1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #if 0
33 #ifndef lint
34 static char sccsid[] = "@(#)regular.c 8.3 (Berkeley) 4/2/94";
35 #endif
36 #endif
37
38 #include <sys/cdefs.h>
39 #include <sys/param.h>
40 #include <sys/mman.h>
41 #include <sys/stat.h>
42
43 #include <capsicum_helpers.h>
44 #include <err.h>
45 #include <limits.h>
46 #include <signal.h>
47 #include <stdbool.h>
48 #include <stdlib.h>
49 #include <stdio.h>
50 #include <unistd.h>
51
52 #include "extern.h"
53
54 static u_char *remmap(u_char *, int, off_t);
55 static void segv_handler(int);
56 #define MMAP_CHUNK (8*1024*1024)
57
58 #define ROUNDPAGE(i) ((i) & ~pagemask)
59
60 int
c_regular(int fd1,const char * file1,off_t skip1,off_t len1,int fd2,const char * file2,off_t skip2,off_t len2,off_t limit)61 c_regular(int fd1, const char *file1, off_t skip1, off_t len1,
62 int fd2, const char *file2, off_t skip2, off_t len2, off_t limit)
63 {
64 struct sigaction act, oact;
65 cap_rights_t rights;
66 u_char ch, *p1, *p2, *m1, *m2, *e1, *e2;
67 off_t byte, length, line;
68 off_t pagemask, off1, off2;
69 size_t pagesize;
70 int dfound;
71
72 if (skip1 > len1) {
73 eofmsg(file1);
74 return (DIFF_EXIT);
75 }
76 len1 -= skip1;
77 if (skip2 > len2) {
78 eofmsg(file2);
79 return (DIFF_EXIT);
80 }
81 len2 -= skip2;
82
83 if (sflag && len1 != len2)
84 return (DIFF_EXIT);
85
86 pagesize = getpagesize();
87 pagemask = (off_t)pagesize - 1;
88 off1 = ROUNDPAGE(skip1);
89 off2 = ROUNDPAGE(skip2);
90
91 length = MIN(len1, len2);
92 if (limit > 0)
93 length = MIN(length, limit);
94
95 if ((m1 = remmap(NULL, fd1, off1)) == NULL) {
96 return (c_special(fd1, file1, skip1, fd2, file2, skip2, limit));
97 }
98
99 if ((m2 = remmap(NULL, fd2, off2)) == NULL) {
100 munmap(m1, MMAP_CHUNK);
101 return (c_special(fd1, file1, skip1, fd2, file2, skip2, limit));
102 }
103
104 if (caph_rights_limit(fd1, cap_rights_init(&rights, CAP_MMAP_R)) < 0)
105 err(1, "unable to limit rights for %s", file1);
106 if (caph_rights_limit(fd2, cap_rights_init(&rights, CAP_MMAP_R)) < 0)
107 err(1, "unable to limit rights for %s", file2);
108 if (caph_enter() < 0)
109 err(ERR_EXIT, "unable to enter capability mode");
110
111 sigemptyset(&act.sa_mask);
112 act.sa_flags = SA_NODEFER;
113 act.sa_handler = segv_handler;
114 if (sigaction(SIGSEGV, &act, &oact))
115 err(ERR_EXIT, "sigaction()");
116
117 dfound = 0;
118 e1 = m1 + MMAP_CHUNK;
119 e2 = m2 + MMAP_CHUNK;
120 p1 = m1 + (skip1 - off1);
121 p2 = m2 + (skip2 - off2);
122
123 for (byte = line = 1; length--; ++byte) {
124 #ifdef SIGINFO
125 if (info) {
126 (void)fprintf(stderr, "%s %s char %zu line %zu\n",
127 file1, file2, (size_t)byte, (size_t)line);
128 info = 0;
129 }
130 #endif
131 if ((ch = *p1) != *p2) {
132 dfound = 1;
133 if (xflag) {
134 (void)printf("%08llx %02x %02x\n",
135 (long long)byte - 1, ch, *p2);
136 } else if (lflag) {
137 if (bflag)
138 (void)printf("%6lld %3o %c %3o %c\n",
139 (long long)byte, ch, ch, *p2, *p2);
140 else
141 (void)printf("%6lld %3o %3o\n",
142 (long long)byte, ch, *p2);
143 } else {
144 diffmsg(file1, file2, byte, line, ch, *p2);
145 return (DIFF_EXIT);
146 }
147 }
148 if (ch == '\n')
149 ++line;
150 if (++p1 == e1) {
151 off1 += MMAP_CHUNK;
152 if ((p1 = m1 = remmap(m1, fd1, off1)) == NULL) {
153 munmap(m2, MMAP_CHUNK);
154 err(ERR_EXIT, "remmap %s", file1);
155 }
156 e1 = m1 + MMAP_CHUNK;
157 }
158 if (++p2 == e2) {
159 off2 += MMAP_CHUNK;
160 if ((p2 = m2 = remmap(m2, fd2, off2)) == NULL) {
161 munmap(m1, MMAP_CHUNK);
162 err(ERR_EXIT, "remmap %s", file2);
163 }
164 e2 = m2 + MMAP_CHUNK;
165 }
166 }
167 munmap(m1, MMAP_CHUNK);
168 munmap(m2, MMAP_CHUNK);
169
170 if (sigaction(SIGSEGV, &oact, NULL))
171 err(ERR_EXIT, "sigaction()");
172
173 if (len1 != len2) {
174 eofmsg(len1 > len2 ? file2 : file1);
175 return (DIFF_EXIT);
176 }
177 return (dfound ? DIFF_EXIT : 0);
178 }
179
180 static u_char *
remmap(u_char * mem,int fd,off_t offset)181 remmap(u_char *mem, int fd, off_t offset)
182 {
183 if (mem != NULL)
184 munmap(mem, MMAP_CHUNK);
185 mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset);
186 if (mem == MAP_FAILED)
187 return (NULL);
188 madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL);
189 return (mem);
190 }
191
192 static void
segv_handler(int sig __unused)193 segv_handler(int sig __unused) {
194 static const char msg[] = "cmp: Input/output error (caught SIGSEGV)\n";
195
196 write(STDERR_FILENO, msg, sizeof(msg));
197 _exit(EXIT_FAILURE);
198 }
199