xref: /freebsd/usr.bin/tail/misc.c (revision 7899f917b1c0ea178f1d2be0cfb452086d079d23)
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 
36 
37 #include <sys/types.h>
38 #include <sys/stat.h>
39 #include <sys/mman.h>
40 
41 #include <err.h>
42 #include <errno.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47 
48 #include <libcasper.h>
49 #include <casper/cap_fileargs.h>
50 
51 #include "extern.h"
52 
53 void
54 ierr(const char *fname)
55 {
56 	warn("%s", fname);
57 	rval = 1;
58 }
59 
60 void
61 oerr(void)
62 {
63 	err(1, "stdout");
64 }
65 
66 /*
67  * Print `len' bytes from the file associated with `mip', starting at
68  * absolute file offset `startoff'. May move map window.
69  */
70 int
71 mapprint(struct mapinfo *mip, off_t startoff, off_t len)
72 {
73 	int n;
74 
75 	while (len > 0) {
76 		if (startoff < mip->mapoff || startoff >= mip->mapoff +
77 		    (off_t)mip->maplen) {
78 			if (maparound(mip, startoff) != 0)
79 				return (1);
80 		}
81 		n = (mip->mapoff + mip->maplen) - startoff;
82 		if (n > len)
83 			n = len;
84 		WR(mip->start + (startoff - mip->mapoff), n);
85 		startoff += n;
86 		len -= n;
87 	}
88 	return (0);
89 }
90 
91 /*
92  * Move the map window so that it contains the byte at absolute file
93  * offset `offset'. The start of the map window will be TAILMAPLEN
94  * aligned.
95  */
96 int
97 maparound(struct mapinfo *mip, off_t offset)
98 {
99 
100 	if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
101 		return (1);
102 
103 	mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
104 	mip->maplen = TAILMAPLEN;
105 	if ((off_t)mip->maplen > mip->maxoff - mip->mapoff)
106 		mip->maplen = mip->maxoff - mip->mapoff;
107 	if (mip->maplen <= 0)
108 		abort();
109 	if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
110 	     mip->fd, mip->mapoff)) == MAP_FAILED)
111 		return (1);
112 
113 	return (0);
114 }
115 
116 /*
117  * Print the file name without stdio buffering.
118  */
119 void
120 printfn(const char *fn, int print_nl)
121 {
122 
123 	if (print_nl)
124 		WR("\n", 1);
125 	WR("==> ", 4);
126 	WR(fn, strlen(fn));
127 	WR(" <==\n", 5);
128 }
129