avformat/wtvdec: Avoid unnecessary allocations

Reviewed-by: Peter Ross <pross@xvid.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/wtvdec.c

@@ -460,71 +460,62 @@ done:
 
 static void get_tag(AVFormatContext *s, AVIOContext *pb, const char *key, int type, int length)
 {
-    int buf_size;
-    char *buf;
+    char buf[LEN_PRETTY_GUID + 1], *bufp = buf;
+    unsigned dict_flags = 0;
 
     if (!strcmp(key, "WM/MediaThumbType")) {
         avio_skip(pb, length);
         return;
     }
 
-    buf_size = FFMIN(FFMAX(length + length / 2U, LEN_PRETTY_GUID) + 1, INT_MAX);
-    buf = av_malloc(buf_size);
-    if (!buf)
-        return;
-
     if (type == 0 && length == 4) {
-        snprintf(buf, buf_size, "%u", avio_rl32(pb));
+        snprintf(buf, sizeof(buf), "%u", avio_rl32(pb));
     } else if (type == 1) {
-        avio_get_str16le(pb, length, buf, buf_size);
-        if (!strlen(buf)) {
-           av_free(buf);
+        int buflen = FFMIN(length + length / 2U + 1, INT_MAX);
+        bufp = av_malloc(buflen);
+        if (!bufp)
+            return;
+        avio_get_str16le(pb, length, bufp, buflen);
+        if (!*bufp) {
+           av_free(bufp);
            return;
         }
+        dict_flags = AV_DICT_DONT_STRDUP_VAL;
     } else if (type == 3 && length == 4) {
         strcpy(buf, avio_rl32(pb) ? "true" : "false");
     } else if (type == 4 && length == 8) {
         int64_t num = avio_rl64(pb);
         if (!strcmp(key, "WM/EncodingTime") ||
             !strcmp(key, "WM/MediaOriginalBroadcastDateTime")) {
-            if (filetime_to_iso8601(buf, buf_size, num) < 0) {
-                av_free(buf);
+            if (filetime_to_iso8601(buf, sizeof(buf), num) < 0)
                 return;
-            }
         } else if (!strcmp(key, "WM/WMRVEncodeTime") ||
                    !strcmp(key, "WM/WMRVEndTime")) {
-            if (crazytime_to_iso8601(buf, buf_size, num) < 0) {
-                av_free(buf);
+            if (crazytime_to_iso8601(buf, sizeof(buf), num) < 0)
                 return;
-            }
         } else if (!strcmp(key, "WM/WMRVExpirationDate")) {
-            if (oledate_to_iso8601(buf, buf_size, num) < 0 ) {
-                av_free(buf);
+            if (oledate_to_iso8601(buf, sizeof(buf), num) < 0)
                 return;
-            }
         } else if (!strcmp(key, "WM/WMRVBitrate"))
-            snprintf(buf, buf_size, "%f", av_int2double(num));
+            snprintf(buf, sizeof(buf), "%f", av_int2double(num));
         else
-            snprintf(buf, buf_size, "%"PRIi64, num);
+            snprintf(buf, sizeof(buf), "%"PRIi64, num);
     } else if (type == 5 && length == 2) {
-        snprintf(buf, buf_size, "%u", avio_rl16(pb));
+        snprintf(buf, sizeof(buf), "%u", avio_rl16(pb));
     } else if (type == 6 && length == 16) {
         ff_asf_guid guid;
         avio_read(pb, guid, 16);
-        snprintf(buf, buf_size, PRI_PRETTY_GUID, ARG_PRETTY_GUID(guid));
+        snprintf(buf, sizeof(buf), PRI_PRETTY_GUID, ARG_PRETTY_GUID(guid));
     } else if (type == 2 && !strcmp(key, "WM/Picture")) {
         get_attachment(s, pb, length);
-        av_freep(&buf);
         return;
     } else {
-        av_freep(&buf);
         av_log(s, AV_LOG_WARNING, "unsupported metadata entry; key:%s, type:%d, length:0x%x\n", key, type, length);
         avio_skip(pb, length);
         return;
     }
 
-    av_dict_set(&s->metadata, key, buf, 0);
-    av_freep(&buf);
+    av_dict_set(&s->metadata, key, bufp, dict_flags);
 }
 
 /**