Initial commit to git.

10 files changed, 2430 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
new file mode 100644
index 0000000..f123526
--- /dev/null
+++ b/src/Makefile.am
@@ -0,0 +1,11 @@
+## Process this file with automake to produce Makefile.in
+
+bin_PROGRAMS = bindfs
+
+noinst_HEADERS = debug.h permchain.h userinfo.h misc.h
+bindfs_SOURCES = bindfs.c permchain.c userinfo.c misc.c
+
+AM_CFLAGS = $(fuse_CFLAGS)
+bindfs_LDADD = $(fuse_LIBS)
+
+man_MANS = bindfs.1
diff --git a/src/bindfs.1 b/src/bindfs.1
new file mode 100644
index 0000000..92444a2
--- /dev/null
+++ b/src/bindfs.1
@@ -0,0 +1,338 @@
+.TH BINDFS 1
+
+
+.SH NAME
+bindfs \(hy mount \-\-bind in user\-space
+
+
+.SH SYNOPSIS
+\fBbindfs\fP [\fIoptions\fP]\fI dir mountpoint
+
+
+.SH DESCRIPTION
+A FUSE filesystem for mirroring the contents of a directory to another
+directory. Additionally, one can change the permissions
+of files in the mirrored directory.
+
+
+.SH OPTIONS
+.TP
+.B \-h, \-\-help
+Displays a help message and exits.
+
+.TP
+.B \-V, \-\-version
+Displays version information and exits.
+
+.TP
+.B \-u, \-\-user, \-\-owner=\fIuser\fP, \-o owner=...
+Makes all files owned by the specified user.
+Also causes chown on the mounted filesystem to always fail.
+
+.TP
+.B \-g, \-\-group=\fIgroup\fP, \-o group=...
+Makes all files owned by the specified group.
+Also causes chgrp on the mounted filesystem to always fail.
+
+.TP
+.B \-p, \-\-perms=\fIpermissions\fP, \-o perms=...
+Takes a comma\- or colon\-separated list of chmod\-like permission
+specifications to be applied to the permission bits in order.
+See \fB\%PERMISSION \%SPECIFICATION\fP below for details.
+
+This only affects how the permission bits of existing files are altered
+when shown in the mounted directory. You can use \-\-create\-with\-perms to
+change the permissions that newly created files get in the source directory.
+
+Note that, as usual, the root user isn't bound by the permissions set here.
+You can get a truly read-only mount by using \fB-r\fP.
+
+.TP
+.B \-m, \-\-mirror=\fIusers\fP, \-o mirror=...
+Takes a comma\- or colon\-separated list of users who will see themselves as
+the owners of all files. Users who are not listed here will still be able
+to access the mount if the permissions otherwise allow them to.
+
+You can also give a group name prefixed with an '@' to mirror all members of
+a group. This will not change which group the files are shown to have.
+
+.TP
+.B \-M, \-\-mirror\-only=\fIusers\fP, \-o mirror\-only=...
+Like \fB\-\-mirror\fP but disallows access for all other users (except root).
+
+.TP
+.B \-n, \-\-no\-allow\-other, \-o no\-allow\-other
+Does not add \fB\-o allow_other\fP to FUSE options.
+This causes the mount to be accessible only by the current user.
+
+
+.SH FILE CREATION POLICY
+New files and directories are created so they are owned by the mounter.
+bindfs can let this happen (the default for normal users),
+or it can try to change the owner to the uid/gid of the process that
+wants to create the file (the default for root).  It is also possible to
+have bindfs try to change the owner to a particular user or group.
+
+.TP
+.B \-\-create\-as\-user, \-o create\-as\-user
+Tries to change the owner and group of new files and directories to the
+uid and gid of the caller. This can work only if the mounter is root.
+It is also the default behavior (mimicing mount \-\-bind) if the mounter is root.
+
+.TP
+.B \-\-create\-as\-mounter, \-o create\-as\-mounter
+All new files and directories will be owned by the mounter.
+This is the default behavior for non\-root mounters.
+
+.TP
+.B \-\-create\-for\-user=\fIuser\fP, \-o create\-for\-user=...
+Tries to change the owner of new files and directories to the user
+specified here.  This can work only if the mounter is root.  This
+option overrides the \-\-create\-as\-user and \-\-create\-as\-mounter options.
+
+.TP
+.B \-\-create\-for\-group=\fIgroup\fP, \-o create\-for\-group=...
+Tries to change the owning group of new files and directories to the 
+group specified here.  This can work only if the mounter is root.  This
+option overrides the \-\-create\-as\-user and \-\-create\-as\-mounter options.
+
+.TP
+.B \-\-create\-with\-perms=\fIpermissions\fP, \-o create\-with\-perms=...
+Works like \-\-perms but is applied to the permission bits of new files
+get in the source directory.
+Normally the permissions of new files depend on the creating process's
+preferences and umask.
+This option can be used to modify those permissions or override
+them completely.
+See \fB\%PERMISSION \%SPECIFICATION\fP below for details.
+
+
+.SH CHOWN/CHGRP POLICY
+The behaviour on chown/chgrp calls can be changed. By default they are passed
+through to the source directory even if bindfs is set to show
+a fake owner/group. A chown/chgrp call will only succeed if the user has
+enough mirrored permissions to chmod the mirrored file AND
+the mounter has enough permissions to chmod the real file.
+
+.TP
+.B \-\-chown\-normal, \-o chown\-normal
+Tries to chown the underlying file. This is the default.
+
+.TP
+.B \-\-chown\-ignore, \-o chown\-ignore
+Lets chown succeed (if the user has enough mirrored permissions)
+but actually does nothing. A combined chown/chgrp is effectively turned
+into a chgrp-only request.
+
+.TP
+.B \-\-chown\-deny, \-o chown\-deny
+Makes chown always fail with a 'permission denied' error.
+A combined chown/chgrp request will fail as well.
+
+.TP
+.B \-\-chgrp\-normal, \-o chgrp\-normal
+Tries to chgrp the underlying file. This is the default.
+
+.TP
+.B \-\-chgrp\-ignore, \-o chgrp\-ignore
+Lets chgrp succeed (if the user has enough mirrored permissions)
+but actually does nothing. A combined chown/chgrp is effectively turned into a
+chown-only request.
+
+.TP
+.B \-\-chgrp\-deny, \-o chgrp\-deny
+Makes chgrp always fail with a 'permission denied' error.
+A combined chown/chgrp request will fail as well.
+
+
+.SH CHMOD POLICY
+Chmod calls are forwarded to the source directory by default.
+This may cause unexpected behaviour if bindfs is altering permission bits.
+
+.TP
+.B \-\-chmod\-normal, \-o chmod\-normal
+Tries to chmod the underlying file. This will succeed if the user has
+the appropriate mirrored permissions to chmod the mirrored file AND
+the mounter has enough permissions to chmod the real file.
+This is the default (in order to behave like mount \-\-bind by default).
+
+.TP
+.B \-\-chmod\-ignore, \-o chmod\-ignore
+Lets chmod succeed (if the user has enough mirrored permissions)
+but actually does nothing.
+
+.TP
+.B \-\-chmod\-deny, \-o chmod\-deny
+Makes chmod always fail with a 'permission denied' error.
+
+.TP
+.B \-\-chmod\-allow\-x, \-o chmod\-allow\-x
+Allows setting and clearing the executable attribute on files
+(but not directories). When used with \-\-chmod\-ignore,
+chmods will only affect execute bits on files and changes to other bits are
+discarded.
+With \-\-chmod\-deny, all chmods that would change any bits except
+excecute bits on files will still fail with a 'permission denied'.
+This option does nothing with \-\-chmod\-normal.
+
+
+.SH XATTR POLICY
+Extended attributes are mirrored by default,
+though not all underlying file systems support xattrs.
+
+.TP
+.B \-\-xattr\-none, \-o xattr\-none
+Disable extended attributes altogether. All operations will
+return 'Operation not supported'.
+
+.TP
+.B \-\-xattr\-ro, \-o xattr\-ro
+Let extended attributes be read\-only.
+
+.TP
+.B \-\-xattr\-rw, \-o xattr\-rw
+Let extended attributes be read\-write (the default).
+The read/write permissions are checked against the (possibly modified)
+file permissions inside the mount.
+
+
+.SH TIME-RELATED OPTIONS
+
+Recall that a unix file has three standard timestamps:
+\fBatime\fP (last access i.e. read time),
+\fBmtime\fP (last content modification time)
+\fBctime\fP (last content or metadata (inode) change time)
+
+It may sometimes be useful to alter these timestamps, but care should be taken
+not to cause programs (e.g. backup jobs) to miss important changes.
+
+.TP
+.B \-\-ctime\-from-mtime, \-o ctime\-from\-mtime
+Reads the ctime of each file and directory from its mtime.
+In other words, only content modifications (as opposed to metadata changes)
+will be reflected in a mirrored file's ctime.
+(The underlying file's ctime will still be updated normally.)
+
+
+.SH FUSE OPTIONS
+.TP
+.B \-o \fIoptions
+Fuse options.
+
+.TP
+.B \-r, \-o ro
+Make the mount strictly read-only.
+This even prevents root from writing to it.
+If this is all you need, then (since Linux 2.6.26) you can get a
+more efficent mount with \fBmount \-\-bind\fP and then \fBmount \-o remount,ro\fP.
+
+.TP
+.B \-d, \-o debug
+Enable debug output (implies \-f).
+
+.TP
+.B \-f
+Foreground operation.
+
+.TP
+.B \-s
+Disable multithreaded operation. bindfs should be thread-safe.
+
+
+.SH PERMISSION SPECIFICATION
+The \fB\-p\fP option takes a comma\- or colon\-separated list of either octal
+numeric permission bits or symbolic representations of permission bit
+operations.
+The symbolic representation is based on that of the  \fBchmod\fP(1) command.
+setuid, setgid and sticky bits are ignored.
+
+This program extends the chmod symbolic representation with the following
+operands:
+
+`\fBD\fP' (right hand side)
+    Works like \fBX\fP but applies only to directories (not to executables).
+
+`\fBd\fP' and `\fBf\fP' (left hand side)
+    Makes this directive only apply to directories (d) or files (f).
+    e.g. \fBgd\-w\fP would remove the group write bit from all directories.
+
+`\fBu\fP', `\fBg\fP', `\fBo\fP' (right hand side)
+    Uses the user (u), group (g) or others (o) permission bits of
+    the original file.
+    e.g. \fBg=u\fP would copy the user's permission bits to the group.
+         \fBug+o\fP would add the others' permissions to the owner and group.
+
+
+.I Examples
+.TP
+.B o\-rwx
+Removes all permission bits from others.
+
+.TP
+.B g=rD
+Allows group to read all files and enter all directories, but nothing else.
+
+.TP
+.B 0644,a+X
+Sets permission bits to 0644 and adds the execute bit for everyone
+to all directories and executables.
+
+.TP
+.B og\-x:og+rD:u=rwX:g+rw
+Removes execute bit for others and group,
+adds read and directory execute for others and group,
+sets user permissions to read, write and execute directory/executable,
+adds read and write for group.
+
+
+.SH EXAMPLES
+.BR
+.TP
+.B bindfs \-u www \-g nogroup \-p 0000,u=rD ~/mywebsite ~/public_html/mysite
+
+Publishes a website in public_html so that only the 'www' user can
+read the site.
+
+.TP
+.B bindfs \-M foo,bar,1007,@mygroup \-p 0600,u+X dir mnt
+
+Gives access to 'foo', 'bar', the user with the UID 1007 as well as
+everyone in the group 'mygroup'. Sets the permission bits to 0600,
+thus giving the specified users read/write access,
+and adds the user execute bit for directories and executables.
+
+.TP
+.B bindfs \-ono\-allow\-other,perms=a\-w somedir somedir
+
+Makes a directory read\-only and accessable only by the current user.
+
+.TP
+.B bindfs#/home/bob/shared /var/www/shared/bob  fuse  perms=0000:u+rD   0   0
+
+An example \fI/etc/fstab\fP entry. Note that the colon must be used to
+separate arguments to perms, because the comma is an option separator in
+\fI/etc/fstab\fP.
+
+
+.SH NOTES
+
+Setuid and setgid bits have no effect inside the mount.
+This is a necessary security feature of FUSE.
+
+MacFuse caches file contents by default.
+This means that changes in source files are not always immediately visible under the mount point.
+\fB\-o nolocalcaches\fP can be used to disable the cache.
+
+.SH BUGS
+
+Please report to the issue tracker on the project home page at
+http://code.google.com/p/bindfs/
+
+
+.SH AUTHOR
+Martin P\[:a]rtel <martin dot partel at gmail dot com>
+
+
+.SH SEE ALSO
+\fBchmod\fP(1), \fBfusermount\fP(1)
+
diff --git a/src/bindfs.c b/src/bindfs.c
new file mode 100644
index 0000000..ff7b35f
--- /dev/null
+++ b/src/bindfs.c
@@ -0,0 +1,1329 @@
+/*
+    Copyright 2006,2007,2008,2009,2010 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+
+
+    This file is based on fusexmp_fh.c from FUSE 2.5.3,
+    which had the following notice:
+    ---
+    FUSE: Filesystem in Userspace
+    Copyright (C) 2001-2006  Miklos Szeredi <miklos@szeredi.hu>
+
+    This program can be distributed under the terms of the GNU GPL.
+    See the file COPYING.
+    ---
+
+*/
+
+#include <config.h>
+
+/* For pread/pwrite */
+#define _XOPEN_SOURCE 500
+
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#include <sys/statvfs.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <errno.h>
+#include <getopt.h>
+#include <assert.h>
+#include <pwd.h>
+#include <grp.h>
+#ifdef HAVE_SETXATTR
+#include <sys/xattr.h>
+#endif
+
+#include <fuse.h>
+#include <fuse_opt.h>
+
+#include "debug.h"
+#include "permchain.h"
+#include "userinfo.h"
+#include "misc.h"
+
+/* SETTINGS */
+static struct settings {
+    const char *progname;
+    struct permchain *permchain; /* permission bit rules. see permchain.h */
+    uid_t new_uid; /* user-specified uid */
+    gid_t new_gid; /* user-specified gid */
+    uid_t create_for_uid;
+    gid_t create_for_gid;
+    const char *mntsrc;
+    const char *mntdest;
+    int mntsrc_fd;
+
+    enum CreatePolicy {
+        CREATE_AS_USER,
+        CREATE_AS_MOUNTER
+    } create_policy;
+
+    struct permchain *create_permchain; /* the --create-with-perms option */
+
+    enum ChownPolicy {
+        CHOWN_NORMAL,
+        CHOWN_IGNORE,
+        CHOWN_DENY
+    } chown_policy;
+
+    enum ChgrpPolicy {
+        CHGRP_NORMAL,
+        CHGRP_IGNORE,
+        CHGRP_DENY
+    } chgrp_policy;
+
+    enum ChmodPolicy {
+        CHMOD_NORMAL,
+        CHMOD_IGNORE,
+        CHMOD_DENY
+    } chmod_policy;
+    
+    int chmod_allow_x;
+
+    enum XAttrPolicy {
+        XATTR_UNIMPLEMENTED,
+        XATTR_READ_ONLY,
+        XATTR_READ_WRITE
+    } xattr_policy;
+
+    int mirrored_users_only;
+    uid_t* mirrored_users;
+    int num_mirrored_users;
+    gid_t *mirrored_members;
+    int num_mirrored_members;
+
+    int ctime_from_mtime;
+} settings;
+
+
+
+/* PROTOTYPES */
+
+static int is_mirroring_enabled();
+
+/* Checks whether the uid is to be the mirrored owner of all files. */
+static int is_mirrored_user(uid_t uid);
+
+/* Processes the virtual path to a real path. Don't free() the result. */
+static const char *process_path(const char *path);
+
+/* The common parts of getattr and fgetattr */
+static int getattr_common(const char *path, struct stat *stbuf);
+
+
+/* FUSE callbacks */
+static void *bindfs_init();
+static void bindfs_destroy(void *private_data);
+static int bindfs_getattr(const char *path, struct stat *stbuf);
+static int bindfs_fgetattr(const char *path, struct stat *stbuf,
+                           struct fuse_file_info *fi);
+static int bindfs_readlink(const char *path, char *buf, size_t size);
+static int bindfs_opendir(const char *path, struct fuse_file_info *fi);
+static inline DIR *get_dirp(struct fuse_file_info *fi);
+static int bindfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+                          off_t offset, struct fuse_file_info *fi);
+static int bindfs_releasedir(const char *path, struct fuse_file_info *fi);
+static int bindfs_mknod(const char *path, mode_t mode, dev_t rdev);
+static int bindfs_mkdir(const char *path, mode_t mode);
+static int bindfs_unlink(const char *path);
+static int bindfs_rmdir(const char *path);
+static int bindfs_symlink(const char *from, const char *to);
+static int bindfs_rename(const char *from, const char *to);
+static int bindfs_link(const char *from, const char *to);
+static int bindfs_chmod(const char *path, mode_t mode);
+static int bindfs_chown(const char *path, uid_t uid, gid_t gid);
+static int bindfs_truncate(const char *path, off_t size);
+static int bindfs_ftruncate(const char *path, off_t size,
+                            struct fuse_file_info *fi);
+static int bindfs_utime(const char *path, struct utimbuf *buf);
+static int bindfs_create(const char *path, mode_t mode, struct fuse_file_info *fi);
+static int bindfs_open(const char *path, struct fuse_file_info *fi);
+static int bindfs_read(const char *path, char *buf, size_t size, off_t offset,
+                       struct fuse_file_info *fi);
+static int bindfs_write(const char *path, const char *buf, size_t size,
+                        off_t offset, struct fuse_file_info *fi);
+static int bindfs_statfs(const char *path, struct statvfs *stbuf);
+static int bindfs_release(const char *path, struct fuse_file_info *fi);
+static int bindfs_fsync(const char *path, int isdatasync,
+                        struct fuse_file_info *fi);
+
+
+static void print_usage(const char *progname);
+static void atexit_func();
+static int process_option(void *data, const char *arg, int key,
+                          struct fuse_args *outargs);
+
+static int is_mirroring_enabled()
+{
+    return settings.num_mirrored_users + settings.num_mirrored_members > 0;
+}
+
+static int is_mirrored_user(uid_t uid)
+{
+    int i;
+    for (i = 0; i < settings.num_mirrored_users; ++i) {
+        if (settings.mirrored_users[i] == uid)
+            break;
+    }
+    if (i < settings.num_mirrored_users) { /* found in mirrored_users */
+        return 1;
+    } else {
+        for (i = 0; i < settings.num_mirrored_members; ++i) {
+            if (user_belongs_to_group(uid, settings.mirrored_members[i]))
+                break;
+        }
+        if (i < settings.num_mirrored_members) /* found in mirrored_members */
+            return 1;
+    }
+    return 0;
+}
+
+
+static const char *process_path(const char *path)
+{
+    if (path == NULL) /* possible? */
+        return NULL;
+
+    while (*path == '/')
+        ++path;
+
+    if (*path == '\0')
+        return ".";
+    else
+        return path;
+}
+
+static int getattr_common(const char *procpath, struct stat *stbuf)
+{
+    struct fuse_context *fc = fuse_get_context();
+
+    /* Copy mtime (file content modification time)
+       to ctime (inode/status change time)
+       if the user asked for that */
+    if (settings.ctime_from_mtime)
+        stbuf->st_ctime = stbuf->st_mtime;
+
+    /* Report user-defined owner/group if specified */
+    if (settings.new_uid != -1)
+        stbuf->st_uid = settings.new_uid;
+    if (settings.new_gid != -1)
+        stbuf->st_gid = settings.new_gid;
+
+    /* Mirrored user? */
+    if (is_mirroring_enabled() && is_mirrored_user(fc->uid)) {
+        stbuf->st_uid = fc->uid;
+    } else if (settings.mirrored_users_only && fc->uid != 0) {
+        stbuf->st_mode &= ~0777; /* Deny all access if mirror-only and not root */
+        return 0;
+    }
+
+    if ((stbuf->st_mode & S_IFLNK) == S_IFLNK)
+        return 0; /* don't bother with symlink permissions -- they don't matter */
+
+    /* Apply user-defined permission bit modifications */
+    stbuf->st_mode = permchain_apply(settings.permchain, stbuf->st_mode);
+
+    /* Check that we can really do what we promise */
+    if (access(procpath, R_OK) == -1)
+        stbuf->st_mode &= ~0444;
+    if (access(procpath, W_OK) == -1)
+        stbuf->st_mode &= ~0222;
+    if (access(procpath, X_OK) == -1)
+        stbuf->st_mode &= ~0111;
+
+    return 0;
+}
+
+static void *bindfs_init()
+{
+    assert(settings.permchain != NULL);
+    assert(settings.mntsrc_fd > 0);
+
+    if (fchdir(settings.mntsrc_fd) != 0) {
+        fprintf(
+            stderr,
+            "Could not change working directory to '%s': %s\n",
+            settings.mntsrc,
+            strerror(errno)
+            );
+        fuse_exit(fuse_get_context()->fuse);
+    }
+
+    return NULL;
+}
+
+static void bindfs_destroy(void *private_data)
+{
+}
+
+static int bindfs_getattr(const char *path, struct stat *stbuf)
+{
+    path = process_path(path);
+
+    if (lstat(path, stbuf) == -1)
+        return -errno;
+    return getattr_common(path, stbuf);
+}
+
+static int bindfs_fgetattr(const char *path, struct stat *stbuf,
+                           struct fuse_file_info *fi)
+{
+    path = process_path(path);
+
+    if (fstat(fi->fh, stbuf) == -1)
+        return -errno;
+    return getattr_common(path, stbuf);
+}
+
+static int bindfs_readlink(const char *path, char *buf, size_t size)
+{
+    int res;
+
+    path = process_path(path);
+
+    /* No need to check for access to the link itself, since symlink
+       permissions don't matter. Access to the path components of the symlink
+       are automatically queried by FUSE. */
+
+    res = readlink(path, buf, size - 1);
+    if (res == -1)
+        return -errno;
+
+    buf[res] = '\0';
+    return 0;
+}
+
+static int bindfs_opendir(const char *path, struct fuse_file_info *fi)
+{
+    DIR *dp;
+
+    path = process_path(path);
+
+    dp = opendir(path);
+    if (dp == NULL)
+        return -errno;
+
+    fi->fh = (unsigned long) dp;
+    return 0;
+}
+
+static inline DIR *get_dirp(struct fuse_file_info *fi)
+{
+    return (DIR *) (uintptr_t) fi->fh;
+}
+
+static int bindfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+                          off_t offset, struct fuse_file_info *fi)
+{
+    DIR *dp = get_dirp(fi);
+    struct dirent *de;
+
+    (void) path;
+    seekdir(dp, offset);
+    while ((de = readdir(dp)) != NULL) {
+        struct stat st;
+        memset(&st, 0, sizeof(st));
+        st.st_ino = de->d_ino;
+        st.st_mode = de->d_type << 12;
+        if (filler(buf, de->d_name, &st, telldir(dp)))
+            break;
+    }
+
+    return 0;
+}
+
+static int bindfs_releasedir(const char *path, struct fuse_file_info *fi)
+{
+    DIR *dp = get_dirp(fi);
+    (void) path;
+    closedir(dp);
+    return 0;
+}
+
+static int bindfs_mknod(const char *path, mode_t mode, dev_t rdev)
+{
+    int res;
+    struct fuse_context *fc;
+    uid_t file_owner = -1;
+    gid_t file_group = -1;
+
+    path = process_path(path);
+
+    mode = permchain_apply(settings.create_permchain, mode);
+
+    if (S_ISFIFO(mode))
+        res = mkfifo(path, mode);
+    else
+        res = mknod(path, mode, rdev);
+    if (res == -1)
+        return -errno;
+
+    if (settings.create_policy == CREATE_AS_USER) {
+        fc = fuse_get_context();
+        file_owner = fc->uid;
+        file_group = fc->gid;
+    }
+
+    if (settings.create_for_uid != -1)
+        file_owner = settings.create_for_uid;
+    if (settings.create_for_gid != -1)
+        file_group = settings.create_for_gid;
+
+    if ((file_owner != -1) || (file_group != -1)) {
+        if (chown(path, file_owner, file_group) == -1) {
+            DPRINTF("Failed to chown new device node (%d)", errno);
+        }
+    }
+
+    return 0;
+}
+
+static int bindfs_mkdir(const char *path, mode_t mode)
+{
+    int res;
+    struct fuse_context *fc;
+    uid_t file_owner = -1;
+    gid_t file_group = -1;
+
+    path = process_path(path);
+
+    mode |= S_IFDIR; /* tell permchain_apply this is a directory */
+    mode = permchain_apply(settings.create_permchain, mode);
+
+    res = mkdir(path, mode & 0777);
+    if (res == -1)
+        return -errno;
+
+    if (settings.create_policy == CREATE_AS_USER) {
+        fc = fuse_get_context();
+        file_owner = fc->uid;
+        file_group = fc->gid;
+    }
+
+    if (settings.create_for_uid != -1)
+        file_owner = settings.create_for_uid;
+    if (settings.create_for_gid != -1)
+        file_group = settings.create_for_gid;
+
+    if ((file_owner != -1) || (file_group != -1)) {
+        if (chown(path, file_owner, file_group) == -1) {
+            DPRINTF("Failed to chown new directory (%d)", errno);
+        }
+    }
+
+    return 0;
+}
+
+static int bindfs_unlink(const char *path)
+{
+    int res;
+
+    path = process_path(path);
+
+    res = unlink(path);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_rmdir(const char *path)
+{
+    int res;
+
+    path = process_path(path);
+
+    res = rmdir(path);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_symlink(const char *from, const char *to)
+{
+    int res;
+    struct fuse_context *fc;
+    uid_t file_owner = -1;
+    gid_t file_group = -1;
+
+    to = process_path(to);
+
+    res = symlink(from, to);
+    if (res == -1)
+        return -errno;
+
+    if (settings.create_policy == CREATE_AS_USER) {
+        fc = fuse_get_context();
+        file_owner = fc->uid;
+        file_group = fc->gid;
+    }
+
+    if (settings.create_for_uid != -1)
+        file_owner = settings.create_for_uid;
+    if (settings.create_for_gid != -1)
+        file_group = settings.create_for_gid;
+
+    if ((file_owner != -1) || (file_group != -1)) {
+        if (lchown(to, file_owner, file_group) == -1) {
+            DPRINTF("Failed to lchown new symlink (%d)", errno);
+        }
+    }
+
+    return 0;
+}
+
+static int bindfs_rename(const char *from, const char *to)
+{
+    int res;
+
+    from = process_path(from);
+    to = process_path(to);
+
+    res = rename(from, to);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_link(const char *from, const char *to)
+{
+    int res;
+
+    from = process_path(from);
+    to = process_path(to);
+
+    res = link(from, to);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_chmod(const char *path, mode_t mode)
+{
+    int file_execute_only = 0;
+    struct stat st;
+    mode_t diff = 0;
+
+    path = process_path(path);
+
+    if (settings.chmod_allow_x) {
+        /* Get the old permission bits and see which bits would change. */
+        if (lstat(path, &st) == -1)
+            return -errno;
+
+        if (S_ISREG(st.st_mode)) {
+            diff = (st.st_mode & 07777) ^ (mode & 07777);
+            file_execute_only = 1;
+        }
+    }
+
+    switch (settings.chmod_policy) {
+    case CHMOD_NORMAL:
+        if (chmod(path, mode) == -1)
+            return -errno;
+        return 0;
+    case CHMOD_IGNORE:
+        if (file_execute_only) {
+            diff &= 00111; /* See which execute bits were flipped.
+                              Forget about other differences. */
+            if (chmod(path, st.st_mode ^ diff) == -1)
+                return -errno;
+        }
+        return 0;
+    case CHMOD_DENY:
+        if (file_execute_only) {
+            if ((diff & 07666) == 0) {
+                /* Only execute bits have changed, so we can allow this. */
+                if (chmod(path, mode) == -1)
+                    return -errno;
+                return 0;
+            }
+        }
+        return -EPERM;
+    default:
+        assert(0);
+    }
+}
+
+static int bindfs_chown(const char *path, uid_t uid, gid_t gid)
+{
+    int res;
+
+    if (uid != -1) {
+        switch (settings.chown_policy) {
+        case CHOWN_NORMAL:
+            break;
+        case CHOWN_IGNORE:
+            uid = -1;
+            break;
+        case CHOWN_DENY:
+            return -EPERM;
+        }
+    }
+    
+    if (gid != -1) {
+        switch (settings.chgrp_policy) {
+        case CHGRP_NORMAL:
+            break;
+        case CHGRP_IGNORE:
+            gid = -1;
+            break;
+        case CHGRP_DENY:
+            return -EPERM;
+        }
+    }
+
+    if (uid != -1 || gid != -1) {
+        path = process_path(path);
+        res = lchown(path, uid, gid);
+        if (res == -1)
+            return -errno;
+    }
+
+    return 0;
+}
+
+static int bindfs_truncate(const char *path, off_t size)
+{
+    int res;
+
+    path = process_path(path);
+
+    res = truncate(path, size);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_ftruncate(const char *path, off_t size,
+                            struct fuse_file_info *fi)
+{
+    int res;
+
+    (void) path;
+
+    res = ftruncate(fi->fh, size);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_utime(const char *path, struct utimbuf *buf)
+{
+    int res;
+
+    path = process_path(path);
+
+    res = utime(path, buf);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_create(const char *path, mode_t mode, struct fuse_file_info *fi)
+{
+    int fd;
+    struct fuse_context *fc;
+    uid_t file_owner = -1;
+    gid_t file_group = -1;
+
+    path = process_path(path);
+
+    mode |= S_IFREG; /* tell permchain_apply this is a regular file */
+    mode = permchain_apply(settings.create_permchain, mode);
+
+    fd = open(path, fi->flags, mode & 0777);
+    if (fd == -1)
+        return -errno;
+
+    if (settings.create_policy == CREATE_AS_USER) {
+        fc = fuse_get_context();
+        file_owner = fc->uid;
+        file_group = fc->gid;
+    }
+
+    if (settings.create_for_uid != -1)
+        file_owner = settings.create_for_uid;
+    if (settings.create_for_gid != -1)
+        file_group = settings.create_for_gid;
+
+    if ((file_owner != -1) || (file_group != -1)) {
+        if (chown(path, file_owner, file_group) == -1) {
+            DPRINTF("Failed to chown new file (%d)", errno);
+        }
+    }
+
+    fi->fh = fd;
+    return 0;
+}
+
+static int bindfs_open(const char *path, struct fuse_file_info *fi)
+{
+    int fd;
+
+    path = process_path(path);
+
+    fd = open(path, fi->flags);
+    if (fd == -1)
+        return -errno;
+
+    fi->fh = fd;
+    return 0;
+}
+
+static int bindfs_read(const char *path, char *buf, size_t size, off_t offset,
+                       struct fuse_file_info *fi)
+{
+    int res;
+
+    (void) path;
+    res = pread(fi->fh, buf, size, offset);
+    if (res == -1)
+        res = -errno;
+
+    return res;
+}
+
+static int bindfs_write(const char *path, const char *buf, size_t size,
+                        off_t offset, struct fuse_file_info *fi)
+{
+    int res;
+
+    (void) path;
+    res = pwrite(fi->fh, buf, size, offset);
+    if (res == -1)
+        res = -errno;
+
+    return res;
+}
+
+static int bindfs_statfs(const char *path, struct statvfs *stbuf)
+{
+    int res;
+
+    path = process_path(path);
+
+    res = statvfs(path, stbuf);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int bindfs_release(const char *path, struct fuse_file_info *fi)
+{
+    (void) path;
+    close(fi->fh);
+
+    return 0;
+}
+
+static int bindfs_fsync(const char *path, int isdatasync,
+                        struct fuse_file_info *fi)
+{
+    int res;
+    (void) path;
+
+#ifndef HAVE_FDATASYNC
+    (void) isdatasync;
+#else
+    if (isdatasync)
+        res = fdatasync(fi->fh);
+    else
+#endif
+        res = fsync(fi->fh);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+#ifdef HAVE_SETXATTR
+/* If HAVE_L*XATTR is not defined, we assume Mac/BSD -style *xattr() */
+
+static int bindfs_setxattr(const char *path, const char *name, const char *value,
+                           size_t size, int flags)
+{
+    DPRINTF("setxattr %s %s=%s", path, name, value);
+    
+    if (settings.xattr_policy == XATTR_READ_ONLY)
+        return -EACCES;
+
+    /* fuse checks permissions for us */
+    path = process_path(path);
+#ifdef HAVE_LSETXATTR
+    if (lsetxattr(path, name, value, size, flags) == -1)
+#else
+    if (setxattr(path, name, value, size, 0, flags | XATTR_NOFOLLOW) == -1)
+#endif
+        return -errno;
+    return 0;
+}
+
+static int bindfs_getxattr(const char *path, const char *name, char *value,
+                           size_t size)
+{
+    int res;
+
+    DPRINTF("getxattr %s %s", path, name);
+    
+    path = process_path(path);
+    /* fuse checks permissions for us */
+#ifdef HAVE_LGETXATTR
+    res = lgetxattr(path, name, value, size);
+#else
+    res = getxattr(path, name, value, size, 0, XATTR_NOFOLLOW);
+#endif
+    if (res == -1)
+        return -errno;
+    return res;
+}
+
+static int bindfs_listxattr(const char *path, char *list, size_t size)
+{
+    int res;
+
+    DPRINTF("listxattr %s", path);
+    
+    path = process_path(path);
+    /* fuse checks permissions for us */
+#ifdef HAVE_LLISTXATTR
+    res = llistxattr(path, list, size);
+#else
+    res = listxattr(path, list, size, XATTR_NOFOLLOW);
+#endif
+    if (res == -1)
+        return -errno;
+    return res;
+}
+
+static int bindfs_removexattr(const char *path, const char *name)
+{
+    DPRINTF("removexattr %s %s", path, name);
+
+    if (settings.xattr_policy == XATTR_READ_ONLY)
+        return -EACCES;
+
+    path = process_path(path);
+    /* fuse checks permissions for us */
+#ifdef HAVE_LREMOVEXATTR
+    if (lremovexattr(path, name) == -1)
+#else
+    if (removexattr(path, name, XATTR_NOFOLLOW) == -1)
+#endif
+        return -errno;
+    return 0;
+}
+#endif /* HAVE_SETXATTR */
+
+
+static struct fuse_operations bindfs_oper = {
+    .init       = bindfs_init,
+    .destroy    = bindfs_destroy,
+    .getattr    = bindfs_getattr,
+    .fgetattr   = bindfs_fgetattr,
+    /* no access() since we always use -o default_permissions */
+    .readlink   = bindfs_readlink,
+    .opendir    = bindfs_opendir,
+    .readdir    = bindfs_readdir,
+    .releasedir = bindfs_releasedir,
+    .mknod      = bindfs_mknod,
+    .mkdir      = bindfs_mkdir,
+    .symlink    = bindfs_symlink,
+    .unlink     = bindfs_unlink,
+    .rmdir      = bindfs_rmdir,
+    .rename     = bindfs_rename,
+    .link       = bindfs_link,
+    .chmod      = bindfs_chmod,
+    .chown      = bindfs_chown,
+    .truncate   = bindfs_truncate,
+    .ftruncate  = bindfs_ftruncate,
+    .utime      = bindfs_utime,
+    .create     = bindfs_create,
+    .open       = bindfs_open,
+    .read       = bindfs_read,
+    .write      = bindfs_write,
+    .statfs     = bindfs_statfs,
+    .release    = bindfs_release,
+    .fsync      = bindfs_fsync,
+#ifdef HAVE_SETXATTR
+    .setxattr   = bindfs_setxattr,
+    .getxattr   = bindfs_getxattr,
+    .listxattr  = bindfs_listxattr,
+    .removexattr= bindfs_removexattr,
+#endif
+};
+
+static void print_usage(const char *progname)
+{
+    if (progname == NULL)
+        progname = "bindfs";
+
+    printf("\n"
+           "Usage: %s [options] dir mountpoint\n"
+           "Information:\n"
+           "  -h      --help            Print this and exit.\n"
+           "  -V      --version         Print version number and exit.\n"
+           "\n"
+           "Options:\n"
+           "  -u      --user, --owner   Set file owner.\n"
+           "  -g      --group           Set file group.\n"
+           "  -m      --mirror          Comma-separated list of users who will see\n"
+           "                            themselves as the owners of all files.\n"
+           "  -M      --mirror-only     Like --mirror but disallow access for\n"
+           "                            all other users.\n"
+           "  -n      --no-allow-other  Do not add -o allow_other to fuse options.\n"
+           "\n"
+           "Permission bits:\n"
+           "  -p      --perms           Specify permissions, similar to chmod\n"
+           "                            e.g. og-x,og+rD,u=rwX,g+rw  or  0644,a+X\n"
+           "\n"
+           "File creation policy:\n"
+           "  --create-as-user          New files owned by creator (default for root). *\n"
+           "  --create-as-mounter       New files owned by fs mounter (default for users).\n"
+           "  --create-for-user         New files owned by specified user. *\n"
+           "  --create-for-group        New files owned by specified group. *\n"
+           "  --create-with-perms       Alter permissions of new files.\n"
+           "\n"
+           "Chown policy:\n"
+           "  --chown-normal            Try to chown the original files (the default).\n"
+           "  --chown-ignore            Have all chowns fail silently.\n"
+           "  --chown-deny              Have all chowns fail with 'permission denied'.\n"
+           "\n"
+           "Chgrp policy:\n"
+           "  --chgrp-normal            Try to chgrp the original files (the default).\n"
+           "  --chgrp-ignore            Have all chgrps fail silently.\n"
+           "  --chgrp-deny              Have all chgrps fail with 'permission denied'.\n"
+           "\n"
+           "Chmod policy:\n"
+           "  --chmod-normal            Try to chmod the original files (the default).\n"
+           "  --chmod-ignore            Have all chmods fail silently.\n"
+           "  --chmod-deny              Have all chmods fail with 'permission denied'.\n"
+           "  --chmod-allow-x           Allow changing file execute bits in any case.\n"
+           "\n"
+           "Extended attribute policy:\n"
+           "  --xattr-none              Do not implement xattr operations.\n"
+           "  --xattr-ro                Read-only xattr operations.\n"
+           "  --xattr-rw                Read-write xattr operations (the default).\n"
+           "\n"
+           "Time-related:\n"
+           "  --ctime-from-mtime        Read file properties' change time\n"
+           "                            from file content modification time.\n"
+           "\n"
+           "FUSE options:\n"
+           "  -o opt[,opt,...]          Mount options.\n"
+           "  -r      -o ro             Mount strictly read-only.\n"
+           "  -d      -o debug          Enable debug output (implies -f).\n"
+           "  -f                        Foreground operation.\n"
+           "  -s                        Disable multithreaded operation.\n"
+           "\n"
+           "(*: root only)\n"
+           "\n",
+           progname);
+}
+
+
+static void atexit_func()
+{
+    permchain_destroy(settings.permchain);
+    settings.permchain = NULL;
+    permchain_destroy(settings.create_permchain);
+    settings.create_permchain = NULL;
+    free(settings.mirrored_users);
+    settings.mirrored_users = NULL;
+    free(settings.mirrored_members);
+    settings.mirrored_members = NULL;
+}
+
+enum OptionKey {
+    OPTKEY_NONOPTION = -2,
+    OPTKEY_UNKNOWN = -1,
+    OPTKEY_HELP,
+    OPTKEY_VERSION,
+    OPTKEY_CREATE_AS_USER,
+    OPTKEY_CREATE_AS_MOUNTER,
+    OPTKEY_CHOWN_NORMAL,
+    OPTKEY_CHOWN_IGNORE,
+    OPTKEY_CHOWN_DENY,
+    OPTKEY_CHGRP_NORMAL,
+    OPTKEY_CHGRP_IGNORE,
+    OPTKEY_CHGRP_DENY,
+    OPTKEY_CHMOD_NORMAL,
+    OPTKEY_CHMOD_IGNORE,
+    OPTKEY_CHMOD_DENY,
+    OPTKEY_CHMOD_ALLOW_X,
+    OPTKEY_XATTR_NONE,
+    OPTKEY_XATTR_READ_ONLY,
+    OPTKEY_XATTR_READ_WRITE,
+    OPTKEY_CTIME_FROM_MTIME
+};
+
+static int process_option(void *data, const char *arg, int key,
+                          struct fuse_args *outargs)
+{
+    switch ((enum OptionKey)key)
+    {
+    case OPTKEY_HELP:
+        print_usage(my_basename(settings.progname));
+        exit(0);
+
+    case OPTKEY_VERSION:
+        printf("%s\n", PACKAGE_STRING);
+        exit(0);
+
+    case OPTKEY_CREATE_AS_USER:
+        if (getuid() == 0) {
+            settings.create_policy = CREATE_AS_USER;
+        } else {
+            fprintf(stderr, "Error: You need to be root to use --create-as-user !\n");
+            return -1;
+        }
+        return 0;
+    case OPTKEY_CREATE_AS_MOUNTER:
+        settings.create_policy = CREATE_AS_MOUNTER;
+        return 0;
+
+    case OPTKEY_CHOWN_NORMAL:
+        settings.chown_policy = CHOWN_NORMAL;
+        return 0;
+    case OPTKEY_CHOWN_IGNORE:
+        settings.chown_policy = CHOWN_IGNORE;
+        return 0;
+    case OPTKEY_CHOWN_DENY:
+        settings.chown_policy = CHOWN_DENY;
+        return 0;
+
+    case OPTKEY_CHGRP_NORMAL:
+        settings.chgrp_policy = CHGRP_NORMAL;
+        return 0;
+    case OPTKEY_CHGRP_IGNORE:
+        settings.chgrp_policy = CHGRP_IGNORE;
+        return 0;
+    case OPTKEY_CHGRP_DENY:
+        settings.chgrp_policy = CHGRP_DENY;
+        return 0;
+
+    case OPTKEY_CHMOD_NORMAL:
+        settings.chmod_policy = CHMOD_NORMAL;
+        return 0;
+    case OPTKEY_CHMOD_IGNORE:
+        settings.chmod_policy = CHMOD_IGNORE;
+        return 0;
+    case OPTKEY_CHMOD_DENY:
+        settings.chmod_policy = CHMOD_DENY;
+        return 0;
+
+    case OPTKEY_CHMOD_ALLOW_X:
+        settings.chmod_allow_x = 1;
+        return 0;
+
+    case OPTKEY_XATTR_NONE:
+        settings.xattr_policy = XATTR_UNIMPLEMENTED;
+        return 0;
+    case OPTKEY_XATTR_READ_ONLY:
+        settings.xattr_policy = XATTR_READ_ONLY;
+        return 0;
+    case OPTKEY_XATTR_READ_WRITE:
+        settings.xattr_policy = XATTR_READ_WRITE;
+        return 0;
+
+    case OPTKEY_CTIME_FROM_MTIME:
+        settings.ctime_from_mtime = 1;
+	return 0;
+
+    case OPTKEY_NONOPTION:
+        if (!settings.mntsrc) {
+            settings.mntsrc = arg;
+            return 0;
+        } else if (!settings.mntdest) {
+            settings.mntdest = arg;
+            return 1; /* leave this argument for fuse_main */
+        } else {
+            fprintf(stderr, "Too many arguments given\n");
+            return -1;
+        }
+
+    default:
+        return 1;
+    }
+}
+
+
+int main(int argc, char *argv[])
+{
+    struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
+
+    /* Fuse's option parser will store things here. */
+    static struct OptionData {
+        char *user;
+        char *group;
+        char *perms;
+        char *mirror;
+        char *mirror_only;
+        char *create_for_user;
+        char *create_for_group;
+        char *create_with_perms;
+        int no_allow_other;
+    } od = {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0};
+
+    #define OPT2(one, two, key) \
+            FUSE_OPT_KEY(one, key), \
+            FUSE_OPT_KEY(two, key)
+    #define OPT_OFFSET2(one, two, offset, key) \
+            {one, offsetof(struct OptionData, offset), key}, \
+            {two, offsetof(struct OptionData, offset), key}
+    #define OPT_OFFSET3(one, two, three, offset, key) \
+            {one, offsetof(struct OptionData, offset), key}, \
+            {two, offsetof(struct OptionData, offset), key}, \
+            {three, offsetof(struct OptionData, offset), key}
+    static const struct fuse_opt options[] = {
+        OPT2("-h", "--help", OPTKEY_HELP),
+        OPT2("-V", "--version", OPTKEY_VERSION),
+        OPT_OFFSET2("-u %s", "--user=%s",              user, -1),
+        OPT_OFFSET2(         "--owner=%s", "owner=%s", user, -1),
+        OPT_OFFSET3("-g %s", "--group=%s", "group=%s", group, -1),
+        OPT_OFFSET3("-p %s", "--perms=%s", "perms=%s", perms, -1),
+        OPT_OFFSET3("-m %s", "--mirror=%s", "mirror=%s", mirror, -1),
+        OPT_OFFSET3("-M %s", "--mirror-only=%s", "mirror-only=%s", mirror_only, -1),
+        OPT_OFFSET3("-n", "--no-allow-other", "no-allow-other", no_allow_other, -1),
+        OPT2("--create-as-user", "create-as-user", OPTKEY_CREATE_AS_USER),
+        OPT2("--create-as-mounter", "create-as-mounter", OPTKEY_CREATE_AS_MOUNTER),
+        OPT_OFFSET2("--create-for-user=%s", "create-for-user=%s", create_for_user, -1),
+        OPT_OFFSET2("--create-for-group=%s", "create-for-group=%s", create_for_group, -1),
+        OPT_OFFSET2("--create-with-perms=%s", "create-with-perms=%s", create_with_perms, -1),
+        OPT2("--chown-normal", "chown-normal", OPTKEY_CHOWN_NORMAL),
+        OPT2("--chown-ignore", "chown-ignore", OPTKEY_CHOWN_IGNORE),
+        OPT2("--chown-deny", "chown-deny", OPTKEY_CHOWN_DENY),
+        OPT2("--chgrp-normal", "chgrp-normal", OPTKEY_CHGRP_NORMAL),
+        OPT2("--chgrp-ignore", "chgrp-ignore", OPTKEY_CHGRP_IGNORE),
+        OPT2("--chgrp-deny", "chgrp-deny", OPTKEY_CHGRP_DENY),
+        OPT2("--chmod-normal", "chmod-normal", OPTKEY_CHMOD_NORMAL),
+        OPT2("--chmod-ignore", "chmod-ignore", OPTKEY_CHMOD_IGNORE),
+        OPT2("--chmod-deny", "chmod-deny", OPTKEY_CHMOD_DENY),
+        OPT2("--chmod-allow-x", "chmod-allow-x", OPTKEY_CHMOD_ALLOW_X),
+        OPT2("--xattr-none", "xattr-none", OPTKEY_XATTR_NONE),
+        OPT2("--xattr-ro", "xattr-ro", OPTKEY_XATTR_READ_ONLY),
+        OPT2("--xattr-rw", "xattr-rw", OPTKEY_XATTR_READ_WRITE),
+        OPT2("--ctime-from-mtime", "ctime-from-mtime", OPTKEY_CTIME_FROM_MTIME),
+        FUSE_OPT_END
+    };
+
+    /* General-purpose variables */
+    int i, j;
+    char *p, *tmpstr;
+
+    int fuse_main_return;
+
+
+    /* Initialize settings */
+    settings.progname = argv[0];
+    settings.permchain = permchain_create();
+    settings.new_uid = -1;
+    settings.new_gid = -1;
+    settings.create_for_uid = -1;
+    settings.create_for_gid = -1;
+    settings.mntsrc = NULL;
+    settings.mntdest = NULL;
+    settings.create_policy = (getuid() == 0) ? CREATE_AS_USER : CREATE_AS_MOUNTER;
+    settings.create_permchain = permchain_create();
+    settings.chown_policy = CHOWN_NORMAL;
+    settings.chgrp_policy = CHGRP_NORMAL;
+    settings.chmod_policy = CHMOD_NORMAL;
+    settings.chmod_allow_x = 0;
+    settings.xattr_policy = XATTR_READ_WRITE;
+    settings.mirrored_users_only = 0;
+    settings.mirrored_users = NULL;
+    settings.num_mirrored_users = 0;
+    settings.mirrored_members = NULL;
+    settings.num_mirrored_members = 0;
+    settings.ctime_from_mtime = 0;
+    atexit(&atexit_func);
+
+    /* Parse options */
+    if (fuse_opt_parse(&args, &od, options, &process_option) == -1)
+        return 1;
+
+    /* Check that a source directory and a mount point was given */
+    if (!settings.mntsrc || !settings.mntdest) {
+        print_usage(my_basename(argv[0]));
+        return 1;
+    }
+
+    /* Parse new owner and group */
+    if (od.user) {
+        if (!user_uid(od.user, &settings.new_uid)) {
+            fprintf(stderr, "Not a valid user ID: %s\n", od.user);
+            return 1;
+        }
+    }
+    if (od.group) {
+        if (!group_gid(od.group, &settings.new_gid)) {
+            fprintf(stderr, "Not a valid group ID: %s\n", od.group);
+            return 1;
+        }
+    }
+
+    /* Parse user and group for new creates */
+    if (od.create_for_user) {
+        if (getuid() != 0) {
+            fprintf(stderr, "Error: You need to be root to use --create-for-user !\n");
+            return 1;
+        }
+        if (!user_uid(od.create_for_user, &settings.create_for_uid)) {
+            fprintf(stderr, "Not a valid user ID: %s\n", od.create_for_user);
+            return 1;
+        }
+    }
+    if (od.create_for_group) {
+        if (getuid() != 0) {
+            fprintf(stderr, "Error: You need to be root to use --create-for-group !\n");
+            return 1;
+        }
+        if (!group_gid(od.create_for_group, &settings.create_for_gid)) {
+            fprintf(stderr, "Not a valid group ID: %s\n", od.create_for_group);
+            return 1;
+        }
+    }
+
+    /* Parse mirrored users and groups */
+    if (od.mirror && od.mirror_only) {
+        fprintf(stderr, "Cannot specify both -m|--mirror and -M|--mirror-only\n");
+        return 1;
+    }
+    if (od.mirror_only) {
+        settings.mirrored_users_only = 1;
+        od.mirror = od.mirror_only;
+    }
+    if (od.mirror) {
+        settings.num_mirrored_users = count_chars(od.mirror, ',') +
+                                      count_chars(od.mirror, ':') + 1;
+        settings.num_mirrored_members = ((*od.mirror == '@') ? 1 : 0) +
+                                        count_substrs(od.mirror, ",@") +
+                                        count_substrs(od.mirror, ":@");
+        settings.num_mirrored_users -= settings.num_mirrored_members;
+        settings.mirrored_users = malloc(settings.num_mirrored_users*sizeof(uid_t));
+        settings.mirrored_members = malloc(settings.num_mirrored_members*sizeof(gid_t));
+
+        i = 0; /* iterate over mirrored_users */
+        j = 0; /* iterate over mirrored_members */
+        p = od.mirror;
+        while (i < settings.num_mirrored_users || j < settings.num_mirrored_members) {
+            tmpstr = strdup_until(p, ",:");
+
+            if (*tmpstr == '@') { /* This is a group name */
+                if (!group_gid(tmpstr + 1, &settings.mirrored_members[j++])) {
+                    fprintf(stderr, "Invalid group ID: '%s'\n", tmpstr + 1);
+                    free(tmpstr);
+                    return 1;
+                }
+            } else {
+                if (!user_uid(tmpstr, &settings.mirrored_users[i++])) {
+                    fprintf(stderr, "Invalid user ID: '%s'\n", tmpstr);
+                    free(tmpstr);
+                    return 1;
+                }
+            }
+            free(tmpstr);
+
+            while (*p != '\0' && *p != ',' && *p != ':')
+                ++p;
+            if (*p != '\0')
+                ++p;
+            else {
+                /* Done. The counters should match. */
+                assert(i == settings.num_mirrored_users);
+                assert(j == settings.num_mirrored_members);
+            }
+        }
+    }
+
+    /* Parse permission bits */
+    if (od.perms) {
+        if (add_chmod_rules_to_permchain(od.perms, settings.permchain) != 0) {
+            fprintf(stderr, "Invalid permission specification: '%s'\n", od.perms);
+            return 1;
+        }
+    }
+    if (od.create_with_perms) {
+        if (add_chmod_rules_to_permchain(od.create_with_perms, settings.create_permchain) != 0) {
+            fprintf(stderr, "Invalid permission specification: '%s'\n", od.create_with_perms);
+            return 1;
+        }
+    }
+
+
+    /* Add default fuse options */
+    if (!od.no_allow_other) {
+        fuse_opt_add_arg(&args, "-oallow_other");
+    }
+
+    /* We want the kernel to do our access checks for us based on what getattr gives it. */
+    fuse_opt_add_arg(&args, "-odefault_permissions");
+    
+    /* We need to disable the attribute cache whenever two users
+       can see different attributes. For now, only mirroring can do that. */
+    if (is_mirroring_enabled()) {
+        fuse_opt_add_arg(&args, "-oattr_timeout=0");
+    }
+
+    /* If the mount source and destination directories are the same
+       then don't require that the directory be empty. */
+    if (strcmp(settings.mntsrc, settings.mntdest) == 0)
+        fuse_opt_add_arg(&args, "-ononempty");
+
+    /* Open mount source for chrooting in bindfs_init */
+    settings.mntsrc_fd = open(settings.mntsrc, O_RDONLY);
+    if (settings.mntsrc_fd == -1) {
+        fprintf(stderr, "Could not open source directory\n");
+        return 1;
+    }
+
+    /* Ignore the umask of the mounter on file creation */
+    umask(0);
+
+    /* Remove xattr implementation if the user doesn't want it */
+    if (settings.xattr_policy == XATTR_UNIMPLEMENTED) {
+        bindfs_oper.setxattr = NULL;
+        bindfs_oper.getxattr = NULL;
+        bindfs_oper.listxattr = NULL;
+        bindfs_oper.removexattr = NULL;
+    }
+
+    fuse_main_return = fuse_main(args.argc, args.argv, &bindfs_oper);
+
+    fuse_opt_free_args(&args);
+    close(settings.mntsrc_fd);
+
+    return fuse_main_return;
+}
diff --git a/src/debug.h b/src/debug.h
new file mode 100644
index 0000000..1883101
--- /dev/null
+++ b/src/debug.h
@@ -0,0 +1,33 @@
+/*
+    Copyright 2006,2007,2008 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef INC_BINDFS_DEBUG_H
+#define INC_BINDFS_DEBUG_H
+
+#include <config.h>
+
+#if BINDFS_DEBUG
+#include <stdio.h>
+#define DPRINTF(fmt, ...) fprintf(stderr, "DEBUG: " fmt "\n", __VA_ARGS__)
+#else
+#define DPRINTF(...)
+#endif
+
+#endif
+
diff --git a/src/misc.c b/src/misc.c
new file mode 100644
index 0000000..0280f61
--- /dev/null
+++ b/src/misc.c
@@ -0,0 +1,83 @@
+/*
+    Copyright 2006,2007,2008 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "misc.h"
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+int count_chars(const char *s, char ch)
+{
+    int count = 0;
+    assert(s != NULL);
+    while (*s != '\0') {
+        if (*s == ch)
+            ++count;
+        ++s;
+    }
+    return count;
+}
+
+int count_substrs(const char *s, const char *sub)
+{
+    int count = 0;
+    int sublen = strlen(sub);
+    int left = strlen(s);
+
+    assert(s != NULL && sub != NULL);
+
+    while (left > sublen) {
+        if (strncmp(s, sub, sublen) == 0)
+            ++count;
+        --left;
+        ++s;
+    }
+
+    return count;
+}
+
+char *strdup_until(const char *s, const char *endchars)
+{
+    char *endloc = strpbrk(s, endchars);
+    char *ret;
+    if (!endloc) {
+        ret = malloc((strlen(s) + 1) * sizeof(char));
+        strcpy(ret, s);
+        return ret;
+    } else {
+        ret = malloc((endloc - s + 1) * sizeof(char));
+        memcpy(ret, s, (endloc - s) * sizeof(char));
+        ret[(endloc - s)] = '\0';
+        return ret;
+    }
+}
+
+const char *my_basename(const char *path)
+{
+    const char *p;
+
+    if (path == NULL)
+        return NULL;
+
+    p = strrchr(path, '/');
+    if (p != NULL)
+        return p + 1;
+    else
+        return path;
+}
diff --git a/src/misc.h b/src/misc.h
new file mode 100644
index 0000000..404c76a
--- /dev/null
+++ b/src/misc.h
@@ -0,0 +1,40 @@
+/*
+    Copyright 2006,2007,2008 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef INC_BINDFS_MISC_H
+#define INC_BINDFS_MISC_H
+
+/* Counts the number of times ch occurs in s. */
+int count_chars(const char *s, char ch);
+
+/* Counts the number of times sub occurs in s. */
+int count_substrs(const char *s, const char *sub);
+
+/* Creates a duplicate string of all the characters in s before
+   an end character is reached. */
+char *strdup_until(const char *s, const char *endchars);
+
+/* Returns a pointer to the first character after the
+   final slash of path, or path itself if it contains no slashes.
+   If the path ends with a slash, then the result is an empty
+   string.
+   Returns NULL if path is NULL. */
+const char *my_basename(const char *path);
+
+#endif
diff --git a/src/permchain.c b/src/permchain.c
new file mode 100644
index 0000000..6e99e7b
--- /dev/null
+++ b/src/permchain.c
@@ -0,0 +1,325 @@
+/*
+    Copyright 2006,2007,2008 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "permchain.h"
+#include <assert.h>
+#include <string.h>
+#include <ctype.h>
+#include "misc.h"
+#include "debug.h"
+
+/* constants for permchain->flags */
+#define PC_APPLY_FILES 1
+#define PC_APPLY_DIRS 2
+#define PC_FLAGS_DEFAULT ((PC_APPLY_FILES) | (PC_APPLY_DIRS))
+
+struct permchain {
+    mode_t mask; /* which permissions to apply to */
+    char op; /* one of '=', '+', '-', 'o' (octal) or '\0' */
+    union {
+        char operands[16]; /* a subset of rwxXstugo */
+        unsigned int octal;
+    };
+    int flags;
+    struct permchain *next;
+};
+
+struct permchain *permchain_create()
+{
+    struct permchain *pc = malloc(sizeof(struct permchain));
+    pc->mask = 0000;
+    pc->op = '\0';
+    memset(pc->operands, '\0', sizeof(pc->operands));
+    pc->next = NULL;
+    pc->flags = PC_FLAGS_DEFAULT;
+    return pc;
+}
+
+
+static int add_chmod_rule_to_permchain(const char *start, const char *end,
+                                       struct permchain *pc);
+static int add_octal_rule_to_permchain(const char *start, const char *end,
+                                       struct permchain *pc);
+static mode_t modebits_to_all(int perms); /* e.g. 5 -> 0555 */
+
+
+
+static int add_chmod_rule_to_permchain(const char *start, const char *end,
+                                       struct permchain *pc)
+{
+    int ret = -1;
+
+    int len = end - start;
+    char *buf = alloca((len + 1) * sizeof(char));
+    const char *p = buf;
+
+    enum {LHS, RHS} state = LHS;
+    struct permchain *newpc = permchain_create();
+    char *operands_ptr = newpc->operands;
+
+    newpc->flags = 0; /* Reset to PC_FLAGS_DEFAULT in the end if not modified */
+
+    memcpy(buf, start, len);
+    buf[len] = '\0';
+
+    while (*p != '\0') {
+        if (state == LHS) {
+            switch (*p) {
+            case 'u':
+                newpc->mask |= 0700;
+                break;
+            case 'g':
+                newpc->mask |= 0070;
+                break;
+            case 'o':
+                newpc->mask |= 0007;
+                break;
+            case 'a':
+                newpc->mask = 0777;
+                break;
+            case 'f':
+                newpc->flags |= PC_APPLY_FILES;
+                break;
+            case 'd':
+                newpc->flags |= PC_APPLY_DIRS;
+                break;
+            case '=':
+            case '+':
+            case '-':
+                if (p == buf) /* first char -> default to 'a' */
+                    newpc->mask = 0777;
+                newpc->op = *p;
+                state = RHS;
+                break;
+            default:
+                goto error;
+            }
+        } else {
+            switch (*p) {
+            case 'r':
+            case 'w':
+            case 'x':
+            case 'X':
+            case 'D':
+            case 's':
+            case 't':
+            case 'u':
+            case 'g':
+            case 'o':
+                if (!strchr(newpc->operands, *p)) {
+                    *(operands_ptr++) = *p;
+                }
+                break;
+            default:
+                goto error;
+            }
+        }
+
+        ++p;
+    }
+
+    ret = 0;
+error:
+    if (newpc->flags == 0)
+        newpc->flags = PC_FLAGS_DEFAULT;
+    if (ret == 0)
+        permchain_cat(pc, newpc);
+    else
+        permchain_destroy(newpc);
+    return ret;
+}
+
+static int add_octal_rule_to_permchain(const char *start, const char *end,
+                                       struct permchain *pc)
+{
+    struct permchain *newpc = permchain_create();
+    long mode = strtol(start, NULL, 8);
+
+    if (mode < 0 || mode > 0777) {
+        permchain_destroy(newpc);
+        return -1;
+    }
+
+    newpc->mask = 0777;
+    newpc->op = 'o';
+    newpc->octal = mode;
+
+    permchain_cat(pc, newpc);
+    return 0;
+}
+
+int add_chmod_rules_to_permchain(const char *rule, struct permchain *pc)
+{
+    int ret = -1;
+    const char *start, *end;
+    struct permchain *newpc = permchain_create();
+
+    assert(rule != 0);
+
+    end = start = rule;
+
+    while (*end != '\0') {
+        /* find delimiter or end of list */
+        while (*end != ',' && *end != ':' && *end != '\0')
+            ++end;
+
+        if (start == end) /* empty rule */
+            goto error;
+
+        assert(start < end);
+
+        if (isdigit(*start)) {
+            if (add_octal_rule_to_permchain(start, end, newpc) != 0)
+                goto error;
+
+        } else {
+            if (add_chmod_rule_to_permchain(start, end, newpc) != 0)
+                goto error;
+        }
+
+        if (*end == ',' || *end == ':')
+            start = ++end;
+    }
+
+    ret = 0;
+error:
+    if (ret == 0)
+        permchain_cat(pc, newpc);
+    else
+        permchain_destroy(newpc);
+    return ret;
+}
+
+void permchain_cat(struct permchain *left, struct permchain *right)
+{
+    while (left->next != NULL)
+        left = left->next;
+    left->next = right;
+}
+
+mode_t modebits_to_all(int perms)
+{
+    mode_t m = perms;
+    m |= perms << 3;
+    m |= perms << 6;
+    return m;
+}
+
+mode_t permchain_apply(struct permchain *pc, mode_t tgtmode)
+{
+    mode_t original_mode = tgtmode;
+    mode_t mode = 0000;
+    const char *p;
+
+    while (pc != NULL) {
+        #if BINDFS_DEBUG
+        if (pc->op == 'o')
+            DPRINTF("STAT MODE: %o, op = %c %o", tgtmode, pc->op, pc->octal);
+        else
+            DPRINTF("STAT MODE: %o, op = %c%s", tgtmode, pc->op, pc->operands);
+        #endif
+
+        if (pc->op == '\0') {
+            pc = pc->next;
+            continue;
+        }
+
+        if ((S_ISDIR(tgtmode) && !(pc->flags & PC_APPLY_DIRS))
+            ||
+            (!S_ISDIR(tgtmode) && !(pc->flags & PC_APPLY_FILES))) {
+
+            pc = pc->next;
+            continue;
+        }
+
+        if (pc->op == '=' || pc->op == '+' || pc->op == '-') {
+
+            mode = 0000;
+
+            for (p = pc->operands; *p != '\0'; ++p) {
+                switch (*p) {
+                case 'r':
+                    mode |= 0444;
+                    break;
+                case 'w':
+                    mode |= 0222;
+                    break;
+                case 'x':
+                    mode |= 0111;
+                    break;
+                case 'X':
+                    if (S_ISDIR(original_mode) || ((original_mode & 0111) != 0))
+                        mode |= 0111;
+                    break;
+                case 'D':
+                    if (S_ISDIR(original_mode))
+                        mode |= 0111;
+                    break;
+                case 's':
+                case 't':
+                    /* ignored */
+                    break;
+                case 'u':
+                    mode |= modebits_to_all((original_mode & 0700) >> 6);
+                    break;
+                case 'g':
+                    mode |= modebits_to_all((original_mode & 0070) >> 3);
+                    break;
+                case 'o':
+                    mode |= modebits_to_all(original_mode & 0007);
+                    break;
+                default:
+                    assert(0);
+                }
+            }
+            mode &= pc->mask;
+        }
+
+        switch (pc->op) {
+        case '=':
+            tgtmode = (tgtmode & ~pc->mask) | mode;
+            break;
+        case '+':
+            tgtmode |= mode;
+            break;
+        case '-':
+            tgtmode &= ~0777 | ~mode;
+            break;
+        case 'o':
+            tgtmode = (tgtmode & ~0777) | pc->octal;
+            break;
+        default:
+            assert(0);
+        }
+        pc = pc->next;
+        DPRINTF("       =>: %o", tgtmode);
+    }
+    return tgtmode;
+}
+
+void permchain_destroy(struct permchain *pc)
+{
+    struct permchain *next;
+    while (pc) {
+        next = pc->next;
+        free(pc);
+        pc = next;
+    }
+}
+
diff --git a/src/permchain.h b/src/permchain.h
new file mode 100644
index 0000000..0f268f0
--- /dev/null
+++ b/src/permchain.h
@@ -0,0 +1,55 @@
+/*
+    Copyright 2006,2007,2008 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef INC_BINDFS_PERMCHAIN_H
+#define INC_BINDFS_PERMCHAIN_H
+
+
+#include <config.h>
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#include <unistd.h>
+
+struct permchain;
+
+struct permchain *permchain_create();
+
+/* Parses chmod arguments like 0777, a=rX, og-rwx etc.
+   Multiple rules may be given, separated with commas or colons.
+   Unlike the ordinary chmod command, the octal specification may be
+   present in a comma/colon-separated list.
+   Returns 0 on success. On failure, pc will not be modified. */
+int add_chmod_rules_to_permchain(const char *rule, struct permchain *pc);
+
+/* Links 'right' to the end of 'left'. Don't destroy 'right' after this. */
+void permchain_cat(struct permchain *left, struct permchain *right);
+
+mode_t permchain_apply(struct permchain *pc, mode_t tgtmode);
+
+void permchain_destroy(struct permchain *pc);
+
+#endif
diff --git a/src/userinfo.c b/src/userinfo.c
new file mode 100644
index 0000000..df0b6e6
--- /dev/null
+++ b/src/userinfo.c
@@ -0,0 +1,177 @@
+/*
+    Copyright 2006,2007,2008 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "userinfo.h"
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+
+int user_uid(const char *username, uid_t *ret)
+{
+    struct passwd pwbuf, *pwbufp = NULL;
+    char *buf;
+    size_t buflen;
+    int res;
+
+    uid_t uid;
+    char *endptr;
+
+    /* Check whether the string is a numerical UID */
+    uid = strtol(username, &endptr, 10);
+    if (*endptr == '\0') {
+        buflen = 1024;
+        buf = malloc(buflen);
+        res = getpwuid_r(uid, &pwbuf, buf, buflen, &pwbufp);
+        if (res != 0) {
+            if (res != ERANGE) { /* don't care if buffer was too small */
+                free(buf);
+                return 0;
+            }
+        }
+        free(buf);
+        *ret = uid;
+        return 1;
+    }
+
+    /* Process user name */
+    buflen = 1024;
+    buf = malloc(buflen);
+
+    res = getpwnam_r(username, &pwbuf, buf, buflen, &pwbufp);
+    while(res == ERANGE) {
+        buflen *= 2;
+        buf = realloc(buf, buflen);
+        res = getpwnam_r(username, &pwbuf, buf, buflen, &pwbufp);
+    }
+
+    if (pwbufp == NULL) {
+        free(buf);
+        return 0;
+    }
+
+    *ret = pwbuf.pw_uid;
+    free(buf);
+    return 1;
+}
+
+
+int group_gid(const char *groupname, gid_t *ret)
+{
+    struct group gbuf, *gbufp = NULL;
+    char *buf;
+    size_t buflen;
+    int res;
+
+    gid_t gid;
+    char *endptr;
+
+    /* Check whether the string is a numerical GID */
+    gid = strtol(groupname, &endptr, 10);
+    if (*endptr == '\0') {
+        buflen = 1024;
+        buf = malloc(buflen);
+        res = getgrgid_r(gid, &gbuf, buf, buflen, &gbufp);
+        if (res != 0) {
+            if (res != ERANGE) { /* don't care if buffer was too small */
+                free(buf);
+                return 0;
+            }
+        }
+        free(buf);
+        *ret = gid;
+        return 1;
+    }
+
+    /* Process group name */
+    buflen = 1024;
+    buf = malloc(buflen);
+
+    res = getgrnam_r(groupname, &gbuf, buf, buflen, &gbufp);
+    while(res == ERANGE) {
+        buflen *= 2;
+        buf = realloc(buf, buflen);
+        res = getgrnam_r(groupname, &gbuf, buf, buflen, &gbufp);
+    }
+
+    if (gbufp == NULL) {
+        free(buf);
+        return 0;
+    }
+
+    *ret = gbuf.gr_gid;
+    free(buf);
+    return 1;
+}
+
+
+int user_belongs_to_group(uid_t uid, gid_t gid)
+{
+    struct passwd pwbuf, *pwbufp = NULL;
+    struct group grbuf, *grbufp = NULL;
+    char *buf;
+    size_t buflen;
+
+    int member;
+    uid_t member_uid;
+
+    int res;
+
+    buflen = 1024;
+    buf = malloc(buflen);
+
+    res = getpwuid_r(uid, &pwbuf, buf, buflen, &pwbufp);
+    while(res == ERANGE) {
+        buflen *= 2;
+        buf = realloc(buf, buflen);
+        res = getpwuid_r(uid, &pwbuf, buf, buflen, &pwbufp);
+    }
+
+    if (pwbufp == NULL)
+        goto no;
+
+    if (gid == pwbuf.pw_gid)
+        goto yes;
+
+    /* we reuse the same buf because we don't need the passwd info any more */
+    res = getgrgid_r(gid, &grbuf, buf, buflen, &grbufp);
+    while(res == ERANGE) {
+        buflen *= 2;
+        buf = realloc(buf, buflen);
+        res = getgrgid_r(gid, &grbuf, buf, buflen, &grbufp);
+    }
+
+    if (grbufp == NULL)
+        goto no;
+
+    for (member = 0; grbuf.gr_mem[member] != NULL; ++member) {
+        if (user_uid(grbuf.gr_mem[member], &member_uid))
+            if (member_uid == uid)
+                goto yes;
+    }
+
+    goto no;
+
+yes:
+    free(buf);
+    return 1;
+no:
+    free(buf);
+    return 0;
+}
diff --git a/src/userinfo.h b/src/userinfo.h
new file mode 100644
index 0000000..26cdb00
--- /dev/null
+++ b/src/userinfo.h
@@ -0,0 +1,39 @@
+/*
+    Copyright 2006,2007,2008 Martin Pärtel <martin.partel@gmail.com>
+
+    This file is part of bindfs.
+
+    bindfs is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    bindfs is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with bindfs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef INC_BINDFS_USERINFO_H
+#define INC_BINDFS_USERINFO_H
+
+#include <config.h>
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#include <pwd.h>
+#include <grp.h>
+
+/* Misc. reentrant helpers for handling user data.
+   Return non-zero on success/true and 0 on failure/false. */
+
+int user_uid(const char *username, uid_t *ret);
+int group_gid(const char *groupname, gid_t *ret);
+
+int user_belongs_to_group(uid_t uid, gid_t gid);
+
+#endif