gcc/libio/stdio/vsnprintf.c

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/* Copyright (C) 1994, 1997 Free Software Foundation, Inc.
This file is part of the GNU IO Library.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this library; see the file COPYING. If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA.
As a special exception, if you link this library with files
compiled with a GNU compiler to produce an executable, this does
not cause the resulting executable to be covered by the GNU General
Public License. This exception does not however invalidate any
other reasons why the executable file might be covered by the GNU
General Public License. */
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#include "libioP.h"
#include "strfile.h"
typedef struct
{
_IO_strfile f;
/* This is used for the characters which do not fit in the buffer
provided by the user. */
char overflow_buf[64];
} _IO_strnfile;
static int _IO_strn_overflow __P ((_IO_FILE *fp, int c));
static int
_IO_strn_overflow (fp, c)
_IO_FILE *fp;
int c;
{
/* When we come to here this means the user supplied buffer is
filled. But since we must return the number of characters which
would have been written in total we must provide a buffer for
further use. We can do this by writing on and on in the overflow
buffer in the _IO_strnfile structure. */
_IO_strnfile *snf = (_IO_strnfile *) fp;
if (fp->_IO_buf_base != snf->overflow_buf)
{
/* Terminate the string. We know that there is room for at
least one more character since we initialized the stream with
a size to make this possible. */
*fp->_IO_write_ptr = '\0';
_IO_setb (fp, snf->overflow_buf,
snf->overflow_buf + sizeof (snf->overflow_buf), 0);
fp->_IO_write_base = snf->overflow_buf;
fp->_IO_read_base = snf->overflow_buf;
fp->_IO_read_ptr = snf->overflow_buf;
fp->_IO_read_end = snf->overflow_buf + sizeof (snf->overflow_buf);
}
fp->_IO_write_ptr = snf->overflow_buf;
fp->_IO_write_end = snf->overflow_buf;
/* Since we are not really interested in storing the characters
which do not fit in the buffer we simply ignore it. */
return c;
}
static struct _IO_jump_t _IO_strn_jumps =
{
JUMP_INIT_DUMMY,
JUMP_INIT(finish, _IO_str_finish),
JUMP_INIT(overflow, _IO_strn_overflow),
JUMP_INIT(underflow, _IO_str_underflow),
JUMP_INIT(uflow, _IO_default_uflow),
JUMP_INIT(pbackfail, _IO_str_pbackfail),
JUMP_INIT(xsputn, _IO_default_xsputn),
JUMP_INIT(xsgetn, _IO_default_xsgetn),
JUMP_INIT(seekoff, _IO_str_seekoff),
JUMP_INIT(seekpos, _IO_default_seekpos),
JUMP_INIT(setbuf, _IO_default_setbuf),
JUMP_INIT(sync, _IO_default_sync),
JUMP_INIT(doallocate, _IO_default_doallocate),
JUMP_INIT(read, _IO_default_read),
JUMP_INIT(write, _IO_default_write),
JUMP_INIT(seek, _IO_default_seek),
JUMP_INIT(close, _IO_default_close),
JUMP_INIT(stat, _IO_default_stat)
};
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int
_IO_vsnprintf (string, maxlen, format, args)
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char *string;
_IO_size_t maxlen;
const char *format;
_IO_va_list args;
{
_IO_strnfile sf;
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int ret;
#ifdef _IO_MTSAFE_IO
_IO_lock_t lock;
sf.f._sbf._f._lock = &lock;
#endif
/* We need to handle the special case where MAXLEN is 0. Use the
overflow buffer right from the start. */
if (maxlen == 0)
{
string = sf.overflow_buf;
maxlen = sizeof (sf.overflow_buf);
}
_IO_init ((_IO_FILE *) &sf, 0);
_IO_JUMPS ((_IO_FILE *) &sf) = &_IO_strn_jumps;
_IO_str_init_static ((_IO_FILE *) &sf, string, maxlen - 1, string);
ret = _IO_vfprintf ((_IO_FILE *) &sf, format, args);
if (sf.f._sbf._f._IO_buf_base != sf.overflow_buf)
*sf.f._sbf._f._IO_write_ptr = '\0';
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return ret;
}
#ifdef weak_alias
weak_alias (_IO_vsnprintf, __vsnprintf)
weak_alias (_IO_vsnprintf, vsnprintf)
#endif