file/src/compress.c

/*
 * Copyright (c) Ian F. Darwin 1986-1995.
 * Software written by Ian F. Darwin and others;
 * maintained 1995-present by Christos Zoulas and others.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice immediately at the beginning of the file, without modification,
 *    this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *  
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * compress routines:
 *	zmagic() - returns 0 if not recognized, uncompresses and prints
 *		   information if recognized
 *	uncompress(method, old, n, newch) - uncompress old into new, 
 *					    using method, return sizeof new
 */
#include "file.h"

#ifndef lint
FILE_RCSID("@(#)$File: compress.c,v 1.101 2017/01/18 16:33:57 christos Exp $")
#endif

#include "magic.h"
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <stdarg.h>
#ifdef HAVE_SIGNAL_H
#include <signal.h>
# ifndef HAVE_SIG_T
typedef void (*sig_t)(int);
# endif /* HAVE_SIG_T */
#endif 
#if !defined(__MINGW32__) && !defined(WIN32)
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
#if defined(HAVE_SYS_TIME_H)
#include <sys/time.h>
#endif
#if defined(HAVE_ZLIB_H) && defined(ZLIBSUPPORT)
#define BUILTIN_DECOMPRESS
#include <zlib.h>
#endif
#ifdef DEBUG
int tty = -1;
#define DPRINTF(...)	do { \
	if (tty == -1) \
		tty = open("/dev/tty", O_RDWR); \
	if (tty == -1) \
		abort(); \
	dprintf(tty, __VA_ARGS__); \
} while (/*CONSTCOND*/0)
#else
#define DPRINTF(...)
#endif

#ifdef ZLIBSUPPORT
/*
 * The following python code is not really used because ZLIBSUPPORT is only
 * defined if we have a built-in zlib, and the built-in zlib handles that.
 * That is not true for android where we have zlib.h and not -lz.
 */
static const char zlibcode[] =
    "import sys, zlib; sys.stdout.write(zlib.decompress(sys.stdin.read()))";

static const char *zlib_args[] = { "python", "-c", zlibcode, NULL };

static int
zlibcmp(const unsigned char *buf)
{
	unsigned short x = 1;
	unsigned char *s = (unsigned char *)&x;

	if ((buf[0] & 0xf) != 8 || (buf[0] & 0x80) != 0)
		return 0;
	if (s[0] != 1)	/* endianness test */
		x = buf[0] | (buf[1] << 8);
	else
		x = buf[1] | (buf[0] << 8);
	if (x % 31)
		return 0;
	return 1;
}
#endif

#define gzip_flags "-cd"
#define lrzip_flags "-do"
#define lzip_flags gzip_flags

static const char *gzip_args[] = {
	"gzip", gzip_flags, NULL
};
static const char *uncompress_args[] = {
	"uncompress", "-c", NULL
};
static const char *bzip2_args[] = {
	"bzip2", "-cd", NULL
};
static const char *lzip_args[] = {
	"lzip", lzip_flags, NULL
};
static const char *xz_args[] = {
	"xz", "-cd", NULL
};
static const char *lrzip_args[] = {
	"lrzip", lrzip_flags, NULL
};
static const char *lz4_args[] = {
	"lz4", "-cd", NULL
};
static const char *zstd_args[] = {
	"zstd", "-cd", NULL
};

private const struct {
	const void *magic;
	size_t maglen;
	const char **argv;
} compr[] = {
	{ "\037\235",	2, gzip_args },		/* compressed */
	/* Uncompress can get stuck; so use gzip first if we have it
	 * Idea from Damien Clark, thanks! */
	{ "\037\235",	2, uncompress_args },	/* compressed */
	{ "\037\213",	2, gzip_args },		/* gzipped */
	{ "\037\236",	2, gzip_args },		/* frozen */
	{ "\037\240",	2, gzip_args },		/* SCO LZH */
	/* the standard pack utilities do not accept standard input */
	{ "\037\036",	2, gzip_args },		/* packed */
	{ "PK\3\4",	4, gzip_args },		/* pkzipped, */
	/* ...only first file examined */
	{ "BZh",	3, bzip2_args },	/* bzip2-ed */
	{ "LZIP",	4, lzip_args },		/* lzip-ed */
 	{ "\3757zXZ\0",	6, xz_args },		/* XZ Utils */
 	{ "LRZI",	4, lrzip_args },	/* LRZIP */
 	{ "\004\"M\030",4, lz4_args },		/* LZ4 */
 	{ "\x28\xB5\x2F\xFD", 4, zstd_args },	/* zstd */
#ifdef ZLIBSUPPORT
	{ RCAST(const void *, zlibcmp),	0, zlib_args },		/* zlib */
#endif
};

#define OKDATA 	0
#define NODATA	1
#define ERRDATA	2

private ssize_t swrite(int, const void *, size_t);
#if HAVE_FORK
private size_t ncompr = sizeof(compr) / sizeof(compr[0]);
private int uncompressbuf(int, size_t, size_t, const unsigned char *,
    unsigned char **, size_t *);
#ifdef BUILTIN_DECOMPRESS
private int uncompresszlib(const unsigned char *, unsigned char **, size_t,
    size_t *, int);
private int uncompressgzipped(const unsigned char *, unsigned char **, size_t,
    size_t *);
#endif
static int makeerror(unsigned char **, size_t *, const char *, ...)
    __attribute__((__format__(__printf__, 3, 4)));
private const char *methodname(size_t);

protected int
file_zmagic(struct magic_set *ms, int fd, const char *name,
    const unsigned char *buf, size_t nbytes)
{
	unsigned char *newbuf = NULL;
	size_t i, nsz;
	char *rbuf;
	file_pushbuf_t *pb;
	int urv, prv, rv = 0;
	int mime = ms->flags & MAGIC_MIME;
#ifdef HAVE_SIGNAL_H
	sig_t osigpipe;
#endif

	if ((ms->flags & MAGIC_COMPRESS) == 0)
		return 0;

#ifdef HAVE_SIGNAL_H
	osigpipe = signal(SIGPIPE, SIG_IGN);
#endif
	for (i = 0; i < ncompr; i++) {
		int zm;
		if (nbytes < compr[i].maglen)
			continue;
#ifdef ZLIBSUPPORT
		if (compr[i].maglen == 0)
			zm = (RCAST(int (*)(const unsigned char *),
			    CCAST(void *, compr[i].magic)))(buf);
		else
#endif
			zm = memcmp(buf, compr[i].magic, compr[i].maglen) == 0;

		if (!zm)
			continue;
		nsz = nbytes;
		urv = uncompressbuf(fd, ms->bytes_max, i, buf, &newbuf, &nsz);
		DPRINTF("uncompressbuf = %d, %s, %zu\n", urv, (char *)newbuf,
		    nsz);
		switch (urv) {
		case OKDATA:
		case ERRDATA:
			
			ms->flags &= ~MAGIC_COMPRESS;
			if (urv == ERRDATA)
				prv = file_printf(ms, "%s ERROR: %s",
				    methodname(i), newbuf);
			else
				prv = file_buffer(ms, -1, name, newbuf, nsz);
			if (prv == -1)
				goto error;
			rv = 1;
			if ((ms->flags & MAGIC_COMPRESS_TRANSP) != 0)
				goto out;
			if (mime != MAGIC_MIME && mime != 0)
				goto out;
			if ((file_printf(ms,
			    mime ? " compressed-encoding=" : " (")) == -1)
				goto error;
			if ((pb = file_push_buffer(ms)) == NULL)
				goto error;
			/*
			 * XXX: If file_buffer fails here, we overwrite
			 * the compressed text. FIXME.
			 */
			if (file_buffer(ms, -1, NULL, buf, nbytes) == -1)
				goto error;
			if ((rbuf = file_pop_buffer(ms, pb)) != NULL) {
				if (file_printf(ms, "%s", rbuf) == -1) {
					free(rbuf);
					goto error;
				}
				free(rbuf);
			}
			if (!mime && file_printf(ms, ")") == -1)
				goto error;
			/*FALLTHROUGH*/
		case NODATA:
			break;
		default:
			abort();
			/*NOTREACHED*/
		error:
			rv = -1;
			break;
		}
	}
out:
	DPRINTF("rv = %d\n", rv);

#ifdef HAVE_SIGNAL_H
	(void)signal(SIGPIPE, osigpipe);
#endif
	free(newbuf);
	ms->flags |= MAGIC_COMPRESS;
	DPRINTF("Zmagic returns %d\n", rv);
	return rv;
}
#endif
/*
 * `safe' write for sockets and pipes.
 */
private ssize_t
swrite(int fd, const void *buf, size_t n)
{
	ssize_t rv;
	size_t rn = n;

	do
		switch (rv = write(fd, buf, n)) {
		case -1:
			if (errno == EINTR)
				continue;
			return -1;
		default:
			n -= rv;
			buf = CAST(const char *, buf) + rv;
			break;
		}
	while (n > 0);
	return rn;
}


/*
 * `safe' read for sockets and pipes.
 */
protected ssize_t
sread(int fd, void *buf, size_t n, int canbepipe __attribute__((__unused__)))
{
	ssize_t rv;
#ifdef FIONREAD
	int t = 0;
#endif
	size_t rn = n;

	if (fd == STDIN_FILENO)
		goto nocheck;

#ifdef FIONREAD
	if (canbepipe && (ioctl(fd, FIONREAD, &t) == -1 || t == 0)) {
#ifdef FD_ZERO
		ssize_t cnt;
		for (cnt = 0;; cnt++) {
			fd_set check;
			struct timeval tout = {0, 100 * 1000};
			int selrv;

			FD_ZERO(&check);
			FD_SET(fd, &check);

			/*
			 * Avoid soft deadlock: do not read if there
			 * is nothing to read from sockets and pipes.
			 */
			selrv = select(fd + 1, &check, NULL, NULL, &tout);
			if (selrv == -1) {
				if (errno == EINTR || errno == EAGAIN)
					continue;
			} else if (selrv == 0 && cnt >= 5) {
				return 0;
			} else
				break;
		}
#endif
		(void)ioctl(fd, FIONREAD, &t);
	}

	if (t > 0 && (size_t)t < n) {
		n = t;
		rn = n;
	}
#endif

nocheck:
	do
		switch ((rv = read(fd, buf, n))) {
		case -1:
			if (errno == EINTR)
				continue;
			return -1;
		case 0:
			return rn - n;
		default:
			n -= rv;
			buf = CAST(char *, CCAST(void *, buf)) + rv;
			break;
		}
	while (n > 0);
	return rn;
}

protected int
file_pipe2file(struct magic_set *ms, int fd, const void *startbuf,
    size_t nbytes)
{
	char buf[4096];
	ssize_t r;
	int tfd;

	(void)strlcpy(buf, "/tmp/file.XXXXXX", sizeof buf);
#ifndef HAVE_MKSTEMP
	{
		char *ptr = mktemp(buf);
		tfd = open(ptr, O_RDWR|O_TRUNC|O_EXCL|O_CREAT, 0600);
		r = errno;
		(void)unlink(ptr);
		errno = r;
	}
#else
	{
		int te;
		tfd = mkstemp(buf);
		te = errno;
		(void)unlink(buf);
		errno = te;
	}
#endif
	if (tfd == -1) {
		file_error(ms, errno,
		    "cannot create temporary file for pipe copy");
		return -1;
	}

	if (swrite(tfd, startbuf, nbytes) != (ssize_t)nbytes)
		r = 1;
	else {
		while ((r = sread(fd, buf, sizeof(buf), 1)) > 0)
			if (swrite(tfd, buf, (size_t)r) != r)
				break;
	}

	switch (r) {
	case -1:
		file_error(ms, errno, "error copying from pipe to temp file");
		return -1;
	case 0:
		break;
	default:
		file_error(ms, errno, "error while writing to temp file");
		return -1;
	}

	/*
	 * We duplicate the file descriptor, because fclose on a
	 * tmpfile will delete the file, but any open descriptors
	 * can still access the phantom inode.
	 */
	if ((fd = dup2(tfd, fd)) == -1) {
		file_error(ms, errno, "could not dup descriptor for temp file");
		return -1;
	}
	(void)close(tfd);
	if (lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) {
		file_badseek(ms);
		return -1;
	}
	return fd;
}
#if HAVE_FORK
#ifdef BUILTIN_DECOMPRESS

#define FHCRC		(1 << 1)
#define FEXTRA		(1 << 2)
#define FNAME		(1 << 3)
#define FCOMMENT	(1 << 4)


private int
uncompressgzipped(const unsigned char *old, unsigned char **newch,
    size_t bytes_max, size_t *n)
{
	unsigned char flg = old[3];
	size_t data_start = 10;

	if (flg & FEXTRA) {
		if (data_start + 1 >= *n)
			goto err;
		data_start += 2 + old[data_start] + old[data_start + 1] * 256;
	}
	if (flg & FNAME) {
		while(data_start < *n && old[data_start])
			data_start++;
		data_start++;
	}
	if (flg & FCOMMENT) {
		while(data_start < *n && old[data_start])
			data_start++;
		data_start++;
	}
	if (flg & FHCRC)
		data_start += 2;

	if (data_start >= *n)
		goto err;

	*n -= data_start;
	old += data_start;
	return uncompresszlib(old, newch, bytes_max, n, 0);
err:
	return makeerror(newch, n, "File too short");
}

private int
uncompresszlib(const unsigned char *old, unsigned char **newch,
    size_t bytes_max, size_t *n, int zlib)
{
	int rc;
	z_stream z;

	if ((*newch = CAST(unsigned char *, malloc(bytes_max + 1))) == NULL) 
		return makeerror(newch, n, "No buffer, %s", strerror(errno));

	z.next_in = CCAST(Bytef *, old);
	z.avail_in = CAST(uint32_t, *n);
	z.next_out = *newch;
	z.avail_out = bytes_max;
	z.zalloc = Z_NULL;
	z.zfree = Z_NULL;
	z.opaque = Z_NULL;

	/* LINTED bug in header macro */
	rc = zlib ? inflateInit(&z) : inflateInit2(&z, -15);
	if (rc != Z_OK)
		goto err;

	rc = inflate(&z, Z_SYNC_FLUSH);
	if (rc != Z_OK && rc != Z_STREAM_END)
		goto err;

	*n = (size_t)z.total_out;
	rc = inflateEnd(&z);
	if (rc != Z_OK)
		goto err;
	
	/* let's keep the nul-terminate tradition */
	(*newch)[*n] = '\0';

	return OKDATA;
err:
	strlcpy((char *)*newch, z.msg ? z.msg : zError(rc), bytes_max);
	*n = strlen((char *)*newch);
	return ERRDATA;
}
#endif

static int
makeerror(unsigned char **buf, size_t *len, const char *fmt, ...)
{
	char *msg;
	va_list ap;
	int rv;

	va_start(ap, fmt);
	rv = vasprintf(&msg, fmt, ap);
	va_end(ap);
	if (rv < 0) {
		*buf = NULL;
		*len = 0;
		return NODATA;
	}
	*buf = (unsigned char *)msg;
	*len = strlen(msg);
	return ERRDATA;
}

static void
closefd(int *fd, size_t i)
{
	if (fd[i] == -1)
		return;
	(void) close(fd[i]);
	fd[i] = -1;
}

static void
closep(int *fd)
{
	size_t i;
	for (i = 0; i < 2; i++)
		closefd(fd, i);
}

static void
copydesc(int i, int *fd)
{
	int j = fd[i == STDIN_FILENO ? 0 : 1];
	if (j == i)
		return;
	if (dup2(j, i) == -1) {
		DPRINTF("dup(%d, %d) failed (%s)\n", j, i, strerror(errno));
		exit(1);
	}
	closep(fd);
}

static void
writechild(int fdp[3][2], const void *old, size_t n)
{
	int status;

	closefd(fdp[STDIN_FILENO], 0);
	/* 
	 * fork again, to avoid blocking because both
	 * pipes filled
	 */
	switch (fork()) {
	case 0: /* child */
		closefd(fdp[STDOUT_FILENO], 0);
		if (swrite(fdp[STDIN_FILENO][1], old, n) != (ssize_t)n) {
			DPRINTF("Write failed (%s)\n", strerror(errno));
			exit(1);
		}
		exit(0);
		/*NOTREACHED*/

	case -1:
		DPRINTF("Fork failed (%s)\n", strerror(errno));
		exit(1);
		/*NOTREACHED*/

	default:  /* parent */
		if (wait(&status) == -1) {
			DPRINTF("Wait failed (%s)\n", strerror(errno));
			exit(1);
		}
		DPRINTF("Grandchild wait return %#x\n", status);
	}
	closefd(fdp[STDIN_FILENO], 1);
}

static ssize_t
filter_error(unsigned char *ubuf, ssize_t n)
{
	char *p;
	char *buf;

	ubuf[n] = '\0';
	buf = (char *)ubuf;
	while (isspace((unsigned char)*buf))
		buf++;
	DPRINTF("Filter error[[[%s]]]\n", buf);
	if ((p = strchr((char *)buf, '\n')) != NULL)
		*p = '\0';
	if ((p = strchr((char *)buf, ';')) != NULL)
		*p = '\0';
	if ((p = strrchr((char *)buf, ':')) != NULL) {
		++p;
		while (isspace((unsigned char)*p))
			p++;
		n = strlen(p);
		memmove(ubuf, p, n + 1);
	}
	DPRINTF("Filter error after[[[%s]]]\n", (char *)ubuf);
	if (islower(*ubuf))
		*ubuf = toupper(*ubuf);
	return n;
}

private const char *
methodname(size_t method)
{
#ifdef BUILTIN_DECOMPRESS
        /* FIXME: This doesn't cope with bzip2 */
	if (method == 2 || compr[method].maglen == 0)
	    return "zlib";
#endif
	return compr[method].argv[0];
}

private int
uncompressbuf(int fd, size_t bytes_max, size_t method, const unsigned char *old,
    unsigned char **newch, size_t* n)
{
	int fdp[3][2];
	int status, rv;
	size_t i;
	ssize_t r;

#ifdef BUILTIN_DECOMPRESS
        /* FIXME: This doesn't cope with bzip2 */
	if (method == 2)
		return uncompressgzipped(old, newch, bytes_max, n);
	if (compr[method].maglen == 0)
		return uncompresszlib(old, newch, bytes_max, n, 1);
#endif
	(void)fflush(stdout);
	(void)fflush(stderr);

	for (i = 0; i < __arraycount(fdp); i++)
		fdp[i][0] = fdp[i][1] = -1;

	if ((fd == -1 && pipe(fdp[STDIN_FILENO]) == -1) ||
	    pipe(fdp[STDOUT_FILENO]) == -1 || pipe(fdp[STDERR_FILENO]) == -1) {
		closep(fdp[STDIN_FILENO]);
		closep(fdp[STDOUT_FILENO]);
		return makeerror(newch, n, "Cannot create pipe, %s",
		    strerror(errno));
	}
	switch (fork()) {
	case 0:	/* child */
		if (fd != -1) {
			fdp[STDIN_FILENO][0] = fd;
			(void) lseek(fd, (off_t)0, SEEK_SET);
		}
		
		for (i = 0; i < __arraycount(fdp); i++)
			copydesc(i, fdp[i]);

		(void)execvp(compr[method].argv[0],
		    (char *const *)(intptr_t)compr[method].argv);
		dprintf(STDERR_FILENO, "exec `%s' failed, %s", 
		    compr[method].argv[0], strerror(errno));
		exit(1);
		/*NOTREACHED*/
	case -1:
		return makeerror(newch, n, "Cannot fork, %s",
		    strerror(errno));

	default: /* parent */
		for (i = 1; i < __arraycount(fdp); i++)
			closefd(fdp[i], 1);

		/* Write the buffer data to the child, if we don't have fd */
		if (fd == -1)
			writechild(fdp, old, *n);

		*newch = CAST(unsigned char *, malloc(bytes_max + 1));
		if (*newch == NULL) {
			rv = makeerror(newch, n, "No buffer, %s",
			    strerror(errno));
			goto err;
		}
		rv = OKDATA;
		if ((r = sread(fdp[STDOUT_FILENO][0], *newch, bytes_max, 0)) > 0)
			break;
		DPRINTF("Read stdout failed %d (%s)\n", fdp[STDOUT_FILENO][0],
		    r != -1 ? strerror(errno) : "no data");

		rv = ERRDATA;
		if (r == 0 &&
		    (r = sread(fdp[STDERR_FILENO][0], *newch, bytes_max, 0)) > 0)
		{
			r = filter_error(*newch, r);
			break;
		}
		free(*newch);
		if  (r == 0)
			rv = makeerror(newch, n, "Read failed, %s",
			    strerror(errno));
		else
			rv = makeerror(newch, n, "No data");
		goto err;
	}

	*n = r;
	/* NUL terminate, as every buffer is handled here. */
	(*newch)[*n] = '\0';
err:
	closefd(fdp[STDIN_FILENO], 1);
	closefd(fdp[STDOUT_FILENO], 0);
	closefd(fdp[STDERR_FILENO], 0);
	if (wait(&status) == -1) {
		free(*newch);
		rv = makeerror(newch, n, "Wait failed, %s", strerror(errno));
		DPRINTF("Child wait return %#x\n", status);
	} else if (!WIFEXITED(status)) {
		DPRINTF("Child not exited (0x%x)\n", status);
	} else if (WEXITSTATUS(status) != 0) {
		DPRINTF("Child exited (0x%d)\n", WEXITSTATUS(status));
	}

	closefd(fdp[STDIN_FILENO], 0);
	DPRINTF("Returning %p n=%zu rv=%d\n", *newch, *n, rv);
    
	return rv;
}
#endif