wtvdec: return error when filetime_to_iso8601/crazytime_to_iso8601 conversion fails

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/wtvdec.c

@@ -368,28 +368,30 @@ static int read_probe(AVProbeData *p)
 
 /**
  * Convert win32 FILETIME to ISO-8601 string
+ * @return <0 on error
  */
-static void filetime_to_iso8601(char *buf, int buf_size, int64_t value)
+static int filetime_to_iso8601(char *buf, int buf_size, int64_t value)
 {
     time_t t = (value / 10000000LL) - 11644473600LL;
     struct tm *tm = gmtime(&t);
-    if (tm)
+    if (!tm)
+        return -1;
     strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", gmtime(&t));
-    else
-        buf[0] = '\0';
+    return 0;
 }
 
 /**
  * Convert crazy time (100ns since 1 Jan 0001) to ISO-8601 string
+ * @return <0 on error
  */
-static void crazytime_to_iso8601(char *buf, int buf_size, int64_t value)
+static int crazytime_to_iso8601(char *buf, int buf_size, int64_t value)
 {
     time_t t = (value / 10000000LL) - 719162LL*86400LL;
     struct tm *tm = gmtime(&t);
-    if (tm)
+    if (!tm)
+        return -1;
     strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", gmtime(&t));
-    else
-        buf[0] = '\0';
+    return 0;
 }
 
 /**
@@ -460,10 +462,16 @@ static void get_tag(AVFormatContext *s, AVIOContext *pb, const char *key, int ty
         int64_t num = avio_rl64(pb);
         if (!strcmp(key, "WM/EncodingTime") ||
             !strcmp(key, "WM/MediaOriginalBroadcastDateTime"))
-            filetime_to_iso8601(buf, buf_size, num);
+            if (filetime_to_iso8601(buf, buf_size, num) < 0) {
+                av_free(buf);
+                return;
+            }
         else if (!strcmp(key, "WM/WMRVEncodeTime") ||
                  !strcmp(key, "WM/WMRVEndTime"))
-            crazytime_to_iso8601(buf, buf_size, num);
+            if (crazytime_to_iso8601(buf, buf_size, num) < 0) {
+                av_free(buf);
+                return;
+            }
         else if (!strcmp(key, "WM/WMRVExpirationDate")) {
             if (oledate_to_iso8601(buf, buf_size, num) < 0 ) {
                 av_free(buf);