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FFmpeg/compat/msvcrt/snprintf.c
Ronald S. Bultje c1c8fdab46 compat/vsnprintf: return number of bytes required on truncation.
This conforms to C99, but requires Windows >= XP.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
2012-09-15 14:33:11 -04:00

71 lines
2.1 KiB
C

/*
* C99-compatible snprintf() and vsnprintf() implementations
* Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; 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 "libavutil/error.h"
#if !defined(va_copy) && defined(_MSC_VER)
#define va_copy(dst, src) ((dst) = (src))
#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 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;
}