708961c701
As documented in systemd.path(5):
When a service unit triggered by a path unit terminates (regardless
whether it exited successfully or failed), monitored paths are
checked immediately again, and the service accordingly restarted
instantly.
This commit implements this behaviour for PathExists=, PathExistsGlob=,
and DirectoryNotEmpty=. These predicates are essentially
"level-triggered": the service should be activated whenever the
predicate is true. PathChanged= and PathModified=, on the other hand,
are "edge-triggered": the service should only be activated when the
predicate *becomes* true.
The behaviour has been broken since at least as far back as commit
8fca6944c2 ("path: stop watching path specs once we triggered the target
unit"). This commit had systemd stop monitoring inotify whenever the
triggered unit was activated. Unfortunately this meant it never updated
the ->inotify_triggered flag, so it never rechecked the path specs when
the triggered unit deactivated.
With this commit, systemd rechecks all paths specs whenever the
triggered unit deactivates. If any PathExists=, PathExistsGlob= or
DirectoryNotEmpty= predicate passes, the triggered unit is reactivated.
If the target unit is activated by something outside of the path unit,
the path unit immediately transitions to a running state. This ensures
the path unit stops monitoring inotify in this situation.
With this change in place, commit d7cf8c24d4 ("core/path: fix spurious
triggering of PathExists= on restart/reload") is no longer necessary.
The path unit (and its triggered unit) is now always active whenever
the PathExists= predicate passes, so there is no spurious restart when
systemd is reloaded or restarted.
76 lines
1.6 KiB
C
76 lines
1.6 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#pragma once
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typedef struct Path Path;
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typedef struct PathSpec PathSpec;
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#include "unit.h"
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typedef enum PathType {
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PATH_EXISTS,
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PATH_EXISTS_GLOB,
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PATH_DIRECTORY_NOT_EMPTY,
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PATH_CHANGED,
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PATH_MODIFIED,
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_PATH_TYPE_MAX,
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_PATH_TYPE_INVALID = -1
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} PathType;
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typedef struct PathSpec {
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Unit *unit;
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char *path;
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sd_event_source *event_source;
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LIST_FIELDS(struct PathSpec, spec);
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PathType type;
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int inotify_fd;
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int primary_wd;
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bool previous_exists;
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} PathSpec;
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int path_spec_watch(PathSpec *s, sd_event_io_handler_t handler);
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void path_spec_unwatch(PathSpec *s);
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int path_spec_fd_event(PathSpec *s, uint32_t events);
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void path_spec_done(PathSpec *s);
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static inline bool path_spec_owns_inotify_fd(PathSpec *s, int fd) {
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return s->inotify_fd == fd;
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}
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typedef enum PathResult {
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PATH_SUCCESS,
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PATH_FAILURE_RESOURCES,
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PATH_FAILURE_START_LIMIT_HIT,
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_PATH_RESULT_MAX,
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_PATH_RESULT_INVALID = -1
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} PathResult;
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struct Path {
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Unit meta;
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LIST_HEAD(PathSpec, specs);
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PathState state, deserialized_state;
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bool make_directory;
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mode_t directory_mode;
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PathResult result;
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};
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void path_free_specs(Path *p);
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extern const UnitVTable path_vtable;
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const char* path_type_to_string(PathType i) _const_;
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PathType path_type_from_string(const char *s) _pure_;
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const char* path_result_to_string(PathResult i) _const_;
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PathResult path_result_from_string(const char *s) _pure_;
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DEFINE_CAST(PATH, Path);
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