476 lines
10 KiB
C
476 lines
10 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.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <time.h>
|
|
#include <sys/types.h>
|
|
|
|
#include "file.h"
|
|
|
|
#ifndef lint
|
|
static char *moduleid =
|
|
"@(#)$Id: softmagic.c,v 1.3 1995/05/30 06:30:09 rgrimes Exp $";
|
|
#endif /* lint */
|
|
|
|
static int match __P((unsigned char *, int));
|
|
static int mget __P((union VALUETYPE *,
|
|
unsigned char *, struct magic *, int));
|
|
static int mcheck __P((union VALUETYPE *, struct magic *));
|
|
static void mprint __P((union VALUETYPE *, struct magic *));
|
|
static void mdebug __P((long, char *, int));
|
|
static int mconvert __P((union VALUETYPE *, struct magic *));
|
|
|
|
/*
|
|
* 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, nbytes))
|
|
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, nbytes)
|
|
unsigned char *s;
|
|
int nbytes;
|
|
{
|
|
int magindex = 0;
|
|
int cont_level = 0;
|
|
int need_separator = 0;
|
|
union VALUETYPE p;
|
|
|
|
for (magindex = 0; magindex < nmagic; magindex++) {
|
|
/* if main entry matches, print it... */
|
|
if (!mget(&p, s, &magic[magindex], nbytes) ||
|
|
!mcheck(&p, &magic[magindex])) {
|
|
/*
|
|
* main entry didn't match,
|
|
* flush its continuations
|
|
*/
|
|
while (magindex < nmagic &&
|
|
magic[magindex + 1].cont_level != 0)
|
|
magindex++;
|
|
continue;
|
|
}
|
|
|
|
mprint(&p, &magic[magindex]);
|
|
/*
|
|
* If we printed something, we'll need to print
|
|
* a blank before we print something else.
|
|
*/
|
|
if (magic[magindex].desc[0])
|
|
need_separator = 1;
|
|
/* and any continuations that match */
|
|
cont_level++;
|
|
while (magic[magindex+1].cont_level != 0 &&
|
|
++magindex < nmagic) {
|
|
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 (mget(&p, s, &magic[magindex], nbytes) &&
|
|
mcheck(&p, &magic[magindex])) {
|
|
/*
|
|
* This continuation matched.
|
|
* Print its message, with
|
|
* a blank before it if
|
|
* the previous item printed
|
|
* and this item isn't empty.
|
|
*/
|
|
/* space if previous printed */
|
|
if (need_separator
|
|
&& (magic[magindex].nospflag == 0)
|
|
&& (magic[magindex].desc[0] != '\0')
|
|
) {
|
|
(void) putchar(' ');
|
|
need_separator = 0;
|
|
}
|
|
mprint(&p, &magic[magindex]);
|
|
if (magic[magindex].desc[0])
|
|
need_separator = 1;
|
|
|
|
/*
|
|
* If we see any continuations
|
|
* at a higher level,
|
|
* process them.
|
|
*/
|
|
cont_level++;
|
|
}
|
|
}
|
|
}
|
|
return 1; /* all through */
|
|
}
|
|
return 0; /* no match at all */
|
|
}
|
|
|
|
static void
|
|
mprint(p, m)
|
|
union VALUETYPE *p;
|
|
struct magic *m;
|
|
{
|
|
char *pp, *rt;
|
|
unsigned long v;
|
|
|
|
|
|
switch (m->type) {
|
|
case BYTE:
|
|
v = p->b;
|
|
v = signextend(m, v) & m->mask;
|
|
(void) printf(m->desc, (unsigned char) v);
|
|
break;
|
|
|
|
case SHORT:
|
|
case BESHORT:
|
|
case LESHORT:
|
|
v = p->h;
|
|
v = signextend(m, v) & m->mask;
|
|
(void) printf(m->desc, (unsigned short) v);
|
|
break;
|
|
|
|
case LONG:
|
|
case BELONG:
|
|
case LELONG:
|
|
v = p->l;
|
|
v = signextend(m, v) & m->mask;
|
|
(void) printf(m->desc, (unsigned long) v);
|
|
break;
|
|
|
|
case STRING:
|
|
if (m->reln == '=') {
|
|
(void) printf(m->desc, m->value.s);
|
|
}
|
|
else {
|
|
(void) printf(m->desc, p->s);
|
|
}
|
|
return;
|
|
|
|
case DATE:
|
|
case BEDATE:
|
|
case LEDATE:
|
|
pp = ctime((time_t*) &p->l);
|
|
if ((rt = strchr(pp, '\n')) != NULL)
|
|
*rt = '\0';
|
|
(void) printf(m->desc, pp);
|
|
return;
|
|
default:
|
|
error("invalid m->type (%d) in mprint().\n", m->type);
|
|
/*NOTREACHED*/
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Convert the byte order of the data we are looking at
|
|
*/
|
|
static int
|
|
mconvert(p, m)
|
|
union VALUETYPE *p;
|
|
struct magic *m;
|
|
{
|
|
char *rt;
|
|
|
|
switch (m->type) {
|
|
case BYTE:
|
|
case SHORT:
|
|
case LONG:
|
|
case DATE:
|
|
return 1;
|
|
case STRING:
|
|
/* Null terminate and eat the return */
|
|
p->s[sizeof(p->s) - 1] = '\0';
|
|
if ((rt = strchr(p->s, '\n')) != NULL)
|
|
*rt = '\0';
|
|
return 1;
|
|
case BESHORT:
|
|
p->h = (short)((p->hs[0]<<8)|(p->hs[1]));
|
|
return 1;
|
|
case BELONG:
|
|
case BEDATE:
|
|
p->l = (long)
|
|
((p->hl[0]<<24)|(p->hl[1]<<16)|(p->hl[2]<<8)|(p->hl[3]));
|
|
return 1;
|
|
case LESHORT:
|
|
p->h = (short)((p->hs[1]<<8)|(p->hs[0]));
|
|
return 1;
|
|
case LELONG:
|
|
case LEDATE:
|
|
p->l = (long)
|
|
((p->hl[3]<<24)|(p->hl[2]<<16)|(p->hl[1]<<8)|(p->hl[0]));
|
|
return 1;
|
|
default:
|
|
error("invalid type %d in mconvert().\n", m->type);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
|
|
static void
|
|
mdebug(offset, str, len)
|
|
long offset;
|
|
char *str;
|
|
int len;
|
|
{
|
|
(void) fprintf(stderr, "mget @%ld: ", offset);
|
|
showstr(stderr, (char *) str, len);
|
|
(void) fputc('\n', stderr);
|
|
(void) fputc('\n', stderr);
|
|
}
|
|
|
|
static int
|
|
mget(p, s, m, nbytes)
|
|
union VALUETYPE* p;
|
|
unsigned char *s;
|
|
struct magic *m;
|
|
int nbytes;
|
|
{
|
|
long offset = m->offset;
|
|
|
|
if (offset + sizeof(union VALUETYPE) <= nbytes)
|
|
memcpy(p, s + offset, sizeof(union VALUETYPE));
|
|
else {
|
|
/*
|
|
* the usefulness of padding with zeroes eludes me, it
|
|
* might even cause problems
|
|
*/
|
|
long have = nbytes - offset;
|
|
memset(p, 0, sizeof(union VALUETYPE));
|
|
if (have > 0)
|
|
memcpy(p, s + offset, have);
|
|
}
|
|
|
|
|
|
if (debug) {
|
|
mdebug(offset, (char *) p, sizeof(union VALUETYPE));
|
|
mdump(m);
|
|
}
|
|
|
|
if (!mconvert(p, m))
|
|
return 0;
|
|
|
|
if (m->flag & INDIR) {
|
|
|
|
switch (m->in.type) {
|
|
case BYTE:
|
|
offset = p->b + m->in.offset;
|
|
break;
|
|
case SHORT:
|
|
offset = p->h + m->in.offset;
|
|
break;
|
|
case LONG:
|
|
offset = p->l + m->in.offset;
|
|
break;
|
|
}
|
|
|
|
if (offset + sizeof(union VALUETYPE) > nbytes)
|
|
return 0;
|
|
|
|
memcpy(p, s + offset, sizeof(union VALUETYPE));
|
|
|
|
if (debug) {
|
|
mdebug(offset, (char *) p, sizeof(union VALUETYPE));
|
|
mdump(m);
|
|
}
|
|
|
|
if (!mconvert(p, m))
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
mcheck(p, m)
|
|
union VALUETYPE* p;
|
|
struct magic *m;
|
|
{
|
|
register unsigned long l = m->value.l;
|
|
register unsigned long v;
|
|
int matched;
|
|
|
|
if ( (m->value.s[0] == 'x') && (m->value.s[1] == '\0') ) {
|
|
fprintf(stderr, "BOINK");
|
|
return 1;
|
|
}
|
|
|
|
|
|
switch (m->type) {
|
|
case BYTE:
|
|
v = p->b;
|
|
break;
|
|
|
|
case SHORT:
|
|
case BESHORT:
|
|
case LESHORT:
|
|
v = p->h;
|
|
break;
|
|
|
|
case LONG:
|
|
case BELONG:
|
|
case LELONG:
|
|
case DATE:
|
|
case BEDATE:
|
|
case LEDATE:
|
|
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;
|
|
default:
|
|
error("invalid type %d in mcheck().\n", m->type);
|
|
return 0;/*NOTREACHED*/
|
|
}
|
|
|
|
v = signextend(m, v) & m->mask;
|
|
|
|
switch (m->reln) {
|
|
case 'x':
|
|
if (debug)
|
|
(void) fprintf(stderr, "%lu == *any* = 1\n", v);
|
|
matched = 1;
|
|
break;
|
|
|
|
case '!':
|
|
matched = v != l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "%lu != %lu = %d\n",
|
|
v, l, matched);
|
|
break;
|
|
|
|
case '=':
|
|
matched = v == l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "%lu == %lu = %d\n",
|
|
v, l, matched);
|
|
break;
|
|
|
|
case '>':
|
|
if (m->flag & UNSIGNED) {
|
|
matched = v > l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "%lu > %lu = %d\n",
|
|
v, l, matched);
|
|
}
|
|
else {
|
|
matched = (long) v > (long) l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "%ld > %ld = %d\n",
|
|
v, l, matched);
|
|
}
|
|
break;
|
|
|
|
case '<':
|
|
if (m->flag & UNSIGNED) {
|
|
matched = v < l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "%lu < %lu = %d\n",
|
|
v, l, matched);
|
|
}
|
|
else {
|
|
matched = (long) v < (long) l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "%ld < %ld = %d\n",
|
|
v, l, matched);
|
|
}
|
|
break;
|
|
|
|
case '&':
|
|
matched = (v & l) == l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "((%lx & %lx) == %lx) = %d\n",
|
|
v, l, l, matched);
|
|
break;
|
|
|
|
case '^':
|
|
matched = (v & l) != l;
|
|
if (debug)
|
|
(void) fprintf(stderr, "((%lx & %lx) != %lx) = %d\n",
|
|
v, l, l, matched);
|
|
break;
|
|
|
|
default:
|
|
matched = 0;
|
|
error("mcheck: can't happen: invalid relation %d.\n", m->reln);
|
|
break;/*NOTREACHED*/
|
|
}
|
|
|
|
return matched;
|
|
}
|