[PATCH v2 4/5] libmultipath: config parser: fix corner case for double quotes

[Martin Wilck <mwilck@suse.com>]

A corner case of the previous patch are strings starting with a double quote,
such as '"prepended to itself is false" prepended to itself is false' or
'"" is the empty string', and in particular, the string '"' ("\"" in C
notation), which is indistinguishable from the "QUOTE" token in the parsed strvec.

This patch fixes that by introducing a special token that can't occur as part
of a normal string to indicate the beginning and end of a quoted string.

'"' is admittedly not a very likely keyword value for multipath.conf, but
a) this is a matter of correctness, b) we didn't think of '2.5"' before, either, and
c) the (*str != '"') expressions would need to be patched anyway to fix the
'string starting with "' case.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 libmultipath/parser.c | 31 ++++++++++++++++++-------------
 libmultipath/parser.h |  1 +
 multipathd/cli.c      |  2 +-
 tests/parser.c        |  5 -----
 4 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/libmultipath/parser.c b/libmultipath/parser.c
index 21151a16ad74..cee1c9681361 100644
--- a/libmultipath/parser.c
+++ b/libmultipath/parser.c
@@ -186,6 +186,12 @@ snprint_keyword(char *buff, int len, char *fmt, struct keyword *kw,
 	return fwd;
 }
 
+static const char quote_marker[] = { '\0', '"', '\0' };
+bool is_quote(const char* token)
+{
+	return !memcmp(token, quote_marker, sizeof(quote_marker));
+}
+
 vector
 alloc_strvec(char *string)
 {
@@ -227,13 +233,12 @@ alloc_strvec(char *string)
 		start = cp;
 		if (*cp == '"' && !(in_string && *(cp + 1) == '"')) {
 			cp++;
-			token = MALLOC(2);
+			token = MALLOC(sizeof(quote_marker));
 
 			if (!token)
 				goto out;
 
-			*(token) = '"';
-			*(token + 1) = '\0';
+			memcpy(token, quote_marker, sizeof(quote_marker));
 			if (in_string)
 				in_string = 0;
 			else
@@ -324,13 +329,13 @@ set_value(vector strvec)
 			(char *)VECTOR_SLOT(strvec, 0));
 		return NULL;
 	}
-	size = strlen(str);
-	if (size == 0) {
-		condlog(0, "option '%s' has empty value",
-			(char *)VECTOR_SLOT(strvec, 0));
-		return NULL;
-	}
-	if (*str != '"') {
+	if (!is_quote(str)) {
+		size = strlen(str);
+		if (size == 0) {
+			condlog(0, "option '%s' has empty value",
+				(char *)VECTOR_SLOT(strvec, 0));
+			return NULL;
+		}
 		alloc = MALLOC(sizeof (char) * (size + 1));
 		if (alloc)
 			memcpy(alloc, str, size);
@@ -354,7 +359,7 @@ set_value(vector strvec)
 				(char *)VECTOR_SLOT(strvec, 0));
 			return NULL;
 		}
-		if (*str == '"')
+		if (is_quote(str))
 			break;
 		tmp = alloc;
 		/* The first +1 is for the NULL byte. The rest are for the
@@ -460,7 +465,7 @@ validate_config_strvec(vector strvec, char *file)
 			(char *)VECTOR_SLOT(strvec, 0), line_nr, file);
 		return -1;
 	}
-	if (*str != '"') {
+	if (!is_quote(str)) {
 		if (VECTOR_SIZE(strvec) > 2)
 			condlog(0, "ignoring extra data starting with '%s' on line %d of %s", (char *)VECTOR_SLOT(strvec, 2), line_nr, file);
 		return 0;
@@ -472,7 +477,7 @@ validate_config_strvec(vector strvec, char *file)
 				line_nr, file);
 			return -1;
 		}
-		if (*str == '"') {
+		if (is_quote(str)) {
 			if (VECTOR_SIZE(strvec) > i + 1)
 				condlog(0, "ignoring extra data starting with '%s' on line %d of %s", (char *)VECTOR_SLOT(strvec, (i + 1)), line_nr, file);
 			return 0;
diff --git a/libmultipath/parser.h b/libmultipath/parser.h
index 0a747507d7be..62906e98c1f7 100644
--- a/libmultipath/parser.h
+++ b/libmultipath/parser.h
@@ -81,5 +81,6 @@ extern int process_file(struct config *conf, char *conf_file);
 extern struct keyword * find_keyword(vector keywords, vector v, char * name);
 int snprint_keyword(char *buff, int len, char *fmt, struct keyword *kw,
 		    const void *data);
+bool is_quote(const char* token);
 
 #endif
diff --git a/multipathd/cli.c b/multipathd/cli.c
index f10f862cd14f..bf25b41fd5dd 100644
--- a/multipathd/cli.c
+++ b/multipathd/cli.c
@@ -279,7 +279,7 @@ get_cmdvec (char * cmd, vector *v)
 	}
 
 	vector_foreach_slot(strvec, buff, i) {
-		if (*buff == '"')
+		if (is_quote(buff))
 			continue;
 		if (get_param) {
 			get_param = 0;
diff --git a/tests/parser.c b/tests/parser.c
index 8e73cebd878a..a7e759838495 100644
--- a/tests/parser.c
+++ b/tests/parser.c
@@ -34,11 +34,6 @@
 /* Stop parsing at 2nd quote */
 #define TWO_QUOTES_ONLY 0
 
-static bool is_quote(const char *s)
-{
-	return *s == '"';
-}
-
 static char *test_file = "test.conf";
 
 /* Missing declaration */
-- 
2.16.1