/* 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;
}