lavc/c93: use meaningful error codes

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/c93.c

@@ -83,7 +83,7 @@ static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
     if (from_y + height > HEIGHT) {
         av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
                offset);
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
     if (overflow > 0) {
@@ -127,16 +127,16 @@ static int decode_frame(AVCodecContext *avctx, void *data,
     AVFrame *picture = data;
     GetByteContext gb;
     uint8_t *out;
-    int stride, i, x, y, b, bt = 0;
+    int stride, ret, i, x, y, b, bt = 0;
 
     c93->currentpic ^= 1;
 
     newpic->reference = 3;
     newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
                          FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
-    if (avctx->reget_buffer(avctx, newpic)) {
+    if ((ret = avctx->reget_buffer(avctx, newpic))) {
         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
-        return -1;
+        return ret;
     }
 
     stride = newpic->linesize[0];
@@ -167,7 +167,7 @@ static int decode_frame(AVCodecContext *avctx, void *data,
             case C93_8X8_FROM_PREV:
                 offset = bytestream2_get_le16(&gb);
                 if (copy_block(avctx, out, copy_from, offset, 8, stride))
-                    return -1;
+                    return AVERROR_INVALIDDATA;
                 break;
 
             case C93_4X4_FROM_CURR:
@@ -178,7 +178,7 @@ static int decode_frame(AVCodecContext *avctx, void *data,
                         offset = bytestream2_get_le16(&gb);
                         if (copy_block(avctx, &out[j*stride+i],
                                            copy_from, offset, 4, stride))
-                            return -1;
+                            return AVERROR_INVALIDDATA;
                     }
                 }
                 break;
@@ -225,7 +225,7 @@ static int decode_frame(AVCodecContext *avctx, void *data,
             default:
                 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
                        block_type, x, y);
-                return -1;
+                return AVERROR_INVALIDDATA;
             }
             bt >>= 4;
             out += 8;