glibc/stdio/vsnprintf.c

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/* Copyright (C) 1991, 1992, 1995 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
/*
* Write formatted output to S according to the format string
* FORMAT, using the argument list in ARG, writing no more
* than MAXLEN characters.
*/
int
__vsnprintf (char *s, size_t maxlen, const char *format, va_list arg)
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{
int done;
FILE f;
memset((PTR) &f, 0, sizeof(f));
f.__magic = _IOMAGIC;
f.__mode.__write = 1;
/* The buffer size is one less than MAXLEN
so we have space for the null terminator. */
f.__bufp = f.__buffer = (char *) s;
f.__bufsize = maxlen - 1;
f.__put_limit = f.__buffer + f.__bufsize;
f.__get_limit = f.__buffer;
/* After the buffer is full (MAXLEN characters have been written),
any more characters written will go to the bit bucket. */
f.__room_funcs = __default_room_functions;
f.__io_funcs.__write = NULL;
f.__seen = 1;
done = vfprintf(&f, format, arg);
*f.__bufp = '\0';
return done;
}
weak_alias (__vsnprintf, vsnprintf)