WebSVN - shark - Blame - Rev 1618 - /shark/branches/xen/libc/stdio/freopen.c

Rev	Author	Line No.	Line
2	pj	1	/*-
		2	* Copyright (c) 1990, 1993
		3	* The Regents of the University of California. All rights reserved.
		4	*
		5	* This code is derived from software contributed to Berkeley by
		6	* Chris Torek.
		7	*
		8	* Redistribution and use in source and binary forms, with or without
		9	* modification, are permitted provided that the following conditions
		10	* are met:
		11	* 1. Redistributions of source code must retain the above copyright
		12	* notice, this list of conditions and the following disclaimer.
		13	* 2. Redistributions in binary form must reproduce the above copyright
		14	* notice, this list of conditions and the following disclaimer in the
		15	* documentation and/or other materials provided with the distribution.
		16	* 3. All advertising materials mentioning features or use of this software
		17	* must display the following acknowledgement:
		18	* This product includes software developed by the University of
		19	* California, Berkeley and its contributors.
		20	* 4. Neither the name of the University nor the names of its contributors
		21	* may be used to endorse or promote products derived from this software
		22	* without specific prior written permission.
		23	*
		24	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
		25	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
		26	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
		27	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
		28	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
		29	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
		30	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
		31	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
		32	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
		33	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
		34	* SUCH DAMAGE.
		35	*/
		36
		37	#if defined(LIBC_SCCS) && !defined(lint)
		38	static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93";
		39	#endif /* LIBC_SCCS and not lint */
		40
		41	#include <sys/types.h>
		42	#include <sys/stat.h>
		43	#include <fcntl.h>
		44	#include <errno.h>
		45	#include <unistd.h>
		46	#include <stdio.h>
		47	#include <stdlib.h>
		48	#include "local.h"
		49
		50	/*
		51	* Re-direct an existing, open (probably) file to some other file.
		52	* ANSI is written such that the original file gets closed if at
		53	* all possible, no matter what.
		54	*/
		55	FILE *
		56	freopen(file, mode, fp)
		57	const char file, mode;
		58	register FILE *fp;
		59	{
		60	register int f;
		61	int flags, isopen, oflags, sverrno, wantfd;
		62
		63	if ((flags = __sflags(mode, &oflags)) == 0) {
		64	(void) fclose(fp);
		65	return (NULL);
		66	}
		67
		68	if (!__sdidinit)
		69	__sinit();
		70
		71	/*
		72	* There are actually programs that depend on being able to "freopen"
		73	* descriptors that weren't originally open. Keep this from breaking.
		74	* Remember whether the stream was open to begin with, and which file
		75	* descriptor (if any) was associated with it. If it was attached to
		76	* a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
		77	* should work. This is unnecessary if it was not a Unix file.
		78	*/
		79	if (fp->_flags == 0) {
		80	fp->_flags = __SEOF; /* hold on to it */
		81	isopen = 0;
		82	wantfd = -1;
		83	} else {
		84	/* flush the stream; ANSI doesn't require this. */
		85	if (fp->_flags & __SWR)
		86	(void) __sflush(fp);
		87	/* if close is NULL, closing is a no-op, hence pointless */
		88	isopen = fp->_close != NULL;
		89	if ((wantfd = fp->_file) < 0 && isopen) {
		90	(void) (*fp->_close)(fp->_cookie);
		91	isopen = 0;
		92	}
		93	}
		94
		95	/* Get a new descriptor to refer to the new file. */
		96	f = open(file, oflags, DEFFILEMODE);
		97	if (f < 0 && isopen) {
		98	/* If out of fd's close the old one and try again. */
		99	if (errno == ENFILE \|\| errno == EMFILE) {
		100	(void) (*fp->_close)(fp->_cookie);
		101	isopen = 0;
		102	f = open(file, oflags, DEFFILEMODE);
		103	}
		104	}
		105	sverrno = errno;
		106
		107	/*
		108	* Finish closing fp. Even if the open succeeded above, we cannot
		109	* keep fp->_base: it may be the wrong size. This loses the effect
		110	* of any setbuffer calls, but stdio has always done this before.
		111	*/
		112	if (isopen)
		113	(void) (*fp->_close)(fp->_cookie);
		114	if (fp->_flags & __SMBF)
		115	free((char *)fp->_bf._base);
		116	fp->_w = 0;
		117	fp->_r = 0;
		118	fp->_p = NULL;
		119	fp->_bf._base = NULL;
		120	fp->_bf._size = 0;
		121	fp->_lbfsize = 0;
		122	if (HASUB(fp))
		123	FREEUB(fp);
		124	fp->_ub._size = 0;
		125	if (HASLB(fp))
		126	FREELB(fp);
		127	fp->_lb._size = 0;
		128
		129	if (f < 0) { /* did not get it after all */
		130	fp->_flags = 0; /* set it free */
		131	errno = sverrno; /* restore in case _close clobbered */
		132	return (NULL);
		133	}
		134
		135	/*
		136	* If reopening something that was open before on a real file, try
		137	* to maintain the descriptor. Various C library routines (perror)
		138	* assume stderr is always fd STDERR_FILENO, even if being freopen'd.
		139	*/
		140	if (wantfd >= 0 && f != wantfd) {
		141	if (dup2(f, wantfd) >= 0) {
		142	(void) close(f);
		143	f = wantfd;
		144	}
		145	}
		146
		147	fp->_flags = flags;
		148	fp->_file = f;
		149	fp->_cookie = fp;
		150	fp->_read = __sread;
		151	fp->_write = __swrite;
		152	fp->_seek = __sseek;
		153	fp->_close = __sclose;
		154	return (fp);
		155	}

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