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/*
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
/*
FUNCTION
<<fopen>>---open a file
INDEX
fopen
INDEX
_fopen_r
ANSI_SYNOPSIS
#include <stdio.h>
FILE *fopen(const char *<[file]>, const char *<[mode]>);
FILE *_fopen_r(void *<[reent]>,
const char *<[file]>, const char *<[mode]>);
TRAD_SYNOPSIS
#include <stdio.h>
FILE *fopen(<[file]>, <[mode]>)
char *<[file]>;
char *<[mode]>;
FILE *_fopen_r(<[reent]>, <[file]>, <[mode]>)
char *<[reent]>;
char *<[file]>;
char *<[mode]>;
DESCRIPTION
<<fopen>> initializes the data structures needed to read or write a
file. Specify the file's name as the string at <[file]>, and the kind
of access you need to the file with the string at <[mode]>.
The alternate function <<_fopen_r>> is a reentrant version.
The extra argument <[reent]> is a pointer to a reentrancy structure.
Three fundamental kinds of access are available: read, write, and append.
<<*<[mode]>>> must begin with one of the three characters `<<r>>',
`<<w>>', or `<<a>>', to select one of these:
o+
o r
Open the file for reading; the operation will fail if the file does
not exist, or if the host system does not permit you to read it.
o w
Open the file for writing @emph{from the beginning} of the file:
effectively, this always creates a new file. If the file whose name you
specified already existed, its old contents are discarded.
o a
Open the file for appending data, that is writing from the end of
file. When you open a file this way, all data always goes to the
current end of file; you cannot change this using <<fseek>>.
o-
Some host systems distinguish between ``binary'' and ``text'' files.
Such systems may perform data transformations on data written to, or
read from, files opened as ``text''.
If your system is one of these, then you can append a `<<b>>' to any
of the three modes above, to specify that you are opening the file as
a binary file (the default is to open the file as a text file).
`<<rb>>', then, means ``read binary''; `<<wb>>', ``write binary''; and
`<<ab>>', ``append binary''.
To make C programs more portable, the `<<b>>' is accepted on all
systems, whether or not it makes a difference.
Finally, you might need to both read and write from the same file.
You can also append a `<<+>>' to any of the three modes, to permit
this. (If you want to append both `<<b>>' and `<<+>>', you can do it
in either order: for example, <<"rb+">> means the same thing as
<<"r+b">> when used as a mode string.)
Use <<"r+">> (or <<"rb+">>) to permit reading and writing anywhere in
an existing file, without discarding any data; <<"w+">> (or <<"wb+">>)
to create a new file (or begin by discarding all data from an old one)
that permits reading and writing anywhere in it; and <<"a+">> (or
<<"ab+">>) to permit reading anywhere in an existing file, but writing
only at the end.
RETURNS
<<fopen>> returns a file pointer which you can use for other file
operations, unless the file you requested could not be opened; in that
situation, the result is <<NULL>>. If the reason for failure was an
invalid string at <[mode]>, <<errno>> is set to <<EINVAL>>.
PORTABILITY
<<fopen>> is required by ANSI C.
Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
<<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "%W% (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */
#include <stdio.h>
#include <errno.h>
#include "local.h"
#ifdef __CYGWIN__
#include <fcntl.h>
#endif
#include <sys/lock.h>
FILE *
_DEFUN (_fopen_r, (ptr, file, mode),
struct _reent *ptr _AND
_CONST char *file _AND
_CONST char *mode)
{
register FILE *fp;
register int f;
int flags, oflags;
if ((flags = __sflags (ptr, mode, &oflags)) == 0)
return NULL;
if ((fp = __sfp (ptr)) == NULL)
return NULL;
if ((f = _open_r (fp->_data, file, oflags, 0666)) < 0)
{
fp->_flags = 0; /* release */
return NULL;
}
fp->_file = f;
fp->_flags = flags;
fp->_cookie = (_PTR) fp;
fp->_read = __sread;
fp->_write = __swrite;
fp->_seek = __sseek;
fp->_close = __sclose;
if (fp->_flags & __SAPP)
fseek (fp, 0, SEEK_END);
#ifdef __SCLE
if (__stextmode (fp->_file))
fp->_flags |= __SCLE;
#endif
#ifndef __SINGLE_THREAD__
__lock_init_recursive (*(_LOCK_RECURSIVE_T *)&fp->_lock);
#endif
return fp;
}
#ifndef _REENT_ONLY
FILE *
_DEFUN (fopen, (file, mode),
_CONST char *file _AND
_CONST char *mode)
{
return _fopen_r (_REENT, file, mode);
}
#endif
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