MINOR: regex: Copy the original regex expression into string.

This is useful for the debug or for search regex in maps.

include/common/regex.h

@@ -47,6 +47,7 @@ struct my_regex {
 #else /* no PCRE */
 	regex_t regex;
 #endif
+	char *regstr; /* this contain the original string */
 };
 
 /* what to do when a header matches a regex */
@@ -108,6 +109,8 @@ static inline void regex_free(struct my_regex *preg) {
 #else
 	regfree(&preg->regex);
 #endif
+	free(preg->regstr);
+	preg->regstr = NULL;
 }
 
 #endif /* _COMMON_REGEX_H */

src/regex.c

@@ -124,6 +124,13 @@ const char *chain_regex(struct hdr_exp **head, const regex_t *preg,
 
 int regex_comp(const char *str, struct my_regex *regex, int cs, int cap, char **err)
 {
+	/* copy the original regex format */
+	regex->regstr = strdup(str);
+	if (!regex->regstr) {
+		memprintf(err, "out of memory");
+		return 0;
+	}
+
 #ifdef USE_PCRE_JIT
 	int flags = 0;
 	const char *error;
@@ -136,12 +143,14 @@ int regex_comp(const char *str, struct my_regex *regex, int cs, int cap, char **
 
 	regex->reg = pcre_compile(str, flags, &error, &erroffset, NULL);
 	if (!regex->reg) {
+		free(regex->regstr);
 		memprintf(err, "regex '%s' is invalid (error=%s, erroffset=%d)", str, error, erroffset);
 		return 0;
 	}
 
 	regex->extra = pcre_study(regex->reg, PCRE_STUDY_JIT_COMPILE, &error);
 	if (!regex->extra) {
+		free(regex->regstr);
 		pcre_free(regex->reg);
 		memprintf(err, "failed to compile regex '%s' (error=%s)", str, error);
 		return 0;
@@ -155,6 +164,7 @@ int regex_comp(const char *str, struct my_regex *regex, int cs, int cap, char **
 		flags |= REG_NOSUB;
 
 	if (regcomp(&regex->regex, str, flags) != 0) {
+		free(regex->regstr);
 		memprintf(err, "regex '%s' is invalid", str);
 		return 0;
 	}