thread-safe version of strerror_r now, still missing tests

1 files changed, 14 insertions, 3 deletions

diff --git a/src/port/string.c b/src/port/string.c
index da0dfce..83b1daa 100644
--- a/src/port/string.c
+++ b/src/port/string.c
@@ -44,16 +44,25 @@ char *wolf_port_strdup( const char *s ) {
 #if !defined HAVE_STRERROR_R || defined TEST_STRERROR_R
 
 #include "port/stdio.h"		/* for snprintf */
+#include "port/stdbool.h"	/* for bool */
 #include <sys/types.h>		/* for size_t */
 #include <errno.h>		/* for errno */
+#include "mutex.h"		/* for mutexes */
+
+static bool mutex_initialized = false;
+static wolf_mutex_t mutex;
 
-/* FIXME: this version is NOT thread and signal safe! But we have to port
- * mutexes first
- */
 int wolf_port_strerror_r( int num, char *buf, size_t buflen ) {
 	int safe_errno = errno;
 	const char *msg;
 
+	/* critical section as strerror is not thread-safe */
+	if( !mutex_initialized ) {
+		wolf_mutex_init( &mutex );
+		mutex_initialized = true;
+	}
+	wolf_mutex_lock( &mutex );
+
 	msg = strerror( num );
 	/* TODO: can we detect illegal error numbers? For sure on Linux NULL
 	 * is never returned and a strcmp with prefix "Unknown error" or similar
@@ -64,11 +73,13 @@ int wolf_port_strerror_r( int num, char *buf, size_t buflen ) {
 		/* Linux returns an empty string in this case, why? */
 		(void)snprintf( buf, buflen, "Unknown error %d", num );
 		errno = EINVAL;
+		wolf_mutex_unlock( &mutex );
 		return -1;
 	}
 
 	strncpy( buf, msg, buflen-1 );
 	errno = safe_errno;
+	wolf_mutex_unlock( &mutex );
 	return 0;
 }