misc.c revision 87712 
1/*-
2 * Copyright (c) 1991, 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 * Edward Sze-Tyan Wang.
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
37#include <sys/cdefs.h>
38
39__FBSDID("$FreeBSD: head/usr.bin/tail/misc.c 87712 2001-12-12 00:01:16Z markm $");
40
41#ifndef lint
42static const char sccsid[] = "@(#)misc.c	8.1 (Berkeley) 6/6/93";
43#endif
44
45#include <sys/types.h>
46#include <sys/stat.h>
47#include <sys/mman.h>
48
49#include <err.h>
50#include <errno.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54#include <unistd.h>
55
56#include "extern.h"
57
58void
59ierr()
60{
61	warn("%s", fname);
62	rval = 1;
63}
64
65void
66oerr()
67{
68	err(1, "stdout");
69}
70
71/*
72 * Print `len' bytes from the file associated with `mip', starting at
73 * absolute file offset `startoff'. May move map window.
74 */
75int
76mapprint(mip, startoff, len)
77	struct mapinfo *mip;
78	off_t startoff, len;
79{
80	int n;
81
82	while (len > 0) {
83		if (startoff < mip->mapoff || startoff >= mip->mapoff +
84		    mip->maplen) {
85			if (maparound(mip, startoff) != 0)
86				return (1);
87		}
88		n = (mip->mapoff + mip->maplen) - startoff;
89		if (n > len)
90			n = len;
91		WR(mip->start + (startoff - mip->mapoff), n);
92		startoff += n;
93		len -= n;
94	}
95	return (0);
96}
97
98/*
99 * Move the map window so that it contains the byte at absolute file
100 * offset `offset'. The start of the map window will be TAILMAPLEN
101 * aligned.
102 */
103int
104maparound(mip, offset)
105	struct mapinfo *mip;
106	off_t offset;
107{
108
109	if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
110		return (1);
111
112	mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
113	mip->maplen = TAILMAPLEN;
114	if (mip->maplen > mip->maxoff - mip->mapoff)
115		mip->maplen = mip->maxoff - mip->mapoff;
116	if (mip->maplen <= 0)
117		abort();
118	if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
119	     mip->fd, mip->mapoff)) == MAP_FAILED)
120		return (1);
121
122	return (0);
123}
124