systemd/mount.c

/*-*- Mode: C; c-basic-offset: 8 -*-*/

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 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
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <errno.h>
#include <stdio.h>
#include <mntent.h>
#include <sys/epoll.h>
#include <sys/poll.h>

#include "unit.h"
#include "mount.h"
#include "load-fragment.h"
#include "load-dropin.h"
#include "log.h"

static const UnitActiveState state_translation_table[_MOUNT_STATE_MAX] = {
        [MOUNT_DEAD] = UNIT_INACTIVE,
        [MOUNT_MOUNTING] = UNIT_ACTIVATING,
        [MOUNT_MOUNTED] = UNIT_ACTIVE,
        [MOUNT_UNMOUNTING] = UNIT_DEACTIVATING,
        [MOUNT_MAINTAINANCE] = UNIT_INACTIVE,
};

static const char* const state_string_table[_MOUNT_STATE_MAX] = {
        [MOUNT_DEAD] = "dead",
        [MOUNT_MOUNTING] = "mounting",
        [MOUNT_MOUNTED] = "mounted",
        [MOUNT_UNMOUNTING] = "unmounting",
        [MOUNT_MAINTAINANCE] = "maintainance"
};

static void mount_done(Unit *u) {
        Mount *m = MOUNT(u);

        assert(m);
        free(m->what);
        free(m->where);
}

static void mount_set_state(Mount *m, MountState state) {
        MountState old_state;
        assert(m);

        if (state == m->state)
                return;

        old_state = m->state;
        m->state = state;

        log_debug("%s changed %s → %s", unit_id(UNIT(m)), state_string_table[old_state], state_string_table[state]);

        unit_notify(UNIT(m), state_translation_table[old_state], state_translation_table[state]);
}

static int mount_coldplug(Unit *u) {
        Mount *m = MOUNT(u);

        assert(m);
        assert(m->state == MOUNT_DEAD);

        if (m->from_proc_self_mountinfo)
                mount_set_state(m, MOUNT_MOUNTED);

        return 0;
}

static void mount_dump(Unit *u, FILE *f, const char *prefix) {
        Mount *s = MOUNT(u);

        assert(s);

        fprintf(f,
                "%sMount State: %s\n"
                "%sWhere: %s\n"
                "%sWhat: %s\n"
                "%sFrom /etc/fstab: %s\n"
                "%sFrom /proc/self/mountinfo: %s\n",
                prefix, state_string_table[s->state],
                prefix, s->where,
                prefix, s->what,
                prefix, yes_no(s->from_etc_fstab),
                prefix, yes_no(s->from_proc_self_mountinfo));
}

static UnitActiveState mount_active_state(Unit *u) {
        assert(u);

        return state_translation_table[MOUNT(u)->state];
}

static void mount_shutdown(Manager *m) {
        assert(m);

        if (m->proc_self_mountinfo)
                fclose(m->proc_self_mountinfo);
}

static int mount_add_node_links(Mount *m) {
        Unit *device;
        char *e;
        int r;

        assert(m);

        /* Adds in links to the device that this node is based on */

        if (!path_startswith(m->what, "/dev/"))
                return 0;

        if (!(e = unit_name_escape_path(m->what+1, ".device")))
                return -ENOMEM;

        r = manager_load_unit(UNIT(m)->meta.manager, e, &device);
        free(e);

        if (r < 0)
                return r;

        if ((r = unit_add_dependency(UNIT(m), UNIT_AFTER, device)) < 0)
                return r;

        if ((r = unit_add_dependency(UNIT(m), UNIT_REQUIRES, device)) < 0)
                return r;

        if ((r = unit_add_dependency(device, UNIT_WANTS, UNIT(m))) < 0)
                return r;

        return 0;
}

static int mount_add_path_links(Mount *m) {
        Meta *other;
        int r;

        /* Adds in link to other mount points, that might lie below or
         * above us in the hierarchy */

        LIST_FOREACH(units_per_type, other, UNIT(m)->meta.manager->units_per_type[UNIT_MOUNT]) {
                Mount *n;

                n = (Mount*) other;

                if (n == m)
                        continue;

                if (path_startswith(m->where, n->where)) {

                        if ((r = unit_add_dependency(UNIT(m), UNIT_AFTER, (Unit*) other)) < 0)
                                return r;

                        if ((r = unit_add_dependency(UNIT(m), UNIT_REQUIRES, (Unit*) other)) < 0)
                                return r;

                } else if (startswith(n->where, m->where)) {

                        if ((r = unit_add_dependency(UNIT(m), UNIT_BEFORE, (Unit*) other)) < 0)
                                return r;

                        if ((r = unit_add_dependency((Unit*) other, UNIT_REQUIRES, UNIT(m))) < 0)
                                return r;
                }
        }

        return 0;
}

static int mount_add_one(Manager *m, const char *what, const char *where, bool live, bool set_flags) {
        char *e;
        int r;
        Unit *u;
        bool delete;

        assert(m);
        assert(what);
        assert(where);

        /* probably some kind of swap, which we don't cover for now */
        if (where[0] != '/')
                return 0;

        if (streq(where, "/"))
                e = strdup("-.mount");
        else
                e = unit_name_escape_path(where+1, ".mount");

        if (!e)
                return -ENOMEM;

        if (!(u = manager_get_unit(m, e))) {
                delete = true;

                if (!(u = unit_new(m))) {
                        free(e);
                        return -ENOMEM;
                }

                r = unit_add_name(u, e);
                free(e);

                if (r < 0)
                        goto fail;

                if (!(MOUNT(u)->what = strdup(what)) ||
                    !(MOUNT(u)->where = strdup(where))) {
                            r = -ENOMEM;
                            goto fail;
                    }

                if ((r = unit_set_description(u, where)) < 0)
                        goto fail;

                unit_add_to_load_queue(u);
        } else {
                delete = false;
                free(e);
        }

        if (set_flags)
                MOUNT(u)->still_exists = true;

        if (live) {
                if (set_flags)
                        MOUNT(u)->just_created = !MOUNT(u)->from_proc_self_mountinfo;
                MOUNT(u)->from_proc_self_mountinfo = true;
        } else {
                if (set_flags)
                        MOUNT(u)->just_created = !MOUNT(u)->from_etc_fstab;
                MOUNT(u)->from_etc_fstab = true;
        }

        if ((r = mount_add_node_links(MOUNT(u))) < 0)
                goto fail;

        if ((r = mount_add_path_links(MOUNT(u))) < 0)
                goto fail;

        unit_add_to_dbus_queue(u);

        return 0;

fail:
        if (delete && u)
                unit_free(u);

        return 0;
}

static char *fstab_node_to_udev_node(char *p) {
        char *dn, *t;
        int r;

        /* FIXME: to follow udev's logic 100% we need to leave valid
         * UTF8 chars unescaped */

        if (startswith(p, "LABEL=")) {

                if (!(t = xescape(p+6, "/ ")))
                        return NULL;

                r = asprintf(&dn, "/dev/disk/by-label/%s", t);
                free(t);

                if (r < 0)
                        return NULL;

                return dn;
        }

        if (startswith(p, "UUID=")) {

                if (!(t = xescape(p+5, "/ ")))
                        return NULL;

                r = asprintf(&dn, "/dev/disk/by-uuid/%s", ascii_strlower(t));
                free(t);

                if (r < 0)
                        return NULL;

                return dn;
        }

        return strdup(p);
}

static int mount_load_etc_fstab(Manager *m, bool set_flags) {
        FILE *f;
        int r;
        struct mntent* me;

        assert(m);

        errno = 0;
        if (!(f = setmntent("/etc/fstab", "r")))
                return -errno;

        while ((me = getmntent(f))) {
                char *where, *what;

                if (!(what = fstab_node_to_udev_node(me->mnt_fsname))) {
                        r = -ENOMEM;
                        goto finish;
                }

                if (!(where = strdup(me->mnt_dir))) {
                        free(what);
                        r = -ENOMEM;
                        goto finish;
                }

                if (what[0] == '/')
                        path_kill_slashes(what);

                if (where[0] == '/')
                        path_kill_slashes(where);

                r = mount_add_one(m, what, where, false, set_flags);
                free(what);
                free(where);

                if (r < 0)
                        goto finish;
        }

        r = 0;
finish:

        endmntent(f);
        return r;
}

static int mount_load_proc_self_mountinfo(Manager *m, bool set_flags) {
        int r;

        assert(m);

        rewind(m->proc_self_mountinfo);

        for (;;) {
                int k;
                char *device, *path, *d, *p;

                if ((k = fscanf(m->proc_self_mountinfo,
                                "%*s "       /* (1) mount id */
                                "%*s "       /* (2) parent id */
                                "%*s "       /* (3) major:minor */
                                "%*s "       /* (4) root */
                                "%ms "       /* (5) mount point */
                                "%*s"        /* (6) mount options */
                                "%*[^-]"     /* (7) optional fields */
                                "- "         /* (8) seperator */
                                "%*s "       /* (9) file system type */
                                "%ms"        /* (10) mount source */
                                "%*[^\n]",   /* some rubbish at the end */
                                &path,
                                &device)) != 2) {

                        if (k == EOF)
                                break;

                        return -EBADMSG;
                }

                if (!(d = cunescape(device))) {
                        free(device);
                        free(path);
                        return -ENOMEM;
                }
                free(device);

                if (!(p = cunescape(path))) {
                        free(d);
                        free(path);
                        return -ENOMEM;
                }
                free(path);

                r = mount_add_one(m, d, p, true, set_flags);
                free(d);
                free(p);

                if (r < 0)
                        return r;
        }

        return 0;
}

static int mount_enumerate(Manager *m) {
        int r;
        struct epoll_event ev;
        assert(m);

        if (!(m->proc_self_mountinfo = fopen("/proc/self/mountinfo", "r")))
                return -errno;

        m->mount_watch.type = WATCH_MOUNT;
        m->mount_watch.fd = fileno(m->proc_self_mountinfo);

        zero(ev);
        ev.events = EPOLLERR;
        ev.data.ptr = &m->mount_watch;

        if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->mount_watch.fd, &ev) < 0)
                return -errno;

        if ((r = mount_load_etc_fstab(m, false)) < 0)
                goto fail;

        if ((r = mount_load_proc_self_mountinfo(m, false)) < 0)
                goto fail;

        return 0;

fail:
        mount_shutdown(m);
        return r;
}

void mount_fd_event(Manager *m, int events) {
        Meta *meta;
        int r;

        assert(m);
        assert(events == EPOLLERR);

        /* The manager calls this for every fd event happening on the
         * /proc/self/mountinfo file, which informs us about mounting
         * table changes */

        if ((r = mount_load_proc_self_mountinfo(m, true)) < 0) {
                log_error("Failed to reread /proc/self/mountinfo: %s", strerror(-errno));
                return;
        }

        manager_dispatch_load_queue(m);

        LIST_FOREACH(units_per_type, meta, m->units_per_type[UNIT_MOUNT]) {
                Mount *mount = (Mount*) meta;

                if (mount->just_created && mount->state == MOUNT_DEAD)
                        mount_set_state(mount, MOUNT_MOUNTED);
                else if (!mount->still_exists && mount->state == MOUNT_MOUNTED) {
                        mount_set_state(mount, MOUNT_DEAD);
                        mount->from_proc_self_mountinfo = false;
                }

                /* Clear the flags for later calls */
                mount->just_created = false;
                mount->still_exists = false;
        }
}

const UnitVTable mount_vtable = {
        .suffix = ".mount",

        .init = unit_load_fragment_and_dropin_optional,
        .done = mount_done,
        .coldplug = mount_coldplug,

        .dump = mount_dump,

        .active_state = mount_active_state,

        .enumerate = mount_enumerate,
        .shutdown = mount_shutdown
};