xref: /freebsd/usr.bin/tail/misc.c (revision 1669d8afc64812c8d2d1d147ae1fd42ff441e1b1)
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("$FreeBSD$");
40 
41 #ifndef lint
42 static 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 
58 void
59 ierr()
60 {
61 	warn("%s", fname);
62 	rval = 1;
63 }
64 
65 void
66 oerr()
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  */
75 int
76 mapprint(struct mapinfo *mip, off_t startoff, off_t len)
77 {
78 	int n;
79 
80 	while (len > 0) {
81 		if (startoff < mip->mapoff || startoff >= mip->mapoff +
82 		    (off_t)mip->maplen) {
83 			if (maparound(mip, startoff) != 0)
84 				return (1);
85 		}
86 		n = (mip->mapoff + mip->maplen) - startoff;
87 		if (n > len)
88 			n = len;
89 		WR(mip->start + (startoff - mip->mapoff), n);
90 		startoff += n;
91 		len -= n;
92 	}
93 	return (0);
94 }
95 
96 /*
97  * Move the map window so that it contains the byte at absolute file
98  * offset `offset'. The start of the map window will be TAILMAPLEN
99  * aligned.
100  */
101 int
102 maparound(struct mapinfo *mip, off_t offset)
103 {
104 
105 	if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
106 		return (1);
107 
108 	mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
109 	mip->maplen = TAILMAPLEN;
110 	if ((off_t)mip->maplen > mip->maxoff - mip->mapoff)
111 		mip->maplen = mip->maxoff - mip->mapoff;
112 	if (mip->maplen <= 0)
113 		abort();
114 	if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
115 	     mip->fd, mip->mapoff)) == MAP_FAILED)
116 		return (1);
117 
118 	return (0);
119 }
120