Import libarchive 2.0.28.

[dragonfly/vkernel-mp.git] / contrib / libarchive-2.0 / libarchive / archive_read_support_format_tar.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_read_support_format_tar.c,v 1.52 2007/04/03 23:53:55 cperciva Exp $");

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef MAJOR_IN_MKDEV
#include <sys/mkdev.h>
#else
#ifdef MAJOR_IN_SYSMACROS
#include <sys/sysmacros.h>
#endif
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include <stddef.h>
/* #include <stdint.h> */ /* See archive_platform.h */
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

/* Obtain suitable wide-character manipulation functions. */
#ifdef HAVE_WCHAR_H
#include <wchar.h>
#else
/* Good enough for equality testing, which is all we need. */
static int wcscmp(const wchar_t *s1, const wchar_t *s2)
{
        int diff = *s1 - *s2;
        while (*s1 && diff == 0)
                diff = (int)*++s1 - (int)*++s2;
        return diff;
}
/* Good enough for equality testing, which is all we need. */
static int wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t n)
{
        int diff = *s1 - *s2;
        while (*s1 && diff == 0 && n-- > 0)
                diff = (int)*++s1 - (int)*++s2;
        return diff;
}
static size_t wcslen(const wchar_t *s)
{
        const wchar_t *p = s;
        while (*p)
                p++;
        return p - s;
}
#endif

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

/*
 * Layout of POSIX 'ustar' tar header.
 */
struct archive_entry_header_ustar {
        char    name[100];
        char    mode[8];
        char    uid[8];
        char    gid[8];
        char    size[12];
        char    mtime[12];
        char    checksum[8];
        char    typeflag[1];
        char    linkname[100];  /* "old format" header ends here */
        char    magic[6];       /* For POSIX: "ustar\0" */
        char    version[2];     /* For POSIX: "00" */
        char    uname[32];
        char    gname[32];
        char    rdevmajor[8];
        char    rdevminor[8];
        char    prefix[155];
};

/*
 * Structure of GNU tar header
 */
struct gnu_sparse {
        char    offset[12];
        char    numbytes[12];
};

struct archive_entry_header_gnutar {
        char    name[100];
        char    mode[8];
        char    uid[8];
        char    gid[8];
        char    size[12];
        char    mtime[12];
        char    checksum[8];
        char    typeflag[1];
        char    linkname[100];
        char    magic[8];  /* "ustar  \0" (note blank/blank/null at end) */
        char    uname[32];
        char    gname[32];
        char    rdevmajor[8];
        char    rdevminor[8];
        char    atime[12];
        char    ctime[12];
        char    offset[12];
        char    longnames[4];
        char    unused[1];
        struct gnu_sparse sparse[4];
        char    isextended[1];
        char    realsize[12];
        /*
         * GNU doesn't use POSIX 'prefix' field; they use the 'L' (longname)
         * entry instead.
         */
};

/*
 * Data specific to this format.
 */
struct sparse_block {
        struct sparse_block     *next;
        off_t   offset;
        off_t   remaining;
};

struct tar {
        struct archive_string    acl_text;
        struct archive_string    entry_name;
        struct archive_string    entry_linkname;
        struct archive_string    entry_uname;
        struct archive_string    entry_gname;
        struct archive_string    longlink;
        struct archive_string    longname;
        struct archive_string    pax_header;
        struct archive_string    pax_global;
        wchar_t                 *pax_entry;
        size_t                   pax_entry_length;
        int                      header_recursion_depth;
        off_t                    entry_bytes_remaining;
        off_t                    entry_offset;
        off_t                    entry_padding;
        struct sparse_block     *sparse_list;
};

static size_t   UTF8_mbrtowc(wchar_t *pwc, const char *s, size_t n);
static int      archive_block_is_null(const unsigned char *p);
static char     *base64_decode(const wchar_t *, size_t, size_t *);
static int      gnu_read_sparse_data(struct archive_read *, struct tar *,
                    const struct archive_entry_header_gnutar *header);
static void     gnu_parse_sparse_data(struct archive_read *, struct tar *,
                    const struct gnu_sparse *sparse, int length);
static int      header_Solaris_ACL(struct archive_read *,  struct tar *,
                    struct archive_entry *, struct stat *, const void *);
static int      header_common(struct archive_read *,  struct tar *,
                    struct archive_entry *, struct stat *, const void *);
static int      header_old_tar(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *);
static int      header_pax_extensions(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *);
static int      header_pax_global(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *h);
static int      header_longlink(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *h);
static int      header_longname(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *h);
static int      header_volume(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *h);
static int      header_ustar(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *h);
static int      header_gnutar(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, const void *h);
static int      archive_read_format_tar_bid(struct archive_read *);
static int      archive_read_format_tar_cleanup(struct archive_read *);
static int      archive_read_format_tar_read_data(struct archive_read *a,
                    const void **buff, size_t *size, off_t *offset);
static int      archive_read_format_tar_skip(struct archive_read *a);
static int      archive_read_format_tar_read_header(struct archive_read *,
                    struct archive_entry *);
static int      checksum(struct archive_read *, const void *);
static int      pax_attribute(struct archive_entry *, struct stat *,
                    wchar_t *key, wchar_t *value);
static int      pax_header(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *, char *attr);
static void     pax_time(const wchar_t *, int64_t *sec, long *nanos);
static int      read_body_to_string(struct archive_read *, struct tar *,
                    struct archive_string *, const void *h);
static int64_t  tar_atol(const char *, unsigned);
static int64_t  tar_atol10(const wchar_t *, unsigned);
static int64_t  tar_atol256(const char *, unsigned);
static int64_t  tar_atol8(const char *, unsigned);
static int      tar_read_header(struct archive_read *, struct tar *,
                    struct archive_entry *, struct stat *);
static int      tohex(int c);
static char     *url_decode(const char *);
static int      utf8_decode(wchar_t *, const char *, size_t length);
static char     *wide_to_narrow(const wchar_t *wval);

/*
 * ANSI C99 defines constants for these, but not everyone supports
 * those constants, so I define a couple of static variables here and
 * compute the values.  These calculations should be portable to any
 * 2s-complement architecture.
 */
#ifdef UINT64_MAX
static const uint64_t max_uint64 = UINT64_MAX;
#else
static const uint64_t max_uint64 = ~(uint64_t)0;
#endif
#ifdef INT64_MAX
static const int64_t max_int64 = INT64_MAX;
#else
static const int64_t max_int64 = (int64_t)((~(uint64_t)0) >> 1);
#endif
#ifdef INT64_MIN
static const int64_t min_int64 = INT64_MIN;
#else
static const int64_t min_int64 = (int64_t)(~((~(uint64_t)0) >> 1));
#endif

int
archive_read_support_format_gnutar(struct archive *a)
{
        return (archive_read_support_format_tar(a));
}


int
archive_read_support_format_tar(struct archive *_a)
{
        struct archive_read *a = (struct archive_read *)_a;
        struct tar *tar;
        int r;

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

        r = __archive_read_register_format(a, tar,
            archive_read_format_tar_bid,
            archive_read_format_tar_read_header,
            archive_read_format_tar_read_data,
            archive_read_format_tar_skip,
            archive_read_format_tar_cleanup);

        if (r != ARCHIVE_OK)
                free(tar);
        return (ARCHIVE_OK);
}

static int
archive_read_format_tar_cleanup(struct archive_read *a)
{
        struct tar *tar;

        tar = (struct tar *)*(a->pformat_data);
        archive_string_free(&tar->acl_text);
        archive_string_free(&tar->entry_name);
        archive_string_free(&tar->entry_linkname);
        archive_string_free(&tar->entry_uname);
        archive_string_free(&tar->entry_gname);
        archive_string_free(&tar->pax_global);
        archive_string_free(&tar->pax_header);
        if (tar->pax_entry != NULL)
                free(tar->pax_entry);
        free(tar);
        *(a->pformat_data) = NULL;
        return (ARCHIVE_OK);
}


static int
archive_read_format_tar_bid(struct archive_read *a)
{
        int bid;
        ssize_t bytes_read;
        const void *h;
        const struct archive_entry_header_ustar *header;

        /*
         * If we're already reading a non-tar file, don't
         * bother to bid.
         */
        if (a->archive.archive_format != 0 &&
            (a->archive.archive_format & ARCHIVE_FORMAT_BASE_MASK) !=
            ARCHIVE_FORMAT_TAR)
                return (0);
        bid = 0;

        /*
         * If we're already reading a tar format, start the bid at 1 as
         * a failsafe.
         */
        if ((a->archive.archive_format & ARCHIVE_FORMAT_BASE_MASK) ==
            ARCHIVE_FORMAT_TAR)
                bid++;

        /* Now let's look at the actual header and see if it matches. */
        if (a->compression_read_ahead != NULL)
                bytes_read = (a->compression_read_ahead)(a, &h, 512);
        else
                bytes_read = 0; /* Empty file. */
        if (bytes_read < 0)
                return (ARCHIVE_FATAL);
        if (bytes_read == 0  &&  bid > 0) {
                /* An archive without a proper end-of-archive marker. */
                /* Hold our nose and bid 1 anyway. */
                return (1);
        }
        if (bytes_read < 512) {
                /* If it's a new archive, then just return a zero bid. */
                if (bid == 0)
                        return (0);
                /*
                 * If we already know this is a tar archive,
                 * then we have a problem.
                 */
                archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
                    "Truncated tar archive");
                return (ARCHIVE_FATAL);
        }

        /* If it's an end-of-archive mark, we can handle it. */
        if ((*(const char *)h) == 0 && archive_block_is_null((const unsigned char *)h)) {
                /* If it's a known tar file, end-of-archive is definite. */
                if ((a->archive.archive_format & ARCHIVE_FORMAT_BASE_MASK) ==
                    ARCHIVE_FORMAT_TAR)
                        return (512);
                /* Empty archive? */
                return (1);
        }

        /* If it's not an end-of-archive mark, it must have a valid checksum.*/
        if (!checksum(a, h))
                return (0);
        bid += 48;  /* Checksum is usually 6 octal digits. */

        header = (const struct archive_entry_header_ustar *)h;

        /* Recognize POSIX formats. */
        if ((memcmp(header->magic, "ustar\0", 6) == 0)
            &&(memcmp(header->version, "00", 2)==0))
                bid += 56;

        /* Recognize GNU tar format. */
        if ((memcmp(header->magic, "ustar ", 6) == 0)
            &&(memcmp(header->version, " \0", 2)==0))
                bid += 56;

        /* Type flag must be null, digit or A-Z, a-z. */
        if (header->typeflag[0] != 0 &&
            !( header->typeflag[0] >= '0' && header->typeflag[0] <= '9') &&
            !( header->typeflag[0] >= 'A' && header->typeflag[0] <= 'Z') &&
            !( header->typeflag[0] >= 'a' && header->typeflag[0] <= 'z') )
                return (0);
        bid += 2;  /* 6 bits of variation in an 8-bit field leaves 2 bits. */

        /* Sanity check: Look at first byte of mode field. */
        switch (255 & (unsigned)header->mode[0]) {
        case 0: case 255:
                /* Base-256 value: No further verification possible! */
                break;
        case ' ': /* Not recommended, but not illegal, either. */
                break;
        case '0': case '1': case '2': case '3':
        case '4': case '5': case '6': case '7':
                /* Octal Value. */
                /* TODO: Check format of remainder of this field. */
                break;
        default:
                /* Not a valid mode; bail out here. */
                return (0);
        }
        /* TODO: Sanity test uid/gid/size/mtime/rdevmajor/rdevminor fields. */

        return (bid);
}

/*
 * The function invoked by archive_read_header().  This
 * just sets up a few things and then calls the internal
 * tar_read_header() function below.
 */
static int
archive_read_format_tar_read_header(struct archive_read *a,
    struct archive_entry *entry)
{
        /*
         * When converting tar archives to cpio archives, it is
         * essential that each distinct file have a distinct inode
         * number.  To simplify this, we keep a static count here to
         * assign fake dev/inode numbers to each tar entry.  Note that
         * pax format archives may overwrite this with something more
         * useful.
         *
         * Ideally, we would track every file read from the archive so
         * that we could assign the same dev/ino pair to hardlinks,
         * but the memory required to store a complete lookup table is
         * probably not worthwhile just to support the relatively
         * obscure tar->cpio conversion case.
         */
        static int default_inode;
        static int default_dev;
        struct stat st;
        struct tar *tar;
        const char *p;
        int r;
        size_t l;

        memset(&st, 0, sizeof(st));
        /* Assign default device/inode values. */
        st.st_dev = 1 + default_dev; /* Don't use zero. */
        st.st_ino = ++default_inode; /* Don't use zero. */
        /* Limit generated st_ino number to 16 bits. */
        if (default_inode >= 0xffff) {
                ++default_dev;
                default_inode = 0;
        }

        tar = (struct tar *)*(a->pformat_data);
        tar->entry_offset = 0;

        r = tar_read_header(a, tar, entry, &st);

        if (r == ARCHIVE_OK) {
                /*
                 * "Regular" entry with trailing '/' is really
                 * directory: This is needed for certain old tar
                 * variants and even for some broken newer ones.
                 */
                p = archive_entry_pathname(entry);
                l = strlen(p);
                if (S_ISREG(st.st_mode) && p[l-1] == '/') {
                        st.st_mode &= ~S_IFMT;
                        st.st_mode |= S_IFDIR;
                }

                /* Copy the final stat data into the entry. */
                archive_entry_copy_stat(entry, &st);
        }
        return (r);
}

static int
archive_read_format_tar_read_data(struct archive_read *a,
    const void **buff, size_t *size, off_t *offset)
{
        ssize_t bytes_read;
        struct tar *tar;
        struct sparse_block *p;

        tar = (struct tar *)*(a->pformat_data);
        if (tar->sparse_list != NULL) {
                /* Remove exhausted entries from sparse list. */
                while (tar->sparse_list != NULL &&
                    tar->sparse_list->remaining == 0) {
                        p = tar->sparse_list;
                        tar->sparse_list = p->next;
                        free(p);
                }
                if (tar->sparse_list == NULL) {
                        /* We exhausted the entire sparse list. */
                        tar->entry_bytes_remaining = 0;
                }
        }

        if (tar->entry_bytes_remaining > 0) {
                bytes_read = (a->compression_read_ahead)(a, buff, 1);
                if (bytes_read == 0) {
                        archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                            "Truncated tar archive");
                        return (ARCHIVE_FATAL);
                }
                if (bytes_read < 0)
                        return (ARCHIVE_FATAL);
                if (bytes_read > tar->entry_bytes_remaining)
                        bytes_read = tar->entry_bytes_remaining;
                if (tar->sparse_list != NULL) {
                        /* Don't read more than is available in the
                         * current sparse block. */
                        if (tar->sparse_list->remaining < bytes_read)
                                bytes_read = tar->sparse_list->remaining;
                        tar->entry_offset = tar->sparse_list->offset;
                        tar->sparse_list->remaining -= bytes_read;
                        tar->sparse_list->offset += bytes_read;
                }
                *size = bytes_read;
                *offset = tar->entry_offset;
                tar->entry_offset += bytes_read;
                tar->entry_bytes_remaining -= bytes_read;
                (a->compression_read_consume)(a, bytes_read);
                return (ARCHIVE_OK);
        } else {
                if ((a->compression_skip)(a, tar->entry_padding) < 0)
                        return (ARCHIVE_FATAL);
                tar->entry_padding = 0;
                *buff = NULL;
                *size = 0;
                *offset = tar->entry_offset;
                return (ARCHIVE_EOF);
        }
}

static int
archive_read_format_tar_skip(struct archive_read *a)
{
        off_t bytes_skipped;
        struct tar* tar;
        struct sparse_block *p;

        tar = (struct tar *)*(a->pformat_data);

        /*
         * Compression layer skip functions are required to either skip the
         * length requested or fail, so we can rely upon the entire entry
         * plus padding being skipped.
         */
        bytes_skipped = (a->compression_skip)(a, tar->entry_bytes_remaining +
            tar->entry_padding);
        if (bytes_skipped < 0)
                return (ARCHIVE_FATAL);

        tar->entry_bytes_remaining = 0;
        tar->entry_padding = 0;

        /* Free the sparse list. */
        while (tar->sparse_list != NULL) {
                p = tar->sparse_list;
                tar->sparse_list = p->next;
                free(p);
        }

        return (ARCHIVE_OK);
}

/*
 * This function recursively interprets all of the headers associated
 * with a single entry.
 */
static int
tar_read_header(struct archive_read *a, struct tar *tar,
    struct archive_entry *entry, struct stat *st)
{
        ssize_t bytes;
        int err;
        const void *h;
        const struct archive_entry_header_ustar *header;

        /* Read 512-byte header record */
        bytes = (a->compression_read_ahead)(a, &h, 512);
        if (bytes < 512) {
                /*
                 * If we're here, it's becase the _bid function accepted
                 * this file.  So just call a short read end-of-archive
                 * and be done with it.
                 */
                return (ARCHIVE_EOF);
        }
        (a->compression_read_consume)(a, 512);

        /* Check for end-of-archive mark. */
        if (((*(const char *)h)==0) && archive_block_is_null((const unsigned char *)h)) {
                /* Try to consume a second all-null record, as well. */
                bytes = (a->compression_read_ahead)(a, &h, 512);
                if (bytes > 0)
                        (a->compression_read_consume)(a, bytes);
                archive_set_error(&a->archive, 0, NULL);
                return (ARCHIVE_EOF);
        }

        /*
         * Note: If the checksum fails and we return ARCHIVE_RETRY,
         * then the client is likely to just retry.  This is a very
         * crude way to search for the next valid header!
         *
         * TODO: Improve this by implementing a real header scan.
         */
        if (!checksum(a, h)) {
                archive_set_error(&a->archive, EINVAL, "Damaged tar archive");
                return (ARCHIVE_RETRY); /* Retryable: Invalid header */
        }

        if (++tar->header_recursion_depth > 32) {
                archive_set_error(&a->archive, EINVAL, "Too many special headers");
                return (ARCHIVE_WARN);
        }

        /* Determine the format variant. */
        header = (const struct archive_entry_header_ustar *)h;
        switch(header->typeflag[0]) {
        case 'A': /* Solaris tar ACL */
                a->archive.archive_format = ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE;
                a->archive.archive_format_name = "Solaris tar";
                err = header_Solaris_ACL(a, tar, entry, st, h);
                break;
        case 'g': /* POSIX-standard 'g' header. */
                a->archive.archive_format = ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE;
                a->archive.archive_format_name = "POSIX pax interchange format";
                err = header_pax_global(a, tar, entry, st, h);
                break;
        case 'K': /* Long link name (GNU tar, others) */
                err = header_longlink(a, tar, entry, st, h);
                break;
        case 'L': /* Long filename (GNU tar, others) */
                err = header_longname(a, tar, entry, st, h);
                break;
        case 'V': /* GNU volume header */
                err = header_volume(a, tar, entry, st, h);
                break;
        case 'X': /* Used by SUN tar; same as 'x'. */
                a->archive.archive_format = ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE;
                a->archive.archive_format_name =
                    "POSIX pax interchange format (Sun variant)";
                err = header_pax_extensions(a, tar, entry, st, h);
                break;
        case 'x': /* POSIX-standard 'x' header. */
                a->archive.archive_format = ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE;
                a->archive.archive_format_name = "POSIX pax interchange format";
                err = header_pax_extensions(a, tar, entry, st, h);
                break;
        default:
                if (memcmp(header->magic, "ustar  \0", 8) == 0) {
                        a->archive.archive_format = ARCHIVE_FORMAT_TAR_GNUTAR;
                        a->archive.archive_format_name = "GNU tar format";
                        err = header_gnutar(a, tar, entry, st, h);
                } else if (memcmp(header->magic, "ustar", 5) == 0) {
                        if (a->archive.archive_format != ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE) {
                                a->archive.archive_format = ARCHIVE_FORMAT_TAR_USTAR;
                                a->archive.archive_format_name = "POSIX ustar format";
                        }
                        err = header_ustar(a, tar, entry, st, h);
                } else {
                        a->archive.archive_format = ARCHIVE_FORMAT_TAR;
                        a->archive.archive_format_name = "tar (non-POSIX)";
                        err = header_old_tar(a, tar, entry, st, h);
                }
        }
        --tar->header_recursion_depth;
        return (err);
}

/*
 * Return true if block checksum is correct.
 */
static int
checksum(struct archive_read *a, const void *h)
{
        const unsigned char *bytes;
        const struct archive_entry_header_ustar *header;
        int check, i, sum;

        (void)a; /* UNUSED */
        bytes = (const unsigned char *)h;
        header = (const struct archive_entry_header_ustar *)h;

        /*
         * Test the checksum.  Note that POSIX specifies _unsigned_
         * bytes for this calculation.
         */
        sum = tar_atol(header->checksum, sizeof(header->checksum));
        check = 0;
        for (i = 0; i < 148; i++)
                check += (unsigned char)bytes[i];
        for (; i < 156; i++)
                check += 32;
        for (; i < 512; i++)
                check += (unsigned char)bytes[i];
        if (sum == check)
                return (1);

        /*
         * Repeat test with _signed_ bytes, just in case this archive
         * was created by an old BSD, Solaris, or HP-UX tar with a
         * broken checksum calculation.
         */
        check = 0;
        for (i = 0; i < 148; i++)
                check += (signed char)bytes[i];
        for (; i < 156; i++)
                check += 32;
        for (; i < 512; i++)
                check += (signed char)bytes[i];
        if (sum == check)
                return (1);

        return (0);
}

/*
 * Return true if this block contains only nulls.
 */
static int
archive_block_is_null(const unsigned char *p)
{
        unsigned i;

        for (i = 0; i < ARCHIVE_BYTES_PER_RECORD / sizeof(*p); i++)
                if (*p++)
                        return (0);
        return (1);
}

/*
 * Interpret 'A' Solaris ACL header
 */
static int
header_Solaris_ACL(struct archive_read *a, struct tar *tar,
    struct archive_entry *entry, struct stat *st, const void *h)
{
        int err, err2;
        char *p;
        wchar_t *wp;

        err = read_body_to_string(a, tar, &(tar->acl_text), h);
        err2 = tar_read_header(a, tar, entry, st);
        err = err_combine(err, err2);

        /* XXX Ensure p doesn't overrun acl_text */

        /* Skip leading octal number. */
        /* XXX TODO: Parse the octal number and sanity-check it. */
        p = tar->acl_text.s;
        while (*p != '\0')
                p++;
        p++;

        wp = (wchar_t *)malloc((strlen(p) + 1) * sizeof(wchar_t));
        if (wp != NULL) {
                utf8_decode(wp, p, strlen(p));
                err2 = __archive_entry_acl_parse_w(entry, wp,
                    ARCHIVE_ENTRY_ACL_TYPE_ACCESS);
                err = err_combine(err, err2);
                free(wp);
        }

        return (err);
}

/*
 * Interpret 'K' long linkname header.
 */
static int
header_longlink(struct archive_read *a, struct tar *tar,
    struct archive_entry *entry, struct stat *st, const void *h)
{
        int err, err2;

        err = read_body_to_string(a, tar, &(tar->longlink), h);
        err2 = tar_read_header(a, tar, entry, st);
        if (err == ARCHIVE_OK && err2 == ARCHIVE_OK) {
                /* Set symlink if symlink already set, else hardlink. */
                archive_entry_set_link(entry, tar->longlink.s);
        }
        return (err_combine(err, err2));
}

/*
 * Interpret 'L' long filename header.
 */
static int
header_longname(struct archive_read *a, struct tar *tar,
    struct archive_entry *entry, struct stat *st, const void *h)
{
        int err, err2;

        err = read_body_to_string(a, tar, &(tar->longname), h);
        /* Read and parse "real" header, then override name. */
        err2 = tar_read_header(a, tar, entry, st);
        if (err == ARCHIVE_OK && err2 == ARCHIVE_OK)
                archive_entry_set_pathname(entry, tar->longname.s);
        return (err_combine(err, err2));
}


/*
 * Interpret 'V' GNU tar volume header.
 */
static int
header_volume(struct archive_read *a, struct tar *tar,
    struct archive_entry *entry, struct stat *st, const void *h)
{
        (void)h;

        /* Just skip this and read the next header. */
        return (tar_read_header(a, tar, entry, st));
}

/*
 * Read body of an archive entry into an archive_string object.
 */
static int
read_body_to_string(struct archive_read *a, struct tar *tar,
    struct archive_string *as, const void *h)
{
        off_t size, padded_size;
        ssize_t bytes_read, bytes_to_copy;
        const struct archive_entry_header_ustar *header;
        const void *src;
        char *dest;

        (void)tar; /* UNUSED */
        header = (const struct archive_entry_header_ustar *)h;
        size  = tar_atol(header->size, sizeof(header->size));

        /* Read the body into the string. */
        archive_string_ensure(as, size+1);
        padded_size = (size + 511) & ~ 511;
        dest = as->s;
        while (padded_size > 0) {
                bytes_read = (a->compression_read_ahead)(a, &src, padded_size);
                if (bytes_read < 0)
                        return (ARCHIVE_FATAL);
                if (bytes_read > padded_size)
                        bytes_read = padded_size;
                (a->compression_read_consume)(a, bytes_read);
                bytes_to_copy = bytes_read;
                if ((off_t)bytes_to_copy > size)
                        bytes_to_copy = (ssize_t)size;
                memcpy(dest, src, bytes_to_copy);
                dest += bytes_to_copy;
                size -= bytes_to_copy;
                padded_size -= bytes_read;
        }
        *dest = '\0';
        return (ARCHIVE_OK);
}

/*
 * Parse out common header elements.
 *
 * This would be the same as header_old_tar, except that the
 * filename is handled slightly differently for old and POSIX
 * entries  (POSIX entries support a 'prefix').  This factoring
 * allows header_old_tar and header_ustar
 * to handle filenames differently, while still putting most of the
 * common parsing into one place.
 */
static int
header_common(struct archive_read *a, struct tar *tar, struct archive_entry *entry,
    struct stat *st, const void *h)
{
        const struct archive_entry_header_ustar *header;
        char    tartype;

        (void)a; /* UNUSED */

        header = (const struct archive_entry_header_ustar *)h;
        if (header->linkname[0])
                archive_strncpy(&(tar->entry_linkname), header->linkname,
                    sizeof(header->linkname));
        else
                archive_string_empty(&(tar->entry_linkname));

        /* Parse out the numeric fields (all are octal) */
        st->st_mode  = tar_atol(header->mode, sizeof(header->mode));
        st->st_uid   = tar_atol(header->uid, sizeof(header->uid));
        st->st_gid   = tar_atol(header->gid, sizeof(header->gid));
        st->st_size  = tar_atol(header->size, sizeof(header->size));
        st->st_mtime = tar_atol(header->mtime, sizeof(header->mtime));

        /* Handle the tar type flag appropriately. */
        tartype = header->typeflag[0];
        st->st_mode &= ~S_IFMT;

        switch (tartype) {
        case '1': /* Hard link */
                archive_entry_set_hardlink(entry, tar->entry_linkname.s);
                /*
                 * The following may seem odd, but: Technically, tar
                 * does not store the file type for a "hard link"
                 * entry, only the fact that it is a hard link.  So, I
                 * leave the type zero normally.  But, pax interchange
                 * format allows hard links to have data, which
                 * implies that the underlying entry is a regular
                 * file.
                 */
                if (st->st_size > 0)
                        st->st_mode |= S_IFREG;

                /*
                 * A tricky point: Traditionally, tar readers have
                 * ignored the size field when reading hardlink
                 * entries, and some writers put non-zero sizes even
                 * though the body is empty.  POSIX.1-2001 broke with
                 * this tradition by permitting hardlink entries to
                 * store valid bodies in pax interchange format, but
                 * not in ustar format.  Since there is no hard and
                 * fast way to distinguish pax interchange from
                 * earlier archives (the 'x' and 'g' entries are
                 * optional, after all), we need a heuristic.  Here, I
                 * use the bid function to test whether or not there's
                 * a valid header following.  Of course, if we know
                 * this is pax interchange format, then we must obey
                 * the size.
                 *
                 * This heuristic will only fail for a pax interchange
                 * archive that is storing hardlink bodies, no pax
                 * extended attribute entries have yet occurred, and
                 * we encounter a hardlink entry for a file that is
                 * itself an uncompressed tar archive.
                 */
                if (st->st_size > 0  &&
                    a->archive.archive_format != ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE  &&
                    archive_read_format_tar_bid(a) > 50)
                        st->st_size = 0;
                break;
        case '2': /* Symlink */
                st->st_mode |= S_IFLNK;
                st->st_size = 0;
                archive_entry_set_symlink(entry, tar->entry_linkname.s);
                break;
        case '3': /* Character device */
                st->st_mode |= S_IFCHR;
                st->st_size = 0;
                break;
        case '4': /* Block device */
                st->st_mode |= S_IFBLK;
                st->st_size = 0;
                break;
        case '5': /* Dir */
                st->st_mode |= S_IFDIR;
                st->st_size = 0;
                break;
        case '6': /* FIFO device */
                st->st_mode |= S_IFIFO;
                st->st_size = 0;
                break;
        case 'D': /* GNU incremental directory type */
                /*
                 * No special handling is actually required here.
                 * It might be nice someday to preprocess the file list and
                 * provide it to the client, though.
                 */
                st->st_mode |= S_IFDIR;
                break;
        case 'M': /* GNU "Multi-volume" (remainder of file from last archive)*/
                /*
                 * As far as I can tell, this is just like a regular file
                 * entry, except that the contents should be _appended_ to
                 * the indicated file at the indicated offset.  This may
                 * require some API work to fully support.
                 */
                break;
        case 'N': /* Old GNU "long filename" entry. */
                /* The body of this entry is a script for renaming
                 * previously-extracted entries.  Ugh.  It will never
                 * be supported by libarchive. */
                st->st_mode |= S_IFREG;
                break;
        case 'S': /* GNU sparse files */
                /*
                 * Sparse files are really just regular files with
                 * sparse information in the extended area.
                 */
                /* FALL THROUGH */
        default: /* Regular file  and non-standard types */
                /*
                 * Per POSIX: non-recognized types should always be
                 * treated as regular files.
                 */
                st->st_mode |= S_IFREG;
                break;
        }
        return (0);
}

/*
 * Parse out header elements for "old-style" tar archives.
 */
static int
header_old_tar(struct archive_read *a, struct tar *tar, struct archive_entry *entry,
    struct stat *st, const void *h)
{
        const struct archive_entry_header_ustar *header;

        /* Copy filename over (to ensure null termination). */
        header = (const struct archive_entry_header_ustar *)h;
        archive_strncpy(&(tar->entry_name), header->name, sizeof(header->name));
        archive_entry_set_pathname(entry, tar->entry_name.s);

        /* Grab rest of common fields */
        header_common(a, tar, entry, st, h);

        tar->entry_bytes_remaining = st->st_size;
        tar->entry_padding = 0x1ff & (-tar->entry_bytes_remaining);
        return (0);
}

/*
 * Parse a file header for a pax extended archive entry.
 */
static int
header_pax_global(struct archive_read *a, struct tar *tar,
    struct archive_entry *entry, struct stat *st, const void *h)
{
        int err, err2;

        err = read_body_to_string(a, tar, &(tar->pax_global), h);
        err2 = tar_read_header(a, tar, entry, st);
        return (err_combine(err, err2));
}

static int
header_pax_extensions(struct archive_read *a, struct tar *tar,
    struct archive_entry *entry, struct stat *st, const void *h)
{
        int err, err2;

        read_body_to_string(a, tar, &(tar->pax_header), h);

        /* Parse the next header. */
        err = tar_read_header(a, tar, entry, st);

        /*
         * TODO: Parse global/default options into 'entry' struct here
         * before handling file-specific options.
         *
         * This design (parse standard header, then overwrite with pax
         * extended attribute data) usually works well, but isn't ideal;
         * it would be better to parse the pax extended attributes first
         * and then skip any fields in the standard header that were
         * defined in the pax header.
         */
        err2 = pax_header(a, tar, entry, st, tar->pax_header.s);
        err =  err_combine(err, err2);
        tar->entry_bytes_remaining = st->st_size;
        tar->entry_padding = 0x1ff & (-tar->entry_bytes_remaining);
        return (err);
}


/*
 * Parse a file header for a Posix "ustar" archive entry.  This also
 * handles "pax" or "extended ustar" entries.
 */
static int
header_ustar(struct archive_read *a, struct tar *tar, struct archive_entry *entry,
    struct stat *st, const void *h)
{
        const struct archive_entry_header_ustar *header;
        struct archive_string *as;

        header = (const struct archive_entry_header_ustar *)h;

        /* Copy name into an internal buffer to ensure null-termination. */
        as = &(tar->entry_name);
        if (header->prefix[0]) {
                archive_strncpy(as, header->prefix, sizeof(header->prefix));
                if (as->s[archive_strlen(as) - 1] != '/')
                        archive_strappend_char(as, '/');
                archive_strncat(as, header->name, sizeof(header->name));
        } else
                archive_strncpy(as, header->name, sizeof(header->name));

        archive_entry_set_pathname(entry, as->s);

        /* Handle rest of common fields. */
        header_common(a, tar, entry, st, h);

        /* Handle POSIX ustar fields. */
        archive_strncpy(&(tar->entry_uname), header->uname,
            sizeof(header->uname));
        archive_entry_set_uname(entry, tar->entry_uname.s);

        archive_strncpy(&(tar->entry_gname), header->gname,
            sizeof(header->gname));
        archive_entry_set_gname(entry, tar->entry_gname.s);

        /* Parse out device numbers only for char and block specials. */
        if (header->typeflag[0] == '3' || header->typeflag[0] == '4') {
                st->st_rdev = makedev(
                    tar_atol(header->rdevmajor, sizeof(header->rdevmajor)),
                    tar_atol(header->rdevminor, sizeof(header->rdevminor)));
        }

        tar->entry_bytes_remaining = st->st_size;
        tar->entry_padding = 0x1ff & (-tar->entry_bytes_remaining);

        return (0);
}


/*
 * Parse the pax extended attributes record.
 *
 * Returns non-zero if there's an error in the data.
 */
static int
pax_header(struct archive_read *a, struct tar *tar, struct archive_entry *entry,
    struct stat *st, char *attr)
{
        size_t attr_length, l, line_length;
        char *line, *p;
        wchar_t *key, *wp, *value;
        int err, err2;

        attr_length = strlen(attr);
        err = ARCHIVE_OK;
        while (attr_length > 0) {
                /* Parse decimal length field at start of line. */
                line_length = 0;
                l = attr_length;
                line = p = attr; /* Record start of line. */
                while (l>0) {
                        if (*p == ' ') {
                                p++;
                                l--;
                                break;
                        }
                        if (*p < '0' || *p > '9')
                                return (-1);
                        line_length *= 10;
                        line_length += *p - '0';
                        if (line_length > 999999) {
                                archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                                    "Rejecting pax extended attribute > 1MB");
                                return (ARCHIVE_WARN);
                        }
                        p++;
                        l--;
                }

                if (line_length > attr_length)
                        return (0);

                /* Ensure pax_entry buffer is big enough. */
                if (tar->pax_entry_length <= line_length) {
                        wchar_t *old_entry = tar->pax_entry;

                        if (tar->pax_entry_length <= 0)
                                tar->pax_entry_length = 1024;
                        while (tar->pax_entry_length <= line_length + 1)
                                tar->pax_entry_length *= 2;

                        old_entry = tar->pax_entry;
                        tar->pax_entry = (wchar_t *)realloc(tar->pax_entry,
                            tar->pax_entry_length * sizeof(wchar_t));
                        if (tar->pax_entry == NULL) {
                                free(old_entry);
                                archive_set_error(&a->archive, ENOMEM,
                                        "No memory");
                                return (ARCHIVE_FATAL);
                        }
                }

                /* Decode UTF-8 to wchar_t, null-terminate result. */
                if (utf8_decode(tar->pax_entry, p,
                        line_length - (p - attr) - 1)) {
                        archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                           "Invalid UTF8 character in pax extended attribute");
                        err = err_combine(err, ARCHIVE_WARN);
                }

                /* Null-terminate 'key' value. */
                wp = key = tar->pax_entry;
                if (key[0] == L'=')
                        return (-1);
                while (*wp && *wp != L'=')
                        ++wp;
                if (*wp == L'\0' || wp == NULL) {
                        archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                            "Invalid pax extended attributes");
                        return (ARCHIVE_WARN);
                }
                *wp = 0;

                /* Identify null-terminated 'value' portion. */
                value = wp + 1;

                /* Identify this attribute and set it in the entry. */
                err2 = pax_attribute(entry, st, key, value);
                err = err_combine(err, err2);

                /* Skip to next line */
                attr += line_length;
                attr_length -= line_length;
        }
        return (err);
}

static int
pax_attribute_xattr(struct archive_entry *entry,
        wchar_t *name, wchar_t *value)
{
        char *name_decoded, *name_narrow;
        void *value_decoded;
        size_t value_len;

        if (wcslen(name) < 18 || (wcsncmp(name, L"LIBARCHIVE.xattr.", 17)) != 0)
                return 3;

        name += 17;

        /* URL-decode name */
        name_narrow = wide_to_narrow(name);
        if (name_narrow == NULL)
                return 2;
        name_decoded = url_decode(name_narrow);
        free(name_narrow);
        if (name_decoded == NULL)
                return 2;

        /* Base-64 decode value */
        value_decoded = base64_decode(value, wcslen(value), &value_len);
        if (value_decoded == NULL) {
                free(name_decoded);
                return 1;
        }

        archive_entry_xattr_add_entry(entry, name_decoded,
                value_decoded, value_len);

        free(name_decoded);
        free(value_decoded);
        return 0;
}

/*
 * Parse a single key=value attribute.  key/value pointers are
 * assumed to point into reasonably long-lived storage.
 *
 * Note that POSIX reserves all-lowercase keywords.  Vendor-specific
 * extensions should always have keywords of the form "VENDOR.attribute"
 * In particular, it's quite feasible to support many different
 * vendor extensions here.  I'm using "LIBARCHIVE" for extensions
 * unique to this library (currently, there are none).
 *
 * Investigate other vendor-specific extensions, as well and see if
 * any of them look useful.
 */
static int
pax_attribute(struct archive_entry *entry, struct stat *st,
    wchar_t *key, wchar_t *value)
{
        int64_t s;
        long n;

        switch (key[0]) {
        case 'L':
                /* Our extensions */
/* TODO: Handle arbitrary extended attributes... */
/*
                if (strcmp(key, "LIBARCHIVE.xxxxxxx")==0)
                        archive_entry_set_xxxxxx(entry, value);
*/
                if (wcsncmp(key, L"LIBARCHIVE.xattr.", 17)==0)
                        pax_attribute_xattr(entry, key, value);
                break;
        case 'S':
                /* We support some keys used by the "star" archiver */
                if (wcscmp(key, L"SCHILY.acl.access")==0)
                        __archive_entry_acl_parse_w(entry, value,
                            ARCHIVE_ENTRY_ACL_TYPE_ACCESS);
                else if (wcscmp(key, L"SCHILY.acl.default")==0)
                        __archive_entry_acl_parse_w(entry, value,
                            ARCHIVE_ENTRY_ACL_TYPE_DEFAULT);
                else if (wcscmp(key, L"SCHILY.devmajor")==0)
                        st->st_rdev = makedev(tar_atol10(value, wcslen(value)),
                            minor(st->st_rdev));
                else if (wcscmp(key, L"SCHILY.devminor")==0)
                        st->st_rdev = makedev(major(st->st_rdev),
                            tar_atol10(value, wcslen(value)));
                else if (wcscmp(key, L"SCHILY.fflags")==0)
                        archive_entry_copy_fflags_text_w(entry, value);
                else if (wcscmp(key, L"SCHILY.dev")==0)
                        st->st_dev = tar_atol10(value, wcslen(value));
                else if (wcscmp(key, L"SCHILY.ino")==0)
                        st->st_ino = tar_atol10(value, wcslen(value));
                else if (wcscmp(key, L"SCHILY.nlink")==0)
                        st->st_nlink = tar_atol10(value, wcslen(value));
                break;
        case 'a':
                if (wcscmp(key, L"atime")==0) {
                        pax_time(value, &s, &n);
                        st->st_atime = s;
                        ARCHIVE_STAT_SET_ATIME_NANOS(st, n);
                }
                break;
        case 'c':
                if (wcscmp(key, L"ctime")==0) {
                        pax_time(value, &s, &n);
                        st->st_ctime = s;
                        ARCHIVE_STAT_SET_CTIME_NANOS(st, n);
                } else if (wcscmp(key, L"charset")==0) {
                        /* TODO: Publish charset information in entry. */
                } else if (wcscmp(key, L"comment")==0) {
                        /* TODO: Publish comment in entry. */
                }
                break;
        case 'g':
                if (wcscmp(key, L"gid")==0)
                        st->st_gid = tar_atol10(value, wcslen(value));
                else if (wcscmp(key, L"gname")==0)
                        archive_entry_copy_gname_w(entry, value);
                break;
        case 'l':
                /* pax interchange doesn't distinguish hardlink vs. symlink. */
                if (wcscmp(key, L"linkpath")==0) {
                        if (archive_entry_hardlink(entry))
                                archive_entry_copy_hardlink_w(entry, value);
                        else
                                archive_entry_copy_symlink_w(entry, value);
                }
                break;
        case 'm':
                if (wcscmp(key, L"mtime")==0) {
                        pax_time(value, &s, &n);
                        st->st_mtime = s;
                        ARCHIVE_STAT_SET_MTIME_NANOS(st, n);
                }
                break;
        case 'p':
                if (wcscmp(key, L"path")==0)
                        archive_entry_copy_pathname_w(entry, value);
                break;
        case 'r':
                /* POSIX has reserved 'realtime.*' */
                break;
        case 's':
                /* POSIX has reserved 'security.*' */
                /* Someday: if (wcscmp(key, L"security.acl")==0) { ... } */
                if (wcscmp(key, L"size")==0)
                        st->st_size = tar_atol10(value, wcslen(value));
                break;
        case 'u':
                if (wcscmp(key, L"uid")==0)
                        st->st_uid = tar_atol10(value, wcslen(value));
                else if (wcscmp(key, L"uname")==0)
                        archive_entry_copy_uname_w(entry, value);
                break;
        }
        return (0);
}



/*
 * parse a decimal time value, which may include a fractional portion
 */
static void
pax_time(const wchar_t *p, int64_t *ps, long *pn)
{
        char digit;
        int64_t s;
        unsigned long l;
        int sign;
        int64_t limit, last_digit_limit;

        limit = max_int64 / 10;
        last_digit_limit = max_int64 % 10;

        s = 0;
        sign = 1;
        if (*p == '-') {
                sign = -1;
                p++;
        }
        while (*p >= '0' && *p <= '9') {
                digit = *p - '0';
                if (s > limit ||
                    (s == limit && digit > last_digit_limit)) {
                        s = max_uint64;
                        break;
                }
                s = (s * 10) + digit;
                ++p;
        }

        *ps = s * sign;

        /* Calculate nanoseconds. */
        *pn = 0;

        if (*p != '.')
                return;

        l = 100000000UL;
        do {
                ++p;
                if (*p >= '0' && *p <= '9')
                        *pn += (*p - '0') * l;
                else
                        break;
        } while (l /= 10);
}

/*
 * Parse GNU tar header
 */
static int
header_gnutar(struct archive_read *a, struct tar *tar, struct archive_entry *entry,
    struct stat *st, const void *h)
{
        const struct archive_entry_header_gnutar *header;

        (void)a;

        /*
         * GNU header is like POSIX ustar, except 'prefix' is
         * replaced with some other fields. This also means the
         * filename is stored as in old-style archives.
         */

        /* Grab fields common to all tar variants. */
        header_common(a, tar, entry, st, h);

        /* Copy filename over (to ensure null termination). */
        header = (const struct archive_entry_header_gnutar *)h;
        archive_strncpy(&(tar->entry_name), header->name,
            sizeof(header->name));
        archive_entry_set_pathname(entry, tar->entry_name.s);

        /* Fields common to ustar and GNU */
        /* XXX Can the following be factored out since it's common
         * to ustar and gnu tar?  Is it okay to move it down into
         * header_common, perhaps?  */
        archive_strncpy(&(tar->entry_uname),
            header->uname, sizeof(header->uname));
        archive_entry_set_uname(entry, tar->entry_uname.s);

        archive_strncpy(&(tar->entry_gname),
            header->gname, sizeof(header->gname));
        archive_entry_set_gname(entry, tar->entry_gname.s);

        /* Parse out device numbers only for char and block specials */
        if (header->typeflag[0] == '3' || header->typeflag[0] == '4')
                st->st_rdev = makedev (
                    tar_atol(header->rdevmajor, sizeof(header->rdevmajor)),
                    tar_atol(header->rdevminor, sizeof(header->rdevminor)));
        else
                st->st_rdev = 0;

        tar->entry_bytes_remaining = st->st_size;
        tar->entry_padding = 0x1ff & (-tar->entry_bytes_remaining);

        /* Grab GNU-specific fields. */
        st->st_atime = tar_atol(header->atime, sizeof(header->atime));
        st->st_ctime = tar_atol(header->ctime, sizeof(header->ctime));
        if (header->realsize[0] != 0) {
                st->st_size = tar_atol(header->realsize,
                    sizeof(header->realsize));
        }

        if (header->sparse[0].offset[0] != 0) {
                gnu_read_sparse_data(a, tar, header);
        } else {
                if (header->isextended[0] != 0) {
                        /* XXX WTF? XXX */
                }
        }

        return (0);
}

static int
gnu_read_sparse_data(struct archive_read *a, struct tar *tar,
    const struct archive_entry_header_gnutar *header)
{
        ssize_t bytes_read;
        const void *data;
        struct extended {
                struct gnu_sparse sparse[21];
                char    isextended[1];
                char    padding[7];
        };
        const struct extended *ext;

        gnu_parse_sparse_data(a, tar, header->sparse, 4);
        if (header->isextended[0] == 0)
                return (ARCHIVE_OK);

        do {
                bytes_read = (a->compression_read_ahead)(a, &data, 512);
                if (bytes_read < 0)
                        return (ARCHIVE_FATAL);
                if (bytes_read < 512) {
                        archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
                            "Truncated tar archive "
                            "detected while reading sparse file data");
                        return (ARCHIVE_FATAL);
                }
                (a->compression_read_consume)(a, 512);
                ext = (const struct extended *)data;
                gnu_parse_sparse_data(a, tar, ext->sparse, 21);
        } while (ext->isextended[0] != 0);
        if (tar->sparse_list != NULL)
                tar->entry_offset = tar->sparse_list->offset;
        return (ARCHIVE_OK);
}

static void
gnu_parse_sparse_data(struct archive_read *a, struct tar *tar,
    const struct gnu_sparse *sparse, int length)
{
        struct sparse_block *last;
        struct sparse_block *p;

        (void)a; /* UNUSED */

        last = tar->sparse_list;
        while (last != NULL && last->next != NULL)
                last = last->next;

        while (length > 0 && sparse->offset[0] != 0) {
                p = (struct sparse_block *)malloc(sizeof(*p));
                if (p == NULL)
                        __archive_errx(1, "Out of memory");
                memset(p, 0, sizeof(*p));
                if (last != NULL)
                        last->next = p;
                else
                        tar->sparse_list = p;
                last = p;
                p->offset = tar_atol(sparse->offset, sizeof(sparse->offset));
                p->remaining =
                    tar_atol(sparse->numbytes, sizeof(sparse->numbytes));
                sparse++;
                length--;
        }
}

/*-
 * Convert text->integer.
 *
 * Traditional tar formats (including POSIX) specify base-8 for
 * all of the standard numeric fields.  This is a significant limitation
 * in practice:
 *   = file size is limited to 8GB
 *   = rdevmajor and rdevminor are limited to 21 bits
 *   = uid/gid are limited to 21 bits
 *
 * There are two workarounds for this:
 *   = pax extended headers, which use variable-length string fields
 *   = GNU tar and STAR both allow either base-8 or base-256 in
 *      most fields.  The high bit is set to indicate base-256.
 *
 * On read, this implementation supports both extensions.
 */
static int64_t
tar_atol(const char *p, unsigned char_cnt)
{
        /*
         * Technically, GNU tar considers a field to be in base-256
         * only if the first byte is 0xff or 0x80.
         */
        if (*p & 0x80)
                return (tar_atol256(p, char_cnt));
        return (tar_atol8(p, char_cnt));
}

/*
 * Note that this implementation does not (and should not!) obey
 * locale settings; you cannot simply substitute strtol here, since
 * it does obey locale.
 */
static int64_t
tar_atol8(const char *p, unsigned char_cnt)
{
        int64_t l, limit, last_digit_limit;
        int digit, sign, base;

        base = 8;
        limit = max_int64 / base;
        last_digit_limit = max_int64 % base;

        while (*p == ' ' || *p == '\t')
                p++;
        if (*p == '-') {
                sign = -1;
                p++;
        } else
                sign = 1;

        l = 0;
        digit = *p - '0';
        while (digit >= 0 && digit < base  && char_cnt-- > 0) {
                if (l>limit || (l == limit && digit > last_digit_limit)) {
                        l = max_uint64; /* Truncate on overflow. */
                        break;
                }
                l = (l * base) + digit;
                digit = *++p - '0';
        }
        return (sign < 0) ? -l : l;
}


/*
 * Note that this implementation does not (and should not!) obey
 * locale settings; you cannot simply substitute strtol here, since
 * it does obey locale.
 */
static int64_t
tar_atol10(const wchar_t *p, unsigned char_cnt)
{
        int64_t l, limit, last_digit_limit;
        int base, digit, sign;

        base = 10;
        limit = max_int64 / base;
        last_digit_limit = max_int64 % base;

        while (*p == ' ' || *p == '\t')
                p++;
        if (*p == '-') {
                sign = -1;
                p++;
        } else
                sign = 1;

        l = 0;
        digit = *p - '0';
        while (digit >= 0 && digit < base  && char_cnt-- > 0) {
                if (l > limit || (l == limit && digit > last_digit_limit)) {
                        l = max_uint64; /* Truncate on overflow. */
                        break;
                }
                l = (l * base) + digit;
                digit = *++p - '0';
        }
        return (sign < 0) ? -l : l;
}

/*
 * Parse a base-256 integer.  This is just a straight signed binary
 * value in big-endian order, except that the high-order bit is
 * ignored.  Remember that "int64_t" may or may not be exactly 64
 * bits; the implementation here tries to avoid making any assumptions
 * about the actual size of an int64_t.  It does assume we're using
 * twos-complement arithmetic, though.
 */
static int64_t
tar_atol256(const char *_p, unsigned char_cnt)
{
        int64_t l, upper_limit, lower_limit;
        const unsigned char *p = (const unsigned char *)_p;

        upper_limit = max_int64 / 256;
        lower_limit = min_int64 / 256;

        /* Pad with 1 or 0 bits, depending on sign. */
        if ((0x40 & *p) == 0x40)
                l = (int64_t)-1;
        else
                l = 0;
        l = (l << 6) | (0x3f & *p++);
        while (--char_cnt > 0) {
                if (l > upper_limit) {
                        l = max_int64; /* Truncate on overflow */
                        break;
                } else if (l < lower_limit) {
                        l = min_int64;
                        break;
                }
                l = (l << 8) | (0xff & (int64_t)*p++);
        }
        return (l);
}

static int
utf8_decode(wchar_t *dest, const char *src, size_t length)
{
        size_t n;
        int err;

        err = 0;
        while (length > 0) {
                n = UTF8_mbrtowc(dest, src, length);
                if (n == 0)
                        break;
                dest++;
                src += n;
                length -= n;
        }
        *dest++ = L'\0';
        return (err);
}

/*
 * Copied and simplified from FreeBSD libc/locale.
 */
static size_t
UTF8_mbrtowc(wchar_t *pwc, const char *s, size_t n)
{
        int ch, i, len, mask;
        unsigned long wch;

        if (s == NULL || n == 0 || pwc == NULL)
                return (0);

        /*
         * Determine the number of octets that make up this character from
         * the first octet, and a mask that extracts the interesting bits of
         * the first octet.
         */
        ch = (unsigned char)*s;
        if ((ch & 0x80) == 0) {
                mask = 0x7f;
                len = 1;
        } else if ((ch & 0xe0) == 0xc0) {
                mask = 0x1f;
                len = 2;
        } else if ((ch & 0xf0) == 0xe0) {
                mask = 0x0f;
                len = 3;
        } else if ((ch & 0xf8) == 0xf0) {
                mask = 0x07;
                len = 4;
        } else if ((ch & 0xfc) == 0xf8) {
                mask = 0x03;
                len = 5;
        } else if ((ch & 0xfe) == 0xfc) {
                mask = 0x01;
                len = 6;
        } else {
                /* Invalid first byte; convert to '?' */
                *pwc = '?';
                return (1);
        }

        if (n < (size_t)len) {
                /* Invalid first byte; convert to '?' */
                *pwc = '?';
                return (1);
        }

        /*
         * Decode the octet sequence representing the character in chunks
         * of 6 bits, most significant first.
         */
        wch = (unsigned char)*s++ & mask;
        i = len;
        while (--i != 0) {
                if ((*s & 0xc0) != 0x80) {
                        /* Invalid intermediate byte; consume one byte and
                         * emit '?' */
                        *pwc = '?';
                        return (1);
                }
                wch <<= 6;
                wch |= *s++ & 0x3f;
        }

        /* Assign the value to the output; out-of-range values
         * just get truncated. */
        *pwc = (wchar_t)wch;
#ifdef WCHAR_MAX
        /*
         * If platform has WCHAR_MAX, we can do something
         * more sensible with out-of-range values.
         */
        if (wch >= WCHAR_MAX)
                *pwc = '?';
#endif
        /* Return number of bytes input consumed: 0 for end-of-string. */
        return (wch == L'\0' ? 0 : len);
}


/*
 * base64_decode - Base64 decode
 *
 * This accepts most variations of base-64 encoding, including:
 *    * with or without line breaks
 *    * with or without the final group padded with '=' or '_' characters
 * (The most economical Base-64 variant does not pad the last group and
 * omits line breaks; RFC1341 used for MIME requires both.)
 */
static char *
base64_decode(const wchar_t *src, size_t len, size_t *out_len)
{
        static const unsigned 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','+','/' };
        static unsigned char decode_table[128];
        char *out, *d;

        /* If the decode table is not yet initialized, prepare it. */
        if (decode_table[digits[1]] != 1) {
                size_t i;
                memset(decode_table, 0xff, sizeof(decode_table));
                for (i = 0; i < sizeof(digits); i++)
                        decode_table[digits[i]] = i;
        }

        /* Allocate enough space to hold the entire output. */
        /* Note that we may not use all of this... */
        out = (char *)malloc((len * 3 + 3) / 4);
        if (out == NULL) {
                *out_len = 0;
                return (NULL);
        }
        d = out;

        while (len > 0) {
                /* Collect the next group of (up to) four characters. */
                int v = 0;
                int group_size = 0;
                while (group_size < 4 && len > 0) {
                        /* '=' or '_' padding indicates final group. */
                        if (*src == '=' || *src == '_') {
                                len = 0;
                                break;
                        }
                        /* Skip illegal characters (including line breaks) */
                        if (*src > 127 || *src < 32
                            || decode_table[*src] == 0xff) {
                                len--;
                                src++;
                                continue;
                        }
                        v <<= 6;
                        v |= decode_table[*src++];
                        len --;
                        group_size++;
                }
                /* Align a short group properly. */
                v <<= 6 * (4 - group_size);
                /* Unpack the group we just collected. */
                switch (group_size) {
                case 4: d[2] = v & 0xff;
                        /* FALLTHROUGH */
                case 3: d[1] = (v >> 8) & 0xff;
                        /* FALLTHROUGH */
                case 2: d[0] = (v >> 16) & 0xff;
                        break;
                case 1: /* this is invalid! */
                        break;
                }
                d += group_size * 3 / 4;
        }

        *out_len = d - out;
        return (out);
}

/*
 * This is a little tricky because the C99 standard wcstombs()
 * function returns the number of bytes that were converted,
 * not the number that should be converted.  As a result,
 * we can never accurately size the output buffer (without
 * doing a tedious output size calculation in advance).
 * This approach (try a conversion, then try again if it fails)
 * will almost always succeed on the first try, and is thus
 * much faster, at the cost of sometimes requiring multiple
 * passes while we expand the buffer.
 */
static char *
wide_to_narrow(const wchar_t *wval)
{
        int converted_length;
        /* Guess an output buffer size and try the conversion. */
        int alloc_length = wcslen(wval) * 3;
        char *mbs_val = (char *)malloc(alloc_length + 1);
        if (mbs_val == NULL)
                return (NULL);
        converted_length = wcstombs(mbs_val, wval, alloc_length);

        /* If we exhausted the buffer, resize and try again. */
        while (converted_length >= alloc_length) {
                free(mbs_val);
                alloc_length *= 2;
                mbs_val = (char *)malloc(alloc_length + 1);
                if (mbs_val == NULL)
                        return (NULL);
                converted_length = wcstombs(mbs_val, wval, alloc_length);
        }

        /* Ensure a trailing null and return the final string. */
        mbs_val[alloc_length] = '\0';
        return (mbs_val);
}

static char *
url_decode(const char *in)
{
        char *out, *d;
        const char *s;

        out = (char *)malloc(strlen(in) + 1);
        if (out == NULL)
                return (NULL);
        for (s = in, d = out; *s != '\0'; ) {
                if (*s == '%') {
                        /* Try to convert % escape */
                        int digit1 = tohex(s[1]);
                        int digit2 = tohex(s[2]);
                        if (digit1 >= 0 && digit2 >= 0) {
                                /* Looks good, consume three chars */
                                s += 3;
                                /* Convert output */
                                *d++ = ((digit1 << 4) | digit2);
                                continue;
                        }
                        /* Else fall through and treat '%' as normal char */
                }
                *d++ = *s++;
        }
        *d = '\0';
        return (out);
}

static int
tohex(int c)
{
        if (c >= '0' && c <= '9')
                return (c - '0');
        else if (c >= 'A' && c <= 'F')
                return (c - 'A' + 10);
        else if (c >= 'a' && c <= 'f')
                return (c - 'a' + 10);
        else
                return (-1);
}