[PATCH v2] add a flag to supress errors in git_config_parse_key()

[Tanay Abhra <tanayabh@gmail.com>]

`git_config_parse_key()` is used to sanitize the input key.
Some callers of the function like `git_config_set_multivar_in_file()`
get the pre-sanitized key directly from the user so it becomes
necessary to raise an error specifying what went wrong when the entered
key is syntactically malformed.

Other callers like `configset_find_element()` get their keys from
the git itself so a return value signifying error would be enough.
The error output shown to the user is useless and confusing in this
case so add a flag to suppress errors in such cases.

Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
---
Hi Jeff,

I went through Junio's config guideline patch series
and the whole thread of underscore bug report and I also think
that pager.*.command is the right path to go.

If you want to relax the syntactic requirement (such as add '_' to
the current set of allowed chacters), I can work upon it but most of the
comments point that moving towards pager.*.command would be better.

p.s: I hope that I got the unsigned flag suggestion by Junio correctly.

-Tanay

 builtin/config.c |  2 +-
 cache.h          |  4 +++-
 config.c         | 20 +++++++++++++-------
 t/t7006-pager.sh |  9 +++++++++
 4 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/builtin/config.c b/builtin/config.c
index d32c532..326d3d3 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -200,7 +200,7 @@ static int get_value(const char *key_, const char *regex_)
 			goto free_strings;
 		}
 	} else {
-		if (git_config_parse_key(key_, &key, NULL)) {
+		if (git_config_parse_key(key_, &key, NULL, 0)) {
 			ret = CONFIG_INVALID_KEY;
 			goto free_strings;
 		}
diff --git a/cache.h b/cache.h
index f704af5..9073ee2 100644
--- a/cache.h
+++ b/cache.h
@@ -1329,6 +1329,8 @@ extern int update_server_info(int);

 #define CONFIG_REGEX_NONE ((void *)1)

+#define CONFIG_ERROR_QUIET 0x0001
+
 struct git_config_source {
 	unsigned int use_stdin:1;
 	const char *file;
@@ -1358,7 +1360,7 @@ extern int git_config_string(const char **, const char *, const char *);
 extern int git_config_pathname(const char **, const char *, const char *);
 extern int git_config_set_in_file(const char *, const char *, const char *);
 extern int git_config_set(const char *, const char *);
-extern int git_config_parse_key(const char *, char **, int *);
+extern int git_config_parse_key(const char *, char **, int *, unsigned int);
 extern int git_config_set_multivar(const char *, const char *, const char *, int);
 extern int git_config_set_multivar_in_file(const char *, const char *, const char *, const char *, int);
 extern int git_config_rename_section(const char *, const char *);
diff --git a/config.c b/config.c
index e5e64dc..7e23bb9 100644
--- a/config.c
+++ b/config.c
@@ -1309,7 +1309,7 @@ static struct config_set_element *configset_find_element(struct config_set *cs,
 	 * `key` may come from the user, so normalize it before using it
 	 * for querying entries from the hashmap.
 	 */
-	ret = git_config_parse_key(key, &normalized_key, NULL);
+	ret = git_config_parse_key(key, &normalized_key, NULL, CONFIG_ERROR_QUIET);

 	if (ret)
 		return NULL;
@@ -1842,8 +1842,10 @@ int git_config_set(const char *key, const char *value)
  *             lowercase section and variable name
  * baselen - pointer to int which will hold the length of the
  *           section + subsection part, can be NULL
+ * flags - toggle whether the function raises an error on a syntactically
+ *         malformed key
  */
-int git_config_parse_key(const char *key, char **store_key, int *baselen_)
+int git_config_parse_key(const char *key, char **store_key, int *baselen_, unsigned int flags)
 {
 	int i, dot, baselen;
 	const char *last_dot = strrchr(key, '.');
@@ -1854,12 +1856,14 @@ int git_config_parse_key(const char *key, char **store_key, int *baselen_)
 	 */

 	if (last_dot == NULL || last_dot == key) {
-		error("key does not contain a section: %s", key);
+		if (!flags)
+			error("key does not contain a section: %s", key);
 		return -CONFIG_NO_SECTION_OR_NAME;
 	}

 	if (!last_dot[1]) {
-		error("key does not contain variable name: %s", key);
+		if (!flags)
+			error("key does not contain variable name: %s", key);
 		return -CONFIG_NO_SECTION_OR_NAME;
 	}

@@ -1881,12 +1885,14 @@ int git_config_parse_key(const char *key, char **store_key, int *baselen_)
 		if (!dot || i > baselen) {
 			if (!iskeychar(c) ||
 			    (i == baselen + 1 && !isalpha(c))) {
-				error("invalid key: %s", key);
+				if (!flags)
+					error("invalid key: %s", key);
 				goto out_free_ret_1;
 			}
 			c = tolower(c);
 		} else if (c == '\n') {
-			error("invalid key (newline): %s", key);
+			if (!flags)
+				error("invalid key (newline): %s", key);
 			goto out_free_ret_1;
 		}
 		(*store_key)[i] = c;
@@ -1936,7 +1942,7 @@ int git_config_set_multivar_in_file(const char *config_filename,
 	char *filename_buf = NULL;

 	/* parse-key returns negative; flip the sign to feed exit(3) */
-	ret = 0 - git_config_parse_key(key, &store.key, &store.baselen);
+	ret = 0 - git_config_parse_key(key, &store.key, &store.baselen, 0);
 	if (ret)
 		goto out_free;

diff --git a/t/t7006-pager.sh b/t/t7006-pager.sh
index da958a8..2dd71c0 100755
--- a/t/t7006-pager.sh
+++ b/t/t7006-pager.sh
@@ -447,4 +447,13 @@ test_expect_success TTY 'external command pagers override sub-commands' '
 	test_cmp expect actual
 '

+test_expect_success 'command with underscores does not complain' '
+	write_script git-under_score <<-\EOF &&
+	echo ok
+	EOF
+	git --exec-path=. under_score >actual 2>&1 &&
+	echo ok >expect &&
+	test_cmp expect actual
+'
+
 test_done
-- 
1.9.0.GIT