156 lines
4.9 KiB
C
156 lines
4.9 KiB
C
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "local.h"
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/*
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* Re-direct an existing, open (probably) file to some other file.
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* ANSI is written such that the original file gets closed if at
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* all possible, no matter what.
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*/
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FILE *
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freopen(file, mode, fp)
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const char *file, *mode;
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register FILE *fp;
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{
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register int f;
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int flags, isopen, oflags, sverrno, wantfd;
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if ((flags = __sflags(mode, &oflags)) == 0) {
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(void) fclose(fp);
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return (NULL);
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}
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if (!__sdidinit)
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__sinit();
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/*
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* There are actually programs that depend on being able to "freopen"
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* descriptors that weren't originally open. Keep this from breaking.
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* Remember whether the stream was open to begin with, and which file
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* descriptor (if any) was associated with it. If it was attached to
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* a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
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* should work. This is unnecessary if it was not a Unix file.
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*/
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if (fp->_flags == 0) {
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fp->_flags = __SEOF; /* hold on to it */
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isopen = 0;
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wantfd = -1;
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} else {
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/* flush the stream; ANSI doesn't require this. */
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if (fp->_flags & __SWR)
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(void) __sflush(fp);
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/* if close is NULL, closing is a no-op, hence pointless */
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isopen = fp->_close != NULL;
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if ((wantfd = fp->_file) < 0 && isopen) {
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(void) (*fp->_close)(fp->_cookie);
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isopen = 0;
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}
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}
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/* Get a new descriptor to refer to the new file. */
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f = open(file, oflags, DEFFILEMODE);
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if (f < 0 && isopen) {
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/* If out of fd's close the old one and try again. */
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if (errno == ENFILE || errno == EMFILE) {
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(void) (*fp->_close)(fp->_cookie);
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isopen = 0;
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f = open(file, oflags, DEFFILEMODE);
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}
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}
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sverrno = errno;
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/*
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* Finish closing fp. Even if the open succeeded above, we cannot
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* keep fp->_base: it may be the wrong size. This loses the effect
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* of any setbuffer calls, but stdio has always done this before.
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*/
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if (isopen)
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(void) (*fp->_close)(fp->_cookie);
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if (fp->_flags & __SMBF)
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free((char *)fp->_bf._base);
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fp->_w = 0;
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fp->_r = 0;
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fp->_p = NULL;
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fp->_bf._base = NULL;
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fp->_bf._size = 0;
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fp->_lbfsize = 0;
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if (HASUB(fp))
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FREEUB(fp);
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fp->_ub._size = 0;
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if (HASLB(fp))
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FREELB(fp);
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fp->_lb._size = 0;
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if (f < 0) { /* did not get it after all */
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fp->_flags = 0; /* set it free */
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errno = sverrno; /* restore in case _close clobbered */
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return (NULL);
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}
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/*
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* If reopening something that was open before on a real file, try
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* to maintain the descriptor. Various C library routines (perror)
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* assume stderr is always fd STDERR_FILENO, even if being freopen'd.
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*/
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if (wantfd >= 0 && f != wantfd) {
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if (dup2(f, wantfd) >= 0) {
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(void) close(f);
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f = wantfd;
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}
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}
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fp->_flags = flags;
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fp->_file = f;
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fp->_cookie = fp;
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fp->_read = __sread;
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fp->_write = __swrite;
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fp->_seek = __sseek;
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fp->_close = __sclose;
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return (fp);
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}
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