path: root/lib/mount.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>

  Architecture specific file system mounting (Linux).

  This program can be distributed under the terms of the GNU LGPLv2.
  See the file COPYING.LIB.
*/

/* For environ */
#define _GNU_SOURCE

#include "fuse_config.h"
#include "fuse_i.h"
#include "fuse_misc.h"
#include "fuse_opt.h"
#include "mount_util.h"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stddef.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <poll.h>
#include <spawn.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <ctype.h>

#include "fuse_mount_compat.h"

#ifdef __NetBSD__
#include <perfuse.h>

#define MS_RDONLY	MNT_RDONLY
#define MS_NOSUID	MNT_NOSUID
#define MS_NODEV	MNT_NODEV
#define MS_NOEXEC	MNT_NOEXEC
#define MS_SYNCHRONOUS	MNT_SYNCHRONOUS
#define MS_NOATIME	MNT_NOATIME
#define MS_NOSYMFOLLOW	MNT_NOSYMFOLLOW

#define umount2(mnt, flags) unmount(mnt, (flags == 2) ? MNT_FORCE : 0)
#endif

#define FUSERMOUNT_PROG		"fusermount3"
#define FUSE_COMMFD_ENV		"_FUSE_COMMFD"
#define FUSE_COMMFD2_ENV	"_FUSE_COMMFD2"

#ifndef MS_DIRSYNC
#define MS_DIRSYNC 128
#endif

/* === new-mount-API helpers (Linux only) ================================= */
#if defined(__linux__)
#include <linux/mount.h>
#include <sys/syscall.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

/* Fallback-Defines, falls ältere Kernel-Header verwendet werden */
#ifndef FSCONFIG_SET_FLAG
# define FSCONFIG_SET_FLAG     0
# define FSCONFIG_SET_STRING   1
# define FSCONFIG_SET_BINARY   2
# define FSCONFIG_SET_PATH     3
# define FSCONFIG_SET_PATH_EMPTY 4
# define FSCONFIG_SET_FD       5
# define FSCONFIG_CMD_CREATE   6
# define FSCONFIG_CMD_RECONFIGURE 7
#endif
#ifndef MOVE_MOUNT_F_EMPTY_PATH
# define MOVE_MOUNT_F_EMPTY_PATH 0x00000004
#endif

/* Syscall-Nummern fallbacken, wenn libc sie nicht kennt */
#ifndef SYS_fsopen
#  if defined(__x86_64__)
#    define SYS_fsopen 430
#  elif defined(__aarch64__)
#    define SYS_fsopen 434
#  endif
#endif
#ifndef SYS_fsconfig
#  if defined(__x86_64__)
#    define SYS_fsconfig 431
#  elif defined(__aarch64__)
#    define SYS_fsconfig 435
#  endif
#endif
#ifndef SYS_fsmount
#  if defined(__x86_64__)
#    define SYS_fsmount 432
#  elif defined(__aarch64__)
#    define SYS_fsmount 436
#  endif
#endif
#ifndef SYS_move_mount
#  if defined(__x86_64__)
#    define SYS_move_mount 429
#  elif defined(__aarch64__)
#    define SYS_move_mount 433
#  endif
#endif

static inline int x_fsopen(const char *fsname, unsigned int flags) {
    errno = 0; return (int)syscall(SYS_fsopen, fsname, flags);
}
static inline int x_fsconfig(int fd, unsigned int cmd,
                             const char *key, const void *val, int aux) {
    errno = 0; return (int)syscall(SYS_fsconfig, fd, cmd, key, val, aux);
}
static inline int x_fsmount(int fsfd, unsigned int flags, unsigned int ms_flags) {
    errno = 0; return (int)syscall(SYS_fsmount, fsfd, flags, ms_flags);
}
static inline int x_move_mount(int from_dfd, const char *from_pathname,
                               int to_dfd, const char *to_pathname,
                               unsigned int flags) {
    errno = 0; return (int)syscall(SYS_move_mount, from_dfd, from_pathname, to_dfd, to_pathname, flags);
}

/* robustes Splitten der -o Kette:
   - Respektiert Backslashes und '"/" Quotes
   - Ruft cb(key, value|NULL) pro Teiloption auf (value==NULL => reines Flag) */
struct opt_cb {
    int (*cb)(const char *key, const char *val, void *userdata);
    void *userdata;
};
static void for_each_o_subopt(const char *oarg, struct opt_cb *h) {
    const char *p = oarg, *start = oarg;
    bool esc = false, in_sq = false, in_dq = false;

    for (; *p; ++p) {
        if (esc) { esc = false; continue; }
        if (*p == '\\') { esc = true; continue; }
        if (*p == '\'' && !in_dq) { in_sq = !in_sq; continue; }
        if (*p == '\"' && !in_sq) { in_dq = !in_dq; continue; }
        if (*p == ',' && !in_sq && !in_dq) {
            size_t len = (size_t)(p - start);
            if (len) {
                char *tmp = (char*)malloc(len + 1);
                memcpy(tmp, start, len);
                tmp[len] = '\0';
                char *eq = strchr(tmp, '=');
                if (eq) { *eq = '\0'; h->cb(tmp, eq + 1, h->userdata); }
                else    { h->cb(tmp, NULL,     h->userdata); }
                free(tmp);
            }
            start = p + 1;
        }
    }
    if (p > start) {
        size_t len = (size_t)(p - start);
        char *tmp = (char*)malloc(len + 1);
        memcpy(tmp, start, len);
        tmp[len] = '\0';
        char *eq = strchr(tmp, '=');
        if (eq) { *eq = '\0'; h->cb(tmp, eq + 1, h->userdata); }
        else    { h->cb(tmp, NULL,     h->userdata); }
        free(tmp);
    }
}

/* Sammelstruktur für Pflicht-Keys */
struct fuse_kv_acc {
    int fd; bool have_fd;
};
static int collect_core_opts_cb(const char *key, const char *val, void *userdata) {
    struct fuse_kv_acc *acc = (struct fuse_kv_acc*)userdata;
    if (!key) return 0;
    if (strcmp(key, "fd") == 0 && val) {
        acc->fd = atoi(val);
        acc->have_fd = true;
    }
    return 0;
}

static const char *extract_subtype(const char *type) {
    if (!type) return NULL;
    const char *dot = strchr(type, '.');
    return dot ? dot + 1 : NULL;
}

/* C-kompatibler Callback: setzt einen Key/Value mit fsconfig.
   Überspringt "fd", weil der separat als FSCONFIG_SET_FD gesetzt wird. */
static int fsconfig_apply_cb(const char *key, const char *val, void *userdata)
{
    int fsfd_local = *(int *)userdata;

    if (!key) return 0;
    if (strcmp(key, "fd") == 0) return 0; /* schon separat gesetzt */

    int rc;
    if (val && *val) {
        rc = x_fsconfig(fsfd_local, FSCONFIG_SET_STRING, key, val, 0);
    } else {
        rc = x_fsconfig(fsfd_local, FSCONFIG_SET_FLAG, key, NULL, 0);
    }
    return (rc < 0) ? -1 : 0;
}

/* Übergibt ALLE Optionen einzeln (inkl. context=… mit Kommata) via fsconfig */
static int set_all_opts_via_fsconfig(int fsfd, const char *optstr)
{
    if (!optstr || !*optstr)
        return 0;

    /* eigener robuster Parser (wie oben), der Kommas in Quotes/mit Backslash respektiert */
    const char *s = optstr;
    const char *p = s, *start = s;
    bool esc = false, in_sq = false, in_dq = false;

    for (; *p; ++p) {
        if (esc) { esc = false; continue; }
        if (*p == '\\') { esc = true; continue; }
        if (*p == '\'' && !in_dq) { in_sq = !in_sq; continue; }
        if (*p == '\"' && !in_sq) { in_dq = !in_dq; continue; }

        if (*p == ',' && !in_sq && !in_dq) {
            size_t len = (size_t)(p - start);
            if (len) {
                char *tmp = (char*)malloc(len + 1);
                if (!tmp) { errno = ENOMEM; return -1; }
                memcpy(tmp, start, len);
                tmp[len] = '\0';

                char *eq = strchr(tmp, '=');
                int rc;
                if (eq) {
                    *eq = '\0';
                    rc = fsconfig_apply_cb(tmp, eq + 1, &fsfd);
                } else {
                    rc = fsconfig_apply_cb(tmp, NULL, &fsfd);
                }
                free(tmp);
                if (rc < 0) return -1;
            }
            start = p + 1;
        }
    }

    /* letztes Segment */
    if (p > start) {
        size_t len = (size_t)(p - start);
        char *tmp = (char*)malloc(len + 1);
        if (!tmp) { errno = ENOMEM; return -1; }
        memcpy(tmp, start, len);
        tmp[len] = '\0';

        char *eq = strchr(tmp, '=');
        int rc;
        if (eq) {
            *eq = '\0';
            rc = fsconfig_apply_cb(tmp, eq + 1, &fsfd);
        } else {
            rc = fsconfig_apply_cb(tmp, NULL, &fsfd);
        }
        free(tmp);
        if (rc < 0) return -1;
    }

    return 0;
}

/* Hauptfunktion: versucht neue Mount-API; bei Erfolg 0, sonst -1 für Fallback */
static int fuse_mount_with_fsopen_try(const char *type,
                                      const char *mountpoint,
                                      const char *optstr,
                                      unsigned long ms_flags)
{
    int fsfd = x_fsopen(type && strncmp(type, "fuseblk", 7)==0 ? "fuseblk" : "fuse", 0);
    if (fsfd < 0) {
        if (errno == ENOSYS) return -1; /* Kernel kann es nicht */
        return -1;
    }

    /* Pflicht: fd aus optstr ziehen */
    struct fuse_kv_acc acc = { .fd = -1, .have_fd = false };
    if (optstr && *optstr) {
        struct opt_cb c = { .cb = collect_core_opts_cb, .userdata = &acc };
        for_each_o_subopt(optstr, &c);
    }
    if (!acc.have_fd) { close(fsfd); errno = EINVAL; return -1; }

    /* subtype setzen (falls "fuse.xxx") */
    const char *sub = extract_subtype(type);
    if (sub && *sub) {
        if (x_fsconfig(fsfd, FSCONFIG_SET_STRING, "subtype", sub, 0) < 0) {
            int saved = errno; close(fsfd); errno = saved; return -1;
        }
    }

    /* fd reinreichen */
    if (x_fsconfig(fsfd, FSCONFIG_SET_FD, "fd", NULL, acc.fd) < 0) {
        int saved = errno; close(fsfd); errno = saved; return -1;
    }

    /* nun alle restlichen Optionen einzeln setzen (inkl. context=… mit Kommata) */
    if (set_all_opts_via_fsconfig(fsfd, optstr) < 0) {
        int saved = errno; close(fsfd); errno = saved; return -1;
    }

    if (x_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) < 0) {
        int saved = errno; close(fsfd); errno = saved; return -1;
    }

    int mfd = x_fsmount(fsfd, 0, (unsigned int)ms_flags);
    if (mfd < 0) {
        int saved = errno; close(fsfd); errno = saved; return -1;
    }

    if (x_move_mount(mfd, "", AT_FDCWD, mountpoint, MOVE_MOUNT_F_EMPTY_PATH) < 0) {
        int saved = errno; close(mfd); close(fsfd); errno = saved; return -1;
    }

    close(mfd);
    close(fsfd);
    return 0;
}
#endif /* __linux__ */
/* === end new-mount-API helpers ========================================= */

enum {
	KEY_KERN_FLAG,
	KEY_KERN_OPT,
	KEY_FUSERMOUNT_OPT,
	KEY_SUBTYPE_OPT,
	KEY_MTAB_OPT,
	KEY_ALLOW_OTHER,
	KEY_RO,
};

struct mount_opts {
	int allow_other;
	int flags;
	int auto_unmount;
	int blkdev;
	char *fsname;
	char *subtype;
	char *subtype_opt;
	char *mtab_opts;
	char *fusermount_opts;
	char *kernel_opts;
	unsigned max_read;
};

#define FUSE_MOUNT_OPT(t, p) { t, offsetof(struct mount_opts, p), 1 }

static const struct fuse_opt fuse_mount_opts[] = {
	FUSE_MOUNT_OPT("allow_other",		allow_other),
	FUSE_MOUNT_OPT("blkdev",		blkdev),
	FUSE_MOUNT_OPT("auto_unmount",		auto_unmount),
	FUSE_MOUNT_OPT("fsname=%s",		fsname),
	FUSE_MOUNT_OPT("max_read=%u",		max_read),
	FUSE_MOUNT_OPT("subtype=%s",		subtype),
	FUSE_OPT_KEY("allow_other",		KEY_KERN_OPT),
	FUSE_OPT_KEY("auto_unmount",		KEY_FUSERMOUNT_OPT),
	FUSE_OPT_KEY("blkdev",			KEY_FUSERMOUNT_OPT),
	FUSE_OPT_KEY("fsname=",			KEY_FUSERMOUNT_OPT),
	FUSE_OPT_KEY("subtype=",		KEY_SUBTYPE_OPT),
	FUSE_OPT_KEY("blksize=",		KEY_KERN_OPT),
	FUSE_OPT_KEY("default_permissions",	KEY_KERN_OPT),
	FUSE_OPT_KEY("context=",		KEY_KERN_OPT),
	FUSE_OPT_KEY("fscontext=",		KEY_KERN_OPT),
	FUSE_OPT_KEY("defcontext=",		KEY_KERN_OPT),
	FUSE_OPT_KEY("rootcontext=",		KEY_KERN_OPT),
	FUSE_OPT_KEY("max_read=",		KEY_KERN_OPT),
	FUSE_OPT_KEY("user=",			KEY_MTAB_OPT),
	FUSE_OPT_KEY("-n",			KEY_MTAB_OPT),
	FUSE_OPT_KEY("-r",			KEY_RO),
	FUSE_OPT_KEY("ro",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("rw",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("suid",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("nosuid",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("dev",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("nodev",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("exec",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("noexec",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("async",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("sync",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("dirsync",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("noatime",			KEY_KERN_FLAG),
	FUSE_OPT_KEY("nodiratime",		KEY_KERN_FLAG),
	FUSE_OPT_KEY("nostrictatime",		KEY_KERN_FLAG),
	FUSE_OPT_KEY("symfollow",		KEY_KERN_FLAG),
	FUSE_OPT_KEY("nosymfollow",		KEY_KERN_FLAG),
	FUSE_OPT_END
};

/*
 * Running fusermount by calling 'posix_spawn'
 *
 * @param out_pid might be NULL
 */
static int fusermount_posix_spawn(posix_spawn_file_actions_t *action,
				  char const * const argv[], pid_t *out_pid)
{
	const char *full_path = FUSERMOUNT_DIR "/" FUSERMOUNT_PROG;
	pid_t pid;

	/* See man 7 environ for the global environ pointer */

	/* first try the install path */
	int status = posix_spawn(&pid, full_path,  action, NULL,
				 (char * const *) argv, environ);
	if (status != 0) {
		/* if that fails, try a system install */
		status = posix_spawnp(&pid, FUSERMOUNT_PROG, action, NULL,
				      (char * const *) argv, environ);
	}

	if (status != 0) {
		fuse_log(FUSE_LOG_ERR,
			 "On calling fusermount posix_spawn failed: %s\n",
			 strerror(status));
		return -status;
	}

	if (out_pid)
		*out_pid = pid;
	else
		waitpid(pid, NULL, 0); /* FIXME: check exit code and return error if any */

	return 0;
}

void fuse_mount_version(void)
{
	char const *const argv[] = {FUSERMOUNT_PROG, "--version", NULL};
	int status = fusermount_posix_spawn(NULL, argv, NULL);

	if(status != 0)
		fuse_log(FUSE_LOG_ERR, "Running '%s --version' failed",
			 FUSERMOUNT_PROG);
}

struct mount_flags {
	const char *opt;
	unsigned long flag;
	int on;
};

static const struct mount_flags mount_flags[] = {
	{"rw",	    MS_RDONLY,	    0},
	{"ro",	    MS_RDONLY,	    1},
	{"suid",    MS_NOSUID,	    0},
	{"nosuid",  MS_NOSUID,	    1},
	{"dev",	    MS_NODEV,	    0},
	{"nodev",   MS_NODEV,	    1},
	{"exec",    MS_NOEXEC,	    0},
	{"noexec",  MS_NOEXEC,	    1},
	{"async",   MS_SYNCHRONOUS, 0},
	{"sync",    MS_SYNCHRONOUS, 1},
	{"noatime", MS_NOATIME,	    1},
	{"nodiratime",	    MS_NODIRATIME,	1},
	{"norelatime",	    MS_RELATIME,	0},
	{"nostrictatime",   MS_STRICTATIME,	0},
	{"symfollow",	    MS_NOSYMFOLLOW,	0},
	{"nosymfollow",	    MS_NOSYMFOLLOW,	1},
#ifndef __NetBSD__
	{"dirsync", MS_DIRSYNC,	    1},
#endif
	{NULL,	    0,		    0}
};

unsigned get_max_read(struct mount_opts *o)
{
	return o->max_read;
}

static void set_mount_flag(const char *s, int *flags)
{
	int i;

	for (i = 0; mount_flags[i].opt != NULL; i++) {
		const char *opt = mount_flags[i].opt;
		if (strcmp(opt, s) == 0) {
			if (mount_flags[i].on)
				*flags |= mount_flags[i].flag;
			else
				*flags &= ~mount_flags[i].flag;
			return;
		}
	}
	fuse_log(FUSE_LOG_ERR, "fuse: internal error, can't find mount flag\n");
	abort();
}

static int fuse_mount_opt_proc(void *data, const char *arg, int key,
			       struct fuse_args *outargs)
{
	(void) outargs;
	struct mount_opts *mo = data;

	switch (key) {
	case KEY_RO:
		arg = "ro";
		/* fall through */
	case KEY_KERN_FLAG:
		set_mount_flag(arg, &mo->flags);
		return 0;

	case KEY_KERN_OPT:
		return fuse_opt_add_opt(&mo->kernel_opts, arg);

	case KEY_FUSERMOUNT_OPT:
		return fuse_opt_add_opt_escaped(&mo->fusermount_opts, arg);

	case KEY_SUBTYPE_OPT:
		return fuse_opt_add_opt(&mo->subtype_opt, arg);

	case KEY_MTAB_OPT:
		return fuse_opt_add_opt(&mo->mtab_opts, arg);

	/* Third party options like 'x-gvfs-notrash' */
	case FUSE_OPT_KEY_OPT:
		return (strncmp("x-", arg, 2) == 0) ?
			fuse_opt_add_opt(&mo->mtab_opts, arg) :
			1;
	}

	/* Pass through unknown options */
	return 1;
}

/* return value:
 * >= 0	 => fd
 * -1	 => error
 */
static int receive_fd(int fd)
{
	struct msghdr msg;
	struct iovec iov;
	char buf[1];
	int rv;
	size_t ccmsg[CMSG_SPACE(sizeof(int)) / sizeof(size_t)];
	struct cmsghdr *cmsg;

	iov.iov_base = buf;
	iov.iov_len = 1;

	memset(&msg, 0, sizeof(msg));
	msg.msg_name = 0;
	msg.msg_namelen = 0;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	/* old BSD implementations should use msg_accrights instead of
	 * msg_control; the interface is different. */
	msg.msg_control = ccmsg;
	msg.msg_controllen = sizeof(ccmsg);

	while(((rv = recvmsg(fd, &msg, 0)) == -1) && errno == EINTR);
	if (rv == -1) {
		fuse_log(FUSE_LOG_ERR, "recvmsg failed: %s", strerror(errno));
		return -1;
	}
	if(!rv) {
		/* EOF */
		return -1;
	}

	cmsg = CMSG_FIRSTHDR(&msg);
	if (cmsg->cmsg_type != SCM_RIGHTS) {
		fuse_log(FUSE_LOG_ERR, "got control message of unknown type %d\n",
			cmsg->cmsg_type);
		return -1;
	}
	return *(int*)CMSG_DATA(cmsg);
}

void fuse_kern_unmount(const char *mountpoint, int fd)
{
	int res;

	if (fd != -1) {
		struct pollfd pfd;

		pfd.fd = fd;
		pfd.events = 0;
		res = poll(&pfd, 1, 0);

		/* Need to close file descriptor, otherwise synchronous umount
		   would recurse into filesystem, and deadlock.

		   Caller expects fuse_kern_unmount to close the fd, so close it
		   anyway. */
		close(fd);

		/* If file poll returns POLLERR on the device file descriptor,
		   then the filesystem is already unmounted or the connection
		   was severed via /sys/fs/fuse/connections/NNN/abort */
		if (res == 1 && (pfd.revents & POLLERR))
			return;
	}

	if (geteuid() == 0) {
		fuse_mnt_umount("fuse", mountpoint, mountpoint,  1);
		return;
	}

	res = umount2(mountpoint, 2);
	if (res == 0)
		return;

	char const * const argv[] =
		{ FUSERMOUNT_PROG, "--unmount", "--quiet", "--lazy",
				"--", mountpoint, NULL };
	int status = fusermount_posix_spawn(NULL, argv, NULL);
	if(status != 0) {
		fuse_log(FUSE_LOG_ERR, "Spawning %s to unmount failed: %s",
			 FUSERMOUNT_PROG, strerror(-status));
		return;
	}
}

static int setup_auto_unmount(const char *mountpoint, int quiet)
{
	int fds[2];
	pid_t pid;
	int res;

	if (!mountpoint) {
		fuse_log(FUSE_LOG_ERR, "fuse: missing mountpoint parameter\n");
		return -1;
	}

	res = socketpair(PF_UNIX, SOCK_STREAM, 0, fds);
	if(res == -1) {
		fuse_log(FUSE_LOG_ERR, "Setting up auto-unmountsocketpair() failed",
			 strerror(errno));
		return -1;
	}

	char arg_fd_entry[30];
	snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[0]);
	setenv(FUSE_COMMFD_ENV, arg_fd_entry, 1);
	/*
	 * This helps to identify the FD hold by parent process.
	 * In auto-unmount case, parent process can close this FD explicitly to do unmount.
	 * The FD[1] can be got via getenv(FUSE_COMMFD2_ENV).
	 * One potential use case is to satisfy FD-Leak checks.
	 */
	snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[1]);
	setenv(FUSE_COMMFD2_ENV, arg_fd_entry, 1);

	char const *const argv[] = {
		FUSERMOUNT_PROG,
		"--auto-unmount",
		"--",
		mountpoint,
		NULL,
	};

	// TODO: add error handling for all manipulations of action.
	posix_spawn_file_actions_t action;
	posix_spawn_file_actions_init(&action);

	if (quiet) {
		posix_spawn_file_actions_addopen(&action, STDOUT_FILENO, "/dev/null", O_WRONLY, 0);
		posix_spawn_file_actions_addopen(&action, STDERR_FILENO, "/dev/null", O_WRONLY, 0);
	}
	posix_spawn_file_actions_addclose(&action, fds[1]);

	/*
	 * auto-umount runs in the background - it is not waiting for the
	 * process
	 */
	int status = fusermount_posix_spawn(&action, argv, &pid);

	posix_spawn_file_actions_destroy(&action);

	if(status != 0) {
		close(fds[0]);
		close(fds[1]);
		fuse_log(FUSE_LOG_ERR, "fuse: Setting up auto-unmount failed (spawn): %s",
			     strerror(-status));
		return -1;
	}
	// passed to child now, so can close here.
	close(fds[0]);

	// Now fusermount3 will only exit when fds[1] closes automatically when our
	// process exits.
	return 0;
	// Note: fds[1] is leakend and doesn't get FD_CLOEXEC
}

static int fuse_mount_fusermount(const char *mountpoint, struct mount_opts *mo,
		const char *opts, int quiet)
{
	int fds[2];
	pid_t pid;
	int res;

	if (!mountpoint) {
		fuse_log(FUSE_LOG_ERR, "fuse: missing mountpoint parameter\n");
		return -1;
	}

	res = socketpair(PF_UNIX, SOCK_STREAM, 0, fds);
	if(res == -1) {
		fuse_log(FUSE_LOG_ERR, "Running %s: socketpair() failed: %s\n",
			 FUSERMOUNT_PROG, strerror(errno));
		return -1;
	}

	char arg_fd_entry[30];
	snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[0]);
	setenv(FUSE_COMMFD_ENV, arg_fd_entry, 1);
	/*
	 * This helps to identify the FD hold by parent process.
	 * In auto-unmount case, parent process can close this FD explicitly to do unmount.
	 * The FD[1] can be got via getenv(FUSE_COMMFD2_ENV).
	 * One potential use case is to satisfy FD-Leak checks.
	 */
	snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[1]);
	setenv(FUSE_COMMFD2_ENV, arg_fd_entry, 1);

	char const *const argv[] = {
		FUSERMOUNT_PROG,
		"-o", opts ? opts : "",
		"--",
		mountpoint,
		NULL,
	};


	posix_spawn_file_actions_t action;
	posix_spawn_file_actions_init(&action);

	if (quiet) {
		posix_spawn_file_actions_addopen(&action, STDOUT_FILENO, "/dev/null", O_WRONLY, 0);
		posix_spawn_file_actions_addopen(&action, STDERR_FILENO, "/dev/null", O_WRONLY, 0);
	}
	posix_spawn_file_actions_addclose(&action, fds[1]);

	int status = fusermount_posix_spawn(&action, argv, &pid);

	posix_spawn_file_actions_destroy(&action);

	if(status != 0) {
		close(fds[0]);
		close(fds[1]);
		fuse_log(FUSE_LOG_ERR, "posix_spawn(p)() for %s failed: %s",
			 FUSERMOUNT_PROG, strerror(-status));
		return -1;
	}

	// passed to child now, so can close here.
	close(fds[0]);

	int fd = receive_fd(fds[1]);

	if (!mo->auto_unmount) {
		/* with auto_unmount option fusermount3 will not exit until
		   this socket is closed */
		close(fds[1]);
		waitpid(pid, NULL, 0); /* bury zombie */
	}

	if (fd >= 0)
		fcntl(fd, F_SETFD, FD_CLOEXEC);

	return fd;
}

#ifndef O_CLOEXEC
#define O_CLOEXEC 0
#endif

static char *escape_context_commas_precise(const char *opts_in)
{
    if (!opts_in) return NULL;
    const char *ctx = strstr(opts_in, "context=");
    if (!ctx) return NULL;

    const char *val = ctx + 8; /* hinter "context=" */
    const char *end = opts_in + strlen(opts_in);

    /* Tokens, die nach context= vorkommen können */
    static const char *tokens[] = {
        ",fd=", ",rootmode=", ",user_id=", ",group_id=",
        ",fsname=", ",subtype=", ",rw", ",ro",
        ",allow_other", ",default_permissions", ",auto_unmount",
        ",kernel_cache", ",attr_timeout=", ",entry_timeout=", ",negative_timeout=",
        NULL
    };

    /* finde frühestes Auftreten eines Tokens hinter val */
    const char *limit = end;
    for (int i = 0; tokens[i]; i++) {
        const char *p = strstr(val, tokens[i]);
        if (p && p < limit) limit = p;
    }

    /* Falls nichts gefunden: der Rest der Zeichenkette ist der context-Wert */
    size_t prefix_len = (size_t)(val - opts_in);
    size_t ctx_len    = (size_t)(limit - val);
    size_t suffix_len = (size_t)(end - limit);

    /* worst case: jedes ',' → "\054" (×4) innerhalb des ctx-Bereichs */
    size_t cap = prefix_len + ctx_len * 4 + suffix_len + 1;
    char *out = malloc(cap);
    if (!out) return NULL;

    /* kopiere prefix (inkl. "context=") */
    memcpy(out, opts_in, prefix_len);
    size_t o = prefix_len;

    /* escapen innerhalb des context-Werts */
    for (size_t i = 0; i < ctx_len; i++) {
        char c = val[i];
        if (c == ',') { memcpy(out + o, "\\054", 4); o += 4; }
        else          { out[o++] = c; }
    }

    /* suffix roh übernehmen */
    memcpy(out + o, limit, suffix_len);
    o += suffix_len;
    out[o] = '\0';
    return out;
}

static int fuse_mount_sys(const char *mnt, struct mount_opts *mo,
			  const char *mnt_opts)
{
	char tmp[128];
	const char *devname = "/dev/fuse";
	char *source = NULL;
	char *type = NULL;
	struct stat stbuf;
	int fd;
	int res;

	if (!mnt) {
		fuse_log(FUSE_LOG_ERR, "fuse: missing mountpoint parameter\n");
		return -1;
	}

	res = stat(mnt, &stbuf);
	if (res == -1) {
		fuse_log(FUSE_LOG_ERR, "fuse: failed to access mountpoint %s: %s\n",
			mnt, strerror(errno));
		return -1;
	}

	fd = open(devname, O_RDWR | O_CLOEXEC);
	if (fd == -1) {
		if (errno == ENODEV || errno == ENOENT)
			fuse_log(FUSE_LOG_ERR, "fuse: device not found, try 'modprobe fuse' first\n");
		else
			fuse_log(FUSE_LOG_ERR, "fuse: failed to open %s: %s\n",
				devname, strerror(errno));
		return -1;
	}
	if (!O_CLOEXEC)
		fcntl(fd, F_SETFD, FD_CLOEXEC);

	snprintf(tmp, sizeof(tmp),  "fd=%i,rootmode=%o,user_id=%u,group_id=%u",
		 fd, stbuf.st_mode & S_IFMT, getuid(), getgid());

	res = fuse_opt_add_opt(&mo->kernel_opts, tmp);
	if (res == -1)
		goto out_close;

	source = malloc((mo->fsname ? strlen(mo->fsname) : 0) +
			(mo->subtype ? strlen(mo->subtype) : 0) +
			strlen(devname) + 32);

	type = malloc((mo->subtype ? strlen(mo->subtype) : 0) + 32);
	if (!type || !source) {
		fuse_log(FUSE_LOG_ERR, "fuse: failed to allocate memory\n");
		goto out_close;
	}

	strcpy(type, mo->blkdev ? "fuseblk" : "fuse");
	if (mo->subtype) {
		strcat(type, ".");
		strcat(type, mo->subtype);
	}
	strcpy(source,
	       mo->fsname ? mo->fsname : (mo->subtype ? mo->subtype : devname));

#if defined(__linux__)
    /* Erst neue Mount-API probieren: jede Option (inkl. context=… mit Kommata)
    wird als separates K/V gesetzt – keine Ambiguität mehr. */
    if (fuse_mount_with_fsopen_try(type, mnt, mo->kernel_opts, mo->flags) == 0) {
        res = 0;
    } else
#endif
    {
        if (mo->kernel_opts) {
            char *escaped = escape_context_commas_precise(mo->kernel_opts);
            if (escaped) {
                free(mo->kernel_opts);
                mo->kernel_opts = escaped;
            }
        }
        /* Fallback: klassisches mount(2) mit kommaseparierter Optionskette */
        res = mount(source, mnt, type, mo->flags, mo->kernel_opts);
    }

	if (res == -1 && errno == ENODEV && mo->subtype) {
		/* Probably missing subtype support */
		strcpy(type, mo->blkdev ? "fuseblk" : "fuse");
		if (mo->fsname) {
			if (!mo->blkdev)
				sprintf(source, "%s#%s", mo->subtype,
					mo->fsname);
		} else {
			strcpy(source, type);
		}
		res = mount(source, mnt, type, mo->flags, mo->kernel_opts);
	}
	if (res == -1) {
		/*
		 * Maybe kernel doesn't support unprivileged mounts, in this
		 * case try falling back to fusermount3
		 */
		if (errno == EPERM) {
			res = -2;
		} else {
			int errno_save = errno;
			if (mo->blkdev && errno == ENODEV &&
			    !fuse_mnt_check_fuseblk())
				fuse_log(FUSE_LOG_ERR,
					"fuse: 'fuseblk' support missing\n");
			else
				fuse_log(FUSE_LOG_ERR, "fuse: mount failed: %s\n",
					strerror(errno_save));
		}

		goto out_close;
	}

#ifndef IGNORE_MTAB
	if (geteuid() == 0) {
		char *newmnt = fuse_mnt_resolve_path("fuse", mnt);
		res = -1;
		if (!newmnt)
			goto out_umount;

		res = fuse_mnt_add_mount("fuse", source, newmnt, type,
					 mnt_opts);
		free(newmnt);
		if (res == -1)
			goto out_umount;
	}
#endif /* IGNORE_MTAB */
	free(type);
	free(source);

	return fd;

out_umount:
	umount2(mnt, 2); /* lazy umount */
out_close:
	free(type);
	free(source);
	close(fd);
	return res;
}

static int get_mnt_flag_opts(char **mnt_optsp, int flags)
{
	int i;

	if (!(flags & MS_RDONLY) && fuse_opt_add_opt(mnt_optsp, "rw") == -1)
		return -1;

	for (i = 0; mount_flags[i].opt != NULL; i++) {
		if (mount_flags[i].on && (flags & mount_flags[i].flag) &&
		    fuse_opt_add_opt(mnt_optsp, mount_flags[i].opt) == -1)
			return -1;
	}
	return 0;
}

struct mount_opts *parse_mount_opts(struct fuse_args *args)
{
	struct mount_opts *mo;

	mo = (struct mount_opts*) malloc(sizeof(struct mount_opts));
	if (mo == NULL)
		return NULL;

	memset(mo, 0, sizeof(struct mount_opts));
	mo->flags = MS_NOSUID | MS_NODEV;

	if (args &&
	    fuse_opt_parse(args, mo, fuse_mount_opts, fuse_mount_opt_proc) == -1)
		goto err_out;

	return mo;

err_out:
	destroy_mount_opts(mo);
	return NULL;
}

void destroy_mount_opts(struct mount_opts *mo)
{
	free(mo->fsname);
	free(mo->subtype);
	free(mo->fusermount_opts);
	free(mo->subtype_opt);
	free(mo->kernel_opts);
	free(mo->mtab_opts);
	free(mo);
}


int fuse_kern_mount(const char *mountpoint, struct mount_opts *mo)
{
	int res = -1;
	char *mnt_opts = NULL;

	res = -1;
	if (get_mnt_flag_opts(&mnt_opts, mo->flags) == -1)
		goto out;
	if (mo->kernel_opts && fuse_opt_add_opt(&mnt_opts, mo->kernel_opts) == -1)
		goto out;
	if (mo->mtab_opts &&  fuse_opt_add_opt(&mnt_opts, mo->mtab_opts) == -1)
		goto out;

	res = fuse_mount_sys(mountpoint, mo, mnt_opts);
	if (res >= 0 && mo->auto_unmount) {
		if(0 > setup_auto_unmount(mountpoint, 0)) {
			// Something went wrong, let's umount like in fuse_mount_sys.
			umount2(mountpoint, MNT_DETACH); /* lazy umount */
			res = -1;
		}
	} else if (res == -2) {
		if (mo->fusermount_opts &&
		    fuse_opt_add_opt(&mnt_opts, mo->fusermount_opts) == -1)
			goto out;

		if (mo->subtype) {
			char *tmp_opts = NULL;

			res = -1;
			if (fuse_opt_add_opt(&tmp_opts, mnt_opts) == -1 ||
			    fuse_opt_add_opt(&tmp_opts, mo->subtype_opt) == -1) {
				free(tmp_opts);
				goto out;
			}

			res = fuse_mount_fusermount(mountpoint, mo, tmp_opts, 1);
			free(tmp_opts);
			if (res == -1)
				res = fuse_mount_fusermount(mountpoint, mo,
							    mnt_opts, 0);
		} else {
			res = fuse_mount_fusermount(mountpoint, mo, mnt_opts, 0);
		}
	}
out:
	free(mnt_opts);
	return res;
}