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 #include <sys/param.h> 33 #include <sys/mman.h> 34 #include <sys/stat.h> 35 36 #include <capsicum_helpers.h> 37 #include <err.h> 38 #include <limits.h> 39 #include <signal.h> 40 #include <stdlib.h> 41 #include <stdio.h> 42 #include <unistd.h> 43 44 #include "extern.h" 45 46 static u_char *remmap(u_char *, int, off_t); 47 static void segv_handler(int); 48 #define MMAP_CHUNK (8*1024*1024) 49 50 #define ROUNDPAGE(i) ((i) & ~pagemask) 51 52 void 53 c_regular(int fd1, const char *file1, off_t skip1, off_t len1, 54 int fd2, const char *file2, off_t skip2, off_t len2, off_t limit) 55 { 56 struct sigaction act, oact; 57 cap_rights_t rights; 58 u_char ch, *p1, *p2, *m1, *m2, *e1, *e2; 59 off_t byte, length, line; 60 off_t pagemask, off1, off2; 61 size_t pagesize; 62 int dfound; 63 64 if (skip1 > len1) 65 eofmsg(file1); 66 len1 -= skip1; 67 if (skip2 > len2) 68 eofmsg(file2); 69 len2 -= skip2; 70 71 if (sflag && len1 != len2) 72 exit(DIFF_EXIT); 73 74 pagesize = getpagesize(); 75 pagemask = (off_t)pagesize - 1; 76 off1 = ROUNDPAGE(skip1); 77 off2 = ROUNDPAGE(skip2); 78 79 length = MIN(len1, len2); 80 if (limit > 0) 81 length = MIN(length, limit); 82 83 if ((m1 = remmap(NULL, fd1, off1)) == NULL) { 84 c_special(fd1, file1, skip1, fd2, file2, skip2, limit); 85 return; 86 } 87 88 if ((m2 = remmap(NULL, fd2, off2)) == NULL) { 89 munmap(m1, MMAP_CHUNK); 90 c_special(fd1, file1, skip1, fd2, file2, skip2, limit); 91 return; 92 } 93 94 if (caph_rights_limit(fd1, cap_rights_init(&rights, CAP_MMAP_R)) < 0) 95 err(1, "unable to limit rights for %s", file1); 96 if (caph_rights_limit(fd2, cap_rights_init(&rights, CAP_MMAP_R)) < 0) 97 err(1, "unable to limit rights for %s", file2); 98 if (caph_enter() < 0) 99 err(ERR_EXIT, "unable to enter capability mode"); 100 101 sigemptyset(&act.sa_mask); 102 act.sa_flags = SA_NODEFER; 103 act.sa_handler = segv_handler; 104 if (sigaction(SIGSEGV, &act, &oact)) 105 err(ERR_EXIT, "sigaction()"); 106 107 dfound = 0; 108 e1 = m1 + MMAP_CHUNK; 109 e2 = m2 + MMAP_CHUNK; 110 p1 = m1 + (skip1 - off1); 111 p2 = m2 + (skip2 - off2); 112 113 for (byte = line = 1; length--; ++byte) { 114 #ifdef SIGINFO 115 if (info) { 116 (void)fprintf(stderr, "%s %s char %zu line %zu\n", 117 file1, file2, (size_t)byte, (size_t)line); 118 info = 0; 119 } 120 #endif 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 if (bflag) 129 (void)printf("%6lld %3o %c %3o %c\n", 130 (long long)byte, ch, ch, *p2, *p2); 131 else 132 (void)printf("%6lld %3o %3o\n", 133 (long long)byte, ch, *p2); 134 } else 135 diffmsg(file1, file2, byte, line, ch, *p2); 136 /* NOTREACHED */ 137 } 138 if (ch == '\n') 139 ++line; 140 if (++p1 == e1) { 141 off1 += MMAP_CHUNK; 142 if ((p1 = m1 = remmap(m1, fd1, off1)) == NULL) { 143 munmap(m2, MMAP_CHUNK); 144 err(ERR_EXIT, "remmap %s", file1); 145 } 146 e1 = m1 + MMAP_CHUNK; 147 } 148 if (++p2 == e2) { 149 off2 += MMAP_CHUNK; 150 if ((p2 = m2 = remmap(m2, fd2, off2)) == NULL) { 151 munmap(m1, MMAP_CHUNK); 152 err(ERR_EXIT, "remmap %s", file2); 153 } 154 e2 = m2 + MMAP_CHUNK; 155 } 156 } 157 munmap(m1, MMAP_CHUNK); 158 munmap(m2, MMAP_CHUNK); 159 160 if (sigaction(SIGSEGV, &oact, NULL)) 161 err(ERR_EXIT, "sigaction()"); 162 163 if (len1 != len2) 164 eofmsg (len1 > len2 ? file2 : file1); 165 if (dfound) 166 exit(DIFF_EXIT); 167 } 168 169 static u_char * 170 remmap(u_char *mem, int fd, off_t offset) 171 { 172 if (mem != NULL) 173 munmap(mem, MMAP_CHUNK); 174 mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset); 175 if (mem == MAP_FAILED) 176 return (NULL); 177 madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL); 178 return (mem); 179 } 180 181 static void 182 segv_handler(int sig __unused) { 183 static const char msg[] = "cmp: Input/output error (caught SIGSEGV)\n"; 184 185 write(STDERR_FILENO, msg, sizeof(msg)); 186 _exit(EXIT_FAILURE); 187 } 188