385 lines
9.0 KiB
C
385 lines
9.0 KiB
C
/* @(#)softmagic.c 1.12 09/07/11 joerg */
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#include <schily/mconfig.h>
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#ifndef lint
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static UConst char sccsid[] =
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"@(#)softmagic.c 1.12 09/07/11 joerg";
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#endif
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/*
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** find file types by using a modified "magic" file
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**
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** based on file v3.22 by Ian F. Darwin (see below)
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**
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** Modified for mkhybrid James Pearson 19/5/98
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*/
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/*
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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 export provision of the United States
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* Department of Commerce, and may be exported to any country or planet.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice immediately at the beginning of the file, without modification,
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* this list of conditions, and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <schily/stdio.h>
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#include <schily/string.h>
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#include <schily/stdlib.h>
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#include <schily/schily.h>
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#include "file.h"
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#ifndef lint
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static UConst char moduleid[] =
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"@(#)$Id: softmagic.c,v 1.34 1997/01/15 19:28:35 christos Exp $";
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#endif /* lint */
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#ifdef DEBUG
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int debug = 1; /* debugging */
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#else
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#define debug 0 /* debugging */
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#endif /* DEBUG */
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/* static int match __PR((unsigned char *, int)); */
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static char *match __PR((unsigned char *, int));
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static int mget __PR((union VALUETYPE *,
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unsigned char *, struct magic *, int));
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/* QNX has a mcheck() prototyp in a public include file */
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static int magcheck __PR((union VALUETYPE *, struct magic *));
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#ifdef __used__
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static void mdebug __PR((Int32_t, char *, int));
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#endif
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static int mconvert __PR((union VALUETYPE *, struct magic *));
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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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char *
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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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return (match(buf, nbytes));
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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 char *
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match(s, nbytes)
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unsigned char *s;
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int nbytes;
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{
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int magindex = 0;
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union VALUETYPE p;
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for (magindex = 0; magindex < __f_nmagic; magindex++) {
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/* if main entry matches, print it... */
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if (!mget(&p, s, &__f_magic[magindex], nbytes) ||
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!magcheck(&p, &__f_magic[magindex])) {
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/*
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* main entry didn't match,
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* flush its continuations
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*/
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while (magindex < __f_nmagic &&
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__f_magic[magindex + 1].cont_level != 0)
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magindex++;
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continue;
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}
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return (__f_magic[magindex].desc);
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}
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return 0; /* no match at all */
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}
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/*
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* Convert the byte order of the data we are looking at
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*/
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static int
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mconvert(p, m)
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union VALUETYPE *p;
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struct magic *m;
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{
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switch (m->type) {
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case BYTE:
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case SHORT:
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case LONG:
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case DATE:
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return 1;
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case STRING:
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{
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char *ptr;
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/* Null terminate and eat the return */
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p->s[sizeof(p->s) - 1] = '\0';
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if ((ptr = strchr(p->s, '\n')) != NULL)
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*ptr = '\0';
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return 1;
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}
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case BESHORT:
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p->h = (short)((p->hs[0]<<8)|(p->hs[1]));
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return 1;
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case BELONG:
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case BEDATE:
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p->l = (Int32_t)
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((p->hl[0]<<24)|(p->hl[1]<<16)|(p->hl[2]<<8)|(p->hl[3]));
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return 1;
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case LESHORT:
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p->h = (short)((p->hs[1]<<8)|(p->hs[0]));
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return 1;
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case LELONG:
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case LEDATE:
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p->l = (Int32_t)
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((p->hl[3]<<24)|(p->hl[2]<<16)|(p->hl[1]<<8)|(p->hl[0]));
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return 1;
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default:
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return 0;
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}
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}
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#ifdef __used__
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static void
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mdebug(offset, str, len)
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Int32_t offset;
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char *str;
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int len;
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{
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(void) fprintf(stderr, "mget @%d: ", offset);
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showstr(stderr, (char *) str, len);
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(void) fputc('\n', stderr);
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(void) fputc('\n', stderr);
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}
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#endif
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static int
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mget(p, s, m, nbytes)
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union VALUETYPE* p;
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unsigned char *s;
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struct magic *m;
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int nbytes;
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{
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Int32_t offset = m->offset;
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if (offset + sizeof(union VALUETYPE) <= nbytes)
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memcpy(p, s + offset, sizeof(union VALUETYPE));
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else {
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/*
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* the usefulness of padding with zeroes eludes me, it
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* might even cause problems
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*/
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Int32_t have = nbytes - offset;
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memset(p, 0, sizeof(union VALUETYPE));
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if (have > 0)
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memcpy(p, s + offset, have);
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}
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if (!mconvert(p, m))
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return 0;
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if (m->flag & INDIR) {
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switch (m->in.type) {
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case BYTE:
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offset = p->b + m->in.offset;
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break;
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case SHORT:
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offset = p->h + m->in.offset;
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break;
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case LONG:
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offset = p->l + m->in.offset;
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break;
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}
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if (offset + sizeof(union VALUETYPE) > nbytes)
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return 0;
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memcpy(p, s + offset, sizeof(union VALUETYPE));
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if (!mconvert(p, m))
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return 0;
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}
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return 1;
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}
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static int
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magcheck(p, m)
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union VALUETYPE* p;
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struct magic *m;
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{
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register UInt32_t l = m->value.l;
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register UInt32_t v;
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int matched;
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if ( (m->value.s[0] == 'x') && (m->value.s[1] == '\0') ) {
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fprintf(stderr, "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;
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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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v = 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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case DATE:
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case BEDATE:
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case LEDATE:
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v = p->l;
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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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default:
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return 0;/*NOTREACHED*/
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}
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v = signextend(m, v) & m->mask;
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switch (m->reln) {
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case 'x':
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if (debug)
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(void) fprintf(stderr, "%u == *any* = 1\n", v);
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matched = 1;
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break;
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case '!':
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matched = v != l;
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if (debug)
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(void) fprintf(stderr, "%u != %u = %d\n",
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v, l, matched);
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break;
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case '=':
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matched = v == l;
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if (debug)
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(void) fprintf(stderr, "%u == %u = %d\n",
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v, l, matched);
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break;
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case '>':
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if (m->flag & UNSIGNED) {
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matched = v > l;
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if (debug)
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(void) fprintf(stderr, "%u > %u = %d\n",
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v, l, matched);
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}
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else {
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matched = (Int32_t) v > (Int32_t) l;
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if (debug)
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(void) fprintf(stderr, "%d > %d = %d\n",
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(Int32_t)v, (Int32_t)l, matched);
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}
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break;
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case '<':
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if (m->flag & UNSIGNED) {
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matched = v < l;
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if (debug)
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(void) fprintf(stderr, "%u < %u = %d\n",
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v, l, matched);
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}
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else {
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matched = (Int32_t) v < (Int32_t) l;
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if (debug)
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(void) fprintf(stderr, "%d < %d = %d\n",
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(Int32_t)v, (Int32_t)l, matched);
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}
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break;
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case '&':
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matched = (v & l) == l;
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if (debug)
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(void) fprintf(stderr, "((%x & %x) == %x) = %d\n",
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v, l, l, matched);
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break;
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case '^':
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matched = (v & l) != l;
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if (debug)
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(void) fprintf(stderr, "((%x & %x) != %x) = %d\n",
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v, l, l, matched);
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break;
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default:
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matched = 0;
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break;/*NOTREACHED*/
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}
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return matched;
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}
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