Make sure UFS disallows mknod()'s with type VDIR.

[dragonfly.git] / contrib / libarchive-2 / libarchive / archive_write_set_format_pax.c

/*-
 * Copyright (c) 2003-2007 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.
 * 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 1.46 2008/03/15 11:04:45 kientzle Exp $");

#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif

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

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

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 ssize_t           archive_write_pax_data(struct archive_write *,
                             const void *, size_t);
static int               archive_write_pax_finish(struct archive_write *);
static int               archive_write_pax_destroy(struct archive_write *);
static int               archive_write_pax_finish_entry(struct archive_write *);
static int               archive_write_pax_header(struct archive_write *,
                             struct archive_entry *);
static char             *base64_encode(const char *src, size_t len);
static char             *build_pax_attribute_name(char *dest, const char *src);
static char             *build_ustar_entry_name(char *dest, const char *src,
                             size_t src_length, const char *insert);
static char             *format_int(char *dest, int64_t);
static int               has_non_ASCII(const wchar_t *);
static char             *url_encode(const char *in);
static int               write_nulls(struct archive_write *, 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)
{
        struct archive_write *a = (struct archive_write *)_a;
        int r;
        r = archive_write_set_format_pax(&a->archive);
        a->archive.archive_format = ARCHIVE_FORMAT_TAR_PAX_RESTRICTED;
        a->archive.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 archive_write *a = (struct archive_write *)_a;
        struct pax *pax;

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

        pax = (struct pax *)malloc(sizeof(*pax));
        if (pax == NULL) {
                archive_set_error(&a->archive, 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_destroy = archive_write_pax_destroy;
        a->format_finish_entry = archive_write_pax_finish_entry;
        a->archive.archive_format = ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE;
        a->archive.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 char *
utf8_encode(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 = (char *)malloc(utf8len + 1);
        if (utf8_value == NULL) {
                __archive_errx(1, "Not enough memory for attributes");
                return (NULL);
        }

        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';

        return (utf8_value);
}

static void
add_pax_attr_w(struct archive_string *as, const char *key, const wchar_t *wval)
{
        char *utf8_value = utf8_encode(wval);
        if (utf8_value == NULL)
                return;
        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');
}

static void
archive_write_pax_header_xattrs(struct pax *pax, struct archive_entry *entry)
{
        struct archive_string s;
        int i = archive_entry_xattr_reset(entry);

        while (i--) {
                const char *name;
                const void *value;
                char *encoded_value;
                char *url_encoded_name = NULL, *encoded_name = NULL;
                wchar_t *wcs_name = NULL;
                size_t size;

                archive_entry_xattr_next(entry, &name, &value, &size);
                /* Name is URL-encoded, then converted to wchar_t,
                 * then UTF-8 encoded. */
                url_encoded_name = url_encode(name);
                if (url_encoded_name != NULL) {
                        /* Convert narrow-character to wide-character. */
                        int wcs_length = strlen(url_encoded_name);
                        wcs_name = (wchar_t *)malloc((wcs_length + 1) * sizeof(wchar_t));
                        if (wcs_name == NULL)
                                __archive_errx(1, "No memory for xattr conversion");
                        mbstowcs(wcs_name, url_encoded_name, wcs_length);
                        wcs_name[wcs_length] = 0;
                        free(url_encoded_name); /* Done with this. */
                }
                if (wcs_name != NULL) {
                        encoded_name = utf8_encode(wcs_name);
                        free(wcs_name); /* Done with wchar_t name. */
                }

                encoded_value = base64_encode((const char *)value, size);

                if (encoded_name != NULL && encoded_value != NULL) {
                        archive_string_init(&s);
                        archive_strcpy(&s, "LIBARCHIVE.xattr.");
                        archive_strcat(&s, encoded_name);
                        add_pax_attr(&(pax->pax_header), s.s, encoded_value);
                        archive_string_free(&s);
                }
                free(encoded_name);
                free(encoded_value);
        }
}

/*
 * 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_write *a,
    struct archive_entry *entry_original)
{
        struct archive_entry *entry_main;
        const char *p;
        char *t;
        const wchar_t *wp;
        const char *suffix;
        int need_extension, r, ret;
        struct pax *pax;
        const char *hdrcharset = NULL;
        const char *hardlink;
        const char *path = NULL, *linkpath = NULL;
        const char *uname = NULL, *gname = NULL;
        const wchar_t *path_w = NULL, *linkpath_w = NULL;
        const wchar_t *uname_w = NULL, *gname_w = NULL;

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

        ret = ARCHIVE_OK;
        need_extension = 0;
        pax = (struct pax *)a->format_data;

        hardlink = archive_entry_hardlink(entry_original);

        /* Make sure this is a type of entry that we can handle here */
        if (hardlink == NULL) {
                switch (archive_entry_filetype(entry_original)) {
                case AE_IFBLK:
                case AE_IFCHR:
                case AE_IFIFO:
                case AE_IFLNK:
                case AE_IFREG:
                        break;
                case AE_IFDIR:
                        /*
                         * Ensure a trailing '/'.  Modify the original
                         * entry so the client sees the change.
                         */
                        p = archive_entry_pathname(entry_original);
                        if (p[strlen(p) - 1] != '/') {
                                t = (char *)malloc(strlen(p) + 2);
                                if (t == NULL) {
                                        archive_set_error(&a->archive, ENOMEM,
                                        "Can't allocate pax data");
                                        return(ARCHIVE_FATAL);
                                }
                                strcpy(t, p);
                                strcat(t, "/");
                                archive_entry_copy_pathname(entry_original, t);
                                free(t);
                        }
                        break;
                default:
                        archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
                            "tar format cannot archive this (type=0%lo)",
                            (unsigned long)archive_entry_filetype(entry_original));
                        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. */

        /*
         * First, check the name fields and see if any of them
         * require binary coding.  If any of them does, then all of
         * them do.
         */
        hdrcharset = NULL;
        path = archive_entry_pathname(entry_main);
        path_w = archive_entry_pathname_w(entry_main);
        if (path != NULL && path_w == NULL) {
                archive_set_error(&a->archive, EILSEQ,
                    "Can't translate pathname '%s' to UTF-8", path);
                ret = ARCHIVE_WARN;
                hdrcharset = "BINARY";
        }
        uname = archive_entry_uname(entry_main);
        uname_w = archive_entry_uname_w(entry_main);
        if (uname != NULL && uname_w == NULL) {
                archive_set_error(&a->archive, EILSEQ,
                    "Can't translate uname '%s' to UTF-8", uname);
                ret = ARCHIVE_WARN;
                hdrcharset = "BINARY";
        }
        gname = archive_entry_gname(entry_main);
        gname_w = archive_entry_gname_w(entry_main);
        if (gname != NULL && gname_w == NULL) {
                archive_set_error(&a->archive, EILSEQ,
                    "Can't translate gname '%s' to UTF-8", gname);
                ret = ARCHIVE_WARN;
                hdrcharset = "BINARY";
        }
        linkpath = hardlink;
        if (linkpath != NULL) {
                linkpath_w = archive_entry_hardlink_w(entry_main);
        } else {
                linkpath = archive_entry_symlink(entry_main);
                if (linkpath != NULL)
                        linkpath_w = archive_entry_symlink_w(entry_main);
        }
        if (linkpath != NULL && linkpath_w == NULL) {
                archive_set_error(&a->archive, EILSEQ,
                    "Can't translate linkpath '%s' to UTF-8", linkpath);
                ret = ARCHIVE_WARN;
                hdrcharset = "BINARY";
        }

        /* Store the header encoding first, to be nice to readers. */
        if (hdrcharset != NULL)
                add_pax_attr(&(pax->pax_header), "hdrcharset", hdrcharset);


        /*
         * If name is too long, or has non-ASCII characters, add
         * 'path' to pax extended attrs.  (Note that an unconvertible
         * name must have non-ASCII characters.)
         */
        if (path == NULL) {
                /* We don't have a narrow version, so we have to store
                 * the wide version. */
                add_pax_attr_w(&(pax->pax_header), "path", path_w);
                archive_entry_set_pathname(entry_main, "@WidePath");
                need_extension = 1;
        } else if (has_non_ASCII(path_w)) {
                /* We have non-ASCII characters. */
                if (path_w == NULL || hdrcharset != NULL) {
                        /* Can't do UTF-8, so store it raw. */
                        add_pax_attr(&(pax->pax_header), "path", path);
                } else {
                        /* Store UTF-8 */
                        add_pax_attr_w(&(pax->pax_header),
                            "path", path_w);
                }
                archive_entry_set_pathname(entry_main,
                    build_ustar_entry_name(ustar_entry_name,
                        path, strlen(path), NULL));
                need_extension = 1;
        } else {
                /* We have an all-ASCII path; we'd like to just store
                 * it in the ustar header if it will fit.  Yes, this
                 * duplicates some of the logic in
                 * write_set_format_ustar.c
                 */
                if (strlen(path) <= 100) {
                        /* Fits in the old 100-char tar name field. */
                } else {
                        /* Find largest suffix that will fit. */
                        /* Note: strlen() > 100, so strlen() - 100 - 1 >= 0 */
                        suffix = strchr(path + strlen(path) - 100 - 1, '/');
                        /* Don't attempt an empty prefix. */
                        if (suffix == path)
                                suffix = strchr(suffix + 1, '/');
                        /* We can put it in the ustar header if it's
                         * all ASCII and it's either <= 100 characters
                         * or can be split at a '/' into a prefix <=
                         * 155 chars and a suffix <= 100 chars.  (Note
                         * the strchr() above will return NULL exactly
                         * when the path can't be split.)
                         */
                        if (suffix == NULL       /* Suffix > 100 chars. */
                            || suffix[1] == '\0'    /* empty suffix */
                            || suffix - path > 155)  /* Prefix > 155 chars */
                        {
                                if (path_w == NULL || hdrcharset != NULL) {
                                        /* Can't do UTF-8, so store it raw. */
                                        add_pax_attr(&(pax->pax_header),
                                            "path", path);
                                } else {
                                        /* Store UTF-8 */
                                        add_pax_attr_w(&(pax->pax_header),
                                            "path", path_w);
                                }
                                archive_entry_set_pathname(entry_main,
                                    build_ustar_entry_name(ustar_entry_name,
                                        path, strlen(path), NULL));
                                need_extension = 1;
                        }
                }
        }

        if (linkpath != NULL) {
                /* If link name is too long or has non-ASCII characters, add
                 * 'linkpath' to pax extended attrs. */
                if (strlen(linkpath) > 100 || linkpath_w == NULL
                    || linkpath_w == NULL || has_non_ASCII(linkpath_w)) {
                        if (linkpath_w == NULL || hdrcharset != NULL)
                                /* If the linkpath is not convertible
                                 * to wide, or we're encoding in
                                 * binary anyway, store it raw. */
                                add_pax_attr(&(pax->pax_header),
                                    "linkpath", linkpath);
                        else
                                /* If the link is long or has a
                                 * non-ASCII character, store it as a
                                 * pax extended attribute. */
                                add_pax_attr_w(&(pax->pax_header),
                                    "linkpath", linkpath_w);
                        if (strlen(linkpath) > 100) {
                                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 (archive_entry_size(entry_main) >= (((int64_t)1) << 33)) {
                add_pax_attr_int(&(pax->pax_header), "size",
                    archive_entry_size(entry_main));
                need_extension = 1;
        }

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

        /* If group name is too large or has non-ASCII characters, add
         * 'gname' to pax extended attrs. */
        if (gname != NULL) {
                if (strlen(gname) > 31
                    || gname_w == NULL
                    || has_non_ASCII(gname_w))
                {
                        if (gname_w == NULL || hdrcharset != NULL) {
                                add_pax_attr(&(pax->pax_header),
                                    "gname", gname);
                        } else  {
                                add_pax_attr_w(&(pax->pax_header),
                                    "gname", gname_w);
                        }
                        need_extension = 1;
                }
        }

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

        /* Add 'uname' to pax extended attrs if necessary. */
        if (uname != NULL) {
                if (strlen(uname) > 31
                    || uname_w == NULL
                    || has_non_ASCII(uname_w))
                {
                        if (uname_w == NULL || hdrcharset != NULL) {
                                add_pax_attr(&(pax->pax_header),
                                    "uname", uname);
                        } else {
                                add_pax_attr_w(&(pax->pax_header),
                                    "uname", uname_w);
                        }
                        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 (archive_entry_filetype(entry_main) == AE_IFBLK
            || archive_entry_filetype(entry_main) == AE_IFCHR) {
                /*
                 * If rdevmajor is too large, add 'SCHILY.devmajor' to
                 * extended attributes.
                 */
                dev_t rdevmajor, rdevminor;
                rdevmajor = archive_entry_rdevmajor(entry_main);
                rdevminor = archive_entry_rdevminor(entry_main);
                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 &&
            ((archive_entry_mtime(entry_main) < 0)
                || (archive_entry_mtime(entry_main) >= 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;

        /* If there are extended attributes, we need an extension */
        if (!need_extension && archive_entry_xattr_count(entry_original) > 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.archive_format != ARCHIVE_FORMAT_TAR_PAX_RESTRICTED ||
            need_extension) {

                if (archive_entry_mtime(entry_main) < 0  ||
                    archive_entry_mtime(entry_main) >= 0x7fffffff  ||
                    archive_entry_mtime_nsec(entry_main) != 0)
                        add_pax_attr_time(&(pax->pax_header), "mtime",
                            archive_entry_mtime(entry_main),
                            archive_entry_mtime_nsec(entry_main));

                if (archive_entry_ctime(entry_main) != 0  ||
                    archive_entry_ctime_nsec(entry_main) != 0)
                        add_pax_attr_time(&(pax->pax_header), "ctime",
                            archive_entry_ctime(entry_main),
                            archive_entry_ctime_nsec(entry_main));

                if (archive_entry_atime(entry_main) != 0 ||
                    archive_entry_atime_nsec(entry_main) != 0)
                        add_pax_attr_time(&(pax->pax_header), "atime",
                            archive_entry_atime(entry_main),
                            archive_entry_atime_nsec(entry_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",
                    archive_entry_dev(entry_main));
                add_pax_attr_int(&(pax->pax_header), "SCHILY.ino",
                    archive_entry_ino(entry_main));
                add_pax_attr_int(&(pax->pax_header), "SCHILY.nlink",
                    archive_entry_nlink(entry_main));

                /* Store extended attributes */
                archive_write_pax_header_xattrs(pax, entry_original);
        }

        /* Only regular files have data. */
        if (archive_entry_filetype(entry_main) != AE_IFREG)
                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.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. */
        if (archive_strlen(&(pax->pax_header)) > 0) {
                struct archive_entry *pax_attr_entry;
                time_t s;
                uid_t uid;
                gid_t gid;
                mode_t mode;
                long ns;

                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));
                archive_entry_set_size(pax_attr_entry,
                    archive_strlen(&(pax->pax_header)));
                /* Copy uid/gid (but clip to ustar limits). */
                uid = archive_entry_uid(entry_main);
                if (uid >= 1 << 18)
                        uid = (1 << 18) - 1;
                archive_entry_set_uid(pax_attr_entry, uid);
                gid = archive_entry_gid(entry_main);
                if (gid >= 1 << 18)
                        gid = (1 << 18) - 1;
                archive_entry_set_gid(pax_attr_entry, gid);
                /* Copy mode over (but not setuid/setgid bits) */
                mode = archive_entry_mode(entry_main);
#ifdef S_ISUID
                mode &= ~S_ISUID;
#endif
#ifdef S_ISGID
                mode &= ~S_ISGID;
#endif
#ifdef S_ISVTX
                mode &= ~S_ISVTX;
#endif
                archive_entry_set_mode(pax_attr_entry, mode);

                /* Copy uname/gname. */
                archive_entry_set_uname(pax_attr_entry,
                    archive_entry_uname(entry_main));
                archive_entry_set_gname(pax_attr_entry,
                    archive_entry_gname(entry_main));

                /* Copy mtime, but clip to ustar limits. */
                s = archive_entry_mtime(entry_main);
                ns = archive_entry_mtime_nsec(entry_main);
                if (s < 0) { s = 0; ns = 0; }
                if (s > 0x7fffffff) { s = 0x7fffffff; ns = 0; }
                archive_entry_set_mtime(pax_attr_entry, s, ns);

                /* Ditto for atime. */
                s = archive_entry_atime(entry_main);
                ns = archive_entry_atime_nsec(entry_main);
                if (s < 0) { s = 0; ns = 0; }
                if (s > 0x7fffffff) { s = 0x7fffffff; ns = 0; }
                archive_entry_set_atime(pax_attr_entry, s, ns);

                /* Standard ustar doesn't support ctime. */
                archive_entry_set_ctime(pax_attr_entry, 0, 0);

                r = __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 (r != 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->compressor.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 & (-(int64_t)pax->entry_bytes_remaining);

                r = (a->compressor.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->compressor.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 & (-(int64_t)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, size_t src_length,
    const char *insert)
{
        const char *prefix, *prefix_end;
        const char *suffix, *suffix_end;
        const char *filename, *filename_end;
        char *p;
        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. */
        if (src_length < 100 && insert == NULL) {
                strncpy(dest, src, src_length);
                dest[src_length] = '\0';
                return (dest);
        }

        /* Step 1: Locate filename and enforce the length restriction. */
        filename_end = src + src_length;
        /* 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) {
                /* Note: assume insert does not have leading or trailing '/' */
                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 requires 'dirname'/PaxHeader.'pid'/'filename'
 * where 'pid' is the PID of the archiving process.  Unfortunately,
 * that makes testing a pain since the output varies for each run,
 * so I'm sticking with the simpler 'dirname'/PaxHeader/'filename'
 * for now.  (Someday, I'll make this settable.  Then I can use the
 * SUS recommendation as default and test harnesses can override it
 * to get predictable results.)
 *
 * Joerg Schilling 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, in part because it's simpler than the SUSv3
 * recommendation, but I'm not entirely convinced.  I'm also
 * uncomfortable with the fact that "/tmp" is a Unix-ism.
 *
 * The following routine leverages build_ustar_entry_name() above and
 * so is simpler than you might think.  It just needs to provide the
 * additional path element and handle a few pathological cases).
 */
static char *
build_pax_attribute_name(char *dest, const char *src)
{
        char buff[64];
        const 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 = src + strlen(src);
        for (;;) {
                /* Ends in "/", remove the '/' */
                if (p > src && p[-1] == '/') {
                        --p;
                        continue;
                }
                /* Ends in "/.", remove the '.' */
                if (p > src + 1 && p[-1] == '.'
                    && p[-2] == '/') {
                        --p;
                        continue;
                }
                break;
        }

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

        /* Convert unadorned "." into a suitable filename. */
        if (*src == '.' && p == src + 1) {
                strcpy(dest, "PaxHeader/currentdir");
                return (dest);
        }

        /*
         * TODO: Push this string into the 'pax' structure to avoid
         * recomputing it every time.  That will also open the door
         * to having clients override it.
         */
#if HAVE_GETPID && 0  /* Disable this for now; see above comment. */
        sprintf(buff, "PaxHeader.%d", getpid());
#else
        /* If the platform can't fetch the pid, don't include it. */
        strcpy(buff, "PaxHeader");
#endif
        /* General case: build a ustar-compatible name adding "/PaxHeader/". */
        build_ustar_entry_name(dest, src, p - src, buff);

        return (dest);
}

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

        if (a->compressor.write == NULL)
                return (ARCHIVE_OK);

        pax = (struct pax *)a->format_data;
        r = write_nulls(a, 512 * 2);
        return (r);
}

static int
archive_write_pax_destroy(struct archive_write *a)
{
        struct pax *pax;

        pax = (struct pax *)a->format_data;
        archive_string_free(&pax->pax_header);
        free(pax);
        a->format_data = NULL;
        return (ARCHIVE_OK);
}

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

        pax = (struct 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_write *a, size_t padding)
{
        int ret, to_write;

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

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

        pax = (struct pax *)a->format_data;
        if (s > pax->entry_bytes_remaining)
                s = pax->entry_bytes_remaining;

        ret = (a->compressor.write)(a, buff, s);
        pax->entry_bytes_remaining -= s;
        if (ret == ARCHIVE_OK)
                return (s);
        else
                return (ret);
}

static int
has_non_ASCII(const wchar_t *wp)
{
        if (wp == NULL)
                return (1);
        while (*wp != L'\0' && *wp < 128)
                wp++;
        return (*wp != L'\0');
}

/*
 * Used by extended attribute support; encodes the name
 * so that there will be no '=' characters in the result.
 */
static char *
url_encode(const char *in)
{
        const char *s;
        char *d;
        int out_len = 0;
        char *out;

        for (s = in; *s != '\0'; s++) {
                if (*s < 33 || *s > 126 || *s == '%' || *s == '=')
                        out_len += 3;
                else
                        out_len++;
        }

        out = (char *)malloc(out_len + 1);
        if (out == NULL)
                return (NULL);

        for (s = in, d = out; *s != '\0'; s++) {
                /* encode any non-printable ASCII character or '%' or '=' */
                if (*s < 33 || *s > 126 || *s == '%' || *s == '=') {
                        /* URL encoding is '%' followed by two hex digits */
                        *d++ = '%';
                        *d++ = "0123456789ABCDEF"[0x0f & (*s >> 4)];
                        *d++ = "0123456789ABCDEF"[0x0f & *s];
                } else {
                        *d++ = *s;
                }
        }
        *d = '\0';
        return (out);
}

/*
 * Encode a sequence of bytes into a C string using base-64 encoding.
 *
 * Returns a null-terminated C string allocated with malloc(); caller
 * is responsible for freeing the result.
 */
static char *
base64_encode(const char *s, size_t len)
{
        static const char digits[64] =
            { 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O',
              'P','Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d',
              'e','f','g','h','i','j','k','l','m','n','o','p','q','r','s',
              't','u','v','w','x','y','z','0','1','2','3','4','5','6','7',
              '8','9','+','/' };
        int v;
        char *d, *out;

        /* 3 bytes becomes 4 chars, but round up and allow for trailing NUL */
        out = (char *)malloc((len * 4 + 2) / 3 + 1);
        if (out == NULL)
                return (NULL);
        d = out;

        /* Convert each group of 3 bytes into 4 characters. */
        while (len >= 3) {
                v = (((int)s[0] << 16) & 0xff0000)
                    | (((int)s[1] << 8) & 0xff00)
                    | (((int)s[2]) & 0x00ff);
                s += 3;
                len -= 3;
                *d++ = digits[(v >> 18) & 0x3f];
                *d++ = digits[(v >> 12) & 0x3f];
                *d++ = digits[(v >> 6) & 0x3f];
                *d++ = digits[(v) & 0x3f];
        }
        /* Handle final group of 1 byte (2 chars) or 2 bytes (3 chars). */
        switch (len) {
        case 0: break;
        case 1:
                v = (((int)s[0] << 16) & 0xff0000);
                *d++ = digits[(v >> 18) & 0x3f];
                *d++ = digits[(v >> 12) & 0x3f];
                break;
        case 2:
                v = (((int)s[0] << 16) & 0xff0000)
                    | (((int)s[1] << 8) & 0xff00);
                *d++ = digits[(v >> 18) & 0x3f];
                *d++ = digits[(v >> 12) & 0x3f];
                *d++ = digits[(v >> 6) & 0x3f];
                break;
        }
        /* Add trailing NUL character so output is a valid C string. */
        *d++ = '\0';
        return (out);
}