[FFmpeg-cvslog] avformat/hlsenc: Only write something if there is something to write

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Tue Nov  9 22:21:37 2021 +0100| [96fe44e2e8e4c77e66cbb0834d340719741e964c] | committer: Andreas Rheinhardt

avformat/hlsenc: Only write something if there is something to write

This is especially important in case avio_write() would be switched
to an unsigned type like size_t, then a potential error from avio_read()
(with negative return value) would no longer be handled gracefully by
avio_write().

Reviewed-by: Steven Liu <lq at chinaffmpeg.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=96fe44e2e8e4c77e66cbb0834d340719741e964c
---

 libavformat/hlsenc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
index 557cf1bee3..cfd0c036d1 100644
--- a/libavformat/hlsenc.c
+++ b/libavformat/hlsenc.c
@@ -2383,8 +2383,8 @@ static int64_t append_single_file(AVFormatContext *s, VariantStream *vs)
 
     do {
         read_byte = avio_read(vs->out, buf, BUFSIZE);
-        avio_write(vs->out_single_file, buf, read_byte);
         if (read_byte > 0) {
+            avio_write(vs->out_single_file, buf, read_byte);
             total_size += read_byte;
             ret = total_size;
         }