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FFmpeg/compat/msvcrt/snprintf.c

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/*
* C99-compatible snprintf() and vsnprintf() implementations
* Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include <stdarg.h>
#include <limits.h>
#include <string.h>
#include "compat/va_copy.h"
#include "libavutil/error.h"
#if defined(__MINGW32__)
#define EOVERFLOW EFBIG
#endif
int avpriv_snprintf(char *s, size_t n, const char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = avpriv_vsnprintf(s, n, fmt, ap);
va_end(ap);
return ret;
}
int avpriv_vsnprintf(char *s, size_t n, const char *fmt,
va_list ap)
{
int ret;
va_list ap_copy;
if (n == 0)
return _vscprintf(fmt, ap);
else if (n > INT_MAX)
return AVERROR(EOVERFLOW);
/* we use n - 1 here because if the buffer is not big enough, the MS
* runtime libraries don't add a terminating zero at the end. MSDN
* recommends to provide _snprintf/_vsnprintf() a buffer size that
* is one less than the actual buffer, and zero it before calling
* _snprintf/_vsnprintf() to workaround this problem.
* See https://web.archive.org/web/20151214111935/http://msdn.microsoft.com/en-us/library/1kt27hek(v=vs.80).aspx */
memset(s, 0, n);
va_copy(ap_copy, ap);
ret = _vsnprintf(s, n - 1, fmt, ap_copy);
va_end(ap_copy);
if (ret == -1)
ret = _vscprintf(fmt, ap);
return ret;
}