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
34static char sccsid[] = "@(#)regular.c	8.3 (Berkeley) 4/2/94";
35#endif
36#endif
37
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include <sys/param.h>
42#include <sys/mman.h>
43#include <sys/stat.h>
44
45#include <capsicum_helpers.h>
46#include <err.h>
47#include <limits.h>
48#include <signal.h>
49#include <stdlib.h>
50#include <stdio.h>
51#include <unistd.h>
52
53#include "extern.h"
54
55static u_char *remmap(u_char *, int, off_t);
56static void segv_handler(int);
57#define MMAP_CHUNK (8*1024*1024)
58
59#define ROUNDPAGE(i) ((i) & ~pagemask)
60
61void
62c_regular(int fd1, const char *file1, off_t skip1, off_t len1,
63    int fd2, const char *file2, off_t skip2, off_t len2)
64{
65	struct sigaction act, oact;
66	cap_rights_t rights;
67	u_char ch, *p1, *p2, *m1, *m2, *e1, *e2;
68	off_t byte, length, line;
69	off_t pagemask, off1, off2;
70	size_t pagesize;
71	int dfound;
72
73	if (skip1 > len1)
74		eofmsg(file1);
75	len1 -= skip1;
76	if (skip2 > len2)
77		eofmsg(file2);
78	len2 -= skip2;
79
80	if (sflag && len1 != len2)
81		exit(DIFF_EXIT);
82
83	pagesize = getpagesize();
84	pagemask = (off_t)pagesize - 1;
85	off1 = ROUNDPAGE(skip1);
86	off2 = ROUNDPAGE(skip2);
87
88	length = MIN(len1, len2);
89
90	if ((m1 = remmap(NULL, fd1, off1)) == NULL) {
91		c_special(fd1, file1, skip1, fd2, file2, skip2);
92		return;
93	}
94
95	if ((m2 = remmap(NULL, fd2, off2)) == NULL) {
96		munmap(m1, MMAP_CHUNK);
97		c_special(fd1, file1, skip1, fd2, file2, skip2);
98		return;
99	}
100
101	if (caph_rights_limit(fd1, cap_rights_init(&rights, CAP_MMAP_R)) < 0)
102		err(1, "unable to limit rights for %s", file1);
103	if (caph_rights_limit(fd2, cap_rights_init(&rights, CAP_MMAP_R)) < 0)
104		err(1, "unable to limit rights for %s", file2);
105	if (caph_enter() < 0)
106		err(ERR_EXIT, "unable to enter capability mode");
107
108	sigemptyset(&act.sa_mask);
109	act.sa_flags = SA_NODEFER;
110	act.sa_handler = segv_handler;
111	if (sigaction(SIGSEGV, &act, &oact))
112		err(ERR_EXIT, "sigaction()");
113
114	dfound = 0;
115	e1 = m1 + MMAP_CHUNK;
116	e2 = m2 + MMAP_CHUNK;
117	p1 = m1 + (skip1 - off1);
118	p2 = m2 + (skip2 - off2);
119
120	for (byte = line = 1; length--; ++byte) {
121		if ((ch = *p1) != *p2) {
122			if (xflag) {
123				dfound = 1;
124				(void)printf("%08llx %02x %02x\n",
125				    (long long)byte - 1, ch, *p2);
126			} else if (lflag) {
127				dfound = 1;
128				(void)printf("%6lld %3o %3o\n",
129				    (long long)byte, ch, *p2);
130			} else
131				diffmsg(file1, file2, byte, line);
132				/* NOTREACHED */
133		}
134		if (ch == '\n')
135			++line;
136		if (++p1 == e1) {
137			off1 += MMAP_CHUNK;
138			if ((p1 = m1 = remmap(m1, fd1, off1)) == NULL) {
139				munmap(m2, MMAP_CHUNK);
140				err(ERR_EXIT, "remmap %s", file1);
141			}
142			e1 = m1 + MMAP_CHUNK;
143		}
144		if (++p2 == e2) {
145			off2 += MMAP_CHUNK;
146			if ((p2 = m2 = remmap(m2, fd2, off2)) == NULL) {
147				munmap(m1, MMAP_CHUNK);
148				err(ERR_EXIT, "remmap %s", file2);
149			}
150			e2 = m2 + MMAP_CHUNK;
151		}
152	}
153	munmap(m1, MMAP_CHUNK);
154	munmap(m2, MMAP_CHUNK);
155
156	if (sigaction(SIGSEGV, &oact, NULL))
157		err(ERR_EXIT, "sigaction()");
158
159	if (len1 != len2)
160		eofmsg (len1 > len2 ? file2 : file1);
161	if (dfound)
162		exit(DIFF_EXIT);
163}
164
165static u_char *
166remmap(u_char *mem, int fd, off_t offset)
167{
168	if (mem != NULL)
169		munmap(mem, MMAP_CHUNK);
170	mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset);
171	if (mem == MAP_FAILED)
172		return (NULL);
173	madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL);
174	return (mem);
175}
176
177static void
178segv_handler(int sig __unused) {
179	static const char msg[] = "cmp: Input/output error (caught SIGSEGV)\n";
180
181	write(STDERR_FILENO, msg, sizeof(msg));
182	_exit(EXIT_FAILURE);
183}
184