Spelling correction, thanks to Joerg Sonnenberger.

[FreeBSD/FreeBSD.git] / lib / libarchive / archive_write_disk.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
 *    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("$FreeBSD$");

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#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
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_SYS_UTIME_H
#include <sys/utime.h>
#endif

#ifdef HAVE_EXT2FS_EXT2_FS_H
#include <ext2fs/ext2_fs.h>     /* for Linux file flags */
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_GRP_H
#include <grp.h>
#endif
#ifdef HAVE_LINUX_FS_H
#include <linux/fs.h>   /* for Linux file flags */
#endif
#ifdef HAVE_LINUX_EXT2_FS_H
#include <linux/ext2_fs.h>      /* for Linux file flags */
#endif
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#include <stdio.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
#ifdef HAVE_UTIME_H
#include <utime.h>
#endif

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

#ifndef O_BINARY
#define O_BINARY 0
#endif

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;
};

/*
 * We use a bitmask to track which operations remain to be done for
 * this file.  In particular, this helps us avoid unnecessary
 * operations when it's possible to take care of one step as a
 * side-effect of another.  For example, mkdir() can specify the mode
 * for the newly-created object but symlink() cannot.  This means we
 * can skip chmod() if mkdir() succeeded, but we must explicitly
 * chmod() if we're trying to create a directory that already exists
 * (mkdir() failed) or if we're restoring a symlink.  Similarly, we
 * need to verify UID/GID before trying to restore SUID/SGID bits;
 * that verification can occur explicitly through a stat() call or
 * implicitly because of a successful chown() call.
 */
#define TODO_MODE_FORCE         0x40000000
#define TODO_MODE_BASE          0x20000000
#define TODO_SUID               0x10000000
#define TODO_SUID_CHECK         0x08000000
#define TODO_SGID               0x04000000
#define TODO_SGID_CHECK         0x02000000
#define TODO_MODE               (TODO_MODE_BASE|TODO_SUID|TODO_SGID)
#define TODO_TIMES              ARCHIVE_EXTRACT_TIME
#define TODO_OWNER              ARCHIVE_EXTRACT_OWNER
#define TODO_FFLAGS             ARCHIVE_EXTRACT_FFLAGS
#define TODO_ACLS               ARCHIVE_EXTRACT_ACL
#define TODO_XATTR              ARCHIVE_EXTRACT_XATTR

struct archive_write_disk {
        struct archive  archive;

        mode_t                   user_umask;
        struct fixup_entry      *fixup_list;
        struct fixup_entry      *current_fixup;
        uid_t                    user_uid;
        dev_t                    skip_file_dev;
        ino_t                    skip_file_ino;

        gid_t (*lookup_gid)(void *private, const char *gname, gid_t gid);
        void  (*cleanup_gid)(void *private);
        void                    *lookup_gid_data;
        uid_t (*lookup_uid)(void *private, const char *gname, gid_t gid);
        void  (*cleanup_uid)(void *private);
        void                    *lookup_uid_data;

        /*
         * Full path of last file to satisfy symlink checks.
         */
        struct archive_string   path_safe;

        /*
         * 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;

        /* Information about the object being restored right now. */
        struct archive_entry    *entry; /* Entry being extracted. */
        char                    *name; /* Name of entry, possibly edited. */
        struct archive_string    _name_data; /* backing store for 'name' */
        /* Tasks remaining for this object. */
        int                      todo;
        /* Tasks deferred until end-of-archive. */
        int                      deferred;
        /* Options requested by the client. */
        int                      flags;
        /* Handle for the file we're restoring. */
        int                      fd;
        /* Current offset for writing data to the file. */
        off_t                    offset;
        /* Maximum size of file. */
        off_t                    filesize;
        /* Dir we were in before this restore; only for deep paths. */
        int                      restore_pwd;
        /* Mode we should use for this entry; affected by _PERM and umask. */
        mode_t                   mode;
        /* UID/GID to use in restoring this entry. */
        uid_t                    uid;
        gid_t                    gid;
};

/*
 * Default mode for dirs created automatically (will be modified by umask).
 * Note that POSIX specifies 0777 for implicity-created dirs, "modified
 * by the process' file creation mask."
 */
#define DEFAULT_DIR_MODE 0777
/*
 * Dir modes are restored in two steps:  During the extraction, the permissions
 * in the archive are modified to match the following limits.  During
 * the post-extract fixup pass, the permissions from the archive are
 * applied.
 */
#define MINIMUM_DIR_MODE 0700
#define MAXIMUM_DIR_MODE 0775

static int      check_symlinks(struct archive_write_disk *);
static int      create_filesystem_object(struct archive_write_disk *);
static struct fixup_entry *current_fixup(struct archive_write_disk *, const char *pathname);
#ifdef HAVE_FCHDIR
static void     edit_deep_directories(struct archive_write_disk *ad);
#endif
static int      cleanup_pathname(struct archive_write_disk *);
static int      create_dir(struct archive_write_disk *, char *);
static int      create_parent_dir(struct archive_write_disk *, char *);
static int      older(struct stat *, struct archive_entry *);
static int      restore_entry(struct archive_write_disk *);
#ifdef HAVE_POSIX_ACL
static int      set_acl(struct archive_write_disk *, int fd, struct archive_entry *,
                    acl_type_t, int archive_entry_acl_type, const char *tn);
#endif
static int      set_acls(struct archive_write_disk *);
static int      set_xattrs(struct archive_write_disk *);
static int      set_fflags(struct archive_write_disk *);
static int      set_fflags_platform(struct archive_write_disk *, int fd,
                    const char *name, mode_t mode,
                    unsigned long fflags_set, unsigned long fflags_clear);
static int      set_ownership(struct archive_write_disk *);
static int      set_mode(struct archive_write_disk *, int mode);
static int      set_time(struct archive_write_disk *);
static struct fixup_entry *sort_dir_list(struct fixup_entry *p);
static gid_t    trivial_lookup_gid(void *, const char *, gid_t);
static uid_t    trivial_lookup_uid(void *, const char *, uid_t);


static struct archive_vtable *archive_write_disk_vtable(void);

static int      _archive_write_close(struct archive *);
static int      _archive_write_finish(struct archive *);
static int      _archive_write_header(struct archive *, struct archive_entry *);
static int      _archive_write_finish_entry(struct archive *);
static ssize_t  _archive_write_data(struct archive *, const void *, size_t);
static ssize_t  _archive_write_data_block(struct archive *, const void *, size_t, off_t);

static struct archive_vtable *
archive_write_disk_vtable(void)
{
        static struct archive_vtable av;
        static int inited = 0;

        if (!inited) {
                av.archive_write_close = _archive_write_close;
                av.archive_write_finish = _archive_write_finish;
                av.archive_write_header = _archive_write_header;
                av.archive_write_finish_entry = _archive_write_finish_entry;
                av.archive_write_data = _archive_write_data;
                av.archive_write_data_block = _archive_write_data_block;
        }
        return (&av);
}


int
archive_write_disk_set_options(struct archive *_a, int flags)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;

        a->flags = flags;
        return (ARCHIVE_OK);
}


/*
 * 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.
 *
 */
static int
_archive_write_header(struct archive *_a, struct archive_entry *entry)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        struct fixup_entry *fe;
        int ret, r;

        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_HEADER | ARCHIVE_STATE_DATA,
            "archive_write_disk_header");
        archive_clear_error(&a->archive);
        if (a->archive.state & ARCHIVE_STATE_DATA) {
                r = _archive_write_finish_entry(&a->archive);
                if (r != ARCHIVE_OK)
                        return (r);
        }

        /* Set up for this particular entry. */
        a->pst = NULL;
        a->current_fixup = NULL;
        a->deferred = 0;
        if (a->entry) {
                archive_entry_free(a->entry);
                a->entry = NULL;
        }
        a->entry = archive_entry_clone(entry);
        a->fd = -1;
        a->offset = 0;
        a->uid = a->user_uid;
        a->mode = archive_entry_mode(a->entry);
        a->filesize = archive_entry_size(a->entry);
        archive_strcpy(&(a->_name_data), archive_entry_pathname(a->entry));
        a->name = a->_name_data.s;
        archive_clear_error(&a->archive);

        /*
         * Clean up the requested path.  This is necessary for correct
         * dir restores; the dir restore logic otherwise gets messed
         * up by nonsense like "dir/.".
         */
        ret = cleanup_pathname(a);
        if (ret != ARCHIVE_OK)
                return (ret);

        /*
         * Set the umask to zero so we get predictable mode settings.
         * This gets done on every call to _write_header in case the
         * user edits their umask during the extraction for some
         * reason. This will be reset before we return.  Note that we
         * don't need to do this in _finish_entry, as the chmod(), etc,
         * system calls don't obey umask.
         */
        a->user_umask = umask(0);
        /* From here on, early exit requires "goto done" to clean up. */

        /* Figure out what we need to do for this entry. */
        a->todo = TODO_MODE_BASE;
        if (a->flags & ARCHIVE_EXTRACT_PERM) {
                a->todo |= TODO_MODE_FORCE; /* Be pushy about permissions. */
                /*
                 * SGID requires an extra "check" step because we
                 * cannot easily predict the GID that the system will
                 * assign.  (Different systems assign GIDs to files
                 * based on a variety of criteria, including process
                 * credentials and the gid of the enclosing
                 * directory.)  We can only restore the SGID bit if
                 * the file has the right GID, and we only know the
                 * GID if we either set it (see set_ownership) or if
                 * we've actually called stat() on the file after it
                 * was restored.  Since there are several places at
                 * which we might verify the GID, we need a TODO bit
                 * to keep track.
                 */
                if (a->mode & S_ISGID)
                        a->todo |= TODO_SGID | TODO_SGID_CHECK;
                /*
                 * Verifying the SUID is simpler, but can still be
                 * done in multiple ways, hence the separate "check" bit.
                 */
                if (a->mode & S_ISUID)
                        a->todo |= TODO_SUID | TODO_SUID_CHECK;
        } else {
                /*
                 * User didn't request full permissions, so don't
                 * restore SUID, SGID bits and obey umask.
                 */
                a->mode &= ~S_ISUID;
                a->mode &= ~S_ISGID;
                a->mode &= ~S_ISVTX;
                a->mode &= ~a->user_umask;
        }
        if (a->flags & ARCHIVE_EXTRACT_OWNER)
                a->todo |= TODO_OWNER;
        if (a->flags & ARCHIVE_EXTRACT_TIME)
                a->todo |= TODO_TIMES;
        if (a->flags & ARCHIVE_EXTRACT_ACL)
                a->todo |= TODO_ACLS;
        if (a->flags & ARCHIVE_EXTRACT_FFLAGS)
                a->todo |= TODO_FFLAGS;
        if (a->flags & ARCHIVE_EXTRACT_SECURE_SYMLINKS) {
                ret = check_symlinks(a);
                if (ret != ARCHIVE_OK)
                        goto done;
        }
#ifdef HAVE_FCHDIR
        /* If path exceeds PATH_MAX, shorten the path. */
        edit_deep_directories(a);
#endif

        ret = restore_entry(a);

#ifdef HAVE_FCHDIR
        /* If we changed directory above, restore it here. */
        if (a->restore_pwd >= 0) {
                fchdir(a->restore_pwd);
                close(a->restore_pwd);
                a->restore_pwd = -1;
        }
#endif

        /*
         * Fixup uses the unedited pathname from archive_entry_pathname(),
         * because it is relative to the base dir and the edited path
         * might be relative to some intermediate dir as a result of the
         * deep restore logic.
         */
        if (a->deferred & TODO_MODE) {
                fe = current_fixup(a, archive_entry_pathname(entry));
                fe->fixup |= TODO_MODE_BASE;
                fe->mode = a->mode;
        }

        if (a->deferred & TODO_TIMES) {
                fe = current_fixup(a, archive_entry_pathname(entry));
                fe->fixup |= TODO_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);
        }

        if (a->deferred & TODO_FFLAGS) {
                fe = current_fixup(a, archive_entry_pathname(entry));
                fe->fixup |= TODO_FFLAGS;
                /* TODO: Complete this.. defer fflags from below. */
        }

        /* We've created the object and are ready to pour data into it. */
        if (ret == ARCHIVE_OK)
                a->archive.state = ARCHIVE_STATE_DATA;
        /*
         * If it's not open, tell our client not to try writing.
         * In particular, dirs, links, etc, don't get written to.
         */
        if (a->fd < 0) {
                archive_entry_set_size(entry, 0);
                a->filesize = 0;
        }
done:
        /* Restore the user's umask before returning. */
        umask(a->user_umask);

        return (ret);
}

int
archive_write_disk_set_skip_file(struct archive *_a, dev_t d, ino_t i)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_ANY, "archive_write_disk_set_skip_file");
        a->skip_file_dev = d;
        a->skip_file_ino = i;
        return (ARCHIVE_OK);
}

static ssize_t
_archive_write_data_block(struct archive *_a,
    const void *buff, size_t size, off_t offset)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        ssize_t bytes_written = 0;
        int r = ARCHIVE_OK;

        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_DATA, "archive_write_disk_block");
        if (a->fd < 0) {
                archive_set_error(&a->archive, 0, "File not open");
                return (ARCHIVE_WARN);
        }
        archive_clear_error(&a->archive);

        /* Seek if necessary to the specified offset. */
        if (offset != a->offset) {
                if (lseek(a->fd, offset, SEEK_SET) < 0) {
                        archive_set_error(&a->archive, errno, "Seek failed");
                        return (ARCHIVE_WARN);
                }
                a->offset = offset;
        }

        /* Write the data. */
        while (size > 0 && a->offset < a->filesize) {
                if ((off_t)(a->offset + size) > a->filesize) {
                        size = (size_t)(a->filesize - a->offset);
                        archive_set_error(&a->archive, errno,
                            "Write request too large");
                        r = ARCHIVE_WARN;
                }
                bytes_written = write(a->fd, buff, size);
                if (bytes_written < 0) {
                        archive_set_error(&a->archive, errno, "Write failed");
                        return (ARCHIVE_WARN);
                }
                size -= bytes_written;
                a->offset += bytes_written;
        }
        return (r);
}

static ssize_t
_archive_write_data(struct archive *_a, const void *buff, size_t size)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        off_t offset;
        int r;

        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_DATA, "archive_write_data");
        if (a->fd < 0)
                return (ARCHIVE_OK);

        offset = a->offset;
        r = _archive_write_data_block(_a, buff, size, a->offset);
        if (r < ARCHIVE_OK)
                return (r);
        return (a->offset - offset);
}

static int
_archive_write_finish_entry(struct archive *_a)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        int ret = ARCHIVE_OK;

        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_HEADER | ARCHIVE_STATE_DATA,
            "archive_write_finish_entry");
        if (a->archive.state & ARCHIVE_STATE_HEADER)
                return (ARCHIVE_OK);
        archive_clear_error(&a->archive);

        /* Restore metadata. */

        /*
         * Look up the "real" UID only if we're going to need it.  We
         * need this for TODO_SGID because chown() requires both.
         */
        if (a->todo & (TODO_OWNER | TODO_SUID | TODO_SGID)) {
                a->uid = a->lookup_uid(a->lookup_uid_data,
                    archive_entry_uname(a->entry),
                    archive_entry_uid(a->entry));
        }
        /* Look up the "real" GID only if we're going to need it. */
        if (a->todo & (TODO_OWNER | TODO_SGID | TODO_SUID)) {
                a->gid = a->lookup_gid(a->lookup_gid_data,
                    archive_entry_gname(a->entry),
                    archive_entry_gid(a->entry));
         }
        /*
         * If restoring ownership, do it before trying to restore suid/sgid
         * bits.  If we set the owner, we know what it is and can skip
         * a stat() call to examine the ownership of the file on disk.
         */
        if (a->todo & TODO_OWNER)
                ret = set_ownership(a);
        if (a->todo & TODO_MODE) {
                int r2 = set_mode(a, a->mode);
                if (r2 < ret) ret = r2;
        }
        if (a->todo & TODO_TIMES) {
                int r2 = set_time(a);
                if (r2 < ret) ret = r2;
        }
        if (a->todo & TODO_ACLS) {
                int r2 = set_acls(a);
                if (r2 < ret) ret = r2;
        }
        if (a->todo & TODO_XATTR) {
                int r2 = set_xattrs(a);
                if (r2 < ret) ret = r2;
        }
        if (a->todo & TODO_FFLAGS) {
                int r2 = set_fflags(a);
                if (r2 < ret) ret = r2;
        }

        /* If there's an fd, we can close it now. */
        if (a->fd >= 0) {
                close(a->fd);
                a->fd = -1;
        }
        /* If there's an entry, we can release it now. */
        if (a->entry) {
                archive_entry_free(a->entry);
                a->entry = NULL;
        }
        a->archive.state = ARCHIVE_STATE_HEADER;
        return (ret);
}

int
archive_write_disk_set_group_lookup(struct archive *_a,
    void *private_data,
    gid_t (*lookup_gid)(void *private, const char *gname, gid_t gid),
    void (*cleanup_gid)(void *private))
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_ANY, "archive_write_disk_set_group_lookup");

        a->lookup_gid = lookup_gid;
        a->cleanup_gid = cleanup_gid;
        a->lookup_gid_data = private_data;
        return (ARCHIVE_OK);
}

int
archive_write_disk_set_user_lookup(struct archive *_a,
    void *private_data,
    uid_t (*lookup_uid)(void *private, const char *uname, uid_t uid),
    void (*cleanup_uid)(void *private))
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_ANY, "archive_write_disk_set_user_lookup");

        a->lookup_uid = lookup_uid;
        a->cleanup_uid = cleanup_uid;
        a->lookup_uid_data = private_data;
        return (ARCHIVE_OK);
}


/*
 * Create a new archive_write_disk object and initialize it with global state.
 */
struct archive *
archive_write_disk_new(void)
{
        struct archive_write_disk *a;

        a = (struct archive_write_disk *)malloc(sizeof(*a));
        if (a == NULL)
                return (NULL);
        memset(a, 0, sizeof(*a));
        a->archive.magic = ARCHIVE_WRITE_DISK_MAGIC;
        /* We're ready to write a header immediately. */
        a->archive.state = ARCHIVE_STATE_HEADER;
        a->archive.vtable = archive_write_disk_vtable();
        a->lookup_uid = trivial_lookup_uid;
        a->lookup_gid = trivial_lookup_gid;
#ifdef HAVE_GETEUID
        a->user_uid = geteuid();
#endif /* HAVE_GETEUID */
        if (archive_string_ensure(&a->path_safe, 512) == NULL) {
                free(a);
                return (NULL);
        }
        return (&a->archive);
}


/*
 * If pathname is longer than PATH_MAX, chdir to a suitable
 * intermediate dir and edit the path down to a shorter suffix.  Note
 * that this routine never returns an error; if the chdir() attempt
 * fails for any reason, we just go ahead with the long pathname.  The
 * object creation is likely to fail, but any error will get handled
 * at that time.
 */
#ifdef HAVE_FCHDIR
static void
edit_deep_directories(struct archive_write_disk *a)
{
        int ret;
        char *tail = a->name;

        a->restore_pwd = -1;

        /* If path is short, avoid the open() below. */
        if (strlen(tail) <= PATH_MAX)
                return;

        /* Try to record our starting dir. */
        a->restore_pwd = open(".", O_RDONLY | O_BINARY);
        if (a->restore_pwd < 0)
                return;

        /* As long as the path is too long... */
        while (strlen(tail) > PATH_MAX) {
                /* Locate a dir prefix shorter than PATH_MAX. */
                tail += PATH_MAX - 8;
                while (tail > a->name && *tail != '/')
                        tail--;
                /* Exit if we find a too-long path component. */
                if (tail <= a->name)
                        return;
                /* Create the intermediate dir and chdir to it. */
                *tail = '\0'; /* Terminate dir portion */
                ret = create_dir(a, a->name);
                if (ret == ARCHIVE_OK && chdir(a->name) != 0)
                        ret = ARCHIVE_WARN;
                *tail = '/'; /* Restore the / we removed. */
                if (ret != ARCHIVE_OK)
                        return;
                tail++;
                /* The chdir() succeeded; we've now shortened the path. */
                a->name = tail;
        }
        return;
}
#endif

/*
 * The main restore function.
 */
static int
restore_entry(struct archive_write_disk *a)
{
        int ret = ARCHIVE_OK, en;

        if (a->flags & ARCHIVE_EXTRACT_UNLINK && !S_ISDIR(a->mode)) {
                /*
                 * TODO: Fix this.  Apparently, there are platforms
                 * that still allow root to hose the entire filesystem
                 * by unlinking a dir.  The S_ISDIR() test above
                 * prevents us from using unlink() here if the new
                 * object is a dir, but that doesn't mean the old
                 * object isn't a dir.
                 */
                if (unlink(a->name) == 0) {
                        /* We removed it, we're done. */
                } else if (errno == ENOENT) {
                        /* File didn't exist, that's just as good. */
                } else if (rmdir(a->name) == 0) {
                        /* It was a dir, but now it's gone. */
                } else {
                        /* We tried, but couldn't get rid of it. */
                        archive_set_error(&a->archive, errno,
                            "Could not unlink");
                        return(ARCHIVE_WARN);
                }
        }

        /* Try creating it first; if this fails, we'll try to recover. */
        en = create_filesystem_object(a);

        if ((en == ENOTDIR || en == ENOENT)
            && !(a->flags & ARCHIVE_EXTRACT_NO_AUTODIR)) {
                /* If the parent dir doesn't exist, try creating it. */
                create_parent_dir(a, a->name);
                /* Now try to create the object again. */
                en = create_filesystem_object(a);
        }

        if ((en == EISDIR || en == EEXIST)
            && (a->flags & ARCHIVE_EXTRACT_NO_OVERWRITE)) {
                /* If we're not overwriting, we're done. */
                archive_set_error(&a->archive, en, "Already exists");
                return (ARCHIVE_WARN);
        }

        /*
         * Some platforms return EISDIR if you call
         * open(O_WRONLY | O_EXCL | O_CREAT) on a directory, some
         * return EEXIST.  POSIX is ambiguous, requiring EISDIR
         * for open(O_WRONLY) on a dir and EEXIST for open(O_EXCL | O_CREAT)
         * on an existing item.
         */
        if (en == EISDIR) {
                /* A dir is in the way of a non-dir, rmdir it. */
                if (rmdir(a->name) != 0) {
                        archive_set_error(&a->archive, errno,
                            "Can't remove already-existing dir");
                        return (ARCHIVE_WARN);
                }
                /* Try again. */
                en = create_filesystem_object(a);
        } else if (en == EEXIST) {
                /*
                 * We know something is in the way, but we don't know what;
                 * we need to find out before we go any further.
                 */
                if (lstat(a->name, &a->st) != 0) {
                        archive_set_error(&a->archive, errno,
                            "Can't stat existing object");
                        return (ARCHIVE_WARN);
                }

                /* TODO: if it's a symlink... */

                if (a->flags & ARCHIVE_EXTRACT_NO_OVERWRITE_NEWER) {
                        if (!older(&(a->st), a->entry)) {
                                archive_set_error(&a->archive, 0,
                                    "File on disk is not older; skipping.");
                                return (ARCHIVE_FAILED);
                        }
                }

                /* If it's our archive, we're done. */
                if (a->skip_file_dev > 0 &&
                    a->skip_file_ino > 0 &&
                    a->st.st_dev == a->skip_file_dev &&
                    a->st.st_ino == a->skip_file_ino) {
                        archive_set_error(&a->archive, 0, "Refusing to overwrite archive");
                        return (ARCHIVE_FAILED);
                }

                if (!S_ISDIR(a->st.st_mode)) {
                        /* A non-dir is in the way, unlink it. */
                        if (unlink(a->name) != 0) {
                                archive_set_error(&a->archive, errno,
                                    "Can't unlink already-existing object");
                                return (ARCHIVE_WARN);
                        }
                        /* Try again. */
                        en = create_filesystem_object(a);
                } else if (!S_ISDIR(a->mode)) {
                        /* A dir is in the way of a non-dir, rmdir it. */
                        if (rmdir(a->name) != 0) {
                                archive_set_error(&a->archive, errno,
                                    "Can't remove already-existing dir");
                                return (ARCHIVE_WARN);
                        }
                        /* Try again. */
                        en = create_filesystem_object(a);
                } else {
                        /*
                         * There's a dir in the way of a dir.  Don't
                         * waste time with rmdir()/mkdir(), just fix
                         * up the permissions on the existing dir.
                         * Note that we don't change perms on existing
                         * dirs unless _EXTRACT_PERM is specified.
                         */
                        if ((a->mode != a->st.st_mode)
                            && (a->todo & TODO_MODE_FORCE))
                                a->deferred |= (a->todo & TODO_MODE);
                        /* Ownership doesn't need deferred fixup. */
                        en = 0; /* Forget the EEXIST. */
                }
        }

        if (en) {
                /* Everything failed; give up here. */
                archive_set_error(&a->archive, en, "Can't create '%s'", a->name);
                return (ARCHIVE_WARN);
        }

        a->pst = NULL; /* Cached stat data no longer valid. */
        return (ret);
}

/*
 * Returns 0 if creation succeeds, or else returns errno value from
 * the failed system call.   Note:  This function should only ever perform
 * a single system call.
 */
int
create_filesystem_object(struct archive_write_disk *a)
{
        /* Create the entry. */
        const char *linkname;
        mode_t final_mode, mode;
        int r;

        /* We identify hard/symlinks according to the link names. */
        /* Since link(2) and symlink(2) don't handle modes, we're done here. */
        linkname = archive_entry_hardlink(a->entry);
        if (linkname != NULL) {
                r = link(linkname, a->name) ? errno : 0;
                /*
                 * New cpio and pax formats allow hardlink entries
                 * to carry data, so we may have to open the file
                 * for hardlink entries.
                 */
                if (r == 0 && a->filesize > 0) {
                        a->fd = open(a->name, O_WRONLY | O_TRUNC | O_BINARY);
                        if (a->fd < 0)
                                r = errno;
                }
                return (r);
        }
        linkname = archive_entry_symlink(a->entry);
        if (linkname != NULL)
                return symlink(linkname, a->name) ? errno : 0;

        /*
         * The remaining system calls all set permissions, so let's
         * try to take advantage of that to avoid an extra chmod()
         * call.  (Recall that umask is set to zero right now!)
         */

        /* Mode we want for the final restored object (w/o file type bits). */
        final_mode = a->mode & 07777;
        /*
         * The mode that will actually be restored in this step.  Note
         * that SUID, SGID, etc, require additional work to ensure
         * security, so we never restore them at this point.
         */
        mode = final_mode & 0777;

        switch (a->mode & AE_IFMT) {
        default:
                /* POSIX requires that we fall through here. */
                /* FALLTHROUGH */
        case AE_IFREG:
                a->fd = open(a->name,
                    O_WRONLY | O_CREAT | O_EXCL | O_BINARY, mode);
                r = (a->fd < 0);
                break;
        case AE_IFCHR:
#ifdef HAVE_MKNOD
                /* Note: we use AE_IFCHR for the case label, and
                 * S_IFCHR for the mknod() call.  This is correct.  */
                r = mknod(a->name, mode | S_IFCHR,
                    archive_entry_rdev(a->entry));
#else
                /* TODO: Find a better way to warn about our inability
                 * to restore a char device node. */
                return (EINVAL);
#endif /* HAVE_MKNOD */
                break;
        case AE_IFBLK:
#ifdef HAVE_MKNOD
                r = mknod(a->name, mode | S_IFBLK,
                    archive_entry_rdev(a->entry));
#else
                /* TODO: Find a better way to warn about our inability
                 * to restore a block device node. */
                return (EINVAL);
#endif /* HAVE_MKNOD */
                break;
        case AE_IFDIR:
                mode = (mode | MINIMUM_DIR_MODE) & MAXIMUM_DIR_MODE;
                r = mkdir(a->name, mode);
                if (r == 0) {
                        /* Defer setting dir times. */
                        a->deferred |= (a->todo & TODO_TIMES);
                        a->todo &= ~TODO_TIMES;
                        /* Never use an immediate chmod(). */
                        if (mode != final_mode)
                                a->deferred |= (a->todo & TODO_MODE);
                        a->todo &= ~TODO_MODE;
                }
                break;
        case AE_IFIFO:
#ifdef HAVE_MKFIFO
                r = mkfifo(a->name, mode);
#else
                /* TODO: Find a better way to warn about our inability
                 * to restore a fifo. */
                return (EINVAL);
#endif /* HAVE_MKFIFO */
                break;
        }

        /* All the system calls above set errno on failure. */
        if (r)
                return (errno);

        /* If we managed to set the final mode, we've avoided a chmod(). */
        if (mode == final_mode)
                a->todo &= ~TODO_MODE;
        return (0);
}

/*
 * 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 with minimum 0700 permissions 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
 */
static int
_archive_write_close(struct archive *_a)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        struct fixup_entry *next, *p;
        int ret;

        __archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
            ARCHIVE_STATE_HEADER | ARCHIVE_STATE_DATA,
            "archive_write_disk_close");
        ret = _archive_write_finish_entry(&a->archive);

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

        while (p != NULL) {
                a->pst = NULL; /* Mark stat cache as out-of-date. */
                if (p->fixup & TODO_TIMES) {
#ifdef HAVE_UTIMES
                        /* {f,l,}utimes() are preferred, when available. */
                        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;
#ifdef HAVE_LUTIMES
                        lutimes(p->name, times);
#else
                        utimes(p->name, times);
#endif
#else
                        /* utime() is more portable, but less precise. */
                        struct utimbuf times;
                        times.modtime = p->mtime;
                        times.actime = p->atime;

                        utime(p->name, &times);
#endif
                }
                if (p->fixup & TODO_MODE_BASE)
                        chmod(p->name, p->mode);

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

                next = p->next;
                free(p->name);
                free(p);
                p = next;
        }
        a->fixup_list = NULL;
        return (ret);
}

static int
_archive_write_finish(struct archive *_a)
{
        struct archive_write_disk *a = (struct archive_write_disk *)_a;
        int ret;
        ret = _archive_write_close(&a->archive);
        if (a->cleanup_gid != NULL && a->lookup_gid_data != NULL)
                (a->cleanup_gid)(a->lookup_gid_data);
        if (a->cleanup_uid != NULL && a->lookup_uid_data != NULL)
                (a->cleanup_uid)(a->lookup_uid_data);
        archive_string_free(&a->_name_data);
        archive_string_free(&a->archive.error_string);
        archive_string_free(&a->path_safe);
        free(a);
        return (ret);
}

/*
 * 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_write_disk *a, const char *pathname)
{
        struct fixup_entry *fe;

        fe = (struct fixup_entry *)malloc(sizeof(struct fixup_entry));
        if (fe == NULL)
                return (NULL);
        fe->next = a->fixup_list;
        a->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_write_disk *a, const char *pathname)
{
        if (a->current_fixup == NULL)
                a->current_fixup = new_fixup(a, pathname);
        return (a->current_fixup);
}

/* TODO: Make this work. */
/*
 * TODO: The deep-directory support bypasses this; disable deep directory
 * support if we're doing symlink checks.
 */
/*
 * TODO: Someday, integrate this with the deep dir support; they both
 * scan the path and both can be optimized by comparing against other
 * recent paths.
 */
static int
check_symlinks(struct archive_write_disk *a)
{
        char *pn, *p;
        char c;
        int r;
        struct stat st;

        /*
         * Guard against symlink tricks.  Reject any archive entry whose
         * destination would be altered by a symlink.
         */
        /* Whatever we checked last time doesn't need to be re-checked. */
        pn = a->name;
        p = a->path_safe.s;
        while ((*pn != '\0') && (*p == *pn))
                ++p, ++pn;
        c = pn[0];
        /* Keep going until we've checked the entire name. */
        while (pn[0] != '\0' && (pn[0] != '/' || pn[1] != '\0')) {
                /* Skip the next path element. */
                while (*pn != '\0' && *pn != '/')
                        ++pn;
                c = pn[0];
                pn[0] = '\0';
                /* Check that we haven't hit a symlink. */
                r = lstat(a->name, &st);
                if (r != 0) {
                        /* We've hit a dir that doesn't exist; stop now. */
                        if (errno == ENOENT)
                                break;
                } else if (S_ISLNK(st.st_mode)) {
                        if (c == '\0') {
                                /*
                                 * Last element is symlink; remove it
                                 * so we can overwrite it with the
                                 * item being extracted.
                                 */
                                if (unlink(a->name)) {
                                        archive_set_error(&a->archive, errno,
                                            "Could not remove symlink %s",
                                            a->name);
                                        pn[0] = c;
                                        return (ARCHIVE_WARN);
                                }
                                /*
                                 * Even if we did remove it, a warning
                                 * is in order.  The warning is silly,
                                 * though, if we're just replacing one
                                 * symlink with another symlink.
                                 */
                                if (!S_ISLNK(a->mode)) {
                                        archive_set_error(&a->archive, 0,
                                            "Removing symlink %s",
                                            a->name);
                                }
                                /* Symlink gone.  No more problem! */
                                pn[0] = c;
                                return (0);
                        } else if (a->flags & ARCHIVE_EXTRACT_UNLINK) {
                                /* User asked us to remove problems. */
                                if (unlink(a->name) != 0) {
                                        archive_set_error(&a->archive, 0,
                                            "Cannot remove intervening symlink %s",
                                            a->name);
                                        pn[0] = c;
                                        return (ARCHIVE_WARN);
                                }
                        } else {
                                archive_set_error(&a->archive, 0,
                                    "Cannot extract through symlink %s",
                                    a->name);
                                pn[0] = c;
                                return (ARCHIVE_WARN);
                        }
                }
        }
        pn[0] = c;
        /* We've checked and/or cleaned the whole path, so remember it. */
        archive_strcpy(&a->path_safe, a->name);
        return (ARCHIVE_OK);
}

/*
 * Canonicalize the pathname.  In particular, this strips duplicate
 * '/' characters, '.' elements, and trailing '/'.  It also raises an
 * error for an empty path, a trailing '..' or (if _SECURE_NODOTDOT is
 * set) any '..' in the path.
 */
static int
cleanup_pathname(struct archive_write_disk *a)
{
        char *dest, *src;
        char separator = '\0';
        int lastdotdot = 0; /* True if last elt copied was '..' */

        dest = src = a->name;
        if (*src == '\0') {
                archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                    "Invalid empty pathname");
                return (ARCHIVE_WARN);
        }

        /* Skip leading '/'. */
        if (*src == '/')
                separator = *src++;

        /* Scan the pathname one element at a time. */
        for (;;) {
                /* src points to first char after '/' */
                if (src[0] == '\0') {
                        break;
                } else if (src[0] == '/') {
                        /* Found '//', ignore second one. */
                        src++;
                        continue;
                } else if (src[0] == '.') {
                        if (src[1] == '\0') {
                                /* Ignore trailing '.' */
                                break;
                        } else if (src[1] == '/') {
                                /* Skip './'. */
                                src += 2;
                                continue;
                        } else if (src[1] == '.') {
                                if (src[2] == '/' || src[2] == '\0') {
                                        /* Conditionally warn about '..' */
                                        if (a->flags & ARCHIVE_EXTRACT_SECURE_NODOTDOT) {
                                                archive_set_error(&a->archive,
                                                    ARCHIVE_ERRNO_MISC,
                                                    "Path contains '..'");
                                                return (ARCHIVE_WARN);
                                        }
                                        lastdotdot = 1;
                                } else
                                        lastdotdot = 0;
                                /*
                                 * Note: Under no circumstances do we
                                 * remove '..' elements.  In
                                 * particular, restoring
                                 * '/foo/../bar/' should create the
                                 * 'foo' dir as a side-effect.
                                 */
                        } else
                                lastdotdot = 0;
                } else
                        lastdotdot = 0;

                /* Copy current element, including leading '/'. */
                if (separator)
                        *dest++ = '/';
                while (*src != '\0' && *src != '/') {
                        *dest++ = *src++;
                }

                if (*src == '\0')
                        break;

                /* Skip '/' separator. */
                separator = *src++;
        }
        /*
         * We've just copied zero or more path elements, not including the
         * final '/'.
         */
        if (lastdotdot) {
                /* Trailing '..' is always wrong. */
                archive_set_error(&a->archive,
                    ARCHIVE_ERRNO_MISC,
                    "Path contains trailing '..'");
                return (ARCHIVE_WARN);
        }
        if (dest == a->name) {
                /*
                 * Nothing got copied.  The path must have been something
                 * like '.' or '/' or './' or '/././././/./'.
                 */
                if (separator)
                        *dest++ = '/';
                else
                        *dest++ = '.';
        }
        /* Terminate the result. */
        *dest = '\0';
        return (ARCHIVE_OK);
}

/*
 * Create the parent directory of the specified path, assuming path
 * is already in mutable storage.
 */
static int
create_parent_dir(struct archive_write_disk *a, char *path)
{
        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(a, path);
        *slash = '/';
        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.
 * Assumes path is in mutable storage; path is unchanged on exit.
 */
static int
create_dir(struct archive_write_disk *a, char *path)
{
        struct stat st;
        struct fixup_entry *le;
        char *slash, *base;
        mode_t mode_final, mode;
        int r;

        r = ARCHIVE_OK;

        /* Check for special names and just skip them. */
        slash = 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(a, path);
                        *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 a->st cache.
         */
        if (stat(path, &st) == 0) {
                if (S_ISDIR(st.st_mode))
                        return (ARCHIVE_OK);
                if ((a->flags & ARCHIVE_EXTRACT_NO_OVERWRITE)) {
                        archive_set_error(&a->archive, EEXIST,
                            "Can't create directory '%s'", path);
                        return (ARCHIVE_WARN);
                }
                if (unlink(path) != 0) {
                        archive_set_error(&a->archive, 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->archive, errno, "Can't test directory '%s'", path);
                return (ARCHIVE_WARN);
        } else if (slash != NULL) {
                *slash = '\0';
                r = create_dir(a, path);
                *slash = '/';
                if (r != ARCHIVE_OK)
                        return (r);
        }

        /*
         * Mode we want for the final restored directory.  Per POSIX,
         * implicitly-created dirs must be created obeying the umask.
         * There's no mention whether this is different for privileged
         * restores (which the rest of this code handles by pretending
         * umask=0).  I've chosen here to always obey the user's umask for
         * implicit dirs, even if _EXTRACT_PERM was specified.
         */
        mode_final = DEFAULT_DIR_MODE & ~a->user_umask;
        /* Mode we want on disk during the restore process. */
        mode = mode_final;
        mode |= MINIMUM_DIR_MODE;
        mode &= MAXIMUM_DIR_MODE;
        if (mkdir(path, mode) == 0) {
                if (mode != mode_final) {
                        le = new_fixup(a, path);
                        le->fixup |=TODO_MODE_BASE;
                        le->mode = mode_final;
                }
                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->archive, errno, "Failed to create dir '%s'", path);
        return (ARCHIVE_WARN);
}

/*
 * Note: Although we can skip setting the user id if the desired user
 * id matches the current user, we cannot skip setting the group, as
 * many systems set the gid bit based on the containing directory.  So
 * we have to perform a chown syscall if we want to restore the SGID
 * bit.  (The alternative is to stat() and then possibly chown(); it's
 * more efficient to skip the stat() and just always chown().)  Note
 * that a successful chown() here clears the TODO_SGID_CHECK bit, which
 * allows set_mode to skip the stat() check for the GID.
 */
static int
set_ownership(struct archive_write_disk *a)
{
        /* If we know we can't change it, don't bother trying. */
        if (a->user_uid != 0  &&  a->user_uid != a->uid) {
                archive_set_error(&a->archive, errno,
                    "Can't set UID=%d", a->uid);
                return (ARCHIVE_WARN);
        }

#ifdef HAVE_FCHOWN
        /* If we have an fd, we can avoid a race. */
        if (a->fd >= 0 && fchown(a->fd, a->uid, a->gid) == 0) {
                /* We've set owner and know uid/gid are correct. */
                a->todo &= ~(TODO_OWNER | TODO_SGID_CHECK | TODO_SUID_CHECK);
                return (ARCHIVE_OK);
        }
#endif

        /* We prefer lchown() but will use chown() if that's all we have. */
        /* Of course, if we have neither, this will always fail. */
#ifdef HAVE_LCHOWN
        if (lchown(a->name, a->uid, a->gid) == 0) {
                /* We've set owner and know uid/gid are correct. */
                a->todo &= ~(TODO_OWNER | TODO_SGID_CHECK | TODO_SUID_CHECK);
                return (ARCHIVE_OK);
        }
#elif HAVE_CHOWN
        if (!S_ISLNK(a->mode) && chown(a->name, a->uid, a->gid) == 0) {
                /* We've set owner and know uid/gid are correct. */
                a->todo &= ~(TODO_OWNER | TODO_SGID_CHECK | TODO_SUID_CHECK);
                return (ARCHIVE_OK);
        }
#endif

        archive_set_error(&a->archive, errno,
            "Can't set user=%d/group=%d for %s", a->uid, a->gid,
            a->name);
        return (ARCHIVE_WARN);
}

#ifdef HAVE_UTIMES
/*
 * The utimes()-family functions provide high resolution and
 * a way to set time on an fd or a symlink.  We prefer them
 * when they're available.
 */
static int
set_time(struct archive_write_disk *a)
{
        struct timeval times[2];

        times[1].tv_sec = archive_entry_mtime(a->entry);
        times[1].tv_usec = archive_entry_mtime_nsec(a->entry) / 1000;

        times[0].tv_sec = archive_entry_atime(a->entry);
        times[0].tv_usec = archive_entry_atime_nsec(a->entry) / 1000;

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

#ifdef HAVE_LUTIMES
        if (lutimes(a->name, times) != 0)
#else
        if (!S_ISLNK(a->mode) && utimes(a->name, times) != 0)
#endif
        {
                archive_set_error(&a->archive, errno, "Can't update time for %s",
                    a->name);
                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);
}
#elif defined(HAVE_UTIME)
/*
 * utime() is an older, more standard interface that we'll use
 * if utimes() isn't available.
 */
static int
set_time(struct archive_write_disk *a)
{
        struct utimbuf times;

        times.modtime = archive_entry_mtime(a->entry);
        times.actime = archive_entry_atime(a->entry);
        if (!S_ISLNK(a->mode) && utime(a->name, &times) != 0) {
                archive_set_error(&a->archive, errno,
                    "Can't update time for %s", a->name);
                return (ARCHIVE_WARN);
        }
        return (ARCHIVE_OK);
}
#else
/* This platform doesn't give us a way to restore the time. */
static int
set_time(struct archive_write_disk *a)
{
        (void)a; /* UNUSED */
        archive_set_error(&a->archive, errno,
            "Can't update time for %s", a->name);
        return (ARCHIVE_WARN);
}
#endif


static int
set_mode(struct archive_write_disk *a, int mode)
{
        int r = ARCHIVE_OK;
        mode &= 07777; /* Strip off file type bits. */

        if (a->todo & TODO_SGID_CHECK) {
                /*
                 * If we don't know the GID is right, we must stat()
                 * to verify it.  We can't just check the GID of this
                 * process, since systems sometimes set GID from
                 * the enclosing dir or based on ACLs.
                 */
                if (a->pst != NULL) {
                        /* Already have stat() data available. */
#ifdef HAVE_FSTAT
                } else if (fd >= 0 && fstat(fd, &a->st) == 0) {
                        a->pst = &a->st;
#endif
                } else if (stat(a->name, &a->st) == 0) {
                        a->pst = &a->st;
                } else {
                        archive_set_error(&a->archive, errno,
                            "Couldn't stat file");
                        return (ARCHIVE_WARN);
                }
                if (a->pst->st_gid != a->gid) {
                        mode &= ~ S_ISGID;
                        if (a->flags & ARCHIVE_EXTRACT_OWNER) {
                                /*
                                 * This is only an error if you
                                 * requested owner restore.  If you
                                 * didn't, we'll try to restore
                                 * sgid/suid, but won't consider it a
                                 * problem if we can't.
                                 */
                                archive_set_error(&a->archive, -1,
                                    "Can't restore SGID bit");
                                r = ARCHIVE_WARN;
                        }
                }
                /* While we're here, double-check the UID. */
                if (a->pst->st_uid != a->uid
                    && (a->todo & TODO_SUID)) {
                        mode &= ~ S_ISUID;
                        if (a->flags & ARCHIVE_EXTRACT_OWNER) {
                                archive_set_error(&a->archive, -1,
                                    "Can't restore SUID bit");
                                r = ARCHIVE_WARN;
                        }
                }
                a->todo &= ~TODO_SGID_CHECK;
                a->todo &= ~TODO_SUID_CHECK;
        } else if (a->todo & TODO_SUID_CHECK) {
                /*
                 * If we don't know the UID is right, we can just check
                 * the user, since all systems set the file UID from
                 * the process UID.
                 */
                if (a->user_uid != a->uid) {
                        mode &= ~ S_ISUID;
                        if (a->flags & ARCHIVE_EXTRACT_OWNER) {
                                archive_set_error(&a->archive, -1,
                                    "Can't make file SUID");
                                r = ARCHIVE_WARN;
                        }
                }
                a->todo &= ~TODO_SUID_CHECK;
        }

        if (S_ISLNK(a->mode)) {
#ifdef HAVE_LCHMOD
                /*
                 * If this is a symlink, use lchmod().  If the
                 * platform doesn't support lchmod(), just skip it.  A
                 * platform that doesn't provide a way to set
                 * permissions on symlinks probably ignores
                 * permissions on symlinks, so a failure here has no
                 * impact.
                 */
                if (lchmod(a->name, mode) != 0) {
                        archive_set_error(&a->archive, errno,
                            "Can't set permissions to 0%o", (int)mode);
                        r = ARCHIVE_WARN;
                }
#endif
        } else if (!S_ISDIR(a->mode)) {
                /*
                 * If it's not a symlink and not a dir, then use
                 * fchmod() or chmod(), depending on whether we have
                 * an fd.  Dirs get their perms set during the
                 * post-extract fixup, which is handled elsewhere.
                 */
#ifdef HAVE_FCHMOD
                if (a->fd >= 0) {
                        if (fchmod(a->fd, mode) != 0) {
                                archive_set_error(&a->archive, errno,
                                    "Can't set permissions to 0%o", (int)mode);
                                r = ARCHIVE_WARN;
                        }
                } else
#endif
                        /* If this platform lacks fchmod(), then
                         * we'll just use chmod(). */
                        if (chmod(a->name, mode) != 0) {
                                archive_set_error(&a->archive, errno,
                                    "Can't set permissions to 0%o", (int)mode);
                                r = ARCHIVE_WARN;
                        }
        }
        return (r);
}

static int
set_fflags(struct archive_write_disk *a)
{
        struct fixup_entry *le;
        unsigned long   set, clear;
        int             r;
        int             critical_flags;
        mode_t          mode = archive_entry_mode(a->entry);

        /*
         * 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 (a->todo & TODO_FFLAGS) {
                archive_entry_fflags(a->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, a->name);
                        le->fixup |= TODO_FFLAGS;
                        le->fflags_set = set;
                        /* Store the mode if it's not already there. */
                        if ((le->fixup & TODO_MODE) == 0)
                                le->mode = mode;
                } else {
                        r = set_fflags_platform(a, a->fd,
                            a->name, 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_platform(struct archive_write_disk *a, int fd, const char *name,
    mode_t mode, unsigned long set, unsigned long clear)
{
        (void)mode; /* UNUSED */
        if (set == 0  && clear == 0)
                return (ARCHIVE_OK);

        /*
         * 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 (fd >= 0 && fstat(fd, &a->st) == 0)
                a->pst = &a->st;
        else if (lstat(name, &a->st) == 0)
                a->pst = &a->st;
        else {
                archive_set_error(&a->archive, errno,
                    "Couldn't stat file");
                return (ARCHIVE_WARN);
        }

        a->st.st_flags &= ~clear;
        a->st.st_flags |= set;
#ifdef HAVE_FCHFLAGS
        /* If platform has fchflags() and we were given an fd, use it. */
        if (fd >= 0 && fchflags(fd, a->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, a->st.st_flags) == 0)
                return (ARCHIVE_OK);
#elif defined(HAVE_CHFLAGS)
        if (S_ISLNK(a->st.st_mode)) {
                archive_set_error(&a->archive, errno,
                    "Can't set file flags on symlink.");
                return (ARCHIVE_WARN);
        }
        if (chflags(name, a->st.st_flags) == 0)
                return (ARCHIVE_OK);
#endif
        archive_set_error(&a->archive, 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_platform(struct archive_write_disk *a, int fd, const char *name,
    mode_t mode, unsigned long set, unsigned long clear)
{
        int              ret;
        int              myfd = fd;
        unsigned long newflags, oldflags;
        unsigned long sf_mask = 0;

        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 | O_BINARY);
        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->archive, 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_platform(struct archive_write_disk *a, int fd, const char *name,
    mode_t mode, unsigned long set, unsigned long clear)
{
        (void)a; /* UNUSED */
        (void)fd; /* UNUSED */
        (void)name; /* UNUSED */
        (void)mode; /* UNUSED */
        (void)set; /* UNUSED */
        (void)clear; /* UNUSED */
        return (ARCHIVE_OK);
}

#endif /* __linux */

#ifndef HAVE_POSIX_ACL
/* Default empty function body to satisfy mainline code. */
static int
set_acls(struct archive_write_disk *a)
{
        (void)a; /* UNUSED */
        return (ARCHIVE_OK);
}

#else

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

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


static int
set_acl(struct archive_write_disk *a, int fd, struct archive_entry *entry,
    acl_type_t acl_type, int ae_requested_type, const char *tname)
{
        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 = a->lookup_uid(a->lookup_uid_data,
                            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 = a->lookup_gid(a->lookup_gid_data,
                            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->archive, errno, "Failed to set %s acl", tname);
                ret = ARCHIVE_WARN;
        }
        acl_free(acl);
        return (ret);
}
#endif

#if HAVE_LSETXATTR
/*
 * Restore extended attributes -  Linux implementation
 */
static int
set_xattrs(struct archive_write_disk *a)
{
        struct archive_entry *entry = a->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 (a->fd >= 0)
                                e = fsetxattr(a->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->archive, errno,
                                                    "Cannot restore extended "
                                                    "attributes on this file "
                                                    "system");
                                        }
                                } else
                                        archive_set_error(&a->archive, errno,
                                            "Failed to set extended attribute");
                                ret = ARCHIVE_WARN;
                        }
                } else {
                        archive_set_error(&a->archive, 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_write_disk *a)
{
        static int warning_done = 0;

        /* 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(a->entry) != 0 && !warning_done) {
                warning_done = 1;
                archive_set_error(&a->archive, 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


/*
 * Trivial implementations of gid/uid lookup functions.
 * These are normally overridden by the client, but these stub
 * versions ensure that we always have something that works.
 */
static gid_t
trivial_lookup_gid(void *private_data, const char *gname, gid_t gid)
{
        (void)private_data; /* UNUSED */
        (void)gname; /* UNUSED */
        return (gid);
}

static uid_t
trivial_lookup_uid(void *private_data, const char *uname, uid_t uid)
{
        (void)private_data; /* UNUSED */
        (void)uname; /* UNUSED */
        return (uid);
}

/*
 * Test if file on disk is older than entry.
 */
static int
older(struct stat *st, struct archive_entry *entry)
{
        /* First, test the seconds and return if we have a definite answer. */
        /* Definitely older. */
        if (st->st_mtime < archive_entry_mtime(entry))
                return (1);
        /* Definitely younger. */
        if (st->st_mtime > archive_entry_mtime(entry))
                return (0);
        /* If this platform supports fractional seconds, try those. */
#if HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC
        /* Definitely older. */
        if (st->st_mtimespec.tv_nsec < archive_entry_mtime_nsec(entry))
                return (1);
        /* Definitely younger. */
        if (st->st_mtimespec.tv_nsec > archive_entry_mtime_nsec(entry))
                return (0);
#elif HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
        /* Definitely older. */
        if (st->st_mtim.tv_nsec < archive_entry_mtime_nsec(entry))
                return (1);
        /* Definitely older. */
        if (st->st_mtim.tv_nsec > archive_entry_mtime_nsec(entry))
                return (0);
#else
        /* This system doesn't have high-res timestamps. */
#endif
        /* Same age, so not older. */
        return (0);
}