avformat/vividas: Avoid allocation of AVIOContext

Put an AVIOContext whose lifetime doesn't extend beyond the function where
it is allocated on the stack instead of allocating and freeing it. This
also avoids the need to free it, which in this case fixes possible
memleaks on error.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/vividas.c

@@ -282,11 +282,9 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *
     int64_t off;
     int val_1;
     int num_video;
-    AVIOContext *pb;
+    AVIOContext pb0, *pb = &pb0;
 
-    pb = avio_alloc_context(buf, size, 0, NULL, NULL, NULL, NULL);
-    if (!pb)
-        return AVERROR(ENOMEM);
+    ffio_init_context(pb, buf, size, 0, NULL, NULL, NULL, NULL);
 
     ffio_read_varlen(pb); // track_header_len
     avio_r8(pb); // '1'
@@ -383,7 +381,6 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *
             for (j = 0; j < num_data; j++) {
                 uint64_t len = ffio_read_varlen(pb);
                 if (len > INT_MAX/2 - xd_size) {
-                    av_free(pb);
                     return AVERROR_INVALIDDATA;
                 }
                 data_len[j] = len;
@@ -392,7 +389,6 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *
 
             st->codecpar->extradata_size = 64 + xd_size + xd_size / 255;
             if (ff_alloc_extradata(st->codecpar, st->codecpar->extradata_size)) {
-                av_free(pb);
                 return AVERROR(ENOMEM);
             }
 
@@ -402,7 +398,6 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *
             for (j = 0; j < num_data - 1; j++) {
                 unsigned delta = av_xiphlacing(&p[offset], data_len[j]);
                 if (delta > data_len[j]) {
-                    av_free(pb);
                     return AVERROR_INVALIDDATA;
                 }
                 offset += delta;
@@ -423,7 +418,6 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *
         }
     }
 
-    av_free(pb);
     return 0;
 }
 
@@ -432,13 +426,11 @@ static int track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *bu
     int64_t off;
     int64_t poff;
     int maxnp=0;
-    AVIOContext *pb;
+    AVIOContext pb0, *pb = &pb0;
     int i;
     int64_t filesize = avio_size(s->pb);
 
-    pb = avio_alloc_context(buf, size, 0, NULL, NULL, NULL, NULL);
-    if (!pb)
-        return AVERROR(ENOMEM);
+    ffio_init_context(pb, buf, size, 0, NULL, NULL, NULL, NULL);
 
     ffio_read_varlen(pb); // track_index_len
     avio_r8(pb); // 'c'
@@ -448,7 +440,6 @@ static int track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *bu
     viv->sb_blocks = av_calloc(viv->n_sb_blocks, sizeof(VIV_SB_block));
     if (!viv->sb_blocks) {
         viv->n_sb_blocks = 0;
-        av_free(pb);
         return AVERROR(ENOMEM);
     }
 
@@ -479,11 +470,9 @@ static int track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *bu
         goto error;
 
     viv->sb_entries = av_calloc(maxnp, sizeof(VIV_SB_entry));
-    av_free(pb);
 
     return 0;
 error:
-    av_free(pb);
     viv->n_sb_blocks = 0;
     av_freep(&viv->sb_blocks);
     return AVERROR_INVALIDDATA;