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 <stdbool.h> 41 #include <stdlib.h> 42 #include <stdio.h> 43 #include <unistd.h> 44 45 #include "extern.h" 46 47 static u_char *remmap(u_char *, int, off_t); 48 static void segv_handler(int); 49 #define MMAP_CHUNK (8*1024*1024) 50 51 #define ROUNDPAGE(i) ((i) & ~pagemask) 52 53 int 54 c_regular(int fd1, const char *file1, off_t skip1, off_t len1, 55 int fd2, const char *file2, off_t skip2, off_t len2, off_t limit) 56 { 57 struct sigaction act, oact; 58 cap_rights_t rights; 59 u_char ch, *p1, *p2, *m1, *m2, *e1, *e2; 60 off_t byte, length, line; 61 off_t pagemask, off1, off2; 62 size_t pagesize; 63 int dfound; 64 65 if (skip1 > len1) { 66 eofmsg(file1); 67 return (DIFF_EXIT); 68 } 69 len1 -= skip1; 70 if (skip2 > len2) { 71 eofmsg(file2); 72 return (DIFF_EXIT); 73 } 74 len2 -= skip2; 75 76 if (sflag && len1 != len2) 77 return (DIFF_EXIT); 78 79 pagesize = getpagesize(); 80 pagemask = (off_t)pagesize - 1; 81 off1 = ROUNDPAGE(skip1); 82 off2 = ROUNDPAGE(skip2); 83 84 length = MIN(len1, len2); 85 if (limit > 0) 86 length = MIN(length, limit); 87 88 if ((m1 = remmap(NULL, fd1, off1)) == NULL) { 89 return (c_special(fd1, file1, skip1, fd2, file2, skip2, limit)); 90 } 91 92 if ((m2 = remmap(NULL, fd2, off2)) == NULL) { 93 munmap(m1, MMAP_CHUNK); 94 return (c_special(fd1, file1, skip1, fd2, file2, skip2, limit)); 95 } 96 97 if (caph_rights_limit(fd1, cap_rights_init(&rights, CAP_MMAP_R)) < 0) 98 err(1, "unable to limit rights for %s", file1); 99 if (caph_rights_limit(fd2, cap_rights_init(&rights, CAP_MMAP_R)) < 0) 100 err(1, "unable to limit rights for %s", file2); 101 if (caph_enter() < 0) 102 err(ERR_EXIT, "unable to enter capability mode"); 103 104 sigemptyset(&act.sa_mask); 105 act.sa_flags = SA_NODEFER; 106 act.sa_handler = segv_handler; 107 if (sigaction(SIGSEGV, &act, &oact)) 108 err(ERR_EXIT, "sigaction()"); 109 110 dfound = 0; 111 e1 = m1 + MMAP_CHUNK; 112 e2 = m2 + MMAP_CHUNK; 113 p1 = m1 + (skip1 - off1); 114 p2 = m2 + (skip2 - off2); 115 116 for (byte = line = 1; length--; ++byte) { 117 #ifdef SIGINFO 118 if (info) { 119 (void)fprintf(stderr, "%s %s char %zu line %zu\n", 120 file1, file2, (size_t)byte, (size_t)line); 121 info = 0; 122 } 123 #endif 124 if ((ch = *p1) != *p2) { 125 dfound = 1; 126 if (xflag) { 127 (void)printf("%08llx %02x %02x\n", 128 (long long)byte - 1, ch, *p2); 129 } else if (lflag) { 130 if (bflag) 131 (void)printf("%6lld %3o %c %3o %c\n", 132 (long long)byte, ch, ch, *p2, *p2); 133 else 134 (void)printf("%6lld %3o %3o\n", 135 (long long)byte, ch, *p2); 136 } else { 137 diffmsg(file1, file2, byte, line, ch, *p2); 138 return (DIFF_EXIT); 139 } 140 } 141 if (ch == '\n') 142 ++line; 143 if (++p1 == e1) { 144 off1 += MMAP_CHUNK; 145 if ((p1 = m1 = remmap(m1, fd1, off1)) == NULL) { 146 munmap(m2, MMAP_CHUNK); 147 err(ERR_EXIT, "remmap %s", file1); 148 } 149 e1 = m1 + MMAP_CHUNK; 150 } 151 if (++p2 == e2) { 152 off2 += MMAP_CHUNK; 153 if ((p2 = m2 = remmap(m2, fd2, off2)) == NULL) { 154 munmap(m1, MMAP_CHUNK); 155 err(ERR_EXIT, "remmap %s", file2); 156 } 157 e2 = m2 + MMAP_CHUNK; 158 } 159 } 160 munmap(m1, MMAP_CHUNK); 161 munmap(m2, MMAP_CHUNK); 162 163 if (sigaction(SIGSEGV, &oact, NULL)) 164 err(ERR_EXIT, "sigaction()"); 165 166 if (len1 != len2) { 167 eofmsg(len1 > len2 ? file2 : file1); 168 return (DIFF_EXIT); 169 } 170 return (dfound ? DIFF_EXIT : 0); 171 } 172 173 static u_char * 174 remmap(u_char *mem, int fd, off_t offset) 175 { 176 if (mem != NULL) 177 munmap(mem, MMAP_CHUNK); 178 mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset); 179 if (mem == MAP_FAILED) 180 return (NULL); 181 madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL); 182 return (mem); 183 } 184 185 static void 186 segv_handler(int sig __unused) { 187 static const char msg[] = "cmp: Input/output error (caught SIGSEGV)\n"; 188 189 write(STDERR_FILENO, msg, sizeof(msg)); 190 _exit(EXIT_FAILURE); 191 } 192