Merge pull request #3909 from poettering/mount-tool

add a new tool for creating transient mount and automount units

1 files changed, 1112 insertions, 0 deletions

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;
+}