1 /*-
2 * Copyright (c) 2023 Christos Zoulas
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
15 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
16 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
18 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
19 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
20 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
21 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
22 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
23 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
24 * POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 /*
28 * Parse SIM-H tape files
29 * http://simh.trailing-edge.com/docs/simh_magtape.pdf
30 */
31
32 #ifndef TEST
33 #include "file.h"
34
35 #ifndef lint
36 FILE_RCSID("@(#)$File: is_simh.c,v 1.10 2023/07/27 19:39:55 christos Exp $")
37 #endif
38
39 #include <string.h>
40 #include <stddef.h>
41 #include "magic.h"
42 #else
43 #include <stdint.h>
44 #include <sys/types.h>
45 #include <string.h>
46 #include <stddef.h>
47 #define CAST(a, b) (a)(b)
48 #endif
49
50
51 #ifdef DEBUG
52 #include <stdio.h>
53 #define DPRINTF(fmt, ...) printf(fmt, __VA_ARGS__)
54 #else
55 #define DPRINTF(fmt, ...)
56 #endif
57
58 /*
59 * if SIMH_TAPEMARKS == 0:
60 * check all the records and tapemarks
61 * otherwise:
62 * check only up-to the number of tapemarks specified
63 */
64 #ifndef SIMH_TAPEMARKS
65 #define SIMH_TAPEMARKS 10
66 #endif
67
68 typedef union {
69 char s[4];
70 uint32_t u;
71 } myword;
72
73 static myword simh_bo;
74
75 #define NEED_SWAP (simh_bo.u == CAST(uint32_t, 0x01020304))
76
77 /*
78 * swap an int
79 */
80 static uint32_t
swap4(uint32_t sv)81 swap4(uint32_t sv)
82 {
83 myword d, s;
84 s.u = sv;
85 d.s[0] = s.s[3];
86 d.s[1] = s.s[2];
87 d.s[2] = s.s[1];
88 d.s[3] = s.s[0];
89 return d.u;
90 }
91
92
93 static uint32_t
getlen(const unsigned char ** uc)94 getlen(const unsigned char **uc)
95 {
96 uint32_t n;
97 memcpy(&n, *uc, sizeof(n));
98 *uc += sizeof(n);
99 if (NEED_SWAP)
100 n = swap4(n);
101 if (n == 0xffffffff) /* check for End of Medium */
102 return n;
103 n &= 0x00ffffff; /* keep only the record len */
104 if (n & 1)
105 n++;
106 return n;
107 }
108
109 static int
simh_parse(const unsigned char * uc,const unsigned char * ue)110 simh_parse(const unsigned char *uc, const unsigned char *ue)
111 {
112 uint32_t nbytes, cbytes;
113 const unsigned char *orig_uc = uc;
114 size_t nt = 0, nr = 0;
115
116 (void)memcpy(simh_bo.s, "\01\02\03\04", 4);
117
118 while (ue - uc >= CAST(ptrdiff_t, sizeof(nbytes))) {
119 nbytes = getlen(&uc);
120 if ((nt > 0 || nr > 0) && nbytes == 0xFFFFFFFF)
121 /* EOM after at least one record or tapemark */
122 break;
123 if (nbytes == 0) {
124 nt++; /* count tapemarks */
125 #if SIMH_TAPEMARKS
126 if (nt == SIMH_TAPEMARKS)
127 break;
128 #endif
129 continue;
130 }
131 /* handle a data record */
132 uc += nbytes;
133 if (ue - uc < CAST(ptrdiff_t, sizeof(nbytes)))
134 break;
135 cbytes = getlen(&uc);
136 if (nbytes != cbytes)
137 return 0;
138 nr++;
139 }
140 if (nt * sizeof(uint32_t) == CAST(size_t, uc - orig_uc))
141 return 0; /* All examined data was tapemarks (0) */
142 if (nr == 0) /* No records */
143 return 0;
144 return 1;
145 }
146
147 #ifndef TEST
148 int
file_is_simh(struct magic_set * ms,const struct buffer * b)149 file_is_simh(struct magic_set *ms, const struct buffer *b)
150 {
151 const unsigned char *uc = CAST(const unsigned char *, b->fbuf);
152 const unsigned char *ue = uc + b->flen;
153 int mime = ms->flags & MAGIC_MIME;
154
155 if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)) != 0)
156 return 0;
157
158 if (!simh_parse(uc, ue))
159 return 0;
160
161 if (mime == MAGIC_MIME_ENCODING)
162 return 1;
163
164 if (mime) {
165 if (file_printf(ms, "application/SIMH-tape-data") == -1)
166 return -1;
167 return 1;
168 }
169
170 if (file_printf(ms, "SIMH tape data") == -1)
171 return -1;
172
173 return 1;
174 }
175
176 #else
177
178 #include <sys/types.h>
179 #include <sys/stat.h>
180 #include <stdio.h>
181 #include <fcntl.h>
182 #include <unistd.h>
183 #include <stdlib.h>
184 #include <stdint.h>
185 #include <err.h>
186
187 int
main(int argc,char * argv[])188 main(int argc, char *argv[])
189 {
190 int fd;
191 struct stat st;
192 unsigned char *p;
193
194 if ((fd = open(argv[1], O_RDONLY)) == -1)
195 err(EXIT_FAILURE, "Can't open `%s'", argv[1]);
196
197 if (fstat(fd, &st) == -1)
198 err(EXIT_FAILURE, "Can't stat `%s'", argv[1]);
199
200 if ((p = CAST(char *, malloc(st.st_size))) == NULL)
201 err(EXIT_FAILURE, "Can't allocate %jd bytes",
202 (intmax_t)st.st_size);
203 if (read(fd, p, st.st_size) != st.st_size)
204 err(EXIT_FAILURE, "Can't read %jd bytes",
205 (intmax_t)st.st_size);
206 printf("is simh %d\n", simh_parse(p, p + st.st_size));
207 return 0;
208 }
209 #endif
210
