FFmpeg
snprintf.c
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1 /*
2  * C99-compatible snprintf() and vsnprintf() implementations
3  * Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include <stdio.h>
23 #include <stdarg.h>
24 #include <limits.h>
25 #include <string.h>
26 
27 #include "compat/va_copy.h"
28 #include "libavutil/error.h"
29 
30 #if defined(__MINGW32__)
31 #define EOVERFLOW EFBIG
32 #endif
33 
34 int avpriv_snprintf(char *s, size_t n, const char *fmt, ...)
35 {
36  va_list ap;
37  int ret;
38 
39  va_start(ap, fmt);
40  ret = avpriv_vsnprintf(s, n, fmt, ap);
41  va_end(ap);
42 
43  return ret;
44 }
45 
46 int avpriv_vsnprintf(char *s, size_t n, const char *fmt,
47  va_list ap)
48 {
49  int ret;
50  va_list ap_copy;
51 
52  if (n == 0)
53  return _vscprintf(fmt, ap);
54  else if (n > INT_MAX)
55  return AVERROR(EOVERFLOW);
56 
57  /* we use n - 1 here because if the buffer is not big enough, the MS
58  * runtime libraries don't add a terminating zero at the end. MSDN
59  * recommends to provide _snprintf/_vsnprintf() a buffer size that
60  * is one less than the actual buffer, and zero it before calling
61  * _snprintf/_vsnprintf() to workaround this problem.
62  * See http://msdn.microsoft.com/en-us/library/1kt27hek(v=vs.80).aspx */
63  memset(s, 0, n);
64  va_copy(ap_copy, ap);
65  ret = _vsnprintf(s, n - 1, fmt, ap_copy);
66  va_end(ap_copy);
67  if (ret == -1)
68  ret = _vscprintf(fmt, ap);
69 
70  return ret;
71 }
const char * fmt
Definition: avisynth_c.h:861
#define va_copy(dst, src)
Definition: va_copy.h:31
int avpriv_snprintf(char *s, size_t n, const char *fmt,...)
Definition: snprintf.c:34
error code definitions
#define s(width, name)
Definition: cbs_vp9.c:257
int n
Definition: avisynth_c.h:760
int avpriv_vsnprintf(char *s, size_t n, const char *fmt, va_list ap)
Definition: snprintf.c:46
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions