tor-browser

evmap.c (29011B)

---

/*
* 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, NULL)
	    == -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, 0, EV_SIGNAL, NULL) == -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 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);
}