bring in fusermount

1 files changed, 965 insertions, 0 deletions

diff --git a/contrib/fuse-util/fusermount.c b/contrib/fuse-util/fusermount.c
new file mode 100644
index 00000000000..c3ecc86cc44
--- /dev/null
+++ b/contrib/fuse-util/fusermount.c
@@ -0,0 +1,965 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
+
+  This program can be distributed under the terms of the GNU GPL.
+  See the file COPYING.
+*/
+/* This program does the mounting and unmounting of FUSE filesystems */
+
+#include <config.h>
+
+#include "mount_util.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <mntent.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <sys/fsuid.h>
+#include <sys/socket.h>
+#include <sys/utsname.h>
+
+#define FUSE_COMMFD_ENV		"_FUSE_COMMFD"
+
+#define FUSE_DEV_OLD "/proc/fs/fuse/dev"
+#define FUSE_DEV_NEW "/dev/fuse"
+#define FUSE_VERSION_FILE_OLD "/proc/fs/fuse/version"
+#define FUSE_CONF "/etc/fuse.conf"
+
+#ifndef MS_DIRSYNC
+#define MS_DIRSYNC 128
+#endif
+
+static const char *progname;
+
+static int user_allow_other = 0;
+static int mount_max = 1000;
+
+static const char *get_user_name(void)
+{
+	struct passwd *pw = getpwuid(getuid());
+	if (pw != NULL && pw->pw_name != NULL)
+		return pw->pw_name;
+	else {
+		fprintf(stderr, "%s: could not determine username\n", progname);
+		return NULL;
+	}
+}
+
+static uid_t oldfsuid;
+static gid_t oldfsgid;
+
+static void drop_privs(void)
+{
+	if (getuid() != 0) {
+		oldfsuid = setfsuid(getuid());
+		oldfsgid = setfsgid(getgid());
+	}
+}
+
+static void restore_privs(void)
+{
+	if (getuid() != 0) {
+		setfsuid(oldfsuid);
+		setfsgid(oldfsgid);
+	}
+}
+
+#ifndef IGNORE_MTAB
+static int add_mount(const char *source, const char *mnt, const char *type,
+		     const char *opts)
+{
+	return fuse_mnt_add_mount(progname, source, mnt, type, opts);
+}
+
+static int unmount_fuse(const char *mnt, int quiet, int lazy)
+{
+	if (getuid() != 0) {
+		struct mntent *entp;
+		FILE *fp;
+		const char *user = NULL;
+		char uidstr[32];
+		unsigned uidlen = 0;
+		int found;
+		const char *mtab = _PATH_MOUNTED;
+
+		user = get_user_name();
+		if (user == NULL)
+			return -1;
+
+		fp = setmntent(mtab, "r");
+		if (fp == NULL) {
+			fprintf(stderr,
+				"%s: failed to open %s: %s\n", progname, mtab,
+				strerror(errno));
+			return -1;
+		}
+
+		uidlen = sprintf(uidstr, "%u", getuid());
+
+		found = 0;
+		while ((entp = getmntent(fp)) != NULL) {
+			if (!found && strcmp(entp->mnt_dir, mnt) == 0 &&
+			    (strcmp(entp->mnt_type, "fuse") == 0 ||
+			     strcmp(entp->mnt_type, "fuseblk") == 0 ||
+			     strncmp(entp->mnt_type, "fuse.", 5) == 0 ||
+			     strncmp(entp->mnt_type, "fuseblk.", 8) == 0)) {
+				char *p = strstr(entp->mnt_opts, "user=");
+				if (p &&
+				    (p == entp->mnt_opts || *(p-1) == ',') &&
+				    strcmp(p + 5, user) == 0) {
+					found = 1;
+					break;
+				}
+				/* /etc/mtab is a link pointing to
+				   /proc/mounts: */
+				else if ((p =
+					  strstr(entp->mnt_opts, "user_id=")) &&
+					 (p == entp->mnt_opts ||
+					  *(p-1) == ',') &&
+					 strncmp(p + 8, uidstr, uidlen) == 0 &&
+					 (*(p+8+uidlen) == ',' ||
+					  *(p+8+uidlen) == '\0')) {
+					found = 1;
+					break;
+				}
+			}
+		}
+		endmntent(fp);
+
+		if (!found) {
+			if (!quiet)
+				fprintf(stderr,
+					"%s: entry for %s not found in %s\n",
+					progname, mnt, mtab);
+			return -1;
+		}
+	}
+
+	return fuse_mnt_umount(progname, mnt, lazy);
+}
+
+static int count_fuse_fs(void)
+{
+	struct mntent *entp;
+	int count = 0;
+	const char *mtab = _PATH_MOUNTED;
+	FILE *fp = setmntent(mtab, "r");
+	if (fp == NULL) {
+		fprintf(stderr, "%s: failed to open %s: %s\n", progname, mtab,
+			strerror(errno));
+		return -1;
+	}
+	while ((entp = getmntent(fp)) != NULL) {
+		if (strcmp(entp->mnt_type, "fuse") == 0 ||
+		    strncmp(entp->mnt_type, "fuse.", 5) == 0)
+			count ++;
+	}
+	endmntent(fp);
+	return count;
+}
+
+
+#else /* IGNORE_MTAB */
+static int count_fuse_fs()
+{
+	return 0;
+}
+
+static int add_mount(const char *source, const char *mnt, const char *type,
+		     const char *opts)
+{
+	(void) source;
+	(void) mnt;
+	(void) type;
+	(void) opts;
+	return 0;
+}
+
+static int unmount_fuse(const char *mnt, int quiet, int lazy)
+{
+	return fuse_mnt_umount(progname, mnt, lazy);
+}
+#endif /* IGNORE_MTAB */
+
+static void strip_line(char *line)
+{
+	char *s = strchr(line, '#');
+	if (s != NULL)
+		s[0] = '\0';
+	for (s = line + strlen(line) - 1;
+	     s >= line && isspace((unsigned char) *s); s--);
+	s[1] = '\0';
+	for (s = line; isspace((unsigned char) *s); s++);
+	if (s != line)
+		memmove(line, s, strlen(s)+1);
+}
+
+static void parse_line(char *line, int linenum)
+{
+	int tmp;
+	if (strcmp(line, "user_allow_other") == 0)
+		user_allow_other = 1;
+	else if (sscanf(line, "mount_max = %i", &tmp) == 1)
+		mount_max = tmp;
+	else if(line[0])
+		fprintf(stderr,
+			"%s: unknown parameter in %s at line %i: '%s'\n",
+			progname, FUSE_CONF, linenum, line);
+}
+
+static void read_conf(void)
+{
+	FILE *fp = fopen(FUSE_CONF, "r");
+	if (fp != NULL) {
+		int linenum = 1;
+		char line[256];
+		int isnewline = 1;
+		while (fgets(line, sizeof(line), fp) != NULL) {
+			if (isnewline) {
+				if (line[strlen(line)-1] == '\n') {
+					strip_line(line);
+					parse_line(line, linenum);
+				} else {
+					isnewline = 0;
+				}
+			} else if(line[strlen(line)-1] == '\n') {
+				fprintf(stderr, "%s: reading %s: line %i too long\n", progname, FUSE_CONF, linenum);
+
+				isnewline = 1;
+			}
+			if (isnewline)
+				linenum ++;
+		}
+		if (!isnewline) {
+			fprintf(stderr, "%s: reading %s: missing newline at end of file\n", progname, FUSE_CONF);
+
+		}
+		fclose(fp);
+	} else if (errno != ENOENT) {
+		fprintf(stderr, "%s: failed to open %s: %s\n",
+			progname, FUSE_CONF, strerror(errno));
+	}
+}
+
+static int begins_with(const char *s, const char *beg)
+{
+	if (strncmp(s, beg, strlen(beg)) == 0)
+		return 1;
+	else
+		return 0;
+}
+
+struct mount_flags {
+	const char *opt;
+	unsigned long flag;
+	int on;
+	int safe;
+};
+
+static struct mount_flags mount_flags[] = {
+	{"rw",	    MS_RDONLY,	    0, 1},
+	{"ro",	    MS_RDONLY,	    1, 1},
+	{"suid",    MS_NOSUID,	    0, 0},
+	{"nosuid",  MS_NOSUID,	    1, 1},
+	{"dev",	    MS_NODEV,	    0, 0},
+	{"nodev",   MS_NODEV,	    1, 1},
+	{"exec",    MS_NOEXEC,	    0, 1},
+	{"noexec",  MS_NOEXEC,	    1, 1},
+	{"async",   MS_SYNCHRONOUS, 0, 1},
+	{"sync",    MS_SYNCHRONOUS, 1, 1},
+	{"atime",   MS_NOATIME,	    0, 1},
+	{"noatime", MS_NOATIME,	    1, 1},
+	{"dirsync", MS_DIRSYNC,	    1, 1},
+	{NULL,	    0,		    0, 0}
+};
+
+static int find_mount_flag(const char *s, unsigned len, int *on, int *flag)
+{
+	int i;
+
+	for (i = 0; mount_flags[i].opt != NULL; i++) {
+		const char *opt = mount_flags[i].opt;
+		if (strlen(opt) == len && strncmp(opt, s, len) == 0) {
+			*on = mount_flags[i].on;
+			*flag = mount_flags[i].flag;
+			if (!mount_flags[i].safe && getuid() != 0) {
+				*flag = 0;
+				fprintf(stderr,
+					"%s: unsafe option %s ignored\n",
+					progname, opt);
+			}
+			return 1;
+		}
+	}
+	return 0;
+}
+
+static int add_option(char **optsp, const char *opt, unsigned expand)
+{
+	char *newopts;
+	if (*optsp == NULL)
+		newopts = strdup(opt);
+	else {
+		unsigned oldsize = strlen(*optsp);
+		unsigned newsize = oldsize + 1 + strlen(opt) + expand + 1;
+		newopts = (char *) realloc(*optsp, newsize);
+		if (newopts)
+			sprintf(newopts + oldsize, ",%s", opt);
+	}
+	if (newopts == NULL) {
+		fprintf(stderr, "%s: failed to allocate memory\n", progname);
+		return -1;
+	}
+	*optsp = newopts;
+	return 0;
+}
+
+static int get_mnt_opts(int flags, char *opts, char **mnt_optsp)
+{
+	int i;
+	int l;
+
+	if (!(flags & MS_RDONLY) && add_option(mnt_optsp, "rw", 0) == -1)
+		return -1;
+
+	for (i = 0; mount_flags[i].opt != NULL; i++) {
+		if (mount_flags[i].on && (flags & mount_flags[i].flag) &&
+		    add_option(mnt_optsp, mount_flags[i].opt, 0) == -1)
+			return -1;
+	}
+
+	if (add_option(mnt_optsp, opts, 0) == -1)
+		return -1;
+	/* remove comma from end of opts*/
+	l = strlen(*mnt_optsp);
+	if ((*mnt_optsp)[l-1] == ',')
+		(*mnt_optsp)[l-1] = '\0';
+	if (getuid() != 0) {
+		const char *user = get_user_name();
+		if (user == NULL)
+			return -1;
+
+		if (add_option(mnt_optsp, "user=", strlen(user)) == -1)
+			return -1;
+		strcat(*mnt_optsp, user);
+	}
+	return 0;
+}
+
+static int opt_eq(const char *s, unsigned len, const char *opt)
+{
+	if(strlen(opt) == len && strncmp(s, opt, len) == 0)
+		return 1;
+	else
+		return 0;
+}
+
+static int get_string_opt(const char *s, unsigned len, const char *opt,
+			  char **val)
+{
+	unsigned opt_len = strlen(opt);
+
+	if (*val)
+		free(*val);
+	*val = (char *) malloc(len - opt_len + 1);
+	if (!*val) {
+		fprintf(stderr, "%s: failed to allocate memory\n", progname);
+		return 0;
+	}
+
+	memcpy(*val, s + opt_len, len - opt_len);
+	(*val)[len - opt_len] = '\0';
+	return 1;
+}
+
+static int do_mount(const char *mnt, char **typep, mode_t rootmode,
+		    int fd, const char *opts, const char *dev, char **sourcep,
+		    char **mnt_optsp, off_t rootsize)
+{
+	int res;
+	int flags = MS_NOSUID | MS_NODEV;
+	char *optbuf;
+	char *mnt_opts = NULL;
+	const char *s;
+	char *d;
+	char *fsname = NULL;
+	char *subtype = NULL;
+	char *source = NULL;
+	char *type = NULL;
+	int check_empty = 1;
+	int blkdev = 0;
+
+	optbuf = (char *) malloc(strlen(opts) + 128);
+	if (!optbuf) {
+		fprintf(stderr, "%s: failed to allocate memory\n", progname);
+		return -1;
+	}
+
+	for (s = opts, d = optbuf; *s;) {
+		unsigned len;
+		const char *fsname_str = "fsname=";
+		const char *subtype_str = "subtype=";
+		for (len = 0; s[len] && s[len] != ','; len++);
+		if (begins_with(s, fsname_str)) {
+			if (!get_string_opt(s, len, fsname_str, &fsname))
+				goto err;
+		} else if (begins_with(s, subtype_str)) {
+			if (!get_string_opt(s, len, subtype_str, &subtype))
+				goto err;
+		} else if (opt_eq(s, len, "blkdev")) {
+			if (getuid() != 0) {
+				fprintf(stderr,
+					"%s: option blkdev is privileged\n",
+					progname);
+				goto err;
+			}
+			blkdev = 1;
+		} else if (opt_eq(s, len, "nonempty")) {
+			check_empty = 0;
+		} else if (!begins_with(s, "fd=") &&
+			   !begins_with(s, "rootmode=") &&
+			   !begins_with(s, "user_id=") &&
+			   !begins_with(s, "group_id=")) {
+			int on;
+			int flag;
+			int skip_option = 0;
+			if (opt_eq(s, len, "large_read")) {
+				struct utsname utsname;
+				unsigned kmaj, kmin;
+				res = uname(&utsname);
+				if (res == 0 &&
+				    sscanf(utsname.release, "%u.%u",
+					   &kmaj, &kmin) == 2 &&
+				    (kmaj > 2 || (kmaj == 2 && kmin > 4))) {
+					fprintf(stderr, "%s: note: 'large_read' mount option is deprecated for %i.%i kernels\n", progname, kmaj, kmin);
+					skip_option = 1;
+				}
+			}
+			if (getuid() != 0 && !user_allow_other &&
+			    (opt_eq(s, len, "allow_other") ||
+			     opt_eq(s, len, "allow_root"))) {
+				fprintf(stderr, "%s: option %.*s only allowed if 'user_allow_other' is set in /etc/fuse.conf\n", progname, len, s);
+				goto err;
+			}
+			if (!skip_option) {
+				if (find_mount_flag(s, len, &on, &flag)) {
+					if (on)
+						flags |= flag;
+					else
+						flags  &= ~flag;
+				} else {
+					memcpy(d, s, len);
+					d += len;
+					*d++ = ',';
+				}
+			}
+		}
+		s += len;
+		if (*s)
+			s++;
+	}
+	*d = '\0';
+	res = get_mnt_opts(flags, optbuf, &mnt_opts);
+	if (res == -1)
+		goto err;
+
+	sprintf(d, "fd=%i,rootmode=%o,user_id=%i,group_id=%i",
+		fd, rootmode, getuid(), getgid());
+
+	if (check_empty &&
+	    fuse_mnt_check_empty(progname, mnt, rootmode, rootsize) == -1)
+		goto err;
+
+	source = malloc((fsname ? strlen(fsname) : 0) +
+			(subtype ? strlen(subtype) : 0) + strlen(dev) + 32);
+
+	type = malloc((subtype ? strlen(subtype) : 0) + 32);
+	if (!type || !source) {
+		fprintf(stderr, "%s: failed to allocate memory\n", progname);
+		goto err;
+	}
+
+	if (subtype)
+		sprintf(type, "%s.%s", blkdev ? "fuseblk" : "fuse", subtype);
+	else
+		strcpy(type, blkdev ? "fuseblk" : "fuse");
+
+	if (fsname)
+		strcpy(source, fsname);
+	else
+		strcpy(source, subtype ? subtype : dev);
+
+	res = mount(source, mnt, type, flags, optbuf);
+	if (res == -1 && errno == ENODEV && subtype) {
+		/* Probably missing subtype support */
+		strcpy(type, blkdev ? "fuseblk" : "fuse");
+		if (fsname) {
+			if (!blkdev)
+				sprintf(source, "%s#%s", subtype, fsname);
+		} else {
+			strcpy(source, type);
+		}
+
+		res = mount(source, mnt, type, flags, optbuf);
+	}
+	if (res == -1 && errno == EINVAL) {
+		/* It could be an old version not supporting group_id */
+		sprintf(d, "fd=%i,rootmode=%o,user_id=%i",
+			fd, rootmode, getuid());
+		res = mount(source, mnt, type, flags, optbuf);
+	}
+	if (res == -1) {
+		int errno_save = errno;
+		if (blkdev && errno == ENODEV && !fuse_mnt_check_fuseblk())
+			fprintf(stderr, "%s: 'fuseblk' support missing\n",
+				progname);
+		else
+			fprintf(stderr, "%s: mount failed: %s\n", progname,
+				strerror(errno_save));
+		goto err;
+	} else {
+		*sourcep = source;
+		*typep = type;
+		*mnt_optsp = mnt_opts;
+	}
+	free(fsname);
+	free(optbuf);
+
+	return res;
+
+err:
+	free(fsname);
+	free(subtype);
+	free(source);
+	free(type);
+	free(mnt_opts);
+	free(optbuf);
+	return -1;
+}
+
+static int check_version(const char *dev)
+{
+	int res;
+	int majorver;
+	int minorver;
+	const char *version_file;
+	FILE *vf;
+
+	if (strcmp(dev, FUSE_DEV_OLD) != 0)
+		return 0;
+
+	version_file = FUSE_VERSION_FILE_OLD;
+	vf = fopen(version_file, "r");
+	if (vf == NULL) {
+		fprintf(stderr, "%s: kernel interface too old\n", progname);
+		return -1;
+	}
+	res = fscanf(vf, "%i.%i", &majorver, &minorver);
+	fclose(vf);
+	if (res != 2) {
+		fprintf(stderr, "%s: error reading %s\n", progname,
+			version_file);
+		return -1;
+	}
+	if (majorver < 3) {
+		fprintf(stderr, "%s: kernel interface too old\n", progname);
+		return -1;
+	}
+	return 0;
+}
+
+static int check_perm(const char **mntp, struct stat *stbuf, int *currdir_fd,
+		      int *mountpoint_fd)
+{
+	int res;
+	const char *mnt = *mntp;
+	const char *origmnt = mnt;
+
+	res = lstat(mnt, stbuf);
+	if (res == -1) {
+		fprintf(stderr, "%s: failed to access mountpoint %s: %s\n",
+			progname, mnt, strerror(errno));
+		return -1;
+	}
+
+	/* No permission checking is done for root */
+	if (getuid() == 0)
+		return 0;
+
+	if (S_ISDIR(stbuf->st_mode)) {
+		*currdir_fd = open(".", O_RDONLY);
+		if (*currdir_fd == -1) {
+			fprintf(stderr,
+				"%s: failed to open current directory: %s\n",
+				progname, strerror(errno));
+			return -1;
+		}
+		res = chdir(mnt);
+		if (res == -1) {
+			fprintf(stderr,
+				"%s: failed to chdir to mountpoint: %s\n",
+				progname, strerror(errno));
+			return -1;
+		}
+		mnt = *mntp = ".";
+		res = lstat(mnt, stbuf);
+		if (res == -1) {
+			fprintf(stderr,
+				"%s: failed to access mountpoint %s: %s\n",
+				progname, origmnt, strerror(errno));
+			return -1;
+		}
+
+		if ((stbuf->st_mode & S_ISVTX) && stbuf->st_uid != getuid()) {
+			fprintf(stderr, "%s: mountpoint %s not owned by user\n",
+				progname, origmnt);
+			return -1;
+		}
+
+		res = access(mnt, W_OK);
+		if (res == -1) {
+			fprintf(stderr, "%s: user has no write access to mountpoint %s\n",
+				progname, origmnt);
+			return -1;
+		}
+	} else if (S_ISREG(stbuf->st_mode)) {
+		static char procfile[256];
+		*mountpoint_fd = open(mnt, O_WRONLY);
+		if (*mountpoint_fd == -1) {
+			fprintf(stderr, "%s: failed to open %s: %s\n",
+				progname, mnt, strerror(errno));
+			return -1;
+		}
+		res = fstat(*mountpoint_fd, stbuf);
+		if (res == -1) {
+			fprintf(stderr,
+				"%s: failed to access mountpoint %s: %s\n",
+				progname, mnt, strerror(errno));
+			return -1;
+		}
+		if (!S_ISREG(stbuf->st_mode)) {
+			fprintf(stderr,
+				"%s: mountpoint %s is no longer a regular file\n",
+				progname, mnt);
+			return -1;
+		}
+
+		sprintf(procfile, "/proc/self/fd/%i", *mountpoint_fd);
+		*mntp = procfile;
+	} else {
+		fprintf(stderr,
+			"%s: mountpoint %s is not a directory or a regular file\n",
+			progname, mnt);
+		return -1;
+	}
+
+
+	return 0;
+}
+
+static int try_open(const char *dev, char **devp, int silent)
+{
+	int fd = open(dev, O_RDWR);
+	if (fd != -1) {
+		*devp = strdup(dev);
+		if (*devp == NULL) {
+			fprintf(stderr, "%s: failed to allocate memory\n",
+				progname);
+			close(fd);
+			fd = -1;
+		}
+	} else if (errno == ENODEV ||
+		   errno == ENOENT)/* check for ENOENT too, for the udev case */
+		return -2;
+	else if (!silent) {
+		fprintf(stderr, "%s: failed to open %s: %s\n", progname, dev,
+			strerror(errno));
+	}
+	return fd;
+}
+
+static int try_open_fuse_device(char **devp)
+{
+	int fd;
+	int err;
+
+	drop_privs();
+	fd = try_open(FUSE_DEV_NEW, devp, 0);
+	restore_privs();
+	if (fd >= 0)
+		return fd;
+
+	err = fd;
+	fd = try_open(FUSE_DEV_OLD, devp, 1);
+	if (fd >= 0)
+		return fd;
+
+	return err;
+}
+
+static int open_fuse_device(char **devp)
+{
+	int fd = try_open_fuse_device(devp);
+	if (fd >= -1)
+		return fd;
+
+	fprintf(stderr,
+		"%s: fuse device not found, try 'modprobe fuse' first\n",
+		progname);
+
+	return -1;
+}
+
+
+static int mount_fuse(const char *mnt, const char *opts)
+{
+	int res;
+	int fd;
+	char *dev;
+	struct stat stbuf;
+	char *type = NULL;
+	char *source = NULL;
+	char *mnt_opts = NULL;
+	const char *real_mnt = mnt;
+	int currdir_fd = -1;
+	int mountpoint_fd = -1;
+
+	fd = open_fuse_device(&dev);
+	if (fd == -1)
+		return -1;
+
+	drop_privs();
+	read_conf();
+
+	if (getuid() != 0 && mount_max != -1) {
+		int mount_count = count_fuse_fs();
+		if (mount_count >= mount_max) {
+			fprintf(stderr, "%s: too many FUSE filesystems mounted; mount_max=N can be set in /etc/fuse.conf\n", progname);
+			close(fd);
+			return -1;
+		}
+	}
+
+	res = check_version(dev);
+	if (res != -1) {
+		res = check_perm(&real_mnt, &stbuf, &currdir_fd,
+				 &mountpoint_fd);
+		restore_privs();
+		if (res != -1)
+			res = do_mount(real_mnt, &type, stbuf.st_mode & S_IFMT,
+				       fd, opts, dev, &source, &mnt_opts,
+				       stbuf.st_size);
+	} else
+		restore_privs();
+
+	if (currdir_fd != -1) {
+		fchdir(currdir_fd);
+		close(currdir_fd);
+	}
+	if (mountpoint_fd != -1)
+		close(mountpoint_fd);
+
+	if (res == -1) {
+		close(fd);
+		return -1;
+	}
+
+	if (geteuid() == 0) {
+		res = add_mount(source, mnt, type, mnt_opts);
+		if (res == -1) {
+			umount2(mnt, 2); /* lazy umount */
+			close(fd);
+			return -1;
+		}
+	}
+
+	free(source);
+	free(type);
+	free(mnt_opts);
+	free(dev);
+
+	return fd;
+}
+
+static int send_fd(int sock_fd, int fd)
+{
+	int retval;
+	struct msghdr msg;
+	struct cmsghdr *p_cmsg;
+	struct iovec vec;
+	size_t cmsgbuf[CMSG_SPACE(sizeof(fd)) / sizeof(size_t)];
+	int *p_fds;
+	char sendchar = 0;
+
+	msg.msg_control = cmsgbuf;
+	msg.msg_controllen = sizeof(cmsgbuf);
+	p_cmsg = CMSG_FIRSTHDR(&msg);
+	p_cmsg->cmsg_level = SOL_SOCKET;
+	p_cmsg->cmsg_type = SCM_RIGHTS;
+	p_cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
+	p_fds = (int *) CMSG_DATA(p_cmsg);
+	*p_fds = fd;
+	msg.msg_controllen = p_cmsg->cmsg_len;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_iov = &vec;
+	msg.msg_iovlen = 1;
+	msg.msg_flags = 0;
+	/* "To pass file descriptors or credentials you need to send/read at
+	 * least one byte" (man 7 unix) */
+	vec.iov_base = &sendchar;
+	vec.iov_len = sizeof(sendchar);
+	while ((retval = sendmsg(sock_fd, &msg, 0)) == -1 && errno == EINTR);
+	if (retval != 1) {
+		perror("sending file descriptor");
+		return -1;
+	}
+	return 0;
+}
+
+static void usage(void)
+{
+	fprintf(stderr,
+		"%s: [options] mountpoint\n"
+		"Options:\n"
+		" -h		    print help\n"
+		" -V		    print version\n"
+		" -o opt[,opt...]   mount options\n"
+		" -u		    unmount\n"
+		" -q		    quiet\n"
+		" -z		    lazy unmount\n",
+		progname);
+	exit(1);
+}
+
+static void show_version(void)
+{
+	printf("fusermount version: %s\n", PACKAGE_VERSION);
+	exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+	int ch;
+	int fd;
+	int res;
+	char *origmnt;
+	char *mnt;
+	static int unmount = 0;
+	static int lazy = 0;
+	static int quiet = 0;
+	char *commfd;
+	int cfd;
+	const char *opts = "";
+
+	static const struct option long_opts[] = {
+		{"unmount", no_argument, NULL, 'u'},
+		{"lazy",    no_argument, NULL, 'z'},
+		{"quiet",   no_argument, NULL, 'q'},
+		{"help",    no_argument, NULL, 'h'},
+		{"version", no_argument, NULL, 'V'},
+		{0, 0, 0, 0}};
+
+	progname = strdup(argv[0]);
+	if (progname == NULL) {
+		fprintf(stderr, "%s: failed to allocate memory\n", argv[0]);
+		exit(1);
+	}
+
+	while ((ch = getopt_long(argc, argv, "hVo:uzq", long_opts,
+				 NULL)) != -1) {
+		switch (ch) {
+		case 'h':
+			usage();
+			break;
+
+		case 'V':
+			show_version();
+			break;
+
+		case 'o':
+			opts = optarg;
+			break;
+
+		case 'u':
+			unmount = 1;
+			break;
+
+		case 'z':
+			lazy = 1;
+			break;
+
+		case 'q':
+			quiet = 1;
+			break;
+
+		default:
+			exit(1);
+		}
+	}
+
+	if (lazy && !unmount) {
+		fprintf(stderr, "%s: -z can only be used with -u\n", progname);
+		exit(1);
+	}
+
+	if (optind >= argc) {
+		fprintf(stderr, "%s: missing mountpoint argument\n", progname);
+		exit(1);
+	} else if (argc > optind + 1) {
+		fprintf(stderr, "%s: extra arguments after the mountpoint\n",
+			progname);
+		exit(1);
+	}
+
+	origmnt = argv[optind];
+
+	drop_privs();
+	mnt = fuse_mnt_resolve_path(progname, origmnt);
+	restore_privs();
+	if (mnt == NULL)
+		exit(1);
+
+	umask(033);
+	if (unmount) {
+		if (geteuid() == 0)
+			res = unmount_fuse(mnt, quiet, lazy);
+		else {
+			res = umount2(mnt, lazy ? 2 : 0);
+			if (res == -1 && !quiet)
+				fprintf(stderr,
+					"%s: failed to unmount %s: %s\n",
+					progname, mnt, strerror(errno));
+		}
+		if (res == -1)
+			exit(1);
+		return 0;
+	}
+
+	commfd = getenv(FUSE_COMMFD_ENV);
+	if (commfd == NULL) {
+		fprintf(stderr, "%s: old style mounting not supported\n",
+			progname);
+		exit(1);
+	}
+
+	fd = mount_fuse(mnt, opts);
+	if (fd == -1)
+		exit(1);
+
+	cfd = atoi(commfd);
+	res = send_fd(cfd, fd);
+	if (res == -1)
+		exit(1);
+
+	return 0;
+}