1 files changed, 227 insertions, 0 deletions
diff --git a/src/libsystemd/sd-event/event-source.h b/src/libsystemd/sd-event/event-source.h
new file mode 100644
index 0000000..6092652
--- /dev/null
+++ b/src/libsystemd/sd-event/event-source.h
@@ -0,0 +1,227 @@
+#pragma once
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/epoll.h>
+#include <sys/timerfd.h>
+#include <sys/wait.h>
+
+#include "sd-event.h"
+
+#include "hashmap.h"
+#include "inotify-util.h"
+#include "list.h"
+#include "prioq.h"
+#include "ratelimit.h"
+
+typedef enum EventSourceType {
+        SOURCE_IO,
+        SOURCE_TIME_REALTIME,
+        SOURCE_TIME_BOOTTIME,
+        SOURCE_TIME_MONOTONIC,
+        SOURCE_TIME_REALTIME_ALARM,
+        SOURCE_TIME_BOOTTIME_ALARM,
+        SOURCE_SIGNAL,
+        SOURCE_CHILD,
+        SOURCE_DEFER,
+        SOURCE_POST,
+        SOURCE_EXIT,
+        SOURCE_WATCHDOG,
+        SOURCE_INOTIFY,
+        _SOURCE_EVENT_SOURCE_TYPE_MAX,
+        _SOURCE_EVENT_SOURCE_TYPE_INVALID = -EINVAL,
+} EventSourceType;
+
+/* All objects we use in epoll events start with this value, so that
+ * we know how to dispatch it */
+typedef enum WakeupType {
+        WAKEUP_NONE,
+        WAKEUP_EVENT_SOURCE, /* either I/O or pidfd wakeup */
+        WAKEUP_CLOCK_DATA,
+        WAKEUP_SIGNAL_DATA,
+        WAKEUP_INOTIFY_DATA,
+        _WAKEUP_TYPE_MAX,
+        _WAKEUP_TYPE_INVALID = -EINVAL,
+} WakeupType;
+
+struct inode_data;
+
+struct sd_event_source {
+        WakeupType wakeup;
+
+        unsigned n_ref;
+
+        sd_event *event;
+        void *userdata;
+        sd_event_handler_t prepare;
+
+        char *description;
+
+        EventSourceType type;
+        signed int enabled:3;
+        bool pending:1;
+        bool dispatching:1;
+        bool floating:1;
+        bool exit_on_failure:1;
+        bool ratelimited:1;
+
+        int64_t priority;
+        unsigned pending_index;
+        unsigned prepare_index;
+        uint64_t pending_iteration;
+        uint64_t prepare_iteration;
+
+        sd_event_destroy_t destroy_callback;
+        sd_event_handler_t ratelimit_expire_callback;
+
+        LIST_FIELDS(sd_event_source, sources);
+
+        RateLimit rate_limit;
+
+        /* These are primarily fields relevant for time event sources, but since any event source can
+         * effectively become one when rate-limited, this is part of the common fields. */
+        unsigned earliest_index;
+        unsigned latest_index;
+
+        union {
+                struct {
+                        sd_event_io_handler_t callback;
+                        int fd;
+                        uint32_t events;
+                        uint32_t revents;
+                        bool registered:1;
+                        bool owned:1;
+                } io;
+                struct {
+                        sd_event_time_handler_t callback;
+                        usec_t next, accuracy;
+                } time;
+                struct {
+                        sd_event_signal_handler_t callback;
+                        struct signalfd_siginfo siginfo;
+                        int sig;
+                        bool unblock;
+                } signal;
+                struct {
+                        sd_event_child_handler_t callback;
+                        siginfo_t siginfo;
+                        pid_t pid;
+                        int options;
+                        int pidfd;
+                        bool registered:1; /* whether the pidfd is registered in the epoll */
+                        bool pidfd_owned:1; /* close pidfd when event source is freed */
+                        bool process_owned:1; /* kill+reap process when event source is freed */
+                        bool exited:1; /* true if process exited (i.e. if there's value in SIGKILLing it if we want to get rid of it) */
+                        bool waited:1; /* true if process was waited for (i.e. if there's value in waitid(P_PID)'ing it if we want to get rid of it) */
+                } child;
+                struct {
+                        sd_event_handler_t callback;
+                } defer;
+                struct {
+                        sd_event_handler_t callback;
+                } post;
+                struct {
+                        sd_event_handler_t callback;
+                        unsigned prioq_index;
+                } exit;
+                struct {
+                        sd_event_inotify_handler_t callback;
+                        uint32_t mask;
+                        struct inode_data *inode_data;
+                        LIST_FIELDS(sd_event_source, by_inode_data);
+                } inotify;
+        };
+};
+
+struct clock_data {
+        WakeupType wakeup;
+        int fd;
+
+        /* For all clocks we maintain two priority queues each, one
+         * ordered for the earliest times the events may be
+         * dispatched, and one ordered by the latest times they must
+         * have been dispatched. The range between the top entries in
+         * the two prioqs is the time window we can freely schedule
+         * wakeups in */
+
+        Prioq *earliest;
+        Prioq *latest;
+        usec_t next;
+
+        bool needs_rearm:1;
+};
+
+struct signal_data {
+        WakeupType wakeup;
+
+        /* For each priority we maintain one signal fd, so that we
+         * only have to dequeue a single event per priority at a
+         * time. */
+
+        int fd;
+        int64_t priority;
+        sigset_t sigset;
+        sd_event_source *current;
+};
+
+/* A structure listing all event sources currently watching a specific inode */
+struct inode_data {
+        /* The identifier for the inode, the combination of the .st_dev + .st_ino fields of the file */
+        ino_t ino;
+        dev_t dev;
+
+        /* An fd of the inode to watch. The fd is kept open until the next iteration of the loop, so that we can
+         * rearrange the priority still until then, as we need the original inode to change the priority as we need to
+         * add a watch descriptor to the right inotify for the priority which we can only do if we have a handle to the
+         * original inode. We keep a list of all inode_data objects with an open fd in the to_close list (see below) of
+         * the sd-event object, so that it is efficient to close everything, before entering the next event loop
+         * iteration. */
+        int fd;
+
+        /* The inotify "watch descriptor" */
+        int wd;
+
+        /* The combination of the mask of all inotify watches on this inode we manage. This is also the mask that has
+         * most recently been set on the watch descriptor. */
+        uint32_t combined_mask;
+
+        /* All event sources subscribed to this inode */
+        LIST_HEAD(sd_event_source, event_sources);
+
+        /* The inotify object we watch this inode with */
+        struct inotify_data *inotify_data;
+
+        /* A linked list of all inode data objects with fds to close (see above) */
+        LIST_FIELDS(struct inode_data, to_close);
+};
+
+/* A structure encapsulating an inotify fd */
+struct inotify_data {
+        WakeupType wakeup;
+
+        /* For each priority we maintain one inotify fd, so that we only have to dequeue a single event per priority at
+         * a time */
+
+        int fd;
+        int64_t priority;
+
+        Hashmap *inodes; /* The inode_data structures keyed by dev+ino */
+        Hashmap *wd;     /* The inode_data structures keyed by the watch descriptor for each */
+
+        /* The buffer we read inotify events into */
+        union inotify_event_buffer buffer;
+        size_t buffer_filled; /* fill level of the buffer */
+
+        /* How many event sources are currently marked pending for this inotify. We won't read new events off the
+         * inotify fd as long as there are still pending events on the inotify (because we have no strategy of queuing
+         * the events locally if they can't be coalesced). */
+        unsigned n_pending;
+
+        /* If this counter is non-zero, don't GC the inotify data object even if not used to watch any inode
+         * anymore. This is useful to pin the object for a bit longer, after the last event source needing it
+         * is gone. */
+        unsigned n_busy;
+
+        /* A linked list of all inotify objects with data already read, that still need processing. We keep this list
+         * to make it efficient to figure out what inotify objects to process data on next. */
+        LIST_FIELDS(struct inotify_data, buffered);
+};