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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libc/stdio/fseek.c	Lines:	19	95	20.0 %
Date:	2017-11-13	Branches:	10	92	10.9 %


/*	$OpenBSD: fseek.c,v 1.12 2015/08/31 02:53:57 guenther Exp $ */
/*-
 * 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. 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.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include "local.h"

#define	POS_ERR	(-(fpos_t)1)

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

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

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

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

	case SEEK_CUR:
		/*
		 * In order to seek relative to the current stream offset,
		 * we have to first find the current stream offset a la
		 * ftell (see ftell for details).
		 */
		__sflush(fp);	/* may adjust seek offset on append stream */
		if (fp->_flags & __SOFF)
			curoff = fp->_offset;
		else {
			curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
			if (curoff == (fpos_t)-1) {
				FUNLOCKFILE(fp);
				return (EOF);
			}
		}
		if (fp->_flags & __SRD) {
			curoff -= fp->_r;
			if (HASUB(fp))
				curoff -= fp->_ur;
		} else if (fp->_flags & __SWR && fp->_p != NULL)
			curoff += fp->_p - fp->_bf._base;

		offset += curoff;
		whence = SEEK_SET;
		havepos = 1;
		break;

	case SEEK_SET:
	case SEEK_END:
		curoff = 0;		/* XXX just to keep gcc quiet */
		havepos = 0;
		break;

	default:
		FUNLOCKFILE(fp);
		errno = EINVAL;
		return (EOF);
	}

	/*
	 * 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;
		target = st.st_size + offset;
	}

	if (!havepos) {
		if (fp->_flags & __SOFF)
			curoff = fp->_offset;
		else {
			curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
			if (curoff == POS_ERR)
				goto dumb;
		}
		curoff -= fp->_r;
		if (HASUB(fp))
			curoff -= fp->_ur;
	}

	/*
	 * 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 the buffer was modified, we have to
	 * skip this; see fgetln.c.)
	 */
	if ((fp->_flags & __SMOD) == 0 &&
	    target >= curoff && target < curoff + n) {
		int o = target - curoff;

		fp->_p = fp->_bf._base + o;
		fp->_r = n - o;
		if (HASUB(fp))
			FREEUB(fp);
		fp->_flags &= ~__SEOF;
		FUNLOCKFILE(fp);
		return (0);
	}

	/*
	 * 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 ((*seekfn)(fp->_cookie, curoff, SEEK_SET) == POS_ERR)
		goto dumb;
	fp->_r = 0;
 	fp->_p = fp->_bf._base;
	if (HASUB(fp))
		FREEUB(fp);
	fp->_flags &= ~__SEOF;
	n = target - curoff;
	if (n) {
		if (__srefill(fp) || fp->_r < n)
			goto dumb;
		fp->_p += n;
		fp->_r -= n;
	}
	FUNLOCKFILE(fp);
	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) ||
	    (*seekfn)(fp->_cookie, (fpos_t)offset, whence) == POS_ERR) {
		FUNLOCKFILE(fp);
		return (EOF);
	}
	/* 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;
	FUNLOCKFILE(fp);
	return (0);
}
DEF_WEAK(fseeko);

int
fseek(FILE *fp, long offset, int whence)
{
	return (fseeko(fp, offset, whence));
}
DEF_STRONG(fseek);


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: fseek.c,v 1.12 2015/08/31 02:53:57 guenther Exp $ */
2			/*-
3			* Copyright (c) 1990, 1993
4			* The Regents of the University of California. All rights reserved.
5			*
6			* This code is derived from software contributed to Berkeley by
7			* Chris Torek.
8			*
9			* Redistribution and use in source and binary forms, with or without
10			* modification, are permitted provided that the following conditions
11			* are met:
12			* 1. Redistributions of source code must retain the above copyright
13			* notice, this list of conditions and the following disclaimer.
14			* 2. Redistributions in binary form must reproduce the above copyright
15			* notice, this list of conditions and the following disclaimer in the
16			* documentation and/or other materials provided with the distribution.
17			* 3. Neither the name of the University nor the names of its contributors
18			* may be used to endorse or promote products derived from this software
19			* without specific prior written permission.
20			*
21			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24			* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31			* SUCH DAMAGE.
32			*/
33
34			#include <sys/types.h>
35			#include <sys/stat.h>
36			#include <fcntl.h>
37			#include <stdio.h>
38			#include <stdlib.h>
39			#include <errno.h>
40			#include "local.h"
41
42			#define POS_ERR (-(fpos_t)1)
43
44			/*
45			* Seek the given file to the given offset.
46			* `Whence' must be one of the three SEEK_* macros.
47			*/
48			int
49			fseeko(FILE *fp, off_t offset, int whence)
50			{
51			fpos_t (seekfn)(void , fpos_t, int);
52			fpos_t target, curoff;
53			size_t n;
54		2076	struct stat st;
55			int havepos;
56
57			/* make sure stdio is set up */
58	✗✓	1038	if (!__sdidinit)
59			__sinit();
60
61			/*
62			* Have to be able to seek.
63			*/
64	✗✓	1038	if ((seekfn = fp->_seek) == NULL) {
65			errno = ESPIPE; /* historic practice */
66			return (EOF);
67			}
68
69			/*
70			* Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
71			* After this, whence is either SEEK_SET or SEEK_END.
72			*/
73	✗✓	1038	FLOCKFILE(fp);
74	✗✗✓✗	1038	switch (whence) {
75
76			case SEEK_CUR:
77			/*
78			* In order to seek relative to the current stream offset,
79			* we have to first find the current stream offset a la
80			* ftell (see ftell for details).
81			*/
82			__sflush(fp); /* may adjust seek offset on append stream */
83			if (fp->_flags & __SOFF)
84			curoff = fp->_offset;
85			else {
86			curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
87			if (curoff == (fpos_t)-1) {
88			FUNLOCKFILE(fp);
89			return (EOF);
90			}
91			}
92			if (fp->_flags & __SRD) {
93			curoff -= fp->_r;
94			if (HASUB(fp))
95			curoff -= fp->_ur;
96			} else if (fp->_flags & __SWR && fp->_p != NULL)
97			curoff += fp->_p - fp->_bf._base;
98
99			offset += curoff;
100			whence = SEEK_SET;
101			havepos = 1;
102			break;
103
104			case SEEK_SET:
105			case SEEK_END:
106			curoff = 0; /* XXX just to keep gcc quiet */
107			havepos = 0;
108		1038	break;
109
110			default:
111			FUNLOCKFILE(fp);
112			errno = EINVAL;
113			return (EOF);
114			}
115
116			/*
117			* Can only optimise if:
118			* reading (and not reading-and-writing);
119			* not unbuffered; and
120			* this is a `regular' Unix file (and hence seekfn==__sseek).
121			* We must check __NBF first, because it is possible to have __NBF
122			* and __SOPT both set.
123			*/
124	✓✗	1038	if (fp->_bf._base == NULL)
125		1038	__smakebuf(fp);
126	✗✓	1038	if (fp->_flags & (__SWR \| __SRW \| __SNBF \| __SNPT))
127			goto dumb;
128			if ((fp->_flags & __SOPT) == 0) {
129			if (seekfn != __sseek \|\|
130			fp->_file < 0 \|\| fstat(fp->_file, &st) \|\|
131			(st.st_mode & S_IFMT) != S_IFREG) {
132			fp->_flags \|= __SNPT;
133			goto dumb;
134			}
135			fp->_blksize = st.st_blksize;
136			fp->_flags \|= __SOPT;
137			}
138
139			/*
140			* We are reading; we can try to optimise.
141			* Figure out where we are going and where we are now.
142			*/
143			if (whence == SEEK_SET)
144			target = offset;
145			else {
146			if (fstat(fp->_file, &st))
147			goto dumb;
148			target = st.st_size + offset;
149			}
150
151			if (!havepos) {
152			if (fp->_flags & __SOFF)
153			curoff = fp->_offset;
154			else {
155			curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
156			if (curoff == POS_ERR)
157			goto dumb;
158			}
159			curoff -= fp->_r;
160			if (HASUB(fp))
161			curoff -= fp->_ur;
162			}
163
164			/*
165			* Compute the number of bytes in the input buffer (pretending
166			* that any ungetc() input has been discarded). Adjust current
167			* offset backwards by this count so that it represents the
168			* file offset for the first byte in the current input buffer.
169			*/
170			if (HASUB(fp)) {
171			curoff += fp->_r; /* kill off ungetc */
172			n = fp->_up - fp->_bf._base;
173			curoff -= n;
174			n += fp->_ur;
175			} else {
176			n = fp->_p - fp->_bf._base;
177			curoff -= n;
178			n += fp->_r;
179			}
180
181			/*
182			* If the target offset is within the current buffer,
183			* simply adjust the pointers, clear EOF, undo ungetc(),
184			* and return. (If the buffer was modified, we have to
185			* skip this; see fgetln.c.)
186			*/
187			if ((fp->_flags & __SMOD) == 0 &&
188			target >= curoff && target < curoff + n) {
189			int o = target - curoff;
190
191			fp->_p = fp->_bf._base + o;
192			fp->_r = n - o;
193			if (HASUB(fp))
194			FREEUB(fp);
195			fp->_flags &= ~__SEOF;
196			FUNLOCKFILE(fp);
197			return (0);
198			}
199
200			/*
201			* The place we want to get to is not within the current buffer,
202			* but we can still be kind to the kernel copyout mechanism.
203			* By aligning the file offset to a block boundary, we can let
204			* the kernel use the VM hardware to map pages instead of
205			* copying bytes laboriously. Using a block boundary also
206			* ensures that we only read one block, rather than two.
207			*/
208			curoff = target & ~(fp->_blksize - 1);
209			if ((*seekfn)(fp->_cookie, curoff, SEEK_SET) == POS_ERR)
210			goto dumb;
211			fp->_r = 0;
212			fp->_p = fp->_bf._base;
213			if (HASUB(fp))
214			FREEUB(fp);
215			fp->_flags &= ~__SEOF;
216			n = target - curoff;
217			if (n) {
218			if (__srefill(fp) \|\| fp->_r < n)
219			goto dumb;
220			fp->_p += n;
221			fp->_r -= n;
222			}
223			FUNLOCKFILE(fp);
224			return (0);
225
226			/*
227			* We get here if we cannot optimise the seek ... just
228			* do it. Allow the seek function to change fp->_bf._base.
229			*/
230			dumb:
231	✓✗✗✓	2076	if (__sflush(fp) \|\|
232		1038	(*seekfn)(fp->_cookie, (fpos_t)offset, whence) == POS_ERR) {
233			FUNLOCKFILE(fp);
234			return (EOF);
235			}
236			/* success: clear EOF indicator and discard ungetc() data */
237	✗✓	1038	if (HASUB(fp))
238			FREEUB(fp);
239		1038	fp->_p = fp->_bf._base;
240		1038	fp->_r = 0;
241			/* fp->_w = 0; / / unnecessary (I think...) */
242		1038	fp->_flags &= ~__SEOF;
243	✗✓	1038	FUNLOCKFILE(fp);
244		1038	return (0);
245		1038	}
246			DEF_WEAK(fseeko);
247
248			int
249			fseek(FILE *fp, long offset, int whence)
250			{
251		2076	return (fseeko(fp, offset, whence));
252			}
253			DEF_STRONG(fseek);