[unix-history] / usr.bin / file / softmagic.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 = 
	"@(#)softmagic.c,v 1.2 1993/06/10 00:38:18 jtc Exp";
#endif	/* lint */

static int match	__P((unsigned char *));
static int mcheck	__P((unsigned char	*, struct magic *));
static void mprint	__P((struct magic *, unsigned char *));

/*
 * 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;
	int need_separator = 0;

	while (magindex < nmagic) {
		/* if main entry matches, print it... */
		if (mcheck(s, &magic[magindex])) {
			mprint(&magic[magindex],s);
			/*
			 * 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) {
				++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.
						 * 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(&magic[magindex],s);
						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 */
		} 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(m, s)
struct magic *m;
unsigned char *s;
{
	register union VALUETYPE *p = (union VALUETYPE *)(s+m->offset);
	char *pp, *rt;

	/* correct byte order dependancies */
	switch (m->type) {
	case BESHORT:
		p->h = (short)((p->hs[0]<<8)|(p->hs[1]));
		break;
	case BELONG:
	case BEDATE:
		p->l = (long)
		    ((p->hl[0]<<24)|(p->hl[1]<<16)|(p->hl[2]<<8)|(p->hl[3]));
		break;
	case LESHORT:
		p->h = (short)((p->hs[1]<<8)|(p->hs[0]));
		break;
	case LELONG:
	case LEDATE:
		p->l = (long)
		    ((p->hl[3]<<24)|(p->hl[2]<<16)|(p->hl[1]<<8)|(p->hl[0]));
		break;
	}

  	switch (m->type) {
  	case BYTE:
 		(void) printf(m->desc,
 			      (m->reln & MASK) ? p->b & m->mask : p->b);
  		break;
  	case SHORT:
  	case BESHORT:
  	case LESHORT:
 		(void) printf(m->desc,
 			      (m->reln & MASK) ? p->h & m->mask : p->h);
  		break;
  	case LONG:
  	case BELONG:
  	case LELONG:
 		(void) printf(m->desc,
 			      (m->reln & MASK) ? p->l & m->mask : p->l);
  		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*) &p->l);
		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 long l = m->value.l;
	register long mask = m->mask;
	register long v;

	if (debug) {
		(void) printf("mcheck: %10.10s ", s);
		mdump(m);
	}

	if ( (m->value.s[0] == 'x') && (m->value.s[1] == '\0') ) {
		printf("BOINK");
		return 1;
	}

	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 = (short)((p->hs[0]<<8)|(p->hs[1]));
		break;
	case BELONG:
	case BEDATE:
		v = (long)
		    ((p->hl[0]<<24)|(p->hl[1]<<16)|(p->hl[2]<<8)|(p->hl[3]));
		break;
	case LESHORT:
		v = (short)((p->hs[1]<<8)|(p->hs[0]));
		break;
	case LELONG:
	case LEDATE:
		v = (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*/
	}

	if (m->mask != 0L)
		v &= m->mask;

	switch (m->reln) {
	case 'x':
		return 1;
	case '!':
		return v != l;
	case '=':
		return v == l;
	case '>':
		return v > l;
	case '<':
		return v < l;
	case '&':
		return (v & l) == l;
	case '^':
		return (v & l) != l;
	case MASK | '=':
		return (v & mask) == l;
	case MASK | '>':
		return (v & mask) > l;
	case MASK | '<':
		return (v & mask) < l;
	default:
		error("mcheck: can't happen: invalid relation %d.\n", m->reln);
		return -1;/*NOTREACHED*/
	}
}
Commit	Line	Data
15637ed4 RG	1	/*
	2	* softmagic - interpret variable magic from /etc/magic
	3	*
	4	* Copyright (c) Ian F. Darwin, 1987.
	5	* Written by Ian F. Darwin.
	6	*
	7	* This software is not subject to any license of the American Telephone
	8	* and Telegraph Company or of the Regents of the University of California.
	9	*
	10	* Permission is granted to anyone to use this software for any purpose on
	11	* any computer system, and to alter it and redistribute it freely, subject
	12	* to the following restrictions:
	13	*
	14	* 1. The author is not responsible for the consequences of use of this
	15	* software, no matter how awful, even if they arise from flaws in it.
	16	*
	17	* 2. The origin of this software must not be misrepresented, either by
	18	* explicit claim or by omission. Since few users ever read sources,
	19	* credits must appear in the documentation.
	20	*
	21	* 3. Altered versions must be plainly marked as such, and must not be
	22	* misrepresented as being the original software. Since few users
	23	* ever read sources, credits must appear in the documentation.
	24	*
	25	* 4. This notice may not be removed or altered.
	26	*/
	27
	28	#include <stdio.h>
78ed81a3	29	#include <string.h>
	30	#include <time.h>
	31	#include <sys/types.h>
	32
15637ed4 RG	33	#include "file.h"
	34
	35	#ifndef lint
	36	static char *moduleid =
78ed81a3	37	"@(#)softmagic.c,v 1.2 1993/06/10 00:38:18 jtc Exp";
15637ed4 RG	38	#endif /* lint */
15637ed4 RG	39
78ed81a3	40	static int match __P((unsigned char *));
	41	static int mcheck __P((unsigned char , struct magic ));
	42	static void mprint __P((struct magic , unsigned char ));
15637ed4 RG	43
	44	/*
	45	* softmagic - lookup one file in database
	46	* (already read from /etc/magic by apprentice.c).
	47	* Passed the name and FILE * of one file to be typed.
	48	*/
78ed81a3	49	/ARGSUSED1/ /* nbytes passed for regularity, maybe need later */
	50	int
	51	softmagic(buf, nbytes)
	52	unsigned char *buf;
	53	int nbytes;
15637ed4	54	{
15637ed4 RG	55	if (match(buf))
	56	return 1;
	57
	58	return 0;
	59	}
	60
	61	/*
78ed81a3	62	* Go through the whole list, stopping if you find a match. Process all
	63	* the continuations of that match before returning.
	64	*
	65	* We support multi-level continuations:
	66	*
	67	* At any time when processing a successful top-level match, there is a
	68	* current continuation level; it represents the level of the last
	69	* successfully matched continuation.
	70	*
	71	* Continuations above that level are skipped as, if we see one, it
	72	* means that the continuation that controls them - i.e, the
	73	* lower-level continuation preceding them - failed to match.
	74	*
	75	* Continuations below that level are processed as, if we see one,
	76	* it means we've finished processing or skipping higher-level
	77	* continuations under the control of a successful or unsuccessful
	78	* lower-level continuation, and are now seeing the next lower-level
	79	* continuation and should process it. The current continuation
	80	* level reverts to the level of the one we're seeing.
	81	*
	82	* Continuations at the current level are processed as, if we see
	83	* one, there's no lower-level continuation that may have failed.
	84	*
	85	* If a continuation matches, we bump the current continuation level
	86	* so that higher-level continuations are processed.
15637ed4	87	*/
78ed81a3	88	static int
15637ed4	89	match(s)
78ed81a3	90	unsigned char *s;
15637ed4	91	{
78ed81a3	92	int magindex = 0;
	93	int cont_level = 0;
	94	int need_separator = 0;
	95
15637ed4 RG	96	while (magindex < nmagic) {
	97	/* if main entry matches, print it... */
	98	if (mcheck(s, &magic[magindex])) {
	99	mprint(&magic[magindex],s);
78ed81a3	100	/*
	101	* If we printed something, we'll need to print
	102	* a blank before we print something else.
	103	*/
	104	if (magic[magindex].desc[0])
	105	need_separator = 1;
15637ed4	106	/* and any continuations that match */
78ed81a3	107	cont_level++;
78ed81a3	108	while (magic[magindex+1].cont_level != 0 &&
15637ed4 RG	109	magindex < nmagic) {
15637ed4 RG	110	++magindex;
78ed81a3	111	if (cont_level >=
	112	magic[magindex].cont_level) {
	113	if (cont_level >
	114	magic[magindex].cont_level) {
	115	/*
	116	* We're at the end of the
	117	* level-"cont_level"
	118	* continuations.
	119	*/
	120	cont_level =
	121	magic[magindex].cont_level;
	122	}
	123	if (mcheck(s, &magic[magindex])) {
	124	/*
	125	* This continuation matched.
	126	* Print its message, with
	127	* a blank before it if
	128	* the previous item printed
	129	* and this item isn't empty.
	130	*/
	131	/* space if previous printed */
	132	if (need_separator
	133	&& (magic[magindex].nospflag == 0)
	134	&& (magic[magindex].desc[0] != '\0')
	135	) {
	136	(void) putchar(' ');
	137	need_separator = 0;
	138	}
	139	mprint(&magic[magindex],s);
	140	if (magic[magindex].desc[0])
	141	need_separator = 1;
	142
	143	/*
	144	* If we see any continuations
	145	* at a higher level,
	146	* process them.
	147	*/
	148	cont_level++;
	149	}
15637ed4 RG	150	}
	151	}
	152	return 1; /* all through */
	153	} else {
78ed81a3	154	/* main entry didn't match, flush its continuation */
78ed81a3	155	while (magic[magindex+1].cont_level != 0 &&
15637ed4 RG	156	magindex < nmagic) {
	157	++magindex;
	158	}
	159	}
	160	++magindex; /* on to the next */
	161	}
	162	return 0; /* no match at all */
	163	}
	164
78ed81a3	165	static void
78ed81a3	166	mprint(m, s)
15637ed4	167	struct magic *m;
78ed81a3	168	unsigned char *s;
15637ed4 RG	169	{
15637ed4 RG	170	register union VALUETYPE p = (union VALUETYPE )(s+m->offset);
78ed81a3	171	char pp, rt;
15637ed4	172
78ed81a3	173	/* correct byte order dependancies */
15637ed4	174	switch (m->type) {
78ed81a3	175	case BESHORT:
78ed81a3	176	p->h = (short)((p->hs[0]<<8)\|(p->hs[1]));
15637ed4	177	break;
78ed81a3	178	case BELONG:
	179	case BEDATE:
	180	p->l = (long)
	181	((p->hl[0]<<24)\|(p->hl[1]<<16)\|(p->hl[2]<<8)\|(p->hl[3]));
15637ed4	182	break;
78ed81a3	183	case LESHORT:
78ed81a3	184	p->h = (short)((p->hs[1]<<8)\|(p->hs[0]));
15637ed4	185	break;
78ed81a3	186	case LELONG:
	187	case LEDATE:
	188	p->l = (long)
	189	((p->hl[3]<<24)\|(p->hl[2]<<16)\|(p->hl[1]<<8)\|(p->hl[0]));
	190	break;
	191	}
	192
	193	switch (m->type) {
	194	case BYTE:
	195	(void) printf(m->desc,
	196	(m->reln & MASK) ? p->b & m->mask : p->b);
	197	break;
	198	case SHORT:
	199	case BESHORT:
	200	case LESHORT:
	201	(void) printf(m->desc,
	202	(m->reln & MASK) ? p->h & m->mask : p->h);
	203	break;
	204	case LONG:
	205	case BELONG:
	206	case LELONG:
	207	(void) printf(m->desc,
	208	(m->reln & MASK) ? p->l & m->mask : p->l);
	209	break;
	210	case STRING:
	211	if ((rt=strchr(p->s, '\n')) != NULL)
	212	*rt = '\0';
15637ed4	213	(void) printf(m->desc, p->s);
78ed81a3	214	if (rt)
	215	*rt = '\n';
	216	break;
	217	case DATE:
	218	case BEDATE:
	219	case LEDATE:
	220	pp = ctime((time_t*) &p->l);
	221	if ((rt = strchr(pp, '\n')) != NULL)
	222	*rt = '\0';
	223	(void) printf(m->desc, pp);
	224	if (rt)
	225	*rt = '\n';
15637ed4 RG	226	break;
15637ed4 RG	227	default:
78ed81a3	228	error("invalid m->type (%d) in mprint().\n", m->type);
78ed81a3	229	/NOTREACHED/
15637ed4 RG	230	}
	231	}
	232
78ed81a3	233	static int
15637ed4	234	mcheck(s, m)
78ed81a3	235	unsigned char *s;
15637ed4 RG	236	struct magic *m;
	237	{
	238	register union VALUETYPE p = (union VALUETYPE )(s+m->offset);
	239	register long l = m->value.l;
78ed81a3	240	register long mask = m->mask;
15637ed4 RG	241	register long v;
	242
	243	if (debug) {
	244	(void) printf("mcheck: %10.10s ", s);
	245	mdump(m);
	246	}
78ed81a3	247
	248	if ( (m->value.s[0] == 'x') && (m->value.s[1] == '\0') ) {
	249	printf("BOINK");
	250	return 1;
	251	}
	252
15637ed4 RG	253	switch (m->type) {
	254	case BYTE:
	255	v = p->b; break;
	256	case SHORT:
	257	v = p->h; break;
	258	case LONG:
78ed81a3	259	case DATE:
15637ed4 RG	260	v = p->l; break;
	261	case STRING:
	262	l = 0;
	263	/* What we want here is:
	264	* v = strncmp(m->value.s, p->s, m->vallen);
	265	* but ignoring any nulls. bcmp doesn't give -/+/0
	266	* and isn't universally available anyway.
	267	*/
78ed81a3	268	v = 0;
15637ed4 RG	269	{
	270	register unsigned char a = (unsigned char)m->value.s;
	271	register unsigned char b = (unsigned char)p->s;
	272	register int len = m->vallen;
	273
	274	while (--len >= 0)
	275	if ((v = b++ - a++) != 0)
	276	break;
	277	}
	278	break;
78ed81a3	279	case BESHORT:
	280	v = (short)((p->hs[0]<<8)\|(p->hs[1]));
	281	break;
	282	case BELONG:
	283	case BEDATE:
	284	v = (long)
	285	((p->hl[0]<<24)\|(p->hl[1]<<16)\|(p->hl[2]<<8)\|(p->hl[3]));
	286	break;
	287	case LESHORT:
	288	v = (short)((p->hs[1]<<8)\|(p->hs[0]));
	289	break;
	290	case LELONG:
	291	case LEDATE:
	292	v = (long)
	293	((p->hl[3]<<24)\|(p->hl[2]<<16)\|(p->hl[1]<<8)\|(p->hl[0]));
	294	break;
15637ed4	295	default:
78ed81a3	296	error("invalid type %d in mcheck().\n", m->type);
78ed81a3	297	return -1;/NOTREACHED/
15637ed4 RG	298	}
15637ed4 RG	299
78ed81a3	300	if (m->mask != 0L)
	301	v &= m->mask;
	302
15637ed4	303	switch (m->reln) {
78ed81a3	304	case 'x':
	305	return 1;
	306	case '!':
	307	return v != l;
15637ed4 RG	308	case '=':
	309	return v == l;
	310	case '>':
	311	return v > l;
	312	case '<':
	313	return v < l;
	314	case '&':
78ed81a3	315	return (v & l) == l;
	316	case '^':
	317	return (v & l) != l;
	318	case MASK \| '=':
	319	return (v & mask) == l;
	320	case MASK \| '>':
	321	return (v & mask) > l;
	322	case MASK \| '<':
	323	return (v & mask) < l;
15637ed4	324	default:
78ed81a3	325	error("mcheck: can't happen: invalid relation %d.\n", m->reln);
78ed81a3	326	return -1;/NOTREACHED/
15637ed4 RG	327	}
15637ed4 RG	328	}