[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);
	}

	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);
		}
		if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) !=
		    (oflags & O_ACCMODE)) {
			fclose(fp);
			FUNLOCKFILE(fp);
			errno = EINVAL;
			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.
	 */
	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 (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 */
		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 && 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) {
		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);
}
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
9385eb3d A	73	FLOCKFILE(fp);
9385eb3d A	74
e9ce8d39 A	75	if (!__sdidinit)
	76	__sinit();
	77
9385eb3d A	78	/*
	79	* If the filename is a NULL pointer, the caller is asking us to
	80	* re-open the same file with a different mode. We allow this only
	81	* if the modes are compatible.
	82	*/
	83	if (file == NULL) {
	84	/* See comment below regarding freopen() of closed files. */
	85	if (fp->_flags == 0) {
	86	FUNLOCKFILE(fp);
	87	errno = EINVAL;
	88	return (NULL);
	89	}
	90	if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) {
	91	sverrno = errno;
	92	fclose(fp);
	93	FUNLOCKFILE(fp);
	94	errno = sverrno;
	95	return (NULL);
	96	}
	97	if ((dflags & O_ACCMODE) != O_RDWR && (dflags & O_ACCMODE) !=
	98	(oflags & O_ACCMODE)) {
	99	fclose(fp);
	100	FUNLOCKFILE(fp);
	101	errno = EINVAL;
	102	return (NULL);
	103	}
1f2f436a A	104	if (fp->_flags & __SWR)
1f2f436a A	105	(void) __sflush(fp);
9385eb3d A	106	if ((oflags ^ dflags) & O_APPEND) {
	107	dflags &= ~O_APPEND;
	108	dflags \|= oflags & O_APPEND;
	109	if (_fcntl(fp->_file, F_SETFL, dflags) < 0) {
	110	sverrno = errno;
	111	fclose(fp);
	112	FUNLOCKFILE(fp);
	113	errno = sverrno;
	114	return (NULL);
	115	}
	116	}
	117	if (oflags & O_TRUNC)
1f2f436a A	118	(void) ftruncate(fp->_file, (off_t)0);
	119	if (!(oflags & O_APPEND))
	120	(void) _sseek(fp, (fpos_t)0, SEEK_SET);
9385eb3d A	121	f = fp->_file;
	122	isopen = 0;
	123	wantfd = -1;
	124	goto finish;
	125	}
	126
e9ce8d39 A	127	/*
	128	* There are actually programs that depend on being able to "freopen"
	129	* descriptors that weren't originally open. Keep this from breaking.
	130	* Remember whether the stream was open to begin with, and which file
	131	* descriptor (if any) was associated with it. If it was attached to
	132	* a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
	133	* should work. This is unnecessary if it was not a Unix file.
	134	*/
	135	if (fp->_flags == 0) {
	136	fp->_flags = __SEOF; /* hold on to it */
	137	isopen = 0;
	138	wantfd = -1;
	139	} else {
	140	/* flush the stream; ANSI doesn't require this. */
	141	if (fp->_flags & __SWR)
	142	(void) __sflush(fp);
	143	/* if close is NULL, closing is a no-op, hence pointless */
	144	isopen = fp->_close != NULL;
	145	if ((wantfd = fp->_file) < 0 && isopen) {
	146	(void) (*fp->_close)(fp->_cookie);
	147	isopen = 0;
	148	}
	149	}
	150
	151	/* Get a new descriptor to refer to the new file. */
9385eb3d	152	f = _open(file, oflags, DEFFILEMODE);
e9ce8d39 A	153	if (f < 0 && isopen) {
	154	/* If out of fd's close the old one and try again. */
	155	if (errno == ENFILE \|\| errno == EMFILE) {
	156	(void) (*fp->_close)(fp->_cookie);
	157	isopen = 0;
9385eb3d	158	f = _open(file, oflags, DEFFILEMODE);
e9ce8d39 A	159	}
	160	}
	161	sverrno = errno;
	162
9385eb3d	163	finish:
e9ce8d39 A	164	/*
	165	* Finish closing fp. Even if the open succeeded above, we cannot
	166	* keep fp->_base: it may be the wrong size. This loses the effect
	167	* of any setbuffer calls, but stdio has always done this before.
	168	*/
	169	if (isopen)
	170	(void) (*fp->_close)(fp->_cookie);
	171	if (fp->_flags & __SMBF)
	172	free((char *)fp->_bf._base);
	173	fp->_w = 0;
	174	fp->_r = 0;
	175	fp->_p = NULL;
	176	fp->_bf._base = NULL;
	177	fp->_bf._size = 0;
	178	fp->_lbfsize = 0;
	179	if (HASUB(fp))
	180	FREEUB(fp);
	181	fp->_ub._size = 0;
	182	if (HASLB(fp))
	183	FREELB(fp);
	184	fp->_lb._size = 0;
1f2f436a A	185	fp->_orientation = 0;
1f2f436a A	186	memset(&fp->_mbstate, 0, sizeof(mbstate_t));
e9ce8d39 A	187
	188	if (f < 0) { /* did not get it after all */
	189	fp->_flags = 0; /* set it free */
9385eb3d	190	FUNLOCKFILE(fp);
1f2f436a	191	errno = sverrno; /* restore in case _close clobbered */
e9ce8d39 A	192	return (NULL);
	193	}
	194
	195	/*
	196	* If reopening something that was open before on a real file, try
	197	* to maintain the descriptor. Various C library routines (perror)
	198	* assume stderr is always fd STDERR_FILENO, even if being freopen'd.
	199	*/
	200	if (wantfd >= 0 && f != wantfd) {
9385eb3d A	201	if (_dup2(f, wantfd) >= 0) {
9385eb3d A	202	(void)_close(f);
e9ce8d39 A	203	f = wantfd;
	204	}
	205	}
	206
1f2f436a A	207	/*
	208	* File descriptors are a full int, but _file is only a short.
	209	* If we get a valid file descriptor that is greater than
	210	* SHRT_MAX, then the fd will get sign-extended into an
	211	* invalid file descriptor. Handle this case by failing the
	212	* open.
	213	*/
	214	if (f > SHRT_MAX) {
	215	fp->_flags = 0; /* set it free */
	216	FUNLOCKFILE(fp);
	217	errno = EMFILE;
	218	return (NULL);
	219	}
	220
e9ce8d39 A	221	fp->_flags = flags;
	222	fp->_file = f;
	223	fp->_cookie = fp;
	224	fp->_read = __sread;
	225	fp->_write = __swrite;
	226	fp->_seek = __sseek;
	227	fp->_close = __sclose;
1f2f436a A	228	/*
	229	* When opening in append mode, even though we use O_APPEND,
	230	* we need to seek to the end so that ftell() gets the right
	231	* answer. If the user then alters the seek pointer, or
	232	* the file extends, this will fail, but there is not much
	233	* we can do about this. (We could set __SAPP and check in
	234	* fseek and ftell.)
	235	*/
	236	if (oflags & O_APPEND)
	237	(void) _sseek(fp, (fpos_t)0, SEEK_END);
9385eb3d	238	FUNLOCKFILE(fp);
e9ce8d39 A	239	return (fp);
e9ce8d39 A	240	}