libfuse: Added support for auto_unmount option

This change adds support for "auto_unmount" option to libfuse.
auto_umount option unmounts the fs automatically on application
termination, whether normal or not (segfault, etc).

When auto_unmount option is specified libfuse will alway use
fusermount for mounting the fs. This change is selfcontained but
for complete functionaly it requires auto_unmount support in
fusermount tool.

diff --git a/lib/mount.c b/lib/mount.c
index 0e585a43665e3733e6ac698a6a133ac1fd32fa89..a159a14a73fc3bc86b94435231a45966b2cb1bd0 100644 (file)
--- a/lib/mount.c
+++ b/lib/mount.c
@@ -68,6 +68,7 @@ struct mount_opts {
        int ishelp;
        int flags;
        int nonempty;
+       int auto_unmount;
        int blkdev;
        char *fsname;
        char *subtype;
@@ -84,11 +85,13 @@ static const struct fuse_opt fuse_mount_opts[] = {
        FUSE_MOUNT_OPT("allow_root",            allow_root),
        FUSE_MOUNT_OPT("nonempty",              nonempty),
        FUSE_MOUNT_OPT("blkdev",                blkdev),
+       FUSE_MOUNT_OPT("auto_unmount",          auto_unmount),
        FUSE_MOUNT_OPT("fsname=%s",             fsname),
        FUSE_MOUNT_OPT("subtype=%s",            subtype),
        FUSE_OPT_KEY("allow_other",             KEY_KERN_OPT),
        FUSE_OPT_KEY("allow_root",              KEY_ALLOW_ROOT),
        FUSE_OPT_KEY("nonempty",                KEY_FUSERMOUNT_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),
@@ -124,6 +127,7 @@ static void mount_help(void)
        fprintf(stderr,
 "    -o allow_other         allow access to other users\n"
 "    -o allow_root          allow access to root\n"
+"    -o auto_unmount        auto unmount on process termination\n"
 "    -o nonempty            allow mounts over non-empty file/dir\n"
 "    -o default_permissions enable permission checking by kernel\n"
 "    -o fsname=NAME         set filesystem name\n"
@@ -334,8 +338,8 @@ void fuse_unmount_compat22(const char *mountpoint)
        fuse_kern_unmount(mountpoint, -1);
 }
 
-static int fuse_mount_fusermount(const char *mountpoint, const char *opts,
-                                int quiet)
+static int fuse_mount_fusermount(const char *mountpoint, struct mount_opts *mo,
+               const char *opts, int quiet)
 {
        int fds[2], pid;
        int res;
@@ -393,15 +397,24 @@ static int fuse_mount_fusermount(const char *mountpoint, const char *opts,
 
        close(fds[0]);
        rv = receive_fd(fds[1]);
-       close(fds[1]);
-       waitpid(pid, NULL, 0); /* bury zombie */
+
+       if (!mo->auto_unmount) {
+               /* with auto_unmount option fusermount will not exit until 
+                  this socket is closed */
+               close(fds[1]);
+               waitpid(pid, NULL, 0); /* bury zombie */
+       }
 
        return rv;
 }
 
 int fuse_mount_compat22(const char *mountpoint, const char *opts)
 {
-       return fuse_mount_fusermount(mountpoint, opts, 0);
+       struct mount_opts mo;
+       memset(&mo, 0, sizeof(mo));
+       mo.flags = MS_NOSUID | MS_NODEV;
+
+       return fuse_mount_fusermount(mountpoint, &mo, opts, 0);
 }
 
 static int fuse_mount_sys(const char *mnt, struct mount_opts *mo,
@@ -434,6 +447,12 @@ static int fuse_mount_sys(const char *mnt, struct mount_opts *mo,
                        return -1;
        }
 
+       if (mo->auto_unmount) {
+               /* Tell the caller to fallback to fusermount because
+                  auto-unmount does not work otherwise. */
+               return -2;
+       }
+
        fd = open(devname, O_RDWR);
        if (fd == -1) {
                if (errno == ENODEV || errno == ENOENT)
@@ -591,13 +610,13 @@ int fuse_kern_mount(const char *mountpoint, struct fuse_args *args)
                                goto out;
                        }
 
-                       res = fuse_mount_fusermount(mountpoint, tmp_opts, 1);
+                       res = fuse_mount_fusermount(mountpoint, &mo, tmp_opts, 1);
                        free(tmp_opts);
                        if (res == -1)
-                               res = fuse_mount_fusermount(mountpoint,
+                               res = fuse_mount_fusermount(mountpoint, &mo,
                                                            mnt_opts, 0);
                } else {
-                       res = fuse_mount_fusermount(mountpoint, mnt_opts, 0);
+                       res = fuse_mount_fusermount(mountpoint, &mo, mnt_opts, 0);
                }
        }
 out: