[FFmpeg-devel] [RFC]lavu/timecode: Increase AV_TIMECODE_STR_SIZE.

[Carl Eugen Hoyos]

Hi!

Attached patch is one possibility to fix the following warning with gcc 7:
libavutil/timecode.c: In function ‘av_timecode_make_string’:
libavutil/timecode.c:103:60: warning: ‘%02d’ directive output may be truncated 
writing between 2 and 10 bytes into a region of size between 0 and 7 
[-Wformat-truncation=]
     snprintf(buf, AV_TIMECODE_STR_SIZE, "%s%02d:%02d:%02d%c%02d",
                                                            ^~~~
libavutil/timecode.c:103:41: note: directive argument in the range [0, 
2147483647]
     snprintf(buf, AV_TIMECODE_STR_SIZE, "%s%02d:%02d:%02d%c%02d",
                                         ^~~~~~~~~~~~~~~~~~~~~~~~
libavutil/timecode.c:103:5: note: ‘snprintf’ output between 12 and 32 bytes 
into a destination of size 16
     snprintf(buf, AV_TIMECODE_STR_SIZE, "%s%02d:%02d:%02d%c%02d",
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
              neg ? "-" : "",
              ~~~~~~~~~~~~~~~
              hh, mm, ss, drop ? ';' : ':', ff);
              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Several similar warnings are printed, an alternative is to disable the 
warning.

The warning seemed wrong on first sight but may actually be correct, we 
accept invalid fps for timecode.

Carl Eugen
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From 8906d9b41b5576ddc0bc5f79f1192001825b89c7 Mon Sep 17 00:00:00 2001
From: Carl Eugen Hoyos <cehoyos at ag.or.at>
Date: Fri, 5 May 2017 01:23:24 +0200
Subject: [PATCH] lavu/timecode: Increase AV_TIMECODE_STR_SIZE.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fixes the following warning:
libavutil/timecode.c:103:60: warning: ���%02d��� directive output may be truncated writing between 2 and 10 bytes into a region of size between 0 and 7
---
 libavutil/timecode.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavutil/timecode.h b/libavutil/timecode.h
index 56e3975..37c1361 100644
--- a/libavutil/timecode.h
+++ b/libavutil/timecode.h
@@ -30,7 +30,7 @@
 #include <stdint.h>
 #include "rational.h"
 
-#define AV_TIMECODE_STR_SIZE 16
+#define AV_TIMECODE_STR_SIZE 23
 
 enum AVTimecodeFlag {
     AV_TIMECODE_FLAG_DROPFRAME      = 1<<0, ///< timecode is drop frame
-- 
1.7.10.4