compress.c revision 169962 
1/*
2 * Copyright (c) Ian F. Darwin 1986-1995.
3 * Software written by Ian F. Darwin and others;
4 * maintained 1995-present by Christos Zoulas and others.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice immediately at the beginning of the file, without modification,
11 *    this list of conditions, and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28/*
29 * compress routines:
30 *	zmagic() - returns 0 if not recognized, uncompresses and prints
31 *		   information if recognized
32 *	uncompress(method, old, n, newch) - uncompress old into new,
33 *					    using method, return sizeof new
34 */
35#include "file.h"
36#include "magic.h"
37#include <stdio.h>
38#include <stdlib.h>
39#ifdef HAVE_UNISTD_H
40#include <unistd.h>
41#endif
42#include <string.h>
43#include <errno.h>
44#include <sys/types.h>
45#include <sys/ioctl.h>
46#ifdef HAVE_SYS_WAIT_H
47#include <sys/wait.h>
48#endif
49#if defined(HAVE_SYS_TIME_H)
50#include <sys/time.h>
51#endif
52#ifdef HAVE_LIBZ
53#include <zlib.h>
54#endif
55
56
57#ifndef lint
58FILE_RCSID("@(#)$File: compress.c,v 1.51 2007/03/05 02:41:29 christos Exp $")
59#endif
60
61private struct {
62	const char *magic;
63	size_t maglen;
64	const char *const argv[3];
65	int silent;
66} compr[] = {
67	{ "\037\235", 2, { "gzip", "-cdq", NULL }, 1 },		/* compressed */
68	/* Uncompress can get stuck; so use gzip first if we have it
69	 * Idea from Damien Clark, thanks! */
70	{ "\037\235", 2, { "uncompress", "-c", NULL }, 1 },	/* compressed */
71	{ "\037\213", 2, { "gzip", "-cdq", NULL }, 1 },		/* gzipped */
72	{ "\037\236", 2, { "gzip", "-cdq", NULL }, 1 },		/* frozen */
73	{ "\037\240", 2, { "gzip", "-cdq", NULL }, 1 },		/* SCO LZH */
74	/* the standard pack utilities do not accept standard input */
75	{ "\037\036", 2, { "gzip", "-cdq", NULL }, 0 },		/* packed */
76	{ "PK\3\4",   4, { "gzip", "-cdq", NULL }, 1 },		/* pkzipped, */
77					    /* ...only first file examined */
78	{ "BZh",      3, { "bzip2", "-cd", NULL }, 1 },		/* bzip2-ed */
79};
80
81private size_t ncompr = sizeof(compr) / sizeof(compr[0]);
82
83#define NODATA ((size_t)~0)
84
85
86private ssize_t swrite(int, const void *, size_t);
87private size_t uncompressbuf(struct magic_set *, int, size_t,
88    const unsigned char *, unsigned char **, size_t);
89#ifdef HAVE_LIBZ
90private size_t uncompressgzipped(struct magic_set *, const unsigned char *,
91    unsigned char **, size_t);
92#endif
93
94protected int
95file_zmagic(struct magic_set *ms, int fd, const char *name,
96    const unsigned char *buf, size_t nbytes)
97{
98	unsigned char *newbuf = NULL;
99	size_t i, nsz;
100	int rv = 0;
101
102	if ((ms->flags & MAGIC_COMPRESS) == 0)
103		return 0;
104
105	for (i = 0; i < ncompr; i++) {
106		if (nbytes < compr[i].maglen)
107			continue;
108		if (memcmp(buf, compr[i].magic, compr[i].maglen) == 0 &&
109		    (nsz = uncompressbuf(ms, fd, i, buf, &newbuf,
110		    nbytes)) != NODATA) {
111			ms->flags &= ~MAGIC_COMPRESS;
112			rv = -1;
113			if (file_buffer(ms, -1, name, newbuf, nsz) == -1)
114				goto error;
115			if (file_printf(ms, " (") == -1)
116				goto error;
117			if (file_buffer(ms, -1, NULL, buf, nbytes) == -1)
118				goto error;
119			if (file_printf(ms, ")") == -1)
120				goto error;
121			rv = 1;
122			break;
123		}
124	}
125error:
126	if (newbuf)
127		free(newbuf);
128	ms->flags |= MAGIC_COMPRESS;
129	return rv;
130}
131
132/*
133 * `safe' write for sockets and pipes.
134 */
135private ssize_t
136swrite(int fd, const void *buf, size_t n)
137{
138	int rv;
139	size_t rn = n;
140
141	do
142		switch (rv = write(fd, buf, n)) {
143		case -1:
144			if (errno == EINTR)
145				continue;
146			return -1;
147		default:
148			n -= rv;
149			buf = ((const char *)buf) + rv;
150			break;
151		}
152	while (n > 0);
153	return rn;
154}
155
156
157/*
158 * `safe' read for sockets and pipes.
159 */
160protected ssize_t
161sread(int fd, void *buf, size_t n, int canbepipe)
162{
163	int rv, cnt;
164#ifdef FIONREAD
165	int t = 0;
166#endif
167	size_t rn = n;
168
169	if (fd == STDIN_FILENO)
170		goto nocheck;
171
172#ifdef FIONREAD
173	if ((canbepipe && (ioctl(fd, FIONREAD, &t) == -1)) || (t == 0)) {
174#ifdef FD_ZERO
175		for (cnt = 0;; cnt++) {
176			fd_set check;
177			struct timeval tout = {0, 100 * 1000};
178			int selrv;
179
180			FD_ZERO(&check);
181			FD_SET(fd, &check);
182
183			/*
184			 * Avoid soft deadlock: do not read if there
185			 * is nothing to read from sockets and pipes.
186			 */
187			selrv = select(fd + 1, &check, NULL, NULL, &tout);
188			if (selrv == -1) {
189				if (errno == EINTR || errno == EAGAIN)
190					continue;
191			} else if (selrv == 0 && cnt >= 5) {
192				return 0;
193			} else
194				break;
195		}
196#endif
197		(void)ioctl(fd, FIONREAD, &t);
198	}
199
200	if (t > 0 && (size_t)t < n) {
201		n = t;
202		rn = n;
203	}
204#endif
205
206nocheck:
207	do
208		switch ((rv = read(fd, buf, n))) {
209		case -1:
210			if (errno == EINTR)
211				continue;
212			return -1;
213		case 0:
214			return rn - n;
215		default:
216			n -= rv;
217			buf = ((char *)buf) + rv;
218			break;
219		}
220	while (n > 0);
221	return rn;
222}
223
224protected int
225file_pipe2file(struct magic_set *ms, int fd, const void *startbuf,
226    size_t nbytes)
227{
228	char buf[4096];
229	int r, tfd;
230
231	(void)strcpy(buf, "/tmp/file.XXXXXX");
232#ifndef HAVE_MKSTEMP
233	{
234		char *ptr = mktemp(buf);
235		tfd = open(ptr, O_RDWR|O_TRUNC|O_EXCL|O_CREAT, 0600);
236		r = errno;
237		(void)unlink(ptr);
238		errno = r;
239	}
240#else
241	tfd = mkstemp(buf);
242	r = errno;
243	(void)unlink(buf);
244	errno = r;
245#endif
246	if (tfd == -1) {
247		file_error(ms, errno,
248		    "cannot create temporary file for pipe copy");
249		return -1;
250	}
251
252	if (swrite(tfd, startbuf, nbytes) != (ssize_t)nbytes)
253		r = 1;
254	else {
255		while ((r = sread(fd, buf, sizeof(buf), 1)) > 0)
256			if (swrite(tfd, buf, (size_t)r) != r)
257				break;
258	}
259
260	switch (r) {
261	case -1:
262		file_error(ms, errno, "error copying from pipe to temp file");
263		return -1;
264	case 0:
265		break;
266	default:
267		file_error(ms, errno, "error while writing to temp file");
268		return -1;
269	}
270
271	/*
272	 * We duplicate the file descriptor, because fclose on a
273	 * tmpfile will delete the file, but any open descriptors
274	 * can still access the phantom inode.
275	 */
276	if ((fd = dup2(tfd, fd)) == -1) {
277		file_error(ms, errno, "could not dup descriptor for temp file");
278		return -1;
279	}
280	(void)close(tfd);
281	if (lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) {
282		file_badseek(ms);
283		return -1;
284	}
285	return fd;
286}
287
288#ifdef HAVE_LIBZ
289
290#define FHCRC		(1 << 1)
291#define FEXTRA		(1 << 2)
292#define FNAME		(1 << 3)
293#define FCOMMENT	(1 << 4)
294
295private size_t
296uncompressgzipped(struct magic_set *ms, const unsigned char *old,
297    unsigned char **newch, size_t n)
298{
299	unsigned char flg = old[3];
300	size_t data_start = 10;
301	z_stream z;
302	int rc;
303
304	if (flg & FEXTRA) {
305		if (data_start+1 >= n)
306			return 0;
307		data_start += 2 + old[data_start] + old[data_start + 1] * 256;
308	}
309	if (flg & FNAME) {
310		while(data_start < n && old[data_start])
311			data_start++;
312		data_start++;
313	}
314	if(flg & FCOMMENT) {
315		while(data_start < n && old[data_start])
316			data_start++;
317		data_start++;
318	}
319	if(flg & FHCRC)
320		data_start += 2;
321
322	if (data_start >= n)
323		return 0;
324	if ((*newch = (unsigned char *)malloc(HOWMANY + 1)) == NULL) {
325		return 0;
326	}
327
328	/* XXX: const castaway, via strchr */
329	z.next_in = (Bytef *)strchr((const char *)old + data_start,
330	    old[data_start]);
331	z.avail_in = n - data_start;
332	z.next_out = *newch;
333	z.avail_out = HOWMANY;
334	z.zalloc = Z_NULL;
335	z.zfree = Z_NULL;
336	z.opaque = Z_NULL;
337
338	rc = inflateInit2(&z, -15);
339	if (rc != Z_OK) {
340		file_error(ms, 0, "zlib: %s", z.msg);
341		return 0;
342	}
343
344	rc = inflate(&z, Z_SYNC_FLUSH);
345	if (rc != Z_OK && rc != Z_STREAM_END) {
346		file_error(ms, 0, "zlib: %s", z.msg);
347		return 0;
348	}
349
350	n = (size_t)z.total_out;
351	(void)inflateEnd(&z);
352
353	/* let's keep the nul-terminate tradition */
354	(*newch)[n] = '\0';
355
356	return n;
357}
358#endif
359
360private size_t
361uncompressbuf(struct magic_set *ms, int fd, size_t method,
362    const unsigned char *old, unsigned char **newch, size_t n)
363{
364	int fdin[2], fdout[2];
365	int r;
366
367#ifdef HAVE_LIBZ
368	if (method == 2)
369		return uncompressgzipped(ms, old, newch, n);
370#endif
371	(void)fflush(stdout);
372	(void)fflush(stderr);
373
374	if ((fd != -1 && pipe(fdin) == -1) || pipe(fdout) == -1) {
375		file_error(ms, errno, "cannot create pipe");
376		return NODATA;
377	}
378	switch (fork()) {
379	case 0:	/* child */
380		(void) close(0);
381		if (fd != -1) {
382		    (void) dup(fd);
383		    (void) lseek(0, (off_t)0, SEEK_SET);
384		} else {
385		    (void) dup(fdin[0]);
386		    (void) close(fdin[0]);
387		    (void) close(fdin[1]);
388		}
389
390		(void) close(1);
391		(void) dup(fdout[1]);
392		(void) close(fdout[0]);
393		(void) close(fdout[1]);
394#ifndef DEBUG
395		if (compr[method].silent)
396			(void)close(2);
397#endif
398
399		(void)execvp(compr[method].argv[0],
400		    (char *const *)(intptr_t)compr[method].argv);
401#ifdef DEBUG
402		(void)fprintf(stderr, "exec `%s' failed (%s)\n",
403		    compr[method].argv[0], strerror(errno));
404#endif
405		exit(1);
406		/*NOTREACHED*/
407	case -1:
408		file_error(ms, errno, "could not fork");
409		return NODATA;
410
411	default: /* parent */
412		(void) close(fdout[1]);
413		if (fd == -1) {
414			(void) close(fdin[0]);
415			/*
416			 * fork again, to avoid blocking because both
417			 * pipes filled
418			 */
419			switch (fork()) {
420			case 0: /* child */
421				(void)close(fdout[0]);
422				if (swrite(fdin[1], old, n) != (ssize_t)n) {
423#ifdef DEBUG
424					(void)fprintf(stderr,
425					    "Write failed (%s)\n",
426					    strerror(errno));
427#endif
428					exit(1);
429				}
430				exit(0);
431				/*NOTREACHED*/
432
433			case -1:
434#ifdef DEBUG
435				(void)fprintf(stderr, "Fork failed (%s)\n",
436				    strerror(errno));
437#endif
438				exit(1);
439				/*NOTREACHED*/
440
441			default:  /* parent */
442				break;
443			}
444			(void) close(fdin[1]);
445			fdin[1] = -1;
446		}
447
448		if ((*newch = (unsigned char *) malloc(HOWMANY + 1)) == NULL) {
449#ifdef DEBUG
450			(void)fprintf(stderr, "Malloc failed (%s)\n",
451			    strerror(errno));
452#endif
453			n = 0;
454			goto err;
455		}
456		if ((r = sread(fdout[0], *newch, HOWMANY, 0)) <= 0) {
457#ifdef DEBUG
458			(void)fprintf(stderr, "Read failed (%s)\n",
459			    strerror(errno));
460#endif
461			free(*newch);
462			n = 0;
463			newch[0] = '\0';
464			goto err;
465		} else {
466			n = r;
467		}
468 		/* NUL terminate, as every buffer is handled here. */
469 		(*newch)[n] = '\0';
470err:
471		if (fdin[1] != -1)
472			(void) close(fdin[1]);
473		(void) close(fdout[0]);
474#ifdef WNOHANG
475		while (waitpid(-1, NULL, WNOHANG) != -1)
476			continue;
477#else
478		(void)wait(NULL);
479#endif
480		return n;
481	}
482}
483