| /* |
| * 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 |