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freebsd-skq/contrib/file/softmagic.c

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/*
* 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 <ctype.h>
#include <stdlib.h>
#include <time.h>
#include <sys/types.h>
#include "file.h"
#ifndef lint
FILE_RCSID("@(#)$Id: softmagic.c,v 1.43 2001/03/11 20:29:16 christos Exp $")
#endif /* lint */
static int match __P((struct magic *, uint32, unsigned char *, int));
static int mget __P((union VALUETYPE *,
unsigned char *, struct magic *, int));
static int mcheck __P((union VALUETYPE *, struct magic *));
static int32 mprint __P((union VALUETYPE *, struct magic *));
static void mdebug __P((int32, 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;
{
struct mlist *ml;
for (ml = mlist.next; ml != &mlist; ml = ml->next)
if (match(ml->magic, ml->nmagic, 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(magic, nmagic, s, nbytes)
struct magic *magic;
uint32 nmagic;
unsigned char *s;
int nbytes;
{
int magindex = 0;
int cont_level = 0;
int need_separator = 0;
union VALUETYPE p;
static int32 *tmpoff = NULL;
static size_t tmplen = 0;
int32 oldoff = 0;
int returnval = 0; /* if a match is found it is set to 1*/
extern int kflag;
int firstline = 1; /* a flag to print X\n X\n- X */
struct mlist *ml;
if (tmpoff == NULL)
if ((tmpoff = (int32 *) malloc(tmplen = 20)) == NULL)
error("out of memory\n");
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;
}
if (! firstline) { /* we found another match */
/* put a newline and '-' to do some simple formatting*/
printf("\n- ");
}
tmpoff[cont_level] = 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 */
if (++cont_level >= tmplen)
if ((tmpoff = (int32 *) realloc(tmpoff,
tmplen += 20)) == NULL)
error("out of memory\n");
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 (magic[magindex].flag & ADD) {
oldoff=magic[magindex].offset;
magic[magindex].offset +=
tmpoff[cont_level-1];
}
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;
}
tmpoff[cont_level] =
mprint(&p, &magic[magindex]);
if (magic[magindex].desc[0])
need_separator = 1;
/*
* If we see any continuations
* at a higher level,
* process them.
*/
if (++cont_level >= tmplen)
if ((tmpoff =
(int32 *) realloc(tmpoff,
tmplen += 20)) == NULL)
error("out of memory\n");
}
if (magic[magindex].flag & ADD) {
magic[magindex].offset = oldoff;
}
}
}
firstline = 0;
returnval = 1;
if (!kflag) {
return 1; /* don't keep searching */
}
}
return returnval; /* This is hit if -k is set or there is no match */
}
static int32
mprint(p, m)
union VALUETYPE *p;
struct magic *m;
{
char *pp, *rt;
uint32 v;
time_t curtime;
int32 t=0 ;
switch (m->type) {
case BYTE:
v = p->b;
v = signextend(m, v) & m->mask;
(void) printf(m->desc, (unsigned char) v);
t = m->offset + sizeof(char);
break;
case SHORT:
case BESHORT:
case LESHORT:
v = p->h;
v = signextend(m, v) & m->mask;
(void) printf(m->desc, (unsigned short) v);
t = m->offset + sizeof(short);
break;
case LONG:
case BELONG:
case LELONG:
v = p->l;
v = signextend(m, v) & m->mask;
(void) printf(m->desc, (uint32) v);
t = m->offset + sizeof(int32);
break;
case STRING:
if (m->reln == '=') {
(void) printf(m->desc, m->value.s);
t = m->offset + strlen(m->value.s);
}
else {
if (*m->value.s == '\0') {
char *cp = strchr(p->s,'\n');
if (cp)
*cp = '\0';
}
(void) printf(m->desc, p->s);
t = m->offset + strlen(p->s);
}
break;
case DATE:
case BEDATE:
case LEDATE:
curtime = p->l;
pp = ctime(&curtime);
if ((rt = strchr(pp, '\n')) != NULL)
*rt = '\0';
(void) printf(m->desc, pp);
t = m->offset + sizeof(time_t);
break;
default:
error("invalid m->type (%d) in mprint().\n", m->type);
/*NOTREACHED*/
}
return(t);
}
/*
* Convert the byte order of the data we are looking at
*/
static int
mconvert(p, m)
union VALUETYPE *p;
struct magic *m;
{
switch (m->type) {
case BYTE:
case SHORT:
case LONG:
case DATE:
return 1;
case STRING:
{
char *ptr;
/* Null terminate and eat the return */
p->s[sizeof(p->s) - 1] = '\0';
if ((ptr = strchr(p->s, '\n')) != NULL)
*ptr = '\0';
return 1;
}
case BESHORT:
p->h = (short)((p->hs[0]<<8)|(p->hs[1]));
return 1;
case BELONG:
case BEDATE:
p->l = (int32)
((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 = (int32)
((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)
int32 offset;
char *str;
int len;
{
(void) fprintf(stderr, "mget @%d: ", 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;
{
int32 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
*/
int32 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 (m->flag & INDIR) {
switch (m->in_type) {
case BYTE:
offset = p->b + m->in_offset;
break;
case BESHORT:
offset = (short)((p->hs[0]<<8)|(p->hs[1]))+
m->in_offset;
break;
case LESHORT:
offset = (short)((p->hs[1]<<8)|(p->hs[0]))+
m->in_offset;
break;
case SHORT:
offset = p->h + m->in_offset;
break;
case BELONG:
offset = (int32)((p->hl[0]<<24)|(p->hl[1]<<16)|
(p->hl[2]<<8)|(p->hl[3]))+
m->in_offset;
break;
case LELONG:
offset = (int32)((p->hl[3]<<24)|(p->hl[2]<<16)|
(p->hl[1]<<8)|(p->hl[0]))+
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;
{
uint32 l = m->value.l;
uint32 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: {
/*
* 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.
*/
unsigned char *a = (unsigned char*)m->value.s;
unsigned char *b = (unsigned char*)p->s;
int len = m->vallen;
l = 0;
v = 0;
if (0L == m->mask) { /* normal string: do it fast */
while (--len >= 0)
if ((v = *b++ - *a++) != '\0')
break;
} else { /* combine the others */
while (--len >= 0) {
if ((m->mask & STRING_IGNORE_LOWERCASE) &&
islower(*a)) {
if ((v = tolower(*b++) - *a++) != '\0')
break;
} else if ((m->mask & STRING_COMPACT_BLANK) &&
isspace(*a)) {
a++;
if (isspace(*b++)) {
while (isspace(*b))
b++;
} else {
v = 1;
break;
}
} else if (isspace(*a) &&
(m->mask & STRING_COMPACT_OPTIONAL_BLANK)) {
a++;
while (isspace(*b))
b++;
} else {
if ((v = *b++ - *a++) != '\0')
break;
}
}
}
break;
}
default:
error("invalid type %d in mcheck().\n", m->type);
return 0;/*NOTREACHED*/
}
if(m->type != STRING)
v = signextend(m, v) & m->mask;
switch (m->reln) {
case 'x':
if (debug)
(void) fprintf(stderr, "%u == *any* = 1\n", v);
matched = 1;
break;
case '!':
matched = v != l;
if (debug)
(void) fprintf(stderr, "%u != %u = %d\n",
v, l, matched);
break;
case '=':
matched = v == l;
if (debug)
(void) fprintf(stderr, "%u == %u = %d\n",
v, l, matched);
break;
case '>':
if (m->flag & UNSIGNED) {
matched = v > l;
if (debug)
(void) fprintf(stderr, "%u > %u = %d\n",
v, l, matched);
}
else {
matched = (int32) v > (int32) l;
if (debug)
(void) fprintf(stderr, "%d > %d = %d\n",
v, l, matched);
}
break;
case '<':
if (m->flag & UNSIGNED) {
matched = v < l;
if (debug)
(void) fprintf(stderr, "%u < %u = %d\n",
v, l, matched);
}
else {
matched = (int32) v < (int32) l;
if (debug)
(void) fprintf(stderr, "%d < %d = %d\n",
v, l, matched);
}
break;
case '&':
matched = (v & l) == l;
if (debug)
(void) fprintf(stderr, "((%x & %x) == %x) = %d\n",
v, l, l, matched);
break;
case '^':
matched = (v & l) != l;
if (debug)
(void) fprintf(stderr, "((%x & %x) != %x) = %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;
}
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