sgidec: return meaningful error codes

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

libavcodec/sgidec.c

@@ -41,7 +41,7 @@ typedef struct SgiState {
  * @param out_buf Points to one line after the output buffer.
  * @param out_end end of line in output buffer
  * @param pixelstride pixel stride of input buffer
- * @return size of output in bytes, -1 if buffer overflows
+ * @return size of output in bytes, else return error code.
  */
 static int expand_rle_row(SgiState *s, uint8_t *out_buf,
                           uint8_t *out_end, int pixelstride)
@@ -58,7 +58,8 @@ static int expand_rle_row(SgiState *s, uint8_t *out_buf,
         }
 
         /* Check for buffer overflow. */
-        if(out_buf + pixelstride * (count-1) >= out_end) return -1;
+        if (out_buf + pixelstride * (count - 1) >= out_end)
+            return AVERROR_INVALIDDATA;
 
         if (pixel & 0x80) {
             while (count--) {
@@ -81,7 +82,7 @@ static int expand_rle_row(SgiState *s, uint8_t *out_buf,
  * Read a run length encoded SGI image.
  * @param out_buf output buffer
  * @param s the current image state
- * @return 0 if no error, else return error number.
+ * @return 0 if no error, else return error code.
  */
 static int read_rle_sgi(uint8_t *out_buf, SgiState *s)
 {
@@ -115,7 +116,7 @@ static int read_rle_sgi(uint8_t *out_buf, SgiState *s)
  * Read an uncompressed SGI image.
  * @param out_buf output buffer
  * @param s the current image state
- * @return 0 if read success, otherwise return -1.
+ * @return 0 if read success, else return error code.
  */
 static int read_uncompressed_sgi(unsigned char* out_buf, SgiState *s)
 {
@@ -181,13 +182,13 @@ static int decode_frame(AVCodecContext *avctx,
 
     if (s->bytes_per_channel != 1 && (s->bytes_per_channel != 2 || rle)) {
         av_log(avctx, AV_LOG_ERROR, "wrong channel number\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
     /* Check for supported image dimensions. */
     if (dimension != 2 && dimension != 3) {
         av_log(avctx, AV_LOG_ERROR, "wrong dimension number\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
     if (s->depth == SGI_GRAYSCALE) {
@@ -198,11 +199,11 @@ static int decode_frame(AVCodecContext *avctx,
         avctx->pix_fmt = s->bytes_per_channel == 2 ? AV_PIX_FMT_RGBA64BE : AV_PIX_FMT_RGBA;
     } else {
         av_log(avctx, AV_LOG_ERROR, "wrong picture format\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
     if (av_image_check_size(s->width, s->height, 0, avctx))
-        return -1;
+        return AVERROR_INVALIDDATA;
     avcodec_set_dimensions(avctx, s->width, s->height);
 
     if ((ret = ff_get_buffer(avctx, p, 0)) < 0)