Upgrade to libarchive 2.0.25 which gives us a nice speed boost along with

[dragonfly/port-amd64.git] / contrib / libarchive-1.3.1 / libarchive / archive_read_extract.c

/*-
 * Copyright (c) 2003-2005 Tim Kientzle
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer
 *    in this position and unchanged.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "archive_platform.h"
__FBSDID("$FreeBSD: src/lib/libarchive/archive_read_extract.c,v 1.47 2006/09/05 05:59:45 kientzle Exp $");

#include <sys/types.h>
#ifdef HAVE_SYS_ACL_H
#include <sys/acl.h>
#endif
#ifdef HAVE_ATTR_XATTR_H
#include <attr/xattr.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#include <sys/stat.h>
#include <sys/time.h>

#ifdef HAVE_EXT2FS_EXT2_FS_H
#include <ext2fs/ext2_fs.h>     /* for Linux file flags */
#endif
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#ifdef HAVE_LINUX_EXT2_FS_H
#include <linux/ext2_fs.h>      /* for Linux file flags */
#endif
#include <limits.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

struct fixup_entry {
        struct fixup_entry      *next;
        mode_t                   mode;
        int64_t                  mtime;
        int64_t                  atime;
        unsigned long            mtime_nanos;
        unsigned long            atime_nanos;
        unsigned long            fflags_set;
        int                      fixup; /* bitmask of what needs fixing */
        char                    *name;
};

#define FIXUP_MODE      1
#define FIXUP_TIMES     2
#define FIXUP_FFLAGS    4

struct bucket {
        char    *name;
        int      hash;
        id_t     id;
};

struct extract {
        mode_t                   umask;
        mode_t                   default_dir_mode;
        struct archive_string    create_parent_dir;
        struct fixup_entry      *fixup_list;
        struct fixup_entry      *current_fixup;

        struct bucket ucache[127];
        struct bucket gcache[127];

        /*
         * Cached stat data from disk for the current entry.
         * If this is valid, pst points to st.  Otherwise,
         * pst is null.
         */
        struct stat              st;
        struct stat             *pst;
};

/* Default mode for dirs created automatically (will be modified by umask). */
#define DEFAULT_DIR_MODE 0777
/*
 * Mode to use for newly-created dirs during extraction; the correct
 * mode will be set at the end of the extraction.
 */
#define SECURE_DIR_MODE 0700

static int      archive_extract_cleanup(struct archive *);
static int      extract_block_device(struct archive *,
                    struct archive_entry *, int);
static int      extract_char_device(struct archive *,
                    struct archive_entry *, int);
static int      extract_device(struct archive *,
                    struct archive_entry *, int flags, mode_t mode);
static int      extract_dir(struct archive *, struct archive_entry *, int);
static int      extract_fifo(struct archive *, struct archive_entry *, int);
static int      extract_file(struct archive *, struct archive_entry *, int);
static int      extract_hard_link(struct archive *, struct archive_entry *, int);
static int      extract_symlink(struct archive *, struct archive_entry *, int);
static unsigned int     hash(const char *);
static gid_t    lookup_gid(struct archive *, const char *uname, gid_t);
static uid_t    lookup_uid(struct archive *, const char *uname, uid_t);
static int      create_dir(struct archive *, const char *, int flags);
static int      create_dir_mutable(struct archive *, char *, int flags);
static int      create_dir_recursive(struct archive *, char *, int flags);
static int      create_parent_dir(struct archive *, const char *, int flags);
static int      create_parent_dir_mutable(struct archive *, char *, int flags);
static int      restore_metadata(struct archive *, int fd,
                    struct archive_entry *, int flags);
#ifdef HAVE_POSIX_ACL
static int      set_acl(struct archive *, int fd, struct archive_entry *,
                    acl_type_t, int archive_entry_acl_type, const char *tn);
#endif
static int      set_acls(struct archive *, int fd, struct archive_entry *);
static int      set_xattrs(struct archive *, int fd, struct archive_entry *);
static int      set_fflags(struct archive *, int fd, const char *name, mode_t,
                    unsigned long fflags_set, unsigned long fflags_clear);
static int      set_ownership(struct archive *, int fd, struct archive_entry *,
                    int flags);
static int      set_perm(struct archive *, int fd, struct archive_entry *,
                    int mode, int flags);
static int      set_time(struct archive *, int fd, struct archive_entry *, int);
static struct fixup_entry *sort_dir_list(struct fixup_entry *p);


/*
 * Extract this entry to disk.
 *
 * TODO: Validate hardlinks.  According to the standards, we're
 * supposed to check each extracted hardlink and squawk if it refers
 * to a file that we didn't restore.  I'm not entirely convinced this
 * is a good idea, but more importantly: Is there any way to validate
 * hardlinks without keeping a complete list of filenames from the
 * entire archive?? Ugh.
 *
 */
int
archive_read_extract(struct archive *a, struct archive_entry *entry, int flags)
{
        mode_t mode;
        struct extract *extract;
        int ret;
        int restore_pwd;
        char *original_filename;

        if (a->extract == NULL) {
                a->extract = malloc(sizeof(*a->extract));
                if (a->extract == NULL) {
                        archive_set_error(a, ENOMEM, "Can't extract");
                        return (ARCHIVE_FATAL);
                }
                a->cleanup_archive_extract = archive_extract_cleanup;
                memset(a->extract, 0, sizeof(*a->extract));
        }
        extract = a->extract;
        umask(extract->umask = umask(0)); /* Read the current umask. */
        extract->default_dir_mode = DEFAULT_DIR_MODE & ~extract->umask;
        extract->pst = NULL;
        extract->current_fixup = NULL;
        restore_pwd = -1;
        original_filename = NULL;

        /* The following is not possible without fchdir.  <sigh> */
#ifdef HAVE_FCHDIR
        /*
         * If pathname is longer than PATH_MAX, record starting directory
         * and chdir to a suitable intermediate dir.
         */
        if (strlen(archive_entry_pathname(entry)) > PATH_MAX) {
                char *intdir, *tail;

                restore_pwd = open(".", O_RDONLY);
                if (restore_pwd < 0) {
                                archive_set_error(a, errno,
                                    "Unable to restore long pathname");
                                return (ARCHIVE_WARN);
                }

                /*
                 * Yes, the copy here is necessary because we edit
                 * the pathname in-place to create intermediate dirnames.
                 */
                original_filename = strdup(archive_entry_pathname(entry));

                /*
                 * "intdir" points to the initial dir section we're going
                 * to remove, "tail" points to the remainder of the path.
                 */
                intdir = tail = original_filename;
                while (strlen(tail) > PATH_MAX) {
                        intdir = tail;

                        /* Locate a dir prefix shorter than PATH_MAX. */
                        tail = intdir + PATH_MAX - 8;
                        while (tail > intdir && *tail != '/')
                                tail--;
                        if (tail <= intdir) {
                                archive_set_error(a, EPERM,
                                    "Path element too long");
                                ret = ARCHIVE_WARN;
                                goto cleanup;
                        }

                        /* Create intdir and chdir to it. */
                        *tail = '\0'; /* Terminate dir portion */
                        ret = create_dir(a, intdir, flags);
                        if (ret == ARCHIVE_OK && chdir(intdir) != 0) {
                                archive_set_error(a, errno, "Couldn't chdir");
                                ret = ARCHIVE_WARN;
                        }
                        *tail = '/'; /* Restore the / we removed. */
                        if (ret != ARCHIVE_OK)
                                goto cleanup;
                        tail++;
                }
                archive_entry_set_pathname(entry, tail);
        }
#endif

        if (stat(archive_entry_pathname(entry), &extract->st) == 0)
                extract->pst = &extract->st;

        if (extract->pst != NULL &&
            extract->pst->st_dev == a->skip_file_dev &&
            extract->pst->st_ino == a->skip_file_ino) {
                archive_set_error(a, 0, "Refusing to overwrite archive");
                ret = ARCHIVE_WARN;
        } else if (archive_entry_hardlink(entry) != NULL)
                ret = extract_hard_link(a, entry, flags);
        else {
                mode = archive_entry_mode(entry);
                switch (mode & S_IFMT) {
                default:
                        /* Fall through, as required by POSIX. */
                case S_IFREG:
                        ret = extract_file(a, entry, flags);
                        break;
                case S_IFLNK:   /* Symlink */
                        ret = extract_symlink(a, entry, flags);
                        break;
                case S_IFCHR:
                        ret = extract_char_device(a, entry, flags);
                        break;
                case S_IFBLK:
                        ret = extract_block_device(a, entry, flags);
                        break;
                case S_IFDIR:
                        ret = extract_dir(a, entry, flags);
                        break;
                case S_IFIFO:
                        ret = extract_fifo(a, entry, flags);
                        break;
                }
        }


cleanup:
#ifdef HAVE_FCHDIR
        /* If we changed directory above, restore it here. */
        if (restore_pwd >= 0 && original_filename != NULL) {
                fchdir(restore_pwd);
                close(restore_pwd);
                archive_entry_copy_pathname(entry, original_filename);
                free(original_filename);
        }
#endif

        return (ret);
}

/*
 * Cleanup function for archive_extract.  Mostly, this involves processing
 * the fixup list, which is used to address a number of problems:
 *   * Dir permissions might prevent us from restoring a file in that
 *     dir, so we restore the dir 0700 first, then correct the
 *     mode at the end.
 *   * Similarly, the act of restoring a file touches the directory
 *     and changes the timestamp on the dir, so we have to touch-up dir
 *     timestamps at the end as well.
 *   * Some file flags can interfere with the restore by, for example,
 *     preventing the creation of hardlinks to those files.
 *
 * Note that tar/cpio do not require that archives be in a particular
 * order; there is no way to know when the last file has been restored
 * within a directory, so there's no way to optimize the memory usage
 * here by fixing up the directory any earlier than the
 * end-of-archive.
 *
 * XXX TODO: Directory ACLs should be restored here, for the same
 * reason we set directory perms here. XXX
 *
 * Registering this function (rather than calling it explicitly by
 * name from archive_read_finish) reduces static link pollution, since
 * applications that don't use this API won't get this file linked in.
 */
static int
archive_extract_cleanup(struct archive *a)
{
        struct fixup_entry *next, *p;
        struct extract *extract;

        /* Sort dir list so directories are fixed up in depth-first order. */
        extract = a->extract;
        p = sort_dir_list(extract->fixup_list);

        while (p != NULL) {
                extract->pst = NULL; /* Mark stat cache as out-of-date. */
                if (p->fixup & FIXUP_TIMES) {
                        struct timeval times[2];
                        times[1].tv_sec = p->mtime;
                        times[1].tv_usec = p->mtime_nanos / 1000;
                        times[0].tv_sec = p->atime;
                        times[0].tv_usec = p->atime_nanos / 1000;
                        utimes(p->name, times);
                }
                if (p->fixup & FIXUP_MODE)
                        chmod(p->name, p->mode);

                if (p->fixup & FIXUP_FFLAGS)
                        set_fflags(a, -1, p->name, p->mode, p->fflags_set, 0);

                next = p->next;
                free(p->name);
                free(p);
                p = next;
        }
        extract->fixup_list = NULL;
        archive_string_free(&extract->create_parent_dir);
        free(a->extract);
        a->extract = NULL;
        return (ARCHIVE_OK);
}

/*
 * Simple O(n log n) merge sort to order the fixup list.  In
 * particular, we want to restore dir timestamps depth-first.
 */
static struct fixup_entry *
sort_dir_list(struct fixup_entry *p)
{
        struct fixup_entry *a, *b, *t;

        if (p == NULL)
                return (NULL);
        /* A one-item list is already sorted. */
        if (p->next == NULL)
                return (p);

        /* Step 1: split the list. */
        t = p;
        a = p->next->next;
        while (a != NULL) {
                /* Step a twice, t once. */
                a = a->next;
                if (a != NULL)
                        a = a->next;
                t = t->next;
        }
        /* Now, t is at the mid-point, so break the list here. */
        b = t->next;
        t->next = NULL;
        a = p;

        /* Step 2: Recursively sort the two sub-lists. */
        a = sort_dir_list(a);
        b = sort_dir_list(b);

        /* Step 3: Merge the returned lists. */
        /* Pick the first element for the merged list. */
        if (strcmp(a->name, b->name) > 0) {
                t = p = a;
                a = a->next;
        } else {
                t = p = b;
                b = b->next;
        }

        /* Always put the later element on the list first. */
        while (a != NULL && b != NULL) {
                if (strcmp(a->name, b->name) > 0) {
                        t->next = a;
                        a = a->next;
                } else {
                        t->next = b;
                        b = b->next;
                }
                t = t->next;
        }

        /* Only one list is non-empty, so just splice it on. */
        if (a != NULL)
                t->next = a;
        if (b != NULL)
                t->next = b;

        return (p);
}

/*
 * Returns a new, initialized fixup entry.
 *
 * TODO: Reduce the memory requirements for this list by using a tree
 * structure rather than a simple list of names.
 */
static struct fixup_entry *
new_fixup(struct archive *a, const char *pathname)
{
        struct extract *extract;
        struct fixup_entry *fe;

        extract = a->extract;
        fe = malloc(sizeof(struct fixup_entry));
        if (fe == NULL)
                return (NULL);
        fe->next = extract->fixup_list;
        extract->fixup_list = fe;
        fe->fixup = 0;
        fe->name = strdup(pathname);
        return (fe);
}

/*
 * Returns a fixup structure for the current entry.
 */
static struct fixup_entry *
current_fixup(struct archive *a, const char *pathname)
{
        struct extract *extract;

        extract = a->extract;
        if (extract->current_fixup == NULL)
                extract->current_fixup = new_fixup(a, pathname);
        return (extract->current_fixup);
}

static int
extract_file(struct archive *a, struct archive_entry *entry, int flags)
{
        struct extract *extract;
        const char *name;
        mode_t mode;
        int fd, r, r2;

        extract = a->extract;
        name = archive_entry_pathname(entry);
        mode = archive_entry_mode(entry) & 0777;
        r = ARCHIVE_OK;

        /*
         * If we're not supposed to overwrite pre-existing files,
         * use O_EXCL.  Otherwise, use O_TRUNC.
         */
        if (flags & (ARCHIVE_EXTRACT_UNLINK | ARCHIVE_EXTRACT_NO_OVERWRITE))
                fd = open(name, O_WRONLY | O_CREAT | O_EXCL, mode);
        else
                fd = open(name, O_WRONLY | O_CREAT | O_TRUNC, mode);

        /* Try removing a pre-existing file. */
        if (fd < 0 && !(flags & ARCHIVE_EXTRACT_NO_OVERWRITE)) {
                unlink(name);
                fd = open(name, O_WRONLY | O_CREAT | O_EXCL, mode);
        }

        /* Might be a non-existent parent dir; try fixing that. */
        if (fd < 0) {
                create_parent_dir(a, name, flags);
                fd = open(name, O_WRONLY | O_CREAT | O_EXCL, mode);
        }
        if (fd < 0) {
                archive_set_error(a, errno, "Can't open '%s'", name);
                return (ARCHIVE_WARN);
        }
        r = archive_read_data_into_fd(a, fd);
        extract->pst = NULL; /* Cached stat data no longer valid. */
        r2 = restore_metadata(a, fd, entry, flags);
        close(fd);
        return (err_combine(r, r2));
}

static int
extract_dir(struct archive *a, struct archive_entry *entry, int flags)
{
        struct extract *extract;
        struct fixup_entry *fe;
        char *path, *p;

        extract = a->extract;
        extract->pst = NULL; /* Invalidate cached stat data. */

        /* Copy path to mutable storage. */
        archive_strcpy(&(extract->create_parent_dir),
            archive_entry_pathname(entry));
        path = extract->create_parent_dir.s;

        if (*path == '\0') {
                archive_set_error(a, ARCHIVE_ERRNO_MISC,
                    "Invalid empty pathname");
                return (ARCHIVE_WARN);
        }

        /* Deal with any troublesome trailing path elements. */
        /* TODO: Someday, generalize this to remove '//' or '/./' from
         * the middle of paths.  But, it should not compress '..' from
         * the middle of paths.  It's a feature that restoring
         * "a/../b" creates both 'a' and 'b' directories. */
        for (;;) {
                /* Locate last element. */
                p = strrchr(path, '/');
                if (p != NULL)
                        p++;
                else
                        p = path;
                /* Trim trailing '/' unless that's the entire path. */
                if (p[0] == '\0' && p - 1 > path) {
                        p[-1] = '\0';
                        continue;
                }
                /* Trim trailing '.' unless that's the entire path. */
                if (p > path && p[0] == '.' && p[1] == '\0') {
                        p[0] = '\0';
                        continue;
                }
                /* Just exit on trailing '..'. */
                if (p[0] == '.' && p[1] == '.' && p[2] == '\0') {
                        archive_set_error(a, ARCHIVE_ERRNO_MISC,
                            "Can't restore directory '..'");
                        return (ARCHIVE_WARN);
                }
                break;
        }

        if (mkdir(path, SECURE_DIR_MODE) == 0)
                goto success;

        if (extract->pst == NULL && stat(path, &extract->st) == 0)
                extract->pst = &extract->st;

        if (extract->pst != NULL) {
                extract->pst = &extract->st;
                /* If dir already exists, don't reset permissions. */
                if (S_ISDIR(extract->pst->st_mode))
                        return (ARCHIVE_OK);
                /* It exists but isn't a dir. */
                if ((flags & ARCHIVE_EXTRACT_UNLINK))
                        unlink(path);
        } else {
                /* Doesn't already exist; try building the parent path. */
                if (create_parent_dir_mutable(a, path, flags) != ARCHIVE_OK)
                        return (ARCHIVE_WARN);
        }

        /* One final attempt to create the dir. */
        if (mkdir(path, SECURE_DIR_MODE) != 0) {
                archive_set_error(a, errno, "Can't create directory");
                return (ARCHIVE_WARN);
        }

success:
        /* Add this dir to the fixup list. */
        fe = current_fixup(a, path);
        fe->fixup |= FIXUP_MODE;
        fe->mode = archive_entry_mode(entry);
        if ((flags & ARCHIVE_EXTRACT_PERM) == 0)
                fe->mode &= ~extract->umask;
        if (flags & ARCHIVE_EXTRACT_TIME) {
                fe->fixup |= FIXUP_TIMES;
                fe->mtime = archive_entry_mtime(entry);
                fe->mtime_nanos = archive_entry_mtime_nsec(entry);
                fe->atime = archive_entry_atime(entry);
                fe->atime_nanos = archive_entry_atime_nsec(entry);
        }
        /* For now, set the mode to SECURE_DIR_MODE. */
        archive_entry_set_mode(entry, SECURE_DIR_MODE);
        return (restore_metadata(a, -1, entry, flags));
}


/*
 * Create the parent of the specified path.  Copy the provided
 * path into mutable storage first.
 */
static int
create_parent_dir(struct archive *a, const char *path, int flags)
{
        int r;

        /* Copy path to mutable storage. */
        archive_strcpy(&(a->extract->create_parent_dir), path);
        r = create_parent_dir_mutable(a, a->extract->create_parent_dir.s, flags);
        return (r);
}

/*
 * Like create_parent_dir, but creates the dir actually requested, not
 * the parent.
 */
static int
create_dir(struct archive *a, const char *path, int flags)
{
        int r;
        /* Copy path to mutable storage. */
        archive_strcpy(&(a->extract->create_parent_dir), path);
        r = create_dir_mutable(a, a->extract->create_parent_dir.s, flags);
        return (r);
}

/*
 * Create the parent directory of the specified path, assuming path
 * is already in mutable storage.
 */
static int
create_parent_dir_mutable(struct archive *a, char *path, int flags)
{
        char *slash;
        int r;

        /* Remove tail element to obtain parent name. */
        slash = strrchr(path, '/');
        if (slash == NULL)
                return (ARCHIVE_OK);
        *slash = '\0';
        r = create_dir_mutable(a, path, flags);
        *slash = '/';
        return (r);
}

/*
 * Create the specified dir, assuming path is already in
 * mutable storage.
 */
static int
create_dir_mutable(struct archive *a, char *path, int flags)
{
        mode_t old_umask;
        int r;

        old_umask = umask(~SECURE_DIR_MODE);
        r = create_dir_recursive(a, path, flags);
        umask(old_umask);
        return (r);
}

/*
 * Create the specified dir, recursing to create parents as necessary.
 *
 * Returns ARCHIVE_OK if the path exists when we're done here.
 * Otherwise, returns ARCHIVE_WARN.
 */
static int
create_dir_recursive(struct archive *a, char *path, int flags)
{
        struct stat st;
        struct extract *extract;
        struct fixup_entry *le;
        char *slash, *base;
        int r;

        extract = a->extract;
        r = ARCHIVE_OK;

        /* Check for special names and just skip them. */
        slash = strrchr(path, '/');
        base = strrchr(path, '/');
        if (slash == NULL)
                base = path;
        else
                base = slash + 1;

        if (base[0] == '\0' ||
            (base[0] == '.' && base[1] == '\0') ||
            (base[0] == '.' && base[1] == '.' && base[2] == '\0')) {
                /* Don't bother trying to create null path, '.', or '..'. */
                if (slash != NULL) {
                        *slash = '\0';
                        r = create_dir_recursive(a, path, flags);
                        *slash = '/';
                        return (r);
                }
                return (ARCHIVE_OK);
        }

        /*
         * Yes, this should be stat() and not lstat().  Using lstat()
         * here loses the ability to extract through symlinks.  Also note
         * that this should not use the extract->st cache.
         */
        if (stat(path, &st) == 0) {
                if (S_ISDIR(st.st_mode))
                        return (ARCHIVE_OK);
                if ((flags & ARCHIVE_EXTRACT_NO_OVERWRITE)) {
                        archive_set_error(a, EEXIST,
                            "Can't create directory '%s'", path);
                        return (ARCHIVE_WARN);
                }
                if (unlink(path) != 0) {
                        archive_set_error(a, errno,
                            "Can't create directory '%s': "
                            "Conflicting file cannot be removed");
                        return (ARCHIVE_WARN);
                }
        } else if (errno != ENOENT && errno != ENOTDIR) {
                /* Stat failed? */
                archive_set_error(a, errno, "Can't test directory '%s'", path);
                return (ARCHIVE_WARN);
        } else if (slash != NULL) {
                *slash = '\0';
                r = create_dir_recursive(a, path, flags);
                *slash = '/';
                if (r != ARCHIVE_OK)
                        return (r);
        }

        if (mkdir(path, SECURE_DIR_MODE) == 0) {
                le = new_fixup(a, path);
                le->fixup |= FIXUP_MODE;
                le->mode = extract->default_dir_mode;
                return (ARCHIVE_OK);
        }

        /*
         * Without the following check, a/b/../b/c/d fails at the
         * second visit to 'b', so 'd' can't be created.  Note that we
         * don't add it to the fixup list here, as it's already been
         * added.
         */
        if (stat(path, &st) == 0 && S_ISDIR(st.st_mode))
                return (ARCHIVE_OK);

        archive_set_error(a, errno, "Failed to create dir '%s'", path);
        return (ARCHIVE_WARN);
}

static int
extract_hard_link(struct archive *a, struct archive_entry *entry, int flags)
{
        struct extract *extract;
        int r;
        const char *pathname;
        const char *linkname;

        extract = a->extract;
        pathname = archive_entry_pathname(entry);
        linkname = archive_entry_hardlink(entry);

        /* Just remove any pre-existing file with this name. */
        if (!(flags & ARCHIVE_EXTRACT_NO_OVERWRITE))
                unlink(pathname);

        r = link(linkname, pathname);
        extract->pst = NULL; /* Invalidate cached stat data. */

        if (r != 0) {
                /* Might be a non-existent parent dir; try fixing that. */
                create_parent_dir(a, pathname, flags);
                r = link(linkname, pathname);
        }

        if (r != 0) {
                /* XXX Better error message here XXX */
                archive_set_error(a, errno,
                    "Can't restore hardlink to '%s'", linkname);
                return (ARCHIVE_WARN);
        }

        /* Set ownership, time, permission information. */
        r = restore_metadata(a, -1, entry, flags);
        return (r);
}

static int
extract_symlink(struct archive *a, struct archive_entry *entry, int flags)
{
        struct extract *extract;
        int r;
        const char *pathname;
        const char *linkname;

        extract = a->extract;
        pathname = archive_entry_pathname(entry);
        linkname = archive_entry_symlink(entry);

        /* Just remove any pre-existing file with this name. */
        if (!(flags & ARCHIVE_EXTRACT_NO_OVERWRITE))
                unlink(pathname);

        r = symlink(linkname, pathname);
        extract->pst = NULL; /* Invalidate cached stat data. */

        if (r != 0) {
                /* Might be a non-existent parent dir; try fixing that. */
                create_parent_dir(a, pathname, flags);
                r = symlink(linkname, pathname);
        }

        if (r != 0) {
                /* XXX Better error message here XXX */
                archive_set_error(a, errno,
                    "Can't restore symlink to '%s'", linkname);
                return (ARCHIVE_WARN);
        }

        r = restore_metadata(a, -1, entry, flags);
        return (r);
}

static int
extract_device(struct archive *a, struct archive_entry *entry,
    int flags, mode_t mode)
{
        struct extract *extract;
        int r;

        extract = a->extract;
        /* Just remove any pre-existing file with this name. */
        if (!(flags & ARCHIVE_EXTRACT_NO_OVERWRITE))
                unlink(archive_entry_pathname(entry));

        r = mknod(archive_entry_pathname(entry), mode,
            archive_entry_rdev(entry));
        extract->pst = NULL; /* Invalidate cached stat data. */

        /* Might be a non-existent parent dir; try fixing that. */
        if (r != 0 && errno == ENOENT) {
                create_parent_dir(a, archive_entry_pathname(entry), flags);
                r = mknod(archive_entry_pathname(entry), mode,
                    archive_entry_rdev(entry));
        }

        if (r != 0) {
                archive_set_error(a, errno, "Can't restore device node");
                return (ARCHIVE_WARN);
        }

        r = restore_metadata(a, -1, entry, flags);
        return (r);
}

static int
extract_char_device(struct archive *a, struct archive_entry *entry, int flags)
{
        mode_t mode;

        mode = (archive_entry_mode(entry) & ~S_IFMT) | S_IFCHR;
        return (extract_device(a, entry, flags, mode));
}

static int
extract_block_device(struct archive *a, struct archive_entry *entry, int flags)
{
        mode_t mode;

        mode = (archive_entry_mode(entry) & ~S_IFMT) | S_IFBLK;
        return (extract_device(a, entry, flags, mode));
}

static int
extract_fifo(struct archive *a, struct archive_entry *entry, int flags)
{
        struct extract *extract;
        int r;

        extract = a->extract;
        /* Just remove any pre-existing file with this name. */
        if (!(flags & ARCHIVE_EXTRACT_NO_OVERWRITE))
                unlink(archive_entry_pathname(entry));

        r = mkfifo(archive_entry_pathname(entry),
            archive_entry_mode(entry));
        extract->pst = NULL; /* Invalidate cached stat data. */

        /* Might be a non-existent parent dir; try fixing that. */
        if (r != 0 && errno == ENOENT) {
                create_parent_dir(a, archive_entry_pathname(entry), flags);
                r = mkfifo(archive_entry_pathname(entry),
                    archive_entry_mode(entry));
        }

        if (r != 0) {
                archive_set_error(a, errno, "Can't restore fifo");
                return (ARCHIVE_WARN);
        }

        r = restore_metadata(a, -1, entry, flags);
        return (r);
}

static int
restore_metadata(struct archive *a, int fd, struct archive_entry *entry, int flags)
{
        int r, r2;

        r = set_ownership(a, fd, entry, flags);
        r2 = set_time(a, fd, entry, flags);
        r = err_combine(r, r2);
        r2 = set_perm(a, fd, entry, archive_entry_mode(entry), flags);
        return (err_combine(r, r2));
}

static int
set_ownership(struct archive *a, int fd,
    struct archive_entry *entry, int flags)
{
        uid_t uid;
        gid_t gid;

        /* Not changed. */
        if ((flags & ARCHIVE_EXTRACT_OWNER) == 0)
                return (ARCHIVE_OK);

        uid = lookup_uid(a, archive_entry_uname(entry),
            archive_entry_uid(entry));
        gid = lookup_gid(a, archive_entry_gname(entry),
            archive_entry_gid(entry));

        /* If we know we can't change it, don't bother trying. */
        if (a->user_uid != 0  &&  a->user_uid != uid)
                return (ARCHIVE_OK);

#ifdef HAVE_FCHOWN
        if (fd >= 0 && fchown(fd, uid, gid) == 0)
                return (ARCHIVE_OK);
#endif

#ifdef HAVE_LCHOWN
        if (lchown(archive_entry_pathname(entry), uid, gid))
#else
        if (!S_ISLNK(archive_entry_mode(entry))
            && chown(archive_entry_pathname(entry), uid, gid) != 0)
#endif
        {
                archive_set_error(a, errno,
                    "Can't set user=%d/group=%d for %s", uid, gid,
                    archive_entry_pathname(entry));
                return (ARCHIVE_WARN);
        }
        return (ARCHIVE_OK);
}

static int
set_time(struct archive *a, int fd, struct archive_entry *entry, int flags)
{
        const struct stat *st;
        struct timeval times[2];

        (void)a; /* UNUSED */
        st = archive_entry_stat(entry);

        if ((flags & ARCHIVE_EXTRACT_TIME) == 0)
                return (ARCHIVE_OK);
        /* It's a waste of time to mess with dir timestamps here. */
        if (S_ISDIR(archive_entry_mode(entry)))
                return (ARCHIVE_OK);

        times[1].tv_sec = st->st_mtime;
        times[1].tv_usec = ARCHIVE_STAT_MTIME_NANOS(st) / 1000;

        times[0].tv_sec = st->st_atime;
        times[0].tv_usec = ARCHIVE_STAT_ATIME_NANOS(st) / 1000;

#ifdef HAVE_FUTIMES
        if (fd >= 0 && futimes(fd, times) == 0)
                return (ARCHIVE_OK);
#endif

#ifdef HAVE_LUTIMES
        if (lutimes(archive_entry_pathname(entry), times) != 0) {
#else
        if ((archive_entry_mode(entry) & S_IFMT) != S_IFLNK &&
            utimes(archive_entry_pathname(entry), times) != 0) {
#endif
                archive_set_error(a, errno, "Can't update time for %s",
                    archive_entry_pathname(entry));
                return (ARCHIVE_WARN);
        }

        /*
         * Note: POSIX does not provide a portable way to restore ctime.
         * (Apart from resetting the system clock, which is distasteful.)
         * So, any restoration of ctime will necessarily be OS-specific.
         */

        /* XXX TODO: Can FreeBSD restore ctime? XXX */

        return (ARCHIVE_OK);
}

static int
set_perm(struct archive *a, int fd, struct archive_entry *entry,
    int mode, int flags)
{
        struct extract *extract;
        struct fixup_entry *le;
        const char *name;
        unsigned long    set, clear;
        int              r;
        int              critical_flags;

        extract = a->extract;

        /* Obey umask unless ARCHIVE_EXTRACT_PERM. */
        if ((flags & ARCHIVE_EXTRACT_PERM) == 0)
                mode &= ~extract->umask; /* Enforce umask. */
        name = archive_entry_pathname(entry);

        if (mode & (S_ISUID | S_ISGID)) {
                if (extract->pst != NULL) {
                        /* Already have stat() data available. */
#ifdef HAVE_FSTAT
                } else if (fd >= 0 && fstat(fd, &extract->st) == 0) {
                        extract->pst = &extract->st;
#endif
                } else if (stat(name, &extract->st) == 0) {
                        extract->pst = &extract->st;
                } else {
                        archive_set_error(a, errno,
                            "Couldn't stat file");
                        return (ARCHIVE_WARN);
                }

                /*
                 * TODO: Use the uid/gid looked up in set_ownership
                 * above rather than the uid/gid stored in the entry.
                 */
                if (extract->pst->st_uid != archive_entry_uid(entry))
                        mode &= ~ S_ISUID;
                if (extract->pst->st_gid != archive_entry_gid(entry))
                        mode &= ~ S_ISGID;
        }

        /*
         * Ensure we change permissions on the object we extracted,
         * and not any incidental symlink that might have gotten in
         * the way.
         */
        if (!S_ISLNK(archive_entry_mode(entry))) {
#ifdef HAVE_FCHMOD
                if (fd >= 0) {
                        if (fchmod(fd, mode) != 0) {
                                archive_set_error(a, errno,
                                    "Can't set permissions");
                                return (ARCHIVE_WARN);
                        }
                } else
#endif
                if (chmod(name, mode) != 0) {
                        archive_set_error(a, errno, "Can't set permissions");
                        return (ARCHIVE_WARN);
                }
#ifdef HAVE_LCHMOD
        } else {
                /*
                 * If lchmod() isn't supported, it's no big deal.
                 * Permissions on symlinks are actually ignored on
                 * most platforms.
                 */
                if (lchmod(name, mode) != 0) {
                        archive_set_error(a, errno, "Can't set permissions");
                        return (ARCHIVE_WARN);
                }
#endif
        }

        if (flags & ARCHIVE_EXTRACT_ACL) {
                r = set_acls(a, fd, entry);
                if (r != ARCHIVE_OK)
                        return (r);
        }

        if (flags & ARCHIVE_EXTRACT_XATTR) {
                r = set_xattrs(a, fd, entry);
                if (r != ARCHIVE_OK)
                        return (r);
        }

        /*
         * Make 'critical_flags' hold all file flags that can't be
         * immediately restored.  For example, on BSD systems,
         * SF_IMMUTABLE prevents hardlinks from being created, so
         * should not be set until after any hardlinks are created.  To
         * preserve some semblance of portability, this uses #ifdef
         * extensively.  Ugly, but it works.
         *
         * Yes, Virginia, this does create a security race.  It's mitigated
         * somewhat by the practice of creating dirs 0700 until the extract
         * is done, but it would be nice if we could do more than that.
         * People restoring critical file systems should be wary of
         * other programs that might try to muck with files as they're
         * being restored.
         */
        /* Hopefully, the compiler will optimize this mess into a constant. */
        critical_flags = 0;
#ifdef SF_IMMUTABLE
        critical_flags |= SF_IMMUTABLE;
#endif
#ifdef UF_IMMUTABLE
        critical_flags |= UF_IMMUTABLE;
#endif
#ifdef SF_APPEND
        critical_flags |= SF_APPEND;
#endif
#ifdef UF_APPEND
        critical_flags |= UF_APPEND;
#endif
#ifdef EXT2_APPEND_FL
        critical_flags |= EXT2_APPEND_FL;
#endif
#ifdef EXT2_IMMUTABLE_FL
        critical_flags |= EXT2_IMMUTABLE_FL;
#endif

        if (flags & ARCHIVE_EXTRACT_FFLAGS) {
                archive_entry_fflags(entry, &set, &clear);

                /*
                 * The first test encourages the compiler to eliminate
                 * all of this if it's not necessary.
                 */
                if ((critical_flags != 0)  &&  (set & critical_flags)) {
                        le = current_fixup(a, archive_entry_pathname(entry));
                        le->fixup |= FIXUP_FFLAGS;
                        le->fflags_set = set;
                        /* Store the mode if it's not already there. */
                        if ((le->fixup & FIXUP_MODE) == 0)
                                le->mode = mode;
                } else {
                        r = set_fflags(a, fd, archive_entry_pathname(entry),
                            mode, set, clear);
                        if (r != ARCHIVE_OK)
                                return (r);
                }
        }
        return (ARCHIVE_OK);
}


#if ( defined(HAVE_LCHFLAGS) || defined(HAVE_CHFLAGS) || defined(HAVE_FCHFLAGS) ) && !defined(__linux)
static int
set_fflags(struct archive *a, int fd, const char *name, mode_t mode,
    unsigned long set, unsigned long clear)
{
        struct extract *extract;

        extract = a->extract;
        if (set == 0  && clear == 0)
                return (ARCHIVE_OK);

        (void)mode; /* UNUSED */
        /*
         * XXX Is the stat here really necessary?  Or can I just use
         * the 'set' flags directly?  In particular, I'm not sure
         * about the correct approach if we're overwriting an existing
         * file that already has flags on it. XXX
         */
        if (extract->pst != NULL) {
                /* Already have stat() data available. */
        } else if (fd >= 0 && fstat(fd, &extract->st) == 0)
                extract->pst = &extract->st;
        else if (stat(name, &extract->st) == 0)
                extract->pst = &extract->st;
        else {
                archive_set_error(a, errno,
                    "Couldn't stat file");
                return (ARCHIVE_WARN);
        }

        extract->st.st_flags &= ~clear;
        extract->st.st_flags |= set;
#ifdef HAVE_FCHFLAGS
        /* If platform has fchflags() and we were given an fd, use it. */
        if (fd >= 0 && fchflags(fd, extract->st.st_flags) == 0)
                return (ARCHIVE_OK);
#endif
        /*
         * If we can't use the fd to set the flags, we'll use the
         * pathname to set flags.  We prefer lchflags() but will use
         * chflags() if we must.
         */
#ifdef HAVE_LCHFLAGS
        if (lchflags(name, extract->st.st_flags) == 0)
                return (ARCHIVE_OK);
#elif defined(HAVE_CHFLAGS)
        if (chflags(name, extract->st.st_flags) == 0)
                return (ARCHIVE_OK);
#endif
        archive_set_error(a, errno,
            "Failed to set file flags");
        return (ARCHIVE_WARN);
}

#elif defined(__linux) && defined(EXT2_IOC_GETFLAGS) && defined(EXT2_IOC_SETFLAGS)

/*
 * Linux has flags too, but uses ioctl() to access them instead of
 * having a separate chflags() system call.
 */
static int
set_fflags(struct archive *a, int fd, const char *name, mode_t mode,
    unsigned long set, unsigned long clear)
{
        struct extract *extract;
        int              ret;
        int              myfd = fd;
        unsigned long newflags, oldflags;
        unsigned long sf_mask = 0;

        extract = a->extract;
        if (set == 0  && clear == 0)
                return (ARCHIVE_OK);
        /* Only regular files and dirs can have flags. */
        if (!S_ISREG(mode) && !S_ISDIR(mode))
                return (ARCHIVE_OK);

        /* If we weren't given an fd, open it ourselves. */
        if (myfd < 0)
                myfd = open(name, O_RDONLY|O_NONBLOCK);
        if (myfd < 0)
                return (ARCHIVE_OK);

        /*
         * Linux has no define for the flags that are only settable by
         * the root user.  This code may seem a little complex, but
         * there seem to be some Linux systems that lack these
         * defines. (?)  The code below degrades reasonably gracefully
         * if sf_mask is incomplete.
         */
#ifdef EXT2_IMMUTABLE_FL
        sf_mask |= EXT2_IMMUTABLE_FL;
#endif
#ifdef EXT2_APPEND_FL
        sf_mask |= EXT2_APPEND_FL;
#endif
        /*
         * XXX As above, this would be way simpler if we didn't have
         * to read the current flags from disk. XXX
         */
        ret = ARCHIVE_OK;
        /* Try setting the flags as given. */
        if (ioctl(myfd, EXT2_IOC_GETFLAGS, &oldflags) >= 0) {
                newflags = (oldflags & ~clear) | set;
                if (ioctl(myfd, EXT2_IOC_SETFLAGS, &newflags) >= 0)
                        goto cleanup;
                if (errno != EPERM)
                        goto fail;
        }
        /* If we couldn't set all the flags, try again with a subset. */
        if (ioctl(myfd, EXT2_IOC_GETFLAGS, &oldflags) >= 0) {
                newflags &= ~sf_mask;
                oldflags &= sf_mask;
                newflags |= oldflags;
                if (ioctl(myfd, EXT2_IOC_SETFLAGS, &newflags) >= 0)
                        goto cleanup;
        }
        /* We couldn't set the flags, so report the failure. */
fail:
        archive_set_error(a, errno,
            "Failed to set file flags");
        ret = ARCHIVE_WARN;
cleanup:
        if (fd < 0)
                close(myfd);
        return (ret);
}

#else /* Not HAVE_CHFLAGS && Not __linux */

/*
 * Of course, some systems have neither BSD chflags() nor Linux' flags
 * support through ioctl().
 */
static int
set_fflags(struct archive *a, int fd, const char *name, mode_t mode,
    unsigned long set, unsigned long clear)
{
        (void)a;
        (void)fd;
        (void)name;
        (void)mode;
        (void)set;
        (void)clear;
        return (ARCHIVE_OK);
}

#endif /* __linux */

#ifndef HAVE_POSIX_ACL
/* Default empty function body to satisfy mainline code. */
static int
set_acls(struct archive *a, int fd, struct archive_entry *entry)
{
        (void)a;
        (void)fd;
        (void)entry;

        return (ARCHIVE_OK);
}

#else

/*
 * XXX TODO: What about ACL types other than ACCESS and DEFAULT?
 */
static int
set_acls(struct archive *a, int fd, struct archive_entry *entry)
{
        int              ret;

        ret = set_acl(a, fd, entry, ACL_TYPE_ACCESS,
            ARCHIVE_ENTRY_ACL_TYPE_ACCESS, "access");
        if (ret != ARCHIVE_OK)
                return (ret);
        ret = set_acl(a, fd, entry, ACL_TYPE_DEFAULT,
            ARCHIVE_ENTRY_ACL_TYPE_DEFAULT, "default");
        return (ret);
}


static int
set_acl(struct archive *a, int fd, struct archive_entry *entry,
    acl_type_t acl_type, int ae_requested_type, const char *typename)
{
        acl_t            acl;
        acl_entry_t      acl_entry;
        acl_permset_t    acl_permset;
        int              ret;
        int              ae_type, ae_permset, ae_tag, ae_id;
        uid_t            ae_uid;
        gid_t            ae_gid;
        const char      *ae_name;
        int              entries;
        const char      *name;

        ret = ARCHIVE_OK;
        entries = archive_entry_acl_reset(entry, ae_requested_type);
        if (entries == 0)
                return (ARCHIVE_OK);
        acl = acl_init(entries);
        while (archive_entry_acl_next(entry, ae_requested_type, &ae_type,
                   &ae_permset, &ae_tag, &ae_id, &ae_name) == ARCHIVE_OK) {
                acl_create_entry(&acl, &acl_entry);

                switch (ae_tag) {
                case ARCHIVE_ENTRY_ACL_USER:
                        acl_set_tag_type(acl_entry, ACL_USER);
                        ae_uid = lookup_uid(a, ae_name, ae_id);
                        acl_set_qualifier(acl_entry, &ae_uid);
                        break;
                case ARCHIVE_ENTRY_ACL_GROUP:
                        acl_set_tag_type(acl_entry, ACL_GROUP);
                        ae_gid = lookup_gid(a, ae_name, ae_id);
                        acl_set_qualifier(acl_entry, &ae_gid);
                        break;
                case ARCHIVE_ENTRY_ACL_USER_OBJ:
                        acl_set_tag_type(acl_entry, ACL_USER_OBJ);
                        break;
                case ARCHIVE_ENTRY_ACL_GROUP_OBJ:
                        acl_set_tag_type(acl_entry, ACL_GROUP_OBJ);
                        break;
                case ARCHIVE_ENTRY_ACL_MASK:
                        acl_set_tag_type(acl_entry, ACL_MASK);
                        break;
                case ARCHIVE_ENTRY_ACL_OTHER:
                        acl_set_tag_type(acl_entry, ACL_OTHER);
                        break;
                default:
                        /* XXX */
                        break;
                }

                acl_get_permset(acl_entry, &acl_permset);
                acl_clear_perms(acl_permset);
                if (ae_permset & ARCHIVE_ENTRY_ACL_EXECUTE)
                        acl_add_perm(acl_permset, ACL_EXECUTE);
                if (ae_permset & ARCHIVE_ENTRY_ACL_WRITE)
                        acl_add_perm(acl_permset, ACL_WRITE);
                if (ae_permset & ARCHIVE_ENTRY_ACL_READ)
                        acl_add_perm(acl_permset, ACL_READ);
        }

        name = archive_entry_pathname(entry);

        /* Try restoring the ACL through 'fd' if we can. */
#if HAVE_ACL_SET_FD
        if (fd >= 0 && acl_type == ACL_TYPE_ACCESS && acl_set_fd(fd, acl) == 0)
                ret = ARCHIVE_OK;
        else
#else
#if HAVE_ACL_SET_FD_NP
        if (fd >= 0 && acl_set_fd_np(fd, acl, acl_type) == 0)
                ret = ARCHIVE_OK;
        else
#endif
#endif
        if (acl_set_file(name, acl_type, acl) != 0) {
                archive_set_error(a, errno, "Failed to set %s acl", typename);
                ret = ARCHIVE_WARN;
        }
        acl_free(acl);
        return (ret);
}
#endif

#if HAVE_LSETXATTR
/*
 * Restore extended attributes -  Linux implementation
 */
static int
set_xattrs(struct archive *a, int fd, struct archive_entry *entry)
{
        static int warning_done = 0;
        int ret = ARCHIVE_OK;
        int i = archive_entry_xattr_reset(entry);

        while (i--) {
                const char *name;
                const void *value;
                size_t size;
                archive_entry_xattr_next(entry, &name, &value, &size);
                if (name != NULL &&
                                strncmp(name, "xfsroot.", 8) != 0 &&
                                strncmp(name, "system.", 7) != 0) {
                        int e;
#if HAVE_FSETXATTR
                        if (fd >= 0)
                                e = fsetxattr(fd, name, value, size, 0);
                        else
#endif
                        {
                                e = lsetxattr(archive_entry_pathname(entry),
                                    name, value, size, 0);
                        }
                        if (e == -1) {
                                if (errno == ENOTSUP) {
                                        if (!warning_done) {
                                                warning_done = 1;
                                                archive_set_error(a, errno,
                                                    "Cannot restore extended "
                                                    "attributes on this file "
                                                    "system");
                                        }
                                } else
                                        archive_set_error(a, errno,
                                            "Failed to set extended attribute");
                                ret = ARCHIVE_WARN;
                        }
                } else {
                        archive_set_error(a, ARCHIVE_ERRNO_FILE_FORMAT,
                            "Invalid extended attribute encountered");
                        ret = ARCHIVE_WARN;
                }
        }
        return (ret);
}
#else
/*
 * Restore extended attributes - stub implementation for unsupported systems
 */
static int
set_xattrs(struct archive *a, int fd, struct archive_entry *entry)
{
        static int warning_done = 0;
        (void)a; /* UNUSED */
        (void)fd; /* UNUSED */

        /* If there aren't any extended attributes, then it's okay not
         * to extract them, otherwise, issue a single warning. */
        if (archive_entry_xattr_count(entry) != 0 && !warning_done) {
                warning_done = 1;
                archive_set_error(a, ARCHIVE_ERRNO_FILE_FORMAT,
                    "Cannot restore extended attributes on this system");
                return (ARCHIVE_WARN);
        }
        /* Warning was already emitted; suppress further warnings. */
        return (ARCHIVE_OK);
}
#endif

/*
 * The following routines do some basic caching of uname/gname
 * lookups.  All such lookups go through these routines, including ACL
 * conversions.  Even a small cache here provides an enormous speedup,
 * especially on systems using NIS, LDAP, or a similar networked
 * directory system.
 *
 * TODO: Provide an API for clients to override these routines.
 */
static gid_t
lookup_gid(struct archive *a, const char *gname, gid_t gid)
{
        struct group    *grent;
        struct extract *extract;
        int h;
        struct bucket *b;
        int cache_size;

        extract = a->extract;
        cache_size = sizeof(extract->gcache) / sizeof(extract->gcache[0]);

        /* If no gname, just use the gid provided. */
        if (gname == NULL || *gname == '\0')
                return (gid);

        /* Try to find gname in the cache. */
        h = hash(gname);
        b = &extract->gcache[h % cache_size ];
        if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
                return ((gid_t)b->id);

        /* Free the cache slot for a new entry. */
        if (b->name != NULL)
                free(b->name);
        b->name = strdup(gname);
        /* Note: If strdup fails, that's okay; we just won't cache. */
        b->hash = h;
        grent = getgrnam(gname);
        if (grent != NULL)
                gid = grent->gr_gid;
        b->id = gid;

        return (gid);
}

static uid_t
lookup_uid(struct archive *a, const char *uname, uid_t uid)
{
        struct passwd   *pwent;
        struct extract *extract;
        int h;
        struct bucket *b;
        int cache_size;

        extract = a->extract;
        cache_size = sizeof(extract->ucache) / sizeof(extract->ucache[0]);

        /* If no uname, just use the uid provided. */
        if (uname == NULL || *uname == '\0')
                return (uid);

        /* Try to find uname in the cache. */
        h = hash(uname);
        b = &extract->ucache[h % cache_size ];
        if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
                return ((uid_t)b->id);

        /* Free the cache slot for a new entry. */
        if (b->name != NULL)
                free(b->name);
        b->name = strdup(uname);
        /* Note: If strdup fails, that's okay; we just won't cache. */
        b->hash = h;
        pwent = getpwnam(uname);
        if (pwent != NULL)
                uid = pwent->pw_uid;
        b->id = uid;

        return (uid);
}

static unsigned int
hash(const char *p)
{
        /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
           as used by ELF for hashing function names. */
        unsigned g, h = 0;
        while (*p != '\0') {
                h = ( h << 4 ) + *p++;
                if (( g = h & 0xF0000000 )) {
                        h ^= g >> 24;
                        h &= 0x0FFFFFFF;
                }
        }
        return h;
}

void
archive_read_extract_set_progress_callback(struct archive *a,
    void (*progress_func)(void *), void *user_data)
{
        a->extract_progress = progress_func;
        a->extract_progress_user_data = user_data;
}