glibc/stdio/fopen.c

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/* Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc.
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 <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define badmode() return ((errno = EINVAL), 0)
/* Dissect the given mode string into an __io_mode. */
int
DEFUN(__getmode, (mode, mptr), CONST char *mode AND __io_mode *mptr)
{
register unsigned char i;
if (mode == NULL)
badmode ();
memset ((PTR) mptr, 0, sizeof (*mptr));
switch (*mode)
{
case 'a':
mptr->__write = mptr->__create = mptr->__append = 1;
break;
case 'w':
mptr->__write = mptr->__create = mptr->__truncate = 1;
break;
case 'r':
mptr->__read = 1;
break;
default:
badmode ();
}
for (i = 1; i < 3; ++i)
{
++mode;
if (*mode == '\0')
break;
switch (*mode)
{
case '+':
mptr->__read = mptr->__write = 1;
break;
case 'b':
mptr->__binary = 1;
break;
}
}
if (!mptr->__read && !mptr->__write)
badmode ();
mptr->__exclusive = *mode == 'x';
return 1;
}
/* Open a new stream on the given file. */
FILE *
DEFUN(fopen, (filename, mode), CONST char *filename AND CONST char *mode)
{
FILE *stream;
__io_mode m;
if (filename == NULL)
{
errno = EINVAL;
return NULL;
}
if (!__getmode (mode, &m))
return NULL;
stream = __newstream ();
if (stream == NULL)
return NULL;
if (__stdio_open (filename, m, &stream->__cookie))
{
int save = errno;
(void) fclose (stream);
errno = save;
return NULL;
}
stream->__mode = m;
return stream;
}