More -Wwrite-strings cleanup and make sure you can actually play it.

[dragonfly.git] / contrib / libarchive / archive_write_set_format_pax.c

/*-
 * Copyright (c) 2003-2004 Tim Kientzle
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer
 *    in this position and unchanged.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "archive_platform.h"
__FBSDID("$FreeBSD: src/lib/libarchive/archive_write_set_format_pax.c,v 1.26 2005/04/23 17:46:51 kientzle Exp $");

#include <sys/stat.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wchar.h>

#include "archive.h"
#include "archive_entry.h"
#include "archive_private.h"

struct pax {
        uint64_t        entry_bytes_remaining;
        uint64_t        entry_padding;
        struct archive_string   pax_header;
        char            written;
};

static void              add_pax_attr(struct archive_string *, const char *key,
                             const char *value);
static void              add_pax_attr_int(struct archive_string *,
                             const char *key, int64_t value);
static void              add_pax_attr_time(struct archive_string *,
                             const char *key, int64_t sec,
                             unsigned long nanos);
static void              add_pax_attr_w(struct archive_string *,
                             const char *key, const wchar_t *wvalue);
static int               archive_write_pax_data(struct archive *,
                             const void *, size_t);
static int               archive_write_pax_finish(struct archive *);
static int               archive_write_pax_finish_entry(struct archive *);
static int               archive_write_pax_header(struct archive *,
                             struct archive_entry *);
static char             *build_pax_attribute_name(char *dest, const char *src);
static char             *build_ustar_entry_name(char *dest, const char *src, const char *insert);
static char             *format_int(char *dest, int64_t);
static int               write_nulls(struct archive *, size_t);

/*
 * Set output format to 'restricted pax' format.
 *
 * This is the same as normal 'pax', but tries to suppress
 * the pax header whenever possible.  This is the default for
 * bsdtar, for instance.
 */
int
archive_write_set_format_pax_restricted(struct archive *a)
{
        int r;
        r = archive_write_set_format_pax(a);
        a->archive_format = ARCHIVE_FORMAT_TAR_PAX_RESTRICTED;
        a->archive_format_name = "restricted POSIX pax interchange";
        return (r);
}

/*
 * Set output format to 'pax' format.
 */
int
archive_write_set_format_pax(struct archive *a)
{
        struct pax *pax;

        if (a->format_finish != NULL)
                (a->format_finish)(a);

        pax = malloc(sizeof(*pax));
        if (pax == NULL) {
                archive_set_error(a, ENOMEM, "Can't allocate pax data");
                return (ARCHIVE_FATAL);
        }
        memset(pax, 0, sizeof(*pax));
        a->format_data = pax;

        a->pad_uncompressed = 1;
        a->format_write_header = archive_write_pax_header;
        a->format_write_data = archive_write_pax_data;
        a->format_finish = archive_write_pax_finish;
        a->format_finish_entry = archive_write_pax_finish_entry;
        a->archive_format = ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE;
        a->archive_format_name = "POSIX pax interchange";
        return (ARCHIVE_OK);
}

/*
 * Note: This code assumes that 'nanos' has the same sign as 'sec',
 * which implies that sec=-1, nanos=200000000 represents -1.2 seconds
 * and not -0.8 seconds.  This is a pretty pedantic point, as we're
 * unlikely to encounter many real files created before Jan 1, 1970,
 * much less ones with timestamps recorded to sub-second resolution.
 */
static void
add_pax_attr_time(struct archive_string *as, const char *key,
    int64_t sec, unsigned long nanos)
{
        int digit, i;
        char *t;
        /*
         * Note that each byte contributes fewer than 3 base-10
         * digits, so this will always be big enough.
         */
        char tmp[1 + 3*sizeof(sec) + 1 + 3*sizeof(nanos)];

        tmp[sizeof(tmp) - 1] = 0;
        t = tmp + sizeof(tmp) - 1;

        /* Skip trailing zeros in the fractional part. */
        for(digit = 0, i = 10; i > 0 && digit == 0; i--) {
                digit = nanos % 10;
                nanos /= 10;
        }

        /* Only format the fraction if it's non-zero. */
        if (i > 0) {
                while (i > 0) {
                        *--t = "0123456789"[digit];
                        digit = nanos % 10;
                        nanos /= 10;
                        i--;
                }
                *--t = '.';
        }
        t = format_int(t, sec);

        add_pax_attr(as, key, t);
}

static char *
format_int(char *t, int64_t i)
{
        int sign;

        if (i < 0) {
                sign = -1;
                i = -i;
        } else
                sign = 1;

        do {
                *--t = "0123456789"[i % 10];
        } while (i /= 10);
        if (sign < 0)
                *--t = '-';
        return (t);
}

static void
add_pax_attr_int(struct archive_string *as, const char *key, int64_t value)
{
        char tmp[1 + 3 * sizeof(value)];

        tmp[sizeof(tmp) - 1] = 0;
        add_pax_attr(as, key, format_int(tmp + sizeof(tmp) - 1, value));
}

static void
add_pax_attr_w(struct archive_string *as, const char *key, const wchar_t *wval)
{
        int     utf8len;
        const wchar_t *wp;
        unsigned long wc;
        char *utf8_value, *p;

        utf8len = 0;
        for (wp = wval; *wp != L'\0'; ) {
                wc = *wp++;
                if (wc <= 0x7f)
                        utf8len++;
                else if (wc <= 0x7ff)
                        utf8len += 2;
                else if (wc <= 0xffff)
                        utf8len += 3;
                else if (wc <= 0x1fffff)
                        utf8len += 4;
                else if (wc <= 0x3ffffff)
                        utf8len += 5;
                else if (wc <= 0x7fffffff)
                        utf8len += 6;
                /* Ignore larger values; UTF-8 can't encode them. */
        }

        utf8_value = malloc(utf8len + 1);
        for (wp = wval, p = utf8_value; *wp != L'\0'; ) {
                wc = *wp++;
                if (wc <= 0x7f) {
                        *p++ = (char)wc;
                } else if (wc <= 0x7ff) {
                        p[0] = 0xc0 | ((wc >> 6) & 0x1f);
                        p[1] = 0x80 | (wc & 0x3f);
                        p += 2;
                } else if (wc <= 0xffff) {
                        p[0] = 0xe0 | ((wc >> 12) & 0x0f);
                        p[1] = 0x80 | ((wc >> 6) & 0x3f);
                        p[2] = 0x80 | (wc & 0x3f);
                        p += 3;
                } else if (wc <= 0x1fffff) {
                        p[0] = 0xf0 | ((wc >> 18) & 0x07);
                        p[1] = 0x80 | ((wc >> 12) & 0x3f);
                        p[2] = 0x80 | ((wc >> 6) & 0x3f);
                        p[3] = 0x80 | (wc & 0x3f);
                        p += 4;
                } else if (wc <= 0x3ffffff) {
                        p[0] = 0xf8 | ((wc >> 24) & 0x03);
                        p[1] = 0x80 | ((wc >> 18) & 0x3f);
                        p[2] = 0x80 | ((wc >> 12) & 0x3f);
                        p[3] = 0x80 | ((wc >> 6) & 0x3f);
                        p[4] = 0x80 | (wc & 0x3f);
                        p += 5;
                } else if (wc <= 0x7fffffff) {
                        p[0] = 0xfc | ((wc >> 30) & 0x01);
                        p[1] = 0x80 | ((wc >> 24) & 0x3f);
                        p[1] = 0x80 | ((wc >> 18) & 0x3f);
                        p[2] = 0x80 | ((wc >> 12) & 0x3f);
                        p[3] = 0x80 | ((wc >> 6) & 0x3f);
                        p[4] = 0x80 | (wc & 0x3f);
                        p += 6;
                }
                /* Ignore larger values; UTF-8 can't encode them. */
        }
        *p = '\0';
        add_pax_attr(as, key, utf8_value);
        free(utf8_value);
}

/*
 * Add a key/value attribute to the pax header.  This function handles
 * the length field and various other syntactic requirements.
 */
static void
add_pax_attr(struct archive_string *as, const char *key, const char *value)
{
        int digits, i, len, next_ten;
        char tmp[1 + 3 * sizeof(int)];  /* < 3 base-10 digits per byte */

        /*-
         * PAX attributes have the following layout:
         *     <len> <space> <key> <=> <value> <nl>
         */
        len = 1 + strlen(key) + 1 + strlen(value) + 1;

        /*
         * The <len> field includes the length of the <len> field, so
         * computing the correct length is tricky.  I start by
         * counting the number of base-10 digits in 'len' and
         * computing the next higher power of 10.
         */
        next_ten = 1;
        digits = 0;
        i = len;
        while (i > 0) {
                i = i / 10;
                digits++;
                next_ten = next_ten * 10;
        }
        /*
         * For example, if string without the length field is 99
         * chars, then adding the 2 digit length "99" will force the
         * total length past 100, requiring an extra digit.  The next
         * statement adjusts for this effect.
         */
        if (len + digits >= next_ten)
                digits++;

        /* Now, we have the right length so we can build the line. */
        tmp[sizeof(tmp) - 1] = 0;       /* Null-terminate the work area. */
        archive_strcat(as, format_int(tmp + sizeof(tmp) - 1, len + digits));
        archive_strappend_char(as, ' ');
        archive_strcat(as, key);
        archive_strappend_char(as, '=');
        archive_strcat(as, value);
        archive_strappend_char(as, '\n');
}

/*
 * TODO: Consider adding 'comment' and 'charset' fields to
 * archive_entry so that clients can specify them.  Also, consider
 * adding generic key/value tags so clients can add arbitrary
 * key/value data.
 */
static int
archive_write_pax_header(struct archive *a,
    struct archive_entry *entry_original)
{
        struct archive_entry *entry_main;
        const char *linkname, *p;
        const char *hardlink;
        const wchar_t *wp, *wp2;
        const char *suffix_start;
        int need_extension, r, ret;
        struct pax *pax;
        const struct stat *st_main, *st_original;

        char paxbuff[512];
        char ustarbuff[512];
        char ustar_entry_name[256];
        char pax_entry_name[256];

        need_extension = 0;
        pax = a->format_data;
        pax->written = 1;

        st_original = archive_entry_stat(entry_original);

        hardlink = archive_entry_hardlink(entry_original);

        /* Make sure this is a type of entry that we can handle here */
        if (hardlink == NULL) {
                switch (st_original->st_mode & S_IFMT) {
                case S_IFREG:
                case S_IFLNK:
                case S_IFCHR:
                case S_IFBLK:
                case S_IFDIR:
                case S_IFIFO:
                        break;
                case S_IFSOCK:
                        archive_set_error(a, ARCHIVE_ERRNO_FILE_FORMAT,
                            "tar format cannot archive socket");
                        return (ARCHIVE_WARN);
                default:
                        archive_set_error(a, ARCHIVE_ERRNO_FILE_FORMAT,
                            "tar format cannot archive this (mode=0%lo)",
                            (unsigned long)st_original->st_mode);
                        return (ARCHIVE_WARN);
                }
        }

        /* Copy entry so we can modify it as needed. */
        entry_main = archive_entry_clone(entry_original);
        archive_string_empty(&(pax->pax_header)); /* Blank our work area. */
        st_main = archive_entry_stat(entry_main);

        /*
         * Determining whether or not the name is too big is ugly
         * because of the rules for dividing names between 'name' and
         * 'prefix' fields.  Here, I pick out the longest possible
         * suffix, then test whether the remaining prefix is too long.
         */
        wp = archive_entry_pathname_w(entry_main);
        p = archive_entry_pathname(entry_main);
        if (strlen(p) <= 100)   /* Short enough for just 'name' field */
                suffix_start = p;       /* Record a zero-length prefix */
        else
                /* Find the largest suffix that fits in 'name' field. */
                suffix_start = strchr(p + strlen(p) - 100 - 1, '/');

        /* Find non-ASCII character, if any. */
        wp2 = wp;
        while (*wp2 != L'\0' && *wp2 < 128)
                wp2++;

        /*
         * If name is too long, or has non-ASCII characters, add
         * 'path' to pax extended attrs.
         */
        if (suffix_start == NULL || suffix_start - p > 155 || *wp2 != L'\0') {
                add_pax_attr_w(&(pax->pax_header), "path", wp);
                archive_entry_set_pathname(entry_main,
                    build_ustar_entry_name(ustar_entry_name, p, NULL));
                need_extension = 1;
        }

        /* If link name is too long, add 'linkpath' to pax extended attrs. */
        linkname = hardlink;
        if (linkname == NULL)
                linkname = archive_entry_symlink(entry_main);

        if (linkname != NULL && strlen(linkname) > 100) {
                add_pax_attr(&(pax->pax_header), "linkpath", linkname);
                if (hardlink != NULL)
                        archive_entry_set_hardlink(entry_main,
                            "././@LongHardLink");
                else
                        archive_entry_set_symlink(entry_main,
                            "././@LongSymLink");
                need_extension = 1;
        }

        /* If file size is too large, add 'size' to pax extended attrs. */
        if (st_main->st_size >= (((int64_t)1) << 33)) {
                add_pax_attr_int(&(pax->pax_header), "size", st_main->st_size);
                need_extension = 1;
        }

        /* If numeric GID is too large, add 'gid' to pax extended attrs. */
        if (st_main->st_gid >= (1 << 18)) {
                add_pax_attr_int(&(pax->pax_header), "gid", st_main->st_gid);
                need_extension = 1;
        }

        /* If group name is too large, add 'gname' to pax extended attrs. */
        /* TODO: If gname has non-ASCII characters, use pax attribute. */
        p = archive_entry_gname(entry_main);
        if (p != NULL && strlen(p) > 31) {
                add_pax_attr(&(pax->pax_header), "gname", p);
                archive_entry_set_gname(entry_main, NULL);
                need_extension = 1;
        }

        /* If numeric UID is too large, add 'uid' to pax extended attrs. */
        if (st_main->st_uid >= (1 << 18)) {
                add_pax_attr_int(&(pax->pax_header), "uid", st_main->st_uid);
                need_extension = 1;
        }

        /* If user name is too large, add 'uname' to pax extended attrs. */
        /* TODO: If uname has non-ASCII characters, use pax attribute. */
        p = archive_entry_uname(entry_main);
        if (p != NULL && strlen(p) > 31) {
                add_pax_attr(&(pax->pax_header), "uname", p);
                archive_entry_set_uname(entry_main, NULL);
                need_extension = 1;
        }

        /*
         * POSIX/SUSv3 doesn't provide a standard key for large device
         * numbers.  I use the same keys here that Joerg Schilling
         * used for 'star.'  (Which, somewhat confusingly, are called
         * "devXXX" even though they code "rdev" values.)  No doubt,
         * other implementations use other keys.  Note that there's no
         * reason we can't write the same information into a number of
         * different keys.
         *
         * Of course, this is only needed for block or char device entries.
         */
        if (S_ISBLK(st_main->st_mode) ||
            S_ISCHR(st_main->st_mode)) {
                /*
                 * If rdevmajor is too large, add 'SCHILY.devmajor' to
                 * extended attributes.
                 */
                dev_t rdevmajor, rdevminor;
                rdevmajor = major(st_main->st_rdev);
                rdevminor = minor(st_main->st_rdev);
                if (rdevmajor >= (1 << 18)) {
                        add_pax_attr_int(&(pax->pax_header), "SCHILY.devmajor",
                            rdevmajor);
                        /*
                         * Non-strict formatting below means we don't
                         * have to truncate here.  Not truncating improves
                         * the chance that some more modern tar archivers
                         * (such as GNU tar 1.13) can restore the full
                         * value even if they don't understand the pax
                         * extended attributes.  See my rant below about
                         * file size fields for additional details.
                         */
                        /* archive_entry_set_rdevmajor(entry_main,
                           rdevmajor & ((1 << 18) - 1)); */
                        need_extension = 1;
                }

                /*
                 * If devminor is too large, add 'SCHILY.devminor' to
                 * extended attributes.
                 */
                if (rdevminor >= (1 << 18)) {
                        add_pax_attr_int(&(pax->pax_header), "SCHILY.devminor",
                            rdevminor);
                        /* Truncation is not necessary here, either. */
                        /* archive_entry_set_rdevminor(entry_main,
                           rdevminor & ((1 << 18) - 1)); */
                        need_extension = 1;
                }
        }

        /*
         * Technically, the mtime field in the ustar header can
         * support 33 bits, but many platforms use signed 32-bit time
         * values.  The cutoff of 0x7fffffff here is a compromise.
         * Yes, this check is duplicated just below; this helps to
         * avoid writing an mtime attribute just to handle a
         * high-resolution timestamp in "restricted pax" mode.
         */
        if (!need_extension &&
            ((st_main->st_mtime < 0) || (st_main->st_mtime >= 0x7fffffff)))
                need_extension = 1;

        /* I use a star-compatible file flag attribute. */
        p = archive_entry_fflags_text(entry_main);
        if (!need_extension && p != NULL  &&  *p != '\0')
                need_extension = 1;

        /* If there are non-trivial ACL entries, we need an extension. */
        if (!need_extension && archive_entry_acl_count(entry_original,
                ARCHIVE_ENTRY_ACL_TYPE_ACCESS) > 0)
                need_extension = 1;

        /* If there are non-trivial ACL entries, we need an extension. */
        if (!need_extension && archive_entry_acl_count(entry_original,
                ARCHIVE_ENTRY_ACL_TYPE_DEFAULT) > 0)
                need_extension = 1;

        /*
         * The following items are handled differently in "pax
         * restricted" format.  In particular, in "pax restricted"
         * format they won't be added unless need_extension is
         * already set (we're already generating an extended header, so
         * may as well include these).
         */
        if (a->archive_format != ARCHIVE_FORMAT_TAR_PAX_RESTRICTED ||
            need_extension) {

                if (st_main->st_mtime < 0  ||
                    st_main->st_mtime >= 0x7fffffff  ||
                    ARCHIVE_STAT_MTIME_NANOS(st_main) != 0)
                        add_pax_attr_time(&(pax->pax_header), "mtime",
                            st_main->st_mtime,
                            ARCHIVE_STAT_MTIME_NANOS(st_main));

                if (st_main->st_ctime != 0  ||
                    ARCHIVE_STAT_CTIME_NANOS(st_main) != 0)
                        add_pax_attr_time(&(pax->pax_header), "ctime",
                            st_main->st_ctime,
                            ARCHIVE_STAT_CTIME_NANOS(st_main));

                if (st_main->st_atime != 0  ||
                    ARCHIVE_STAT_ATIME_NANOS(st_main) != 0)
                        add_pax_attr_time(&(pax->pax_header), "atime",
                            st_main->st_atime,
                            ARCHIVE_STAT_ATIME_NANOS(st_main));

                /* I use a star-compatible file flag attribute. */
                p = archive_entry_fflags_text(entry_main);
                if (p != NULL  &&  *p != '\0')
                        add_pax_attr(&(pax->pax_header), "SCHILY.fflags", p);

                /* I use star-compatible ACL attributes. */
                wp = archive_entry_acl_text_w(entry_original,
                    ARCHIVE_ENTRY_ACL_TYPE_ACCESS |
                    ARCHIVE_ENTRY_ACL_STYLE_EXTRA_ID);
                if (wp != NULL && *wp != L'\0')
                        add_pax_attr_w(&(pax->pax_header),
                            "SCHILY.acl.access", wp);
                wp = archive_entry_acl_text_w(entry_original,
                    ARCHIVE_ENTRY_ACL_TYPE_DEFAULT |
                    ARCHIVE_ENTRY_ACL_STYLE_EXTRA_ID);
                if (wp != NULL && *wp != L'\0')
                        add_pax_attr_w(&(pax->pax_header),
                            "SCHILY.acl.default", wp);

                /* Include star-compatible metadata info. */
                /* Note: "SCHILY.dev{major,minor}" are NOT the
                 * major/minor portions of "SCHILY.dev". */
                add_pax_attr_int(&(pax->pax_header), "SCHILY.dev",
                    st_main->st_dev);
                add_pax_attr_int(&(pax->pax_header), "SCHILY.ino",
                    st_main->st_ino);
                add_pax_attr_int(&(pax->pax_header), "SCHILY.nlink",
                    st_main->st_nlink);
        }

        /* Only regular files have data. */
        if (!S_ISREG(archive_entry_mode(entry_main)))
                archive_entry_set_size(entry_main, 0);

        /*
         * Pax-restricted does not store data for hardlinks, in order
         * to improve compatibility with ustar.
         */
        if (a->archive_format != ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE &&
            hardlink != NULL)
                archive_entry_set_size(entry_main, 0);

        /*
         * XXX Full pax interchange format does permit a hardlink
         * entry to have data associated with it.  I'm not supporting
         * that here because the client expects me to tell them whether
         * or not this format expects data for hardlinks.  If I
         * don't check here, then every pax archive will end up with
         * duplicated data for hardlinks.  Someday, there may be
         * need to select this behavior, in which case the following
         * will need to be revisited. XXX
         */
        if (hardlink != NULL)
                archive_entry_set_size(entry_main, 0);

        /* Format 'ustar' header for main entry.
         *
         * The trouble with file size: If the reader can't understand
         * the file size, they may not be able to locate the next
         * entry and the rest of the archive is toast.  Pax-compliant
         * readers are supposed to ignore the file size in the main
         * header, so the question becomes how to maximize portability
         * for readers that don't support pax attribute extensions.
         * For maximum compatibility, I permit numeric extensions in
         * the main header so that the file size stored will always be
         * correct, even if it's in a format that only some
         * implementations understand.  The technique used here is:
         *
         *  a) If possible, follow the standard exactly.  This handles
         *  files up to 8 gigabytes minus 1.
         *
         *  b) If that fails, try octal but omit the field terminator.
         *  That handles files up to 64 gigabytes minus 1.
         *
         *  c) Otherwise, use base-256 extensions.  That handles files
         *  up to 2^63 in this implementation, with the potential to
         *  go up to 2^94.  That should hold us for a while. ;-)
         *
         * The non-strict formatter uses similar logic for other
         * numeric fields, though they're less critical.
         */
        __archive_write_format_header_ustar(a, ustarbuff, entry_main, -1, 0);

        /* If we built any extended attributes, write that entry first. */
        ret = ARCHIVE_OK;
        if (archive_strlen(&(pax->pax_header)) > 0) {
                struct stat st;
                struct archive_entry *pax_attr_entry;

                memset(&st, 0, sizeof(st));
                pax_attr_entry = archive_entry_new();
                p = archive_entry_pathname(entry_main);
                archive_entry_set_pathname(pax_attr_entry,
                    build_pax_attribute_name(pax_entry_name, p));
                st.st_size = archive_strlen(&(pax->pax_header));
                st.st_uid = st_main->st_uid;
                if (st.st_uid >= 1 << 18)
                        st.st_uid = (1 << 18) - 1;
                st.st_gid = st_main->st_gid;
                if (st.st_gid >= 1 << 18)
                        st.st_gid = (1 << 18) - 1;
                st.st_mode = st_main->st_mode;
                archive_entry_copy_stat(pax_attr_entry, &st);

                archive_entry_set_uname(pax_attr_entry,
                    archive_entry_uname(entry_main));
                archive_entry_set_gname(pax_attr_entry,
                    archive_entry_gname(entry_main));

                ret = __archive_write_format_header_ustar(a, paxbuff,
                    pax_attr_entry, 'x', 1);

                archive_entry_free(pax_attr_entry);

                /* Note that the 'x' header shouldn't ever fail to format */
                if (ret != 0) {
                        const char *msg = "archive_write_pax_header: "
                            "'x' header failed?!  This can't happen.\n";
                        write(2, msg, strlen(msg));
                        exit(1);
                }
                r = (a->compression_write)(a, paxbuff, 512);
                if (r != ARCHIVE_OK) {
                        pax->entry_bytes_remaining = 0;
                        pax->entry_padding = 0;
                        return (ARCHIVE_FATAL);
                }

                pax->entry_bytes_remaining = archive_strlen(&(pax->pax_header));
                pax->entry_padding = 0x1ff & (- pax->entry_bytes_remaining);

                r = (a->compression_write)(a, pax->pax_header.s,
                    archive_strlen(&(pax->pax_header)));
                if (r != ARCHIVE_OK) {
                        /* If a write fails, we're pretty much toast. */
                        return (ARCHIVE_FATAL);
                }
                /* Pad out the end of the entry. */
                r = write_nulls(a, pax->entry_padding);
                if (r != ARCHIVE_OK) {
                        /* If a write fails, we're pretty much toast. */
                        return (ARCHIVE_FATAL);
                }
                pax->entry_bytes_remaining = pax->entry_padding = 0;
        }

        /* Write the header for main entry. */
        r = (a->compression_write)(a, ustarbuff, 512);
        if (r != ARCHIVE_OK)
                return (r);

        /*
         * Inform the client of the on-disk size we're using, so
         * they can avoid unnecessarily writing a body for something
         * that we're just going to ignore.
         */
        archive_entry_set_size(entry_original, archive_entry_size(entry_main));
        pax->entry_bytes_remaining = archive_entry_size(entry_main);
        pax->entry_padding = 0x1ff & (- pax->entry_bytes_remaining);
        archive_entry_free(entry_main);

        return (ret);
}

/*
 * We need a valid name for the regular 'ustar' entry.  This routine
 * tries to hack something more-or-less reasonable.
 *
 * The approach here tries to preserve leading dir names.  We do so by
 * working with four sections:
 *   1) "prefix" directory names,
 *   2) "suffix" directory names,
 *   3) inserted dir name (optional),
 *   4) filename.
 *
 * These sections must satisfy the following requirements:
 *   * Parts 1 & 2 together form an initial portion of the dir name.
 *   * Part 3 is specified by the caller.  (It should not contain a leading
 *     or trailing '/'.)
 *   * Part 4 forms an initial portion of the base filename.
 *   * The filename must be <= 99 chars to fit the ustar 'name' field.
 *   * Parts 2, 3, 4 together must be <= 99 chars to fit the ustar 'name' fld.
 *   * Part 1 must be <= 155 chars to fit the ustar 'prefix' field.
 *   * If the original name ends in a '/', the new name must also end in a '/'
 *   * Trailing '/.' sequences may be stripped.
 *
 * Note: Recall that the ustar format does not store the '/' separating
 * parts 1 & 2, but does store the '/' separating parts 2 & 3.
 */
static char *
build_ustar_entry_name(char *dest, const char *src, const char *insert)
{
        const char *prefix, *prefix_end;
        const char *suffix, *suffix_end;
        const char *filename, *filename_end;
        char *p;
        size_t s;
        int need_slash = 0; /* Was there a trailing slash? */
        size_t suffix_length = 99;
        int insert_length;

        /* Length of additional dir element to be added. */
        if (insert == NULL)
                insert_length = 0;
        else
                /* +2 here allows for '/' before and after the insert. */
                insert_length = strlen(insert) + 2;

        /* Step 0: Quick bailout in a common case. */
        s = strlen(src);
        if (s < 100 && insert == NULL) {
                strcpy(dest, src);
                return (dest);
        }

        /* Step 1: Locate filename and enforce the length restriction. */
        filename_end = src + s;
        /* Remove trailing '/' chars and '/.' pairs. */
        for (;;) {
                if (filename_end > src && filename_end[-1] == '/') {
                        filename_end --;
                        need_slash = 1; /* Remember to restore trailing '/'. */
                        continue;
                }
                if (filename_end > src + 1 && filename_end[-1] == '.'
                    && filename_end[-2] == '/') {
                        filename_end -= 2;
                        need_slash = 1; /* "foo/." will become "foo/" */
                        continue;
                }
                break;
        }
        if (need_slash)
                suffix_length--;
        /* Find start of filename. */
        filename = filename_end - 1;
        while ((filename > src) && (*filename != '/'))
                filename --;
        if ((*filename == '/') && (filename < filename_end - 1))
                filename ++;
        /* Adjust filename_end so that filename + insert fits in 99 chars. */
        suffix_length -= insert_length;
        if (filename_end > filename + suffix_length)
                filename_end = filename + suffix_length;
        /* Calculate max size for "suffix" section (#3 above). */
        suffix_length -= filename_end - filename;

        /* Step 2: Locate the "prefix" section of the dirname, including
         * trailing '/'. */
        prefix = src;
        prefix_end = prefix + 155;
        if (prefix_end > filename)
                prefix_end = filename;
        while (prefix_end > prefix && *prefix_end != '/')
                prefix_end--;
        if ((prefix_end < filename) && (*prefix_end == '/'))
                prefix_end++;

        /* Step 3: Locate the "suffix" section of the dirname,
         * including trailing '/'. */
        suffix = prefix_end;
        suffix_end = suffix + suffix_length; /* Enforce limit. */
        if (suffix_end > filename)
                suffix_end = filename;
        if (suffix_end < suffix)
                suffix_end = suffix;
        while (suffix_end > suffix && *suffix_end != '/')
                suffix_end--;
        if ((suffix_end < filename) && (*suffix_end == '/'))
                suffix_end++;

        /* Step 4: Build the new name. */
        /* The OpenBSD strlcpy function is safer, but less portable. */
        /* Rather than maintain two versions, just use the strncpy version. */
        p = dest;
        if (prefix_end > prefix) {
                strncpy(p, prefix, prefix_end - prefix);
                p += prefix_end - prefix;
        }
        if (suffix_end > suffix) {
                strncpy(p, suffix, suffix_end - suffix);
                p += suffix_end - suffix;
        }
        if (insert != NULL) {
                if (prefix_end > prefix || suffix_end > suffix)
                        *p++ = '/';
                strcpy(p, insert);
                p += strlen(insert);
                *p++ = '/';
        }
        strncpy(p, filename, filename_end - filename);
        p += filename_end - filename;
        if (need_slash)
                *p++ = '/';
        *p++ = '\0';

        return (dest);
}

/*
 * The ustar header for the pax extended attributes must have a
 * reasonable name:  SUSv3 suggests 'dirname'/PaxHeader/'filename'
 *
 * Joerg Schiling has argued that this is unnecessary because, in practice,
 * if the pax extended attributes get extracted as regular files, noone is
 * going to bother reading those attributes to manually restore them.
 * Based on this, 'star' uses /tmp/PaxHeader/'basename' as the ustar header
 * name.  This is a tempting argument, but I'm not entirely convinced.
 * I'm also uncomfortable with the fact that "/tmp" is a Unix-ism.
 *
 * The following routine implements the SUSv3 recommendation, and is
 * much simpler because build_ustar_entry_name() above already does
 * most of the work (we just need to give it an extra path element to
 * insert and handle a few pathological cases).
 */
static char *
build_pax_attribute_name(char *dest, const char *src)
{
        char *p;

        /* Handle the null filename case. */
        if (src == NULL || *src == '\0') {
                strcpy(dest, "PaxHeader/blank");
                return (dest);
        }

        /* Prune final '/' and other unwanted final elements. */
        p = dest + strlen(dest);
        for (;;) {
                /* Ends in "/", remove the '/' */
                if (p > dest && p[-1] == '/') {
                        *--p = '\0';
                        continue;
                }
                /* Ends in "/.", remove the '.' */
                if (p > dest + 1 && p[-1] == '.'
                    && p[-2] == '/') {
                        *--p = '\0';
                        continue;
                }
                break;
        }

        /* Pathological case: After above, there was nothing left. */
        if (p == dest) {
                strcpy(dest, "/PaxHeader/rootdir");
                return (dest);
        }

        /* Convert unadorned "." into "dot" */
        if (*src == '.' && src[1] == '\0') {
                strcpy(dest, "PaxHeader/currentdir");
                return (dest);
        }

        /* General case: build a ustar-compatible name adding "/PaxHeader/". */
        build_ustar_entry_name(dest, src, "PaxHeader");

        return (dest);
}

/* Write two null blocks for the end of archive */
static int
archive_write_pax_finish(struct archive *a)
{
        struct pax *pax;
        int r;

        r = ARCHIVE_OK;
        pax = a->format_data;
        if (pax->written && a->compression_write != NULL)
                r = write_nulls(a, 512 * 2);
        archive_string_free(&pax->pax_header);
        free(pax);
        a->format_data = NULL;
        return (r);
}

static int
archive_write_pax_finish_entry(struct archive *a)
{
        struct pax *pax;
        int ret;

        pax = a->format_data;
        ret = write_nulls(a, pax->entry_bytes_remaining + pax->entry_padding);
        pax->entry_bytes_remaining = pax->entry_padding = 0;
        return (ret);
}

static int
write_nulls(struct archive *a, size_t padding)
{
        int ret, to_write;

        while (padding > 0) {
                to_write = padding < a->null_length ? padding : a->null_length;
                ret = (a->compression_write)(a, a->nulls, to_write);
                if (ret != ARCHIVE_OK)
                        return (ret);
                padding -= to_write;
        }
        return (ARCHIVE_OK);
}

static int
archive_write_pax_data(struct archive *a, const void *buff, size_t s)
{
        struct pax *pax;
        int ret;

        pax = a->format_data;
        pax->written = 1;
        if (s > pax->entry_bytes_remaining)
                s = pax->entry_bytes_remaining;

        ret = (a->compression_write)(a, buff, s);
        pax->entry_bytes_remaining -= s;
        return (ret);
}