CD+G demuxer and decoder

[ffmpeg] / libavcodec / gifdec.c

diff --git a/libavcodec/gifdec.c b/libavcodec/gifdec.c
index 64b49313549446edf3e7d3517732b2d848b903fd..70da4e2a57c3af8757a36ab9478351cb236178ba 100644 (file)
--- a/libavcodec/gifdec.c
+++ b/libavcodec/gifdec.c
@@ -1,7 +1,7 @@
 /*
  * GIF decoder
- * Copyright (c) 2003 Fabrice Bellard.
- * Copyright (c) 2006 Baptiste Coudurier.
+ * Copyright (c) 2003 Fabrice Bellard
+ * Copyright (c) 2006 Baptiste Coudurier
  *
  * This file is part of FFmpeg.
  *
@@ -47,7 +47,8 @@ typedef struct GifState {
     int gce_delay;
 
     /* LZW compatible decoder */
-    uint8_t *bytestream;
+    const uint8_t *bytestream;
+    const uint8_t *bytestream_end;
     LZWState *lzw;
 
     /* aux buffers */
@@ -95,8 +96,7 @@ static int gif_read_image(GifState *s)
     n = (1 << bits_per_pixel);
     spal = palette;
     for(i = 0; i < n; i++) {
-        s->image_palette[i] = (0xff << 24) |
-            (spal[0] << 16) | (spal[1] << 8) | (spal[2]);
+        s->image_palette[i] = (0xff << 24) | AV_RB24(spal);
         spal += 3;
     }
     for(; i < 256; i++)
@@ -107,8 +107,8 @@ static int gif_read_image(GifState *s)
 
     /* now get the image data */
     code_size = bytestream_get_byte(&s->bytestream);
-    //TODO: add proper data size
-    ff_lzw_decode_init(s->lzw, code_size, s->bytestream, 0, FF_LZW_GIF);
+    ff_lzw_decode_init(s->lzw, code_size, s->bytestream,
+                       s->bytestream_end - s->bytestream, FF_LZW_GIF);
 
     /* read all the image */
     linesize = s->picture.linesize[0];
@@ -126,11 +126,8 @@ static int gif_read_image(GifState *s)
                 y1 += 8;
                 ptr += linesize * 8;
                 if (y1 >= height) {
-                    y1 = 4;
-                    if (pass == 0)
-                        ptr = ptr1 + linesize * 4;
-                    else
-                        ptr = ptr1 + linesize * 2;
+                    y1 = pass ? 2 : 4;
+                    ptr = ptr1 + linesize * y1;
                     pass++;
                 }
                 break;
@@ -209,6 +206,9 @@ static int gif_read_header1(GifState *s)
     int v, n;
     int has_global_palette;
 
+    if (s->bytestream_end < s->bytestream + 13)
+        return -1;
+
     /* read gif signature */
     bytestream_get_buffer(&s->bytestream, sig, 6);
     if (memcmp(sig, gif87a_sig, 6) != 0 &&
@@ -238,6 +238,8 @@ static int gif_read_header1(GifState *s)
 #endif
     if (has_global_palette) {
         n = 1 << s->bits_per_pixel;
+        if (s->bytestream_end < s->bytestream + n * 3)
+            return -1;
         bytestream_get_buffer(&s->bytestream, s->global_palette, n * 3);
     }
     return 0;
@@ -245,39 +247,29 @@ static int gif_read_header1(GifState *s)
 
 static int gif_parse_next_image(GifState *s)
 {
-    int ret, code;
-
-    for (;;) {
-        code = bytestream_get_byte(&s->bytestream);
+    while (s->bytestream < s->bytestream_end) {
+        int code = bytestream_get_byte(&s->bytestream);
 #ifdef DEBUG
         dprintf(s->avctx, "gif: code=%02x '%c'\n", code, code);
 #endif
         switch (code) {
         case ',':
-            if (gif_read_image(s) < 0)
-                return -1;
-            ret = 0;
-            goto the_end;
-        case ';':
-            /* end of image */
-            ret = -1;
-            goto the_end;
+            return gif_read_image(s);
         case '!':
             if (gif_read_extension(s) < 0)
                 return -1;
             break;
-        case EOF:
+        case ';':
+            /* end of image */
         default:
-            /* error or errneous EOF */
-            ret = -1;
-            goto the_end;
+            /* error or erroneous EOF */
+            return -1;
         }
     }
-  the_end:
-    return ret;
+    return -1;
 }
 
-static int gif_decode_init(AVCodecContext *avctx)
+static av_cold int gif_decode_init(AVCodecContext *avctx)
 {
     GifState *s = avctx->priv_data;
 
@@ -290,13 +282,16 @@ static int gif_decode_init(AVCodecContext *avctx)
     return 0;
 }
 
-static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
+static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
 {
+    const uint8_t *buf = avpkt->data;
+    int buf_size = avpkt->size;
     GifState *s = avctx->priv_data;
     AVFrame *picture = data;
     int ret;
 
     s->bytestream = buf;
+    s->bytestream_end = buf + buf_size;
     if (gif_read_header1(s) < 0)
         return -1;
 
@@ -318,10 +313,10 @@ static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, u
 
     *picture = s->picture;
     *data_size = sizeof(AVPicture);
-    return 0;
+    return s->bytestream - buf;
 }
 
-static int gif_decode_close(AVCodecContext *avctx)
+static av_cold int gif_decode_close(AVCodecContext *avctx)
 {
     GifState *s = avctx->priv_data;
 
@@ -340,4 +335,6 @@ AVCodec gif_decoder = {
     NULL,
     gif_decode_close,
     gif_decode_frame,
+    CODEC_CAP_DR1,
+    .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
 };