[apple/libc.git] / stdio / FreeBSD / freopen.c

/*-
 * 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.
 * 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[] = "@(#)freopen.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/stdio/freopen.c,v 1.21 2008/04/17 22:17:54 jhb Exp $");

#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(file, mode, fp)
	const char * __restrict file;
	const char * __restrict mode;
	FILE *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);
	}

	pthread_once(&__sdidinit, __sinit);
	
	FLOCKFILE(fp);

	/*
	 * 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);
		}
		if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) !=
		    (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);
		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.
	 *
	 * For UNIX03, we always close if it was open.
	 */
	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 */
#if __DARWIN_UNIX03
		if (fp->_close)
			(void) (*fp->_close)(fp->_cookie);
		isopen = 0;
		wantfd = -1;
#else /* !__DARWIN_UNIX03 */
		isopen = fp->_close != NULL;
		if ((wantfd = fp->_file) < 0 && isopen) {
			(void) (*fp->_close)(fp->_cookie);
			isopen = 0;
		}
#endif /* __DARWIN_UNIX03 */
	}

	/* Get a new descriptor to refer to the new file. */
	f = _open(file, oflags, DEFFILEMODE);
	if (f < 0 && isopen) {
		/* If out of fd's close the old one and try again. */
		if (errno == ENFILE || errno == EMFILE) {
			(void) (*fp->_close)(fp->_cookie);
			isopen = 0;
			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.
	 */
	if (isopen)
		(void) (*fp->_close)(fp->_cookie);
	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 */
		FUNLOCKFILE(fp);
		__sfprelease(fp);	/* set it free */
		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 && f != wantfd) {
		if (_dup2(f, wantfd) >= 0) {
			(void)_close(f);
			f = wantfd;
		}
	}

	/*
	 * 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) {
		FUNLOCKFILE(fp);
		__sfprelease(fp);	/* set it free */
		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);
}
Commit	Line	Data
9385eb3d	1	/*-
e9ce8d39 A	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.
e9ce8d39 A	16	* 4. Neither the name of the University nor the names of its contributors
	17	* may be used to endorse or promote products derived from this software
	18	* without specific prior written permission.
	19	*
	20	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	* SUCH DAMAGE.
	31	*/
	32
9385eb3d A	33	#if defined(LIBC_SCCS) && !defined(lint)
	34	static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93";
	35	#endif /* LIBC_SCCS and not lint */
	36	#include <sys/cdefs.h>
1f2f436a	37	__FBSDID("$FreeBSD: src/lib/libc/stdio/freopen.c,v 1.21 2008/04/17 22:17:54 jhb Exp $");
e9ce8d39	38
9385eb3d	39	#include "namespace.h"
e9ce8d39 A	40	#include <sys/types.h>
	41	#include <sys/stat.h>
	42	#include <fcntl.h>
	43	#include <errno.h>
1f2f436a	44	#include <limits.h>
e9ce8d39 A	45	#include <unistd.h>
	46	#include <stdio.h>
	47	#include <stdlib.h>
9385eb3d A	48	#include "un-namespace.h"
9385eb3d A	49	#include "libc_private.h"
e9ce8d39 A	50	#include "local.h"
e9ce8d39 A	51
9385eb3d A	52	/*
9385eb3d A	53	* Re-direct an existing, open (probably) file to some other file.
e9ce8d39 A	54	* ANSI is written such that the original file gets closed if at
	55	* all possible, no matter what.
	56	*/
	57	FILE *
	58	freopen(file, mode, fp)
9385eb3d A	59	const char * __restrict file;
	60	const char * __restrict mode;
	61	FILE *fp;
e9ce8d39	62	{
9385eb3d A	63	int f;
9385eb3d A	64	int dflags, flags, isopen, oflags, sverrno, wantfd;
e9ce8d39 A	65
e9ce8d39 A	66	if ((flags = __sflags(mode, &oflags)) == 0) {
1f2f436a	67	sverrno = errno;
e9ce8d39	68	(void) fclose(fp);
1f2f436a	69	errno = sverrno;
e9ce8d39 A	70	return (NULL);
	71	}
	72
23e20b00 A	73	pthread_once(&__sdidinit, __sinit);
23e20b00 A	74
9385eb3d A	75	FLOCKFILE(fp);
9385eb3d A	76
9385eb3d A	77	/*
	78	* If the filename is a NULL pointer, the caller is asking us to
	79	* re-open the same file with a different mode. We allow this only
	80	* if the modes are compatible.
	81	*/
	82	if (file == NULL) {
	83	/* See comment below regarding freopen() of closed files. */
	84	if (fp->_flags == 0) {
	85	FUNLOCKFILE(fp);
	86	errno = EINVAL;
	87	return (NULL);
	88	}
	89	if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) {
	90	sverrno = errno;
	91	fclose(fp);
	92	FUNLOCKFILE(fp);
	93	errno = sverrno;
	94	return (NULL);
	95	}
	96	if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) !=
	97	(oflags & O_ACCMODE)) {
	98	fclose(fp);
	99	FUNLOCKFILE(fp);
ad3c9f2a	100	errno = EBADF;
9385eb3d A	101	return (NULL);
9385eb3d A	102	}
1f2f436a A	103	if (fp->_flags & __SWR)
1f2f436a A	104	(void) __sflush(fp);
9385eb3d A	105	if ((oflags ^ dflags) & O_APPEND) {
	106	dflags &= ~O_APPEND;
	107	dflags \|= oflags & O_APPEND;
	108	if (_fcntl(fp->_file, F_SETFL, dflags) < 0) {
	109	sverrno = errno;
	110	fclose(fp);
	111	FUNLOCKFILE(fp);
	112	errno = sverrno;
	113	return (NULL);
	114	}
	115	}
	116	if (oflags & O_TRUNC)
1f2f436a A	117	(void) ftruncate(fp->_file, (off_t)0);
	118	if (!(oflags & O_APPEND))
	119	(void) _sseek(fp, (fpos_t)0, SEEK_SET);
9385eb3d A	120	f = fp->_file;
	121	isopen = 0;
	122	wantfd = -1;
	123	goto finish;
	124	}
	125
e9ce8d39 A	126	/*
	127	* There are actually programs that depend on being able to "freopen"
	128	* descriptors that weren't originally open. Keep this from breaking.
	129	* Remember whether the stream was open to begin with, and which file
	130	* descriptor (if any) was associated with it. If it was attached to
	131	* a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
	132	* should work. This is unnecessary if it was not a Unix file.
ad3c9f2a A	133	*
ad3c9f2a A	134	* For UNIX03, we always close if it was open.
e9ce8d39 A	135	*/
	136	if (fp->_flags == 0) {
	137	fp->_flags = __SEOF; /* hold on to it */
	138	isopen = 0;
	139	wantfd = -1;
	140	} else {
	141	/* flush the stream; ANSI doesn't require this. */
	142	if (fp->_flags & __SWR)
	143	(void) __sflush(fp);
	144	/* if close is NULL, closing is a no-op, hence pointless */
ad3c9f2a A	145	#if __DARWIN_UNIX03
	146	if (fp->_close)
	147	(void) (*fp->_close)(fp->_cookie);
	148	isopen = 0;
	149	wantfd = -1;
	150	#else /* !__DARWIN_UNIX03 */
e9ce8d39 A	151	isopen = fp->_close != NULL;
	152	if ((wantfd = fp->_file) < 0 && isopen) {
	153	(void) (*fp->_close)(fp->_cookie);
	154	isopen = 0;
	155	}
ad3c9f2a	156	#endif /* __DARWIN_UNIX03 */
e9ce8d39 A	157	}
	158
	159	/* Get a new descriptor to refer to the new file. */
9385eb3d	160	f = _open(file, oflags, DEFFILEMODE);
e9ce8d39 A	161	if (f < 0 && isopen) {
	162	/* If out of fd's close the old one and try again. */
	163	if (errno == ENFILE \|\| errno == EMFILE) {
	164	(void) (*fp->_close)(fp->_cookie);
	165	isopen = 0;
9385eb3d	166	f = _open(file, oflags, DEFFILEMODE);
e9ce8d39 A	167	}
	168	}
	169	sverrno = errno;
	170
9385eb3d	171	finish:
e9ce8d39 A	172	/*
	173	* Finish closing fp. Even if the open succeeded above, we cannot
	174	* keep fp->_base: it may be the wrong size. This loses the effect
	175	* of any setbuffer calls, but stdio has always done this before.
	176	*/
	177	if (isopen)
	178	(void) (*fp->_close)(fp->_cookie);
	179	if (fp->_flags & __SMBF)
	180	free((char *)fp->_bf._base);
	181	fp->_w = 0;
	182	fp->_r = 0;
	183	fp->_p = NULL;
	184	fp->_bf._base = NULL;
	185	fp->_bf._size = 0;
	186	fp->_lbfsize = 0;
	187	if (HASUB(fp))
	188	FREEUB(fp);
	189	fp->_ub._size = 0;
	190	if (HASLB(fp))
	191	FREELB(fp);
	192	fp->_lb._size = 0;
1f2f436a A	193	fp->_orientation = 0;
1f2f436a A	194	memset(&fp->_mbstate, 0, sizeof(mbstate_t));
e9ce8d39 A	195
e9ce8d39 A	196	if (f < 0) { /* did not get it after all */
9385eb3d	197	FUNLOCKFILE(fp);
23e20b00	198	__sfprelease(fp); /* set it free */
1f2f436a	199	errno = sverrno; /* restore in case _close clobbered */
e9ce8d39 A	200	return (NULL);
	201	}
	202
	203	/*
	204	* If reopening something that was open before on a real file, try
	205	* to maintain the descriptor. Various C library routines (perror)
	206	* assume stderr is always fd STDERR_FILENO, even if being freopen'd.
	207	*/
	208	if (wantfd >= 0 && f != wantfd) {
9385eb3d A	209	if (_dup2(f, wantfd) >= 0) {
9385eb3d A	210	(void)_close(f);
e9ce8d39 A	211	f = wantfd;
	212	}
	213	}
	214
1f2f436a A	215	/*
	216	* File descriptors are a full int, but _file is only a short.
	217	* If we get a valid file descriptor that is greater than
	218	* SHRT_MAX, then the fd will get sign-extended into an
	219	* invalid file descriptor. Handle this case by failing the
	220	* open.
	221	*/
	222	if (f > SHRT_MAX) {
1f2f436a	223	FUNLOCKFILE(fp);
23e20b00	224	__sfprelease(fp); /* set it free */
1f2f436a A	225	errno = EMFILE;
	226	return (NULL);
	227	}
	228
e9ce8d39 A	229	fp->_flags = flags;
	230	fp->_file = f;
	231	fp->_cookie = fp;
	232	fp->_read = __sread;
	233	fp->_write = __swrite;
	234	fp->_seek = __sseek;
	235	fp->_close = __sclose;
1f2f436a A	236	/*
	237	* When opening in append mode, even though we use O_APPEND,
	238	* we need to seek to the end so that ftell() gets the right
	239	* answer. If the user then alters the seek pointer, or
	240	* the file extends, this will fail, but there is not much
	241	* we can do about this. (We could set __SAPP and check in
	242	* fseek and ftell.)
	243	*/
	244	if (oflags & O_APPEND)
	245	(void) _sseek(fp, (fpos_t)0, SEEK_END);
9385eb3d	246	FUNLOCKFILE(fp);
e9ce8d39 A	247	return (fp);
e9ce8d39 A	248	}