| 1 | /* |
| 2 | * softmagic - interpret variable magic from /etc/magic |
| 3 | * |
| 4 | * Copyright (c) Ian F. Darwin, 1987. |
| 5 | * Written by Ian F. Darwin. |
| 6 | * |
| 7 | * This software is not subject to any license of the American Telephone |
| 8 | * and Telegraph Company or of the Regents of the University of California. |
| 9 | * |
| 10 | * Permission is granted to anyone to use this software for any purpose on |
| 11 | * any computer system, and to alter it and redistribute it freely, subject |
| 12 | * to the following restrictions: |
| 13 | * |
| 14 | * 1. The author is not responsible for the consequences of use of this |
| 15 | * software, no matter how awful, even if they arise from flaws in it. |
| 16 | * |
| 17 | * 2. The origin of this software must not be misrepresented, either by |
| 18 | * explicit claim or by omission. Since few users ever read sources, |
| 19 | * credits must appear in the documentation. |
| 20 | * |
| 21 | * 3. Altered versions must be plainly marked as such, and must not be |
| 22 | * misrepresented as being the original software. Since few users |
| 23 | * ever read sources, credits must appear in the documentation. |
| 24 | * |
| 25 | * 4. This notice may not be removed or altered. |
| 26 | */ |
| 27 | |
| 28 | #include <stdio.h> |
| 29 | #include "file.h" |
| 30 | |
| 31 | #ifndef lint |
| 32 | static char *moduleid = |
| 33 | "@(#)$Header: softmagic.c,v 1.7 87/11/06 11:25:31 ian Exp $"; |
| 34 | #endif /* lint */ |
| 35 | |
| 36 | extern char *progname; |
| 37 | extern char *magicfile; /* name of current /etc/magic or clone */ |
| 38 | extern int debug, nmagic; |
| 39 | extern FILE *efopen(); |
| 40 | extern struct magic magic[]; |
| 41 | static int magindex; |
| 42 | |
| 43 | /* |
| 44 | * softmagic - lookup one file in database |
| 45 | * (already read from /etc/magic by apprentice.c). |
| 46 | * Passed the name and FILE * of one file to be typed. |
| 47 | */ |
| 48 | softmagic(buf) |
| 49 | char *buf; |
| 50 | { |
| 51 | magindex = 0; |
| 52 | if (match(buf)) |
| 53 | return 1; |
| 54 | |
| 55 | return 0; |
| 56 | } |
| 57 | |
| 58 | /* |
| 59 | * go through the whole list, stopping if you find a match. |
| 60 | * Be sure to process every continuation of this match. |
| 61 | */ |
| 62 | match(s) |
| 63 | char *s; |
| 64 | { |
| 65 | while (magindex < nmagic) { |
| 66 | /* if main entry matches, print it... */ |
| 67 | if (mcheck(s, &magic[magindex])) { |
| 68 | mprint(&magic[magindex],s); |
| 69 | /* and any continuations that match */ |
| 70 | while (magic[magindex+1].contflag && |
| 71 | magindex < nmagic) { |
| 72 | ++magindex; |
| 73 | if (mcheck(s, &magic[magindex])){ |
| 74 | (void) putchar(' '); |
| 75 | mprint(&magic[magindex],s); |
| 76 | } |
| 77 | } |
| 78 | return 1; /* all through */ |
| 79 | } else { |
| 80 | /* main entry didn't match, flush its continuations */ |
| 81 | while (magic[magindex+1].contflag && |
| 82 | magindex < nmagic) { |
| 83 | ++magindex; |
| 84 | } |
| 85 | } |
| 86 | ++magindex; /* on to the next */ |
| 87 | } |
| 88 | return 0; /* no match at all */ |
| 89 | } |
| 90 | |
| 91 | |
| 92 | mprint(m,s) |
| 93 | struct magic *m; |
| 94 | char *s; |
| 95 | { |
| 96 | register union VALUETYPE *p = (union VALUETYPE *)(s+m->offset); |
| 97 | char *pp, *strchr(); |
| 98 | |
| 99 | switch (m->type) { |
| 100 | case BYTE: |
| 101 | (void) printf(m->desc, p->b); |
| 102 | break; |
| 103 | case SHORT: |
| 104 | (void) printf(m->desc, p->h); |
| 105 | break; |
| 106 | case LONG: |
| 107 | (void) printf(m->desc, p->l); |
| 108 | break; |
| 109 | case STRING: |
| 110 | if ((pp=strchr(p->s, '\n')) != NULL) |
| 111 | *pp = '\0'; |
| 112 | (void) printf(m->desc, p->s); |
| 113 | break; |
| 114 | default: |
| 115 | warning("invalid m->type (%d) in mprint()", m->type); |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | int |
| 120 | mcheck(s, m) |
| 121 | char *s; |
| 122 | struct magic *m; |
| 123 | { |
| 124 | register union VALUETYPE *p = (union VALUETYPE *)(s+m->offset); |
| 125 | register long l = m->value.l; |
| 126 | register long v; |
| 127 | |
| 128 | if (debug) { |
| 129 | (void) printf("mcheck: %10.10s ", s); |
| 130 | mdump(m); |
| 131 | } |
| 132 | switch (m->type) { |
| 133 | case BYTE: |
| 134 | v = p->b; break; |
| 135 | case SHORT: |
| 136 | v = p->h; break; |
| 137 | case LONG: |
| 138 | v = p->l; break; |
| 139 | case STRING: |
| 140 | l = 0; |
| 141 | /* What we want here is: |
| 142 | * v = strncmp(m->value.s, p->s, m->vallen); |
| 143 | * but ignoring any nulls. bcmp doesn't give -/+/0 |
| 144 | * and isn't universally available anyway. |
| 145 | */ |
| 146 | { |
| 147 | register unsigned char *a = (unsigned char*)m->value.s; |
| 148 | register unsigned char *b = (unsigned char*)p->s; |
| 149 | register int len = m->vallen; |
| 150 | |
| 151 | while (--len >= 0) |
| 152 | if ((v = *b++ - *a++) != 0) |
| 153 | break; |
| 154 | } |
| 155 | break; |
| 156 | default: |
| 157 | warning("invalid type %d in mcheck()", m->type); |
| 158 | return 0; |
| 159 | } |
| 160 | |
| 161 | switch (m->reln) { |
| 162 | case '=': |
| 163 | return v == l; |
| 164 | case '>': |
| 165 | return v > l; |
| 166 | case '<': |
| 167 | return v < l; |
| 168 | case '&': |
| 169 | return v & l; |
| 170 | default: |
| 171 | warning("mcheck: can't happen: invalid relation %d", m->reln); |
| 172 | return 0; |
| 173 | } |
| 174 | } |