329 lines
7.9 KiB
C
329 lines
7.9 KiB
C
/*
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* softmagic - interpret variable magic from /etc/magic
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*
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* Copyright (c) Ian F. Darwin, 1987.
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* Written by Ian F. Darwin.
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*
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* This software is not subject to any license of the American Telephone
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* and Telegraph Company or of the Regents of the University of California.
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*
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* Permission is granted to anyone to use this software for any purpose on
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* any computer system, and to alter it and redistribute it freely, subject
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* to the following restrictions:
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*
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* 1. The author is not responsible for the consequences of use of this
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* software, no matter how awful, even if they arise from flaws in it.
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*
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* 2. The origin of this software must not be misrepresented, either by
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* explicit claim or by omission. Since few users ever read sources,
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* credits must appear in the documentation.
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*
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* 3. Altered versions must be plainly marked as such, and must not be
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* misrepresented as being the original software. Since few users
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* ever read sources, credits must appear in the documentation.
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*
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* 4. This notice may not be removed or altered.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <time.h>
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#include <sys/types.h>
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#include "file.h"
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#ifndef lint
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static char *moduleid =
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"@(#)$Id: softmagic.c,v 1.2 1993/06/10 00:38:18 jtc Exp $";
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#endif /* lint */
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static int match __P((unsigned char *));
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static int mcheck __P((unsigned char *, struct magic *));
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static void mprint __P((struct magic *, unsigned char *));
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/*
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* softmagic - lookup one file in database
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* (already read from /etc/magic by apprentice.c).
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* Passed the name and FILE * of one file to be typed.
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*/
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/*ARGSUSED1*/ /* nbytes passed for regularity, maybe need later */
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int
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softmagic(buf, nbytes)
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unsigned char *buf;
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int nbytes;
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{
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if (match(buf))
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return 1;
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return 0;
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}
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/*
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* Go through the whole list, stopping if you find a match. Process all
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* the continuations of that match before returning.
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*
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* We support multi-level continuations:
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*
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* At any time when processing a successful top-level match, there is a
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* current continuation level; it represents the level of the last
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* successfully matched continuation.
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*
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* Continuations above that level are skipped as, if we see one, it
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* means that the continuation that controls them - i.e, the
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* lower-level continuation preceding them - failed to match.
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*
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* Continuations below that level are processed as, if we see one,
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* it means we've finished processing or skipping higher-level
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* continuations under the control of a successful or unsuccessful
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* lower-level continuation, and are now seeing the next lower-level
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* continuation and should process it. The current continuation
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* level reverts to the level of the one we're seeing.
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*
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* Continuations at the current level are processed as, if we see
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* one, there's no lower-level continuation that may have failed.
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*
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* If a continuation matches, we bump the current continuation level
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* so that higher-level continuations are processed.
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*/
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static int
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match(s)
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unsigned char *s;
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{
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int magindex = 0;
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int cont_level = 0;
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int need_separator = 0;
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while (magindex < nmagic) {
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/* if main entry matches, print it... */
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if (mcheck(s, &magic[magindex])) {
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mprint(&magic[magindex],s);
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/*
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* If we printed something, we'll need to print
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* a blank before we print something else.
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*/
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if (magic[magindex].desc[0])
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need_separator = 1;
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/* and any continuations that match */
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cont_level++;
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while (magic[magindex+1].cont_level != 0 &&
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magindex < nmagic) {
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++magindex;
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if (cont_level >=
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magic[magindex].cont_level) {
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if (cont_level >
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magic[magindex].cont_level) {
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/*
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* We're at the end of the
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* level-"cont_level"
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* continuations.
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*/
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cont_level =
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magic[magindex].cont_level;
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}
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if (mcheck(s, &magic[magindex])) {
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/*
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* This continuation matched.
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* Print its message, with
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* a blank before it if
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* the previous item printed
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* and this item isn't empty.
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*/
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/* space if previous printed */
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if (need_separator
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&& (magic[magindex].nospflag == 0)
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&& (magic[magindex].desc[0] != '\0')
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) {
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(void) putchar(' ');
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need_separator = 0;
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}
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mprint(&magic[magindex],s);
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if (magic[magindex].desc[0])
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need_separator = 1;
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/*
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* If we see any continuations
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* at a higher level,
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* process them.
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*/
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cont_level++;
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}
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}
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}
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return 1; /* all through */
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} else {
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/* main entry didn't match, flush its continuation */
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while (magic[magindex+1].cont_level != 0 &&
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magindex < nmagic) {
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++magindex;
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}
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}
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++magindex; /* on to the next */
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}
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return 0; /* no match at all */
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}
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static void
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mprint(m, s)
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struct magic *m;
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unsigned char *s;
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{
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register union VALUETYPE *p = (union VALUETYPE *)(s+m->offset);
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char *pp, *rt;
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/* correct byte order dependancies */
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switch (m->type) {
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case BESHORT:
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p->h = (short)((p->hs[0]<<8)|(p->hs[1]));
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break;
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case BELONG:
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case BEDATE:
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p->l = (long)
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((p->hl[0]<<24)|(p->hl[1]<<16)|(p->hl[2]<<8)|(p->hl[3]));
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break;
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case LESHORT:
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p->h = (short)((p->hs[1]<<8)|(p->hs[0]));
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break;
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case LELONG:
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case LEDATE:
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p->l = (long)
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((p->hl[3]<<24)|(p->hl[2]<<16)|(p->hl[1]<<8)|(p->hl[0]));
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break;
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}
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switch (m->type) {
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case BYTE:
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(void) printf(m->desc,
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(m->reln & MASK) ? p->b & m->mask : p->b);
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break;
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case SHORT:
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case BESHORT:
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case LESHORT:
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(void) printf(m->desc,
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(m->reln & MASK) ? p->h & m->mask : p->h);
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break;
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case LONG:
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case BELONG:
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case LELONG:
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(void) printf(m->desc,
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(m->reln & MASK) ? p->l & m->mask : p->l);
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break;
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case STRING:
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if ((rt=strchr(p->s, '\n')) != NULL)
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*rt = '\0';
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(void) printf(m->desc, p->s);
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if (rt)
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*rt = '\n';
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break;
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case DATE:
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case BEDATE:
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case LEDATE:
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pp = ctime((time_t*) &p->l);
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if ((rt = strchr(pp, '\n')) != NULL)
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*rt = '\0';
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(void) printf(m->desc, pp);
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if (rt)
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*rt = '\n';
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break;
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default:
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error("invalid m->type (%d) in mprint().\n", m->type);
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/*NOTREACHED*/
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}
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}
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static int
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mcheck(s, m)
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unsigned char *s;
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struct magic *m;
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{
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register union VALUETYPE *p = (union VALUETYPE *)(s+m->offset);
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register long l = m->value.l;
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register long mask = m->mask;
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register long v;
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if (debug) {
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(void) printf("mcheck: %10.10s ", s);
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mdump(m);
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}
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if ( (m->value.s[0] == 'x') && (m->value.s[1] == '\0') ) {
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printf("BOINK");
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return 1;
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}
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switch (m->type) {
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case BYTE:
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v = p->b; break;
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case SHORT:
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v = p->h; break;
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case LONG:
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case DATE:
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v = p->l; break;
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case STRING:
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l = 0;
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/* What we want here is:
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* v = strncmp(m->value.s, p->s, m->vallen);
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* but ignoring any nulls. bcmp doesn't give -/+/0
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* and isn't universally available anyway.
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*/
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v = 0;
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{
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register unsigned char *a = (unsigned char*)m->value.s;
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register unsigned char *b = (unsigned char*)p->s;
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register int len = m->vallen;
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while (--len >= 0)
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if ((v = *b++ - *a++) != 0)
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break;
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}
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break;
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case BESHORT:
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v = (short)((p->hs[0]<<8)|(p->hs[1]));
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break;
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case BELONG:
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case BEDATE:
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v = (long)
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((p->hl[0]<<24)|(p->hl[1]<<16)|(p->hl[2]<<8)|(p->hl[3]));
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break;
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case LESHORT:
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v = (short)((p->hs[1]<<8)|(p->hs[0]));
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break;
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case LELONG:
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case LEDATE:
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v = (long)
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((p->hl[3]<<24)|(p->hl[2]<<16)|(p->hl[1]<<8)|(p->hl[0]));
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break;
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default:
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error("invalid type %d in mcheck().\n", m->type);
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return -1;/*NOTREACHED*/
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}
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if (m->mask != 0L)
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v &= m->mask;
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switch (m->reln) {
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case 'x':
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return 1;
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case '!':
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return v != l;
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case '=':
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return v == l;
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case '>':
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return v > l;
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case '<':
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return v < l;
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case '&':
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return (v & l) == l;
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case '^':
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return (v & l) != l;
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case MASK | '=':
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return (v & mask) == l;
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case MASK | '>':
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return (v & mask) > l;
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case MASK | '<':
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return (v & mask) < l;
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default:
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error("mcheck: can't happen: invalid relation %d.\n", m->reln);
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return -1;/*NOTREACHED*/
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}
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}
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