0,0 → 1,184 |
/* |
* 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(struct _reent *<[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]>) |
struct _reent *<[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 <_ansi.h> |
#include <reent.h> |
#include <stdio.h> |
#include <errno.h> |
#include <sys/lock.h> |
#ifdef __CYGWIN__ |
#include <fcntl.h> |
#endif |
#include "local.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 (ptr, file, oflags, 0666)) < 0) |
{ |
__sfp_lock_acquire (); |
fp->_flags = 0; /* release */ |
#ifndef __SINGLE_THREAD__ |
__lock_close_recursive (fp->_lock); |
#endif |
__sfp_lock_release (); |
return NULL; |
} |
|
_flockfile (fp); |
|
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_r (ptr, fp, 0, SEEK_END); |
|
#ifdef __SCLE |
if (__stextmode (fp->_file)) |
fp->_flags |= __SCLE; |
#endif |
|
_funlockfile (fp); |
return fp; |
} |
|
#ifndef _REENT_ONLY |
|
FILE * |
_DEFUN(fopen, (file, mode), |
_CONST char *file _AND |
_CONST char *mode) |
{ |
return _fopen_r (_REENT, file, mode); |
} |
|
#endif |