event.c

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/*
 *   This program 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.
 *
 *   This program 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 this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**  Wrapper around libkqueue to make managing events easier
 *
 * Non-thread-safe event handling specific to FreeRADIUS.
 *
 * By non-thread-safe we mean multiple threads can't insert/delete
 * events concurrently into the same event list without synchronization.
 *
 * @file src/lib/util/event.c
 *
 * @copyright 2007-2016 The FreeRADIUS server project
 * @copyright 2016 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 * @copyright 2007 Alan DeKok (aland@freeradius.org)
 */
RCSID("$Id: f0d41fbc2ca603903bde4bf671fcee3b95cf9093 $")
 
#define _EVENT_LIST_PRIVATE 1
typedef struct fr_event_list_s fr_event_list_t;
 
#include <freeradius-devel/util/dlist.h>
#include <freeradius-devel/util/event.h>
#include <freeradius-devel/util/log.h>
#include <freeradius-devel/util/rb.h>
#include <freeradius-devel/util/strerror.h>
#include <freeradius-devel/util/syserror.h>
#include <freeradius-devel/util/token.h>
#include <freeradius-devel/util/atexit.h>
 
#include <sys/stat.h>
#include <sys/wait.h>
 
#ifdef NDEBUG
/*
 *      Turn off documentation warnings as file/line
 *      args aren't used for non-debug builds.
 */
DIAG_OFF(DIAG_UNKNOWN_PRAGMAS)
DIAG_OFF(documentation)
DIAG_ON(DIAG_UNKNOWN_PRAGMAS)
#endif
 
#define FR_EV_BATCH_FDS (256)
 
DIAG_OFF(unused-macros)
#define fr_time() static_assert(0, "Use el->time for event loop timing")
DIAG_ON(unused-macros)
 
#if !defined(SO_GET_FILTER) && defined(SO_ATTACH_FILTER)
#  define SO_GET_FILTER SO_ATTACH_FILTER
#endif
 
static fr_table_num_sorted_t const kevent_filter_table[] = {
#ifdef EVFILT_AIO
        { L("EVFILT_AIO"),      EVFILT_AIO },
#endif
#ifdef EVFILT_EXCEPT
        { L("EVFILT_EXCEPT"),   EVFILT_EXCEPT },
#endif
#ifdef EVFILT_MACHPORT
        { L("EVFILT_MACHPORT"), EVFILT_MACHPORT },
#endif
        { L("EVFILT_PROC"),     EVFILT_PROC },
        { L("EVFILT_READ"),     EVFILT_READ },
        { L("EVFILT_SIGNAL"),   EVFILT_SIGNAL },
        { L("EVFILT_TIMER"),    EVFILT_TIMER },
        { L("EVFILT_VNODE"),    EVFILT_VNODE },
        { L("EVFILT_WRITE"),    EVFILT_WRITE }
};
static size_t kevent_filter_table_len = NUM_ELEMENTS(kevent_filter_table);
 
#ifdef EVFILT_LIBKQUEUE
static int log_conf_kq;
#endif
 
typedef enum {
        FR_EVENT_FD_SOCKET      = 1,                    //!< is a socket.
        FR_EVENT_FD_FILE        = 2,                    //!< is a file.
        FR_EVENT_FD_DIRECTORY   = 4,                    //!< is a directory.
 
#ifdef SO_GET_FILTER
        FR_EVENT_FD_PCAP        = 8,
#endif
} fr_event_fd_type_t;
 
typedef enum {
        FR_EVENT_FUNC_IDX_NONE = 0,
 
        FR_EVENT_FUNC_IDX_FILTER,                       //!< Sign flip is performed i.e. -1 = 0The filter is used
                                                        //// as the index in the ev to func index.
        FR_EVENT_FUNC_IDX_FFLAGS                        //!< The bit position of the flags in FFLAGS
                                                        ///< is used to provide the index.
                                                        ///< i.e. 0x01 -> 0, 0x02 -> 1, 0x08 -> 3 etc..
} fr_event_func_idx_type_t;
 
#ifndef SO_GET_FILTER
#  define FR_EVENT_FD_PCAP      0
#endif
 
/** Specifies a mapping between a function pointer in a structure and its respective event
 *
 * If the function pointer at the specified offset is set, then a matching event
 * will be added.
 *
 * If the function pointer is NULL, then any existing events will be removed.
 */
typedef struct {
        size_t                  offset;                 //!< Offset of function pointer in structure.
        char const              *name;                  //!< Name of the event.
        int16_t                 filter;                 //!< Filter to apply.
        uint16_t                flags;                  //!< Flags to use for inserting event.
        uint32_t                fflags;                 //!< fflags to pass to filter.
        int                     type;                   //!< Type this filter applies to.
        bool                    coalesce;               //!< Coalesce this map with the next.
} fr_event_func_map_entry_t;
 
typedef struct {
        fr_event_func_idx_type_t        idx_type;       //!< What type of index we use for
                                                        ///< event to function mapping.
        fr_event_func_map_entry_t       *func_to_ev;    //!< Function -> Event maps coalesced, out of order.
        fr_event_func_map_entry_t       **ev_to_func;   //!< Function -> Event maps in index order.
} fr_event_func_map_t;
 
static fr_event_func_map_t filter_maps[] = {
        [FR_EVENT_FILTER_IO] = {
                .idx_type = FR_EVENT_FUNC_IDX_FILTER,
                .func_to_ev = (fr_event_func_map_entry_t[]){
                        {
                                .offset         = offsetof(fr_event_io_func_t, read),
                                .name           = "read",
                                .filter         = EVFILT_READ,
                                .flags          = EV_ADD | EV_ENABLE,
#ifdef NOTE_NONE
                                .fflags         = NOTE_NONE,
#else
                                .fflags         = 0,
#endif
                                .type           = FR_EVENT_FD_SOCKET | FR_EVENT_FD_FILE | FR_EVENT_FD_PCAP
                        },
                        {
                                .offset         = offsetof(fr_event_io_func_t, write),
                                .name           = "write",
                                .filter         = EVFILT_WRITE,
                                .flags          = EV_ADD | EV_ENABLE,
                                .fflags         = 0,
                                .type           = FR_EVENT_FD_SOCKET | FR_EVENT_FD_FILE | FR_EVENT_FD_PCAP
                        },
                        { 0 }
                }
        },
        [FR_EVENT_FILTER_VNODE] = {
                .idx_type = FR_EVENT_FUNC_IDX_FFLAGS,
                .func_to_ev = (fr_event_func_map_entry_t[]){
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, delete),
                                .name           = "delete",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_DELETE,
                                .type           = FR_EVENT_FD_FILE | FR_EVENT_FD_DIRECTORY,
                                .coalesce       = true
                        },
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, write),
                                .name           = "write",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_WRITE,
                                .type           = FR_EVENT_FD_FILE,
                                .coalesce       = true
                        },
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, extend),
                                .name           = "extend",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_EXTEND,
                                .type           = FR_EVENT_FD_FILE | FR_EVENT_FD_DIRECTORY,
                                .coalesce       = true
                        },
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, attrib),
                                .name           = "attrib",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_ATTRIB,
                                .type           = FR_EVENT_FD_FILE,
                                .coalesce       = true
                        },
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, link),
                                .name           = "link",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_LINK,
                                .type           = FR_EVENT_FD_FILE,
                                .coalesce       = true
                        },
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, rename),
                                .name           = "rename",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_RENAME,
                                .type           = FR_EVENT_FD_FILE,
                                .coalesce       = true
                        },
#ifdef NOTE_REVOKE
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, revoke),
                                .name           = "revoke",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_REVOKE,
                                .type           = FR_EVENT_FD_FILE,
                                .coalesce       = true
                        },
#endif
#ifdef NOTE_FUNLOCK
                        {
                                .offset         = offsetof(fr_event_vnode_func_t, funlock),
                                .name           = "funlock",
                                .filter         = EVFILT_VNODE,
                                .flags          = EV_ADD | EV_ENABLE | EV_CLEAR,
                                .fflags         = NOTE_FUNLOCK,
                                .type           = FR_EVENT_FD_FILE,
                                .coalesce       = true
                        },
#endif
                        { 0 }
                }
        }
};
 
static fr_table_num_sorted_t const fr_event_fd_type_table[] = {
        { L("directory"),       FR_EVENT_FD_DIRECTORY },
        { L("file"),            FR_EVENT_FD_FILE },
        { L("pcap"),            FR_EVENT_FD_PCAP },
        { L("socket"),          FR_EVENT_FD_SOCKET }
};
static size_t fr_event_fd_type_table_len = NUM_ELEMENTS(fr_event_fd_type_table);
 
/** A file descriptor/filter event
 *
 */
struct fr_event_fd {
        fr_rb_node_t            node;                   //!< Entry in the tree of file descriptor handles.
                                                        ///< this should really go away and we should pass around
                                                        ///< handles directly.
 
        fr_event_list_t         *el;                    //!< Event list this event belongs to.
        fr_event_filter_t       filter;
        int                     fd;                     //!< File descriptor we're listening for events on.
 
        fr_event_fd_type_t      type;                   //!< Type of events we're interested in.
 
        int                     sock_type;              //!< The type of socket SOCK_STREAM, SOCK_RAW etc...
 
        fr_event_funcs_t        active;                 //!< Active filter functions.
        fr_event_funcs_t        stored;                 //!< Stored (set, but inactive) filter functions.
 
        fr_event_error_cb_t     error;                  //!< Callback for when an error occurs on the FD.
 
        fr_event_func_map_t const *map;                 //!< Function map between #fr_event_funcs_t and kevent filters.
 
        bool                    is_registered;          //!< Whether this fr_event_fd_t's FD has been registered with
                                                        ///< kevent.  Mostly for debugging.
 
        void                    *uctx;                  //!< Context pointer to pass to each file descriptor callback.
        TALLOC_CTX              *linked_ctx;            //!< talloc ctx this event was bound to.
 
        fr_dlist_t              entry;                  //!< Entry in free list.
 
#ifndef NDEBUG
        uintptr_t               armour;                 //!< protection flag from being deleted.
#endif
 
#ifndef NDEBUG
        char const              *file;                  //!< Source file this event was last updated in.
        int                     line;                   //!< Line this event was last updated on.
#endif
};
 
struct fr_event_pid {
        fr_event_list_t         *el;                    //!< Event list this event belongs to.
 
        bool                    is_registered;          //!< Whether this user event has been registered
                                                        ///< with the event loop.
 
        pid_t                   pid;                    //!< child to wait for
        fr_event_pid_t const    **parent;
 
        fr_event_pid_cb_t       callback;               //!< callback to run when the child exits
        void                    *uctx;                  //!< Context pointer to pass to each file descriptor callback.
 
        /** Fields that are only used if we're being triggered by a user event
         */
        struct {
                fr_event_user_t         *ev;            //!< Fallback user event we use to raise a PID event when
                                                        ///< a race occurs with kevent.
                int                     status;         //!< Status we got from waitid.
        } early_exit;
#ifndef NDEBUG
        char const              *file;                  //!< Source file this event was last updated in.
        int                     line;                   //!< Line this event was last updated on.
#endif
};
 
/** Hold additional information for automatically reaped PIDs
 */
typedef struct {
        fr_event_list_t         *el;                    //!< Event list this event belongs to.
        fr_event_pid_t const    *pid_ev;                //!< pid_ev this reaper is bound to.
 
        fr_dlist_t              entry;                  //!< If the fr_event_pid is in the detached, reap state,
                                                        ///< it's inserted into a list associated with the event.
                                                        //!< We then send SIGKILL, and forcefully reap the process
                                                        ///< on exit.
 
        fr_event_pid_cb_t       callback;               //!< callback to run when the child exits
        void                    *uctx;                  //!< Context pointer to pass to each file descriptor callback.
} fr_event_pid_reap_t;
 
/** Callbacks for kevent() user events
 *
 */
struct fr_event_user_s {
        fr_event_list_t         *el;                    //!< Event list this event belongs to.
 
        bool                    is_registered;          //!< Whether this user event has been registered
                                                        ///< with the event loop.
 
        fr_event_user_cb_t      callback;               //!< The callback to call.
        void                    *uctx;                  //!< Context for the callback.
 
#ifndef NDEBUG
        char const              *file;                  //!< Source file this event was last updated in.
        int                     line;                   //!< Line this event was last updated on.
#endif
};
 
/** Callbacks to perform when the event handler is about to check the events
 *
 */
typedef struct {
        fr_dlist_t              entry;                  //!< Linked list of callback.
        fr_event_status_cb_t    callback;               //!< The callback to call.
        void                    *uctx;                  //!< Context for the callback.
} fr_event_pre_t;
 
/** Callbacks to perform after all timers and FDs have been checked
 *
 */
typedef struct {
        fr_dlist_t              entry;                  //!< Linked list of callback.
        fr_event_post_cb_t      callback;               //!< The callback to call.
        void                    *uctx;                  //!< Context for the callback.
} fr_event_post_t;
 
/** Stores all information relating to an event list
 *
 */
struct fr_event_list_s {
        struct fr_event_list_pub_s      pub;                    //!< Next event list in the chain.
        fr_rb_tree_t                    *fds;                   //!< Tree used to track FDs with filters in kqueue.
 
        int                             will_exit;              //!< Will exit on next call to fr_event_corral.
        int                             exit;                   //!< If non-zero event loop will prevent the addition
                                                                ///< of new events, and will return immediately
                                                                ///< from the corral/service function.
 
        bool                            dispatch;               //!< Whether the event list is currently dispatching events.
 
        int                             num_fd_events;          //!< Number of events in this event list.
 
        int                             kq;                     //!< instance associated with this event list.
 
        fr_dlist_head_t                 pre_callbacks;          //!< callbacks when we may be idle...
        fr_dlist_head_t                 post_callbacks;         //!< post-processing callbacks
 
        fr_dlist_head_t                 pid_to_reap;            //!< A list of all orphaned child processes we're
                                                                ///< waiting to reap.
 
        struct kevent                   events[FR_EV_BATCH_FDS]; /* so it doesn't go on the stack every time */
 
        bool                            in_handler;             //!< Deletes should be deferred until after the
                                                                ///< handlers complete.
 
        fr_dlist_head_t                 fd_to_free;             //!< File descriptor events pending deletion.
 
#ifdef WITH_EVENT_DEBUG
        fr_timer_t                      *report;                //!< Report event.
#endif
};
 
static void event_fd_func_index_build(fr_event_func_map_t *map)
{
        switch (map->idx_type) {
        default:
                return;
 
        /*
         *      - Figure out the lowest filter value
         *      - Invert it
         *      - Allocate an array
         *      - Populate the array
         */
        case FR_EVENT_FUNC_IDX_FILTER:
        {
                int                             low = 0;
                fr_event_func_map_entry_t       *entry;
 
                for (entry = map->func_to_ev; entry->name; entry++) if (entry->filter < low) low = entry->filter;
 
                map->ev_to_func = talloc_zero_array(NULL, fr_event_func_map_entry_t *, ~low + 1);
                if (unlikely(!map->ev_to_func)) abort();
 
                for (entry = map->func_to_ev; entry->name; entry++) map->ev_to_func[~entry->filter] = entry;
        }
                break;
 
        /*
         *      - Figure out the highest bit position
         *      - Allocate an array
         *      - Populate the array
         */
        case FR_EVENT_FUNC_IDX_FFLAGS:
        {
                uint8_t                         high = 0, pos;
                fr_event_func_map_entry_t       *entry;
 
                for (entry = map->func_to_ev; entry->name; entry++) {
                        pos = fr_high_bit_pos(entry->fflags);
                        if (pos > high) high = pos;
                }
 
                map->ev_to_func = talloc_zero_array(NULL, fr_event_func_map_entry_t *, high);
                if (unlikely(!map->ev_to_func)) abort();
 
                for (entry = map->func_to_ev; entry->name; entry++) {
                        typeof_field(fr_event_func_map_entry_t, fflags) fflags = entry->fflags;
 
                        /*
                         *      Multiple notes can be associated
                         *      with the same function.
                         */
                        while ((pos = fr_high_bit_pos(fflags))) {
                                pos -= 1;
                                map->ev_to_func[pos] = entry;
                                /*
                                 *      Coverity thinks that after this decrement, pos
                                 *      can be 255 even though the loop condition precludes
                                 *      it. Adding a Coverity-only check won't change that,
                                 *      so we're stuck with annotation.
                                 */
                                /* coverity[overflow_const] */
                                fflags &= ~(1 << pos);
                        }
                }
        }
                break;
        }
}
 
/** Figure out which function to call given a kevent
 *
 * This function should be called in a loop until it returns NULL.
 *
 * @param[in] ef                File descriptor state handle.
 * @param[in] filter            from the kevent.
 * @param[in,out] fflags        from the kevent.  Each call will return the function
 *                              from the next most significant NOTE_*, with each
 *                              NOTE_* before unset from fflags.
 * @return
 *      - NULL there are no more callbacks to call.
 *      - The next callback to call.
 */
static inline CC_HINT(always_inline) fr_event_fd_cb_t event_fd_func(fr_event_fd_t *ef, int *filter, int *fflags)
{
        fr_event_func_map_t const *map = ef->map;
 
#define GET_FUNC(_ef, _offset) *((fr_event_fd_cb_t const *)((uint8_t const *)&(_ef)->active + _offset))
 
        switch (map->idx_type) {
        default:
                fr_assert_fail("Invalid index type %u", map->idx_type);
                return NULL;
 
        case FR_EVENT_FUNC_IDX_FILTER:
        {
                int idx;
 
                if (!*filter) return NULL;
 
                idx = ~*filter;                         /* Consume the filter */
                *filter = 0;
 
                return GET_FUNC(ef, map->ev_to_func[idx]->offset);
        }
 
        case FR_EVENT_FUNC_IDX_FFLAGS:
        {
                int                     our_fflags = *fflags;
                uint8_t                 pos = fr_high_bit_pos(our_fflags);
 
                if (!pos) return NULL;                  /* No more fflags to consume */
                pos -= 1;                               /* Saves an array element */
 
                *fflags = our_fflags & ~(1 << pos);     /* Consume the knote */
 
                return GET_FUNC(ef, map->ev_to_func[pos]->offset);
        }
        }
}
 
/** Compare two file descriptor handles
 *
 * @param[in] one the first file descriptor handle.
 * @param[in] two the second file descriptor handle.
 * @return CMP(one, two)
 */
static int8_t fr_event_fd_cmp(void const *one, void const *two)
{
        fr_event_fd_t const     *a = one, *b = two;
 
        CMP_RETURN(a, b, fd);
 
        return CMP(a->filter, b->filter);
}
 
/** Return the number of file descriptors is_registered with this event loop
 *
 */
uint64_t fr_event_list_num_fds(fr_event_list_t *el)
{
        if (unlikely(!el)) return -1;
 
        return fr_rb_num_elements(el->fds);
}
 
/** Return the number of timer events currently scheduled
 *
 * @param[in] el to return timer events for.
 * @return number of timer events.
 */
uint64_t fr_event_list_num_timers(fr_event_list_t *el)
{
        if (unlikely(!el)) return -1;
 
        return fr_timer_list_num_events(el->pub.tl);
}
 
/** Return the kq associated with an event list.
 *
 * @param[in] el to return timer events for.
 * @return kq
 */
int fr_event_list_kq(fr_event_list_t *el)
{
        if (unlikely(!el)) return -1;
 
        return el->kq;
}
 
/** Get the current server time according to the event list
 *
 * If the event list is currently dispatching events, we return the time
 * this iteration of the event list started.
 *
 * If the event list is not currently dispatching events, we return the
 * current system time.
 *
 * @param[in]   el to get time from.
 * @return the current time according to the event list.
 */
fr_time_t fr_event_list_time(fr_event_list_t *el)
{
        return el->pub.tl->time();
}
 
/** Placeholder callback to avoid branches in service loop
 *
 * This is set in place of any NULL function pointers, so that the event loop doesn't
 * SEGV if a filter callback function is unset between corral and service.
 */
static void fr_event_fd_noop(UNUSED fr_event_list_t *el, UNUSED int fd, UNUSED int flags, UNUSED void *uctx)
{
        return;
}
 
/** Build a new evset based on function pointers present
 *
 * @note The contents of active functions may be inconsistent if this function errors.  But the
 *       only time that will occur is if the caller passed invalid arguments.
 *
 * @param[in] el                we're building events for.
 * @param[out] out_kev          where to write the evset.
 * @param[in] outlen            length of output buffer.
 * @param[out] active           The set of function pointers with active filters.
 * @param[in] ef                event to insert.
 * @param[in] new               Functions to map to filters.
 * @param[in] prev              Previous set of functions mapped to filters.
 * @return
 *      - >= 0 the number of changes written to out.
 *      - < 0 an error occurred.
 */
static ssize_t fr_event_build_evset(
#ifndef WITH_EVENT_DEBUG
                                    UNUSED
#endif
                                    fr_event_list_t *el,
                                    struct kevent out_kev[], size_t outlen, fr_event_funcs_t *active,
                                    fr_event_fd_t *ef,
                                    fr_event_funcs_t const *new, fr_event_funcs_t const *prev)
{
        struct kevent                   *out = out_kev, *end = out + outlen;
        fr_event_func_map_entry_t const *map;
        struct kevent                   add[10], *add_p = add;
        size_t                          i;
 
        EVENT_DEBUG("%p - Building new evset for FD %i (new %p, prev %p)", el, ef->fd, new, prev);
 
        /*
         *      Iterate over the function map, setting/unsetting
         *      filters and filter flags.
         */
        for (map = ef->map->func_to_ev; map->name; map++) {
                bool            has_current_func = false;
                bool            has_prev_func = false;
                uint32_t        current_fflags = 0;
                uint32_t        prev_fflags = 0;
 
                do {
                        fr_event_fd_cb_t prev_func;
                        fr_event_fd_cb_t new_func;
 
                        /*
                         *      If the previous value was the 'noop'
                         *      callback, it's identical to being unset.
                         */
                        prev_func = *(fr_event_fd_cb_t const *)((uint8_t const *)prev + map->offset);
                        if (prev_func && (prev_func != fr_event_fd_noop)) {
                                EVENT_DEBUG("\t%s prev set (%p)", map->name, prev_func);
                                prev_fflags |= map->fflags;
                                has_prev_func = true;
                        } else {
                                EVENT_DEBUG("\t%s prev unset", map->name);
                        }
 
                        new_func = *(fr_event_fd_cb_t const *)((uint8_t const *)new + map->offset);
                        if (new_func && (new_func != fr_event_fd_noop)) {
                                EVENT_DEBUG("\t%s curr set (%p)", map->name, new_func);
                                current_fflags |= map->fflags;
                                has_current_func = true;
 
                                /*
                                 *      Check the filter will work for the
                                 *      type of file descriptor specified.
                                 */
                                if (!(map->type & ef->type)) {
                                        fr_strerror_printf("kevent %s (%s), can't be applied to fd of type %s",
                                                           map->name,
                                                           fr_table_str_by_value(kevent_filter_table, map->filter, "<INVALID>"),
                                                           fr_table_str_by_value(fr_event_fd_type_table,
                                                                      map->type, "<INVALID>"));
                                        return -1;
                                }
 
                                /*
                                 *      Mark this filter function as active
                                 */
                                memcpy((uint8_t *)active + map->offset, (uint8_t const *)new + map->offset,
                                       sizeof(fr_event_fd_cb_t));
                        } else {
                                EVENT_DEBUG("\t%s curr unset", map->name);
 
                                /*
                                 *      Mark this filter function as inactive
                                 *      by setting it to the 'noop' callback.
                                 */
                                *((fr_event_fd_cb_t *)((uint8_t *)active + map->offset)) = fr_event_fd_noop;
                        }
 
                        if (!(map + 1)->coalesce) break;
                        map++;
                } while (1);
 
                if (out > end) {
                        fr_strerror_const("Out of memory to store kevent filters");
                        return -1;
                }
 
                /*
                 *      Upsert if we add a function or change the flags.
                 */
                if (has_current_func &&
                    (!has_prev_func || (current_fflags != prev_fflags))) {
                        if ((size_t)(add_p - add) >= (NUM_ELEMENTS(add))) {
                                fr_strerror_const("Out of memory to store kevent EV_ADD filters");
                                return -1;
                        }
                        EVENT_DEBUG("\tEV_SET EV_ADD filter %s (%i), flags %i, fflags %i",
                                    fr_table_str_by_value(kevent_filter_table, map->filter, "<INVALID>"),
                                    map->filter, map->flags, current_fflags);
                        EV_SET(add_p++, ef->fd, map->filter, map->flags, current_fflags, 0, ef);
 
                /*
                 *      Delete if we remove a function.
                 */
                } else if (!has_current_func && has_prev_func) {
                        EVENT_DEBUG("\tEV_SET EV_DELETE filter %s (%i), flags %i, fflags %i",
                                    fr_table_str_by_value(kevent_filter_table, map->filter, "<INVALID>"),
                                    map->filter, EV_DELETE, 0);
                        EV_SET(out++, ef->fd, map->filter, EV_DELETE, 0, 0, ef);
                }
        }
 
        /*
         *      kevent is fine with adds/deletes in the same operation
         *      on the same file descriptor, but libkqueue doesn't do
         *      any kind of coalescing or ordering so you get an EEXIST
         *      error.
         */
        for (i = 0; i < (size_t)(add_p - add); i++) memcpy(out++, &add[i], sizeof(*out));
 
        return out - out_kev;
}
 
/** Discover the type of a file descriptor
 *
 * This function writes the result of the discovery to the ef->type,
 * and ef->sock_type fields.
 *
 * @param[out] ef       to write type data to.
 * @param[in] fd        to discover the type of.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int fr_event_fd_type_set(fr_event_fd_t *ef, int fd)
{
        socklen_t       opt_len = sizeof(ef->sock_type);
 
        /*
         *      It's a socket or PCAP socket
         */
        if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &ef->sock_type, &opt_len) == 0) {
#ifdef SO_GET_FILTER
                opt_len = 0;
                if (unlikely(getsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, NULL, &opt_len) < 0)) {
                        fr_strerror_printf("Failed determining PF status: %s", fr_syserror(errno));
                        return -1;
                }
                if (opt_len) {
                        ef->type = FR_EVENT_FD_PCAP;
                } else
#endif
                {
                        ef->type = FR_EVENT_FD_SOCKET;
                }
 
        /*
         *      It's a file or directory
         */
        } else {
                struct stat buf;
 
                if (errno != ENOTSOCK) {
                        fr_strerror_printf("Failed retrieving socket type: %s", fr_syserror(errno));
                        return -1;
                }
 
                if (fstat(fd, &buf) < 0) {
                        fr_strerror_printf("Failed calling stat() on file: %s", fr_syserror(errno));
                        return -1;
                }
 
                if (S_ISDIR(buf.st_mode)) {
                        ef->type = FR_EVENT_FD_DIRECTORY;
                } else {
                        ef->type = FR_EVENT_FD_FILE;
                }
        }
        ef->fd = fd;
 
        return 0;
}
 
/** Remove a file descriptor from the event loop and rbtree but don't explicitly free it
 *
 *
 * @param[in] ef        to remove.
 * @return
 *      - 0 on success.
 *      - -1 on error;
 */
static int _event_fd_delete(fr_event_fd_t *ef)
{
        struct kevent           evset[10];
        int                     count = 0;
        fr_event_list_t         *el = ef->el;
        fr_event_funcs_t        funcs;
 
        /*
         *      Already been removed from the various trees and
         *      the event loop.
         */
        if (ef->is_registered) {
                memset(&funcs, 0, sizeof(funcs));
 
                fr_assert(ef->armour == 0);
 
                /*
                 *      If this fails, it's a pretty catastrophic error.
                 */
                count = fr_event_build_evset(el, evset, sizeof(evset)/sizeof(*evset),
                                             &ef->active, ef, &funcs, &ef->active);
                if (count > 0) {
                        int ret;
 
                        /*
                         *      If this fails, assert on debug builds.
                         */
                        ret = kevent(el->kq, evset, count, NULL, 0, NULL);
                        if (!fr_cond_assert_msg(ret >= 0,
                                                "FD %i was closed without being removed from the KQ: %s",
                                                ef->fd, fr_syserror(errno))) {
                                return -1;      /* Prevent the free, and leave the fd in the trees */
                        }
                }
 
                fr_rb_delete(el->fds, ef);
                ef->is_registered = false;
        }
 
        /*
         *      Insert into the deferred free list, event will be
         *      freed later.
         */
        if (el->in_handler) {
                /*
                 *      Don't allow the same event to be
                 *      inserted into the free list multiple
                 *      times.
                 *
                 *      This can happen if the same ef is
                 *      delivered by multiple filters, i.e.
                 *      if EVFILT_READ and EVFILT_WRITE
                 *      were both high, and both handlers
                 *      attempted to delete the event
                 *      we'd need to prevent the event being
                 *      inserted into the free list multiple
                 *      times.
                 */
                if (!fr_dlist_entry_in_list(&ef->entry)) fr_dlist_insert_tail(&el->fd_to_free, ef);
                return -1;                              /* Will be freed later */
        } else if (fr_dlist_entry_in_list(&ef->entry)) {
                fr_dlist_remove(&el->fd_to_free, ef);
        }
 
        return 0;
}
 
/** Move a file descriptor event from one event list to another
 *
 * FIXME - Move suspended events too.
 *
 * @note Any pending events will not be transferred.
 *
 * @param[in] dst       Event list to move file descriptor event to.
 * @param[in] src       Event list to move file descriptor from.
 * @param[in] fd        of the event to move.
 * @param[in] filter    of the event to move.
 * @return
 *      - 0 on success.
 *      - -1 on failure.  The event will remain active in the src list.
 */
int _fr_event_fd_move(NDEBUG_LOCATION_ARGS
                      fr_event_list_t *dst, fr_event_list_t *src, int fd, fr_event_filter_t filter)
{
        fr_event_fd_t   *ef;
        int             ret;
 
        if (fr_event_loop_exiting(dst)) {
                fr_strerror_const("Destination event loop exiting");
                return -1;
        }
 
        /*
         *      Ensure this exists
         */
        ef = fr_rb_find(src->fds, &(fr_event_fd_t){ .fd = fd, .filter = filter });
        if (unlikely(!ef)) {
                fr_strerror_printf("No events are registered for fd %i", fd);
                return -1;
        }
 
        ret = _fr_event_filter_insert(NDEBUG_LOCATION_VALS
                                      ef->linked_ctx, NULL,
                                      dst, ef->fd, ef->filter, &ef->active, ef->error, ef->uctx);
        if (ret < 0) return -1;
 
        (void)fr_event_fd_delete(src, ef->fd, ef->filter);
 
        return ret;
}
 
 
/** Suspend/resume a subset of filters
 *
 * This function trades producing useful errors for speed.
 *
 * An example of suspending the read filter for an FD would be:
 @code {.c}
   static fr_event_update_t pause_read[] = {
        FR_EVENT_SUSPEND(fr_event_io_func_t, read),
        { 0 }
   }
 
   fr_event_filter_update(el, fd, FR_EVENT_FILTER_IO, pause_read);
 @endcode
 *
 * @param[in] el        to update descriptor in.
 * @param[in] fd        to update filters for.
 * @param[in] filter    The type of filter to update.
 * @param[in] updates   An array of updates to toggle filters on/off without removing
 *                      the callback function.
 */
int _fr_event_filter_update(NDEBUG_LOCATION_ARGS
                            fr_event_list_t *el, int fd, fr_event_filter_t filter, fr_event_update_t const updates[])
{
        fr_event_fd_t           *ef;
        size_t                  i;
        fr_event_funcs_t        curr_active, curr_stored;
        struct kevent           evset[10];
        int                     count = 0;
 
        ef = fr_rb_find(el->fds, &(fr_event_fd_t){ .fd = fd, .filter = filter });
        if (unlikely(!ef)) {
                fr_strerror_printf("No events are registered for fd %i", fd);
                return -1;
        }
 
#ifndef NDEBUG
        ef->file = file;
        ef->line = line;
#endif
 
        /*
         *      Cheapest way of ensuring this function can error without
         *      leaving everything in an inconsistent state.
         */
        memcpy(&curr_active, &ef->active, sizeof(curr_active));
        memcpy(&curr_stored, &ef->stored, sizeof(curr_stored));
 
        /*
         *      Apply modifications to our copies of the active/stored array.
         */
        for (i = 0; updates[i].op; i++) {
                switch (updates[i].op) {
                default:
                case FR_EVENT_OP_SUSPEND:
                        fr_assert(ef->armour == 0); /* can't suspect protected FDs */
                        memcpy((uint8_t *)&ef->stored + updates[i].offset,
                               (uint8_t *)&ef->active + updates[i].offset, sizeof(fr_event_fd_cb_t));
                        memset((uint8_t *)&ef->active + updates[i].offset, 0, sizeof(fr_event_fd_cb_t));
                        break;
 
                case FR_EVENT_OP_RESUME:
                        memcpy((uint8_t *)&ef->active + updates[i].offset,
                               (uint8_t *)&ef->stored + updates[i].offset, sizeof(fr_event_fd_cb_t));
                        memset((uint8_t *)&ef->stored + updates[i].offset, 0, sizeof(fr_event_fd_cb_t));
                        break;
                }
        }
 
        count = fr_event_build_evset(el, evset, sizeof(evset)/sizeof(*evset), &ef->active,
                                     ef, &ef->active, &curr_active);
        if (unlikely(count < 0)) {
        error:
                memcpy(&ef->active, &curr_active, sizeof(curr_active));
                memcpy(&ef->stored, &curr_stored, sizeof(curr_stored));
                return -1;
        }
 
        if (count && unlikely(kevent(el->kq, evset, count, NULL, 0, NULL) < 0)) {
                fr_strerror_printf("Failed updating filters for FD %i: %s", ef->fd, fr_syserror(errno));
                goto error;
        }
 
        return 0;
}
 
/** Insert a filter for the specified fd
 *
 * @param[in] ctx       to bind lifetime of the event to.
 * @param[out] ef_out   Previously allocated ef, or NULL.
 * @param[in] el        to insert fd callback into.
 * @param[in] fd        to install filters for.
 * @param[in] filter    one of the #fr_event_filter_t values.
 * @param[in] funcs     Structure containing callback functions. If a function pointer
 *                      is set, the equivalent kevent filter will be installed.
 * @param[in] error     function to call when an error occurs on the fd.
 * @param[in] uctx      to pass to handler.
 */
int _fr_event_filter_insert(NDEBUG_LOCATION_ARGS
                            TALLOC_CTX *ctx, fr_event_fd_t **ef_out,
                            fr_event_list_t *el, int fd,
                            fr_event_filter_t filter,
                            void *funcs, fr_event_error_cb_t error,
                            void *uctx)
{
        ssize_t                 count;
        fr_event_fd_t           *ef;
        fr_event_funcs_t        active;
        struct kevent           evset[10];
 
        if (unlikely(!el)) {
                fr_strerror_const("Invalid argument: NULL event list");
                return -1;
        }
 
        if (unlikely(fd < 0)) {
                fr_strerror_printf("Invalid arguments: Bad FD %i", fd);
                return -1;
        }
 
        if (unlikely(el->exit)) {
                fr_strerror_const("Event loop exiting");
                return -1;
        }
 
        if (!ef_out || !*ef_out) {
                ef = fr_rb_find(el->fds, &(fr_event_fd_t){ .fd = fd, .filter = filter });
        } else {
                ef = *ef_out;
                fr_assert((fd < 0) || (ef->fd == fd));
        }
 
        /*
         *      Need to free the event to change the talloc link.
         *
         *      This is generally bad.  If you hit this
         *      code path you probably screwed up somewhere.
         */
        if (unlikely(ef && (ef->linked_ctx != ctx))) TALLOC_FREE(ef);
 
        /*
         *      No pre-existing event.  Allocate an entry
         *      for insertion into the rbtree.
         */
        if (!ef) {
                ef = talloc_zero(el, fr_event_fd_t);
                if (unlikely(!ef)) {
                        fr_strerror_const("Out of memory");
                        return -1;
                }
                talloc_set_destructor(ef, _event_fd_delete);
 
                /*
                 *      Bind the lifetime of the event to the specified
                 *      talloc ctx.  If the talloc ctx is freed, the
                 *      event will also be freed.
                 */
                if (ctx != el) talloc_link_ctx(ctx, ef);
                ef->linked_ctx = ctx;
                ef->el = el;
 
                /*
                 *      Determine what type of file descriptor
                 *      this is.
                 */
                if (fr_event_fd_type_set(ef, fd) < 0) {
                free:
                        talloc_free(ef);
                        return -1;
                }
 
                /*
                 *      Check the filter value is valid
                 */
                if ((filter > (NUM_ELEMENTS(filter_maps) - 1))) {
                not_supported:
                        fr_strerror_printf("Filter %u not supported", filter);
                        goto free;
                }
                ef->map = &filter_maps[filter];
                if (ef->map->idx_type == FR_EVENT_FUNC_IDX_NONE) goto not_supported;
 
                count = fr_event_build_evset(el, evset, sizeof(evset)/sizeof(*evset),
                                             &ef->active, ef, funcs, &ef->active);
                if (count < 0) goto free;
                if (count && (unlikely(kevent(el->kq, evset, count, NULL, 0, NULL) < 0))) {
                        fr_strerror_printf("Failed inserting filters for FD %i: %s", fd, fr_syserror(errno));
                        goto free;
                }
 
                ef->filter = filter;
                fr_rb_insert(el->fds, ef);
                ef->is_registered = true;
 
        /*
         *      Pre-existing event, update the filters and
         *      functions associated with the file descriptor.
         */
        } else {
                fr_assert(ef->is_registered == true);
 
                /*
                 *      Take a copy of the current set of active
                 *      functions, so we can error out in a
                 *      consistent state.
                 */
                memcpy(&active, &ef->active, sizeof(ef->active));
 
                fr_assert((ef->armour == 0) || ef->active.io.read);
 
                count = fr_event_build_evset(el, evset, sizeof(evset)/sizeof(*evset),
                                             &ef->active, ef, funcs, &ef->active);
                if (count < 0) {
                error:
                        memcpy(&ef->active, &active, sizeof(ef->active));
                        return -1;
                }
                if (count && (unlikely(kevent(el->kq, evset, count, NULL, 0, NULL) < 0))) {
                        fr_strerror_printf("Failed modifying filters for FD %i: %s", fd, fr_syserror(errno));
                        goto error;
                }
 
                /*
                 *      Clear any previously suspended functions
                 */
                memset(&ef->stored, 0, sizeof(ef->stored));
        }
 
#ifndef NDEBUG
        ef->file = file;
        ef->line = line;
#endif
        ef->error = error;
        ef->uctx = uctx;
 
        if (ef_out) *ef_out = ef;
 
        return 0;
}
 
/** Associate I/O callbacks with a file descriptor
 *
 * @param[in] ctx       to bind lifetime of the event to.
 * @param[out] ef_out   Where to store the output event
 * @param[in] el        to insert fd callback into.
 * @param[in] fd        to install filters for.
 * @param[in] read_fn   function to call when fd is readable.
 * @param[in] write_fn  function to call when fd is writable.
 * @param[in] error     function to call when an error occurs on the fd.
 * @param[in] uctx      to pass to handler.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int _fr_event_fd_insert(NDEBUG_LOCATION_ARGS
                        TALLOC_CTX *ctx, fr_event_fd_t **ef_out, fr_event_list_t *el, int fd,
                        fr_event_fd_cb_t read_fn,
                        fr_event_fd_cb_t write_fn,
                        fr_event_error_cb_t error,
                        void *uctx)
{
        fr_event_io_func_t funcs =  { .read = read_fn, .write = write_fn };
 
        if (unlikely(!read_fn && !write_fn)) {
                fr_strerror_const("Invalid arguments: All callbacks are NULL");
                return -1;
        }
 
        return _fr_event_filter_insert(NDEBUG_LOCATION_VALS
                                       ctx, ef_out, el, fd, FR_EVENT_FILTER_IO, &funcs, error, uctx);
}
 
/** Remove a file descriptor from the event loop
 *
 * @param[in] el        to remove file descriptor from.
 * @param[in] fd        to remove.
 * @param[in] filter    The type of filter to remove.
 * @return
 *      - 0 if file descriptor was removed.
 *      - <0 on error.
 */
int fr_event_fd_delete(fr_event_list_t *el, int fd, fr_event_filter_t filter)
{
        fr_event_fd_t   *ef;
 
        ef = fr_rb_find(el->fds, &(fr_event_fd_t){ .fd = fd, .filter = filter });
        if (unlikely(!ef)) {
                fr_strerror_printf("No events are registered for fd %d, filter %u", fd, filter);
                return -1;
        }
 
        /*
         *      Free will normally fail if it's
         *      a deferred free. There is a special
         *      case for kevent failures though.
         *
         *      We distinguish between the two by
         *      looking to see if the ef is still
         *      in the even tree.
         *
         *      Talloc returning -1 guarantees the
         *      memory has not been freed.
         */
        if ((talloc_free(ef) == -1) && ef->is_registered) return -1;
 
        return 0;
}
 
/** Get the opaque event handle from a file descriptor
 *
 * @param[in] el        to search for fd/filter in.
 * @param[in] fd        to search for.
 * @param[in] filter    to search for.
 * @return
 *      - NULL if no event could be found.
 *      - The opaque handle representing an fd event.
 */
fr_event_fd_t *fr_event_fd_handle(fr_event_list_t *el, int fd, fr_event_filter_t filter)
{
        fr_event_fd_t *ef;
 
        ef = fr_rb_find(el->fds, &(fr_event_fd_t){ .fd = fd, .filter = filter });
        if (unlikely(!ef)) {
                fr_strerror_printf("No events are registered for fd %i", fd);
                return NULL;
        }
 
        return ef;
}
 
/** Returns the appropriate callback function for a given event
 *
 * @param[in] ef        the event filter fd handle.
 * @param[in] kq_filter If the callbacks are indexed by filter.
 * @param[in] kq_fflags If the callbacks are indexed by NOTES (fflags).
 * @return
 *      - NULL if no event it associated with the given ef/kq_filter or kq_fflags combo.
 *      - The callback that would be called if an event with this filter/fflag combo was received.
 */
fr_event_fd_cb_t fr_event_fd_cb(fr_event_fd_t *ef, int kq_filter, int kq_fflags)
{
        return event_fd_func(ef, &kq_filter, &kq_fflags);
}
 
/** Returns the uctx associated with an fr_event_fd_t handle
 *
 */
void *fr_event_fd_uctx(fr_event_fd_t *ef)
{
        return ef->uctx;
}
 
#ifndef NDEBUG
/** Armour an FD
 *
 * @param[in] el        to remove file descriptor from.
 * @param[in] fd        to remove.
 * @param[in] filter    The type of filter to remove.
 * @param[in] armour    The armour to add.
 * @return
 *      - 0 if file descriptor was armoured
 *      - <0 on error.
 */
int fr_event_fd_armour(fr_event_list_t *el, int fd, fr_event_filter_t filter, uintptr_t armour)
{
        fr_event_fd_t   *ef;
 
        ef = fr_rb_find(el->fds, &(fr_event_fd_t){ .fd = fd, .filter = filter });
        if (unlikely(!ef)) {
                fr_strerror_printf("No events are registered for fd %i", fd);
                return -1;
        }
 
        if (ef->armour != 0) {
                fr_strerror_printf("FD %i is already armoured", fd);
                return -1;
        }
 
        ef->armour = armour;
 
        return 0;
}
 
/** Unarmour an FD
 *
 * @param[in] el        to remove file descriptor from.
 * @param[in] fd        to remove.
 * @param[in] filter    The type of filter to remove.
 * @param[in] armour    The armour to remove
 * @return
 *      - 0 if file descriptor was unarmoured
 *      - <0 on error.
 */
int fr_event_fd_unarmour(fr_event_list_t *el, int fd, fr_event_filter_t filter, uintptr_t armour)
{
        fr_event_fd_t   *ef;
 
        ef = fr_rb_find(el->fds, &(fr_event_fd_t){ .fd = fd, .filter = filter });
        if (unlikely(!ef)) {
                fr_strerror_printf("No events are registered for fd %i", fd);
                return -1;
        }
 
        fr_assert(ef->armour == armour);
 
        ef->armour = 0;
        return 0;
}
#endif
 
/** Remove PID wait event from kevent if the fr_event_pid_t is freed
 *
 * @param[in] ev        to free.
 * @return 0
 */
static int _event_pid_free(fr_event_pid_t *ev)
{
        struct kevent evset;
 
        if (ev->parent) *ev->parent = NULL;
        if (!ev->is_registered || (ev->pid < 0)) return 0; /* already deleted from kevent */
 
        EVENT_DEBUG("%p - Disabling event for PID %u - %p was freed", ev->el, (unsigned int)ev->pid, ev);
 
        EV_SET(&evset, ev->pid, EVFILT_PROC, EV_DELETE, NOTE_EXIT, 0, ev);
 
        (void) kevent(ev->el->kq, &evset, 1, NULL, 0, NULL);
 
        return 0;
}
 
/** Evaluate a EVFILT_PROC event
 *
 */
CC_NO_UBSAN(function) /* UBSAN: false positive - Public/private version of fr_event_list_t trips -fsanitize=function */
static inline CC_HINT(always_inline)
void event_pid_eval(fr_event_list_t *el, struct kevent *kev)
{
        pid_t                   pid;
        fr_event_pid_t          *ev;
        fr_event_pid_cb_t       callback;
        void                    *uctx;
 
        EVENT_DEBUG("%p - PID %u exited with status %i",
                    el, (unsigned int)kev->ident, (unsigned int)kev->data);
 
        ev = talloc_get_type_abort((void *)kev->udata, fr_event_pid_t);
 
        fr_assert(ev->pid == (pid_t) kev->ident);
        fr_assert((kev->fflags & NOTE_EXIT) != 0);
 
        pid = ev->pid;
        callback = ev->callback;
        uctx = ev->uctx;
 
        ev->is_registered = false;      /* so we won't hit kevent again when it's freed */
 
        /*
         *      Delete the event before calling it.
         *
         *      This also sets the parent pointer
         *      to NULL, so the thing that started
         *      monitoring the process knows the
         *      handle is no longer valid.
         *
         *      EVFILT_PROC NOTE_EXIT events are always
         *      oneshot no matter what flags we pass,
         *      so we're just reflecting the state of
         *      the kqueue.
         */
        talloc_free(ev);
 
        if (callback) callback(el, pid, (int) kev->data, uctx);
}
 
/** Called on the next loop through the event loop when inserting an EVFILT_PROC event fails
 *
 * This is just a trampoleen function which takes the user event and simulates
 * an EVFILT_PROC event from it.
 *
 * @param[in] el        That received the event.
 * @param[in] uctx      An fr_event_pid_t to process.
 */
static void _fr_event_pid_early_exit(fr_event_list_t *el, void *uctx)
{
        fr_event_pid_t *ev = talloc_get_type_abort(uctx, fr_event_pid_t);
 
        EVENT_DEBUG("%p - PID %ld exited early, triggered through user event", el, (long)ev->pid);
 
        /*
         *      Simulate a real struct kevent with the values we
         *      recorded in fr_event_pid_wait.
         */
        event_pid_eval(el, &(struct kevent){ .ident = ev->pid, .data = ev->early_exit.status, .fflags = NOTE_EXIT, .udata = ev });
}
 
/** Insert a PID event into an event list
 *
 * @note The talloc parent of the memory returned in ev_p must not be changed.
 *       If the lifetime of the event needs to be bound to another context
 *       this function should be called with the existing event pointed to by
 *       ev_p.
 *
 * @param[in] ctx               to bind lifetime of the event to.
 * @param[in] el                to insert event into.
 * @param[in,out] ev_p          If not NULL modify this event instead of creating a new one.  This is a parent
 *                              in a temporal sense, not in a memory structure or dependency sense.
 * @param[in] pid               child PID to wait for
 * @param[in] callback          function to execute if the event fires.
 * @param[in] uctx              user data to pass to the event.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int _fr_event_pid_wait(NDEBUG_LOCATION_ARGS
                       TALLOC_CTX *ctx, fr_event_list_t *el, fr_event_pid_t const **ev_p,
                       pid_t pid, fr_event_pid_cb_t callback, void *uctx)
{
        fr_event_pid_t *ev;
        struct kevent evset;
 
        ev = talloc(ctx, fr_event_pid_t);
        if (unlikely(ev == NULL)) {
                fr_strerror_const("Out of memory");
                return -1;
        }
        *ev = (fr_event_pid_t) {
                .el = el,
                .pid = pid,
                .callback = callback,
                .uctx = uctx,
                .parent = ev_p,
#ifndef NDEBUG
                .file = file,
                .line = line,
#endif
        };
        talloc_set_destructor(ev, _event_pid_free);
 
        /*
         *      macOS only, on FreeBSD NOTE_EXIT always provides
         *      the status anyway.
         */
#ifndef NOTE_EXITSTATUS
#define NOTE_EXITSTATUS (0)
#endif
 
        EVENT_DEBUG("%p - Adding exit waiter for PID %u", el, (unsigned int)pid);
 
        EV_SET(&evset, pid, EVFILT_PROC, EV_ADD | EV_ONESHOT, NOTE_EXIT | NOTE_EXITSTATUS, 0, ev);
        ev->is_registered = true;
 
        /*
         *      This deals with the race where the process exited
         *      before we could add it to the kqueue.
         *
         *      Unless our caller is broken, the process should
         *      still be available for reaping, so we check
         *      waitid to see if there is a pending process and
         *      then call the callback as kqueue would have done.
         */
        if (unlikely(kevent(el->kq, &evset, 1, NULL, 0, NULL) < 0)) {
                siginfo_t       info;
                int ret;
 
                /*
                 *      Ensure we don't accidentally pick up the error
                 *      from kevent.
                 */
                fr_strerror_clear();
 
                ev->is_registered = false;
 
                /*
                 *      If the child exited before kevent() was
                 *      called, we need to get its status via
                 *      waitid().
                 *
                 *      We don't reap the process here to emulate
                 *      what kqueue does (notify but not reap).
                 *
                 *      waitid returns >0 on success, 0 if the
                 *      process is still running, and -1 on failure.
                 *
                 *      If we get a 0, then that's extremely strange
                 *      as adding the kevent failed for a reason
                 *      other than the process already having exited.
                 *
                 *      On Linux waitid will always return 1 to
                 *      indicate the process exited.
                 *
                 *      On macOS we seem to get a mix of 1 or 0,
                 *      even if the si_code is one of the values
                 *      we'd consider to indicate that the process
                 *      had completed.
                 */
                ret = waitid(P_PID, pid, &info, WEXITED | WNOHANG | WNOWAIT);
                if (ret > 0) {
                        static fr_table_num_sorted_t const si_codes[] = {
                                { L("exited"),  CLD_EXITED },
                                { L("killed"),  CLD_KILLED },
                                { L("dumped"),  CLD_DUMPED },
                                { L("trapped"), CLD_TRAPPED },
                                { L("stopped"), CLD_STOPPED },
                                { L("continued"), CLD_CONTINUED }
                        };
                        static size_t si_codes_len = NUM_ELEMENTS(si_codes);
 
                        switch (info.si_code) {
                        case CLD_EXITED:
                        case CLD_KILLED:
                        case CLD_DUMPED:
                                EVENT_DEBUG("%p - PID %ld early exit - code %s (%d), status %d",
                                            el, (long)pid, fr_table_str_by_value(si_codes, info.si_code, "<UNKOWN>"),
                                            info.si_code, info.si_status);
 
                                /*
                                 *      Record the status for later
                                 */
                                ev->early_exit.status = info.si_status;
 
                                /*
                                 *      The user event acts as a surrogate for
                                 *      an EVFILT_PROC event, and will be evaluated
                                 *      during the next loop through the event loop.
                                 *
                                 *      It will be automatically deleted when the
                                 *      fr_event_pid_t is freed.
                                 *
                                 *      Previously we tried to evaluate the proc
                                 *      callback here directly, but this lead to
                                 *      multiple problems, the biggest being that
                                 *      setting requests back to resumable failed
                                 *      because they were not yet yielded,
                                 *      leading to hangs.
                                 */
                        early_exit:
                                if (fr_event_user_insert(ev, el, &ev->early_exit.ev, true, _fr_event_pid_early_exit, ev) < 0) {
                                        fr_strerror_printf_push("Failed adding wait for PID %ld, and failed adding "
                                                                "backup user event", (long) pid);
                                error:
                                        talloc_free(ev);
                                        return -1;
                                }
                                break;
 
                        default:
                                fr_strerror_printf("Unexpected code %s (%d) whilst waiting on PID %ld",
                                                   fr_table_str_by_value(si_codes, info.si_code, "<UNKOWN>"),
                                                   info.si_code, (long) pid);
 
                                goto error;
                        }
                /*
                 *      Failed adding waiter for process, but process has not completed...
                 *
                 *      This weird, but seems to happen on macOS occasionally.
                 *
                 *      Add an event to run early exit...
                 *
                 *      Man pages for waitid say if it returns 0 the info struct can be in
                 *      a nondeterministic state, so there's nothing more to do.
                 */
                } else if (ret == 0) {
                        goto early_exit;
                } else {
                        /*
                        *       Print this error here, so that the caller gets
                        *       the error from kevent(), and not waitpid().
                        */
                        fr_strerror_printf("Failed adding waiter for PID %ld - kevent %s, waitid %s",
                                           (long) pid, fr_syserror(evset.flags), fr_syserror(errno));
 
                        goto error;
                }
        }
 
        /*
         *      Sometimes the caller doesn't care about getting the
         *      PID.  But we still want to clean it up.
         */
        if (ev_p) *ev_p = ev;
 
        return 0;
}
 
/** Saves some boilerplate...
 *
 */
static inline CC_HINT(always_inline)
void event_list_reap_run_callback(fr_event_pid_reap_t *reap, pid_t pid, int status)
{
        if (reap->callback) reap->callback(reap->el, pid, status, reap->uctx);
}
 
/** Does the actual reaping of PIDs
 *
 */
static void _fr_event_pid_reap_cb(UNUSED fr_event_list_t *el, pid_t pid, int status, void *uctx)
{
        fr_event_pid_reap_t     *reap = talloc_get_type_abort(uctx, fr_event_pid_reap_t);
 
        waitpid(pid, &status, WNOHANG); /* Don't block the process if there's a logic error somewhere */
 
        EVENT_DEBUG("%s - Reaper reaped PID %u, status %u - %p", __FUNCTION__, pid, status, reap);
 
        event_list_reap_run_callback(reap, pid, status);
 
        talloc_free(reap);
}
 
static int _fr_event_reap_free(fr_event_pid_reap_t *reap)
{
        /*
         *      Clear out the entry in the pid_to_reap
         *      list if the event was inserted.
         */
        if (fr_dlist_entry_in_list(&reap->entry)) {
                EVENT_DEBUG("%s - Removing entry from pid_to_reap %i - %p", __FUNCTION__,
                            reap->pid_ev ? reap->pid_ev->pid : -1, reap);
                fr_dlist_remove(&reap->el->pid_to_reap, reap);
        }
 
        return 0;
}
 
/** Asynchronously wait for a PID to exit, then reap it
 *
 * This is intended to be used when we no longer care about a process
 * exiting, but we still want to clean up its state so we don't have
 * zombie processes sticking around.
 *
 * @param[in] el                to use to reap the process.
 * @param[in] pid               to reap.
 * @param[in] callback          to call when the process is reaped.
 *                              May be NULL.
 * @param[in] uctx              to pass to callback.
 * @return
 *      - -1 if we couldn't find the process or it has already exited/been reaped.
 *      - 0 on success (we setup a process handler).
 */
int _fr_event_pid_reap(NDEBUG_LOCATION_ARGS fr_event_list_t *el, pid_t pid, fr_event_pid_cb_t callback, void *uctx)
{
        int                     ret;
        fr_event_pid_reap_t     *reap;
 
        reap = talloc_zero(NULL, fr_event_pid_reap_t);
        if (unlikely(!reap)) {
                fr_strerror_const("Out of memory");
                return -1;
        }
        talloc_set_destructor(reap, _fr_event_reap_free);
 
        ret = _fr_event_pid_wait(NDEBUG_LOCATION_VALS reap, el, &reap->pid_ev, pid, _fr_event_pid_reap_cb, reap);
        if (ret < 0) {
                talloc_free(reap);
                return ret;
        }
 
        reap->el = el;
        reap->callback = callback;
        reap->uctx = uctx;
 
        EVENT_DEBUG("%s - Adding reaper for PID %u - %p", __FUNCTION__, pid, reap);
 
        fr_dlist_insert_tail(&el->pid_to_reap, reap);
 
        return ret;
}
 
/** Send a signal to all the processes we have in our reap list, and reap them
 *
 * @param[in] el        containing the processes to reap.
 * @param[in] timeout   how long to wait before we signal the processes.
 * @param[in] signal    to send to processes.  Should be a fatal signal.
 * @return The number of processes reaped.
 */
unsigned int fr_event_list_reap_signal(fr_event_list_t *el, fr_time_delta_t timeout, int signal)
{
        unsigned int processed = fr_dlist_num_elements(&el->pid_to_reap);
        fr_event_pid_reap_t *reap = NULL;
 
        /*
         *      If we've got a timeout, our best option
         *      is to use a kqueue instance to monitor
         *      for process exit.
         */
        if (fr_time_delta_ispos(timeout) && fr_dlist_num_elements(&el->pid_to_reap)) {
                int             status;
                struct kevent   evset;
                int             waiting = 0;
                int             kq = kqueue();
                fr_time_t       now, start = el->pub.tl->time(), end = fr_time_add(start, timeout);
 
                if (unlikely(kq < 0)) goto force;
 
                fr_dlist_foreach_safe(&el->pid_to_reap, fr_event_pid_reap_t, i) {
                        if (!i->pid_ev) {
                                EVENT_DEBUG("%p - %s - Reaper already called (logic error)... - %p",
                                            el, __FUNCTION__, i);
 
                                event_list_reap_run_callback(i, -1, SIGKILL);
                                talloc_free(i);
                                continue;
                        }
 
                        /*
                         *      See if any processes have exited already
                         */
                        if (waitpid(i->pid_ev->pid, &status, WNOHANG) == i->pid_ev->pid) { /* reap */
                                EVENT_DEBUG("%p - %s - Reaper PID %u already exited - %p",
                                            el, __FUNCTION__, i->pid_ev->pid, i);
                                event_list_reap_run_callback(i, i->pid_ev->pid, SIGKILL);
                                talloc_free(i);
                                continue;
                        }
 
                        /*
                         *      Add the rest to a temporary event loop
                         */
                        EV_SET(&evset, i->pid_ev->pid, EVFILT_PROC, EV_ADD, NOTE_EXIT, 0, i);
                        if (kevent(kq, &evset, 1, NULL, 0, NULL) < 0) {
                                EVENT_DEBUG("%p - %s - Failed adding reaper PID %u to tmp event loop - %p",
                                            el, __FUNCTION__, i->pid_ev->pid, i);
                                event_list_reap_run_callback(i, i->pid_ev->pid, SIGKILL);
                                talloc_free(i);
                                continue;
                        }
                        waiting++;
                }}
 
                /*
                 *      Keep draining process exits as they come in...
                 */
                while ((waiting > 0) && fr_time_gt(end, (now = el->pub.tl->time()))) {
                        struct kevent   kev;
                        int             ret;
 
                        ret = kevent(kq, NULL, 0, &kev, 1, &fr_time_delta_to_timespec(fr_time_sub(end, now)));
                        switch (ret) {
                        default:
                                EVENT_DEBUG("%p - %s - Reaper tmp loop error %s, forcing process reaping",
                                            el, __FUNCTION__, fr_syserror(errno));
                                close(kq);
                                goto force;
 
                        case 0:
                                EVENT_DEBUG("%p - %s - Reaper timeout waiting for process exit, forcing process reaping",
                                            el, __FUNCTION__);
                                close(kq);
                                goto force;
 
                        case 1:
                                reap = talloc_get_type_abort(kev.udata, fr_event_pid_reap_t);
 
                                EVENT_DEBUG("%p - %s - Reaper reaped PID %u, status %u - %p",
                                            el, __FUNCTION__, (unsigned int)kev.ident, (unsigned int)kev.data, reap);
                                waitpid(reap->pid_ev->pid, &status, WNOHANG);   /* reap */
 
                                event_list_reap_run_callback(reap, reap->pid_ev->pid, status);
                                talloc_free(reap);
                                break;
                        }
                        waiting--;
                }
 
                close(kq);
        }
 
force:
        /*
         *      Deal with any lingering reap requests
         */
        while ((reap = fr_dlist_head(&el->pid_to_reap))) {
                int status;
 
                EVENT_DEBUG("%s - Reaper forcefully reaping PID %u - %p", __FUNCTION__, reap->pid_ev->pid, reap);
 
                if (kill(reap->pid_ev->pid, signal) < 0) {
                        /*
                         *      Make sure we don't hang if the
                         *      process has actually exited.
                         *
                         *      We could check for ESRCH but it's
                         *      not clear if that'd be returned
                         *      for a PID in the unreaped state
                         *      or not...
                         */
                        waitpid(reap->pid_ev->pid, &status, WNOHANG);
                        event_list_reap_run_callback(reap, reap->pid_ev->pid, status);
                        talloc_free(reap);
                        continue;
                }
 
                /*
                 *      Wait until the child process exits
                 */
                waitpid(reap->pid_ev->pid, &status, 0);
                event_list_reap_run_callback(reap, reap->pid_ev->pid, status);
                talloc_free(reap);
        }
 
        return processed;
}
 
/** Memory will not be freed if we fail to remove the event from the kqueue
 *
 * It's easier to debug memory leaks with modern tooling than it is
 * to determine why we get random failures and event leaks inside of kqueue.
 *
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int _event_user_delete(fr_event_user_t *ev)
{
        if (ev->is_registered) {
                struct kevent evset;
 
                EV_SET(&evset, (uintptr_t)ev, EVFILT_USER, EV_DELETE, 0, 0, 0);
 
                if (unlikely(kevent(ev->el->kq, &evset, 1, NULL, 0, NULL) < 0)) {
                        fr_strerror_printf("Failed removing user event - kevent %s", fr_syserror(evset.flags));
                        return -1;
                }
                ev->is_registered = false;
        }
 
        return 0;
}
 
static inline CC_HINT(always_inline)
void event_user_eval(fr_event_list_t *el, struct kevent *kev)
{
        fr_event_user_t *ev;
 
        /*
         *      This is just a "wakeup" event, which
         *      is always ignored.
         */
        if (kev->ident == 0) return;
 
        ev = talloc_get_type_abort((void *)kev->ident, fr_event_user_t);
        fr_assert((uintptr_t)ev == kev->ident);
 
        ev->callback(el, ev->uctx);
}
 
/** Add a user callback to the event list.
 *
 * @param[in] ctx       to allocate the event in.
 * @param[in] el        Containing the timer events.
 * @param[out] ev_p     Where to write a pointer.
 * @param[in] trigger   Whether the user event is triggered initially.
 * @param[in] callback  for EVFILT_USER.
 * @param[in] uctx      for the callback.
 * @return
 *      - 0 on success.
 *      - -1 on error.
 */
int _fr_event_user_insert(NDEBUG_LOCATION_ARGS
                          TALLOC_CTX *ctx, fr_event_list_t *el, fr_event_user_t **ev_p,
                          bool trigger, fr_event_user_cb_t callback, void *uctx)
{
        fr_event_user_t *ev;
        struct kevent evset;
 
        ev = talloc(ctx, fr_event_user_t);
        if (unlikely(ev == NULL)) {
                fr_strerror_const("Out of memory");
                return -1;
        }
        *ev = (fr_event_user_t) {
                .el = el,
                .callback = callback,
                .uctx = uctx,
#ifndef NDEBUG
                .file = file,
                .line = line,
#endif
        };
 
        EV_SET(&evset, (uintptr_t)ev,
               EVFILT_USER, EV_ADD | EV_DISPATCH, (trigger * NOTE_TRIGGER), 0, ev);
 
        if (unlikely(kevent(el->kq, &evset, 1, NULL, 0, NULL) < 0)) {
                fr_strerror_printf("Failed adding user event - kevent %s", fr_syserror(evset.flags));
                talloc_free(ev);
                return -1;
        }
        ev->is_registered = true;
        talloc_set_destructor(ev, _event_user_delete);
 
        if (ev_p) *ev_p = ev;
 
        return 0;
}
 
/** Trigger a user event
 *
 * @param[in] el        containing the user event.
 * @param[in] ev        Handle for the user event.
 * @return
 *      - 0 on success.
 *      - -1 on error.
 */
int fr_event_user_trigger(fr_event_list_t *el, fr_event_user_t *ev)
{
        struct kevent evset;
 
        EV_SET(&evset, (uintptr_t)ev, EVFILT_USER, EV_ENABLE, NOTE_TRIGGER, 0, NULL);
 
        if (unlikely(kevent(el->kq, &evset, 1, NULL, 0, NULL) < 0)) {
                fr_strerror_printf("Failed triggering user event - kevent %s", fr_syserror(evset.flags));
                return -1;
        }
 
        return 0;
}
 
/** Add a pre-event callback to the event list.
 *
 *  Events are serviced in insert order.  i.e. insert A, B, we then
 *  have A running before B.
 *
 * @param[in] el        Containing the timer events.
 * @param[in] callback  The pre-processing callback.
 * @param[in] uctx      for the callback.
 * @return
 *      - < 0 on error
 *      - 0 on success
 */
int fr_event_pre_insert(fr_event_list_t *el, fr_event_status_cb_t callback, void *uctx)
{
        fr_event_pre_t *pre;
 
        pre = talloc(el, fr_event_pre_t);
        pre->callback = callback;
        pre->uctx = uctx;
 
        fr_dlist_insert_tail(&el->pre_callbacks, pre);
 
        return 0;
}
 
/** Delete a pre-event callback from the event list.
 *
 * @param[in] el        Containing the timer events.
 * @param[in] callback  The pre-processing callback.
 * @param[in] uctx      for the callback.
 * @return
 *      - < 0 on error
 *      - 0 on success
 */
int fr_event_pre_delete(fr_event_list_t *el, fr_event_status_cb_t callback, void *uctx)
{
        fr_event_pre_t *pre, *next;
 
        for (pre = fr_dlist_head(&el->pre_callbacks);
             pre != NULL;
             pre = next) {
                next = fr_dlist_next(&el->pre_callbacks, pre);
 
                if ((pre->callback == callback) &&
                    (pre->uctx == uctx)) {
                        fr_dlist_remove(&el->pre_callbacks, pre);
                        talloc_free(pre);
                        return 0;
                }
        }
 
        return -1;
}
 
/** Add a post-event callback to the event list.
 *
 *  Events are serviced in insert order.  i.e. insert A, B, we then
 *  have A running before B.
 *
 * @param[in] el        Containing the timer events.
 * @param[in] callback  The post-processing callback.
 * @param[in] uctx      for the callback.
 * @return
 *      - < 0 on error
 *      - 0 on success
 */
int fr_event_post_insert(fr_event_list_t *el, fr_event_post_cb_t callback, void *uctx)
{
        fr_event_post_t *post;
 
        post = talloc(el, fr_event_post_t);
        post->callback = callback;
        post->uctx = uctx;
 
        fr_dlist_insert_tail(&el->post_callbacks, post);
 
        return 0;
}
 
/** Delete a post-event callback from the event list.
 *
 * @param[in] el        Containing the timer events.
 * @param[in] callback  The post-processing callback.
 * @param[in] uctx      for the callback.
 * @return
 *      - < 0 on error
 *      - 0 on success
 */
int fr_event_post_delete(fr_event_list_t *el, fr_event_post_cb_t callback, void *uctx)
{
        fr_event_post_t *post, *next;
 
        for (post = fr_dlist_head(&el->post_callbacks);
             post != NULL;
             post = next) {
                next = fr_dlist_next(&el->post_callbacks, post);
 
                if ((post->callback == callback) &&
                    (post->uctx == uctx)) {
                        fr_dlist_remove(&el->post_callbacks, post);
                        talloc_free(post);
                        return 0;
                }
        }
 
        return -1;
}
 
/** Gather outstanding timer and file descriptor events
 *
 * @param[in] el        to process events for.
 * @param[in] now       The current time.
 * @param[in] wait      if true, block on the kevent() call until a timer or file descriptor event occurs.
 * @return
 *      - <0 error, or the event loop is exiting
 *      - the number of outstanding I/O events, +1 if at least one timer will fire.
 */
int fr_event_corral(fr_event_list_t *el, fr_time_t now, bool wait)
{
        fr_time_delta_t         when, *wake;
        struct timespec         ts_when, *ts_wake;
        fr_event_pre_t          *pre;
        int                     num_fd_events;
        bool                    timer_event_ready = false;
        fr_time_t               next;
 
        el->num_fd_events = 0;
 
        if (el->will_exit || el->exit) {
                el->exit = el->will_exit;
 
                fr_strerror_const("Event loop exiting");
                return -1;
        }
 
        /*
         *      By default we wait for 0ns, which means returning
         *      immediately from kevent().
         */
        when = fr_time_delta_wrap(0);
        wake = &when;
 
        /*
         *      See when we have to wake up.  Either now, if the timer
         *      events are in the past.  Or, we wait for a future
         *      timer event.
         */
        next = fr_timer_list_when(el->pub.tl);
        if (fr_time_neq(next, fr_time_wrap(0))) {
                if (fr_time_lteq(next, now)) {
                        timer_event_ready = true;
 
                } else if (wait) {
                        when = fr_time_sub(next, now);
 
                } /* else we're not waiting, leave "when == 0" */
 
        } else if (wait) {
                /*
                 *      We're asked to wait, but there's no timer
                 *      event.  We can then sleep forever.
                 */
                wake = NULL;
        }
 
        /*
         *      Run the status callbacks.  It may tell us that the
         *      application has more work to do, in which case we
         *      re-set the timeout to be instant.
         *
         *      We only run these callbacks if the caller is otherwise
         *      idle.
         */
        if (wait) {
                for (pre = fr_dlist_head(&el->pre_callbacks);
                     pre != NULL;
                     pre = fr_dlist_next(&el->pre_callbacks, pre)) {
                        if (pre->callback(now, wake ? *wake : fr_time_delta_wrap(0), pre->uctx) > 0) {
                                wake = &when;
                                when = fr_time_delta_wrap(0);
                        }
                }
        }
 
        /*
         *      Wake is the delta between el->now
         *      (the event loops view of the current time)
         *      and when the event should occur.
         */
        if (wake) {
                ts_when = fr_time_delta_to_timespec(when);
                ts_wake = &ts_when;
        } else {
                ts_wake = NULL;
        }
 
        /*
         *      Populate el->events with the list of I/O events
         *      that occurred since this function was last called
         *      or wait for the next timer event.
         */
        num_fd_events = kevent(el->kq, NULL, 0, el->events, FR_EV_BATCH_FDS, ts_wake);
 
        /*
         *      Interrupt is different from timeout / FD events.
         */
        if (unlikely(num_fd_events < 0)) {
                if (errno == EINTR) {
                        return 0;
                } else {
                        fr_strerror_printf("Failed calling kevent: %s", fr_syserror(errno));
                        return -1;
                }
        }
 
        el->num_fd_events = num_fd_events;
 
        EVENT_DEBUG("%p - %s - kevent returned %u FD events", el, __FUNCTION__, el->num_fd_events);
 
        /*
         *      If there are no FD events, we must have woken up from a timer
         */
        if (!num_fd_events) {
                if (wait) timer_event_ready = true;
        }
        /*
         *      The caller doesn't really care what the value of the
         *      return code is.  Just that it's greater than zero if
         *      events needs servicing.
         *
         *      num_fd_events     > 0 - if kevent() returns FD events
         *      timer_event_ready > 0 - if there were timers ready BEFORE or AFTER calling kevent()
         */
        return num_fd_events + timer_event_ready;
}
 
CC_NO_UBSAN(function) /* UBSAN: false positive - public vs private fr_event_list_t trips --fsanitize=function*/
static inline CC_HINT(always_inline)
void event_callback(fr_event_list_t *el, fr_event_fd_t *ef, int *filter, int flags, int *fflags)
{
        fr_event_fd_cb_t        fd_cb;
 
        while ((fd_cb = event_fd_func(ef, filter, fflags))) {
                fd_cb(el, ef->fd, flags, ef->uctx);
        }
}
 
/** Service any outstanding timer or file descriptor events
 *
 * @param[in] el containing events to service.
 */
CC_NO_UBSAN(function) /* UBSAN: false positive - Public/private version of fr_event_list_t trips -fsanitize=function */
void fr_event_service(fr_event_list_t *el)
{
        fr_timer_list_t *etl = el->pub.tl;
        int                     i;
        fr_event_post_t         *post;
        fr_time_t               when, now;
 
        if (unlikely(el->exit)) return;
 
        EVENT_DEBUG("%p - %s - Servicing %u FD events", el, __FUNCTION__, el->num_fd_events);
 
        /*
         *      Run all of the file descriptor events.
         */
        el->in_handler = true;
        for (i = 0; i < el->num_fd_events; i++) {
                /*
                 *      Process any user events
                 */
                switch (el->events[i].filter) {
                case EVFILT_USER:
                        event_user_eval(el, &el->events[i]);
                        continue;
 
                /*
                 *      Process proc events
                 */
                case EVFILT_PROC:
                        event_pid_eval(el, &el->events[i]);
                        continue;
 
                /*
                 *      Process various types of file descriptor events
                 */
                default:
                {
                        fr_event_fd_t           *ef = talloc_get_type_abort(el->events[i].udata, fr_event_fd_t);
                        int                     fd_errno = 0;
 
                        int                     fflags = el->events[i].fflags;  /* mutable */
                        int                     filter = el->events[i].filter;
                        int                     flags = el->events[i].flags;
 
                        if (!ef->is_registered) continue;       /* Was deleted between corral and service */
 
                        if (unlikely(flags & EV_ERROR)) {
                                fd_errno = el->events[i].data;
                        ev_error:
                                /*
                                 *      Call the error handler, but only if the socket hasn't been deleted at EOF
                                 *      below.
                                 */
                                if (ef->is_registered && ef->error) ef->error(el, ef->fd, flags, fd_errno, ef->uctx);
                                TALLOC_FREE(ef);
                                continue;
                        }
 
                        /*
                         *      EOF can indicate we've actually reached
                         *      the end of a file, but for sockets it usually
                         *      indicates the other end of the connection
                         *      has gone away.
                         */
                        if (flags & EV_EOF) {
                                /*
                                 *      This is fine, the callback will get notified
                                 *      via the flags field.
                                 */
                                if (ef->type == FR_EVENT_FD_FILE) goto service;
#if defined(__linux__) && defined(SO_GET_FILTER)
                                /*
                                 *      There seems to be an issue with the
                                 *      ioctl(...SIOCNQ...) call libkqueue
                                 *      uses to determine the number of bytes
                                 *      readable.  When ioctl returns, the number
                                 *      of bytes available is set to zero, which
                                 *      libkqueue interprets as EOF.
                                 *
                                 *      As a workaround, if we're not reading
                                 *      a file, and are operating on a raw socket
                                 *      with a packet filter attached, we ignore
                                 *      the EOF flag and continue.
                                 */
                                if ((ef->sock_type == SOCK_RAW) && (ef->type == FR_EVENT_FD_PCAP)) goto service;
#endif
 
                                /*
                                 *      If we see an EV_EOF flag that means the
                                 *      read side of the socket has been closed
                                 *      but there may still be pending data.
                                 *
                                 *      Dispatch the read event and then error.
                                 */
                                if ((el->events[i].filter == EVFILT_READ) && (el->events[i].data > 0)) {
                                        event_callback(el, ef, &filter, flags, &fflags);
                                }
 
                                fd_errno = el->events[i].fflags;
 
                                goto ev_error;
                        }
 
                service:
#ifndef NDEBUG
                        EVENT_DEBUG("Running event for fd %d, from %s[%d]", ef->fd, ef->file, ef->line);
#endif
 
                        /*
                         *      Service the event_fd events
                         */
                        event_callback(el, ef, &filter, flags, &fflags);
                }
                }
        }
 
        /*
         *      Process any deferred frees performed
         *      by the I/O handlers.
         *
         *      The events are removed from the FD rbtree
         *      and kevent immediately, but frees are
         *      deferred to allow stale events to be
         *      skipped sans SEGV.
         */
        el->in_handler = false; /* Allow events to be deleted */
        {
                fr_event_fd_t *ef;
 
                while ((ef = fr_dlist_head(&el->fd_to_free))) talloc_free(ef);
        }
 
        /*
         *      We must call el->time() again here, else the event
         *      list's time gets updated too infrequently, and we
         *      can end up with a situation where timers are
         *      serviced much later than they should be, which can
         *      cause strange interaction effects, spurious calls
         *      to kevent, and busy loops.
         */
        now = etl->time();
 
        /*
         *      Run all of the timer events.  Note that these can add
         *      new timers!
         */
        if (fr_time_neq(fr_timer_list_when(el->pub.tl), fr_time_wrap(0))) {
                int ret;
 
                when = now;
 
                ret = fr_timer_list_run(etl, &when);
                if (!fr_cond_assert(ret >= 0)) {        /* catastrophic error, trigger event loop exit */
                        el->exit = 1;
                        return;
                }
 
                EVENT_DEBUG("%p - %s - Serviced %u timer(s)", el, __FUNCTION__, (unsigned int)ret);
        }
 
        now = etl->time();
 
        /*
         *      Run all of the post-processing events.
         */
        for (post = fr_dlist_head(&el->post_callbacks);
             post != NULL;
             post = fr_dlist_next(&el->post_callbacks, post)) {
                post->callback(el, now, post->uctx);
        }
}
 
/** Signal an event loop exit with the specified code
 *
 * The event loop will complete its current iteration, and then exit with the specified code.
 *
 * @param[in] el        to signal to exit.
 * @param[in] code      for #fr_event_loop to return.
 */
void fr_event_loop_exit(fr_event_list_t *el, int code)
{
        if (unlikely(!el)) return;
 
        el->will_exit = code;
}
 
/** Check to see whether the event loop is in the process of exiting
 *
 * @param[in] el        to check.
 */
bool fr_event_loop_exiting(fr_event_list_t *el)
{
        return ((el->will_exit != 0) || (el->exit != 0));
}
 
/** Run an event loop
 *
 * @note Will not return until #fr_event_loop_exit is called.
 *
 * @param[in] el to start processing.
 */
CC_HINT(flatten) int fr_event_loop(fr_event_list_t *el)
{
        el->will_exit = el->exit = 0;
 
        el->dispatch = true;
        while (!el->exit) {
                if (unlikely(fr_event_corral(el, el->pub.tl->time(), true)) < 0) break;
                fr_event_service(el);
        }
 
        /*
         *      Give processes five seconds to exit.
         *      This means any triggers that we may
         *      have issued when the server exited
         *      have a chance to complete.
         */
        fr_event_list_reap_signal(el, fr_time_delta_from_sec(5), SIGKILL);
        el->dispatch = false;
 
        return el->exit;
}
 
/** Cleanup an event list
 *
 * Frees/destroys any resources associated with an event list
 *
 * @param[in] el to free resources for.
 */
static int _event_list_free(fr_event_list_t *el)
{
        fr_event_list_reap_signal(el, fr_time_delta_wrap(0), SIGKILL);
 
        talloc_free_children(el);
 
        if (el->kq >= 0) close(el->kq);
 
        return 0;
}
 
/** Free any memory we allocated for indexes
 *
 */
static int _event_free_indexes(UNUSED void *uctx)
{
        unsigned int i;
 
        for (i = 0; i < NUM_ELEMENTS(filter_maps); i++) if (talloc_free(filter_maps[i].ev_to_func) < 0) return -1;
        return 0;
}
 
static int _event_build_indexes(UNUSED void *uctx)
{
        unsigned int i;
 
        for (i = 0; i < NUM_ELEMENTS(filter_maps); i++) event_fd_func_index_build(&filter_maps[i]);
        return 0;
}
 
#ifdef EVFILT_LIBKQUEUE
/** kqueue logging wrapper function
 *
 */
static CC_HINT(format (printf, 1, 2)) CC_HINT(nonnull)
void _event_kqueue_log(char const *fmt, ...)
{
        va_list ap;
 
        va_start(ap, fmt);
        fr_vlog(&default_log, L_DBG, __FILE__, __LINE__, fmt, ap);
        va_end(ap);
}
 
/** If we're building with libkqueue, and at debug level 4 or higher, enable libkqueue debugging output
 *
 * This requires a debug build of libkqueue
 */
static int _event_kqueue_logging(UNUSED void *uctx)
{
        struct kevent kev, receipt;
 
        log_conf_kq = kqueue();
        if (unlikely(log_conf_kq < 0)) {
                fr_strerror_const("Failed initialising logging configuration kqueue");
                return -1;
        }
 
        EV_SET(&kev, 0, EVFILT_LIBKQUEUE, EV_ADD, NOTE_DEBUG_FUNC, (intptr_t)_event_kqueue_log, NULL);
        if (kevent(log_conf_kq, &kev, 1, &receipt, 1, &(struct timespec){}) != 1) {
                close(log_conf_kq);
                log_conf_kq = -1;
                return 1;
        }
 
        if (fr_debug_lvl >= L_DBG_LVL_3) {
                EV_SET(&kev, 0, EVFILT_LIBKQUEUE, EV_ADD, NOTE_DEBUG, 1, NULL);
                if (kevent(log_conf_kq, &kev, 1, &receipt, 1, &(struct timespec){}) != 1) {
                        fr_strerror_const("Failed enabling libkqueue debug logging");
                        close(log_conf_kq);
                        log_conf_kq = -1;
                        return -1;
                }
        }
 
        return 0;
}
 
static int _event_kqueue_logging_stop(UNUSED void *uctx)
{
        struct kevent kev, receipt;
 
        EV_SET(&kev, 0, EVFILT_LIBKQUEUE, EV_ADD, NOTE_DEBUG_FUNC, 0, NULL);
        (void)kevent(log_conf_kq, &kev, 1, &receipt, 1, &(struct timespec){});
 
        close(log_conf_kq);
        log_conf_kq = -1;
 
        return 0;
}
#endif
 
/** Initialise a new event list
 *
 * @param[in] ctx               to allocate memory in.
 * @param[in] status            callback, called on each iteration of the event list.
 * @param[in] status_uctx       context for the status callback
 * @return
 *      - A pointer to a new event list on success (free with talloc_free).
 *      - NULL on error.
 */
fr_event_list_t *fr_event_list_alloc(TALLOC_CTX *ctx, fr_event_status_cb_t status, void *status_uctx)
{
        fr_event_list_t         *el;
        struct kevent           kev;
        int                     ret;
 
        /*
         *      Build the map indexes the first time this
         *      function is called.
         */
        fr_atexit_global_once_ret(&ret, _event_build_indexes, _event_free_indexes, NULL);
#ifdef EVFILT_LIBKQUEUE
        fr_atexit_global_once_ret(&ret, _event_kqueue_logging, _event_kqueue_logging_stop, NULL);
#endif
 
        el = talloc_zero(ctx, fr_event_list_t);
        if (!fr_cond_assert(el)) {
                fr_strerror_const("Out of memory");
                return NULL;
        }
        el->kq = -1;    /* So destructor can be used before kqueue() provides us with fd */
        talloc_set_destructor(el, _event_list_free);
 
        el->pub.tl = fr_timer_list_lst_alloc(el, NULL);
        if (!el->pub.tl) {
                fr_strerror_const("Failed allocating timer list");
        error:
                talloc_free(el);
                return NULL;
        }
 
        el->fds = fr_rb_inline_talloc_alloc(el, fr_event_fd_t, node, fr_event_fd_cmp, NULL);
        if (!el->fds) {
                fr_strerror_const("Failed allocating FD tree");
                goto error;
        }
 
        el->kq = kqueue();
        if (el->kq < 0) {
                fr_strerror_printf("Failed allocating kqueue: %s", fr_syserror(errno));
                goto error;
        }
 
        fr_dlist_talloc_init(&el->pre_callbacks, fr_event_pre_t, entry);
        fr_dlist_talloc_init(&el->post_callbacks, fr_event_post_t, entry);
        fr_dlist_talloc_init(&el->pid_to_reap, fr_event_pid_reap_t, entry);
        fr_dlist_talloc_init(&el->fd_to_free, fr_event_fd_t, entry);
        if (status) (void) fr_event_pre_insert(el, status, status_uctx);
 
        /*
         *      Set our "exit" callback as ident 0.
         */
        EV_SET(&kev, 0, EVFILT_USER, EV_ADD | EV_CLEAR, NOTE_FFNOP, 0, NULL);
        if (kevent(el->kq, &kev, 1, NULL, 0, NULL) < 0) {
                fr_strerror_printf("Failed adding exit callback to kqueue: %s", fr_syserror(errno));
                goto error;
        }
 
        return el;
}
 
/** Return whether the event loop has any active events
 *
 */
bool fr_event_list_empty(fr_event_list_t *el)
{
        return fr_time_eq(fr_timer_list_when(el->pub.tl), fr_time_wrap(0)) && (fr_rb_num_elements(el->fds) == 0);
}
#ifdef TESTING
/*
 *  cc -g -I .. -c rb.c -o rbtree.o && cc -g -I .. -c isaac.c -o isaac.o && cc -DTESTING -I .. -c event.c  -o event_mine.o && cc event_mine.o rbtree.o isaac.o -o event
 *
 *  ./event
 *
 *  And hit CTRL-S to stop the output, CTRL-Q to continue.
 *  It normally alternates printing the time and sleeping,
 *  but when you hit CTRL-S/CTRL-Q, you should see a number
 *  of events run right after each other.
 *
 *  OR
 *
 *   valgrind --tool=memcheck --leak-check=full --show-reachable=yes ./event
 */
 
static void print_time(void *ctx)
{
        fr_time_t when;
        int64_t usec;
 
        when = *(fr_time_t *) ctx;
        usec = fr_time_to_usec(when);
 
        printf("%d.%06d\n", usec / USEC, usec % USEC);
        fflush(stdout);
}
 
static fr_randctx rand_pool;
 
static uint32_t event_rand(void)
{
        uint32_t num;
 
        num = rand_pool.randrsl[rand_pool.randcnt++];
        if (rand_pool.randcnt == 256) {
                fr_isaac(&rand_pool);
                rand_pool.randcnt = 0;
        }
 
        return num;
}
 
 
#define MAX 100
int main(int argc, char **argv)
{
        int i, rcode;
        fr_time_t array[MAX];
        fr_time_t now, when;
        fr_event_list_t *el;
 
        el = fr_event_list_alloc(NULL, NULL);
        if (!el) fr_exit_now(1);
 
        memset(&rand_pool, 0, sizeof(rand_pool));
        rand_pool.randrsl[1] = time(NULL);
 
        fr_rand_init(&rand_pool, 1);
        rand_pool.randcnt = 0;
 
        array[0] = el->time();
        for (i = 1; i < MAX; i++) {
                array[i] = array[i - 1];
                array[i] += event_rand() & 0xffff;
 
                fr_timer_at(NULL, el, array[i], false, print_time, array[i]);
        }
 
        while (fr_event_list_num_timers(el)) {
                now = el->time();
                when = now;
                if (!fr_timer_run(el, &when)) {
                        int delay = (when - now) / 1000;        /* nanoseconds to microseconds */
 
                        printf("\tsleep %d microseconds\n", delay);
                        fflush(stdout);
                        usleep(delay);
                }
        }
 
        talloc_free(el);
 
        return 0;
}
#endif