xref: /freebsd/usr.bin/tail/misc.c (revision 6829dae12bb055451fa467da4589c43bd03b1e64)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Edward Sze-Tyan Wang.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include <sys/cdefs.h>
36 
37 __FBSDID("$FreeBSD$");
38 
39 #ifndef lint
40 static const char sccsid[] = "@(#)misc.c	8.1 (Berkeley) 6/6/93";
41 #endif
42 
43 #include <sys/types.h>
44 #include <sys/stat.h>
45 #include <sys/mman.h>
46 
47 #include <err.h>
48 #include <errno.h>
49 #include <stdio.h>
50 #include <stdlib.h>
51 #include <string.h>
52 #include <unistd.h>
53 
54 #include "extern.h"
55 
56 void
57 ierr(const char *fname)
58 {
59 	warn("%s", fname);
60 	rval = 1;
61 }
62 
63 void
64 oerr(void)
65 {
66 	err(1, "stdout");
67 }
68 
69 /*
70  * Print `len' bytes from the file associated with `mip', starting at
71  * absolute file offset `startoff'. May move map window.
72  */
73 int
74 mapprint(struct mapinfo *mip, off_t startoff, off_t len)
75 {
76 	int n;
77 
78 	while (len > 0) {
79 		if (startoff < mip->mapoff || startoff >= mip->mapoff +
80 		    (off_t)mip->maplen) {
81 			if (maparound(mip, startoff) != 0)
82 				return (1);
83 		}
84 		n = (mip->mapoff + mip->maplen) - startoff;
85 		if (n > len)
86 			n = len;
87 		WR(mip->start + (startoff - mip->mapoff), n);
88 		startoff += n;
89 		len -= n;
90 	}
91 	return (0);
92 }
93 
94 /*
95  * Move the map window so that it contains the byte at absolute file
96  * offset `offset'. The start of the map window will be TAILMAPLEN
97  * aligned.
98  */
99 int
100 maparound(struct mapinfo *mip, off_t offset)
101 {
102 
103 	if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
104 		return (1);
105 
106 	mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
107 	mip->maplen = TAILMAPLEN;
108 	if ((off_t)mip->maplen > mip->maxoff - mip->mapoff)
109 		mip->maplen = mip->maxoff - mip->mapoff;
110 	if (mip->maplen <= 0)
111 		abort();
112 	if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
113 	     mip->fd, mip->mapoff)) == MAP_FAILED)
114 		return (1);
115 
116 	return (0);
117 }
118 
119 /*
120  * Print the file name without stdio buffering.
121  */
122 void
123 printfn(const char *fn, int print_nl)
124 {
125 
126 	if (print_nl)
127 		WR("\n", 1);
128 	WR("==> ", 4);
129 	WR(fn, strlen(fn));
130 	WR(" <==\n", 5);
131 }
132