[apple/libc.git] / stdio / FreeBSD / fseek.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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 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[] = "@(#)fseek.c	8.3 (Berkeley) 1/2/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/stdio/fseek.c,v 1.41 2004/05/22 15:19:41 tjr Exp $");

#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include "un-namespace.h"
#include "local.h"
#include "libc_private.h"

#define	POS_ERR	(-(fpos_t)1)

int
fseek(fp, offset, whence)
	FILE *fp;
	long offset;
	int whence;
{
	int ret;
	int serrno = errno;

	/* make sure stdio is set up */
	if (!__sdidinit)
		__sinit();

	FLOCKFILE(fp);
	ret = _fseeko(fp, (off_t)offset, whence, 1);
	FUNLOCKFILE(fp);
	if (ret == 0)
		errno = serrno;
	return (ret);
}

int
fseeko(fp, offset, whence)
	FILE *fp;
	off_t offset;
	int whence;
{
	int ret;
	int serrno = errno;

	/* make sure stdio is set up */
	if (!__sdidinit)
		__sinit();

	FLOCKFILE(fp);
	ret = _fseeko(fp, offset, whence, 0);
	FUNLOCKFILE(fp);
	if (ret == 0)
		errno = serrno;
	return (ret);
}

/*
 * Seek the given file to the given offset.
 * `Whence' must be one of the three SEEK_* macros.
 */
int
_fseeko(fp, offset, whence, ltest)
	FILE *fp;
	off_t offset;
	int whence;
	int ltest;
{
	fpos_t (*seekfn)(void *, fpos_t, int);
	fpos_t target, curoff, ret;
	size_t n;
	struct stat st;
	int havepos;

	/*
	 * Have to be able to seek.
	 */
	if ((seekfn = fp->_seek) == NULL) {
		errno = ESPIPE;		/* historic practice */
		return (-1);
	}

	/*
	 * Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
	 * After this, whence is either SEEK_SET or SEEK_END.
	 */
	switch (whence) {

	case SEEK_CUR:
		/*
		 * In order to seek relative to the current stream offset,
		 * we have to first find the current stream offset via
		 * ftell (see ftell for details).
		 */
		if (_ftello(fp, &curoff))
			return (-1);
		if (curoff < 0) {
			/* Unspecified position because of ungetc() at 0 */
			errno = ESPIPE;
			return (-1);
		}
		if (offset > 0 && curoff > OFF_MAX - offset) {
			errno = EOVERFLOW;
			return (-1);
		}
		offset += curoff;
		if (offset < 0) {
			errno = EINVAL;
			return (-1);
		}
		if (ltest && offset > LONG_MAX) {
			errno = EOVERFLOW;
			return (-1);
		}
		whence = SEEK_SET;
		havepos = 1;
		break;

	case SEEK_SET:
		if (offset < 0) {
			errno = EINVAL;
			return (-1);
		}
	case SEEK_END:
		curoff = 0;		/* XXX just to keep gcc quiet */
		havepos = 0;
		break;

	default:
		errno = EINVAL;
		return (-1);
	}

	/*
	 * Can only optimise if:
	 *	reading (and not reading-and-writing);
	 *	not unbuffered; and
	 *	this is a `regular' Unix file (and hence seekfn==__sseek).
	 * We must check __NBF first, because it is possible to have __NBF
	 * and __SOPT both set.
	 */
	if (fp->_bf._base == NULL)
		__smakebuf(fp);
	if (fp->_flags & (__SWR | __SRW | __SNBF | __SNPT))
		goto dumb;
	if ((fp->_flags & __SOPT) == 0) {
		if (seekfn != __sseek ||
		    fp->_file < 0 || _fstat(fp->_file, &st) ||
		    (st.st_mode & S_IFMT) != S_IFREG) {
			fp->_flags |= __SNPT;
			goto dumb;
		}
		fp->_blksize = st.st_blksize;
		fp->_flags |= __SOPT;
	}

	/*
	 * We are reading; we can try to optimise.
	 * Figure out where we are going and where we are now.
	 */
	if (whence == SEEK_SET)
		target = offset;
	else {
		if (_fstat(fp->_file, &st))
			goto dumb;
		if (offset > 0 && st.st_size > OFF_MAX - offset) {
			errno = EOVERFLOW;
			return (-1);
		}
		target = st.st_size + offset;
		if ((off_t)target < 0) {
			errno = EINVAL;
			return (-1);
		}
		if (ltest && (off_t)target > LONG_MAX) {
			errno = EOVERFLOW;
			return (-1);
		}
	}

	if (!havepos && _ftello(fp, &curoff))
		goto dumb;

	/*
	 * (If the buffer was modified, we have to
	 * skip this; see fgetln.c.)
	 */
	if (fp->_flags & __SMOD)
		goto abspos;

	/*
	 * Compute the number of bytes in the input buffer (pretending
	 * that any ungetc() input has been discarded).  Adjust current
	 * offset backwards by this count so that it represents the
	 * file offset for the first byte in the current input buffer.
	 */
	if (HASUB(fp)) {
		curoff += fp->_r;	/* kill off ungetc */
		n = fp->_extra->_up - fp->_bf._base;
		curoff -= n;
		n += fp->_ur;
	} else {
		n = fp->_p - fp->_bf._base;
		curoff -= n;
		n += fp->_r;
	}

	/*
	 * If the target offset is within the current buffer,
	 * simply adjust the pointers, clear EOF, undo ungetc(),
	 * and return.
	 */
	if (target >= curoff && target < curoff + n) {
		size_t o = target - curoff;

		fp->_p = fp->_bf._base + o;
		fp->_r = n - o;
		if (HASUB(fp))
			FREEUB(fp);
		fp->_flags &= ~__SEOF;
		memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
		return (0);
	}

abspos:
	/*
	 * The place we want to get to is not within the current buffer,
	 * but we can still be kind to the kernel copyout mechanism.
	 * By aligning the file offset to a block boundary, we can let
	 * the kernel use the VM hardware to map pages instead of
	 * copying bytes laboriously.  Using a block boundary also
	 * ensures that we only read one block, rather than two.
	 */
	curoff = target & ~(fp->_blksize - 1);
	if (_sseek(fp, curoff, SEEK_SET) == POS_ERR)
		goto dumb;
	fp->_r = 0;
	fp->_p = fp->_bf._base;
	if (HASUB(fp))
		FREEUB(fp);
	n = target - curoff;
	if (n) {
		if (__srefill(fp) || fp->_r < n)
			goto dumb;
		fp->_p += n;
		fp->_r -= n;
	}
	fp->_flags &= ~__SEOF;
	return (0);

	/*
	 * We get here if we cannot optimise the seek ... just
	 * do it.  Allow the seek function to change fp->_bf._base.
	 */
dumb:
	if (__sflush(fp) ||
	    (ret = _sseek(fp, (fpos_t)offset, whence)) == POS_ERR)
		return (-1);
	/* success: clear EOF indicator and discard ungetc() data */
	if (HASUB(fp))
		FREEUB(fp);
	fp->_p = fp->_bf._base;
	fp->_r = 0;
	/* fp->_w = 0; */	/* unnecessary (I think...) */
	fp->_flags &= ~__SEOF;
	memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
	if (ltest && ret > LONG_MAX) {
		fp->_flags |= __SERR;
		errno = EOVERFLOW;
		return (-1);
	}
	return (0);
}
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.
	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
9385eb3d A	37	#if defined(LIBC_SCCS) && !defined(lint)
	38	static char sccsid[] = "@(#)fseek.c 8.3 (Berkeley) 1/2/94";
	39	#endif /* LIBC_SCCS and not lint */
	40	#include <sys/cdefs.h>
3d9156a7	41	__FBSDID("$FreeBSD: src/lib/libc/stdio/fseek.c,v 1.41 2004/05/22 15:19:41 tjr Exp $");
e9ce8d39	42
9385eb3d	43	#include "namespace.h"
e9ce8d39 A	44	#include <sys/types.h>
e9ce8d39 A	45	#include <sys/stat.h>
9385eb3d	46	#include <errno.h>
e9ce8d39	47	#include <fcntl.h>
9385eb3d	48	#include <limits.h>
e9ce8d39 A	49	#include <stdio.h>
e9ce8d39 A	50	#include <stdlib.h>
9385eb3d	51	#include "un-namespace.h"
e9ce8d39	52	#include "local.h"
9385eb3d	53	#include "libc_private.h"
e9ce8d39 A	54
	55	#define POS_ERR (-(fpos_t)1)
	56
	57	int
	58	fseek(fp, offset, whence)
9385eb3d	59	FILE *fp;
e9ce8d39 A	60	long offset;
	61	int whence;
	62	{
9385eb3d A	63	int ret;
	64	int serrno = errno;
	65
	66	/* make sure stdio is set up */
	67	if (!__sdidinit)
	68	__sinit();
	69
	70	FLOCKFILE(fp);
	71	ret = _fseeko(fp, (off_t)offset, whence, 1);
	72	FUNLOCKFILE(fp);
	73	if (ret == 0)
	74	errno = serrno;
	75	return (ret);
e9ce8d39 A	76	}
e9ce8d39 A	77
9385eb3d A	78	int
	79	fseeko(fp, offset, whence)
	80	FILE *fp;
	81	off_t offset;
	82	int whence;
	83	{
	84	int ret;
	85	int serrno = errno;
	86
	87	/* make sure stdio is set up */
	88	if (!__sdidinit)
	89	__sinit();
	90
	91	FLOCKFILE(fp);
	92	ret = _fseeko(fp, offset, whence, 0);
	93	FUNLOCKFILE(fp);
	94	if (ret == 0)
	95	errno = serrno;
	96	return (ret);
	97	}
e9ce8d39 A	98
	99	/*
	100	* Seek the given file to the given offset.
	101	* `Whence' must be one of the three SEEK_* macros.
	102	*/
	103	int
9385eb3d A	104	_fseeko(fp, offset, whence, ltest)
9385eb3d A	105	FILE *fp;
e9ce8d39 A	106	off_t offset;
e9ce8d39 A	107	int whence;
9385eb3d	108	int ltest;
e9ce8d39	109	{
9385eb3d A	110	fpos_t (seekfn)(void , fpos_t, int);
9385eb3d A	111	fpos_t target, curoff, ret;
e9ce8d39 A	112	size_t n;
	113	struct stat st;
	114	int havepos;
	115
e9ce8d39 A	116	/*
	117	* Have to be able to seek.
	118	*/
	119	if ((seekfn = fp->_seek) == NULL) {
9385eb3d A	120	errno = ESPIPE; /* historic practice */
9385eb3d A	121	return (-1);
e9ce8d39 A	122	}
	123
	124	/*
	125	* Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
	126	* After this, whence is either SEEK_SET or SEEK_END.
	127	*/
	128	switch (whence) {
	129
	130	case SEEK_CUR:
	131	/*
	132	* In order to seek relative to the current stream offset,
9385eb3d	133	* we have to first find the current stream offset via
e9ce8d39 A	134	* ftell (see ftell for details).
e9ce8d39 A	135	*/
9385eb3d A	136	if (_ftello(fp, &curoff))
	137	return (-1);
	138	if (curoff < 0) {
	139	/* Unspecified position because of ungetc() at 0 */
	140	errno = ESPIPE;
	141	return (-1);
	142	}
	143	if (offset > 0 && curoff > OFF_MAX - offset) {
	144	errno = EOVERFLOW;
	145	return (-1);
e9ce8d39	146	}
e9ce8d39	147	offset += curoff;
9385eb3d A	148	if (offset < 0) {
	149	errno = EINVAL;
	150	return (-1);
	151	}
	152	if (ltest && offset > LONG_MAX) {
	153	errno = EOVERFLOW;
	154	return (-1);
	155	}
e9ce8d39 A	156	whence = SEEK_SET;
	157	havepos = 1;
	158	break;
	159
	160	case SEEK_SET:
9385eb3d A	161	if (offset < 0) {
	162	errno = EINVAL;
	163	return (-1);
	164	}
e9ce8d39 A	165	case SEEK_END:
	166	curoff = 0; /* XXX just to keep gcc quiet */
	167	havepos = 0;
	168	break;
	169
	170	default:
	171	errno = EINVAL;
9385eb3d	172	return (-1);
e9ce8d39 A	173	}
	174
	175	/*
	176	* Can only optimise if:
	177	* reading (and not reading-and-writing);
	178	* not unbuffered; and
	179	* this is a `regular' Unix file (and hence seekfn==__sseek).
	180	* We must check __NBF first, because it is possible to have __NBF
	181	* and __SOPT both set.
	182	*/
	183	if (fp->_bf._base == NULL)
	184	__smakebuf(fp);
	185	if (fp->_flags & (__SWR \| __SRW \| __SNBF \| __SNPT))
	186	goto dumb;
	187	if ((fp->_flags & __SOPT) == 0) {
	188	if (seekfn != __sseek \|\|
9385eb3d	189	fp->_file < 0 \|\| _fstat(fp->_file, &st) \|\|
e9ce8d39 A	190	(st.st_mode & S_IFMT) != S_IFREG) {
	191	fp->_flags \|= __SNPT;
	192	goto dumb;
	193	}
	194	fp->_blksize = st.st_blksize;
	195	fp->_flags \|= __SOPT;
	196	}
	197
	198	/*
	199	* We are reading; we can try to optimise.
	200	* Figure out where we are going and where we are now.
	201	*/
	202	if (whence == SEEK_SET)
	203	target = offset;
	204	else {
9385eb3d	205	if (_fstat(fp->_file, &st))
e9ce8d39	206	goto dumb;
9385eb3d A	207	if (offset > 0 && st.st_size > OFF_MAX - offset) {
	208	errno = EOVERFLOW;
	209	return (-1);
	210	}
e9ce8d39	211	target = st.st_size + offset;
9385eb3d A	212	if ((off_t)target < 0) {
	213	errno = EINVAL;
	214	return (-1);
	215	}
	216	if (ltest && (off_t)target > LONG_MAX) {
	217	errno = EOVERFLOW;
	218	return (-1);
e9ce8d39	219	}
e9ce8d39 A	220	}
e9ce8d39 A	221
9385eb3d A	222	if (!havepos && _ftello(fp, &curoff))
	223	goto dumb;
	224
	225	/*
	226	* (If the buffer was modified, we have to
	227	* skip this; see fgetln.c.)
	228	*/
	229	if (fp->_flags & __SMOD)
	230	goto abspos;
	231
e9ce8d39 A	232	/*
	233	* Compute the number of bytes in the input buffer (pretending
	234	* that any ungetc() input has been discarded). Adjust current
	235	* offset backwards by this count so that it represents the
	236	* file offset for the first byte in the current input buffer.
	237	*/
	238	if (HASUB(fp)) {
	239	curoff += fp->_r; /* kill off ungetc */
9385eb3d	240	n = fp->_extra->_up - fp->_bf._base;
e9ce8d39 A	241	curoff -= n;
	242	n += fp->_ur;
	243	} else {
	244	n = fp->_p - fp->_bf._base;
	245	curoff -= n;
	246	n += fp->_r;
	247	}
	248
	249	/*
	250	* If the target offset is within the current buffer,
	251	* simply adjust the pointers, clear EOF, undo ungetc(),
9385eb3d	252	* and return.
e9ce8d39	253	*/
9385eb3d A	254	if (target >= curoff && target < curoff + n) {
9385eb3d A	255	size_t o = target - curoff;
e9ce8d39 A	256
	257	fp->_p = fp->_bf._base + o;
	258	fp->_r = n - o;
	259	if (HASUB(fp))
	260	FREEUB(fp);
	261	fp->_flags &= ~__SEOF;
3d9156a7	262	memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
e9ce8d39 A	263	return (0);
	264	}
	265
9385eb3d	266	abspos:
e9ce8d39 A	267	/*
	268	* The place we want to get to is not within the current buffer,
	269	* but we can still be kind to the kernel copyout mechanism.
	270	* By aligning the file offset to a block boundary, we can let
	271	* the kernel use the VM hardware to map pages instead of
	272	* copying bytes laboriously. Using a block boundary also
	273	* ensures that we only read one block, rather than two.
	274	*/
	275	curoff = target & ~(fp->_blksize - 1);
9385eb3d	276	if (_sseek(fp, curoff, SEEK_SET) == POS_ERR)
e9ce8d39 A	277	goto dumb;
	278	fp->_r = 0;
	279	fp->_p = fp->_bf._base;
	280	if (HASUB(fp))
	281	FREEUB(fp);
e9ce8d39 A	282	n = target - curoff;
	283	if (n) {
	284	if (__srefill(fp) \|\| fp->_r < n)
	285	goto dumb;
	286	fp->_p += n;
	287	fp->_r -= n;
	288	}
9385eb3d	289	fp->_flags &= ~__SEOF;
e9ce8d39 A	290	return (0);
	291
	292	/*
	293	* We get here if we cannot optimise the seek ... just
	294	* do it. Allow the seek function to change fp->_bf._base.
	295	*/
	296	dumb:
	297	if (__sflush(fp) \|\|
9385eb3d A	298	(ret = _sseek(fp, (fpos_t)offset, whence)) == POS_ERR)
9385eb3d A	299	return (-1);
e9ce8d39 A	300	/* success: clear EOF indicator and discard ungetc() data */
	301	if (HASUB(fp))
	302	FREEUB(fp);
	303	fp->_p = fp->_bf._base;
	304	fp->_r = 0;
	305	/* fp->_w = 0; / / unnecessary (I think...) */
	306	fp->_flags &= ~__SEOF;
3d9156a7	307	memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
9385eb3d A	308	if (ltest && ret > LONG_MAX) {
	309	fp->_flags \|= __SERR;
	310	errno = EOVERFLOW;
	311	return (-1);
	312	}
e9ce8d39 A	313	return (0);
e9ce8d39 A	314	}