avcodec/flac_parser: Remove superfluous checks

For a parser, the input buffer is always != NULL: In case of flushing,
the indicated size of the input buffer will be zero and the input buffer
will point to a zeroed buffer of size 0 + AV_INPUT_BUFFER_PADDING.
Therefore one does not need to check for whether said buffer is NULL or
not.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/flac_parser.c

@@ -584,17 +584,16 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
     }
 
     /* Find and score new headers.                                     */
-    /* buf_size is to zero when padding, so check for this since we do */
+    /* buf_size is zero when flushing, so check for this since we do   */
     /* not want to try to read more input once we have found the end.  */
-    /* Note that as (non-modified) parameters, buf can be non-NULL,    */
-    /* while buf_size is 0.                                            */
-    while ((buf && buf_size && read_end < buf + buf_size &&
+    /* Also note that buf can't be NULL.                               */
+    while ((buf_size && read_end < buf + buf_size &&
             fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
-           || ((!buf || !buf_size) && !fpc->end_padded)) {
+           || (!buf_size && !fpc->end_padded)) {
         int start_offset;
 
         /* Pad the end once if EOF, to check the final region for headers. */
-        if (!buf || !buf_size) {
+        if (!buf_size) {
             fpc->end_padded      = 1;
             buf_size = MAX_FRAME_HEADER_SIZE;
             read_end = read_start + MAX_FRAME_HEADER_SIZE;
@@ -624,7 +623,7 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
             goto handle_error;
         }
 
-        if (buf && buf_size) {
+        if (buf_size) {
             av_fifo_generic_write(fpc->fifo_buf, (void*) read_start,
                                   read_end - read_start, NULL);
         } else {
@@ -647,7 +646,7 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
         fpc->nb_headers_buffered = nb_headers;
         /* Wait till FLAC_MIN_HEADERS to output a valid frame. */
         if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) {
-            if (buf && read_end < buf + buf_size) {
+            if (read_end < buf + buf_size) {
                 read_start = read_end;
                 continue;
             } else {
@@ -682,7 +681,7 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
 
     if (fpc->best_header && fpc->best_header->max_score <= 0) {
         // Only accept a bad header if there is no other option to continue
-        if (!buf_size || !buf || read_end != buf || fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
+        if (!buf_size || read_end != buf || fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
             fpc->best_header = NULL;
     }