fix ITS#3932 - regex/rewrite concurrency issue

libraries/librewrite/rewrite-int.h

@@ -206,6 +206,9 @@ struct rewrite_rule {
 	char                           *lr_pattern;
 	char                           *lr_subststring;
 	char                           *lr_flagstring;
+#ifdef USE_REWRITE_LDAP_PVT_THREADS
+	ldap_pvt_thread_mutex_t         lr_mutex;
+#endif /* USE_REWRITE_LDAP_PVT_THREADS */
 	regex_t                         lr_regex;
 
 	/*

libraries/librewrite/rule.c

@@ -346,6 +346,14 @@ rewrite_rule_compile(
 		return REWRITE_ERR;
 	}
 	
+#ifdef USE_REWRITE_LDAP_PVT_THREADS
+        if ( ldap_pvt_thread_mutex_init( &rule->lr_mutex ) ) {
+		regfree( &rule->lr_regex );
+		free( rule );
+		return REWRITE_ERR;
+	}
+#endif /* USE_REWRITE_LDAP_PVT_THREADS */
+
 	/*
 	 * Just to remember them ...
 	 */
@@ -418,7 +426,15 @@ recurse:;
 			rule->lr_pattern, string, strcnt + 1 );
 	
 	op->lo_num_passes++;
-	if ( regexec( &rule->lr_regex, string, nmatch, match, 0 ) != 0 ) {
+
+#ifdef USE_REWRITE_LDAP_PVT_THREADS
+        ldap_pvt_thread_mutex_lock( &rule->lr_mutex );
+#endif /* USE_REWRITE_LDAP_PVT_THREADS */
+	rc = regexec( &rule->lr_regex, string, nmatch, match, 0 );
+#ifdef USE_REWRITE_LDAP_PVT_THREADS
+        ldap_pvt_thread_mutex_unlock( &rule->lr_mutex );
+#endif /* USE_REWRITE_LDAP_PVT_THREADS */
+	if ( rc != 0 ) {
 		if ( *result == NULL && string != arg ) {
 			free( string );
 		}
@@ -487,6 +503,9 @@ rewrite_rule_destroy(
 	}
 
 	regfree( &rule->lr_regex );
+#ifdef USE_REWRITE_LDAP_PVT_THREADS
+        ldap_pvt_thread_mutex_destroy( &rule->lr_mutex );
+#endif /* USE_REWRITE_LDAP_PVT_THREADS */
 
 	for ( action = rule->lr_action; action; ) {
 		struct rewrite_action *curraction = action;