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/*-
* Copyright (c) 1990, 1993
* 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. 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[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include "un-namespace.h"
#include "libc_private.h"
#include "local.h"
/*
* 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(const char * __restrict file, const char * __restrict mode,
FILE * __restrict fp)
{
int f;
int dflags, flags, isopen, oflags, sverrno, wantfd;
if ((flags = __sflags(mode, &oflags)) == 0) {
sverrno = errno;
(void) fclose(fp);
errno = sverrno;
return (NULL);
}
FLOCKFILE(fp);
if (!__sdidinit)
__sinit();
/*
* If the filename is a NULL pointer, the caller is asking us to
* re-open the same file with a different mode. We allow this only
* if the modes are compatible.
*/
if (file == NULL) {
/* See comment below regarding freopen() of closed files. */
if (fp->_flags == 0) {
FUNLOCKFILE(fp);
errno = EINVAL;
return (NULL);
}
if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) {
sverrno = errno;
fclose(fp);
FUNLOCKFILE(fp);
errno = sverrno;
return (NULL);
}
/* Work around incorrect O_ACCMODE. */
if ((dflags & O_ACCMODE) != O_RDWR &&
(dflags & (O_ACCMODE | O_EXEC)) != (oflags & O_ACCMODE)) {
fclose(fp);
FUNLOCKFILE(fp);
errno = EBADF;
return (NULL);
}
if (fp->_flags & __SWR)
(void) __sflush(fp);
if ((oflags ^ dflags) & O_APPEND) {
dflags &= ~O_APPEND;
dflags |= oflags & O_APPEND;
if (_fcntl(fp->_file, F_SETFL, dflags) < 0) {
sverrno = errno;
fclose(fp);
FUNLOCKFILE(fp);
errno = sverrno;
return (NULL);
}
}
if (oflags & O_TRUNC)
(void) ftruncate(fp->_file, (off_t)0);
if (!(oflags & O_APPEND))
(void) _sseek(fp, (fpos_t)0, SEEK_SET);
if (oflags & O_CLOEXEC)
(void) _fcntl(fp->_file, F_SETFD, FD_CLOEXEC);
f = fp->_file;
isopen = 0;
wantfd = -1;
goto finish;
}
/*
* 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.
*/
if (fp->_flags == 0) {
fp->_flags = __SEOF; /* hold on to it */
isopen = 0;
wantfd = -1;
} else {
/* flush the stream; ANSI doesn't require this. */
if (fp->_flags & __SWR)
(void) __sflush(fp);
/* if close is NULL, closing is a no-op, hence pointless */
isopen = fp->_close != NULL;
if ((wantfd = fp->_file) < 0 && isopen) {
(void) (*fp->_close)(fp->_cookie);
isopen = 0;
}
}
/* Get a new descriptor to refer to the new file. */
f = _open(file, oflags, DEFFILEMODE);
/* If out of fd's close the old one and try again. */
if (f < 0 && isopen && wantfd > STDERR_FILENO &&
(errno == ENFILE || errno == EMFILE)) {
(void) (*fp->_close)(fp->_cookie);
isopen = 0;
wantfd = -1;
f = _open(file, oflags, DEFFILEMODE);
}
sverrno = errno;
finish:
/*
* Finish closing fp. Even if the open succeeded above, 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.
*
* Leave the existing file descriptor open until dup2() is called
* below to avoid races where a concurrent open() in another thread
* could claim the existing descriptor.
*/
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;
fp->_orientation = 0;
memset(&fp->_mbstate, 0, sizeof(mbstate_t));
if (f < 0) { /* did not get it after all */
if (isopen)
(void) (*fp->_close)(fp->_cookie);
fp->_flags = 0; /* set it free */
FUNLOCKFILE(fp);
errno = sverrno; /* restore in case _close clobbered */
return (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.
*/
if (wantfd >= 0) {
if ((oflags & O_CLOEXEC ? _fcntl(f, F_DUP2FD_CLOEXEC, wantfd) :
_dup2(f, wantfd)) >= 0) {
(void)_close(f);
f = wantfd;
} else
(void)_close(fp->_file);
}
/*
* File descriptors are a full int, but _file is only a short.
* If we get a valid file descriptor that is greater than
* SHRT_MAX, then the fd will get sign-extended into an
* invalid file descriptor. Handle this case by failing the
* open.
*/
if (f > SHRT_MAX) {
fp->_flags = 0; /* set it free */
FUNLOCKFILE(fp);
errno = EMFILE;
return (NULL);
}
fp->_flags = flags;
fp->_file = f;
fp->_cookie = fp;
fp->_read = __sread;
fp->_write = __swrite;
fp->_seek = __sseek;
fp->_close = __sclose;
/*
* When opening in append mode, even though we use O_APPEND,
* we need to seek to the end so that ftell() gets the right
* answer. If the user then alters the seek pointer, or
* the file extends, this will fail, but there is not much
* we can do about this. (We could set __SAPP and check in
* fseek and ftell.)
*/
if (oflags & O_APPEND)
(void) _sseek(fp, (fpos_t)0, SEEK_END);
FUNLOCKFILE(fp);
return (fp);
}
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