diff options
Diffstat (limited to 'src/grp-system/libcore/path.c')
| -rw-r--r-- | src/grp-system/libcore/path.c | 784 |
1 files changed, 784 insertions, 0 deletions
diff --git a/src/grp-system/libcore/path.c b/src/grp-system/libcore/path.c new file mode 100644 index 0000000000..0dd0d375d8 --- /dev/null +++ b/src/grp-system/libcore/path.c @@ -0,0 +1,784 @@ +/*** + 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 <errno.h> +#include <sys/epoll.h> +#include <sys/inotify.h> +#include <unistd.h> + +#include "bus-error.h" +#include "bus-util.h" +#include "dbus-path.h" +#include "fd-util.h" +#include "fs-util.h" +#include "glob-util.h" +#include "macro.h" +#include "mkdir.h" +#include "path.h" +#include "special.h" +#include "stat-util.h" +#include "string-table.h" +#include "string-util.h" +#include "unit-name.h" +#include "unit.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->event_source, s->inotify_fd, EPOLLIN, handler, s); + if (r < 0) + goto fail; + + (void) sd_event_source_set_description(s->event_source, "path"); + + /* 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; + } + + r = log_warning_errno(errno, "Failed to add watch on %s: %s", s->path, errno == ENOSPC ? "too many watches" : strerror(-r)); + 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'; + + (void) 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) { + r = log_error_errno(errno, "Failed to add watch on any of the components of %s: %m", s->path); + /* 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); + s->inotify_fd = safe_close(s->inotify_fd); +} + +int path_spec_fd_event(PathSpec *s, uint32_t revents) { + union inotify_event_buffer buffer; + struct inotify_event *e; + ssize_t l; + int r = 0; + + if (revents != EPOLLIN) { + log_error("Got invalid poll event on inotify."); + return -EINVAL; + } + + l = read(s->inotify_fd, &buffer, sizeof(buffer)); + if (l < 0) { + if (errno == EAGAIN || errno == EINTR) + return 0; + + return log_error_errno(errno, "Failed to read inotify event: %m"); + } + + FOREACH_INOTIFY_EVENT(e, buffer, l) { + if ((s->type == PATH_CHANGED || s->type == PATH_MODIFIED) && + s->primary_wd == e->wd) + r = 1; + } + + 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_errno(r, "mkdir(%s) failed: %m", s->path); +} + +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_unit_error(UNIT(p), "Path unit lacks path setting. Refusing."); + return -EINVAL; + } + + return 0; +} + +static int path_add_default_dependencies(Path *p) { + int r; + + assert(p); + + if (!UNIT(p)->default_dependencies) + return 0; + + r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE, SPECIAL_PATHS_TARGET, NULL, true); + if (r < 0) + return r; + + if (MANAGER_IS_SYSTEM(UNIT(p)->manager)) { + 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; + + 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_unit_debug(UNIT(p), "Changed %s -> %s", 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_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL; + Unit *trigger; + int r; + + assert(p); + + /* Don't start job if we are supposed to go down */ + if (unit_stop_pending(UNIT(p))) + return; + + trigger = UNIT_TRIGGER(UNIT(p)); + if (!trigger) { + log_unit_error(UNIT(p), "Unit to trigger vanished."); + path_enter_dead(p, PATH_FAILURE_RESOURCES); + return; + } + + r = manager_add_job(UNIT(p)->manager, JOB_START, trigger, JOB_REPLACE, &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_unit_warning(UNIT(p), "Failed to queue unit startup job: %s", 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_unit_debug(UNIT(p), "Got triggered."); + 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_unit_debug(UNIT(p), "Got triggered."); + path_enter_running(p); + return; + } + + path_set_state(p, PATH_WAITING); + return; + +fail: + log_unit_warning_errno(UNIT(p), r, "Failed to enter waiting state: %m"); + 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); + Unit *trigger; + int r; + + assert(p); + assert(p->state == PATH_DEAD || p->state == PATH_FAILED); + + trigger = UNIT_TRIGGER(u); + if (!trigger || trigger->load_state != UNIT_LOADED) { + log_unit_error(u, "Refusing to start, unit to trigger not loaded."); + return -ENOENT; + } + + r = unit_start_limit_test(u); + if (r < 0) { + path_enter_dead(p, PATH_FAILURE_START_LIMIT_HIT); + return r; + } + + path_mkdir(p); + + p->result = PATH_SUCCESS; + path_enter_waiting(p, true, true); + + return 1; +} + +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 1; +} + +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_unit_debug(u, "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_unit_debug(u, "Failed to parse result value: %s", value); + else if (f != PATH_SUCCESS) + p->result = f; + + } else + log_unit_debug(u, "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_unit_debug(UNIT(p), "Got notified about unit deactivation."); + + /* 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_type_table[_PATH_TYPE_MAX] = { + [PATH_EXISTS] = "PathExists", + [PATH_EXISTS_GLOB] = "PathExistsGlob", + [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty", + [PATH_CHANGED] = "PathChanged", + [PATH_MODIFIED] = "PathModified", +}; + +DEFINE_STRING_TABLE_LOOKUP(path_type, PathType); + +static const char* const path_result_table[_PATH_RESULT_MAX] = { + [PATH_SUCCESS] = "success", + [PATH_FAILURE_RESOURCES] = "resources", + [PATH_FAILURE_START_LIMIT_HIT] = "start-limit-hit", +}; + +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_vtable = bus_path_vtable +}; |