NetBSD/lib/libpthread/stdio/freopen.c

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1994-02-08 01:05:21 +03:00
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
/*static char *sccsid = "from: @(#)freopen.c 5.6 (Berkeley) 2/24/91";*/
static char *rcsid = "$Id: freopen.c,v 1.1 1994/02/07 22:05:56 proven Exp $";
#endif /* LIBC_SCCS and not lint */
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include "local.h"
extern pthread_mutex_t __sfp_mutex;
extern pthread_cond_t __sfp_cond;
extern int __sfp_state;
/*
* Re-direct an existing, open (probably) file to some other file.
* ANSI is written such that the original file gets closed if at
* all possible, no matter what.
*/
FILE *
freopen(file, mode, fp)
const char *file, *mode;
register FILE *fp;
{
int f, flags, oflags;
FILE *ret;
if ((flags = __sflags(mode, &oflags)) == 0) {
(void) fclose(fp);
return (NULL);
}
pthread_once(&__sdidinit, __sinit);
/*
* There are actually programs that depend on being able to "freopen"
* descriptors that weren't originally open. Keep this from breaking.
* Remember whether the stream was open to begin with, and which file
* descriptor (if any) was associated with it. If it was attached to
* a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
* should work. This is unnecessary if it was not a Unix file.
*/
/* while lock __sfp_mutex, to block out fopen, and other freopen calls */
while (pthread_mutex_lock(&__sfp_mutex) == OK) {
if (ftrylockfile(fp) == OK) {
if (fp->_flags) {
/* flush the stream; ANSI doesn't require this. */
if (fp->_flags & __SWR)
(void) __sflush(fp);
__sclose(fp);
/*
* Finish closing fp. We cannot keep fp->_base:
* it may be the wrong size. This loses the effect
* of any setbuffer calls, but stdio has always done
* this before.
* NOTE: We do this even if __ftrylockfilr failed with
* an error to avoid memory leaks.
*/
if (fp->_flags & __SMBF)
free((char *)fp->_bf._base);
fp->_w = 0;
fp->_r = 0;
fp->_p = NULL;
fp->_bf._base = NULL;
fp->_bf._size = 0;
fp->_lbfsize = 0;
if (HASUB(fp))
FREEUB(fp);
fp->_ub._size = 0;
if (HASLB(fp))
FREELB(fp);
fp->_lb._size = 0;
}
/* Get a new descriptor to refer to the new file. */
if ((f = open(file, oflags, 0666)) < OK)
ret = NULL;
/*
* If reopening something that was open before on a real file, try
* to maintain the descriptor. Various C library routines (perror)
* assume stderr is always fd STDERR_FILENO, even if being freopen'd.
*/
/* Testing f == fp->_file may no longer be necessary */
if (fp->_file >= 0 && f != fp->_file) {
if (dup2(f, fp->_file) >= OK) {
(void)close(f);
f = fp->_file;
}
}
fp->_flags = flags;
fp->_file = f;
ret = fp;
break;
} else {
/* unlock __sfp_mutex, and try again later */
pthread_mutex_unlock(&__sfp_mutex);
pthread_yield();
continue;
}
pthread_mutex_unlock(&__sfp_mutex);
funlockfile(fp);
return(ret);
}
(void)fclose(fp);
return(NULL);
}