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Systemd/src/core/path.c

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
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 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 <sys/inotify.h>
#include <sys/epoll.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <unistd.h>
#include "unit.h"
#include "unit-name.h"
#include "path.h"
#include "mkdir.h"
#include "dbus-path.h"
#include "special.h"
#include "path-util.h"
#include "macro.h"
#include "bus-util.h"
#include "bus-error.h"
static const UnitActiveState state_translation_table[_PATH_STATE_MAX] = {
[PATH_DEAD] = UNIT_INACTIVE,
[PATH_WAITING] = UNIT_ACTIVE,
[PATH_RUNNING] = UNIT_ACTIVE,
[PATH_FAILED] = UNIT_FAILED
};
static int path_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata);
int path_spec_watch(PathSpec *s, sd_event_io_handler_t handler) {
static const int flags_table[_PATH_TYPE_MAX] = {
[PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
[PATH_EXISTS_GLOB] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
[PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
[PATH_MODIFIED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO|IN_MODIFY,
[PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO
};
bool exists = false;
char *slash, *oldslash = NULL;
int r;
assert(s);
assert(s->unit);
assert(handler);
path_spec_unwatch(s);
s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
if (s->inotify_fd < 0) {
r = -errno;
goto fail;
}
r = sd_event_add_io(s->unit->manager->event, s->inotify_fd, EPOLLIN, handler, s, &s->event_source);
if (r < 0)
goto fail;
/* This assumes the path was passed through path_kill_slashes()! */
for (slash = strchr(s->path, '/'); ; slash = strchr(slash+1, '/')) {
char *cut = NULL;
int flags;
char tmp;
if (slash) {
cut = slash + (slash == s->path);
tmp = *cut;
*cut = '\0';
flags = IN_MOVE_SELF | IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
} else
flags = flags_table[s->type];
r = inotify_add_watch(s->inotify_fd, s->path, flags);
if (r < 0) {
if (errno == EACCES || errno == ENOENT) {
if (cut)
*cut = tmp;
break;
}
log_warning("Failed to add watch on %s: %m", s->path);
r = -errno;
if (cut)
*cut = tmp;
goto fail;
} else {
exists = true;
/* Path exists, we don't need to watch parent
too closely. */
if (oldslash) {
char *cut2 = oldslash + (oldslash == s->path);
char tmp2 = *cut2;
*cut2 = '\0';
inotify_add_watch(s->inotify_fd, s->path, IN_MOVE_SELF);
/* Error is ignored, the worst can happen is
we get spurious events. */
*cut2 = tmp2;
}
}
if (cut)
*cut = tmp;
if (slash)
oldslash = slash;
else {
/* whole path has been iterated over */
s->primary_wd = r;
break;
}
}
if (!exists) {
log_error("Failed to add watch on any of the components of %s: %m",
s->path);
r = -errno; /* either EACCESS or ENOENT */
goto fail;
}
return 0;
fail:
path_spec_unwatch(s);
return r;
}
void path_spec_unwatch(PathSpec *s) {
assert(s);
s->event_source = sd_event_source_unref(s->event_source);
if (s->inotify_fd >= 0) {
close_nointr_nofail(s->inotify_fd);
s->inotify_fd = -1;
}
}
int path_spec_fd_event(PathSpec *s, uint32_t revents) {
_cleanup_free_ uint8_t *buf = NULL;
struct inotify_event *e;
ssize_t k;
int l;
int r = 0;
if (revents != EPOLLIN) {
log_error("Got invalid poll event on inotify.");
return -EINVAL;
}
if (ioctl(s->inotify_fd, FIONREAD, &l) < 0) {
log_error("FIONREAD failed: %m");
return -errno;
}
assert(l > 0);
buf = malloc(l);
if (!buf)
return log_oom();
k = read(s->inotify_fd, buf, l);
if (k < 0) {
log_error("Failed to read inotify event: %m");
return -errno;
}
e = (struct inotify_event*) buf;
while (k > 0) {
size_t step;
if ((s->type == PATH_CHANGED || s->type == PATH_MODIFIED) &&
s->primary_wd == e->wd)
r = 1;
step = sizeof(struct inotify_event) + e->len;
assert(step <= (size_t) k);
e = (struct inotify_event*) ((uint8_t*) e + step);
k -= step;
}
return r;
}
static bool path_spec_check_good(PathSpec *s, bool initial) {
bool good = false;
switch (s->type) {
case PATH_EXISTS:
good = access(s->path, F_OK) >= 0;
break;
case PATH_EXISTS_GLOB:
good = glob_exists(s->path) > 0;
break;
case PATH_DIRECTORY_NOT_EMPTY: {
int k;
k = dir_is_empty(s->path);
good = !(k == -ENOENT || k > 0);
break;
}
case PATH_CHANGED:
case PATH_MODIFIED: {
bool b;
b = access(s->path, F_OK) >= 0;
good = !initial && b != s->previous_exists;
s->previous_exists = b;
break;
}
default:
;
}
return good;
}
static void path_spec_mkdir(PathSpec *s, mode_t mode) {
int r;
if (s->type == PATH_EXISTS || s->type == PATH_EXISTS_GLOB)
return;
r = mkdir_p_label(s->path, mode);
if (r < 0)
log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
}
static void path_spec_dump(PathSpec *s, FILE *f, const char *prefix) {
fprintf(f,
"%s%s: %s\n",
prefix,
path_type_to_string(s->type),
s->path);
}
void path_spec_done(PathSpec *s) {
assert(s);
assert(s->inotify_fd == -1);
free(s->path);
}
static void path_init(Unit *u) {
Path *p = PATH(u);
assert(u);
assert(u->load_state == UNIT_STUB);
p->directory_mode = 0755;
}
void path_free_specs(Path *p) {
PathSpec *s;
assert(p);
while ((s = p->specs)) {
path_spec_unwatch(s);
LIST_REMOVE(spec, p->specs, s);
path_spec_done(s);
free(s);
}
}
static void path_done(Unit *u) {
Path *p = PATH(u);
assert(p);
path_free_specs(p);
}
static int path_add_mount_links(Path *p) {
PathSpec *s;
int r;
assert(p);
LIST_FOREACH(spec, s, p->specs) {
r = unit_require_mounts_for(UNIT(p), s->path);
if (r < 0)
return r;
}
return 0;
}
static int path_verify(Path *p) {
assert(p);
if (UNIT(p)->load_state != UNIT_LOADED)
return 0;
if (!p->specs) {
log_error_unit(UNIT(p)->id,
"%s lacks path setting. Refusing.", UNIT(p)->id);
return -EINVAL;
}
return 0;
}
static int path_add_default_dependencies(Path *p) {
int r;
assert(p);
r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE,
SPECIAL_PATHS_TARGET, NULL, true);
if (r < 0)
return r;
if (UNIT(p)->manager->running_as == SYSTEMD_SYSTEM) {
r = unit_add_two_dependencies_by_name(UNIT(p), UNIT_AFTER, UNIT_REQUIRES,
SPECIAL_SYSINIT_TARGET, NULL, true);
if (r < 0)
return r;
}
return unit_add_two_dependencies_by_name(UNIT(p), UNIT_BEFORE, UNIT_CONFLICTS,
SPECIAL_SHUTDOWN_TARGET, NULL, true);
}
static int path_load(Unit *u) {
Path *p = PATH(u);
int r;
assert(u);
assert(u->load_state == UNIT_STUB);
r = unit_load_fragment_and_dropin(u);
if (r < 0)
return r;
if (u->load_state == UNIT_LOADED) {
if (set_isempty(u->dependencies[UNIT_TRIGGERS])) {
Unit *x;
r = unit_load_related_unit(u, ".service", &x);
if (r < 0)
return r;
r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, x, true);
if (r < 0)
return r;
}
r = path_add_mount_links(p);
if (r < 0)
return r;
if (UNIT(p)->default_dependencies) {
r = path_add_default_dependencies(p);
if (r < 0)
return r;
}
}
return path_verify(p);
}
static void path_dump(Unit *u, FILE *f, const char *prefix) {
Path *p = PATH(u);
Unit *trigger;
PathSpec *s;
assert(p);
assert(f);
trigger = UNIT_TRIGGER(u);
fprintf(f,
"%sPath State: %s\n"
"%sResult: %s\n"
"%sUnit: %s\n"
"%sMakeDirectory: %s\n"
"%sDirectoryMode: %04o\n",
prefix, path_state_to_string(p->state),
prefix, path_result_to_string(p->result),
prefix, trigger ? trigger->id : "n/a",
prefix, yes_no(p->make_directory),
prefix, p->directory_mode);
LIST_FOREACH(spec, s, p->specs)
path_spec_dump(s, f, prefix);
}
static void path_unwatch(Path *p) {
PathSpec *s;
assert(p);
LIST_FOREACH(spec, s, p->specs)
path_spec_unwatch(s);
}
static int path_watch(Path *p) {
int r;
PathSpec *s;
assert(p);
LIST_FOREACH(spec, s, p->specs) {
r = path_spec_watch(s, path_dispatch_io);
if (r < 0)
return r;
}
return 0;
}
static void path_set_state(Path *p, PathState state) {
PathState old_state;
assert(p);
old_state = p->state;
p->state = state;
if (state != PATH_WAITING &&
(state != PATH_RUNNING || p->inotify_triggered))
path_unwatch(p);
if (state != old_state)
log_debug("%s changed %s -> %s",
UNIT(p)->id,
path_state_to_string(old_state),
path_state_to_string(state));
unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
}
static void path_enter_waiting(Path *p, bool initial, bool recheck);
static int path_coldplug(Unit *u) {
Path *p = PATH(u);
assert(p);
assert(p->state == PATH_DEAD);
if (p->deserialized_state != p->state) {
if (p->deserialized_state == PATH_WAITING ||
p->deserialized_state == PATH_RUNNING)
path_enter_waiting(p, true, true);
else
path_set_state(p, p->deserialized_state);
}
return 0;
}
static void path_enter_dead(Path *p, PathResult f) {
assert(p);
if (f != PATH_SUCCESS)
p->result = f;
path_set_state(p, p->result != PATH_SUCCESS ? PATH_FAILED : PATH_DEAD);
}
static void path_enter_running(Path *p) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
int r;
assert(p);
/* Don't start job if we are supposed to go down */
if (unit_stop_pending(UNIT(p)))
return;
r = manager_add_job(UNIT(p)->manager, JOB_START, UNIT_TRIGGER(UNIT(p)),
JOB_REPLACE, true, &error, NULL);
if (r < 0)
goto fail;
p->inotify_triggered = false;
r = path_watch(p);
if (r < 0)
goto fail;
path_set_state(p, PATH_RUNNING);
return;
fail:
log_warning("%s failed to queue unit startup job: %s",
UNIT(p)->id, bus_error_message(&error, r));
path_enter_dead(p, PATH_FAILURE_RESOURCES);
}
static bool path_check_good(Path *p, bool initial) {
PathSpec *s;
bool good = false;
assert(p);
LIST_FOREACH(spec, s, p->specs) {
good = path_spec_check_good(s, initial);
if (good)
break;
}
return good;
}
static void path_enter_waiting(Path *p, bool initial, bool recheck) {
int r;
if (recheck)
if (path_check_good(p, initial)) {
log_debug("%s got triggered.", UNIT(p)->id);
path_enter_running(p);
return;
}
r = path_watch(p);
if (r < 0)
goto fail;
/* Hmm, so now we have created inotify watches, but the file
* might have appeared/been removed by now, so we must
* recheck */
if (recheck)
if (path_check_good(p, false)) {
log_debug("%s got triggered.", UNIT(p)->id);
path_enter_running(p);
return;
}
path_set_state(p, PATH_WAITING);
return;
fail:
log_warning("%s failed to enter waiting state: %s",
UNIT(p)->id, strerror(-r));
path_enter_dead(p, PATH_FAILURE_RESOURCES);
}
static void path_mkdir(Path *p) {
PathSpec *s;
assert(p);
if (!p->make_directory)
return;
LIST_FOREACH(spec, s, p->specs)
path_spec_mkdir(s, p->directory_mode);
}
static int path_start(Unit *u) {
Path *p = PATH(u);
assert(p);
assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
if (UNIT_TRIGGER(u)->load_state != UNIT_LOADED)
return -ENOENT;
path_mkdir(p);
p->result = PATH_SUCCESS;
path_enter_waiting(p, true, true);
return 0;
}
static int path_stop(Unit *u) {
Path *p = PATH(u);
assert(p);
assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
path_enter_dead(p, PATH_SUCCESS);
return 0;
}
static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
Path *p = PATH(u);
assert(u);
assert(f);
assert(fds);
unit_serialize_item(u, f, "state", path_state_to_string(p->state));
unit_serialize_item(u, f, "result", path_result_to_string(p->result));
return 0;
}
static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
Path *p = PATH(u);
assert(u);
assert(key);
assert(value);
assert(fds);
if (streq(key, "state")) {
PathState state;
state = path_state_from_string(value);
if (state < 0)
log_debug("Failed to parse state value %s", value);
else
p->deserialized_state = state;
} else if (streq(key, "result")) {
PathResult f;
f = path_result_from_string(value);
if (f < 0)
log_debug("Failed to parse result value %s", value);
else if (f != PATH_SUCCESS)
p->result = f;
} else
log_debug("Unknown serialization key '%s'", key);
return 0;
}
_pure_ static UnitActiveState path_active_state(Unit *u) {
assert(u);
return state_translation_table[PATH(u)->state];
}
_pure_ static const char *path_sub_state_to_string(Unit *u) {
assert(u);
return path_state_to_string(PATH(u)->state);
}
static int path_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
PathSpec *s = userdata;
Path *p;
int changed;
assert(s);
assert(s->unit);
assert(fd >= 0);
p = PATH(s->unit);
if (p->state != PATH_WAITING &&
p->state != PATH_RUNNING)
return 0;
/* log_debug("inotify wakeup on %s.", u->id); */
LIST_FOREACH(spec, s, p->specs)
if (path_spec_owns_inotify_fd(s, fd))
break;
if (!s) {
log_error("Got event on unknown fd.");
goto fail;
}
changed = path_spec_fd_event(s, revents);
if (changed < 0)
goto fail;
/* If we are already running, then remember that one event was
* dispatched so that we restart the service only if something
* actually changed on disk */
p->inotify_triggered = true;
if (changed)
path_enter_running(p);
else
path_enter_waiting(p, false, true);
return 0;
fail:
path_enter_dead(p, PATH_FAILURE_RESOURCES);
return 0;
}
static void path_trigger_notify(Unit *u, Unit *other) {
Path *p = PATH(u);
assert(u);
assert(other);
/* Invoked whenever the unit we trigger changes state or gains
* or loses a job */
if (other->load_state != UNIT_LOADED)
return;
if (p->state == PATH_RUNNING &&
UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other))) {
log_debug_unit(UNIT(p)->id,
"%s got notified about unit deactivation.",
UNIT(p)->id);
/* Hmm, so inotify was triggered since the
* last activation, so I guess we need to
* recheck what is going on. */
path_enter_waiting(p, false, p->inotify_triggered);
}
}
static void path_reset_failed(Unit *u) {
Path *p = PATH(u);
assert(p);
if (p->state == PATH_FAILED)
path_set_state(p, PATH_DEAD);
p->result = PATH_SUCCESS;
}
static const char* const path_state_table[_PATH_STATE_MAX] = {
[PATH_DEAD] = "dead",
[PATH_WAITING] = "waiting",
[PATH_RUNNING] = "running",
[PATH_FAILED] = "failed"
};
DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
static const char* const path_type_table[_PATH_TYPE_MAX] = {
[PATH_EXISTS] = "PathExists",
[PATH_EXISTS_GLOB] = "PathExistsGlob",
[PATH_CHANGED] = "PathChanged",
[PATH_MODIFIED] = "PathModified",
[PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
};
DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
static const char* const path_result_table[_PATH_RESULT_MAX] = {
[PATH_SUCCESS] = "success",
[PATH_FAILURE_RESOURCES] = "resources"
};
DEFINE_STRING_TABLE_LOOKUP(path_result, PathResult);
const UnitVTable path_vtable = {
.object_size = sizeof(Path),
.sections =
"Unit\0"
"Path\0"
"Install\0",
.init = path_init,
.done = path_done,
.load = path_load,
.coldplug = path_coldplug,
.dump = path_dump,
.start = path_start,
.stop = path_stop,
.serialize = path_serialize,
.deserialize_item = path_deserialize_item,
.active_state = path_active_state,
.sub_state_to_string = path_sub_state_to_string,
.trigger_notify = path_trigger_notify,
.reset_failed = path_reset_failed,
.bus_interface = "org.freedesktop.systemd1.Path",
.bus_vtable = bus_path_vtable,
.bus_changing_properties = bus_path_changing_properties
};
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