Merge commit '30db94dc399f6e4ef8905049d9b740556f0fce47'

* commit '30db94dc399f6e4ef8905049d9b740556f0fce47':
  xan: Use bytestream2 to limit reading to within the buffer

Conflicts:
	libavcodec/xan.c

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

libavcodec/xan.c

@@ -300,10 +300,9 @@ static int xan_wc3_decode_frame(XanContext *s, AVFrame *frame)
 
     /* pointers to segments inside the compressed chunk */
     const uint8_t *huffman_segment;
-    const uint8_t *size_segment;
-    const uint8_t *vector_segment;
+    GetByteContext       size_segment;
+    GetByteContext       vector_segment;
     const uint8_t *imagedata_segment;
-    const uint8_t *buf_end = s->buf + s->size;
     int huffman_offset, size_offset, vector_offset, imagedata_offset,
         imagedata_size;
 
@@ -322,8 +321,8 @@ static int xan_wc3_decode_frame(XanContext *s, AVFrame *frame)
         return AVERROR_INVALIDDATA;
 
     huffman_segment   = s->buf + huffman_offset;
-    size_segment      = s->buf + size_offset;
-    vector_segment    = s->buf + vector_offset;
+    bytestream2_init(&size_segment,   s->buf + size_offset,   s->size - size_offset);
+    bytestream2_init(&vector_segment, s->buf + vector_offset, s->size - vector_offset);
     imagedata_segment = s->buf + imagedata_offset;
 
     if (xan_huffman_decode(opcode_buffer, opcode_buffer_size,
@@ -375,31 +374,29 @@ static int xan_wc3_decode_frame(XanContext *s, AVFrame *frame)
 
         case 9:
         case 19:
-            if (buf_end - size_segment < 1) {
+            if (bytestream2_get_bytes_left(&size_segment) < 1) {
                 av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }
-            size = *size_segment++;
+            size = bytestream2_get_byte(&size_segment);
             break;
 
         case 10:
         case 20:
-            if (buf_end - size_segment < 2) {
+            if (bytestream2_get_bytes_left(&size_segment) < 2) {
                 av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }
-            size = AV_RB16(&size_segment[0]);
-            size_segment += 2;
+            size = bytestream2_get_be16(&size_segment);
             break;
 
         case 11:
         case 21:
-            if (buf_end - size_segment < 3) {
+            if (bytestream2_get_bytes_left(&size_segment) < 3) {
                 av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }
-            size = AV_RB24(size_segment);
-            size_segment += 3;
+            size = bytestream2_get_be24(&size_segment);
             break;
         }
 
@@ -420,14 +417,15 @@ static int xan_wc3_decode_frame(XanContext *s, AVFrame *frame)
                 imagedata_size -= size;
             }
         } else {
-            if (vector_segment >= buf_end) {
+            uint8_t vector;
+            if (bytestream2_get_bytes_left(&vector_segment) <= 0) {
                 av_log(s->avctx, AV_LOG_ERROR, "vector_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }
             /* run-based motion compensation from last frame */
-            motion_x = sign_extend(*vector_segment >> 4,  4);
-            motion_y = sign_extend(*vector_segment & 0xF, 4);
-            vector_segment++;
+            vector = bytestream2_get_byte(&vector_segment);
+            motion_x = sign_extend(vector >> 4,  4);
+            motion_y = sign_extend(vector & 0xF, 4);
 
             /* copy a run of pixels from the previous frame */
             xan_wc3_copy_pixel_run(s, frame, x, y, size, motion_x, motion_y);