[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.
 * 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 1.44 2008/04/17 22:17:54 jhb 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->_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->_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;
	memset(&fp->_mbstate, 0, sizeof(mbstate_t));
	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);
	if (ltest && ret > LONG_MAX) {
		fp->_flags |= __SERR;
		errno = EOVERFLOW;
		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->_mbstate, 0, sizeof(mbstate_t));
	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.
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[] = "@(#)fseek.c 8.3 (Berkeley) 1/2/94";
	35	#endif /* LIBC_SCCS and not lint */
	36	#include <sys/cdefs.h>
1f2f436a	37	__FBSDID("$FreeBSD: src/lib/libc/stdio/fseek.c,v 1.44 2008/04/17 22:17:54 jhb Exp $");
e9ce8d39	38
9385eb3d	39	#include "namespace.h"
e9ce8d39 A	40	#include <sys/types.h>
e9ce8d39 A	41	#include <sys/stat.h>
9385eb3d	42	#include <errno.h>
e9ce8d39	43	#include <fcntl.h>
9385eb3d	44	#include <limits.h>
e9ce8d39 A	45	#include <stdio.h>
e9ce8d39 A	46	#include <stdlib.h>
9385eb3d	47	#include "un-namespace.h"
e9ce8d39	48	#include "local.h"
9385eb3d	49	#include "libc_private.h"
e9ce8d39 A	50
	51	#define POS_ERR (-(fpos_t)1)
	52
	53	int
	54	fseek(fp, offset, whence)
9385eb3d	55	FILE *fp;
e9ce8d39 A	56	long offset;
	57	int whence;
	58	{
9385eb3d A	59	int ret;
	60	int serrno = errno;
	61
	62	/* make sure stdio is set up */
	63	if (!__sdidinit)
	64	__sinit();
	65
	66	FLOCKFILE(fp);
	67	ret = _fseeko(fp, (off_t)offset, whence, 1);
	68	FUNLOCKFILE(fp);
	69	if (ret == 0)
	70	errno = serrno;
	71	return (ret);
e9ce8d39 A	72	}
e9ce8d39 A	73
9385eb3d A	74	int
	75	fseeko(fp, offset, whence)
	76	FILE *fp;
	77	off_t offset;
	78	int whence;
	79	{
	80	int ret;
	81	int serrno = errno;
	82
	83	/* make sure stdio is set up */
	84	if (!__sdidinit)
	85	__sinit();
	86
	87	FLOCKFILE(fp);
	88	ret = _fseeko(fp, offset, whence, 0);
	89	FUNLOCKFILE(fp);
	90	if (ret == 0)
	91	errno = serrno;
	92	return (ret);
	93	}
e9ce8d39 A	94
	95	/*
	96	* Seek the given file to the given offset.
	97	* `Whence' must be one of the three SEEK_* macros.
	98	*/
	99	int
9385eb3d A	100	_fseeko(fp, offset, whence, ltest)
9385eb3d A	101	FILE *fp;
e9ce8d39 A	102	off_t offset;
e9ce8d39 A	103	int whence;
9385eb3d	104	int ltest;
e9ce8d39	105	{
9385eb3d A	106	fpos_t (seekfn)(void , fpos_t, int);
9385eb3d A	107	fpos_t target, curoff, ret;
e9ce8d39 A	108	size_t n;
	109	struct stat st;
	110	int havepos;
	111
e9ce8d39 A	112	/*
	113	* Have to be able to seek.
	114	*/
	115	if ((seekfn = fp->_seek) == NULL) {
9385eb3d A	116	errno = ESPIPE; /* historic practice */
9385eb3d A	117	return (-1);
e9ce8d39 A	118	}
	119
	120	/*
	121	* Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
	122	* After this, whence is either SEEK_SET or SEEK_END.
	123	*/
	124	switch (whence) {
	125
	126	case SEEK_CUR:
	127	/*
	128	* In order to seek relative to the current stream offset,
9385eb3d	129	* we have to first find the current stream offset via
e9ce8d39 A	130	* ftell (see ftell for details).
e9ce8d39 A	131	*/
9385eb3d A	132	if (_ftello(fp, &curoff))
	133	return (-1);
	134	if (curoff < 0) {
	135	/* Unspecified position because of ungetc() at 0 */
	136	errno = ESPIPE;
	137	return (-1);
	138	}
	139	if (offset > 0 && curoff > OFF_MAX - offset) {
	140	errno = EOVERFLOW;
	141	return (-1);
e9ce8d39	142	}
e9ce8d39	143	offset += curoff;
9385eb3d A	144	if (offset < 0) {
	145	errno = EINVAL;
	146	return (-1);
	147	}
	148	if (ltest && offset > LONG_MAX) {
	149	errno = EOVERFLOW;
	150	return (-1);
	151	}
e9ce8d39 A	152	whence = SEEK_SET;
	153	havepos = 1;
	154	break;
	155
	156	case SEEK_SET:
9385eb3d A	157	if (offset < 0) {
	158	errno = EINVAL;
	159	return (-1);
	160	}
e9ce8d39 A	161	case SEEK_END:
	162	curoff = 0; /* XXX just to keep gcc quiet */
	163	havepos = 0;
	164	break;
	165
	166	default:
	167	errno = EINVAL;
9385eb3d	168	return (-1);
e9ce8d39 A	169	}
	170
	171	/*
	172	* Can only optimise if:
	173	* reading (and not reading-and-writing);
	174	* not unbuffered; and
	175	* this is a `regular' Unix file (and hence seekfn==__sseek).
	176	* We must check __NBF first, because it is possible to have __NBF
	177	* and __SOPT both set.
	178	*/
	179	if (fp->_bf._base == NULL)
	180	__smakebuf(fp);
	181	if (fp->_flags & (__SWR \| __SRW \| __SNBF \| __SNPT))
	182	goto dumb;
	183	if ((fp->_flags & __SOPT) == 0) {
	184	if (seekfn != __sseek \|\|
9385eb3d	185	fp->_file < 0 \|\| _fstat(fp->_file, &st) \|\|
e9ce8d39 A	186	(st.st_mode & S_IFMT) != S_IFREG) {
	187	fp->_flags \|= __SNPT;
	188	goto dumb;
	189	}
	190	fp->_blksize = st.st_blksize;
	191	fp->_flags \|= __SOPT;
	192	}
	193
	194	/*
	195	* We are reading; we can try to optimise.
	196	* Figure out where we are going and where we are now.
	197	*/
	198	if (whence == SEEK_SET)
	199	target = offset;
	200	else {
9385eb3d	201	if (_fstat(fp->_file, &st))
e9ce8d39	202	goto dumb;
9385eb3d A	203	if (offset > 0 && st.st_size > OFF_MAX - offset) {
	204	errno = EOVERFLOW;
	205	return (-1);
	206	}
e9ce8d39	207	target = st.st_size + offset;
9385eb3d A	208	if ((off_t)target < 0) {
	209	errno = EINVAL;
	210	return (-1);
	211	}
	212	if (ltest && (off_t)target > LONG_MAX) {
	213	errno = EOVERFLOW;
	214	return (-1);
e9ce8d39	215	}
e9ce8d39 A	216	}
e9ce8d39 A	217
9385eb3d A	218	if (!havepos && _ftello(fp, &curoff))
	219	goto dumb;
	220
	221	/*
	222	* (If the buffer was modified, we have to
	223	* skip this; see fgetln.c.)
	224	*/
	225	if (fp->_flags & __SMOD)
	226	goto abspos;
	227
e9ce8d39 A	228	/*
	229	* Compute the number of bytes in the input buffer (pretending
	230	* that any ungetc() input has been discarded). Adjust current
	231	* offset backwards by this count so that it represents the
	232	* file offset for the first byte in the current input buffer.
	233	*/
	234	if (HASUB(fp)) {
	235	curoff += fp->_r; /* kill off ungetc */
1f2f436a	236	n = fp->_up - fp->_bf._base;
e9ce8d39 A	237	curoff -= n;
	238	n += fp->_ur;
	239	} else {
	240	n = fp->_p - fp->_bf._base;
	241	curoff -= n;
	242	n += fp->_r;
	243	}
	244
	245	/*
	246	* If the target offset is within the current buffer,
	247	* simply adjust the pointers, clear EOF, undo ungetc(),
9385eb3d	248	* and return.
e9ce8d39	249	*/
9385eb3d A	250	if (target >= curoff && target < curoff + n) {
9385eb3d A	251	size_t o = target - curoff;
e9ce8d39 A	252
	253	fp->_p = fp->_bf._base + o;
	254	fp->_r = n - o;
	255	if (HASUB(fp))
	256	FREEUB(fp);
	257	fp->_flags &= ~__SEOF;
1f2f436a	258	memset(&fp->_mbstate, 0, sizeof(mbstate_t));
e9ce8d39 A	259	return (0);
	260	}
	261
9385eb3d	262	abspos:
e9ce8d39 A	263	/*
	264	* The place we want to get to is not within the current buffer,
	265	* but we can still be kind to the kernel copyout mechanism.
	266	* By aligning the file offset to a block boundary, we can let
	267	* the kernel use the VM hardware to map pages instead of
	268	* copying bytes laboriously. Using a block boundary also
	269	* ensures that we only read one block, rather than two.
	270	*/
	271	curoff = target & ~(fp->_blksize - 1);
9385eb3d	272	if (_sseek(fp, curoff, SEEK_SET) == POS_ERR)
e9ce8d39 A	273	goto dumb;
	274	fp->_r = 0;
	275	fp->_p = fp->_bf._base;
	276	if (HASUB(fp))
	277	FREEUB(fp);
e9ce8d39 A	278	n = target - curoff;
	279	if (n) {
	280	if (__srefill(fp) \|\| fp->_r < n)
	281	goto dumb;
	282	fp->_p += n;
	283	fp->_r -= n;
	284	}
9385eb3d	285	fp->_flags &= ~__SEOF;
1f2f436a	286	memset(&fp->_mbstate, 0, sizeof(mbstate_t));
e9ce8d39 A	287	return (0);
	288
	289	/*
	290	* We get here if we cannot optimise the seek ... just
	291	* do it. Allow the seek function to change fp->_bf._base.
	292	*/
	293	dumb:
	294	if (__sflush(fp) \|\|
9385eb3d A	295	(ret = _sseek(fp, (fpos_t)offset, whence)) == POS_ERR)
9385eb3d A	296	return (-1);
1f2f436a A	297	if (ltest && ret > LONG_MAX) {
	298	fp->_flags \|= __SERR;
	299	errno = EOVERFLOW;
	300	return (-1);
	301	}
e9ce8d39 A	302	/* success: clear EOF indicator and discard ungetc() data */
	303	if (HASUB(fp))
	304	FREEUB(fp);
	305	fp->_p = fp->_bf._base;
	306	fp->_r = 0;
	307	/* fp->_w = 0; / / unnecessary (I think...) */
	308	fp->_flags &= ~__SEOF;
1f2f436a	309	memset(&fp->_mbstate, 0, sizeof(mbstate_t));
e9ce8d39 A	310	return (0);
e9ce8d39 A	311	}