add a new tool for creating transient mount and automount units

This adds "systemd-mount" which is for transient mount and automount units what
"systemd-run" is for transient service, scope and timer units.

The tool allows establishing mounts and automounts during runtime. It is very
similar to the usual /bin/mount commands, but can pull in additional
dependenices on access (for example, it pulls in fsck automatically), an take
benefit of the automount logic.

This tool is particularly useful for mount removable file systems (such as USB
sticks), as the automount logic (together with automatic unmount-on-idle), as
well as automatic fsck on first access ensure that the removable file system
has a high chance to remain in a fully clean state even when it is unplugged
abruptly, and returns to a clean state on the next re-plug.

This is a follow-up for #2471, as it adds a simple client-side for the
transient automount logic added in that PR.

In later work it might make sense to invoke this tool automatically from udev
rules in order to implement a simpler and safer version of removable media
management á la udisks.

2 files changed, 1113 insertions, 0 deletions

diff --git a/src/mount/Makefile b/src/mount/Makefile
new file mode 120000
index 0000000000..d0b0e8e008
--- /dev/null
+++ b/src/mount/Makefile
@@ -0,0 +1 @@
+../Makefile
\ No newline at end of file
diff --git a/src/mount/mount-tool.c b/src/mount/mount-tool.c
new file mode 100644
index 0000000000..9076ba3b0b
--- /dev/null
+++ b/src/mount/mount-tool.c
@@ -0,0 +1,1112 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <getopt.h>
+
+#include "libudev.h"
+#include "sd-bus.h"
+
+#include "bus-error.h"
+#include "bus-unit-util.h"
+#include "bus-util.h"
+#include "escape.h"
+#include "fstab-util.h"
+#include "pager.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "spawn-polkit-agent.h"
+#include "strv.h"
+#include "udev-util.h"
+#include "unit-name.h"
+#include "terminal-util.h"
+
+enum {
+        ACTION_DEFAULT,
+        ACTION_MOUNT,
+        ACTION_AUTOMOUNT,
+        ACTION_LIST,
+} arg_action = ACTION_DEFAULT;
+
+static bool arg_no_block = false;
+static bool arg_no_pager = false;
+static bool arg_ask_password = true;
+static bool arg_quiet = false;
+static BusTransport arg_transport = BUS_TRANSPORT_LOCAL;
+static bool arg_user = false;
+static const char *arg_host = NULL;
+static bool arg_discover = false;
+static char *arg_mount_what = NULL;
+static char *arg_mount_where = NULL;
+static char *arg_mount_type = NULL;
+static char *arg_mount_options = NULL;
+static char *arg_description = NULL;
+static char **arg_property = NULL;
+static usec_t arg_timeout_idle = USEC_INFINITY;
+static bool arg_timeout_idle_set = false;
+static char **arg_automount_property = NULL;
+static int arg_bind_device = -1;
+static bool arg_fsck = true;
+
+static void polkit_agent_open_if_enabled(void) {
+
+        /* Open the polkit agent as a child process if necessary */
+        if (!arg_ask_password)
+                return;
+
+        if (arg_transport != BUS_TRANSPORT_LOCAL)
+                return;
+
+        polkit_agent_open();
+}
+
+static void help(void) {
+        printf("%s [OPTIONS...] WHAT [WHERE]\n\n"
+               "Establish a mount or auto-mount point transiently.\n\n"
+               "  -h --help                       Show this help\n"
+               "     --version                    Show package version\n"
+               "     --no-block                   Do not wait until operation finished\n"
+               "     --no-pager                   Do not pipe output into a pager\n"
+               "     --no-ask-password            Do not prompt for password\n"
+               "  -q --quiet                      Suppress information messages during runtime\n"
+               "     --user                       Run as user unit\n"
+               "  -H --host=[USER@]HOST           Operate on remote host\n"
+               "  -M --machine=CONTAINER          Operate on local container\n"
+               "     --discover                   Discover mount device metadata\n"
+               "  -t --type=TYPE                  File system type\n"
+               "  -o --options=OPTIONS            Mount options\n"
+               "     --fsck=no                    Don't run file system check before mount\n"
+               "     --description=TEXT           Description for unit\n"
+               "  -p --property=NAME=VALUE        Set mount unit property\n"
+               "  -A --automount=BOOL             Create an auto-mount point\n"
+               "     --timeout-idle-sec=SEC       Specify automount idle timeout\n"
+               "     --automount-property=NAME=VALUE\n"
+               "                                  Set automount unit property\n"
+               "     --bind-device                Bind automount unit to device\n"
+               "     --list                       List mountable block devices\n"
+               , program_invocation_short_name);
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+        enum {
+                ARG_VERSION = 0x100,
+                ARG_NO_BLOCK,
+                ARG_NO_PAGER,
+                ARG_NO_ASK_PASSWORD,
+                ARG_USER,
+                ARG_SYSTEM,
+                ARG_DISCOVER,
+                ARG_MOUNT_TYPE,
+                ARG_MOUNT_OPTIONS,
+                ARG_FSCK,
+                ARG_DESCRIPTION,
+                ARG_TIMEOUT_IDLE,
+                ARG_AUTOMOUNT,
+                ARG_AUTOMOUNT_PROPERTY,
+                ARG_BIND_DEVICE,
+                ARG_LIST,
+        };
+
+        static const struct option options[] = {
+                { "help",               no_argument,       NULL, 'h'                    },
+                { "version",            no_argument,       NULL, ARG_VERSION            },
+                { "no-block",           no_argument,       NULL, ARG_NO_BLOCK           },
+                { "no-pager",           no_argument,       NULL, ARG_NO_PAGER           },
+                { "no-ask-password",    no_argument,       NULL, ARG_NO_ASK_PASSWORD    },
+                { "quiet",              no_argument,       NULL, 'q'                    },
+                { "user",               no_argument,       NULL, ARG_USER               },
+                { "system",             no_argument,       NULL, ARG_SYSTEM             },
+                { "host",               required_argument, NULL, 'H'                    },
+                { "machine",            required_argument, NULL, 'M'                    },
+                { "discover",           no_argument,       NULL, ARG_DISCOVER           },
+                { "type",               required_argument, NULL, 't'                    },
+                { "options",            required_argument, NULL, 'o'                    },
+                { "description",        required_argument, NULL, ARG_DESCRIPTION        },
+                { "property",           required_argument, NULL, 'p'                    },
+                { "automount",          required_argument, NULL, ARG_AUTOMOUNT          },
+                { "timeout-idle-sec",   required_argument, NULL, ARG_TIMEOUT_IDLE       },
+                { "automount-property", required_argument, NULL, ARG_AUTOMOUNT_PROPERTY },
+                { "bind-device",        no_argument,       NULL, ARG_BIND_DEVICE        },
+                { "list",               no_argument,       NULL, ARG_LIST               },
+                {},
+        };
+
+        int r, c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "hqH:M:t:o:p:A", options, NULL)) >= 0)
+
+                switch (c) {
+
+                case 'h':
+                        help();
+                        return 0;
+
+                case ARG_VERSION:
+                        return version();
+
+                case ARG_NO_BLOCK:
+                        arg_no_block = true;
+                        break;
+
+                case ARG_NO_PAGER:
+                        arg_no_pager = true;
+                        break;
+
+                case ARG_NO_ASK_PASSWORD:
+                        arg_ask_password = false;
+                        break;
+
+                case 'q':
+                        arg_quiet = true;
+                        break;
+
+                case ARG_USER:
+                        arg_user = true;
+                        break;
+
+                case ARG_SYSTEM:
+                        arg_user = false;
+                        break;
+
+                case 'H':
+                        arg_transport = BUS_TRANSPORT_REMOTE;
+                        arg_host = optarg;
+                        break;
+
+                case 'M':
+                        arg_transport = BUS_TRANSPORT_MACHINE;
+                        arg_host = optarg;
+                        break;
+
+                case ARG_DISCOVER:
+                        arg_discover = true;
+                        break;
+
+                case 't':
+                        if (free_and_strdup(&arg_mount_type, optarg) < 0)
+                                return log_oom();
+                        break;
+
+                case 'o':
+                        if (free_and_strdup(&arg_mount_options, optarg) < 0)
+                                return log_oom();
+                        break;
+
+                case ARG_FSCK:
+                        r = parse_boolean(optarg);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to parse --fsck= argument: %s", optarg);
+
+                        arg_fsck = r;
+                        break;
+
+                case ARG_DESCRIPTION:
+                        if (free_and_strdup(&arg_description, optarg) < 0)
+                                return log_oom();
+                        break;
+
+                case 'p':
+                        if (strv_extend(&arg_property, optarg) < 0)
+                                return log_oom();
+
+                        break;
+
+                case 'A':
+                        arg_action = ACTION_AUTOMOUNT;
+                        break;
+
+                case ARG_AUTOMOUNT:
+                        r = parse_boolean(optarg);
+                        if (r < 0)
+                                return log_error_errno(r, "--automount= expects a valid boolean parameter: %s", optarg);
+
+                        arg_action = r ? ACTION_AUTOMOUNT : ACTION_MOUNT;
+                        break;
+
+                case ARG_TIMEOUT_IDLE:
+                        r = parse_sec(optarg, &arg_timeout_idle);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to parse timeout: %s", optarg);
+
+                        break;
+
+                case ARG_AUTOMOUNT_PROPERTY:
+                        if (strv_extend(&arg_automount_property, optarg) < 0)
+                                return log_oom();
+
+                        break;
+
+                case ARG_BIND_DEVICE:
+                        arg_bind_device = true;
+                        break;
+
+                case ARG_LIST:
+                        arg_action = ACTION_LIST;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+
+        if (arg_user && arg_transport != BUS_TRANSPORT_LOCAL) {
+                log_error("Execution in user context is not supported on non-local systems.");
+                return -EINVAL;
+        }
+
+        if (arg_action == ACTION_LIST) {
+                if (optind < argc) {
+                        log_error("Too many arguments.");
+                        return -EINVAL;
+                }
+
+                if (arg_transport != BUS_TRANSPORT_LOCAL) {
+                        log_error("Listing devices only supported locally.");
+                        return -EOPNOTSUPP;
+                }
+        } else {
+                if (optind >= argc) {
+                        log_error("At least one argument required.");
+                        return -EINVAL;
+                }
+
+                if (argc > optind+2) {
+                        log_error("At most two arguments required.");
+                        return -EINVAL;
+                }
+
+                arg_mount_what = fstab_node_to_udev_node(argv[optind]);
+                if (!arg_mount_what)
+                        return log_oom();
+
+                if (argc > optind+1) {
+                        r = path_make_absolute_cwd(argv[optind+1], &arg_mount_where);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to make path absolute: %m");
+                } else
+                        arg_discover = true;
+
+                if (arg_discover && arg_transport != BUS_TRANSPORT_LOCAL) {
+                        log_error("Automatic mount location discovery is only supported locally.");
+                        return -EOPNOTSUPP;
+                }
+        }
+
+        return 1;
+}
+
+static int transient_unit_set_properties(sd_bus_message *m, char **properties) {
+        int r;
+
+        r = sd_bus_message_append(m, "(sv)", "Description", "s", arg_description);
+        if (r < 0)
+                return r;
+
+        if (arg_bind_device && is_device_path(arg_mount_what)) {
+                _cleanup_free_ char *device_unit = NULL;
+
+                r = unit_name_from_path(arg_mount_what, ".device", &device_unit);
+                if (r < 0)
+                        return r;
+
+                r = sd_bus_message_append(m, "(sv)(sv)",
+                                          "After", "as", 1, device_unit,
+                                          "BindsTo", "as", 1, device_unit);
+                if (r < 0)
+                        return r;
+        }
+
+        r = bus_append_unit_property_assignment_many(m, properties);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int transient_mount_set_properties(sd_bus_message *m) {
+        int r;
+
+        assert(m);
+
+        r = transient_unit_set_properties(m, arg_property);
+        if (r < 0)
+                return r;
+
+        if (arg_mount_what) {
+                r = sd_bus_message_append(m, "(sv)", "What", "s", arg_mount_what);
+                if (r < 0)
+                        return r;
+        }
+
+        if (arg_mount_type) {
+                r = sd_bus_message_append(m, "(sv)", "Type", "s", arg_mount_type);
+                if (r < 0)
+                        return r;
+        }
+
+        if (arg_mount_options) {
+                r = sd_bus_message_append(m, "(sv)", "Options", "s", arg_mount_options);
+                if (r < 0)
+                        return r;
+        }
+
+        if (arg_fsck) {
+                _cleanup_free_ char *fsck = NULL;
+
+                r = unit_name_from_path_instance("systemd-fsck", arg_mount_what, ".service", &fsck);
+                if (r < 0)
+                        return r;
+
+                r = sd_bus_message_append(m,
+                                          "(sv)(sv)",
+                                          "Requires", "as", 1, fsck,
+                                          "After", "as", 1, fsck);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int transient_automount_set_properties(sd_bus_message *m) {
+        int r;
+
+        assert(m);
+
+        r = transient_unit_set_properties(m, arg_automount_property);
+        if (r < 0)
+                return r;
+
+        if (arg_timeout_idle != USEC_INFINITY) {
+                r = sd_bus_message_append(m, "(sv)", "TimeoutIdleUSec", "t", arg_timeout_idle);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int start_transient_mount(
+                sd_bus *bus,
+                char **argv) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(bus_wait_for_jobs_freep) BusWaitForJobs *w = NULL;
+        _cleanup_free_ char *mount_unit = NULL;
+        int r;
+
+        if (!arg_no_block) {
+                r = bus_wait_for_jobs_new(bus, &w);
+                if (r < 0)
+                        return log_error_errno(r, "Could not watch jobs: %m");
+        }
+
+        r = unit_name_from_path(arg_mount_where, ".mount", &mount_unit);
+        if (r < 0)
+                return log_error_errno(r, "Failed to make mount unit name: %m");
+
+        r = sd_bus_message_new_method_call(
+                        bus,
+                        &m,
+                        "org.freedesktop.systemd1",
+                        "/org/freedesktop/systemd1",
+                        "org.freedesktop.systemd1.Manager",
+                        "StartTransientUnit");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_set_allow_interactive_authorization(m, arg_ask_password);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        /* Name and mode */
+        r = sd_bus_message_append(m, "ss", mount_unit, "fail");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        /* Properties */
+        r = sd_bus_message_open_container(m, 'a', "(sv)");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = transient_mount_set_properties(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        /* Auxiliary units */
+        r = sd_bus_message_append(m, "a(sa(sv))", 0);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        polkit_agent_open_if_enabled();
+
+        r = sd_bus_call(bus, m, 0, &error, &reply);
+        if (r < 0)
+                return log_error_errno(r, "Failed to start transient mount unit: %s", bus_error_message(&error, r));
+
+        if (w) {
+                const char *object;
+
+                r = sd_bus_message_read(reply, "o", &object);
+                if (r < 0)
+                        return bus_log_parse_error(r);
+
+                r = bus_wait_for_jobs_one(w, object, arg_quiet);
+                if (r < 0)
+                        return r;
+        }
+
+        if (!arg_quiet)
+                log_info("Started unit %s%s%s for mount point: %s%s%s",
+                         ansi_highlight(), mount_unit, ansi_normal(),
+                         ansi_highlight(), arg_mount_where, ansi_normal());
+
+        return 0;
+}
+
+static int start_transient_automount(
+                sd_bus *bus,
+                char **argv) {
+
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(bus_wait_for_jobs_freep) BusWaitForJobs *w = NULL;
+        _cleanup_free_ char *automount_unit = NULL, *mount_unit = NULL;
+        int r;
+
+        if (!arg_no_block) {
+                r = bus_wait_for_jobs_new(bus, &w);
+                if (r < 0)
+                        return log_error_errno(r, "Could not watch jobs: %m");
+        }
+
+        r = unit_name_from_path(arg_mount_where, ".automount", &automount_unit);
+        if (r < 0)
+                return log_error_errno(r, "Failed to make automount unit name: %m");
+
+        r = unit_name_from_path(arg_mount_where, ".mount", &mount_unit);
+        if (r < 0)
+                return log_error_errno(r, "Failed to make mount unit name: %m");
+
+        r = sd_bus_message_new_method_call(
+                        bus,
+                        &m,
+                        "org.freedesktop.systemd1",
+                        "/org/freedesktop/systemd1",
+                        "org.freedesktop.systemd1.Manager",
+                        "StartTransientUnit");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_set_allow_interactive_authorization(m, arg_ask_password);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        /* Name and mode */
+        r = sd_bus_message_append(m, "ss", automount_unit, "fail");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        /* Properties */
+        r = sd_bus_message_open_container(m, 'a', "(sv)");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = transient_automount_set_properties(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        /* Auxiliary units */
+        r = sd_bus_message_open_container(m, 'a', "(sa(sv))");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_open_container(m, 'r', "sa(sv)");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_append(m, "s", mount_unit);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_open_container(m, 'a', "(sv)");
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = transient_mount_set_properties(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        r = sd_bus_message_close_container(m);
+        if (r < 0)
+                return bus_log_create_error(r);
+
+        polkit_agent_open_if_enabled();
+
+        r = sd_bus_call(bus, m, 0, &error, &reply);
+        if (r < 0)
+                return log_error_errno(r, "Failed to start transient automount unit: %s", bus_error_message(&error, r));
+
+        if (w) {
+                const char *object;
+
+                r = sd_bus_message_read(reply, "o", &object);
+                if (r < 0)
+                        return bus_log_parse_error(r);
+
+                r = bus_wait_for_jobs_one(w, object, arg_quiet);
+                if (r < 0)
+                        return r;
+        }
+
+        if (!arg_quiet)
+                log_info("Started unit %s%s%s for mount point: %s%s%s",
+                         ansi_highlight(), automount_unit, ansi_normal(),
+                         ansi_highlight(), arg_mount_where, ansi_normal());
+
+        return 0;
+}
+
+static int acquire_mount_type(struct udev_device *d) {
+        const char *v;
+
+        assert(d);
+
+        if (arg_mount_type)
+                return 0;
+
+        v = udev_device_get_property_value(d, "ID_FS_TYPE");
+        if (isempty(v))
+                return 0;
+
+        arg_mount_type = strdup(v);
+        if (!arg_mount_type)
+                return log_oom();
+
+        log_debug("Discovered type=%s", arg_mount_type);
+        return 1;
+}
+
+static int acquire_mount_options(struct udev_device *d) {
+        const char *v;
+
+        if (arg_mount_options)
+                return 0;
+
+        v = udev_device_get_property_value(d, "SYSTEMD_MOUNT_OPTIONS");
+        if (isempty(v))
+                return 0;
+
+        arg_mount_options = strdup(v);
+        if (!arg_mount_options)
+                return log_oom();
+
+        log_debug("Discovered options=%s", arg_mount_options);
+        return 1;
+}
+
+static const char *get_model(struct udev_device *d) {
+        const char *model;
+
+        assert(d);
+
+        model = udev_device_get_property_value(d, "ID_MODEL_FROM_DATABASE");
+        if (model)
+                return model;
+
+        return udev_device_get_property_value(d, "ID_MODEL");
+}
+
+static const char* get_label(struct udev_device *d) {
+        const char *label;
+
+        assert(d);
+
+        label = udev_device_get_property_value(d, "ID_FS_LABEL");
+        if (label)
+                return label;
+
+        return udev_device_get_property_value(d, "ID_PART_ENTRY_NAME");
+}
+
+static int acquire_mount_where(struct udev_device *d) {
+        const char *v;
+
+        if (arg_mount_where)
+                return 0;
+
+        v = udev_device_get_property_value(d, "SYSTEMD_MOUNT_WHERE");
+        if (isempty(v)) {
+                _cleanup_free_ char *escaped = NULL;
+                const char *name;
+
+                name = get_label(d);
+                if (!name)
+                        name = get_model(d);
+                if (!name) {
+                        const char *dn;
+
+                        dn = udev_device_get_devnode(d);
+                        if (!dn)
+                                return 0;
+
+                        name = basename(dn);
+                }
+
+                escaped = xescape(name, "\\");
+                if (!filename_is_valid(escaped))
+                        return 0;
+
+                arg_mount_where = strjoin("/run/media/system/", escaped, NULL);
+        } else
+                arg_mount_where = strdup(v);
+
+        if (!arg_mount_where)
+                return log_oom();
+
+        log_debug("Discovered where=%s", arg_mount_where);
+        return 1;
+}
+
+static int acquire_description(struct udev_device *d) {
+        const char *model, *label;
+
+        if (arg_description)
+                return 0;
+
+        model = get_model(d);
+
+        label = get_label(d);
+        if (!label)
+                label = udev_device_get_property_value(d, "ID_PART_ENTRY_NUMBER");
+
+        if (model && label)
+                arg_description = strjoin(model, " ", label, NULL);
+        else if (label)
+                arg_description = strdup(label);
+        else if (model)
+                arg_description = strdup(model);
+        else
+                return NULL;
+
+        if (!arg_description)
+                return log_oom();
+
+        log_debug("Discovered description=%s", arg_description);
+        return 1;
+}
+
+static int acquire_removable(struct udev_device *d) {
+        const char *v;
+
+        /* Shortcut this if there's no reason to check it */
+        if (arg_action != ACTION_DEFAULT && arg_timeout_idle_set && arg_bind_device >= 0)
+                return 0;
+
+        for (;;) {
+                v = udev_device_get_sysattr_value(d, "removable");
+                if (v)
+                        break;
+
+                d = udev_device_get_parent(d);
+                if (!d)
+                        return 0;
+
+                if (!streq_ptr(udev_device_get_subsystem(d), "block"))
+                        return 0;
+        }
+
+        if (parse_boolean(v) <= 0)
+                return 0;
+
+        log_debug("Discovered removable device.");
+
+        if (arg_action == ACTION_DEFAULT) {
+                log_debug("Automatically turning on automount.");
+                arg_action = ACTION_AUTOMOUNT;
+        }
+
+        if (!arg_timeout_idle_set) {
+                log_debug("Setting idle timeout to 1s.");
+                arg_timeout_idle = USEC_PER_SEC;
+        }
+
+        if (arg_bind_device < 0) {
+                log_debug("Binding automount unit to device.");
+                arg_bind_device = true;
+        }
+
+        return 1;
+}
+
+static int discover_device(void) {
+        _cleanup_udev_device_unref_ struct udev_device *d = NULL;
+        _cleanup_udev_unref_ struct udev *udev = NULL;
+        struct stat st;
+        const char *v;
+        int r;
+
+        if (!arg_discover)
+                return 0;
+
+        if (!is_device_path(arg_mount_what)) {
+                log_error("Discovery only supported for block devices, don't know what to do.");
+                return -EINVAL;
+        }
+
+        if (stat(arg_mount_what, &st) < 0)
+                return log_error_errno(errno, "Can't stat %s: %m", arg_mount_what);
+
+        if (!S_ISBLK(st.st_mode)) {
+                log_error("Path %s is not a block device, don't know what to do.", arg_mount_what);
+                return -ENOTBLK;
+        }
+
+        udev = udev_new();
+        if (!udev)
+                return log_oom();
+
+        d = udev_device_new_from_devnum(udev, 'b', st.st_rdev);
+        if (!d)
+                return log_oom();
+
+        v = udev_device_get_property_value(d, "ID_FS_USAGE");
+        if (!streq_ptr(v, "filesystem")) {
+                log_error("%s does not contain a file system.", arg_mount_what);
+                return -EINVAL;
+        }
+
+        r = acquire_mount_type(d);
+        if (r < 0)
+                return r;
+
+        r = acquire_mount_options(d);
+        if (r < 0)
+                return r;
+
+        r = acquire_mount_where(d);
+        if (r < 0)
+                return r;
+
+        r = acquire_description(d);
+        if (r < 0)
+                return r;
+
+        r = acquire_removable(d);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+enum {
+        COLUMN_NODE,
+        COLUMN_PATH,
+        COLUMN_MODEL,
+        COLUMN_WWN,
+        COLUMN_FSTYPE,
+        COLUMN_LABEL,
+        COLUMN_UUID,
+        _COLUMN_MAX,
+};
+
+struct item {
+        char* columns[_COLUMN_MAX];
+};
+
+static int compare_item(const void *a, const void *b) {
+        const struct item *x = a, *y = b;
+
+        if (x->columns[COLUMN_NODE] == y->columns[COLUMN_NODE])
+                return 0;
+        if (!x->columns[COLUMN_NODE])
+                return 1;
+        if (!y->columns[COLUMN_NODE])
+                return -1;
+
+        return path_compare(x->columns[COLUMN_NODE], y->columns[COLUMN_NODE]);
+}
+
+static int list_devices(void) {
+
+        static const char * const titles[_COLUMN_MAX] = {
+                [COLUMN_NODE] = "NODE",
+                [COLUMN_PATH] = "PATH",
+                [COLUMN_MODEL] = "MODEL",
+                [COLUMN_WWN] = "WWN",
+                [COLUMN_FSTYPE] = "TYPE",
+                [COLUMN_LABEL] = "LABEL",
+                [COLUMN_UUID] = "UUID"
+        };
+
+        _cleanup_udev_enumerate_unref_ struct udev_enumerate *e = NULL;
+        _cleanup_udev_unref_ struct udev *udev = NULL;
+        struct udev_list_entry *item = NULL, *first = NULL;
+        size_t n_allocated = 0, n = 0, i;
+        size_t column_width[_COLUMN_MAX];
+        struct item *items = NULL;
+        unsigned c;
+        int r;
+
+        for (c = 0; c < _COLUMN_MAX; c++)
+                column_width[c] = strlen(titles[c]);
+
+        udev = udev_new();
+        if (!udev)
+                return log_oom();
+
+        e = udev_enumerate_new(udev);
+        if (!e)
+                return log_oom();
+
+        r = udev_enumerate_add_match_subsystem(e, "block");
+        if (r < 0)
+                return log_error_errno(r, "Failed to add block match: %m");
+
+        r = udev_enumerate_add_match_property(e, "ID_FS_USAGE", "filesystem");
+        if (r < 0)
+                return log_error_errno(r, "Failed to add property match: %m");
+
+        r = udev_enumerate_scan_devices(e);
+        if (r < 0)
+                return log_error_errno(r, "Failed to scan devices: %m");
+
+        first = udev_enumerate_get_list_entry(e);
+        udev_list_entry_foreach(item, first) {
+                _cleanup_udev_device_unref_ struct udev_device *d;
+                struct item *j;
+
+                d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
+                if (!d) {
+                        r = log_oom();
+                        goto finish;
+                }
+
+                if (!GREEDY_REALLOC0(items, n_allocated, n+1)) {
+                        r = log_oom();
+                        goto finish;
+                }
+
+                j = items + n++;
+
+                for (c = 0; c < _COLUMN_MAX; c++) {
+                        const char *x;
+                        size_t k;
+
+                        switch (c) {
+
+                        case COLUMN_NODE:
+                                x = udev_device_get_devnode(d);
+                                break;
+
+                        case COLUMN_PATH:
+                                x = udev_device_get_property_value(d, "ID_PATH");
+                                break;
+
+                        case COLUMN_MODEL:
+                                x = get_model(d);
+                                break;
+
+                        case COLUMN_WWN:
+                                x = udev_device_get_property_value(d, "ID_WWN");
+                                break;
+
+                        case COLUMN_FSTYPE:
+                                x = udev_device_get_property_value(d, "ID_FS_TYPE");
+                                break;
+
+                        case COLUMN_LABEL:
+                                x = get_label(d);
+                                break;
+
+                        case COLUMN_UUID:
+                                x = udev_device_get_property_value(d, "ID_FS_UUID");
+                                break;
+                        }
+
+                        if (isempty(x))
+                                continue;
+
+                        j->columns[c] = strdup(x);
+                        if (!j->columns[c]) {
+                                r = log_oom();
+                                goto finish;
+                        }
+
+                        k = strlen(x);
+                        if (k > column_width[c])
+                                column_width[c] = k;
+                }
+        }
+
+        if (n == 0) {
+                log_info("No devices found.");
+                goto finish;
+        }
+
+        qsort_safe(items, n, sizeof(struct item), compare_item);
+
+        pager_open(arg_no_pager, false);
+
+        fputs(ansi_underline(), stdout);
+        for (c = 0; c < _COLUMN_MAX; c++) {
+                if (c > 0)
+                        fputc(' ', stdout);
+
+                printf("%-*s", (int) column_width[c], titles[c]);
+        }
+        fputs(ansi_normal(), stdout);
+        fputc('\n', stdout);
+
+        for (i = 0; i < n; i++) {
+                for (c = 0; c < _COLUMN_MAX; c++) {
+                        if (c > 0)
+                                fputc(' ', stdout);
+
+                        printf("%-*s", (int) column_width[c], strna(items[i].columns[c]));
+                }
+                fputc('\n', stdout);
+        }
+
+        r = 0;
+
+finish:
+        for (i = 0; i < n; i++)
+                for (c = 0; c < _COLUMN_MAX; c++)
+                        free(items[i].columns[c]);
+
+        free(items);
+        return r;
+}
+
+int main(int argc, char* argv[]) {
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
+        int r;
+
+        log_parse_environment();
+        log_open();
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                goto finish;
+
+        if (arg_action == ACTION_LIST) {
+                r = list_devices();
+                goto finish;
+        }
+
+        r = discover_device();
+        if (r < 0)
+                goto finish;
+        if (!arg_mount_where) {
+                log_error("Can't figure out where to mount %s.", arg_mount_what);
+                r = -EINVAL;
+                goto finish;
+        }
+
+        path_kill_slashes(arg_mount_where);
+
+        if (path_equal(arg_mount_where, "/")) {
+                log_error("Refusing to operate on root directory.");
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (!path_is_safe(arg_mount_where)) {
+                log_error("Path is contains unsafe components.");
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (streq_ptr(arg_mount_type, "auto"))
+                arg_mount_type = mfree(arg_mount_type);
+        if (streq_ptr(arg_mount_options, "defaults"))
+                arg_mount_options = mfree(arg_mount_options);
+
+        if (!is_device_path(arg_mount_what))
+                arg_fsck = false;
+
+        if (arg_fsck && arg_mount_type && arg_transport == BUS_TRANSPORT_LOCAL) {
+                r = fsck_exists(arg_mount_type);
+                if (r < 0)
+                        log_warning_errno(r, "Couldn't determine whether fsck for %s exists, proceeding anyway.", arg_mount_type);
+                else if (r == 0) {
+                        log_debug("Disabling file system check as fsck for %s doesn't exist.", arg_mount_type);
+                        arg_fsck = false; /* fsck doesn't exist, let's not attempt it */
+                }
+        }
+
+        r = bus_connect_transport_systemd(arg_transport, arg_host, arg_user, &bus);
+        if (r < 0) {
+                log_error_errno(r, "Failed to create bus connection: %m");
+                goto finish;
+        }
+
+        switch (arg_action) {
+
+        case ACTION_MOUNT:
+        case ACTION_DEFAULT:
+                r = start_transient_mount(bus, argv + optind);
+                break;
+
+        case ACTION_AUTOMOUNT:
+                r = start_transient_automount(bus, argv + optind);
+                break;
+
+        default:
+                assert_not_reached("Unexpected action.");
+        }
+
+finish:
+        bus = sd_bus_flush_close_unref(bus);
+
+        pager_close();
+
+        free(arg_mount_what);
+        free(arg_mount_where);
+        free(arg_mount_type);
+        free(arg_mount_options);
+        free(arg_description);
+        strv_free(arg_property);
+        strv_free(arg_automount_property);
+
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}