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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [stdio/] [fopen.c] - Rev 232
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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(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
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