible variable name symbols and values instead of just the ones which
> >> appear in our current tests.
> >
> > I guess that it's techincally possible to have a whitespaces there, but
> > will not happen unless you hand-edit the config file before compilation,
> > which I doubt will ever happen.
> >
> 
> It can also happen if someone has their own script to modify the
> config. At any rate, if you are confident that it will never happen then
> there should be no problem failing hard if it does.

It would be probably easier to eat the whitespace around the = if
present. But still I would ignore anything that isn't correct variable
assignment, since such config would fail kernel compilation anyways.

> >> > +			switch (val[0]) {
> >> > +			case '=':
> >> > +				break;
> >> > +			case ' ':
> >> > +				if (is_set(val, "is not set")) {
> >> > +					vars[i].choice = 'n';
> >> > +					return 1;
> >> > +				}
> >> 
> >> Typically such lines begin with a comment '#' and I don't see where that
> >> is handled. Possibly this will only match non standard configs?
> >
> > It does work actually, since we use strstr() to get the "CONFIG_" prefix
> > from each line of the configuration, but I guess this needs to be fixed
> > anyways since we would detect "# CONFIG_FOO=y" as enabled config feature
> > even if it's commented. Again this will not happen unless you hand-edit
> > the file, but it's probably worth fixing in a follow up patch.
> 
> We don't actually use the result of strstr anymore?

Ah right, that's a bug, the cfg should be passed to the
kconfig_parse_line() instead, at least that's how the previous version
worked in order to differentiate between unset and unknown variables.

> >> > +				return 1;
> >> > +			/* vars[i].id may be prefix to longer config var */
> >> > +			default:
> >> > +				return 0;
> >> > +			}
> >> >  
> >> > -	if (!cfg)
> >> > -		return 0;
> >> > +			if (is_set(val, "=y")) {
> >> > +				vars[i].choice = 'y';
> >> > +				return 1;
> >> > +			}
> >> >  
> >> > -	if (strncmp(cfg, conf, match->len))
> >> > -		return 0;
> >> > +			if (is_set(val, "=m")) {
> >> > +				vars[i].choice = 'm';
> >> > +				return 1;
> >> > +			}
> >> >  
> >> > -	const char *val = &cfg[match->len];
> >> > +			vars[i].choice = 'v';
> >> > +			vars[i].val = strndup(val+1, strlen(val)-2);
> >> >  
> >> > -	switch (cfg[match->len]) {
> >> > -	case '=':
> >> > -		break;
> >> > -	case ' ':
> >> > -		if (is_set(val, "is not set")) {
> >> > -			result->match = 'n';
> >> > -			goto match;
> >> > +			return 1;
> >> >  		}
> >> > -	/* fall through */
> >> > -	default:
> >> > -		return 0;
> >> > -	}
> >> > -
> >> > -	if (is_set(val, "=y")) {
> >> > -		result->match = 'y';
> >> > -		goto match;
> >> >  	}
> >> >  
> >> > -	if (is_set(val, "=m")) {
> >> > -		result->match = 'm';
> >> > -		goto match;
> >> > -	}
> >> > -
> >> > -	result->match = 'v';
> >> > -	result->value = strndup(val+1, strlen(val)-2);
> >> > -
> >> > -match:
> >> > -	match->match = 1;
> >> > -	return 1;
> >> > +	return 0;
> >> >  }
> >> >  
> >> > -void tst_kconfig_read(const char *const *kconfigs,
> >> > -                      struct tst_kconfig_res results[], size_t cnt)
> >> > +void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len)
> >> >  {
> >> > -	struct match matches[cnt];
> >> > -	FILE *fp;
> >> > -	unsigned int i, j;
> >> > -	char buf[1024];
> >> > -
> >> > -	for (i = 0; i < cnt; i++) {
> >> > -		const char *val = strchr(kconfigs[i], '=');
> >> > -
> >> > -		if (strncmp("CONFIG_", kconfigs[i], 7))
> >> > -			tst_brk(TBROK, "Invalid config string '%s'", kconfigs[i]);
> >> > +	char line[128];
> >> > +	unsigned int vars_found = 0;
> >> >  
> >> > -		matches[i].match = 0;
> >> > -		matches[i].len = strlen(kconfigs[i]);
> >> > -
> >> > -		if (val) {
> >> > -			matches[i].val = val + 1;
> >> > -			matches[i].len -= strlen(val);
> >> > -		}
> >> > -
> >> > -		results[i].match = 0;
> >> > -		results[i].value = NULL;
> >> > -	}
> >> > -
> >> > -	fp = open_kconfig();
> >> > +	FILE *fp = open_kconfig();
> >> >  	if (!fp)
> >> >  		tst_brk(TBROK, "Cannot parse kernel .config");
> >> >  
> >> > -	while (fgets(buf, sizeof(buf), fp)) {
> >> > -		for (i = 0; i < cnt; i++) {
> >> > -			if (match(&matches[i], kconfigs[i], &results[i], buf)) {
> >> > -				for (j = 0; j < cnt; j++) {
> >> > -					if (matches[j].match)
> >> > -						break;
> >> > -				}
> >> > +	while (fgets(line, sizeof(line), fp)) {
> >> > +		char *cfg = strstr(line, "CONFIG_");
> >> >  
> >> > -				if (j == cnt)
> >> > -					goto exit;
> >> > -			}
> >> > -		}
> >> > +		if (!cfg)
> >> > +			continue;
> >> 
> >> This filtering seems unecessary and maybe will hide some corner cases
> >> because it reduces kconfig_parses_line's exposure. Also practically
> >> every line has 'CONFIG_' in it.
> >
> > Not really, there are empty lines and plenty of comments in the file
> > generated by kernel infrastructure.
> 
> It seems about 80-90% of lines contain CONFIG_, however if you pass it
> to kconfig_parse_line then this makes more sense. Still I think with
> proper parsing this shouldn't be there.

What exactly do you mean by a proper parsing?

The file is format is very simple each line starts either with # which
is a comment or consists of 'key=val' pair and the key is by definition
prefixed with CONFIG_.

> >> > +
> >> > +		if (kconfig_parse_line(line, vars, vars_len))
> >> > +			vars_found++;
> >> >  
> >> > +		if (vars_found == vars_len)
> >> > +			goto exit;
> >> >  	}
> >> 
> >> Generally, this approach seems like to result in spurious TCONFs. We
> >> need to properly parse the file and fail if some line can't be
> >> interpreted.
> >
> > Well we do expect well formatted .config file from a start, if you hand
> > edit it and put whitespaces into unexpected places more things may
> > fail.
> 
> Kernel build system seems to have no problem with it. More generally
> though we should fail hard if there is something unexpected, not produce
> TCONF which people don't check.

Even if we do I do not think that we should care about anything but
syntactically correct input, since if you modify the file after kernel
compilation you have lost anyways.

> >> I suppose most of the problems here stem from the original code, but
> >> your patch may as well clear it up :-)
> >
> > Actually the clear way how to fix this is in a separate patch so that
> > logical changes are split into different patches.
> 
> I suppose that elements of the boolean parser can be used to parse the
> kconfig and it can be combined (in a later patch). It's kind of
> unecessary to parse a config file into RPN, but will work perfectly well
> so we can share some code here.

I do not get what you are trying to say. Are you saying that we should
tokenize the input? I do not think that this is necessary since the file
format is pretty simple.

-- 
Cyril Hrubis
chrubis@suse.cz

[LTP] [Automated-testing] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Petr Vorel]

Hi,

> > >> lines first to remove whitespace issues and expose the parser to all
> > >> possible variable name symbols and values instead of just the ones which
> > >> appear in our current tests.

> > > I guess that it's techincally possible to have a whitespaces there, but
> > > will not happen unless you hand-edit the config file before compilation,
> > > which I doubt will ever happen.


> > It can also happen if someone has their own script to modify the
> > config. At any rate, if you are confident that it will never happen then
> > there should be no problem failing hard if it does.

> It would be probably easier to eat the whitespace around the = if
> present. But still I would ignore anything that isn't correct variable
> assignment, since such config would fail kernel compilation anyways.
+1

+ I use ./scripts/config --enable | --disable ... to avoid problems with
incorrect config.

> > >> > +
> > >> > +		if (kconfig_parse_line(line, vars, vars_len))
> > >> > +			vars_found++;

> > >> > +		if (vars_found == vars_len)
> > >> > +			goto exit;
> > >> >  	}

> > >> Generally, this approach seems like to result in spurious TCONFs. We
> > >> need to properly parse the file and fail if some line can't be
> > >> interpreted.

> > > Well we do expect well formatted .config file from a start, if you hand
> > > edit it and put whitespaces into unexpected places more things may
> > > fail.

> > Kernel build system seems to have no problem with it. More generally
> > though we should fail hard if there is something unexpected, not produce
> > TCONF which people don't check.

> Even if we do I do not think that we should care about anything but
> syntactically correct input, since if you modify the file after kernel
> compilation you have lost anyways.
+1

Kind regards,
Petr

[LTP] [PATCH 2/3] lib: Add generic boolean expression parser and eval

[Richard Palethorpe]

Hello,

Cyril Hrubis <chrubis@suse.cz> writes:

> Add a simple and generic boolean expression parser and evaluator. This
> is a second step in order to implement more complex kconfig expressions,
> but since we are likely to reuse the parser for other purposes in the
> future it's implemented as a generic boolean parser.

This looks really excellent in general!

>
> Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
> ---
>  include/tst_bool_expr.h          |  80 +++++
>  lib/newlib_tests/.gitignore      |   1 +
>  lib/newlib_tests/tst_bool_expr.c | 127 ++++++++
>  lib/tst_bool_expr.c              | 504 +++++++++++++++++++++++++++++++
>  4 files changed, 712 insertions(+)
>  create mode 100644 include/tst_bool_expr.h
>  create mode 100644 lib/newlib_tests/tst_bool_expr.c
>  create mode 100644 lib/tst_bool_expr.c
>
> diff --git a/include/tst_bool_expr.h b/include/tst_bool_expr.h
> new file mode 100644
> index 000000000..e163690ab
> --- /dev/null
> +++ b/include/tst_bool_expr.h
> @@ -0,0 +1,80 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2020 Cyril Hrubis <chrubis@suse.cz>
> + */
> +
> +#ifndef TST_BOOL_EXPR_H__
> +#define TST_BOOL_EXPR_H__
> +
> +enum tst_op {
> +	TST_OP_NOT,
> +	TST_OP_AND,
> +	TST_OP_OR,
> +	TST_OP_VAR,
> +	/* Used only internally */
> +	TST_OP_LPAR,
> +	TST_OP_RPAR,
> +};
> +
> +struct tst_expr {
> +	enum tst_op op;
> +	struct tst_expr *next;
> +	char *err;
> +	void *priv;

I'm not sure if this is used?

> +	char val[];

This could be replaced by 'struct tok', see below.

> +};
> +
> +/*
> + * Parses an boolean expression and returns a simplified RPN version.
> + *
> + * If expression is not valid the call prints error into stderr and returns
> + * NULL. On success pointer to an expression is returned which can be evaluated
> + * by the tst_bool_expr_eval() function and has to be later freed by the
> + * caller.
> + *
> + * The boolean expression can consists of:
> + *
> + * - unary negation opeartion !
> + * - two binary operations & and |
> + * - correct sequence of parentheses ()
> + * - strings that are treated as boolean variables
> + *
> + *  e.g. '(A | B) & C' or 'Variable_1 & Variable_2' are both a valid boolean
> + *  expressions.
> + *
> + *  @expr String containing a boolean expression to be parsed.
> + *  @return Pointer to an RPN expression.
> + */
> +struct tst_expr *tst_bool_expr_parse(const char *expr);
> +
> +/*
> + * Prints an string representation of the expression into a FILE.
> + *
> + * @param A FILE to print to.
> + * @expr An expression to print.
> + */
> +void tst_bool_expr_print(FILE *f, struct tst_expr *expr);
> +
> +/*
> + * Evaluates an expression given a map for variables.
> + *
> + * The call will fail if:
> + * - map function returns -1 which indicates undefined variable
> + * - the eval function runs out of stack
> + *
> + * @param expr Boolean expression in RPN.
> + * @param map Mapping function for boolean variables.
> + *
> + * @return Returns 0 or 1 if expression was evaluated correctly and -1 on error.
> + */
> +int tst_bool_expr_eval(struct tst_expr *expr,
> +                       int (*map)(struct tst_expr *var));
> +
> +/*
> + * Frees the memory allocated by the tst_bool_expr_parse().
> + *
> + * @param Boolean expression.
> + */
> +void tst_bool_expr_free(struct tst_expr *expr);
> +
> +#endif	/* TST_BOOL_EXPR_H__ */
> diff --git a/lib/newlib_tests/.gitignore b/lib/newlib_tests/.gitignore
> index 44bc6526f..1e96db1da 100644
> --- a/lib/newlib_tests/.gitignore
> +++ b/lib/newlib_tests/.gitignore
> @@ -33,3 +33,4 @@ test_exec_child
>  test_kconfig
>  variant
>  test_guarded_buf
> +tst_bool_expr
> diff --git a/lib/newlib_tests/tst_bool_expr.c b/lib/newlib_tests/tst_bool_expr.c
> new file mode 100644
> index 000000000..5f5e618dc
> --- /dev/null
> +++ b/lib/newlib_tests/tst_bool_expr.c
> @@ -0,0 +1,127 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2017 Cyril Hrubis <chrubis@suse.cz>
> + */
> +
> +/*
> + * Basic unit test for the tst_strstatus() function.
> + */
> +
> +#include <string.h>
> +#include <stdio.h>
> +#include "tst_test.h"
> +#include "tst_bool_expr.h"
> +
> +static int a, b, c;
> +
> +static int map(struct tst_expr *var)
> +{
> +	if (!strcmp(var->val, "A"))
> +		return a;
> +
> +	if (!strcmp(var->val, "B"))
> +		return b;
> +
> +	if (!strcmp(var->val, "C"))
> +		return c;
> +
> +	if (!strcmp(var->val, "True"))
> +		return 1;
> +
> +	if (!strcmp(var->val, "False"))
> +		return 0;
> +
> +	return -1;
> +}
> +
> +static void parse_fail(const char *expr)
> +{
> +	struct tst_expr *res;
> +
> +	tst_res(TINFO, "Parsing '%s'", expr);
> +
> +	res = tst_bool_expr_parse(expr);
> +
> +	if (res) {
> +		printf("In RPN: ");
> +		tst_bool_expr_print(stdout, res);
> +		printf("\n");
> +		tst_bool_expr_free(res);
> +		tst_res(TFAIL, "Expression was parsed");
> +	} else {
> +		tst_res(TPASS, "Parser returned an error");
> +	}
> +}
> +
> +static void do_eval_test(const char *expr_str, int set_a, int set_b, int set_c, int exp_res)
> +{
> +	struct tst_expr *expr;
> +	int res;
> +
> +	a = set_a;
> +	b = set_b;
> +	c = set_c;
> +
> +	tst_res(TINFO, "'%s' A=%i B=%i C=%i == %i", expr_str, a, b, c, exp_res);
> +
> +	expr = tst_bool_expr_parse(expr_str);
> +
> +	if (!expr) {
> +		tst_res(TFAIL, "Parser returned error");
> +		return;
> +	}
> +
> +	printf("In RPN: ");
> +	tst_bool_expr_print(stdout, expr);
> +	printf("\n");
> +
> +	res = tst_bool_expr_eval(expr, map);
> +
> +	if (res == exp_res)
> +		tst_res(TPASS, "Got %i", res);
> +	else
> +		tst_res(TFAIL, "Got %i", res);
> +
> +	tst_bool_expr_free(expr);
> +}
> +
> +static void do_test(void)
> +{
> +	do_eval_test("(A | B) & !!C", 0, 0, 0, 0);
> +	do_eval_test("(A | B) & !!C", 1, 0, 1, 1);
> +	do_eval_test("!A & B", 1, 0, 0, 0);
> +	do_eval_test("!A & B", 0, 1, 0, 1);
> +	do_eval_test("A & !B", 1, 0, 0, 1);
> +	do_eval_test("!!A & !!B", 0, 1, 0, 0);
> +	do_eval_test("!!A & !!B", 1, 1, 0, 1);
> +	do_eval_test("!(A & B) & C", 1, 1, 0, 0);
> +	do_eval_test("A & (B | C)", 1, 1, 0, 1);
> +	do_eval_test("((((A)))&(B))", 1, 1, 0, 1);
> +	do_eval_test("True | A", 0, 0, 0, 1);
> +	do_eval_test("False & A", 1, 0, 0, 0);
> +	do_eval_test("! Undefined", 0, 0, 0, -1);

Can we also test "A & B | C" without brackets?

> +
> +	parse_fail("A!");
> +	parse_fail("A &");
> +	parse_fail("A B");
> +	parse_fail("A ) B");
> +	parse_fail("A ( B");
> +	parse_fail("A ( B )");
> +	parse_fail("A |");
> +	parse_fail("A ! B");
> +	parse_fail("A! & B");
> +	parse_fail("A & | B");
> +	parse_fail("A & (B |)");
> +	parse_fail("A & ( | B)");
> +	parse_fail("A & B &");
> +	parse_fail("((A )");
> +	parse_fail("& A");
> +	parse_fail("! &");
> +	parse_fail(")");
> +	parse_fail("| A");
> +	parse_fail("");
> +}
> +
> +static struct tst_test test = {
> +	.test_all = do_test,
> +};
> diff --git a/lib/tst_bool_expr.c b/lib/tst_bool_expr.c
> new file mode 100644
> index 000000000..3cb395664
> --- /dev/null
> +++ b/lib/tst_bool_expr.c
> @@ -0,0 +1,504 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2020 Cyril Hrubis <chrubis@suse.cz>
> + */
> +/*
> + * Boolean expression is evaluated in three steps.
> + *
> + * First of all the string containing the expression is tokenized.
> + *
> + * Secondly the the expression is transformed to a postfix (RPN) notation by
> + * the shunting yard algorithm and the correctness of the expression is checked
> + * during the transformation as well. The fact that parenthesis are matched is
> + * asserted by the shunting yard algorithm itself while the rest is checked
> + * simply by checking if the preceding token is in a set of allowed tokens.
> + * This could be thought of as a simple open-coded state machine.
> + *
> + * An expression in the RPN form can be evaluated given a variable mapping
> + * function. The evaluation ignores most of errors because invalid expression
> + * will be rejected in the second step.
> + */
> +
> +#include <string.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include "tst_bool_expr.h"
> +
> +#define MAX_TOK 1024
> +
> +struct tok {
> +	unsigned int pos;
> +	char buf[MAX_TOK];

Instead we could save an index into the input string here and record the
length. Then there is no need to copy the string or guess a suitable
buffer length and we record the original token location for error
reporting (although it seems you reconstruct the expression so it's not
so useful).

Ofcourse that assumes the original string will remain in memory, but
usually it will be a static string in tst_test. If we use the same
parser for .config, then it still could just be mmapped in until we have
finished with it.

I guess if we used the same tokenizer for the concurrent executor then
the original string may not exist, but that can be dealt with later.

> +};
> +
> +static inline void tok_append(struct tok *tok, char c)
> +{
> +	if (tok->pos + 2 >= MAX_TOK) {
> +		tok->buf[tok->pos+1] = 0;
> +		fprintf(stderr, "Truncating token '%s'!", tok->buf);
> +	}
> +
> +	tok->buf[tok->pos++] = c;
> +}
> +
> +static inline char *tok_get(struct tok *tok)
> +{
> +	if (!tok->pos)
> +		return NULL;
> +
> +	tok->buf[tok->pos] = '\0';
> +
> +	tok->pos = 0;
> +
> +	return tok->buf;
> +}
> +
> +static struct tst_expr *new_var(const char *val)

This could be modifed to accept 'struct tok' instead of a null
terminated string. In any case it shouldn't the arg be const?

> +{
> +	struct tst_expr *ret;
> +
> +	if (!val)
> +		return NULL;
> +
> +	ret = malloc(sizeof(struct tst_expr) + strlen(val) + 1);
> +	if (!ret)
> +		return NULL;
> +
> +	ret->op = TST_OP_VAR;
> +	ret->next = NULL;
> +	ret->err = NULL;
> +	strcpy(ret->val, val);

and another string copy can be removed.

> +
> +	return ret;
> +}
> +
> +enum tst_op char_to_op(char c)
> +{
> +	switch (c) {
> +	case '(':
> +		return TST_OP_LPAR;
> +	case ')':
> +		return TST_OP_RPAR;
> +	case '&':
> +		return TST_OP_AND;
> +	case '|':
> +		return TST_OP_OR;
> +	case '!':
> +		return TST_OP_NOT;
> +	default:
> +		return -1;

This should probably be an enum value like TST_OP_INVAL (still may be
-1), otherwise it is likely to confuse static anlyses tools.

> +	}
> +}
> +
> +static struct tst_expr *new_op(char c)
> +{
> +	struct tst_expr *ret;
> +
> +	ret = malloc(sizeof(struct tst_expr));
> +	if (!ret)
> +		return NULL;
> +
> +	ret->op = char_to_op(c);
> +	ret->next = NULL;
> +	ret->err = NULL;
> +
> +	return ret;
> +}
> +
> +struct op_list {
> +	struct tst_expr *first;
> +	struct tst_expr *last;
> +	unsigned int cnt;
> +};
> +
> +static void op_list_append(struct op_list *list, struct tst_expr *val)
> +{
> +	if (!val)
> +		return;
> +
> +	if (!list->first)
> +		list->first = val;
> +
> +	if (list->last)
> +		list->last->next = val;
> +
> +	list->last = val;
> +
> +	list->cnt++;
> +}
> +
> +static void tokenize(const char *expr, struct op_list *ret)
> +{
> +	struct tok buf = {};
> +	size_t i;
> +
> +	for (i = 0; expr[i]; i++) {
> +		switch (expr[i]) {
> +		case '(':
> +		case ')':
> +		case '!':
> +		case '&':
> +		case '|':
> +			op_list_append(ret, new_var(tok_get(&buf)));
> +			op_list_append(ret, new_op(expr[i]));
> +		break;
> +		case '\t':
> +		case ' ':
> +			op_list_append(ret, new_var(tok_get(&buf)));
> +		break;
> +		default:
> +			tok_append(&buf, expr[i]);
> +		break;
> +		}
> +	}
> +
> +	op_list_append(ret, new_var(tok_get(&buf)));
> +}
> +
> +void tst_bool_expr_print(FILE *f, struct tst_expr *expr)
> +{
> +	struct tst_expr *i;
> +	int prev_op = 0;
> +
> +	for (i = expr; i; i = i->next) {
> +		if (i->op != TST_OP_VAR && prev_op)
> +			fprintf(f, " ");
> +
> +		switch (i->op) {
> +		case TST_OP_AND:
> +			fprintf(f, "&");
> +		break;
> +		case TST_OP_OR:
> +			fprintf(f, "|");
> +		break;
> +		case TST_OP_NOT:
> +			fprintf(f, "!");
> +		break;
> +		case TST_OP_LPAR:
> +			fprintf(f, "(");
> +		break;
> +		case TST_OP_RPAR:
> +			fprintf(f, ")");
> +		break;
> +		case TST_OP_VAR:
> +			fprintf(f, " %s ", i->val);
> +		break;
> +		}
> +
> +		if (i->op == TST_OP_VAR)
> +			prev_op = 0;
> +		else
> +			prev_op = 1;
> +	}
> +}
> +
> +static void tst_bool_expr_err(FILE *f, struct tst_expr *expr)
> +{
> +	struct tst_expr *i;
> +	int prev_op = 0;
> +	unsigned int spaces = 0;
> +
> +	fprintf(f, "\n");
> +
> +	for (i = expr; i; i = i->next) {
> +		if (i->err)
> +			break;
> +
> +		if (i->op != TST_OP_VAR && prev_op)
> +			spaces++;
> +
> +		switch (i->op) {
> +		case TST_OP_VAR:
> +			spaces += 2 + strlen(i->val);
> +		break;
> +		default:
> +			spaces++;
> +		}
> +
> +		if (i->op == TST_OP_VAR)
> +			prev_op = 0;
> +		else
> +			prev_op = 1;
> +	}
> +
> +	while (spaces--)
> +		putc(' ', f);
> +
> +	fprintf(f, "^\n");
> +	fprintf(f, "%s\n", i->err);
> +}
> +
> +static inline void stack_push(struct tst_expr *stack[], unsigned int *stack_pos,
> +                              struct tst_expr *op)
> +{
> +	stack[(*stack_pos)++] = op;
> +}
> +
> +static inline int stack_empty(unsigned int stack_pos)
> +{
> +	return stack_pos == 0;
> +}
> +
> +static inline struct tst_expr *stack_pop(struct tst_expr *stack[],
> +                                          unsigned int *stack_pos)
> +{
> +	if (stack_empty(*stack_pos))
> +		return NULL;
> +
> +	return stack[--(*stack_pos)];
> +}
> +
> +static inline enum tst_op stack_top_op(struct tst_expr *stack[],
> +                                       unsigned int stack_pos)

Just a nit, but usually this is called peek, right?

As we are peeking at the top/next entry without removing it.

> +{
> +	if (stack_empty(stack_pos))
> +		return -1;
> +
> +	return stack[stack_pos - 1]->op;
> +}

Perhaps we should copy & paste the dynamic preallocated vector we
created for gfxprim? We are doing a bunch of mallocs and reinventing
linked lists and stacks, which can all be represented by the vector
IIRC.

> +
> +/*
> + * This is a complete list of which tokens can happen before any of:
> + *  - variable
> + *  - left parentesis
> + *  - negation
> + *
> + * The -1 represents start of the expression.

Then it should have an entry in the enum.

> + */
> +static inline int check_one(int op)

I guess there is no good name for this xD

> +{
> +	switch (op) {
> +	case TST_OP_AND:
> +	case TST_OP_OR:
> +	case TST_OP_NOT:
> +	case -1:
> +	case TST_OP_LPAR:
> +		return 0;
> +	default:
> +		return 1;
> +	}
> +}
> +
> +/*
> + * And this checks for tokens that can happen before any of:
> + * - right parentesis
> + * - and
> + * - or
> + *
> + * This is also used to check that the last token in expression is correct one.
> + */
> +static inline int check_two(int op)
> +{
> +	switch (op) {
> +	case TST_OP_VAR:
> +	case TST_OP_RPAR:
> +		return 1;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static struct tst_expr *shunting_yard(struct op_list *list)
> +{

        /* Translator stack */
> +	struct tst_expr *stack[list->cnt];
> +	unsigned int stack_pos = 0;
> +	struct tst_expr *out[list->cnt + 1];
> +	unsigned int out_pos = 0;
> +	struct tst_expr *pars[list->cnt];
> +	unsigned int pars_pos = 0;

It seems we just push stuff to this stack then free everything at the
end?

> +	struct tst_expr *i;
> +	unsigned int j;
> +	int prev_op = -1;

enum tst_op prev_op = TST_OP_START;

> +
> +	for (i = list->first; i; i = i->next) {
> +		switch (i->op) {
> +		case TST_OP_VAR:
> +			if (check_one(prev_op) && prev_op != TST_OP_LPAR) {
> +				i->err = "Expected operation";
> +				goto err;
> +			}
> +
> +			stack_push(out, &out_pos, i);
> +
> +			/* pop all negations */

Clearly :-)

This is not the hardest thing to understand here!

> +			while (stack_top_op(stack, stack_pos) == TST_OP_NOT)
> +				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
> +		break;
> +		case TST_OP_LPAR:
> +			if (check_one(prev_op)) {
> +				i->err = "Expected operation";
> +				goto err;
> +			}
> +
> +			stack_push(stack, &stack_pos, i);
> +		break;
> +		case TST_OP_RPAR:
> +			if (!check_two(prev_op)) {
> +				i->err = "Expected variable or )";
> +				goto err;
> +			}
> +
> +			stack_push(pars, &pars_pos, i);
> +
> +			/* pop everything till ( */
> +			for (;;) {
> +				struct tst_expr *op = stack_pop(stack, &stack_pos);
> +
> +				if (!op) {
> +					i->err = "Missing (";
> +					goto err;
> +				}
> +
> +				if (op->op == TST_OP_LPAR) {
> +					stack_push(pars, &pars_pos, op);
> +					break;
> +				}
> +
> +				stack_push(out, &out_pos, op);
> +			}
> +
> +			/* pop all negations */
> +			while (stack_top_op(stack, stack_pos) == TST_OP_NOT)
> +				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
> +		break;
> +		case TST_OP_NOT:
> +			if (check_one(prev_op)) {
> +				i->err = "Expected operation";
> +				goto err;
> +			}
> +			stack_push(stack, &stack_pos, i);
> +		break;
> +		case TST_OP_AND:
> +		case TST_OP_OR:
> +			if (!check_two(prev_op)) {
> +				i->err = "Expected variable or (";
> +				goto err;
> +			}
> +
> +			/* pop all binary ops */
> +			for (;;) {

It seems that we can only have at most one previous binary op (i.e. '&'
or '|') on the stack before '(' or NULL. Any additional ops after '(' or
NULL are removed.

So the loop can be limited to two iterations and we can assert it never
reaches a third.

> +				enum tst_op top_op;
> +
> +				if (stack_empty(stack_pos))
> +					break;
> +
> +				top_op = stack_top_op(stack, stack_pos);
> +
> +				if (top_op == TST_OP_LPAR ||
> +				    top_op == TST_OP_NOT)
> +					break;

'!'s are removed directly after a variable is seen or a '(' is
removed. So it should be an error to find one on the stack at this
point.

> +
> +				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
> +			}
> +			stack_push(stack, &stack_pos, i);
> +		break;
> +		}
> +
> +		prev_op = i->op;
> +	}
> +
> +	if (!check_two(list->last->op)) {
> +		list->last->err = "Unfinished expression";
> +		goto err;
> +	}
> +
> +	/* pop remaining operations */
> +	while ((i = stack_pop(stack, &stack_pos))) {
> +		if (i->op == TST_OP_LPAR) {
> +			i->err = "Missing )";
> +			goto err;
> +		}
> +
> +		stack_push(out, &out_pos, i);
> +	}
> +
> +	/* free parentesis */
> +	for (j = 0; j < pars_pos; j++)
> +		free(pars[j]);
> +
> +	/* reconstruct the list */
> +	out[out_pos] = NULL;
> +
> +	for (j = 0; j < out_pos; j++)
> +		out[j]->next = out[j + 1];
> +
> +	return out[0];
> +err:
> +	return NULL;
> +}
> +
> +struct tst_expr *tst_bool_expr_parse(const char *expr)
> +{
> +	struct op_list list = {};
> +	struct tst_expr *ret;
> +
> +	tokenize(expr, &list);
> +
> +	if (!list.first)
> +		return NULL;
> +
> +	ret = shunting_yard(&list);
> +
> +	if (!ret) {
> +		tst_bool_expr_print(stderr, list.first);
> +		tst_bool_expr_err(stderr, list.first);
> +		tst_bool_expr_free(list.first);
> +		return NULL;
> +	}
> +
> +	return ret;
> +}
> +
> +#define MAX_STACK 16
> +
> +int tst_bool_expr_eval(struct tst_expr *expr,
> +                       int (*map)(struct tst_expr *var))
> +{
> +	struct tst_expr *i;
> +	int stack[MAX_STACK];
> +	int pos = -1;
> +
> +	for (i = expr; i; i = i->next) {
> +		switch (i->op) {
> +		case TST_OP_NOT:
> +			stack[pos] = !stack[pos];
> +		break;
> +		case TST_OP_OR:
> +			stack[pos-1] = stack[pos] || stack[pos-1];
> +			pos--;
> +		break;
> +		case TST_OP_AND:
> +			stack[pos-1] = stack[pos] && stack[pos-1];
> +			pos--;
> +		break;
> +		case TST_OP_VAR:
> +			if (pos + 1 >= MAX_STACK) {
> +				fprintf(stderr, "Eval out of stack!\n");
> +				return -1;
> +			}
> +
> +			stack[++pos] = map(i);
> +
> +			/* map reported undefined variable -> abort */
> +			if (stack[pos] == -1)
> +				return -1;
> +		break;
> +		/* does not happen */
> +		default:
> +		break;
> +		}
> +	}
> +
> +	return stack[0];
> +}
> +
> +void tst_bool_expr_free(struct tst_expr *expr)
> +{
> +	struct tst_expr *i = expr, *tmp;
> +
> +	while (i) {
> +		tmp = i;
> +		i = i->next;
> +		free(tmp);
> +	}
> +}
> -- 
> 2.26.2

Again, looks really nice!

-- 
Thank you,
Richard.

[LTP] [PATCH 2/3] lib: Add generic boolean expression parser and eval

[Richard Palethorpe]

Hello,

> Cyril Hrubis <chrubis@suse.cz> writes:
>> +
>> +enum tst_op {
>> +	TST_OP_NOT,
>> +	TST_OP_AND,
>> +	TST_OP_OR,
>> +	TST_OP_VAR,
>> +	/* Used only internally */
>> +	TST_OP_LPAR,
>> +	TST_OP_RPAR,
>> +};
>> +
>> +struct tst_expr {
>> +	enum tst_op op;
>> +	struct tst_expr *next;
>> +	char *err;
>> +	void *priv;
>
> I'm not sure if this is used?

I see it, ignore this.
-- 
Thank you,
Richard.

[LTP] [PATCH 2/3] lib: Add generic boolean expression parser and eval

[Cyril Hrubis]

Hi!
> > diff --git a/lib/tst_bool_expr.c b/lib/tst_bool_expr.c
> > new file mode 100644
> > index 000000000..3cb395664
> > --- /dev/null
> > +++ b/lib/tst_bool_expr.c
> > @@ -0,0 +1,504 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Copyright (c) 2020 Cyril Hrubis <chrubis@suse.cz>
> > + */
> > +/*
> > + * Boolean expression is evaluated in three steps.
> > + *
> > + * First of all the string containing the expression is tokenized.
> > + *
> > + * Secondly the the expression is transformed to a postfix (RPN) notation by
> > + * the shunting yard algorithm and the correctness of the expression is checked
> > + * during the transformation as well. The fact that parenthesis are matched is
> > + * asserted by the shunting yard algorithm itself while the rest is checked
> > + * simply by checking if the preceding token is in a set of allowed tokens.
> > + * This could be thought of as a simple open-coded state machine.
> > + *
> > + * An expression in the RPN form can be evaluated given a variable mapping
> > + * function. The evaluation ignores most of errors because invalid expression
> > + * will be rejected in the second step.
> > + */
> > +
> > +#include <string.h>
> > +#include <stdlib.h>
> > +#include <stdio.h>
> > +#include "tst_bool_expr.h"
> > +
> > +#define MAX_TOK 1024
> > +
> > +struct tok {
> > +	unsigned int pos;
> > +	char buf[MAX_TOK];
> 
> Instead we could save an index into the input string here and record the
> length. Then there is no need to copy the string or guess a suitable
> buffer length and we record the original token location for error
> reporting (although it seems you reconstruct the expression so it's not
> so useful).

I guess that this may be easier to work with, I will try to implement
such changes.

> > +enum tst_op char_to_op(char c)
> > +{
> > +	switch (c) {
> > +	case '(':
> > +		return TST_OP_LPAR;
> > +	case ')':
> > +		return TST_OP_RPAR;
> > +	case '&':
> > +		return TST_OP_AND;
> > +	case '|':
> > +		return TST_OP_OR;
> > +	case '!':
> > +		return TST_OP_NOT;
> > +	default:
> > +		return -1;
> 
> This should probably be an enum value like TST_OP_INVAL (still may be
> -1), otherwise it is likely to confuse static anlyses tools.

I tried to avoid adding more enum values since that means that we have
to explicitly handle them in all switch () bodies. So I'm not sure what
is worse, adding nop case to a few of these or having numeric value like
that.

> > +	}
> > +}
> > +
> > +static struct tst_expr *new_op(char c)
> > +{
> > +	struct tst_expr *ret;
> > +
> > +	ret = malloc(sizeof(struct tst_expr));
> > +	if (!ret)
> > +		return NULL;
> > +
> > +	ret->op = char_to_op(c);
> > +	ret->next = NULL;
> > +	ret->err = NULL;
> > +
> > +	return ret;
> > +}
> > +
> > +struct op_list {
> > +	struct tst_expr *first;
> > +	struct tst_expr *last;
> > +	unsigned int cnt;
> > +};
> > +
> > +static void op_list_append(struct op_list *list, struct tst_expr *val)
> > +{
> > +	if (!val)
> > +		return;
> > +
> > +	if (!list->first)
> > +		list->first = val;
> > +
> > +	if (list->last)
> > +		list->last->next = val;
> > +
> > +	list->last = val;
> > +
> > +	list->cnt++;
> > +}
> > +
> > +static void tokenize(const char *expr, struct op_list *ret)
> > +{
> > +	struct tok buf = {};
> > +	size_t i;
> > +
> > +	for (i = 0; expr[i]; i++) {
> > +		switch (expr[i]) {
> > +		case '(':
> > +		case ')':
> > +		case '!':
> > +		case '&':
> > +		case '|':
> > +			op_list_append(ret, new_var(tok_get(&buf)));
> > +			op_list_append(ret, new_op(expr[i]));
> > +		break;
> > +		case '\t':
> > +		case ' ':
> > +			op_list_append(ret, new_var(tok_get(&buf)));
> > +		break;
> > +		default:
> > +			tok_append(&buf, expr[i]);
> > +		break;
> > +		}
> > +	}
> > +
> > +	op_list_append(ret, new_var(tok_get(&buf)));
> > +}
> > +
> > +void tst_bool_expr_print(FILE *f, struct tst_expr *expr)
> > +{
> > +	struct tst_expr *i;
> > +	int prev_op = 0;
> > +
> > +	for (i = expr; i; i = i->next) {
> > +		if (i->op != TST_OP_VAR && prev_op)
> > +			fprintf(f, " ");
> > +
> > +		switch (i->op) {
> > +		case TST_OP_AND:
> > +			fprintf(f, "&");
> > +		break;
> > +		case TST_OP_OR:
> > +			fprintf(f, "|");
> > +		break;
> > +		case TST_OP_NOT:
> > +			fprintf(f, "!");
> > +		break;
> > +		case TST_OP_LPAR:
> > +			fprintf(f, "(");
> > +		break;
> > +		case TST_OP_RPAR:
> > +			fprintf(f, ")");
> > +		break;
> > +		case TST_OP_VAR:
> > +			fprintf(f, " %s ", i->val);
> > +		break;
> > +		}
> > +
> > +		if (i->op == TST_OP_VAR)
> > +			prev_op = 0;
> > +		else
> > +			prev_op = 1;
> > +	}
> > +}
> > +
> > +static void tst_bool_expr_err(FILE *f, struct tst_expr *expr)
> > +{
> > +	struct tst_expr *i;
> > +	int prev_op = 0;
> > +	unsigned int spaces = 0;
> > +
> > +	fprintf(f, "\n");
> > +
> > +	for (i = expr; i; i = i->next) {
> > +		if (i->err)
> > +			break;
> > +
> > +		if (i->op != TST_OP_VAR && prev_op)
> > +			spaces++;
> > +
> > +		switch (i->op) {
> > +		case TST_OP_VAR:
> > +			spaces += 2 + strlen(i->val);
> > +		break;
> > +		default:
> > +			spaces++;
> > +		}
> > +
> > +		if (i->op == TST_OP_VAR)
> > +			prev_op = 0;
> > +		else
> > +			prev_op = 1;
> > +	}
> > +
> > +	while (spaces--)
> > +		putc(' ', f);
> > +
> > +	fprintf(f, "^\n");
> > +	fprintf(f, "%s\n", i->err);
> > +}
> > +
> > +static inline void stack_push(struct tst_expr *stack[], unsigned int *stack_pos,
> > +                              struct tst_expr *op)
> > +{
> > +	stack[(*stack_pos)++] = op;
> > +}
> > +
> > +static inline int stack_empty(unsigned int stack_pos)
> > +{
> > +	return stack_pos == 0;
> > +}
> > +
> > +static inline struct tst_expr *stack_pop(struct tst_expr *stack[],
> > +                                          unsigned int *stack_pos)
> > +{
> > +	if (stack_empty(*stack_pos))
> > +		return NULL;
> > +
> > +	return stack[--(*stack_pos)];
> > +}
> > +
> > +static inline enum tst_op stack_top_op(struct tst_expr *stack[],
> > +                                       unsigned int stack_pos)
> 
> Just a nit, but usually this is called peek, right?
> 
> As we are peeking at the top/next entry without removing it.

I guess that stack_peek_op() may be better name, it has to have the
_op there since we dereference.

> > +{
> > +	if (stack_empty(stack_pos))
> > +		return -1;
> > +
> > +	return stack[stack_pos - 1]->op;
> > +}
> 
> Perhaps we should copy & paste the dynamic preallocated vector we
> created for gfxprim? We are doing a bunch of mallocs and reinventing
> linked lists and stacks, which can all be represented by the vector
> IIRC.

I do not think that it would work for the tokenizer/RPN since we reorder
that and free things from the middle vector is not ideal data structure
for that, link list is better suited for that work. And as for the stack
we use, these have nice upper bound on size so we do not really need
dynamic array for that.

> > +
> > +/*
> > + * This is a complete list of which tokens can happen before any of:
> > + *  - variable
> > + *  - left parentesis
> > + *  - negation
> > + *
> > + * The -1 represents start of the expression.
> 
> Then it should have an entry in the enum.

Same here, if we do that we will end up with nop cases in a few switches
to avoid warnings.

> > + */
> > +static inline int check_one(int op)
> 
> I guess there is no good name for this xD

As far as I can tell no there isn't :-).

> > +{
> > +	switch (op) {
> > +	case TST_OP_AND:
> > +	case TST_OP_OR:
> > +	case TST_OP_NOT:
> > +	case -1:
> > +	case TST_OP_LPAR:
> > +		return 0;
> > +	default:
> > +		return 1;
> > +	}
> > +}
> > +
> > +/*
> > + * And this checks for tokens that can happen before any of:
> > + * - right parentesis
> > + * - and
> > + * - or
> > + *
> > + * This is also used to check that the last token in expression is correct one.
> > + */
> > +static inline int check_two(int op)
> > +{
> > +	switch (op) {
> > +	case TST_OP_VAR:
> > +	case TST_OP_RPAR:
> > +		return 1;
> > +	default:
> > +		return 0;
> > +	}
> > +}
> > +
> > +static struct tst_expr *shunting_yard(struct op_list *list)
> > +{
> 
>         /* Translator stack */
> > +	struct tst_expr *stack[list->cnt];
> > +	unsigned int stack_pos = 0;

Or we can reame this to op_stack[]; I prefer naming variables
reasonably.

> > +	struct tst_expr *out[list->cnt + 1];
> > +	unsigned int out_pos = 0;
> > +	struct tst_expr *pars[list->cnt];
> > +	unsigned int pars_pos = 0;
> 
> It seems we just push stuff to this stack then free everything at the
> end?

Yes, since we eliminate parentesis during the RPN transformation but we
have to free the allocated memory at the end.

> > +	struct tst_expr *i;
> > +	unsigned int j;
> > +	int prev_op = -1;
> 
> enum tst_op prev_op = TST_OP_START;
> 
> > +
> > +	for (i = list->first; i; i = i->next) {
> > +		switch (i->op) {
> > +		case TST_OP_VAR:
> > +			if (check_one(prev_op) && prev_op != TST_OP_LPAR) {
> > +				i->err = "Expected operation";
> > +				goto err;
> > +			}
> > +
> > +			stack_push(out, &out_pos, i);
> > +
> > +			/* pop all negations */
> 
> Clearly :-)
> 
> This is not the hardest thing to understand here!

I guess so, will remove the comment.

Are there any places in the code that are not commented and should be?

> > +			while (stack_top_op(stack, stack_pos) == TST_OP_NOT)
> > +				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
> > +		break;
> > +		case TST_OP_LPAR:
> > +			if (check_one(prev_op)) {
> > +				i->err = "Expected operation";
> > +				goto err;
> > +			}
> > +
> > +			stack_push(stack, &stack_pos, i);
> > +		break;
> > +		case TST_OP_RPAR:
> > +			if (!check_two(prev_op)) {
> > +				i->err = "Expected variable or )";
> > +				goto err;
> > +			}
> > +
> > +			stack_push(pars, &pars_pos, i);
> > +
> > +			/* pop everything till ( */
> > +			for (;;) {
> > +				struct tst_expr *op = stack_pop(stack, &stack_pos);
> > +
> > +				if (!op) {
> > +					i->err = "Missing (";
> > +					goto err;
> > +				}
> > +
> > +				if (op->op == TST_OP_LPAR) {
> > +					stack_push(pars, &pars_pos, op);
> > +					break;
> > +				}
> > +
> > +				stack_push(out, &out_pos, op);
> > +			}
> > +
> > +			/* pop all negations */
> > +			while (stack_top_op(stack, stack_pos) == TST_OP_NOT)
> > +				stack_push(out, &out_pos, stack_pop(stack, &stack_pos));
> > +		break;
> > +		case TST_OP_NOT:
> > +			if (check_one(prev_op)) {
> > +				i->err = "Expected operation";
> > +				goto err;
> > +			}
> > +			stack_push(stack, &stack_pos, i);
> > +		break;
> > +		case TST_OP_AND:
> > +		case TST_OP_OR:
> > +			if (!check_two(prev_op)) {
> > +				i->err = "Expected variable or (";
> > +				goto err;
> > +			}
> > +
> > +			/* pop all binary ops */
> > +			for (;;) {
> 
> It seems that we can only have at most one previous binary op (i.e. '&'
> or '|') on the stack before '(' or NULL. Any additional ops after '(' or
> NULL are removed.
> 
> So the loop can be limited to two iterations and we can assert it never
> reaches a third.
> 
> > +				enum tst_op top_op;
> > +
> > +				if (stack_empty(stack_pos))
> > +					break;
> > +
> > +				top_op = stack_top_op(stack, stack_pos);
> > +
> > +				if (top_op == TST_OP_LPAR ||
> > +				    top_op == TST_OP_NOT)
> > +					break;
> 
> '!'s are removed directly after a variable is seen or a '(' is
> removed. So it should be an error to find one on the stack at this
> point.

I will have a closer look at this two tomorrow, it's quite late in the
evening for me now.

-- 
Cyril Hrubis
chrubis@suse.cz

[LTP] [PATCH 2/3] lib: Add generic boolean expression parser and eval

[Richard Palethorpe]

Hello,

Cyril Hrubis <chrubis@suse.cz> writes:
>
>> > +enum tst_op char_to_op(char c)
>> > +{
>> > +	switch (c) {
>> > +	case '(':
>> > +		return TST_OP_LPAR;
>> > +	case ')':
>> > +		return TST_OP_RPAR;
>> > +	case '&':
>> > +		return TST_OP_AND;
>> > +	case '|':
>> > +		return TST_OP_OR;
>> > +	case '!':
>> > +		return TST_OP_NOT;
>> > +	default:
>> > +		return -1;
>> 
>> This should probably be an enum value like TST_OP_INVAL (still may be
>> -1), otherwise it is likely to confuse static anlyses tools.
>
> I tried to avoid adding more enum values since that means that we have
> to explicitly handle them in all switch () bodies. So I'm not sure what
> is worse, adding nop case to a few of these or having numeric value like
> that.

I think it is usually enough to have a 'default' in the switch statement
to prevent warnings about unhandled values?

Of course there is still a tradeoff here, because you end up with an
enum containing unrelated values.

>
>> > +	}
>> > +}
>> > +
>> > +static struct tst_expr *new_op(char c)
>> > +{
>> > +	struct tst_expr *ret;
>> > +
>> > +	ret = malloc(sizeof(struct tst_expr));
>> > +	if (!ret)
>> > +		return NULL;
>> > +
>> > +	ret->op = char_to_op(c);
>> > +	ret->next = NULL;
>> > +	ret->err = NULL;
>> > +
>> > +	return ret;
>> > +}
>> > +
>> > +struct op_list {
>> > +	struct tst_expr *first;
>> > +	struct tst_expr *last;
>> > +	unsigned int cnt;
>> > +};
>> > +
>> > +static void op_list_append(struct op_list *list, struct tst_expr *val)
>> > +{
>> > +	if (!val)
>> > +		return;
>> > +
>> > +	if (!list->first)
>> > +		list->first = val;
>> > +
>> > +	if (list->last)
>> > +		list->last->next = val;
>> > +
>> > +	list->last = val;
>> > +
>> > +	list->cnt++;
>> > +}
>> > +
>> > +static void tokenize(const char *expr, struct op_list *ret)
>> > +{
>> > +	struct tok buf = {};
>> > +	size_t i;
>> > +
>> > +	for (i = 0; expr[i]; i++) {
>> > +		switch (expr[i]) {
>> > +		case '(':
>> > +		case ')':
>> > +		case '!':
>> > +		case '&':
>> > +		case '|':
>> > +			op_list_append(ret, new_var(tok_get(&buf)));
>> > +			op_list_append(ret, new_op(expr[i]));
>> > +		break;
>> > +		case '\t':
>> > +		case ' ':
>> > +			op_list_append(ret, new_var(tok_get(&buf)));
>> > +		break;
>> > +		default:
>> > +			tok_append(&buf, expr[i]);
>> > +		break;
>> > +		}
>> > +	}
>> > +
>> > +	op_list_append(ret, new_var(tok_get(&buf)));
>> > +}
>> > +
>> > +void tst_bool_expr_print(FILE *f, struct tst_expr *expr)
>> > +{
>> > +	struct tst_expr *i;
>> > +	int prev_op = 0;
>> > +
>> > +	for (i = expr; i; i = i->next) {
>> > +		if (i->op != TST_OP_VAR && prev_op)
>> > +			fprintf(f, " ");
>> > +
>> > +		switch (i->op) {
>> > +		case TST_OP_AND:
>> > +			fprintf(f, "&");
>> > +		break;
>> > +		case TST_OP_OR:
>> > +			fprintf(f, "|");
>> > +		break;
>> > +		case TST_OP_NOT:
>> > +			fprintf(f, "!");
>> > +		break;
>> > +		case TST_OP_LPAR:
>> > +			fprintf(f, "(");
>> > +		break;
>> > +		case TST_OP_RPAR:
>> > +			fprintf(f, ")");
>> > +		break;
>> > +		case TST_OP_VAR:
>> > +			fprintf(f, " %s ", i->val);
>> > +		break;
>> > +		}
>> > +
>> > +		if (i->op == TST_OP_VAR)
>> > +			prev_op = 0;
>> > +		else
>> > +			prev_op = 1;
>> > +	}
>> > +}
>> > +
>> > +static void tst_bool_expr_err(FILE *f, struct tst_expr *expr)
>> > +{
>> > +	struct tst_expr *i;
>> > +	int prev_op = 0;
>> > +	unsigned int spaces = 0;
>> > +
>> > +	fprintf(f, "\n");
>> > +
>> > +	for (i = expr; i; i = i->next) {
>> > +		if (i->err)
>> > +			break;
>> > +
>> > +		if (i->op != TST_OP_VAR && prev_op)
>> > +			spaces++;
>> > +
>> > +		switch (i->op) {
>> > +		case TST_OP_VAR:
>> > +			spaces += 2 + strlen(i->val);
>> > +		break;
>> > +		default:
>> > +			spaces++;
>> > +		}
>> > +
>> > +		if (i->op == TST_OP_VAR)
>> > +			prev_op = 0;
>> > +		else
>> > +			prev_op = 1;
>> > +	}
>> > +
>> > +	while (spaces--)
>> > +		putc(' ', f);
>> > +
>> > +	fprintf(f, "^\n");
>> > +	fprintf(f, "%s\n", i->err);
>> > +}
>> > +
>> > +static inline void stack_push(struct tst_expr *stack[], unsigned int *stack_pos,
>> > +                              struct tst_expr *op)
>> > +{
>> > +	stack[(*stack_pos)++] = op;
>> > +}
>> > +
>> > +static inline int stack_empty(unsigned int stack_pos)
>> > +{
>> > +	return stack_pos == 0;
>> > +}
>> > +
>> > +static inline struct tst_expr *stack_pop(struct tst_expr *stack[],
>> > +                                          unsigned int *stack_pos)
>> > +{
>> > +	if (stack_empty(*stack_pos))
>> > +		return NULL;
>> > +
>> > +	return stack[--(*stack_pos)];
>> > +}
>> > +
>> > +static inline enum tst_op stack_top_op(struct tst_expr *stack[],
>> > +                                       unsigned int stack_pos)
>> 
>> Just a nit, but usually this is called peek, right?
>> 
>> As we are peeking at the top/next entry without removing it.
>
> I guess that stack_peek_op() may be better name, it has to have the
> _op there since we dereference.

+1

>
>> > +{
>> > +	if (stack_empty(stack_pos))
>> > +		return -1;
>> > +
>> > +	return stack[stack_pos - 1]->op;
>> > +}
>> 
>> Perhaps we should copy & paste the dynamic preallocated vector we
>> created for gfxprim? We are doing a bunch of mallocs and reinventing
>> linked lists and stacks, which can all be represented by the vector
>> IIRC.
>
> I do not think that it would work for the tokenizer/RPN since we reorder
> that and free things from the middle vector is not ideal data structure
> for that, link list is better suited for that work. And as for the stack
> we use, these have nice upper bound on size so we do not really need
> dynamic array for that.

Well it is not really about needing it just for this, I'm more thinking
about deduplicating array, stack and list code in general. However I
guess this can be dealt with separately.

>
>> > +
>> > +/*
>> > + * This is a complete list of which tokens can happen before any of:
>> > + *  - variable
>> > + *  - left parentesis
>> > + *  - negation
>> > + *
>> > + * The -1 represents start of the expression.
>> 
>> Then it should have an entry in the enum.
>
> Same here, if we do that we will end up with nop cases in a few switches
> to avoid warnings.
>
>> > + */
>> > +static inline int check_one(int op)
>> 
>> I guess there is no good name for this xD
>
> As far as I can tell no there isn't :-).
>
>> > +{
>> > +	switch (op) {
>> > +	case TST_OP_AND:
>> > +	case TST_OP_OR:
>> > +	case TST_OP_NOT:
>> > +	case -1:
>> > +	case TST_OP_LPAR:
>> > +		return 0;
>> > +	default:
>> > +		return 1;
>> > +	}
>> > +}
>> > +
>> > +/*
>> > + * And this checks for tokens that can happen before any of:
>> > + * - right parentesis
>> > + * - and
>> > + * - or
>> > + *
>> > + * This is also used to check that the last token in expression is correct one.
>> > + */
>> > +static inline int check_two(int op)
>> > +{
>> > +	switch (op) {
>> > +	case TST_OP_VAR:
>> > +	case TST_OP_RPAR:
>> > +		return 1;
>> > +	default:
>> > +		return 0;
>> > +	}
>> > +}
>> > +
>> > +static struct tst_expr *shunting_yard(struct op_list *list)
>> > +{
>> 
>>         /* Translator stack */
>> > +	struct tst_expr *stack[list->cnt];
>> > +	unsigned int stack_pos = 0;
>
> Or we can reame this to op_stack[]; I prefer naming variables
> reasonably.
>
>> > +	struct tst_expr *out[list->cnt + 1];
>> > +	unsigned int out_pos = 0;
>> > +	struct tst_expr *pars[list->cnt];
>> > +	unsigned int pars_pos = 0;
>> 
>> It seems we just push stuff to this stack then free everything at the
>> end?
>
> Yes, since we eliminate parentesis during the RPN transformation but we
> have to free the allocated memory at the end.
>
>> > +	struct tst_expr *i;
>> > +	unsigned int j;
>> > +	int prev_op = -1;
>> 
>> enum tst_op prev_op = TST_OP_START;
>> 
>> > +
>> > +	for (i = list->first; i; i = i->next) {
>> > +		switch (i->op) {
>> > +		case TST_OP_VAR:
>> > +			if (check_one(prev_op) && prev_op != TST_OP_LPAR) {
>> > +				i->err = "Expected operation";
>> > +				goto err;
>> > +			}
>> > +
>> > +			stack_push(out, &out_pos, i);
>> > +
>> > +			/* pop all negations */
>> 
>> Clearly :-)
>> 
>> This is not the hardest thing to understand here!
>
> I guess so, will remove the comment.
>
> Are there any places in the code that are not commented and should be?

I don't think so, unless you have references/links which you think would
be particularly useful for understanding this implementation of the
algorithm?

-- 
Thank you,
Richard.

[LTP] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Richard Palethorpe]

Hello,

Cyril Hrubis <chrubis@suse.cz> writes:

> Hi!
>> >> lines first to remove whitespace issues and expose the parser to all
>> >> possible variable name symbols and values instead of just the ones which
>> >> appear in our current tests.
>> >
>> > I guess that it's techincally possible to have a whitespaces there, but
>> > will not happen unless you hand-edit the config file before compilation,
>> > which I doubt will ever happen.
>> >
>> 
>> It can also happen if someone has their own script to modify the
>> config. At any rate, if you are confident that it will never happen then
>> there should be no problem failing hard if it does.
>
> It would be probably easier to eat the whitespace around the = if
> present. But still I would ignore anything that isn't correct variable
> assignment, since such config would fail kernel compilation anyways.

Works for me :-)

>
>> >> > +			switch (val[0]) {
>> >> > +			case '=':
>> >> > +				break;
>> >> > +			case ' ':
>> >> > +				if (is_set(val, "is not set")) {
>> >> > +					vars[i].choice = 'n';
>> >> > +					return 1;
>> >> > +				}
>> >> 
>> >> Typically such lines begin with a comment '#' and I don't see where that
>> >> is handled. Possibly this will only match non standard configs?
>> >
>> > It does work actually, since we use strstr() to get the "CONFIG_" prefix
>> > from each line of the configuration, but I guess this needs to be fixed
>> > anyways since we would detect "# CONFIG_FOO=y" as enabled config feature
>> > even if it's commented. Again this will not happen unless you hand-edit
>> > the file, but it's probably worth fixing in a follow up patch.
>> 
>> We don't actually use the result of strstr anymore?
>
> Ah right, that's a bug, the cfg should be passed to the
> kconfig_parse_line() instead, at least that's how the previous version
> worked in order to differentiate between unset and unknown variables.
>
>> >> > +				return 1;
>> >> > +			/* vars[i].id may be prefix to longer config var */
>> >> > +			default:
>> >> > +				return 0;
>> >> > +			}
>> >> >  
>> >> > -	if (!cfg)
>> >> > -		return 0;
>> >> > +			if (is_set(val, "=y")) {
>> >> > +				vars[i].choice = 'y';
>> >> > +				return 1;
>> >> > +			}
>> >> >  
>> >> > -	if (strncmp(cfg, conf, match->len))
>> >> > -		return 0;
>> >> > +			if (is_set(val, "=m")) {
>> >> > +				vars[i].choice = 'm';
>> >> > +				return 1;
>> >> > +			}
>> >> >  
>> >> > -	const char *val = &cfg[match->len];
>> >> > +			vars[i].choice = 'v';
>> >> > +			vars[i].val = strndup(val+1, strlen(val)-2);
>> >> >  
>> >> > -	switch (cfg[match->len]) {
>> >> > -	case '=':
>> >> > -		break;
>> >> > -	case ' ':
>> >> > -		if (is_set(val, "is not set")) {
>> >> > -			result->match = 'n';
>> >> > -			goto match;
>> >> > +			return 1;
>> >> >  		}
>> >> > -	/* fall through */
>> >> > -	default:
>> >> > -		return 0;
>> >> > -	}
>> >> > -
>> >> > -	if (is_set(val, "=y")) {
>> >> > -		result->match = 'y';
>> >> > -		goto match;
>> >> >  	}
>> >> >  
>> >> > -	if (is_set(val, "=m")) {
>> >> > -		result->match = 'm';
>> >> > -		goto match;
>> >> > -	}
>> >> > -
>> >> > -	result->match = 'v';
>> >> > -	result->value = strndup(val+1, strlen(val)-2);
>> >> > -
>> >> > -match:
>> >> > -	match->match = 1;
>> >> > -	return 1;
>> >> > +	return 0;
>> >> >  }
>> >> >  
>> >> > -void tst_kconfig_read(const char *const *kconfigs,
>> >> > -                      struct tst_kconfig_res results[], size_t cnt)
>> >> > +void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len)
>> >> >  {
>> >> > -	struct match matches[cnt];
>> >> > -	FILE *fp;
>> >> > -	unsigned int i, j;
>> >> > -	char buf[1024];
>> >> > -
>> >> > -	for (i = 0; i < cnt; i++) {
>> >> > -		const char *val = strchr(kconfigs[i], '=');
>> >> > -
>> >> > -		if (strncmp("CONFIG_", kconfigs[i], 7))
>> >> > -			tst_brk(TBROK, "Invalid config string '%s'", kconfigs[i]);
>> >> > +	char line[128];
>> >> > +	unsigned int vars_found = 0;
>> >> >  
>> >> > -		matches[i].match = 0;
>> >> > -		matches[i].len = strlen(kconfigs[i]);
>> >> > -
>> >> > -		if (val) {
>> >> > -			matches[i].val = val + 1;
>> >> > -			matches[i].len -= strlen(val);
>> >> > -		}
>> >> > -
>> >> > -		results[i].match = 0;
>> >> > -		results[i].value = NULL;
>> >> > -	}
>> >> > -
>> >> > -	fp = open_kconfig();
>> >> > +	FILE *fp = open_kconfig();
>> >> >  	if (!fp)
>> >> >  		tst_brk(TBROK, "Cannot parse kernel .config");
>> >> >  
>> >> > -	while (fgets(buf, sizeof(buf), fp)) {
>> >> > -		for (i = 0; i < cnt; i++) {
>> >> > -			if (match(&matches[i], kconfigs[i], &results[i], buf)) {
>> >> > -				for (j = 0; j < cnt; j++) {
>> >> > -					if (matches[j].match)
>> >> > -						break;
>> >> > -				}
>> >> > +	while (fgets(line, sizeof(line), fp)) {
>> >> > +		char *cfg = strstr(line, "CONFIG_");
>> >> >  
>> >> > -				if (j == cnt)
>> >> > -					goto exit;
>> >> > -			}
>> >> > -		}
>> >> > +		if (!cfg)
>> >> > +			continue;
>> >> 
>> >> This filtering seems unecessary and maybe will hide some corner cases
>> >> because it reduces kconfig_parses_line's exposure. Also practically
>> >> every line has 'CONFIG_' in it.
>> >
>> > Not really, there are empty lines and plenty of comments in the file
>> > generated by kernel infrastructure.
>> 
>> It seems about 80-90% of lines contain CONFIG_, however if you pass it
>> to kconfig_parse_line then this makes more sense. Still I think with
>> proper parsing this shouldn't be there.
>
> What exactly do you mean by a proper parsing?

Tokenize it and remove whitespace.

>
> The file is format is very simple each line starts either with # which
> is a comment or consists of 'key=val' pair and the key is by definition
> prefixed with CONFIG_.
>
>> >> > +
>> >> > +		if (kconfig_parse_line(line, vars, vars_len))
>> >> > +			vars_found++;
>> >> >  
>> >> > +		if (vars_found == vars_len)
>> >> > +			goto exit;
>> >> >  	}
>> >> 
>> >> Generally, this approach seems like to result in spurious TCONFs. We
>> >> need to properly parse the file and fail if some line can't be
>> >> interpreted.
>> >
>> > Well we do expect well formatted .config file from a start, if you hand
>> > edit it and put whitespaces into unexpected places more things may
>> > fail.
>> 
>> Kernel build system seems to have no problem with it. More generally
>> though we should fail hard if there is something unexpected, not produce
>> TCONF which people don't check.
>
> Even if we do I do not think that we should care about anything but
> syntactically correct input, since if you modify the file after kernel
> compilation you have lost anyways.
>
>> >> I suppose most of the problems here stem from the original code, but
>> >> your patch may as well clear it up :-)
>> >
>> > Actually the clear way how to fix this is in a separate patch so that
>> > logical changes are split into different patches.
>> 
>> I suppose that elements of the boolean parser can be used to parse the
>> kconfig and it can be combined (in a later patch). It's kind of
>> unecessary to parse a config file into RPN, but will work perfectly well
>> so we can share some code here.
>
> I do not get what you are trying to say. Are you saying that we should
> tokenize the input? I do not think that this is necessary since the file
> format is pretty simple.

Yes or atleast test the assumption you won't find configs with spaces or
other wierd stuff in by throwing an error if we find something
unexpected. If someone has a broken config we can tell them that.

-- 
Thank you,
Richard.

[LTP] [PATCH 3/3] lib/tst_kconfig: Make use of boolean expression eval

[Richard Palethorpe]

Hello,

I don't see anything obviously wrong here, just some nits.

Cyril Hrubis <chrubis@suse.cz> writes:

> Now each string in the kconfig[] array in tst_test structure is an
> boolean expression which is evaluated. All expressions has to be true in
> order for the test to continue.
>
> + Update the docs.
>
> Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
> CC: Pengfei Xu <pengfei.xu@intel.com>
> ---
>  doc/test-writing-guidelines.txt |  21 ++--
>  lib/newlib_tests/test_kconfig.c |   1 +
>  lib/tst_kconfig.c               | 186 ++++++++++++++++++++++++--------
>  3 files changed, 154 insertions(+), 54 deletions(-)
>
> diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
> index 1a51ef7c7..3c2ab7166 100644
> --- a/doc/test-writing-guidelines.txt
> +++ b/doc/test-writing-guidelines.txt
> @@ -1643,21 +1643,26 @@ on the system, disabled syscalls can be detected by checking for 'ENOSYS'
>  errno etc.
>  
>  However in rare cases core kernel features couldn't be detected based on the
> -kernel userspace API and we have to resort to kernel .config parsing.
> +kernel userspace API and we have to resort to parse the kernel .config.
>  
> -For this cases the test should set the 'NULL' terminated '.needs_kconfigs' array
> -of kernel config options required for the test. The config option can be
> -specified either as plain "CONFIG_FOO" in which case it's sufficient for the
> -test continue if it's set to any value (typically =y or =m). Or with a value
> -as "CONFIG_FOO=bar" in which case the value has to match as well. The test is
> -aborted with 'TCONF' if any of the required options were not set.
> +For this cases the test should set the 'NULL' terminated '.needs_kconfigs'
> +array of boolean expressions with constraints on the kconfig variables. The
> +boolean expression consits of variables, two binary operations '&' and '|',
> +negation '!' and correct sequence of parentesis '()'. Variables are expected
> +to be in a form of "CONFIG_FOO[=bar]".
> +
> +The test will continue to run if all expressions are evaluated to 'True'.
> +Missing variable is mapped to 'False' as well as variable with different than
> +specified value, e.g. 'CONFIG_FOO=bar' will evaluate to 'False' if the value
> +is anything else but 'bar'. If config variable is specified as plain
> +'CONFIG_FOO' it's evaluated to true it's set to any value (typically =y or =m).
>  
>  [source,c]
>  -------------------------------------------------------------------------------
>  #include "tst_test.h"
>  
>  static const char *kconfigs[] = {
> -	"CONFIG_X86_INTEL_UMIP",
> +	"CONFIG_X86_INTEL_UMIP | CONFIG_X86_UMIP",
>  	NULL
>  };
>  
> diff --git a/lib/newlib_tests/test_kconfig.c b/lib/newlib_tests/test_kconfig.c
> index d9c662fc5..183d55611 100644
> --- a/lib/newlib_tests/test_kconfig.c
> +++ b/lib/newlib_tests/test_kconfig.c
> @@ -14,6 +14,7 @@ static const char *kconfigs[] = {
>  	"CONFIG_MMU",
>  	"CONFIG_EXT4_FS=m",
>  	"CONFIG_PGTABLE_LEVELS=4",
> +	"CONFIG_MMU & CONFIG_EXT4_FS=m",
>  	NULL
>  };
>  
> diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
> index f80925cc9..cd99a3034 100644
> --- a/lib/tst_kconfig.c
> +++ b/lib/tst_kconfig.c
> @@ -12,6 +12,7 @@
>  #define TST_NO_DEFAULT_MAIN
>  #include "tst_test.h"
>  #include "tst_kconfig.h"
> +#include "tst_bool_expr.h"
>  
>  static const char *kconfig_path(char *path_buf, size_t path_buf_len)
>  {
> @@ -184,86 +185,179 @@ static size_t array_len(const char *const kconfigs[])
>  	return i;
>  }
>  
> -static int compare_res(struct tst_kconfig_var *var, const char *kconfig,
> -                       char choice, const char *val)
> +static inline unsigned int get_len(const char* kconfig)
>  {
> -	if (var->choice != choice) {
> -		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, var->choice);
> -		return 1;
> -	}
> +	char *sep = index(kconfig, '=');
>  
> -	if (choice != 'v')
> -		return 0;
> +	if (!sep)
> +		return strlen(kconfig);
>  
> -	if (strcmp(var->val, val)) {
> -		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, var->val);
> -		return 1;
> +	return sep - kconfig;
> +}
> +
> +static inline unsigned int get_var_cnt(struct tst_expr *exprs[],

const *?

> +                                       unsigned int expr_cnt)
> +{
> +	unsigned int i;
> +	struct tst_expr *j;
> +	unsigned int cnt = 0;
> +
> +	for (i = 0; i < expr_cnt; i++) {
> +		for (j = exprs[i]; j; j = j->next) {
> +			if (j->op == TST_OP_VAR)
> +				cnt++;
> +		}
>  	}
>  
> -	return 0;
> +	return cnt;
>  }
>  
> -static inline unsigned int get_len(const char* kconfig)
> +static struct tst_kconfig_var *find_var(struct tst_kconfig_var
> vars[],

also const []?

> +                                        unsigned int var_cnt,
> +                                        const char *var)
>  {
> -	char *sep = index(kconfig, '=');
> +	unsigned int i;
>  
> -	if (!sep)
> -		return strlen(kconfig);
> +	for (i = 0; i < var_cnt; i++) {
> +		if (!strcmp(vars[i].id, var))
> +			return &vars[i];
> +	}
>  
> -	return sep - kconfig;
> +	return NULL;
>  }
>  
> -void tst_kconfig_check(const char *const kconfigs[])
> +/*
> + * Fill in the kconfig variables array from the expressions. Also makes sure
> + * that each variable is copied to the array exaclty once.
> + */
> +static inline unsigned int get_vars(struct tst_expr *exprs[],
> +                                    unsigned int expr_cnt,
> +                                    struct tst_kconfig_var vars[])

get_vars sounds like a read-onlyl operation, maybe populate_vars or similar?

>  {
> -	size_t vars_cnt = array_len(kconfigs);
> -	struct tst_kconfig_var vars[vars_cnt];
>  	unsigned int i;
> -	int abort_test = 0;
> +	struct tst_expr *j;
> +	unsigned int cnt = 0;
> +
> +	for (i = 0; i < expr_cnt; i++) {
> +		for (j = exprs[i]; j; j = j->next) {
> +			struct tst_kconfig_var *var;
>  
> -	memset(vars, 0, sizeof(*vars) * vars_cnt);
> +			if (j->op != TST_OP_VAR)
> +				continue;
>  
> -	for (i = 0; i < vars_cnt; i++) {
> -		vars[i].id_len = get_len(kconfigs[i]);
> +			vars[cnt].id_len = get_len(j->val);
>  
> -		if (vars[i].id_len >= sizeof(vars[i].id))
> -			tst_brk(TBROK, "kconfig var id too long!");
> +			if (vars[cnt].id_len >= sizeof(vars[cnt].id))
> +				tst_brk(TBROK, "kconfig var id too long!");
>  
> -		strncpy(vars[i].id, kconfigs[i], vars[i].id_len);
> +			strncpy(vars[cnt].id, j->val, vars[cnt].id_len);
> +
> +			var = find_var(vars, cnt, vars[cnt].id);
> +
> +			if (var)
> +				j->priv = var;
> +			else
> +				j->priv = &vars[cnt++];
> +		}
>  	}
>  
> -	tst_kconfig_read(vars, vars_cnt);
> +	return cnt;
> +}
> +
> +static int map(struct tst_expr *expr)
> +{
> +	struct tst_kconfig_var *var = expr->priv;
>  
> -	for (i = 0; i < vars_cnt; i++) {
> -		if (vars[i].choice == 0) {
> -			tst_res(TINFO, "Missing kernel %s", kconfigs[i]);
> -			abort_test = 1;
> +	if (var->choice == 0)
> +		return 0;
> +
> +	const char *val = strchr(expr->val, '=');
> +
> +	/* CONFIG_FOO evaluates to true if y or m */
> +	if (!val)
> +		return var->choice == 'y' || var->choice == 'm';
> +
> +	char choice = 'v';
> +	val++;
> +
> +	if (!strcmp(val, "n"))
> +		choice = 'n';
> +
> +	if (!strcmp(val, "y"))
> +		choice = 'y';
> +
> +	if (!strcmp(val, "m"))
> +		choice = 'm';
> +
> +	if (choice != 'v')
> +		return var->choice == choice;
> +
> +	return !strcmp(val, var->val);
> +}
> +
> +static void dump_vars(struct tst_expr *expr)

const *?

> +{
> +	struct tst_expr *i;
> +	struct tst_kconfig_var *var;
> +
> +	tst_res(TINFO, "Variables:");
> +
> +	for (i = expr; i; i = i->next) {
> +		if (i->op != TST_OP_VAR)
> +			continue;
> +
> +		var = i->priv;
> +
> +		if (!var->choice) {
> +			tst_res(TINFO, "%s Undefined", var->id);
>  			continue;
>  		}
>  
> -		if (vars[i].choice == 'n') {
> -			tst_res(TINFO, "Kernel %s is not set", kconfigs[i]);
> -			abort_test = 1;
> +		if (var->choice == 'v') {
> +			tst_res(TINFO, "%s = %s", var->id, var->val);
>  			continue;
>  		}
>  
> -		const char *val = strchr(kconfigs[i], '=');
> +		tst_res(TINFO, "%s = %c", var->id, var->choice);
> +	}
> +}
>  
> -		if (val) {
> -			char choice = 'v';
> -			val++;
> +void tst_kconfig_check(const char *const kconfigs[])
> +{
> +	size_t expr_cnt = array_len(kconfigs);
> +	struct tst_expr *exprs[expr_cnt];
> +	unsigned int i, var_cnt;
> +	int abort_test = 0;
> +
> +	for (i = 0; i < expr_cnt; i++) {
> +		exprs[i] = tst_bool_expr_parse(kconfigs[i]);
> +
> +		if (!exprs[i])
> +			tst_brk(TBROK, "Invalid kconfig expression!");
> +	}
>  
> -			if (!strcmp(val, "y"))
> -				choice = 'y';
> +	var_cnt = get_var_cnt(exprs, expr_cnt);
> +	struct tst_kconfig_var vars[var_cnt];
>  
> -			if (!strcmp(val, "m"))
> -				choice = 'm';
> +	var_cnt = get_vars(exprs, expr_cnt, vars);
>  
> -			if (compare_res(&vars[i], kconfigs[i], choice, val))
> -				abort_test = 1;
> +	tst_kconfig_read(vars, var_cnt);
>  
> +	for (i = 0; i < expr_cnt; i++) {
> +		int val = tst_bool_expr_eval(exprs[i], map);
> +
> +		if (val != 1) {
> +			abort_test = 1;
> +			tst_res(TINFO, "Expression '%s' not satisfied!", kconfigs[i]);
> +			dump_vars(exprs[i]);
>  		}
>  
> -		free(vars[i].val);
> +		tst_bool_expr_free(exprs[i]);
> +	}
> +
> +	for (i = 0; i < var_cnt; i++) {
> +		if (vars[i].choice == 'v')
> +			free(vars[i].val);
>  	}
>  
>  	if (abort_test)
> -- 
> 2.26.2


-- 
Thank you,
Richard.

[LTP] [PATCH 1/3] lib/tst_kconfig: Rewrite the parser internals

[Cyril Hrubis]

Hi!
> > I do not get what you are trying to say. Are you saying that we should
> > tokenize the input? I do not think that this is necessary since the file
> > format is pretty simple.
> 
> Yes or atleast test the assumption you won't find configs with spaces or
> other wierd stuff in by throwing an error if we find something
> unexpected. If someone has a broken config we can tell them that.

I guess I can make it a bit more robust in a follow up patch.

-- 
Cyril Hrubis
chrubis@suse.cz

[LTP] [PATCH 2/3] lib: Add generic boolean expression parser and eval

[Cyril Hrubis]

Hi!
> >> > +enum tst_op char_to_op(char c)
> >> > +{
> >> > +	switch (c) {
> >> > +	case '(':
> >> > +		return TST_OP_LPAR;
> >> > +	case ')':
> >> > +		return TST_OP_RPAR;
> >> > +	case '&':
> >> > +		return TST_OP_AND;
> >> > +	case '|':
> >> > +		return TST_OP_OR;
> >> > +	case '!':
> >> > +		return TST_OP_NOT;
> >> > +	default:
> >> > +		return -1;
> >> 
> >> This should probably be an enum value like TST_OP_INVAL (still may be
> >> -1), otherwise it is likely to confuse static anlyses tools.
> >
> > I tried to avoid adding more enum values since that means that we have
> > to explicitly handle them in all switch () bodies. So I'm not sure what
> > is worse, adding nop case to a few of these or having numeric value like
> > that.
> 
> I think it is usually enough to have a 'default' in the switch statement
> to prevent warnings about unhandled values?

That is IMHO wrong as well since this solution defeats the purpose of
the warning in the first place. I do actually like that warning since it
tells me that I have forgotten something.

> Of course there is still a tradeoff here, because you end up with an
> enum containing unrelated values.

And loose the warning as well.

> >> > +{
> >> > +	if (stack_empty(stack_pos))
> >> > +		return -1;
> >> > +
> >> > +	return stack[stack_pos - 1]->op;
> >> > +}
> >> 
> >> Perhaps we should copy & paste the dynamic preallocated vector we
> >> created for gfxprim? We are doing a bunch of mallocs and reinventing
> >> linked lists and stacks, which can all be represented by the vector
> >> IIRC.
> >
> > I do not think that it would work for the tokenizer/RPN since we reorder
> > that and free things from the middle vector is not ideal data structure
> > for that, link list is better suited for that work. And as for the stack
> > we use, these have nice upper bound on size so we do not really need
> > dynamic array for that.
> 
> Well it is not really about needing it just for this, I'm more thinking
> about deduplicating array, stack and list code in general. However I
> guess this can be dealt with separately.

Actually I think that with the token with indexes I can simplify the
code even further and get rid of some.

Thanks for the review I will send a v2 later on.

-- 
Cyril Hrubis
chrubis@suse.cz

[LTP] [PATCH 2/3] lib: Add generic boolean expression parser and eval

[Richard Palethorpe]

Hi,

Cyril Hrubis <chrubis@suse.cz> writes:

> Hi!
>> >> > +enum tst_op char_to_op(char c)
>> >> > +{
>> >> > +	switch (c) {
>> >> > +	case '(':
>> >> > +		return TST_OP_LPAR;
>> >> > +	case ')':
>> >> > +		return TST_OP_RPAR;
>> >> > +	case '&':
>> >> > +		return TST_OP_AND;
>> >> > +	case '|':
>> >> > +		return TST_OP_OR;
>> >> > +	case '!':
>> >> > +		return TST_OP_NOT;
>> >> > +	default:
>> >> > +		return -1;
>> >> 
>> >> This should probably be an enum value like TST_OP_INVAL (still may be
>> >> -1), otherwise it is likely to confuse static anlyses tools.
>> >
>> > I tried to avoid adding more enum values since that means that we have
>> > to explicitly handle them in all switch () bodies. So I'm not sure what
>> > is worse, adding nop case to a few of these or having numeric value like
>> > that.
>> 
>> I think it is usually enough to have a 'default' in the switch statement
>> to prevent warnings about unhandled values?
>
> That is IMHO wrong as well since this solution defeats the purpose of
> the warning in the first place. I do actually like that warning since it
> tells me that I have forgotten something.
>
>> Of course there is still a tradeoff here, because you end up with an
>> enum containing unrelated values.
>
> And loose the warning as well.

This makes sense, but the function still says it returns enum tst_op,
but actually also returns -1. Ideally the function would return a union
of two enums, but I guess C doesn't allow that. At any rate I think you
are correct here. Hopefully at some point I will have chance to try some
more static analyses of LTP.

>
>> >> > +{
>> >> > +	if (stack_empty(stack_pos))
>> >> > +		return -1;
>> >> > +
>> >> > +	return stack[stack_pos - 1]->op;
>> >> > +}
>> >> 
>> >> Perhaps we should copy & paste the dynamic preallocated vector we
>> >> created for gfxprim? We are doing a bunch of mallocs and reinventing
>> >> linked lists and stacks, which can all be represented by the vector
>> >> IIRC.
>> >
>> > I do not think that it would work for the tokenizer/RPN since we reorder
>> > that and free things from the middle vector is not ideal data structure
>> > for that, link list is better suited for that work. And as for the stack
>> > we use, these have nice upper bound on size so we do not really need
>> > dynamic array for that.
>> 
>> Well it is not really about needing it just for this, I'm more thinking
>> about deduplicating array, stack and list code in general. However I
>> guess this can be dealt with separately.
>
> Actually I think that with the token with indexes I can simplify the
> code even further and get rid of some.
>
> Thanks for the review I will send a v2 later on.

+1


-- 
Thank you,
Richard.