/src/libevent/evmap.c

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/*
 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "event2/event-config.h"
#include "evconfig-private.h"

#ifdef _WIN32
#include <winsock2.h>
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#endif
#include <sys/types.h>
#if !defined(_WIN32) && defined(EVENT__HAVE_SYS_TIME_H)
#include <sys/time.h>
#endif
#include <sys/queue.h>
#include <stdio.h>
#include <stdlib.h>
#ifndef _WIN32
#include <unistd.h>
#endif
#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <string.h>
#include <time.h>

#include "event-internal.h"
#include "evmap-internal.h"
#include "mm-internal.h"
#include "changelist-internal.h"

/** An entry for an evmap_io list: notes all the events that want to read or
  write on a given fd, and the number of each.
  */
struct evmap_io {
  struct event_dlist events;
  ev_uint16_t nread;
  ev_uint16_t nwrite;
  ev_uint16_t nclose;
};

/* An entry for an evmap_signal list: notes all the events that want to know
   when a signal triggers. */
struct evmap_signal {
  struct event_dlist events;
};

/* On some platforms, fds start at 0 and increment by 1 as they are
   allocated, and old numbers get used.  For these platforms, we
   implement io maps just like signal maps: as an array of pointers to
   struct evmap_io.  But on other platforms (windows), sockets are not
   0-indexed, not necessarily consecutive, and not necessarily reused.
   There, we use a hashtable to implement evmap_io.
*/
#ifdef EVMAP_USE_HT
struct event_map_entry {
  HT_ENTRY(event_map_entry) map_node;
  evutil_socket_t fd;
  union { /* This is a union in case we need to make more things that can
         be in the hashtable. */
    struct evmap_io evmap_io;
  } ent;
};

/* Helper used by the event_io_map hashtable code; tries to return a good hash
 * of the fd in e->fd. */
static inline unsigned
hashsocket(struct event_map_entry *e)
{
  /* On win32, in practice, the low 2-3 bits of a SOCKET seem not to
   * matter.  Our hashtable implementation really likes low-order bits,
   * though, so let's do the rotate-and-add trick. */
  unsigned h = (unsigned) e->fd;
  h = (h >> 2) | (h << 30);
  return h;
}

/* Helper used by the event_io_map hashtable code; returns true iff e1 and e2
 * have the same e->fd. */
static inline int
eqsocket(struct event_map_entry *e1, struct event_map_entry *e2)
{
  return e1->fd == e2->fd;
}

HT_PROTOTYPE(event_io_map, event_map_entry, map_node, hashsocket, eqsocket)
HT_GENERATE(event_io_map, event_map_entry, map_node, hashsocket, eqsocket,
      0.5, mm_malloc, mm_realloc, mm_free)

#define GET_IO_SLOT(x, map, slot, type)         \
  do {                \
    struct event_map_entry key_, *ent_;     \
    key_.fd = slot;           \
    ent_ = HT_FIND(event_io_map, map, &key_);   \
    (x) = ent_ ? &ent_->ent.type : NULL;      \
  } while (0);

#define GET_IO_SLOT_AND_CTOR(x, map, slot, type, ctor, fdinfo_len)  \
  do {                \
    struct event_map_entry key_, *ent_;     \
    key_.fd = slot;           \
    HT_FIND_OR_INSERT_(event_io_map, map_node, hashsocket, map, \
        event_map_entry, &key_, ptr,      \
        {             \
          ent_ = *ptr;        \
        },              \
        {             \
          ent_ = mm_calloc(1,sizeof(struct event_map_entry)+fdinfo_len); \
          if (EVUTIL_UNLIKELY(ent_ == NULL))    \
            return (-1);      \
          ent_->fd = slot;        \
          (ctor)(&ent_->ent.type);      \
          HT_FOI_INSERT_(map_node, map, &key_, ent_, ptr) \
        });         \
    (x) = &ent_->ent.type;          \
  } while (0)

void evmap_io_initmap_(struct event_io_map *ctx)
{
  HT_INIT(event_io_map, ctx);
}

void evmap_io_clear_(struct event_io_map *ctx)
{
  struct event_map_entry **ent, **next, *this;
  for (ent = HT_START(event_io_map, ctx); ent; ent = next) {
    this = *ent;
    next = HT_NEXT_RMV(event_io_map, ctx, ent);
    mm_free(this);
  }
  HT_CLEAR(event_io_map, ctx); /* remove all storage held by the ctx. */
}
#endif

/* Set the variable 'x' to the field in event_map 'map' with fields of type
   'struct type *' corresponding to the fd or signal 'slot'.  Set 'x' to NULL
   if there are no entries for 'slot'.  Does no bounds-checking. */
#define GET_SIGNAL_SLOT(x, map, slot, type)     \
  (x) = (struct type *)((map)->entries[slot])
/* As GET_SLOT, but construct the entry for 'slot' if it is not present,
   by allocating enough memory for a 'struct type', and initializing the new
   value by calling the function 'ctor' on it.  Makes the function
   return -1 on allocation failure.
 */
#define GET_SIGNAL_SLOT_AND_CTOR(x, map, slot, type, ctor, fdinfo_len)  \
  do {               \
    if ((map)->entries[slot] == NULL) {     \
      (map)->entries[slot] =        \
          mm_calloc(1,sizeof(struct type)+fdinfo_len); \
      if (EVUTIL_UNLIKELY((map)->entries[slot] == NULL)) \
        return (-1);       \
      (ctor)((struct type *)(map)->entries[slot]);  \
    }              \
    (x) = (struct type *)((map)->entries[slot]);    \
  } while (0)

/* If we aren't using hashtables, then define the IO_SLOT macros and functions
   as thin aliases over the SIGNAL_SLOT versions. */
#ifndef EVMAP_USE_HT
#define GET_IO_SLOT(x,map,slot,type) GET_SIGNAL_SLOT(x,map,slot,type)
#define GET_IO_SLOT_AND_CTOR(x,map,slot,type,ctor,fdinfo_len) \
  GET_SIGNAL_SLOT_AND_CTOR(x,map,slot,type,ctor,fdinfo_len)
#define FDINFO_OFFSET sizeof(struct evmap_io)
void
evmap_io_initmap_(struct event_io_map* ctx)
{
  evmap_signal_initmap_(ctx);
}
void
evmap_io_clear_(struct event_io_map* ctx)
{
  evmap_signal_clear_(ctx);
}
#endif


/** Expand 'map' with new entries of width 'msize' until it is big enough
  to store a value in 'slot'.
 */
static int
evmap_make_space(struct event_signal_map *map, int slot, int msize)
{
  if (map->nentries <= slot) {
    int nentries = map->nentries ? map->nentries : 32;
    void **tmp;

    if (slot > INT_MAX / 2)
      return (-1);

    while (nentries <= slot)
      nentries <<= 1;

    if (nentries > INT_MAX / msize)
      return (-1);

    tmp = (void **)mm_realloc(map->entries, nentries * msize);
    if (tmp == NULL)
      return (-1);

    memset(&tmp[map->nentries], 0,
        (nentries - map->nentries) * msize);

    map->nentries = nentries;
    map->entries = tmp;
  }

  return (0);
}

void
evmap_signal_initmap_(struct event_signal_map *ctx)
{
  ctx->nentries = 0;
  ctx->entries = NULL;
}

void
evmap_signal_clear_(struct event_signal_map *ctx)
{
  if (ctx->entries != NULL) {
    int i;
    for (i = 0; i < ctx->nentries; ++i) {
      if (ctx->entries[i] != NULL)
        mm_free(ctx->entries[i]);
    }
    mm_free(ctx->entries);
    ctx->entries = NULL;
  }
  ctx->nentries = 0;
}


/* code specific to file descriptors */

/** Constructor for struct evmap_io */
static void
evmap_io_init(struct evmap_io *entry)
{
  LIST_INIT(&entry->events);
  entry->nread = 0;
  entry->nwrite = 0;
  entry->nclose = 0;
}


/* return -1 on error, 0 on success if nothing changed in the event backend,
 * and 1 on success if something did. */
int
evmap_io_add_(struct event_base *base, evutil_socket_t fd, struct event *ev)
{
  const struct eventop *evsel = base->evsel;
  struct event_io_map *io = &base->io;
  struct evmap_io *ctx = NULL;
  int nread, nwrite, nclose, retval = 0;
  short res = 0, old = 0;
  struct event *old_ev;

  EVUTIL_ASSERT(fd == ev->ev_fd);

  if (fd < 0)
    return 0;

#ifndef EVMAP_USE_HT
  if (fd >= io->nentries) {
    if (evmap_make_space(io, fd, sizeof(struct evmap_io *)) == -1)
      return (-1);
  }
#endif
  GET_IO_SLOT_AND_CTOR(ctx, io, fd, evmap_io, evmap_io_init,
             evsel->fdinfo_len);

  nread = ctx->nread;
  nwrite = ctx->nwrite;
  nclose = ctx->nclose;

  if (nread)
    old |= EV_READ;
  if (nwrite)
    old |= EV_WRITE;
  if (nclose)
    old |= EV_CLOSED;

  if (ev->ev_events & EV_READ) {
    if (++nread == 1)
      res |= EV_READ;
  }
  if (ev->ev_events & EV_WRITE) {
    if (++nwrite == 1)
      res |= EV_WRITE;
  }
  if (ev->ev_events & EV_CLOSED) {
    if (++nclose == 1)
      res |= EV_CLOSED;
  }
  if (EVUTIL_UNLIKELY(nread > 0xffff || nwrite > 0xffff || nclose > 0xffff)) {
    event_warnx("Too many events reading or writing on fd %d",
        (int)fd);
    return -1;
  }
  if (EVENT_DEBUG_MODE_IS_ON() &&
      (old_ev = LIST_FIRST(&ctx->events)) &&
      (old_ev->ev_events&EV_ET) != (ev->ev_events&EV_ET)) {
    event_warnx("Tried to mix edge-triggered and non-edge-triggered"
        " events on fd %d", (int)fd);
    return -1;
  }

  if (res) {
    void *extra = ((char*)ctx) + sizeof(struct evmap_io);
    /* XXX(niels): we cannot mix edge-triggered and
     * level-triggered, we should probably assert on
     * this. */
    if (evsel->add(base, ev->ev_fd,
      old, (ev->ev_events & EV_ET) | res, extra) == -1)
      return (-1);
    retval = 1;
  }

  ctx->nread = (ev_uint16_t) nread;
  ctx->nwrite = (ev_uint16_t) nwrite;
  ctx->nclose = (ev_uint16_t) nclose;
  LIST_INSERT_HEAD(&ctx->events, ev, ev_io_next);

  return (retval);
}

/* return -1 on error, 0 on success if nothing changed in the event backend,
 * and 1 on success if something did. */
int
evmap_io_del_(struct event_base *base, evutil_socket_t fd, struct event *ev)
{
  const struct eventop *evsel = base->evsel;
  struct event_io_map *io = &base->io;
  struct evmap_io *ctx;
  int nread, nwrite, nclose, retval = 0;
  short res = 0, old = 0;

  if (fd < 0)
    return 0;

  EVUTIL_ASSERT(fd == ev->ev_fd);

#ifndef EVMAP_USE_HT
  if (fd >= io->nentries)
    return (-1);
#endif

  GET_IO_SLOT(ctx, io, fd, evmap_io);

  nread = ctx->nread;
  nwrite = ctx->nwrite;
  nclose = ctx->nclose;

  if (nread)
    old |= EV_READ;
  if (nwrite)
    old |= EV_WRITE;
  if (nclose)
    old |= EV_CLOSED;

  if (ev->ev_events & EV_READ) {
    if (--nread == 0)
      res |= EV_READ;
    EVUTIL_ASSERT(nread >= 0);
  }
  if (ev->ev_events & EV_WRITE) {
    if (--nwrite == 0)
      res |= EV_WRITE;
    EVUTIL_ASSERT(nwrite >= 0);
  }
  if (ev->ev_events & EV_CLOSED) {
    if (--nclose == 0)
      res |= EV_CLOSED;
    EVUTIL_ASSERT(nclose >= 0);
  }

  if (res) {
    void *extra = ((char*)ctx) + sizeof(struct evmap_io);
    if (evsel->del(base, ev->ev_fd,
      old, (ev->ev_events & EV_ET) | res, extra) == -1) {
      retval = -1;
    } else {
      retval = 1;
    }
  }

  ctx->nread = nread;
  ctx->nwrite = nwrite;
  ctx->nclose = nclose;
  LIST_REMOVE(ev, ev_io_next);

  return (retval);
}

void
evmap_io_active_(struct event_base *base, evutil_socket_t fd, short events)
{
  struct event_io_map *io = &base->io;
  struct evmap_io *ctx;
  struct event *ev;

#ifndef EVMAP_USE_HT
  if (fd < 0 || fd >= io->nentries)
    return;
#endif
  GET_IO_SLOT(ctx, io, fd, evmap_io);

  if (NULL == ctx)
    return;
  LIST_FOREACH(ev, &ctx->events, ev_io_next) {
    if (ev->ev_events & (events & ~EV_ET))
      event_active_nolock_(ev, ev->ev_events & events, 1);
  }
}

/* code specific to signals */

static void
evmap_signal_init(struct evmap_signal *entry)
{
  LIST_INIT(&entry->events);
}


int
evmap_signal_add_(struct event_base *base, int sig, struct event *ev)
{
  const struct eventop *evsel = base->evsigsel;
  struct event_signal_map *map = &base->sigmap;
  struct evmap_signal *ctx = NULL;

  if (sig < 0 || sig >= NSIG)
    return (-1);

  if (sig >= map->nentries) {
    if (evmap_make_space(
      map, sig, sizeof(struct evmap_signal *)) == -1)
      return (-1);
  }
  GET_SIGNAL_SLOT_AND_CTOR(ctx, map, sig, evmap_signal, evmap_signal_init,
      base->evsigsel->fdinfo_len);

  if (LIST_EMPTY(&ctx->events)) {
    if (evsel->add(base, ev->ev_fd, 0, EV_SIGNAL, ev)
        == -1)
      return (-1);
  }

  LIST_INSERT_HEAD(&ctx->events, ev, ev_signal_next);

  return (1);
}

int
evmap_signal_del_(struct event_base *base, int sig, struct event *ev)
{
  const struct eventop *evsel = base->evsigsel;
  struct event_signal_map *map = &base->sigmap;
  struct evmap_signal *ctx;

  if (sig < 0 || sig >= map->nentries)
    return (-1);

  GET_SIGNAL_SLOT(ctx, map, sig, evmap_signal);

  LIST_REMOVE(ev, ev_signal_next);

  if (LIST_FIRST(&ctx->events) == NULL) {
    if (evsel->del(base, ev->ev_fd, 0, EV_SIGNAL, NULL) == -1)
      return (-1);
  }

  return (1);
}

void
evmap_signal_active_(struct event_base *base, evutil_socket_t sig, int ncalls)
{
  struct event_signal_map *map = &base->sigmap;
  struct evmap_signal *ctx;
  struct event *ev;

  if (sig < 0 || sig >= map->nentries)
    return;
  GET_SIGNAL_SLOT(ctx, map, sig, evmap_signal);

  if (!ctx)
    return;
  LIST_FOREACH(ev, &ctx->events, ev_signal_next)
    event_active_nolock_(ev, EV_SIGNAL, ncalls);
}

void *
evmap_io_get_fdinfo_(struct event_io_map *map, evutil_socket_t fd)
{
  struct evmap_io *ctx;
  GET_IO_SLOT(ctx, map, fd, evmap_io);
  if (ctx)
    return ((char*)ctx) + sizeof(struct evmap_io);
  else
    return NULL;
}

/* Callback type for evmap_io_foreach_fd */
typedef int (*evmap_io_foreach_fd_cb)(
  struct event_base *, evutil_socket_t, struct evmap_io *, void *);

/* Multipurpose helper function: Iterate over every file descriptor event_base
 * for which we could have EV_READ or EV_WRITE events.  For each such fd, call
 * fn(base, signum, evmap_io, arg), where fn is the user-provided
 * function, base is the event_base, signum is the signal number, evmap_io
 * is an evmap_io structure containing a list of events pending on the
 * file descriptor, and arg is the user-supplied argument.
 *
 * If fn returns 0, continue on to the next signal. Otherwise, return the same
 * value that fn returned.
 *
 * Note that there is no guarantee that the file descriptors will be processed
 * in any particular order.
 */
static int
evmap_io_foreach_fd(struct event_base *base,
    evmap_io_foreach_fd_cb fn,
    void *arg)
{
  evutil_socket_t fd;
  struct event_io_map *iomap = &base->io;
  int r = 0;
#ifdef EVMAP_USE_HT
  struct event_map_entry **mapent;
  HT_FOREACH(mapent, event_io_map, iomap) {
    struct evmap_io *ctx = &(*mapent)->ent.evmap_io;
    fd = (*mapent)->fd;
#else
  for (fd = 0; fd < iomap->nentries; ++fd) {
    struct evmap_io *ctx = iomap->entries[fd];
    if (!ctx)
      continue;
#endif
    if ((r = fn(base, fd, ctx, arg)))
      break;
  }
  return r;
}

/* Callback type for evmap_signal_foreach_signal */
typedef int (*evmap_signal_foreach_signal_cb)(
  struct event_base *, int, struct evmap_signal *, void *);

/* Multipurpose helper function: Iterate over every signal number in the
 * event_base for which we could have signal events.  For each such signal,
 * call fn(base, signum, evmap_signal, arg), where fn is the user-provided
 * function, base is the event_base, signum is the signal number, evmap_signal
 * is an evmap_signal structure containing a list of events pending on the
 * signal, and arg is the user-supplied argument.
 *
 * If fn returns 0, continue on to the next signal. Otherwise, return the same
 * value that fn returned.
 */
static int
evmap_signal_foreach_signal(struct event_base *base,
    evmap_signal_foreach_signal_cb fn,
    void *arg)
{
  struct event_signal_map *sigmap = &base->sigmap;
  int r = 0;
  int signum;

  for (signum = 0; signum < sigmap->nentries; ++signum) {
    struct evmap_signal *ctx = sigmap->entries[signum];
    if (!ctx)
      continue;
    if ((r = fn(base, signum, ctx, arg)))
      break;
  }
  return r;
}

/* Helper for evmap_reinit_: tell the backend to add every fd for which we have
 * pending events, with the appropriate combination of EV_READ, EV_WRITE, and
 * EV_ET. */
static int
evmap_io_reinit_iter_fn(struct event_base *base, evutil_socket_t fd,
    struct evmap_io *ctx, void *arg)
{
  const struct eventop *evsel = base->evsel;
  void *extra;
  int *result = arg;
  short events = 0;
  struct event *ev;
  EVUTIL_ASSERT(ctx);

  extra = ((char*)ctx) + sizeof(struct evmap_io);
  if (ctx->nread)
    events |= EV_READ;
  if (ctx->nwrite)
    events |= EV_WRITE;
  if (ctx->nclose)
    events |= EV_CLOSED;
  if (evsel->fdinfo_len)
    memset(extra, 0, evsel->fdinfo_len);
  if (events &&
      (ev = LIST_FIRST(&ctx->events)) &&
      (ev->ev_events & EV_ET))
    events |= EV_ET;
  if (evsel->add(base, fd, 0, events, extra) == -1)
    *result = -1;

  return 0;
}

/* Helper for evmap_reinit_: tell the backend to add every signal for which we
 * have pending events.  */
static int
evmap_signal_reinit_iter_fn(struct event_base *base,
    int signum, struct evmap_signal *ctx, void *arg)
{
  const struct eventop *evsel = base->evsigsel;
  int *result = arg;

  if (!LIST_EMPTY(&ctx->events)) {
    if (evsel->add(base, signum, 1, EV_SIGNAL,
             LIST_FIRST(&ctx->events)) == -1)
      *result = -1;
  }
  return 0;
}

int
evmap_reinit_(struct event_base *base)
{
  int result = 0;

  evmap_io_foreach_fd(base, evmap_io_reinit_iter_fn, &result);
  if (result < 0)
    return -1;
  evmap_signal_foreach_signal(base, evmap_signal_reinit_iter_fn, &result);
  if (result < 0)
    return -1;
  return 0;
}

/* Helper for evmap_delete_all_: delete every event in an event_dlist. */
static int
delete_all_in_dlist(struct event_dlist *dlist)
{
  struct event *ev;
  while ((ev = LIST_FIRST(dlist)))
    event_del(ev);
  return 0;
}

/* Helper for evmap_delete_all_: delete every event pending on an fd. */
static int
evmap_io_delete_all_iter_fn(struct event_base *base, evutil_socket_t fd,
    struct evmap_io *io_info, void *arg)
{
  return delete_all_in_dlist(&io_info->events);
}

/* Helper for evmap_delete_all_: delete every event pending on a signal. */
static int
evmap_signal_delete_all_iter_fn(struct event_base *base, int signum,
    struct evmap_signal *sig_info, void *arg)
{
  return delete_all_in_dlist(&sig_info->events);
}

void
evmap_delete_all_(struct event_base *base)
{
  evmap_signal_foreach_signal(base, evmap_signal_delete_all_iter_fn, NULL);
  evmap_io_foreach_fd(base, evmap_io_delete_all_iter_fn, NULL);
}

/** Per-fd structure for use with changelists.  It keeps track, for each fd or
 * signal using the changelist, of where its entry in the changelist is.
 */
struct event_changelist_fdinfo {
  int idxplus1; /* this is the index +1, so that memset(0) will make it
           * a no-such-element */
};

void
event_changelist_init_(struct event_changelist *changelist)
{
  changelist->changes = NULL;
  changelist->changes_size = 0;
  changelist->n_changes = 0;
}

/** Helper: return the changelist_fdinfo corresponding to a given change. */
static inline struct event_changelist_fdinfo *
event_change_get_fdinfo(struct event_base *base,
    const struct event_change *change)
{
  char *ptr;
  if (change->read_change & EV_CHANGE_SIGNAL) {
    struct evmap_signal *ctx;
    GET_SIGNAL_SLOT(ctx, &base->sigmap, change->fd, evmap_signal);
    ptr = ((char*)ctx) + sizeof(struct evmap_signal);
  } else {
    struct evmap_io *ctx;
    GET_IO_SLOT(ctx, &base->io, change->fd, evmap_io);
    ptr = ((char*)ctx) + sizeof(struct evmap_io);
  }
  return (void*)ptr;
}

/** Callback helper for event_changelist_assert_ok */
static int
event_changelist_assert_ok_foreach_iter_fn(
  struct event_base *base,
  evutil_socket_t fd, struct evmap_io *io, void *arg)
{
  struct event_changelist *changelist = &base->changelist;
  struct event_changelist_fdinfo *f;
  f = (void*)
      ( ((char*)io) + sizeof(struct evmap_io) );
  if (f->idxplus1) {
    struct event_change *c = &changelist->changes[f->idxplus1 - 1];
    EVUTIL_ASSERT(c->fd == fd);
  }
  return 0;
}

/** Make sure that the changelist is consistent with the evmap structures. */
static void
event_changelist_assert_ok(struct event_base *base)
{
  int i;
  struct event_changelist *changelist = &base->changelist;

  EVUTIL_ASSERT(changelist->changes_size >= changelist->n_changes);
  for (i = 0; i < changelist->n_changes; ++i) {
    struct event_change *c = &changelist->changes[i];
    struct event_changelist_fdinfo *f;
    EVUTIL_ASSERT(c->fd >= 0);
    f = event_change_get_fdinfo(base, c);
    EVUTIL_ASSERT(f);
    EVUTIL_ASSERT(f->idxplus1 == i + 1);
  }

  evmap_io_foreach_fd(base,
      event_changelist_assert_ok_foreach_iter_fn,
      NULL);
}

#ifdef DEBUG_CHANGELIST
#define event_changelist_check(base)  event_changelist_assert_ok((base))
#else
#define event_changelist_check(base)  ((void)0)
#endif

void
event_changelist_remove_all_(struct event_changelist *changelist,
    struct event_base *base)
{
  int i;

  event_changelist_check(base);

  for (i = 0; i < changelist->n_changes; ++i) {
    struct event_change *ch = &changelist->changes[i];
    struct event_changelist_fdinfo *fdinfo =
        event_change_get_fdinfo(base, ch);
    EVUTIL_ASSERT(fdinfo->idxplus1 == i + 1);
    fdinfo->idxplus1 = 0;
  }

  changelist->n_changes = 0;

  event_changelist_check(base);
}

void
event_changelist_freemem_(struct event_changelist *changelist)
{
  if (changelist->changes)
    mm_free(changelist->changes);
  event_changelist_init_(changelist); /* zero it all out. */
}

/** Increase the size of 'changelist' to hold more changes. */
static int
event_changelist_grow(struct event_changelist *changelist)
{
  int new_size;
  struct event_change *new_changes;
  if (changelist->changes_size < 64)
    new_size = 64;
  else
    new_size = changelist->changes_size * 2;

  new_changes = mm_realloc(changelist->changes,
      new_size * sizeof(struct event_change));

  if (EVUTIL_UNLIKELY(new_changes == NULL))
    return (-1);

  changelist->changes = new_changes;
  changelist->changes_size = new_size;

  return (0);
}

/** Return a pointer to the changelist entry for the file descriptor or signal
 * 'fd', whose fdinfo is 'fdinfo'.  If none exists, construct it, setting its
 * old_events field to old_events.
 */
static struct event_change *
event_changelist_get_or_construct(struct event_changelist *changelist,
    evutil_socket_t fd,
    short old_events,
    struct event_changelist_fdinfo *fdinfo)
{
  struct event_change *change;

  if (fdinfo->idxplus1 == 0) {
    int idx;
    EVUTIL_ASSERT(changelist->n_changes <= changelist->changes_size);

    if (changelist->n_changes == changelist->changes_size) {
      if (event_changelist_grow(changelist) < 0)
        return NULL;
    }

    idx = changelist->n_changes++;
    change = &changelist->changes[idx];
    fdinfo->idxplus1 = idx + 1;

    memset(change, 0, sizeof(struct event_change));
    change->fd = fd;
    change->old_events = old_events;
  } else {
    change = &changelist->changes[fdinfo->idxplus1 - 1];
    EVUTIL_ASSERT(change->fd == fd);
  }
  return change;
}

int
event_changelist_add_(struct event_base *base, evutil_socket_t fd, short old, short events,
    void *p)
{
  struct event_changelist *changelist = &base->changelist;
  struct event_changelist_fdinfo *fdinfo = p;
  struct event_change *change;
  ev_uint8_t evchange = EV_CHANGE_ADD | (events & (EV_ET|EV_PERSIST|EV_SIGNAL));

  event_changelist_check(base);

  change = event_changelist_get_or_construct(changelist, fd, old, fdinfo);
  if (!change)
    return -1;

  /* An add replaces any previous delete, but doesn't result in a no-op,
   * since the delete might fail (because the fd had been closed since
   * the last add, for instance. */

  if (events & (EV_READ|EV_SIGNAL))
    change->read_change = evchange;
  if (events & EV_WRITE)
    change->write_change = evchange;
  if (events & EV_CLOSED)
    change->close_change = evchange;

  event_changelist_check(base);
  return (0);
}

int
event_changelist_del_(struct event_base *base, evutil_socket_t fd, short old, short events,
    void *p)
{
  struct event_changelist *changelist = &base->changelist;
  struct event_changelist_fdinfo *fdinfo = p;
  struct event_change *change;
  ev_uint8_t del = EV_CHANGE_DEL | (events & EV_ET);

  event_changelist_check(base);
  change = event_changelist_get_or_construct(changelist, fd, old, fdinfo);
  event_changelist_check(base);
  if (!change)
    return -1;

  /* A delete on an event set that doesn't contain the event to be
     deleted produces a no-op.  This effectively emoves any previous
     uncommitted add, rather than replacing it: on those platforms where
     "add, delete, dispatch" is not the same as "no-op, dispatch", we
     want the no-op behavior.

     If we have a no-op item, we could remove it from the list
     entirely, but really there's not much point: skipping the no-op
     change when we do the dispatch later is far cheaper than rejuggling
     the array now.

     As this stands, it also lets through deletions of events that are
     not currently set.
   */

  if (events & (EV_READ|EV_SIGNAL)) {
    if (!(change->old_events & (EV_READ | EV_SIGNAL)))
      change->read_change = 0;
    else
      change->read_change = del;
  }
  if (events & EV_WRITE) {
    if (!(change->old_events & EV_WRITE))
      change->write_change = 0;
    else
      change->write_change = del;
  }
  if (events & EV_CLOSED) {
    if (!(change->old_events & EV_CLOSED))
      change->close_change = 0;
    else
      change->close_change = del;
  }

  event_changelist_check(base);
  return (0);
}

/* Helper for evmap_check_integrity_: verify that all of the events pending on
 * given fd are set up correctly, and that the nread and nwrite counts on that
 * fd are correct. */
static int
evmap_io_check_integrity_fn(struct event_base *base, evutil_socket_t fd,
    struct evmap_io *io_info, void *arg)
{
  struct event *ev;
  int n_read = 0, n_write = 0, n_close = 0;

  /* First, make sure the list itself isn't corrupt. Otherwise,
   * running LIST_FOREACH could be an exciting adventure. */
  EVUTIL_ASSERT_LIST_OK(&io_info->events, event, ev_io_next);

  LIST_FOREACH(ev, &io_info->events, ev_io_next) {
    EVUTIL_ASSERT(ev->ev_flags & EVLIST_INSERTED);
    EVUTIL_ASSERT(ev->ev_fd == fd);
    EVUTIL_ASSERT(!(ev->ev_events & EV_SIGNAL));
    EVUTIL_ASSERT((ev->ev_events & (EV_READ|EV_WRITE|EV_CLOSED)));
    if (ev->ev_events & EV_READ)
      ++n_read;
    if (ev->ev_events & EV_WRITE)
      ++n_write;
    if (ev->ev_events & EV_CLOSED)
      ++n_close;
  }

  EVUTIL_ASSERT(n_read == io_info->nread);
  EVUTIL_ASSERT(n_write == io_info->nwrite);
  EVUTIL_ASSERT(n_close == io_info->nclose);

  return 0;
}

/* Helper for evmap_check_integrity_: verify that all of the events pending
 * on given signal are set up correctly. */
static int
evmap_signal_check_integrity_fn(struct event_base *base,
    int signum, struct evmap_signal *sig_info, void *arg)
{
  struct event *ev;
  /* First, make sure the list itself isn't corrupt. */
  EVUTIL_ASSERT_LIST_OK(&sig_info->events, event, ev_signal_next);

  LIST_FOREACH(ev, &sig_info->events, ev_io_next) {
    EVUTIL_ASSERT(ev->ev_flags & EVLIST_INSERTED);
    EVUTIL_ASSERT(ev->ev_fd == signum);
    EVUTIL_ASSERT((ev->ev_events & EV_SIGNAL));
    EVUTIL_ASSERT(!(ev->ev_events & (EV_READ|EV_WRITE|EV_CLOSED)));
  }
  return 0;
}

void
evmap_check_integrity_(struct event_base *base)
{
  evmap_io_foreach_fd(base, evmap_io_check_integrity_fn, NULL);
  evmap_signal_foreach_signal(base, evmap_signal_check_integrity_fn, NULL);

  if (base->evsel->add == event_changelist_add_)
    event_changelist_assert_ok(base);
}

/* Helper type for evmap_foreach_event_: Bundles a function to call on every
 * event, and the user-provided void* to use as its third argument. */
struct evmap_foreach_event_helper {
  event_base_foreach_event_cb fn;
  void *arg;
};

/* Helper for evmap_foreach_event_: calls a provided function on every event
 * pending on a given fd.  */
static int
evmap_io_foreach_event_fn(struct event_base *base, evutil_socket_t fd,
    struct evmap_io *io_info, void *arg)
{
  struct evmap_foreach_event_helper *h = arg;
  struct event *ev;
  int r;
  LIST_FOREACH(ev, &io_info->events, ev_io_next) {
    if ((r = h->fn(base, ev, h->arg)))
      return r;
  }
  return 0;
}

/* Helper for evmap_foreach_event_: calls a provided function on every event
 * pending on a given signal.  */
static int
evmap_signal_foreach_event_fn(struct event_base *base, int signum,
    struct evmap_signal *sig_info, void *arg)
{
  struct event *ev;
  struct evmap_foreach_event_helper *h = arg;
  int r;
  LIST_FOREACH(ev, &sig_info->events, ev_signal_next) {
    if ((r = h->fn(base, ev, h->arg)))
      return r;
  }
  return 0;
}

int
evmap_foreach_event_(struct event_base *base,
    event_base_foreach_event_cb fn, void *arg)
{
  struct evmap_foreach_event_helper h;
  int r;
  h.fn = fn;
  h.arg = arg;
  if ((r = evmap_io_foreach_fd(base, evmap_io_foreach_event_fn, &h)))
    return r;
  return evmap_signal_foreach_signal(base, evmap_signal_foreach_event_fn, &h);
}


Coverage Report

Created: 2025-08-03 06:48