From 59c6178a54c414fd19e064f0077d00b82a1eb812 Mon Sep 17 00:00:00 2001
From: Justin Ruggles <justin.ruggles@gmail.com>
Date: Thu, 26 Feb 2009 02:29:24 +0000
Subject: Use a shared function to validate FLAC extradata.

Originally committed as revision 17602 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/Makefile  |  7 ++++---
 libavcodec/flac.h    | 16 ++++++++++++++++
 libavcodec/flacdec.c | 47 ++++++++++++++++++++++++++++++++++++++---------
 3 files changed, 58 insertions(+), 12 deletions(-)

(limited to 'libavcodec')

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index afb1ede3fe..afa5fac152 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -345,15 +345,16 @@ OBJS-$(CONFIG_ADPCM_YAMAHA_ENCODER)       += adpcm.o
 
 # libavformat dependencies
 OBJS-$(CONFIG_EAC3_DEMUXER)            += ac3_parser.o ac3tab.o aac_ac3_parser.o
+OBJS-$(CONFIG_FLAC_MUXER)              += flacdec.o
 OBJS-$(CONFIG_GXF_DEMUXER)             += mpeg12data.o
-OBJS-$(CONFIG_MATROSKA_AUDIO_MUXER)    += xiph.o mpeg4audio.o
+OBJS-$(CONFIG_MATROSKA_AUDIO_MUXER)    += xiph.o mpeg4audio.o flacdec.o
 OBJS-$(CONFIG_MATROSKA_DEMUXER)        += mpeg4audio.o
-OBJS-$(CONFIG_MATROSKA_MUXER)          += xiph.o mpeg4audio.o
+OBJS-$(CONFIG_MATROSKA_MUXER)          += xiph.o mpeg4audio.o flacdec.o
 OBJS-$(CONFIG_MOV_DEMUXER)             += mpeg4audio.o mpegaudiodata.o
 OBJS-$(CONFIG_MPEGTS_MUXER)            += mpegvideo.o
 OBJS-$(CONFIG_NUT_MUXER)               += mpegaudiodata.o
 OBJS-$(CONFIG_OGG_DEMUXER)             += flacdec.o
-OBJS-$(CONFIG_OGG_MUXER)               += xiph.o
+OBJS-$(CONFIG_OGG_MUXER)               += xiph.o flacdec.o
 OBJS-$(CONFIG_RTP_MUXER)               += mpegvideo.o
 
 # external codec libraries
diff --git a/libavcodec/flac.h b/libavcodec/flac.h
index 9a4f820831..8af79f2bd8 100644
--- a/libavcodec/flac.h
+++ b/libavcodec/flac.h
@@ -42,6 +42,11 @@ enum {
     FLAC_METADATA_TYPE_INVALID = 127
 };
 
+enum FLACExtradataFormat {
+    FLAC_EXTRADATA_FORMAT_STREAMINFO  = 0,
+    FLAC_EXTRADATA_FORMAT_FULL_HEADER = 1
+};
+
 /**
  * Data needed from the Streaminfo header for use by the raw FLAC demuxer
  * and/or the FLAC decoder.
@@ -68,4 +73,15 @@ typedef struct FLACStreaminfo {
 void ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s,
                               const uint8_t *buffer);
 
+/**
+ * Validate the FLAC extradata.
+ * @param[in]  avctx codec context containing the extradata.
+ * @param[out] format extradata format.
+ * @param[out] streaminfo_start pointer to start of 34-byte STREAMINFO data.
+ * @return 1 if valid, 0 if not valid.
+ */
+int ff_flac_is_extradata_valid(AVCodecContext *avctx,
+                               enum FLACExtradataFormat *format,
+                               uint8_t **streaminfo_start);
+
 #endif /* AVCODEC_FLAC_H */
diff --git a/libavcodec/flacdec.c b/libavcodec/flacdec.c
index d6e0c8620f..42310b24a0 100644
--- a/libavcodec/flacdec.c
+++ b/libavcodec/flacdec.c
@@ -96,26 +96,55 @@ static int64_t get_utf8(GetBitContext *gb)
 }
 
 static void allocate_buffers(FLACContext *s);
-static int metadata_parse(FLACContext *s);
+
+int ff_flac_is_extradata_valid(AVCodecContext *avctx,
+                               enum FLACExtradataFormat *format,
+                               uint8_t **streaminfo_start)
+{
+    if (!avctx->extradata || avctx->extradata_size < FLAC_STREAMINFO_SIZE) {
+        av_log(avctx, AV_LOG_ERROR, "extradata NULL or too small.\n");
+        return 0;
+    }
+    if (AV_RL32(avctx->extradata) != MKTAG('f','L','a','C')) {
+        /* extradata contains STREAMINFO only */
+        if (avctx->extradata_size != FLAC_STREAMINFO_SIZE) {
+            av_log(avctx, AV_LOG_WARNING, "extradata contains %d bytes too many.\n",
+                   FLAC_STREAMINFO_SIZE-avctx->extradata_size);
+        }
+        *format = FLAC_EXTRADATA_FORMAT_STREAMINFO;
+        *streaminfo_start = avctx->extradata;
+    } else {
+        if (avctx->extradata_size < 8+FLAC_STREAMINFO_SIZE) {
+            av_log(avctx, AV_LOG_ERROR, "extradata too small.\n");
+            return 0;
+        }
+        *format = FLAC_EXTRADATA_FORMAT_FULL_HEADER;
+        *streaminfo_start = &avctx->extradata[8];
+    }
+    return 1;
+}
 
 static av_cold int flac_decode_init(AVCodecContext *avctx)
 {
+    enum FLACExtradataFormat format;
+    uint8_t *streaminfo;
     FLACContext *s = avctx->priv_data;
     s->avctx = avctx;
 
     avctx->sample_fmt = SAMPLE_FMT_S16;
 
-    if (avctx->extradata_size > 4) {
+    /* for now, the raw FLAC header is allowed to be passed to the decoder as
+       frame data instead of extradata. */
+    if (!avctx->extradata)
+        return 0;
+
+    if (!ff_flac_is_extradata_valid(avctx, &format, &streaminfo))
+        return -1;
+
         /* initialize based on the demuxer-supplied streamdata header */
-        if (avctx->extradata_size == FLAC_STREAMINFO_SIZE) {
             ff_flac_parse_streaminfo(avctx, (FLACStreaminfo *)s,
-                                     avctx->extradata);
+                                     streaminfo);
             allocate_buffers(s);
-        } else {
-            init_get_bits(&s->gb, avctx->extradata, avctx->extradata_size*8);
-            metadata_parse(s);
-        }
-    }
 
     return 0;
 }
-- 
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