296 lines
7.0 KiB
C
296 lines
7.0 KiB
C
/*
|
|
* softmagic - interpret variable magic from /etc/magic
|
|
*
|
|
* Copyright (c) Ian F. Darwin, 1987.
|
|
* Written by Ian F. Darwin.
|
|
*
|
|
* This software is not subject to any license of the American Telephone
|
|
* and Telegraph Company or of the Regents of the University of California.
|
|
*
|
|
* Permission is granted to anyone to use this software for any purpose on
|
|
* any computer system, and to alter it and redistribute it freely, subject
|
|
* to the following restrictions:
|
|
*
|
|
* 1. The author is not responsible for the consequences of use of this
|
|
* software, no matter how awful, even if they arise from flaws in it.
|
|
*
|
|
* 2. The origin of this software must not be misrepresented, either by
|
|
* explicit claim or by omission. Since few users ever read sources,
|
|
* credits must appear in the documentation.
|
|
*
|
|
* 3. Altered versions must be plainly marked as such, and must not be
|
|
* misrepresented as being the original software. Since few users
|
|
* ever read sources, credits must appear in the documentation.
|
|
*
|
|
* 4. This notice may not be removed or altered.
|
|
*/
|
|
|
|
#ifndef lint
|
|
static char rcsid[] = "$Id: softmagic.c,v 1.5 1993/11/03 04:04:22 mycroft Exp $";
|
|
#endif /* not lint */
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <time.h>
|
|
#include <sys/types.h>
|
|
|
|
#include "file.h"
|
|
|
|
static int match __P((unsigned char *));
|
|
static int mcheck __P((unsigned char *, struct magic *));
|
|
static void mprint __P((unsigned char *, struct magic *, unsigned long));
|
|
extern unsigned long signextend __P((struct magic *, unsigned long));
|
|
|
|
static int need_separator;
|
|
|
|
/*
|
|
* softmagic - lookup one file in database
|
|
* (already read from /etc/magic by apprentice.c).
|
|
* Passed the name and FILE * of one file to be typed.
|
|
*/
|
|
/*ARGSUSED1*/ /* nbytes passed for regularity, maybe need later */
|
|
int
|
|
softmagic(buf, nbytes)
|
|
unsigned char *buf;
|
|
int nbytes;
|
|
{
|
|
if (match(buf))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Go through the whole list, stopping if you find a match. Process all
|
|
* the continuations of that match before returning.
|
|
*
|
|
* We support multi-level continuations:
|
|
*
|
|
* At any time when processing a successful top-level match, there is a
|
|
* current continuation level; it represents the level of the last
|
|
* successfully matched continuation.
|
|
*
|
|
* Continuations above that level are skipped as, if we see one, it
|
|
* means that the continuation that controls them - i.e, the
|
|
* lower-level continuation preceding them - failed to match.
|
|
*
|
|
* Continuations below that level are processed as, if we see one,
|
|
* it means we've finished processing or skipping higher-level
|
|
* continuations under the control of a successful or unsuccessful
|
|
* lower-level continuation, and are now seeing the next lower-level
|
|
* continuation and should process it. The current continuation
|
|
* level reverts to the level of the one we're seeing.
|
|
*
|
|
* Continuations at the current level are processed as, if we see
|
|
* one, there's no lower-level continuation that may have failed.
|
|
*
|
|
* If a continuation matches, we bump the current continuation level
|
|
* so that higher-level continuations are processed.
|
|
*/
|
|
static int
|
|
match(s)
|
|
unsigned char *s;
|
|
{
|
|
int magindex = 0;
|
|
int cont_level = 0;
|
|
|
|
while (magindex < nmagic) {
|
|
/* if main entry matches, print it... */
|
|
need_separator = 0;
|
|
if (mcheck(s, &magic[magindex])) {
|
|
/* and any continuations that match */
|
|
cont_level++;
|
|
while (magic[magindex+1].cont_level != 0 &&
|
|
magindex < nmagic) {
|
|
++magindex;
|
|
if (cont_level >=
|
|
magic[magindex].cont_level) {
|
|
if (cont_level >
|
|
magic[magindex].cont_level) {
|
|
/*
|
|
* We're at the end of the
|
|
* level-"cont_level"
|
|
* continuations.
|
|
*/
|
|
cont_level =
|
|
magic[magindex].cont_level;
|
|
}
|
|
if (mcheck(s, &magic[magindex])) {
|
|
/*
|
|
* This continuation matched.
|
|
* If we see any continuations
|
|
* at a higher level,
|
|
* process them.
|
|
*/
|
|
cont_level++;
|
|
}
|
|
}
|
|
}
|
|
return 1; /* all through */
|
|
} else {
|
|
/* main entry didn't match, flush its continuation */
|
|
while (magic[magindex+1].cont_level != 0 &&
|
|
magindex < nmagic) {
|
|
++magindex;
|
|
}
|
|
}
|
|
++magindex; /* on to the next */
|
|
}
|
|
return 0; /* no match at all */
|
|
}
|
|
|
|
static void
|
|
mprint(s, m, v)
|
|
unsigned char *s;
|
|
struct magic *m;
|
|
unsigned long v;
|
|
{
|
|
register union VALUETYPE *p = (union VALUETYPE *)(s+m->offset);
|
|
char *pp, *rt;
|
|
|
|
if (m->desc[0]) {
|
|
if (need_separator && !m->nospflag)
|
|
(void) putchar(' ');
|
|
need_separator = 1;
|
|
}
|
|
|
|
switch (m->type) {
|
|
case BYTE:
|
|
case SHORT:
|
|
case BESHORT:
|
|
case LESHORT:
|
|
case LONG:
|
|
case BELONG:
|
|
case LELONG:
|
|
(void) printf(m->desc, v);
|
|
break;
|
|
case STRING:
|
|
if ((rt=strchr(p->s, '\n')) != NULL)
|
|
*rt = '\0';
|
|
(void) printf(m->desc, p->s);
|
|
if (rt)
|
|
*rt = '\n';
|
|
break;
|
|
case DATE:
|
|
case BEDATE:
|
|
case LEDATE:
|
|
pp = ctime((time_t*) &v);
|
|
if ((rt = strchr(pp, '\n')) != NULL)
|
|
*rt = '\0';
|
|
(void) printf(m->desc, pp);
|
|
if (rt)
|
|
*rt = '\n';
|
|
break;
|
|
default:
|
|
error("invalid m->type (%d) in mprint().\n", m->type);
|
|
/*NOTREACHED*/
|
|
}
|
|
}
|
|
|
|
static int
|
|
mcheck(s, m)
|
|
unsigned char *s;
|
|
struct magic *m;
|
|
{
|
|
register union VALUETYPE *p = (union VALUETYPE *)(s+m->offset);
|
|
register unsigned long l = m->value.l;
|
|
register unsigned long v;
|
|
register int matched;
|
|
|
|
if (debug) {
|
|
(void) printf("mcheck: %10.10s ", s);
|
|
mdump(m);
|
|
}
|
|
|
|
#if 0
|
|
if ( (m->value.s[0] == 'x') && (m->value.s[1] == '\0') ) {
|
|
printf("BOINK");
|
|
return 1;
|
|
}
|
|
#endif
|
|
|
|
switch (m->type) {
|
|
case BYTE:
|
|
v = p->b; break;
|
|
case SHORT:
|
|
v = p->h; break;
|
|
case LONG:
|
|
case DATE:
|
|
v = p->l; break;
|
|
case STRING:
|
|
l = 0;
|
|
/* What we want here is:
|
|
* v = strncmp(m->value.s, p->s, m->vallen);
|
|
* but ignoring any nulls. bcmp doesn't give -/+/0
|
|
* and isn't universally available anyway.
|
|
*/
|
|
v = 0;
|
|
{
|
|
register unsigned char *a = (unsigned char*)m->value.s;
|
|
register unsigned char *b = (unsigned char*)p->s;
|
|
register int len = m->vallen;
|
|
|
|
while (--len >= 0)
|
|
if ((v = *b++ - *a++) != 0)
|
|
break;
|
|
}
|
|
break;
|
|
case BESHORT:
|
|
v = (unsigned short)((p->hs[0]<<8)|(p->hs[1]));
|
|
break;
|
|
case BELONG:
|
|
case BEDATE:
|
|
v = (unsigned long)
|
|
((p->hl[0]<<24)|(p->hl[1]<<16)|(p->hl[2]<<8)|(p->hl[3]));
|
|
break;
|
|
case LESHORT:
|
|
v = (unsigned short)((p->hs[1]<<8)|(p->hs[0]));
|
|
break;
|
|
case LELONG:
|
|
case LEDATE:
|
|
v = (unsigned long)
|
|
((p->hl[3]<<24)|(p->hl[2]<<16)|(p->hl[1]<<8)|(p->hl[0]));
|
|
break;
|
|
default:
|
|
error("invalid type %d in mcheck().\n", m->type);
|
|
return -1;/*NOTREACHED*/
|
|
}
|
|
|
|
v = signextend(m, v);
|
|
|
|
if (m->flag & MASK)
|
|
v &= m->mask;
|
|
|
|
switch (m->reln) {
|
|
case 'x':
|
|
matched = 1; break;
|
|
case '!':
|
|
matched = v != l; break;
|
|
case '=':
|
|
matched = v == l; break;
|
|
case '>':
|
|
if (m->flag & UNSIGNED)
|
|
matched = v > l;
|
|
else
|
|
matched = (long)v > (long)l;
|
|
break;
|
|
case '<':
|
|
if (m->flag & UNSIGNED)
|
|
matched = v < l;
|
|
else
|
|
matched = (long)v < (long)l;
|
|
break;
|
|
case '&':
|
|
matched = (v & l) == l; break;
|
|
case '^':
|
|
matched = (v & l) != l; break;
|
|
default:
|
|
error("mcheck: can't happen: invalid relation %d.\n", m->reln);
|
|
return -1;/*NOTREACHED*/
|
|
}
|
|
|
|
if (matched)
|
|
mprint(s, m, v);
|
|
return matched;
|
|
}
|