1 /* $NetBSD: is_simh.c,v 1.1.1.1 2023/08/18 18:36:49 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2023 Christos Zoulas 5 * 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 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * Parse SIM-H tape files 31 * http://simh.trailing-edge.com/docs/simh_magtape.pdf 32 */ 33 34 #ifndef TEST 35 #include "file.h" 36 37 #ifndef lint 38 #if 0 39 FILE_RCSID("@(#)$File: is_simh.c,v 1.10 2023/07/27 19:39:55 christos Exp $") 40 #else 41 __RCSID("$NetBSD: is_simh.c,v 1.1.1.1 2023/08/18 18:36:49 christos Exp $"); 42 #endif 43 #endif 44 45 #include <string.h> 46 #include <stddef.h> 47 #include "magic.h" 48 #else 49 #include <stdint.h> 50 #include <sys/types.h> 51 #include <string.h> 52 #include <stddef.h> 53 #define CAST(a, b) (a)(b) 54 #endif 55 56 57 #ifdef DEBUG 58 #include <stdio.h> 59 #define DPRINTF(fmt, ...) printf(fmt, __VA_ARGS__) 60 #else 61 #define DPRINTF(fmt, ...) 62 #endif 63 64 /* 65 * if SIMH_TAPEMARKS == 0: 66 * check all the records and tapemarks 67 * otherwise: 68 * check only up-to the number of tapemarks specified 69 */ 70 #ifndef SIMH_TAPEMARKS 71 #define SIMH_TAPEMARKS 10 72 #endif 73 74 typedef union { 75 char s[4]; 76 uint32_t u; 77 } myword; 78 79 static myword simh_bo; 80 81 #define NEED_SWAP (simh_bo.u == CAST(uint32_t, 0x01020304)) 82 83 /* 84 * swap an int 85 */ 86 static uint32_t 87 swap4(uint32_t sv) 88 { 89 myword d, s; 90 s.u = sv; 91 d.s[0] = s.s[3]; 92 d.s[1] = s.s[2]; 93 d.s[2] = s.s[1]; 94 d.s[3] = s.s[0]; 95 return d.u; 96 } 97 98 99 static uint32_t 100 getlen(const unsigned char **uc) 101 { 102 uint32_t n; 103 memcpy(&n, *uc, sizeof(n)); 104 *uc += sizeof(n); 105 if (NEED_SWAP) 106 n = swap4(n); 107 if (n == 0xffffffff) /* check for End of Medium */ 108 return n; 109 n &= 0x00ffffff; /* keep only the record len */ 110 if (n & 1) 111 n++; 112 return n; 113 } 114 115 static int 116 simh_parse(const unsigned char *uc, const unsigned char *ue) 117 { 118 uint32_t nbytes, cbytes; 119 const unsigned char *orig_uc = uc; 120 size_t nt = 0, nr = 0; 121 122 (void)memcpy(simh_bo.s, "\01\02\03\04", 4); 123 124 while (ue - uc >= CAST(ptrdiff_t, sizeof(nbytes))) { 125 nbytes = getlen(&uc); 126 if ((nt > 0 || nr > 0) && nbytes == 0xFFFFFFFF) 127 /* EOM after at least one record or tapemark */ 128 break; 129 if (nbytes == 0) { 130 nt++; /* count tapemarks */ 131 #if SIMH_TAPEMARKS 132 if (nt == SIMH_TAPEMARKS) 133 break; 134 #endif 135 continue; 136 } 137 /* handle a data record */ 138 uc += nbytes; 139 if (ue - uc < CAST(ptrdiff_t, sizeof(nbytes))) 140 break; 141 cbytes = getlen(&uc); 142 if (nbytes != cbytes) 143 return 0; 144 nr++; 145 } 146 if (nt * sizeof(uint32_t) == CAST(size_t, uc - orig_uc)) 147 return 0; /* All examined data was tapemarks (0) */ 148 if (nr == 0) /* No records */ 149 return 0; 150 return 1; 151 } 152 153 #ifndef TEST 154 int 155 file_is_simh(struct magic_set *ms, const struct buffer *b) 156 { 157 const unsigned char *uc = CAST(const unsigned char *, b->fbuf); 158 const unsigned char *ue = uc + b->flen; 159 int mime = ms->flags & MAGIC_MIME; 160 161 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)) != 0) 162 return 0; 163 164 if (!simh_parse(uc, ue)) 165 return 0; 166 167 if (mime == MAGIC_MIME_ENCODING) 168 return 1; 169 170 if (mime) { 171 if (file_printf(ms, "application/SIMH-tape-data") == -1) 172 return -1; 173 return 1; 174 } 175 176 if (file_printf(ms, "SIMH tape data") == -1) 177 return -1; 178 179 return 1; 180 } 181 182 #else 183 184 #include <sys/types.h> 185 #include <sys/stat.h> 186 #include <stdio.h> 187 #include <fcntl.h> 188 #include <unistd.h> 189 #include <stdlib.h> 190 #include <stdint.h> 191 #include <err.h> 192 193 int 194 main(int argc, char *argv[]) 195 { 196 int fd; 197 struct stat st; 198 unsigned char *p; 199 200 if ((fd = open(argv[1], O_RDONLY)) == -1) 201 err(EXIT_FAILURE, "Can't open `%s'", argv[1]); 202 203 if (fstat(fd, &st) == -1) 204 err(EXIT_FAILURE, "Can't stat `%s'", argv[1]); 205 206 if ((p = CAST(char *, malloc(st.st_size))) == NULL) 207 err(EXIT_FAILURE, "Can't allocate %jd bytes", 208 (intmax_t)st.st_size); 209 if (read(fd, p, st.st_size) != st.st_size) 210 err(EXIT_FAILURE, "Can't read %jd bytes", 211 (intmax_t)st.st_size); 212 printf("is simh %d\n", simh_parse(p, p + st.st_size)); 213 return 0; 214 } 215 #endif 216