[FFmpeg-devel] [PATCH] libavformat/vorbiscomment.c:fix warning:‘%03d’directive output may be truncated (PR #20433)

[caifan via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

PR #20433 opened by caifan
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20433
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20433.patch

libavformat/vorbiscomment.c:103:63: warning: ‘%03d’ directive output may be truncated writing between 3 and 10 bytes into a region of size 4 [-Wformat-truncation=]
snprintf(chapter_number, sizeof(chapter_number), "%03d", i);
      |                                           ^~~~
warning:‘%02d’ directive output may be truncated writing between 2 and 3 bytes into a region of size between 1 and 7 [-Wformat-truncation=]snprintf(chapter_time, sizeof(chapter_time), "%02d:%02d:%02d.%03d", h, m, s, ms);
      |                                                                     ^~~~
libavformat/vorbiscomment.c:104:58: note: directive argument in the range [-59, 59]
  104 |             snprintf(chapter_time, sizeof(chapter_time), "%02d:%02d:%02d.%03d", h, m, s, ms);
      |                                                          ^~~~~~~~~~~~~~~~~~~~~
libavformat/vorbiscomment.c:104:58: note: directive argument in the range [-999, 999]
In function ‘snprintf’,
    inlined from ‘ff_vorbiscomment_write’ at libavformat/vorbiscomment.c:104:13:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:71:10: note: ‘__builtin___snprintf_chk’ output between 13 and 21 bytes into a destination of size 13
   71 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   72 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   73 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~

Signed-off-by: caifan3 <caifan3@xiaomi.com>


From df9bf99804e9954879c8ea55bbcc0d5e17761268 Mon Sep 17 00:00:00 2001
From: caifan3 <caifan3@xiaomi.com>
Date: Thu, 4 Sep 2025 20:14:02 +0800
Subject: [PATCH] =?UTF-8?q?libavformat/vorbiscomment.c:fix=20warning:?=
 =?UTF-8?q?=E2=80=98%03d=E2=80=99directive=20output=20may=20be=20truncated?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

libavformat/vorbiscomment.c:103:63: warning: ‘%03d’ directive output may be truncated writing between 3 and 10 bytes into a region of size 4 [-Wformat-truncation=]
snprintf(chapter_number, sizeof(chapter_number), "%03d", i);
      |                                           ^~~~
warning:‘%02d’ directive output may be truncated writing between 2 and 3 bytes into a region of size between 1 and 7 [-Wformat-truncation=]snprintf(chapter_time, sizeof(chapter_time), "%02d:%02d:%02d.%03d", h, m, s, ms);
      |                                                                     ^~~~
libavformat/vorbiscomment.c:104:58: note: directive argument in the range [-59, 59]
  104 |             snprintf(chapter_time, sizeof(chapter_time), "%02d:%02d:%02d.%03d", h, m, s, ms);
      |                                                          ^~~~~~~~~~~~~~~~~~~~~
libavformat/vorbiscomment.c:104:58: note: directive argument in the range [-999, 999]
In function ‘snprintf’,
    inlined from ‘ff_vorbiscomment_write’ at libavformat/vorbiscomment.c:104:13:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:71:10: note: ‘__builtin___snprintf_chk’ output between 13 and 21 bytes into a destination of size 13
   71 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   72 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   73 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~

Signed-off-by: caifan3 <caifan3@xiaomi.com>
---
 libavformat/vorbiscomment.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/vorbiscomment.c b/libavformat/vorbiscomment.c
index abe12fd586..fb2ea7eba1 100644
--- a/libavformat/vorbiscomment.c
+++ b/libavformat/vorbiscomment.c
@@ -91,8 +91,8 @@ int ff_vorbiscomment_write(AVIOContext *pb, const AVDictionary *m,
         }
         for (int i = 0; i < nb_chapters; i++) {
             AVChapter *chp = chapters[i];
-            char chapter_time[13];
-            char chapter_number[4];
+            char chapter_time[22];
+            char chapter_number[11];
             int h, m, s, ms;
 
             s  = av_rescale(chp->start, chp->time_base.num, chp->time_base.den);
-- 
2.49.1

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