archival/tar.c

/* vi: set sw=4 ts=4: */
/*
 * Mini tar implementation for busybox
 *
 * Modified to use common extraction code used by ar, cpio, dpkg-deb, dpkg
 *  by Glenn McGrath
 *
 * Note, that as of BusyBox-0.43, tar has been completely rewritten from the
 * ground up.  It still has remnants of the old code lying about, but it is
 * very different now (i.e., cleaner, less global variables, etc.)
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Based in part in the tar implementation in sash
 *  Copyright (c) 1999 by David I. Bell
 *  Permission is granted to use, distribute, or modify this source,
 *  provided that this copyright notice remains intact.
 *  Permission to distribute sash derived code under GPL has been granted.
 *
 * Based in part on the tar implementation from busybox-0.28
 *  Copyright (C) 1995 Bruce Perens
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config TAR
//config:	bool "tar (39 kb)"
//config:	default y
//config:	help
//config:	tar is an archiving program. It's commonly used with gzip to
//config:	create compressed archives. It's probably the most widely used
//config:	UNIX archive program.
//config:
//config:config FEATURE_TAR_LONG_OPTIONS
//config:	bool "Enable long options"
//config:	default y
//config:	depends on TAR && LONG_OPTS
//config:
//config:config FEATURE_TAR_CREATE
//config:	bool "Enable -c (archive creation)"
//config:	default y
//config:	depends on TAR
//config:
//config:config FEATURE_TAR_AUTODETECT
//config:	bool "Autodetect compressed tarballs"
//config:	default y
//config:	depends on TAR && (FEATURE_SEAMLESS_Z || FEATURE_SEAMLESS_GZ || FEATURE_SEAMLESS_BZ2 || FEATURE_SEAMLESS_LZMA || FEATURE_SEAMLESS_XZ)
//config:	help
//config:	With this option tar can automatically detect compressed
//config:	tarballs. Currently it works only on files (not pipes etc).
//config:
//config:config FEATURE_TAR_FROM
//config:	bool "Enable -X (exclude from) and -T (include from) options"
//config:	default y
//config:	depends on TAR
//config:	help
//config:	If you enable this option you'll be able to specify
//config:	a list of files to include or exclude from an archive.
//config:
//config:config FEATURE_TAR_OLDGNU_COMPATIBILITY
//config:	bool "Support old tar header format"
//config:	default y
//config:	depends on TAR || DPKG
//config:	help
//config:	This option is required to unpack archives created in
//config:	the old GNU format; help to kill this old format by
//config:	repacking your ancient archives with the new format.
//config:
//config:config FEATURE_TAR_OLDSUN_COMPATIBILITY
//config:	bool "Enable untarring of tarballs with checksums produced by buggy Sun tar"
//config:	default y
//config:	depends on TAR || DPKG
//config:	help
//config:	This option is required to unpack archives created by some old
//config:	version of Sun's tar (it was calculating checksum using signed
//config:	arithmetic). It is said to be fixed in newer Sun tar, but "old"
//config:	tarballs still exist.
//config:
//config:config FEATURE_TAR_GNU_EXTENSIONS
//config:	bool "Support GNU tar extensions (long filenames)"
//config:	default y
//config:	depends on TAR || DPKG
//config:
//config:config FEATURE_TAR_TO_COMMAND
//config:	bool "Support writing to an external program (--to-command)"
//config:	default y
//config:	depends on TAR && FEATURE_TAR_LONG_OPTIONS
//config:	help
//config:	If you enable this option you'll be able to instruct tar to send
//config:	the contents of each extracted file to the standard input of an
//config:	external program.
//config:
//config:config FEATURE_TAR_UNAME_GNAME
//config:	bool "Enable use of user and group names"
//config:	default y
//config:	depends on TAR
//config:	help
//config:	Enable use of user and group names in tar. This affects contents
//config:	listings (-t) and preserving permissions when unpacking (-p).
//config:	+200 bytes.
//config:
//config:config FEATURE_TAR_NOPRESERVE_TIME
//config:	bool "Enable -m (do not preserve time) GNU option"
//config:	default y
//config:	depends on TAR
//config:
//config:config FEATURE_TAR_SELINUX
//config:	bool "Support extracting SELinux labels"
//config:	default n
//config:	depends on TAR && SELINUX
//config:	help
//config:	With this option busybox supports restoring SELinux labels
//config:	when extracting files from tar archives.

//applet:IF_TAR(APPLET(tar, BB_DIR_BIN, BB_SUID_DROP))

//kbuild:lib-$(CONFIG_TAR) += tar.o

#include <fnmatch.h>
#include "libbb.h"
#include "common_bufsiz.h"
#include "bb_archive.h"
/* FIXME: Stop using this non-standard feature */
#ifndef FNM_LEADING_DIR
# define FNM_LEADING_DIR 0
#endif

#if 0
# define DBG(fmt, ...) bb_error_msg("%s: " fmt, __func__, ## __VA_ARGS__)
#else
# define DBG(...) ((void)0)
#endif
#define DBG_OPTION_PARSING 0


#define block_buf bb_common_bufsiz1
#define INIT_G() do { setup_common_bufsiz(); } while (0)


#if ENABLE_FEATURE_TAR_CREATE

/*
** writeTarFile(), writeFileToTarball(), and writeTarHeader() are
** the only functions that deal with the HardLinkInfo structure.
** Even these functions use the xxxHardLinkInfo() functions.
*/
typedef struct HardLinkInfo {
	struct HardLinkInfo *next; /* Next entry in list */
	dev_t dev;                 /* Device number */
	ino_t ino;                 /* Inode number */
//	short linkCount;           /* (Hard) Link Count */
	char name[1];              /* Start of filename (must be last) */
} HardLinkInfo;

/* Some info to be carried along when creating a new tarball */
typedef struct TarBallInfo {
	int tarFd;                      /* Open-for-write file descriptor
	                                 * for the tarball */
	int verboseFlag;                /* Whether to print extra stuff or not */
# if ENABLE_FEATURE_TAR_FROM
	const llist_t *excludeList;     /* List of files to not include */
# endif
	HardLinkInfo *hlInfoHead;       /* Hard Link Tracking Information */
	HardLinkInfo *hlInfo;           /* Hard Link Info for the current file */
//TODO: save only st_dev + st_ino
	struct stat tarFileStatBuf;     /* Stat info for the tarball, letting
	                                 * us know the inode and device that the
	                                 * tarball lives, so we can avoid trying
	                                 * to include the tarball into itself */
} TarBallInfo;

/* A nice enum with all the possible tar file content types */
enum {
	REGTYPE = '0',		/* regular file */
	REGTYPE0 = '\0',	/* regular file (ancient bug compat) */
	LNKTYPE = '1',		/* hard link */
	SYMTYPE = '2',		/* symbolic link */
	CHRTYPE = '3',		/* character special */
	BLKTYPE = '4',		/* block special */
	DIRTYPE = '5',		/* directory */
	FIFOTYPE = '6',		/* FIFO special */
	CONTTYPE = '7',		/* reserved */
	GNULONGLINK = 'K',	/* GNU long (>100 chars) link name */
	GNULONGNAME = 'L',	/* GNU long (>100 chars) file name */
};

/* Might be faster (and bigger) if the dev/ino were stored in numeric order;) */
static void addHardLinkInfo(HardLinkInfo **hlInfoHeadPtr,
					struct stat *statbuf,
					const char *fileName)
{
	/* Note: hlInfoHeadPtr can never be NULL! */
	HardLinkInfo *hlInfo;

	hlInfo = xmalloc(sizeof(HardLinkInfo) + strlen(fileName));
	hlInfo->next = *hlInfoHeadPtr;
	*hlInfoHeadPtr = hlInfo;
	hlInfo->dev = statbuf->st_dev;
	hlInfo->ino = statbuf->st_ino;
//	hlInfo->linkCount = statbuf->st_nlink;
	strcpy(hlInfo->name, fileName);
}

static void freeHardLinkInfo(HardLinkInfo **hlInfoHeadPtr)
{
	HardLinkInfo *hlInfo;
	HardLinkInfo *hlInfoNext;

	if (hlInfoHeadPtr) {
		hlInfo = *hlInfoHeadPtr;
		while (hlInfo) {
			hlInfoNext = hlInfo->next;
			free(hlInfo);
			hlInfo = hlInfoNext;
		}
		*hlInfoHeadPtr = NULL;
	}
}

/* Might be faster (and bigger) if the dev/ino were stored in numeric order ;) */
static HardLinkInfo *findHardLinkInfo(HardLinkInfo *hlInfo, struct stat *statbuf)
{
	while (hlInfo) {
		if (statbuf->st_ino == hlInfo->ino
		 && statbuf->st_dev == hlInfo->dev
		) {
			DBG("found hardlink:'%s'", hlInfo->name);
			break;
		}
		hlInfo = hlInfo->next;
	}
	return hlInfo;
}

/* Put an octal string into the specified buffer.
 * The number is zero padded and possibly NUL terminated.
 * Stores low-order bits only if whole value does not fit. */
static void putOctal(char *cp, int len, off_t value)
{
	char tempBuffer[sizeof(off_t)*3 + 1];
	char *tempString = tempBuffer;
	int width;

	width = sprintf(tempBuffer, "%0*"OFF_FMT"o", len, value);
	tempString += (width - len);

	/* If string has leading zeroes, we can drop one */
	/* and field will have trailing '\0' */
	/* (increases chances of compat with other tars) */
	if (tempString[0] == '0')
		tempString++;

	/* Copy the string to the field */
	memcpy(cp, tempString, len);
}
#define PUT_OCTAL(a, b) putOctal((a), sizeof(a), (b))

static void chksum_and_xwrite(int fd, struct tar_header_t* hp)
{
	/* POSIX says that checksum is done on unsigned bytes
	 * (Sun and HP-UX gets it wrong... more details in
	 * GNU tar source) */
	const unsigned char *cp;
	int chksum, size;

	strcpy(hp->magic, "ustar  ");

	/* Calculate and store the checksum (i.e., the sum of all of the bytes of
	 * the header).  The checksum field must be filled with blanks for the
	 * calculation.  The checksum field is formatted differently from the
	 * other fields: it has 6 digits, a null, then a space -- rather than
	 * digits, followed by a null like the other fields... */
	memset(hp->chksum, ' ', sizeof(hp->chksum));
	cp = (const unsigned char *) hp;
	chksum = 0;
	size = sizeof(*hp);
	do { chksum += *cp++; } while (--size);
	putOctal(hp->chksum, sizeof(hp->chksum)-1, chksum);

	/* Now write the header out to disk */
	xwrite(fd, hp, sizeof(*hp));
}

# if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
static void writeLongname(int fd, int type, const char *name, int dir)
{
	struct prefilled {
		char mode[8];             /* 100-107 */
		char uid[8];              /* 108-115 */
		char gid[8];              /* 116-123 */
		char size[12];            /* 124-135 */
		char mtime[12];           /* 136-147 */
	};
	struct tar_header_t header;
	int size;

	memset(&header, 0, sizeof(header));
	header.typeflag = type;
	strcpy(header.name, "././@LongLink");
	/* This sets mode/uid/gid/mtime to "00...00<NUL>" strings */
	memset((char*)&header + offsetof(struct tar_header_t, mode), /* make gcc-9.x happy */
			'0', sizeof(struct prefilled));
	header.mode [sizeof(header.mode ) - 1] = '\0';
	header.uid  [sizeof(header.uid  ) - 1] = '\0';
	header.gid  [sizeof(header.gid  ) - 1] = '\0';
	/* header.size is filled by '0' now, will be corrected below */
	header.mtime[sizeof(header.mtime) - 1] = '\0';

	dir = !!dir; /* normalize: 0/1 */
	size = strlen(name) + 1 + dir; /* GNU tar uses strlen+1 */
	/* + dir: account for possible '/' */

	PUT_OCTAL(header.size, size);
	chksum_and_xwrite(fd, &header);

	/* Write filename[/] and pad the block. */
	/* dir=0: writes 'name<NUL>', pads */
	/* dir=1: writes 'name', writes '/<NUL>', pads */
	dir *= 2;
	xwrite(fd, name, size - dir);
	xwrite(fd, "/", dir);
	size = (-size) & (TAR_BLOCK_SIZE-1);
	memset(&header, 0, size);
	xwrite(fd, &header, size);
}
# endif

/* Write out a tar header for the specified file/directory/whatever */
static int writeTarHeader(struct TarBallInfo *tbInfo,
		const char *header_name, const char *fileName, struct stat *statbuf)
{
	struct tar_header_t header;

	memset(&header, 0, sizeof(header));

	strncpy(header.name, header_name, sizeof(header.name));

	/* POSIX says to mask mode with 07777. */
	PUT_OCTAL(header.mode, statbuf->st_mode & 07777);
	PUT_OCTAL(header.uid, statbuf->st_uid);
	PUT_OCTAL(header.gid, statbuf->st_gid);
	memset(header.size, '0', sizeof(header.size)-1); /* Regular file size is handled later */
	/* users report that files with negative st_mtime cause trouble, so: */
	PUT_OCTAL(header.mtime, statbuf->st_mtime >= 0 ? statbuf->st_mtime : 0);

	/* Enter the user and group names */
	safe_strncpy(header.uname, get_cached_username(statbuf->st_uid), sizeof(header.uname));
	safe_strncpy(header.gname, get_cached_groupname(statbuf->st_gid), sizeof(header.gname));

	if (tbInfo->hlInfo) {
		/* This is a hard link */
		header.typeflag = LNKTYPE;
		strncpy(header.linkname, tbInfo->hlInfo->name,
				sizeof(header.linkname));
# if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
		/* Write out long linkname if needed */
		if (header.linkname[sizeof(header.linkname)-1])
			writeLongname(tbInfo->tarFd, GNULONGLINK,
					tbInfo->hlInfo->name, 0);
# endif
	} else if (S_ISLNK(statbuf->st_mode)) {
		char *lpath = xmalloc_readlink_or_warn(fileName);
		if (!lpath)
			return FALSE;
		header.typeflag = SYMTYPE;
		strncpy(header.linkname, lpath, sizeof(header.linkname));
# if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
		/* Write out long linkname if needed */
		if (header.linkname[sizeof(header.linkname)-1])
			writeLongname(tbInfo->tarFd, GNULONGLINK, lpath, 0);
# else
		/* If it is larger than 100 bytes, bail out */
		if (header.linkname[sizeof(header.linkname)-1]) {
			free(lpath);
			bb_simple_error_msg("names longer than "NAME_SIZE_STR" chars not supported");
			return FALSE;
		}
# endif
		free(lpath);
	} else if (S_ISDIR(statbuf->st_mode)) {
		header.typeflag = DIRTYPE;
		/* Append '/' only if there is a space for it */
		if (!header.name[sizeof(header.name)-1])
			header.name[strlen(header.name)] = '/';
	} else if (S_ISCHR(statbuf->st_mode)) {
		header.typeflag = CHRTYPE;
		PUT_OCTAL(header.devmajor, major(statbuf->st_rdev));
		PUT_OCTAL(header.devminor, minor(statbuf->st_rdev));
	} else if (S_ISBLK(statbuf->st_mode)) {
		header.typeflag = BLKTYPE;
		PUT_OCTAL(header.devmajor, major(statbuf->st_rdev));
		PUT_OCTAL(header.devminor, minor(statbuf->st_rdev));
	} else if (S_ISFIFO(statbuf->st_mode)) {
		header.typeflag = FIFOTYPE;
	} else if (S_ISREG(statbuf->st_mode)) {
		/* header.size field is 12 bytes long */
		/* Does octal-encoded size fit? */
		uoff_t filesize = statbuf->st_size;
		if (sizeof(filesize) <= 4
		 || filesize <= (uoff_t)0777777777777LL
		) {
			PUT_OCTAL(header.size, filesize);
		}
		/* Does base256-encoded size fit?
		 * It always does unless off_t is wider than 64 bits.
		 */
		else if (ENABLE_FEATURE_TAR_GNU_EXTENSIONS
# if ULLONG_MAX > 0xffffffffffffffffLL /* 2^64-1 */
		 && (filesize <= 0x3fffffffffffffffffffffffLL)
# endif
		) {
			/* GNU tar uses "base-256 encoding" for very large numbers.
			 * Encoding is binary, with highest bit always set as a marker
			 * and sign in next-highest bit:
			 * 80 00 .. 00 - zero
			 * bf ff .. ff - largest positive number
			 * ff ff .. ff - minus 1
			 * c0 00 .. 00 - smallest negative number
			 */
			char *p8 = header.size + sizeof(header.size);
			do {
				*--p8 = (uint8_t)filesize;
				filesize >>= 8;
			} while (p8 != header.size);
			*p8 |= 0x80;
		} else {
			bb_error_msg_and_die("can't store file '%s' "
				"of size %"OFF_FMT"u, aborting",
				fileName, statbuf->st_size);
		}
		header.typeflag = REGTYPE;
	} else {
		bb_error_msg("%s: unknown file type", fileName);
		return FALSE;
	}

# if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	/* Write out long name if needed */
	/* (we, like GNU tar, output long linkname *before* long name) */
	if (header.name[sizeof(header.name)-1])
		writeLongname(tbInfo->tarFd, GNULONGNAME,
				header_name, S_ISDIR(statbuf->st_mode));
# endif

	/* Now write the header out to disk */
	chksum_and_xwrite(tbInfo->tarFd, &header);

	/* Now do the verbose thing (or not) */
	if (tbInfo->verboseFlag) {
		FILE *vbFd = stdout;

		/* If archive goes to stdout, verbose goes to stderr */
		if (tbInfo->tarFd == STDOUT_FILENO)
			vbFd = stderr;
		/* GNU "tar cvvf" prints "extended" listing a-la "ls -l" */
		/* We don't have such excesses here: for us "v" == "vv" */
		/* '/' is probably a GNUism */
		fprintf(vbFd, "%s%s\n", header_name,
				S_ISDIR(statbuf->st_mode) ? "/" : "");
	}

	return TRUE;
}

# if ENABLE_FEATURE_TAR_FROM
static int exclude_file(const llist_t *excluded_files, const char *file)
{
	while (excluded_files) {
		if (excluded_files->data[0] == '/') {
			if (fnmatch(excluded_files->data, file,
					FNM_PATHNAME | FNM_LEADING_DIR) == 0)
				return 1;
		} else {
			const char *p;

			for (p = file; p[0] != '\0'; p++) {
				if ((p == file || p[-1] == '/')
				 && p[0] != '/'
				 && fnmatch(excluded_files->data, p,
						FNM_PATHNAME | FNM_LEADING_DIR) == 0
				) {
					return 1;
				}
			}
		}
		excluded_files = excluded_files->link;
	}

	return 0;
}
# else
#  define exclude_file(excluded_files, file) 0
# endif

static int FAST_FUNC writeFileToTarball(struct recursive_state *state,
		const char *fileName,
		struct stat *statbuf)
{
	struct TarBallInfo *tbInfo = (struct TarBallInfo *) state->userData;
	const char *header_name;
	int inputFileFd = -1;

	DBG("writeFileToTarball('%s')", fileName);

	/* Strip leading '/' and such (must be before memorizing hardlink's name) */
	header_name = strip_unsafe_prefix(fileName);

	if (header_name[0] == '\0')
		return TRUE;

	if (exclude_file(tbInfo->excludeList, header_name))
		return SKIP; /* "do not recurse on this directory", no error message printed */

	/* It is against the rules to archive a socket */
	if (S_ISSOCK(statbuf->st_mode)) {
		bb_error_msg("%s: socket ignored", fileName);
		return TRUE;
	}

	/*
	 * Check to see if we are dealing with a hard link.
	 * If so -
	 * Treat the first occurrence of a given dev/inode as a file while
	 * treating any additional occurrences as hard links.  This is done
	 * by adding the file information to the HardLinkInfo linked list.
	 */
	tbInfo->hlInfo = NULL;
	if (!S_ISDIR(statbuf->st_mode) && statbuf->st_nlink > 1) {
		DBG("'%s': st_nlink > 1", header_name);
		tbInfo->hlInfo = findHardLinkInfo(tbInfo->hlInfoHead, statbuf);
		if (tbInfo->hlInfo == NULL) {
			DBG("'%s': addHardLinkInfo", header_name);
			addHardLinkInfo(&tbInfo->hlInfoHead, statbuf, header_name);
		}
	}

	/* It is a bad idea to store the archive we are in the process of creating,
	 * so check the device and inode to be sure that this particular file isn't
	 * the new tarball */
	if (tbInfo->tarFileStatBuf.st_dev == statbuf->st_dev
	 && tbInfo->tarFileStatBuf.st_ino == statbuf->st_ino
	) {
		bb_error_msg("%s: file is the archive; skipping", fileName);
		return TRUE;
	}

# if !ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	if (strlen(header_name) >= NAME_SIZE) {
		bb_simple_error_msg("names longer than "NAME_SIZE_STR" chars not supported");
		return TRUE;
	}
# endif

	/* Is this a regular file? */
	if (tbInfo->hlInfo == NULL && S_ISREG(statbuf->st_mode)) {
		/* open the file we want to archive, and make sure all is well */
		inputFileFd = open_or_warn(fileName, O_RDONLY);
		if (inputFileFd < 0) {
			return FALSE; /* make recursive_action() return FALSE */
		}
	}

	/* Add an entry to the tarball */
	if (writeTarHeader(tbInfo, header_name, fileName, statbuf) == FALSE) {
		return FALSE; /* make recursive_action() return FALSE */
	}

	/* If it was a regular file, write out the body */
	if (inputFileFd >= 0) {
		size_t readSize;
		/* Write the file to the archive. */
		/* We record size into header first, */
		/* and then write out file. If file shrinks in between, */
		/* tar will be corrupted. So we don't allow for that. */
		/* NB: GNU tar 1.16 warns and pads with zeroes */
		/* or even seeks back and updates header */
		bb_copyfd_exact_size(inputFileFd, tbInfo->tarFd, statbuf->st_size);
		////off_t readSize;
		////readSize = bb_copyfd_size(inputFileFd, tbInfo->tarFd, statbuf->st_size);
		////if (readSize != statbuf->st_size && readSize >= 0) {
		////	bb_error_msg_and_die("short read from %s, aborting", fileName);
		////}

		/* Check that file did not grow in between? */
		/* if (safe_read(inputFileFd, 1) == 1) warn but continue? */

		close(inputFileFd);

		/* Pad the file up to the tar block size */
		/* (a few tricks here in the name of code size) */
		readSize = (-(int)statbuf->st_size) & (TAR_BLOCK_SIZE-1);
		memset(block_buf, 0, readSize);
		xwrite(tbInfo->tarFd, block_buf, readSize);
	}

	return TRUE;
}

# if SEAMLESS_COMPRESSION
/* Don't inline: vfork scares gcc and pessimizes code */
static void NOINLINE vfork_compressor(int tar_fd, const char *gzip)
{
	// On Linux, vfork never unpauses parent early, although standard
	// allows for that. Do we want to waste bytes checking for it?
#  define WAIT_FOR_CHILD 0
	volatile int vfork_exec_errno = 0;
	struct fd_pair data;
#  if WAIT_FOR_CHILD
	struct fd_pair status;
	xpiped_pair(status);
#  endif
	xpiped_pair(data);

	signal(SIGPIPE, SIG_IGN); /* we only want EPIPE on errors */

	if (xvfork() == 0) {
		/* child */
		int tfd;
		/* NB: close _first_, then move fds! */
		close(data.wr);
#  if WAIT_FOR_CHILD
		close(status.rd);
		/* status.wr will close only on exec -
		 * parent waits for this close to happen */
		fcntl(status.wr, F_SETFD, FD_CLOEXEC);
#  endif
		/* copy it: parent's tar_fd variable must not change */
		tfd = tar_fd;
		if (tfd == 0) {
			/* Output tar fd may be zero.
			 * xmove_fd(data.rd, 0) would destroy it.
			 * Reproducer:
			 *  exec 0>&-
			 *  exec 1>&-
			 *  tar czf Z.tar.gz FILE
			 * Swapping move_fd's order wouldn't work:
			 * data.rd is 1 and _it_ would be destroyed.
			 */
			tfd = dup(tfd);
		}
		xmove_fd(data.rd, 0);
		xmove_fd(tfd, 1);

		/* exec gzip/bzip2/... program */
		//BB_EXECLP(gzip, gzip, "-f", (char *)0); - WRONG for "xz",
		// if xz is an enabled applet, it'll be a version which
		// can only decompress. We do need to execute external
		// program, not applet.
		execlp(gzip, gzip, "-f", (char *)0);

		vfork_exec_errno = errno;
		_exit(EXIT_FAILURE);
	}

	/* parent */
	xmove_fd(data.wr, tar_fd);
	close(data.rd);
#  if WAIT_FOR_CHILD
	close(status.wr);
	while (1) {
		/* Wait until child execs (or fails to) */
		char buf;
		int n = full_read(status.rd, &buf, 1);
		if (n < 0 /* && errno == EAGAIN */)
			continue;	/* try it again */
	}
	close(status.rd);
#  endif
	if (vfork_exec_errno) {
		errno = vfork_exec_errno;
		bb_perror_msg_and_die("can't execute '%s'", gzip);
	}
}
# endif /* SEAMLESS_COMPRESSION */


# if !SEAMLESS_COMPRESSION
/* Do not pass gzip flag to writeTarFile() */
#define writeTarFile(tbInfo, recurseFlags, filelist, gzip) \
	writeTarFile(tbInfo, recurseFlags, filelist)
# endif
/* gcc 4.2.1 inlines it, making code bigger */
static NOINLINE int writeTarFile(
	struct TarBallInfo *tbInfo,
	int recurseFlags,
	const llist_t *filelist,
	const char *gzip)
{
	int errorFlag = FALSE;

	/*tbInfo->hlInfoHead = NULL; - already is */

	/* Store the stat info for the tarball's file, so
	 * can avoid including the tarball into itself....  */
	xfstat(tbInfo->tarFd, &tbInfo->tarFileStatBuf, "can't stat tar file");

# if SEAMLESS_COMPRESSION
	if (gzip)
		vfork_compressor(tbInfo->tarFd, gzip);
# endif

	/* Read the directory/files and iterate over them one at a time */
	while (filelist) {
		if (!recursive_action(filelist->data, recurseFlags,
				writeFileToTarball, writeFileToTarball, tbInfo)
		) {
			errorFlag = TRUE;
		}
		filelist = filelist->link;
	}
	/* Write two empty blocks to the end of the archive */
	memset(block_buf, 0, 2*TAR_BLOCK_SIZE);
	xwrite(tbInfo->tarFd, block_buf, 2*TAR_BLOCK_SIZE);

	/* To be pedantically correct, we would check if the tarball
	 * is smaller than 20 tar blocks, and pad it if it was smaller,
	 * but that isn't necessary for GNU tar interoperability, and
	 * so is considered a waste of space */

	/* Close so the child process (if any) will exit */
	close(tbInfo->tarFd);

	/* Hang up the tools, close up shop, head home */
	if (ENABLE_FEATURE_CLEAN_UP)
		freeHardLinkInfo(&tbInfo->hlInfoHead);

	if (errorFlag)
		bb_simple_error_msg("error exit delayed from previous errors");

# if SEAMLESS_COMPRESSION
	if (gzip) {
		int status;
		if (safe_waitpid(-1, &status, 0) == -1)
			bb_simple_perror_msg("waitpid");
		else if (!WIFEXITED(status) || WEXITSTATUS(status))
			/* gzip was killed or has exited with nonzero! */
			errorFlag = TRUE;
	}
# endif
	return errorFlag;
}

#endif /* FEATURE_TAR_CREATE */

#if ENABLE_FEATURE_TAR_FROM
static llist_t *append_file_list_to_list(llist_t *list)
{
	llist_t *newlist = NULL;

	while (list) {
		FILE *src_stream;
		char *line;

		src_stream = xfopen_stdin(llist_pop(&list));
		while ((line = xmalloc_fgetline(src_stream)) != NULL) {
			/* kill trailing '/' unless the string is just "/" */
			char *cp = last_char_is(line, '/');
			if (cp > line)
				*cp = '\0';
			llist_add_to_end(&newlist, line);
		}
		fclose(src_stream);
	}
	return newlist;
}
#endif

//usage:#define tar_trivial_usage
//usage:	IF_FEATURE_TAR_CREATE("c|") "x|t [-"
//usage:	IF_FEATURE_SEAMLESS_Z("Z")
//usage:	IF_FEATURE_SEAMLESS_GZ("z")
//usage:	IF_FEATURE_SEAMLESS_XZ("J")
//usage:	IF_FEATURE_SEAMLESS_BZ2("j")
//usage:	"a"
//usage:	IF_FEATURE_TAR_CREATE("h")
//usage:	IF_FEATURE_TAR_NOPRESERVE_TIME("m")
//usage:	"vokO] "
//usage:	"[-f TARFILE] [-C DIR] "
//usage:	IF_FEATURE_TAR_FROM("[-T FILE] [-X FILE] "IF_FEATURE_TAR_LONG_OPTIONS("[LONGOPT]... "))
//usage:	"[FILE]..."
//usage:#define tar_full_usage "\n\n"
//usage:	IF_FEATURE_TAR_CREATE("Create, extract, ")
//usage:	IF_NOT_FEATURE_TAR_CREATE("Extract ")
//usage:	"or list files from a tar file"
//usage:     "\n"
//usage:	IF_FEATURE_TAR_CREATE(
//usage:     "\n	c	Create"
//usage:	)
//usage:     "\n	x	Extract"
//usage:     "\n	t	List"
//usage:     "\n	-f FILE	Name of TARFILE ('-' for stdin/out)"
//usage:     "\n	-C DIR	Change to DIR before operation"
//usage:     "\n	-v	Verbose"
//usage:     "\n	-O	Extract to stdout"
//usage:	IF_FEATURE_TAR_NOPRESERVE_TIME(
//usage:     "\n	-m	Don't restore mtime"
//usage:	)
//usage:     "\n	-o	Don't restore user:group"
///////:-p - accepted but ignored, restores mode (aliases in GNU tar: --preserve-permissions, --same-permissions)
//usage:     "\n	-k	Don't replace existing files"
//usage:	IF_FEATURE_SEAMLESS_Z(
//usage:     "\n	-Z	(De)compress using compress"
//usage:	)
//usage:	IF_FEATURE_SEAMLESS_GZ(
//usage:     "\n	-z	(De)compress using gzip"
//usage:	)
//usage:	IF_FEATURE_SEAMLESS_XZ(
//usage:     "\n	-J	(De)compress using xz"
//usage:	)
//usage:	IF_FEATURE_SEAMLESS_BZ2(
//usage:     "\n	-j	(De)compress using bzip2"
//usage:	)
//usage:	IF_FEATURE_SEAMLESS_LZMA(
//usage:	IF_FEATURE_TAR_LONG_OPTIONS(
//usage:     "\n	--lzma	(De)compress using lzma"
//usage:	)
//usage:	)
//usage:     "\n	-a	(De)compress based on extension"
//usage:	IF_FEATURE_TAR_CREATE(
//usage:     "\n	-h	Follow symlinks"
//usage:	)
//usage:	IF_FEATURE_TAR_FROM(
//usage:     "\n	-T FILE	File with names to include"
//usage:     "\n	-X FILE	File with glob patterns to exclude"
//usage:	IF_FEATURE_TAR_LONG_OPTIONS(
//usage:     "\n	--exclude PATTERN	Glob pattern to exclude"
//usage:	)
//usage:	)
//usage:	IF_FEATURE_TAR_LONG_OPTIONS(
//usage:     "\n	--overwrite		Replace existing files"
//usage:     "\n	--strip-components NUM	NUM of leading components to strip"
//usage:     "\n	--no-recursion		Don't descend in directories"
//usage:     "\n	--numeric-owner		Use numeric user:group"
//usage:     "\n	--no-same-permissions	Don't restore access permissions"
//usage:	IF_FEATURE_TAR_TO_COMMAND(
//usage:     "\n	--to-command COMMAND	Pipe files to COMMAND"
//usage:	)
//usage:	)
//usage:
//usage:#define tar_example_usage
//usage:       "$ zcat /tmp/tarball.tar.gz | tar -xf -\n"
//usage:       "$ tar -cf /tmp/tarball.tar /usr/local\n"

enum {
	OPTBIT_KEEP_OLD = 8,
	IF_FEATURE_TAR_CREATE(   OPTBIT_CREATE      ,)
	IF_FEATURE_TAR_CREATE(   OPTBIT_DEREFERENCE ,)
	IF_FEATURE_SEAMLESS_BZ2( OPTBIT_BZIP2       ,)
	IF_FEATURE_TAR_FROM(     OPTBIT_INCLUDE_FROM,)
	IF_FEATURE_TAR_FROM(     OPTBIT_EXCLUDE_FROM,)
	IF_FEATURE_SEAMLESS_GZ(  OPTBIT_GZIP        ,)
	IF_FEATURE_SEAMLESS_XZ(  OPTBIT_XZ          ,)
	IF_FEATURE_SEAMLESS_Z(   OPTBIT_COMPRESS    ,) // 16th bit
	OPTBIT_AUTOCOMPRESS_BY_EXT,
	IF_FEATURE_TAR_NOPRESERVE_TIME(OPTBIT_NOPRESERVE_TIME,)
#if ENABLE_FEATURE_TAR_LONG_OPTIONS
	OPTBIT_STRIP_COMPONENTS,
	IF_FEATURE_SEAMLESS_LZMA(OPTBIT_LZMA        ,)
	OPTBIT_NORECURSION,
	IF_FEATURE_TAR_TO_COMMAND(OPTBIT_2COMMAND   ,)
	OPTBIT_NUMERIC_OWNER,
	OPTBIT_NOPRESERVE_PERM,
	OPTBIT_OVERWRITE,
#endif
	OPT_TEST         = 1 << 0, // t
	OPT_EXTRACT      = 1 << 1, // x
	OPT_BASEDIR      = 1 << 2, // C
	OPT_TARNAME      = 1 << 3, // f
	OPT_2STDOUT      = 1 << 4, // O
	OPT_NOPRESERVE_OWNER = 1 << 5, // o == no-same-owner
	OPT_P            = 1 << 6, // p
	OPT_VERBOSE      = 1 << 7, // v
	OPT_KEEP_OLD     = 1 << 8, // k
	OPT_CREATE       = IF_FEATURE_TAR_CREATE(   (1 << OPTBIT_CREATE      )) + 0, // c
	OPT_DEREFERENCE  = IF_FEATURE_TAR_CREATE(   (1 << OPTBIT_DEREFERENCE )) + 0, // h
	OPT_BZIP2        = IF_FEATURE_SEAMLESS_BZ2( (1 << OPTBIT_BZIP2       )) + 0, // j
	OPT_INCLUDE_FROM = IF_FEATURE_TAR_FROM(     (1 << OPTBIT_INCLUDE_FROM)) + 0, // T
	OPT_EXCLUDE_FROM = IF_FEATURE_TAR_FROM(     (1 << OPTBIT_EXCLUDE_FROM)) + 0, // X
	OPT_GZIP         = IF_FEATURE_SEAMLESS_GZ(  (1 << OPTBIT_GZIP        )) + 0, // z
	OPT_XZ           = IF_FEATURE_SEAMLESS_XZ(  (1 << OPTBIT_XZ          )) + 0, // J
	OPT_COMPRESS     = IF_FEATURE_SEAMLESS_Z(   (1 << OPTBIT_COMPRESS    )) + 0, // Z
	OPT_AUTOCOMPRESS_BY_EXT = 1 << OPTBIT_AUTOCOMPRESS_BY_EXT,                   // a
	OPT_NOPRESERVE_TIME  = IF_FEATURE_TAR_NOPRESERVE_TIME((1 << OPTBIT_NOPRESERVE_TIME)) + 0, // m
	OPT_STRIP_COMPONENTS = IF_FEATURE_TAR_LONG_OPTIONS((1 << OPTBIT_STRIP_COMPONENTS)) + 0, // strip-components
	OPT_LZMA             = IF_FEATURE_TAR_LONG_OPTIONS(IF_FEATURE_SEAMLESS_LZMA((1 << OPTBIT_LZMA))) + 0, // lzma
	OPT_NORECURSION      = IF_FEATURE_TAR_LONG_OPTIONS((1 << OPTBIT_NORECURSION    )) + 0, // no-recursion
	OPT_2COMMAND         = IF_FEATURE_TAR_TO_COMMAND(  (1 << OPTBIT_2COMMAND       )) + 0, // to-command
	OPT_NUMERIC_OWNER    = IF_FEATURE_TAR_LONG_OPTIONS((1 << OPTBIT_NUMERIC_OWNER  )) + 0, // numeric-owner
	OPT_NOPRESERVE_PERM  = IF_FEATURE_TAR_LONG_OPTIONS((1 << OPTBIT_NOPRESERVE_PERM)) + 0, // no-same-permissions
	OPT_OVERWRITE        = IF_FEATURE_TAR_LONG_OPTIONS((1 << OPTBIT_OVERWRITE      )) + 0, // overwrite

	OPT_ANY_COMPRESS = (OPT_BZIP2 | OPT_LZMA | OPT_GZIP | OPT_XZ | OPT_COMPRESS),
};
#if ENABLE_FEATURE_TAR_LONG_OPTIONS
static const char tar_longopts[] ALIGN1 =
	"list\0"                No_argument       "t"
	"extract\0"             No_argument       "x"
	"directory\0"           Required_argument "C"
	"file\0"                Required_argument "f"
	"to-stdout\0"           No_argument       "O"
	/* do not restore owner */
	/* Note: GNU tar handles 'o' as no-same-owner only on extract,
	 * on create, 'o' is --old-archive. We do not support --old-archive. */
	"no-same-owner\0"       No_argument       "o"
	"same-permissions\0"    No_argument       "p"
	"verbose\0"             No_argument       "v"
	"keep-old\0"            No_argument       "k"
# if ENABLE_FEATURE_TAR_CREATE
	"create\0"              No_argument       "c"
	"dereference\0"         No_argument       "h"
# endif
# if ENABLE_FEATURE_SEAMLESS_BZ2
	"bzip2\0"               No_argument       "j"
# endif
# if ENABLE_FEATURE_TAR_FROM
	"files-from\0"          Required_argument "T"
	"exclude-from\0"        Required_argument "X"
# endif
# if ENABLE_FEATURE_SEAMLESS_GZ
	"gzip\0"                No_argument       "z"
# endif
# if ENABLE_FEATURE_SEAMLESS_XZ
	"xz\0"                  No_argument       "J"
# endif
# if ENABLE_FEATURE_SEAMLESS_Z
	"compress\0"            No_argument       "Z"
# endif
	"auto-compress\0"       No_argument       "a"
# if ENABLE_FEATURE_TAR_NOPRESERVE_TIME
	"touch\0"               No_argument       "m"
# endif
	"strip-components\0"	Required_argument "\xf8"
# if ENABLE_FEATURE_SEAMLESS_LZMA
	"lzma\0"                No_argument       "\xf9"
# endif
	"no-recursion\0"	No_argument       "\xfa"
# if ENABLE_FEATURE_TAR_TO_COMMAND
	"to-command\0"		Required_argument "\xfb"
# endif
	/* use numeric uid/gid from tar header, not textual */
	"numeric-owner\0"       No_argument       "\xfc"
	/* do not restore mode */
	"no-same-permissions\0" No_argument       "\xfd"
	/* on unpack, open with O_TRUNC and !O_EXCL */
	"overwrite\0"           No_argument       "\xfe"
	/* --exclude takes next bit position in option mask, */
	/* therefore we have to put it _after_ --no-same-permissions */
# if ENABLE_FEATURE_TAR_FROM
	"exclude\0"             Required_argument "\xff"
# endif
	;
# define GETOPT32 getopt32long
# define LONGOPTS ,tar_longopts
#else
# define GETOPT32 getopt32
# define LONGOPTS
#endif

int tar_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int tar_main(int argc UNUSED_PARAM, char **argv)
{
	archive_handle_t *tar_handle;
	char *base_dir = NULL;
	const char *tar_filename = "-";
	unsigned opt;
	int verboseFlag = 0;
#if ENABLE_FEATURE_TAR_LONG_OPTIONS && ENABLE_FEATURE_TAR_FROM
	llist_t *excludes = NULL;
#endif
	INIT_G();

	/* Initialise default values */
	tar_handle = init_handle();
	tar_handle->ah_flags = ARCHIVE_CREATE_LEADING_DIRS
	                     | ARCHIVE_RESTORE_DATE
	                     | ARCHIVE_UNLINK_OLD;

	/* Apparently only root's tar preserves perms (see bug 3844) */
	if (getuid() != 0)
		tar_handle->ah_flags |= ARCHIVE_DONT_RESTORE_PERM;

#if ENABLE_DESKTOP
	/* Lie to buildroot when it starts asking stupid questions. */
	if (argv[1] && strcmp(argv[1], "--version") == 0) {
		// Output of 'tar --version' examples:
		// tar (GNU tar) 1.15.1
		// tar (GNU tar) 1.25
		// bsdtar 2.8.3 - libarchive 2.8.3
		puts("tar (busybox) " BB_VER);
		return 0;
	}
#endif
	if (argv[1] && argv[1][0] != '-' && argv[1][0] != '\0') {
		/* Compat:
		 * 1st argument without dash handles options with parameters
		 * differently from dashed one: it takes *next argv[i]*
		 * as parameter even if there are more chars in 1st argument:
		 *  "tar fx TARFILE" - "x" is not taken as f's param
		 *  but is interpreted as -x option
		 *  "tar -xf TARFILE" - dashed equivalent of the above
		 *  "tar -fx ..." - "x" is taken as f's param
		 * getopt32 wouldn't handle 1st command correctly.
		 * Unfortunately, people do use such commands.
		 * We massage argv[1] to work around it by moving 'f'
		 * to the end of the string.
		 * More contrived "tar fCx TARFILE DIR" still fails,
		 * but such commands are much less likely to be used.
		 */
		char *f = strchr(argv[1], 'f');
		if (f) {
			while (f[1] != '\0') {
				*f = f[1];
				f++;
			}
			*f = 'f';
		}
		/* Prepend '-' to the first argument  */
		argv[1] = xasprintf("-%s", argv[1]);
	}
	opt = GETOPT32(argv, "^"
		"txC:f:Oopvk"
		IF_FEATURE_TAR_CREATE(   "ch"    )
		IF_FEATURE_SEAMLESS_BZ2( "j"     )
		IF_FEATURE_TAR_FROM(     "T:*X:*")
		IF_FEATURE_SEAMLESS_GZ(  "z"     )
		IF_FEATURE_SEAMLESS_XZ(  "J"     )
		IF_FEATURE_SEAMLESS_Z(   "Z"     )
		"a"
		IF_FEATURE_TAR_NOPRESERVE_TIME("m")
		IF_FEATURE_TAR_LONG_OPTIONS("\xf8:") // --strip-components
		"\0"
		"tt:vv:" // count -t,-v
#if ENABLE_FEATURE_TAR_LONG_OPTIONS && ENABLE_FEATURE_TAR_FROM
		"\xff::" // --exclude=PATTERN is a list
#endif
		IF_FEATURE_TAR_CREATE("c:") "t:x:" // at least one of these is reqd
		IF_FEATURE_TAR_CREATE("c--tx:t--cx:x--ct") // mutually exclusive
		IF_NOT_FEATURE_TAR_CREATE("t--x:x--t") // mutually exclusive
#if ENABLE_FEATURE_TAR_LONG_OPTIONS
		":\xf8+" // --strip-components=NUM
#endif
		LONGOPTS
		, &base_dir // -C dir
		, &tar_filename // -f filename
		IF_FEATURE_TAR_FROM(, &(tar_handle->accept)) // T
		IF_FEATURE_TAR_FROM(, &(tar_handle->reject)) // X
#if ENABLE_FEATURE_TAR_LONG_OPTIONS
		, &tar_handle->tar__strip_components // --strip-components
#endif
		IF_FEATURE_TAR_TO_COMMAND(, &(tar_handle->tar__to_command)) // --to-command
#if ENABLE_FEATURE_TAR_LONG_OPTIONS && ENABLE_FEATURE_TAR_FROM
		, &excludes // --exclude
#endif
		, &verboseFlag // combined count for -t and -v
		, &verboseFlag // combined count for -t and -v
		);
#if DBG_OPTION_PARSING
	bb_error_msg("opt: 0x%08x", opt);
# define showopt(o) bb_error_msg("opt & %s(%x):\t%x", #o, o, opt & o);
	showopt(OPT_TEST            );
	showopt(OPT_EXTRACT         );
	showopt(OPT_BASEDIR         );
	showopt(OPT_TARNAME         );
	showopt(OPT_2STDOUT         );
	showopt(OPT_NOPRESERVE_OWNER);
	showopt(OPT_P               );
	showopt(OPT_VERBOSE         );
	showopt(OPT_KEEP_OLD        );
	showopt(OPT_CREATE          );
	showopt(OPT_DEREFERENCE     );
	showopt(OPT_BZIP2           );
	showopt(OPT_INCLUDE_FROM    );
	showopt(OPT_EXCLUDE_FROM    );
	showopt(OPT_GZIP            );
	showopt(OPT_XZ              );
	showopt(OPT_COMPRESS        );
	showopt(OPT_AUTOCOMPRESS_BY_EXT);
	showopt(OPT_NOPRESERVE_TIME );
	showopt(OPT_STRIP_COMPONENTS);
	showopt(OPT_LZMA            );
	showopt(OPT_NORECURSION     );
	showopt(OPT_2COMMAND        );
	showopt(OPT_NUMERIC_OWNER   );
	showopt(OPT_NOPRESERVE_PERM );
	showopt(OPT_OVERWRITE       );
	showopt(OPT_ANY_COMPRESS    );
	bb_error_msg("base_dir:'%s'", base_dir);
	bb_error_msg("tar_filename:'%s'", tar_filename);
	bb_error_msg("verboseFlag:%d", verboseFlag);
	bb_error_msg("tar_handle->tar__to_command:'%s'", tar_handle->tar__to_command);
	bb_error_msg("tar_handle->tar__strip_components:%u", tar_handle->tar__strip_components);
	return 0;
# undef showopt
#endif
	argv += optind;

	if (verboseFlag)
		tar_handle->action_header = header_verbose_list;
	if (verboseFlag == 1)
		tar_handle->action_header = header_list;

	if (opt & OPT_EXTRACT)
		tar_handle->action_data = data_extract_all;

	if (opt & OPT_2STDOUT)
		tar_handle->action_data = data_extract_to_stdout;

	if (opt & OPT_2COMMAND) {
		putenv((char*)"TAR_FILETYPE=f");
		signal(SIGPIPE, SIG_IGN);
		tar_handle->action_data = data_extract_to_command;
		IF_FEATURE_TAR_TO_COMMAND(tar_handle->tar__to_command_shell = xstrdup(get_shell_name());)
	}

	if (opt & OPT_KEEP_OLD)
		tar_handle->ah_flags &= ~ARCHIVE_UNLINK_OLD;

	if (opt & OPT_NUMERIC_OWNER)
		tar_handle->ah_flags |= ARCHIVE_NUMERIC_OWNER;

	if (opt & OPT_NOPRESERVE_OWNER)
		tar_handle->ah_flags |= ARCHIVE_DONT_RESTORE_OWNER;

	if (opt & OPT_NOPRESERVE_PERM)
		tar_handle->ah_flags |= ARCHIVE_DONT_RESTORE_PERM;

	if (opt & OPT_OVERWRITE) {
		tar_handle->ah_flags &= ~ARCHIVE_UNLINK_OLD;
		tar_handle->ah_flags |= ARCHIVE_O_TRUNC;
	}

	if (opt & OPT_NOPRESERVE_TIME)
		tar_handle->ah_flags &= ~ARCHIVE_RESTORE_DATE;

#if ENABLE_FEATURE_TAR_FROM
	/* Convert each -X EXCLFILE to list of to-be-rejected glob patterns */
	tar_handle->reject = append_file_list_to_list(tar_handle->reject);
# if ENABLE_FEATURE_TAR_LONG_OPTIONS
	/* Append --exclude=GLOBPATTERNs to reject */
	if (excludes) {
		llist_t **p2next = &tar_handle->reject;
		while (*p2next)
			p2next = &((*p2next)->link);
		*p2next = excludes;
	}
# endif
	tar_handle->accept = append_file_list_to_list(tar_handle->accept);
#endif

	/* Setup an array of filenames to work with */
	/* TODO: This is the same as in ar, make a separate function? */
	while (*argv) {
		/* kill trailing '/' unless the string is just "/" */
		char *cp = last_char_is(*argv, '/');
		if (cp > *argv)
			*cp = '\0';
		llist_add_to_end(&tar_handle->accept, *argv);
		argv++;
	}

	if (tar_handle->accept || tar_handle->reject)
		tar_handle->filter = filter_accept_reject_list;

	/* Open the tar file */
	{
		int tar_fd = STDIN_FILENO;
		int flags = O_RDONLY;

		if (opt & OPT_CREATE) {
			/* Make sure there is at least one file to tar up */
			if (tar_handle->accept == NULL)
				bb_simple_error_msg_and_die("empty archive");

			tar_fd = STDOUT_FILENO;
			/* Mimicking GNU tar 1.15.1: */
			flags = O_WRONLY | O_CREAT | O_TRUNC;
		}

		if (LONE_DASH(tar_filename)) {
			tar_handle->src_fd = tar_fd;
			tar_handle->seek = seek_by_read;
		} else
		if (ENABLE_FEATURE_TAR_AUTODETECT
		 && ENABLE_FEATURE_SEAMLESS_LZMA
		 && flags == O_RDONLY
		 && !(opt & OPT_ANY_COMPRESS)
		 && is_suffixed_with(tar_filename, ".lzma")
		/* We do this only for .lzma files, they have no signature.
		 * All other compression formats are recognized in
		 * get_header_tar() when first tar block has invalid format.
		 * Doing it here for all filenames would falsely trigger
		 * on e.g. tarball with 1st file named "BZh5".
		 */
		) {
			tar_handle->src_fd = open_zipped(tar_filename, /*fail_if_not_compressed:*/ 0);
			if (tar_handle->src_fd < 0)
				bb_perror_msg_and_die("can't open '%s'", tar_filename);
		} else {
			tar_handle->src_fd = xopen(tar_filename, flags);
#if ENABLE_FEATURE_TAR_CREATE
			if ((OPT_GZIP | OPT_BZIP2 | OPT_XZ | OPT_LZMA) != 0 /* at least one is config-enabled */
			 && (opt & OPT_AUTOCOMPRESS_BY_EXT)
			 && flags != O_RDONLY
			) {
				if (OPT_GZIP != 0 && is_suffixed_with(tar_filename, "gz"))
					opt |= OPT_GZIP;
				if (OPT_BZIP2 != 0 && is_suffixed_with(tar_filename, "bz2"))
					opt |= OPT_BZIP2;
				if (OPT_XZ != 0 && is_suffixed_with(tar_filename, "xz"))
					opt |= OPT_XZ;
				if (OPT_LZMA != 0 && is_suffixed_with(tar_filename, "lzma"))
					opt |= OPT_LZMA;
			}
#endif
		}
	}

	if (base_dir)
		xchdir(base_dir);

#if ENABLE_FEATURE_TAR_CREATE
	/* Create an archive */
	if (opt & OPT_CREATE) {
		struct TarBallInfo *tbInfo;
# if SEAMLESS_COMPRESSION
		const char *zipMode = NULL;
		if (opt & OPT_COMPRESS)
			zipMode = "compress";
		if (opt & OPT_GZIP)
			zipMode = "gzip";
		if (opt & OPT_BZIP2)
			zipMode = "bzip2";
		if (opt & OPT_LZMA)
			zipMode = "lzma";
		if (opt & OPT_XZ)
			zipMode = "xz";
# endif
		tbInfo = xzalloc(sizeof(*tbInfo));
		tbInfo->tarFd = tar_handle->src_fd;
		tbInfo->verboseFlag = verboseFlag;
# if ENABLE_FEATURE_TAR_FROM
		tbInfo->excludeList = tar_handle->reject;
# endif
		/* NB: writeTarFile() closes tar_handle->src_fd */
		return writeTarFile(tbInfo,
				(opt & OPT_DEREFERENCE ? ACTION_FOLLOWLINKS : 0)
				| (opt & OPT_NORECURSION ? 0 : ACTION_RECURSE),
				tar_handle->accept,
				zipMode);
	}
#endif

	if (opt & OPT_ANY_COMPRESS) {
		USE_FOR_MMU(IF_DESKTOP(long long) int FAST_FUNC (*xformer)(transformer_state_t *xstate);)
		USE_FOR_NOMMU(const char *xformer_prog;)

		if (opt & OPT_COMPRESS) {
			USE_FOR_MMU(IF_FEATURE_SEAMLESS_Z(xformer = unpack_Z_stream;))
			USE_FOR_NOMMU(xformer_prog = "uncompress";)
		}
		if (opt & OPT_GZIP) {
			USE_FOR_MMU(IF_FEATURE_SEAMLESS_GZ(xformer = unpack_gz_stream;))
			USE_FOR_NOMMU(xformer_prog = "gunzip";)
		}
		if (opt & OPT_BZIP2) {
			USE_FOR_MMU(IF_FEATURE_SEAMLESS_BZ2(xformer = unpack_bz2_stream;))
			USE_FOR_NOMMU(xformer_prog = "bunzip2";)
		}
		if (opt & OPT_LZMA) {
			USE_FOR_MMU(IF_FEATURE_SEAMLESS_LZMA(xformer = unpack_lzma_stream;))
			USE_FOR_NOMMU(xformer_prog = "unlzma";)
		}
		if (opt & OPT_XZ) {
			USE_FOR_MMU(IF_FEATURE_SEAMLESS_XZ(xformer = unpack_xz_stream;))
			USE_FOR_NOMMU(xformer_prog = "unxz";)
		}

		fork_transformer_with_sig(tar_handle->src_fd, xformer, xformer_prog);
		/* Can't lseek over pipes */
		tar_handle->seek = seek_by_read;
		/*tar_handle->offset = 0; - already is */
	}

	/* Zero processed headers (== empty file) is not a valid tarball.
	 * We (ab)use bb_got_signal as exitcode here,
	 * because check_errors_in_children() uses _it_ as error indicator.
	 */
	bb_got_signal = EXIT_FAILURE;

	while (get_header_tar(tar_handle) == EXIT_SUCCESS)
		bb_got_signal = EXIT_SUCCESS; /* saw at least one header, good */

	create_links_from_list(tar_handle->link_placeholders);

	/* Check that every file that should have been extracted was */
	while (tar_handle->accept) {
		if (!find_list_entry(tar_handle->reject, tar_handle->accept->data)
		 && !find_list_entry(tar_handle->passed, tar_handle->accept->data)
		) {
			bb_error_msg_and_die("%s: not found in archive",
				tar_handle->accept->data);
		}
		tar_handle->accept = tar_handle->accept->link;
	}
	if (ENABLE_FEATURE_CLEAN_UP /* && tar_handle->src_fd != STDIN_FILENO */)
		close(tar_handle->src_fd);

	if (SEAMLESS_COMPRESSION || OPT_COMPRESS) {
		/* Set bb_got_signal to 1 if a child died with !0 exitcode */
		check_errors_in_children(0);
	}

	return bb_got_signal;
}