@@ -31,6 +31,10 @@

 #define GCE_DISPOSAL_INPLACE    1

 #define GCE_DISPOSAL_BACKGROUND 2

 #define GCE_DISPOSAL_RESTORE    3

+#define GIF_TRAILER                 0x3b

+#define GIF_EXTENSION_INTRODUCER    0x21

+#define GIF_IMAGE_SEPARATOR         0x2c

+#define GIF_GCE_EXT_LABEL           0xf9

 typedef struct GifState {

     AVFrame picture;

@@ -170,7 +174,7 @@ static int gif_read_extension(GifState *s)

     av_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);

     switch(ext_code) {

-    case 0xf9:

+    case GIF_GCE_EXT_LABEL:

         if (ext_len != 4)

             goto discard_ext;

         s->transparent_color_index = -1;

@@ -248,28 +252,32 @@ static int gif_read_header1(GifState *s)

     return 0;

 }

-static int gif_parse_next_image(GifState *s)

+static int gif_parse_next_image(GifState *s, int *got_picture)

 {

+    int ret;

+    *got_picture = sizeof(AVPicture);

     while (s->bytestream < s->bytestream_end) {

         int code = bytestream_get_byte(&s->bytestream);

         av_dlog(s->avctx, "code=%02x '%c'\n", code, code);

         switch (code) {

-        case ',':

+        case GIF_IMAGE_SEPARATOR:

             return gif_read_image(s);

-        case '!':

-            if (gif_read_extension(s) < 0)

-                return -1;

+        case GIF_EXTENSION_INTRODUCER:

+            if ((ret = gif_read_extension(s)) < 0)

+                return ret;

             break;

-        case ';':

+        case GIF_TRAILER:

             /* end of image */

+            *got_picture = 0;

+            return 0;

         default:

-            /* error or erroneous EOF */

-            return -1;

+            /* erroneous block label */

+            return AVERROR_INVALIDDATA;

         }

     }

-    return -1;

+    return AVERROR_EOF;

 }

 static av_cold int gif_decode_init(AVCodecContext *avctx)

@@ -285,7 +293,7 @@ static av_cold int gif_decode_init(AVCodecContext *avctx)

     return 0;

 }

-static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)

+static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_picture, AVPacket *avpkt)

 {

     const uint8_t *buf = avpkt->data;

     int buf_size = avpkt->size;

@@ -299,8 +307,8 @@ static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, A

         return ret;

     avctx->pix_fmt = AV_PIX_FMT_PAL8;

-    if (av_image_check_size(s->screen_width, s->screen_height, 0, avctx))

-        return -1;

+    if ((ret = av_image_check_size(s->screen_width, s->screen_height, 0, avctx)) < 0)

+        return ret;

     avcodec_set_dimensions(avctx, s->screen_width, s->screen_height);

     if (s->picture.data[0])

@@ -310,12 +318,12 @@ static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, A

         return ret;

     }

     s->image_palette = (uint32_t *)s->picture.data[1];

-    ret = gif_parse_next_image(s);

+    ret = gif_parse_next_image(s, got_picture);

     if (ret < 0)

         return ret;

+    else if (*got_picture)

+        *picture = s->picture;

-    *picture = s->picture;

-    *data_size = sizeof(AVPicture);

     return s->bytestream - buf;

 }