libev/ev.c

/*
 * libev event processing core, watcher management
 *
 * Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 COPYRIGHT
 * OWNER OR CONTRIBUTORS 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.
 */

#ifdef __cplusplus
extern "C" {
#endif

#ifndef EV_STANDALONE
# include "config.h"

# if HAVE_CLOCK_GETTIME
#  ifndef EV_USE_MONOTONIC
#   define EV_USE_MONOTONIC 1
#  endif
#  ifndef EV_USE_REALTIME
#   define EV_USE_REALTIME  1
#  endif
# endif

# if HAVE_SELECT && HAVE_SYS_SELECT_H && !defined (EV_USE_SELECT)
#  define EV_USE_SELECT 1
# endif

# if HAVE_POLL && HAVE_POLL_H && !defined (EV_USE_POLL)
#  define EV_USE_POLL 1
# endif

# if HAVE_EPOLL_CTL && HAVE_SYS_EPOLL_H && !defined (EV_USE_EPOLL)
#  define EV_USE_EPOLL 1
# endif

# if HAVE_KQUEUE && HAVE_SYS_EVENT_H && HAVE_SYS_QUEUE_H && !defined (EV_USE_KQUEUE)
#  define EV_USE_KQUEUE 1
# endif

#endif

#include <math.h>
#include <stdlib.h>
#include <fcntl.h>
#include <stddef.h>

#include <stdio.h>

#include <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <time.h>

#include <signal.h>

#ifndef WIN32
# include <unistd.h>
# include <sys/time.h>
# include <sys/wait.h>
#endif
/**/

#ifndef EV_USE_MONOTONIC
# define EV_USE_MONOTONIC 1
#endif

#ifndef EV_USE_SELECT
# define EV_USE_SELECT 1
#endif

#ifndef EV_USE_POLL
# define EV_USE_POLL 0 /* poll is usually slower than select, and not as well tested */
#endif

#ifndef EV_USE_EPOLL
# define EV_USE_EPOLL 0
#endif

#ifndef EV_USE_KQUEUE
# define EV_USE_KQUEUE 0
#endif

#ifndef EV_USE_WIN32
# ifdef WIN32
#  define EV_USE_WIN32 0 /* it does not exist, use select */
#  undef EV_USE_SELECT
#  define EV_USE_SELECT 1
# else
#  define EV_USE_WIN32 0
# endif
#endif

#ifndef EV_USE_REALTIME
# define EV_USE_REALTIME 1
#endif

/**/

#ifndef CLOCK_MONOTONIC
# undef EV_USE_MONOTONIC
# define EV_USE_MONOTONIC 0
#endif

#ifndef CLOCK_REALTIME
# undef EV_USE_REALTIME
# define EV_USE_REALTIME 0
#endif

/**/

#define MIN_TIMEJUMP  1. /* minimum timejump that gets detected (if monotonic clock available) */
#define MAX_BLOCKTIME 59.731 /* never wait longer than this time (to detect time jumps) */
#define PID_HASHSIZE  16 /* size of pid hash table, must be power of two */
/*#define CLEANUP_INTERVAL 300. /* how often to try to free memory and re-check fds */

#ifdef EV_H
# include EV_H
#else
# include "ev.h"
#endif

#if __GNUC__ >= 3
# define expect(expr,value)         __builtin_expect ((expr),(value))
# define inline                     inline
#else
# define expect(expr,value)         (expr)
# define inline                     static
#endif

#define expect_false(expr) expect ((expr) != 0, 0)
#define expect_true(expr)  expect ((expr) != 0, 1)

#define NUMPRI    (EV_MAXPRI - EV_MINPRI + 1)
#define ABSPRI(w) ((w)->priority - EV_MINPRI)

typedef struct ev_watcher *W;
typedef struct ev_watcher_list *WL;
typedef struct ev_watcher_time *WT;

static int have_monotonic; /* did clock_gettime (CLOCK_MONOTONIC) work? */

#ifdef WIN32
# include "ev_win32.c"
#endif

/*****************************************************************************/

static void (*syserr_cb)(const char *msg);

void ev_set_syserr_cb (void (*cb)(const char *msg))
{
  syserr_cb = cb;
}

static void
syserr (const char *msg)
{
  if (!msg)
    msg = "(libev) system error";

  if (syserr_cb)
    syserr_cb (msg);
  else
    {
      perror (msg);
      abort ();
    }
}

static void *(*alloc)(void *ptr, long size);

void ev_set_allocator (void *(*cb)(void *ptr, long size))
{
  alloc = cb;
}

static void *
ev_realloc (void *ptr, long size)
{
  ptr = alloc ? alloc (ptr, size) : realloc (ptr, size);

  if (!ptr && size)
    {
      fprintf (stderr, "libev: cannot allocate %ld bytes, aborting.", size);
      abort ();
    }

  return ptr;
}

#define ev_malloc(size) ev_realloc (0, (size))
#define ev_free(ptr)    ev_realloc ((ptr), 0)

/*****************************************************************************/

typedef struct
{
  WL head;
  unsigned char events;
  unsigned char reify;
} ANFD;

typedef struct
{
  W w;
  int events;
} ANPENDING;

#if EV_MULTIPLICITY

  struct ev_loop
  {
    ev_tstamp ev_rt_now;
    #define ev_rt_now ((loop)->ev_rt_now)
    #define VAR(name,decl) decl;
      #include "ev_vars.h"
    #undef VAR
  };
  #include "ev_wrap.h"

  struct ev_loop default_loop_struct;
  static struct ev_loop *default_loop;

#else

  ev_tstamp ev_rt_now;
  #define VAR(name,decl) static decl;
    #include "ev_vars.h"
  #undef VAR

  static int default_loop;

#endif

/*****************************************************************************/

ev_tstamp
ev_time (void)
{
#if EV_USE_REALTIME
  struct timespec ts;
  clock_gettime (CLOCK_REALTIME, &ts);
  return ts.tv_sec + ts.tv_nsec * 1e-9;
#else
  struct timeval tv;
  gettimeofday (&tv, 0);
  return tv.tv_sec + tv.tv_usec * 1e-6;
#endif
}

inline ev_tstamp
get_clock (void)
{
#if EV_USE_MONOTONIC
  if (expect_true (have_monotonic))
    {
      struct timespec ts;
      clock_gettime (CLOCK_MONOTONIC, &ts);
      return ts.tv_sec + ts.tv_nsec * 1e-9;
    }
#endif

  return ev_time ();
}

#if EV_MULTIPLICITY
ev_tstamp
ev_now (EV_P)
{
  return ev_rt_now;
}
#endif

#define array_roundsize(type,n) ((n) | 4 & ~3)

#define array_needsize(type,base,cur,cnt,init)			\
  if (expect_false ((cnt) > cur))				\
    {								\
      int newcnt = cur;						\
      do							\
        {							\
          newcnt = array_roundsize (type, newcnt << 1);		\
        }							\
      while ((cnt) > newcnt);					\
      								\
      base = (type *)ev_realloc (base, sizeof (type) * (newcnt));\
      init (base + cur, newcnt - cur);				\
      cur = newcnt;						\
    }

#define array_slim(type,stem)					\
  if (stem ## max < array_roundsize (stem ## cnt >> 2))		\
    {								\
      stem ## max = array_roundsize (stem ## cnt >> 1);		\
      base = (type *)ev_realloc (base, sizeof (type) * (stem ## max));\
      fprintf (stderr, "slimmed down " # stem " to %d\n", stem ## max);/*D*/\
    }

/* microsoft's pseudo-c is quite far from C as the rest of the world and the standard knows it */
/* bringing us everlasting joy in form of stupid extra macros that are not required in C */
#define array_free_microshit(stem) \
  ev_free (stem ## s); stem ## cnt = stem ## max = 0;

#define array_free(stem, idx) \
  ev_free (stem ## s idx); stem ## cnt idx = stem ## max idx = 0;

/*****************************************************************************/

static void
anfds_init (ANFD *base, int count)
{
  while (count--)
    {
      base->head   = 0;
      base->events = EV_NONE;
      base->reify  = 0;

      ++base;
    }
}

void
ev_feed_event (EV_P_ void *w, int revents)
{
  W w_ = (W)w;

  if (w_->pending)
    {
      pendings [ABSPRI (w_)][w_->pending - 1].events |= revents;
      return;
    }

  w_->pending = ++pendingcnt [ABSPRI (w_)];
  array_needsize (ANPENDING, pendings [ABSPRI (w_)], pendingmax [ABSPRI (w_)], pendingcnt [ABSPRI (w_)], (void));
  pendings [ABSPRI (w_)][w_->pending - 1].w      = w_;
  pendings [ABSPRI (w_)][w_->pending - 1].events = revents;
}

static void
queue_events (EV_P_ W *events, int eventcnt, int type)
{
  int i;

  for (i = 0; i < eventcnt; ++i)
    ev_feed_event (EV_A_ events [i], type);
}

inline void
fd_event (EV_P_ int fd, int revents)
{
  ANFD *anfd = anfds + fd;
  struct ev_io *w;

  for (w = (struct ev_io *)anfd->head; w; w = (struct ev_io *)((WL)w)->next)
    {
      int ev = w->events & revents;

      if (ev)
        ev_feed_event (EV_A_ (W)w, ev);
    }
}

void
ev_feed_fd_event (EV_P_ int fd, int revents)
{
  fd_event (EV_A_ fd, revents);
}

/*****************************************************************************/

static void
fd_reify (EV_P)
{
  int i;

  for (i = 0; i < fdchangecnt; ++i)
    {
      int fd = fdchanges [i];
      ANFD *anfd = anfds + fd;
      struct ev_io *w;

      int events = 0;

      for (w = (struct ev_io *)anfd->head; w; w = (struct ev_io *)((WL)w)->next)
        events |= w->events;

      anfd->reify = 0;

      method_modify (EV_A_ fd, anfd->events, events);
      anfd->events = events;
    }

  fdchangecnt = 0;
}

static void
fd_change (EV_P_ int fd)
{
  if (anfds [fd].reify)
    return;

  anfds [fd].reify = 1;

  ++fdchangecnt;
  array_needsize (int, fdchanges, fdchangemax, fdchangecnt, (void));
  fdchanges [fdchangecnt - 1] = fd;
}

static void
fd_kill (EV_P_ int fd)
{
  struct ev_io *w;

  while ((w = (struct ev_io *)anfds [fd].head))
    {
      ev_io_stop (EV_A_ w);
      ev_feed_event (EV_A_ (W)w, EV_ERROR | EV_READ | EV_WRITE);
    }
}

static int
fd_valid (int fd)
{
#ifdef WIN32
  return !!win32_get_osfhandle (fd);
#else
  return fcntl (fd, F_GETFD) != -1;
#endif
}

/* called on EBADF to verify fds */
static void
fd_ebadf (EV_P)
{
  int fd;

  for (fd = 0; fd < anfdmax; ++fd)
    if (anfds [fd].events)
      if (!fd_valid (fd) == -1 && errno == EBADF)
        fd_kill (EV_A_ fd);
}

/* called on ENOMEM in select/poll to kill some fds and retry */
static void
fd_enomem (EV_P)
{
  int fd;

  for (fd = anfdmax; fd--; )
    if (anfds [fd].events)
      {
        fd_kill (EV_A_ fd);
        return;
      }
}

/* usually called after fork if method needs to re-arm all fds from scratch */
static void
fd_rearm_all (EV_P)
{
  int fd;

  /* this should be highly optimised to not do anything but set a flag */
  for (fd = 0; fd < anfdmax; ++fd)
    if (anfds [fd].events)
      {
        anfds [fd].events = 0;
        fd_change (EV_A_ fd);
      }
}

/*****************************************************************************/

static void
upheap (WT *heap, int k)
{
  WT w = heap [k];

  while (k && heap [k >> 1]->at > w->at)
    {
      heap [k] = heap [k >> 1];
      ((W)heap [k])->active = k + 1;
      k >>= 1;
    }

  heap [k] = w;
  ((W)heap [k])->active = k + 1;

}

static void
downheap (WT *heap, int N, int k)
{
  WT w = heap [k];

  while (k < (N >> 1))
    {
      int j = k << 1;

      if (j + 1 < N && heap [j]->at > heap [j + 1]->at)
        ++j;

      if (w->at <= heap [j]->at)
        break;

      heap [k] = heap [j];
      ((W)heap [k])->active = k + 1;
      k = j;
    }

  heap [k] = w;
  ((W)heap [k])->active = k + 1;
}

inline void
adjustheap (WT *heap, int N, int k)
{
  upheap (heap, k);
  downheap (heap, N, k);
}

/*****************************************************************************/

typedef struct
{
  WL head;
  sig_atomic_t volatile gotsig;
} ANSIG;

static ANSIG *signals;
static int signalmax;

static int sigpipe [2];
static sig_atomic_t volatile gotsig;
static struct ev_io sigev;

static void
signals_init (ANSIG *base, int count)
{
  while (count--)
    {
      base->head   = 0;
      base->gotsig = 0;

      ++base;
    }
}

static void
sighandler (int signum)
{
#if WIN32
  signal (signum, sighandler);
#endif

  signals [signum - 1].gotsig = 1;

  if (!gotsig)
    {
      int old_errno = errno;
      gotsig = 1;
#ifdef WIN32
      send (sigpipe [1], &signum, 1, MSG_DONTWAIT);
#else
      write (sigpipe [1], &signum, 1);
#endif
      errno = old_errno;
    }
}

void
ev_feed_signal_event (EV_P_ int signum)
{
  WL w;

#if EV_MULTIPLICITY
  assert (("feeding signal events is only supported in the default loop", loop == default_loop));
#endif

  --signum;

  if (signum < 0 || signum >= signalmax)
    return;

  signals [signum].gotsig = 0;

  for (w = signals [signum].head; w; w = w->next)
    ev_feed_event (EV_A_ (W)w, EV_SIGNAL);
}

static void
sigcb (EV_P_ struct ev_io *iow, int revents)
{
  int signum;

#ifdef WIN32
  recv (sigpipe [0], &revents, 1, MSG_DONTWAIT);
#else
  read (sigpipe [0], &revents, 1);
#endif
  gotsig = 0;

  for (signum = signalmax; signum--; )
    if (signals [signum].gotsig)
      ev_feed_signal_event (EV_A_ signum + 1);
}

static void
siginit (EV_P)
{
#ifndef WIN32
  fcntl (sigpipe [0], F_SETFD, FD_CLOEXEC);
  fcntl (sigpipe [1], F_SETFD, FD_CLOEXEC);

  /* rather than sort out wether we really need nb, set it */
  fcntl (sigpipe [0], F_SETFL, O_NONBLOCK);
  fcntl (sigpipe [1], F_SETFL, O_NONBLOCK);
#endif

  ev_io_set (&sigev, sigpipe [0], EV_READ);
  ev_io_start (EV_A_ &sigev);
  ev_unref (EV_A); /* child watcher should not keep loop alive */
}

/*****************************************************************************/

static struct ev_child *childs [PID_HASHSIZE];

#ifndef WIN32

static struct ev_signal childev;

#ifndef WCONTINUED
# define WCONTINUED 0
#endif

static void
child_reap (EV_P_ struct ev_signal *sw, int chain, int pid, int status)
{
  struct ev_child *w;

  for (w = (struct ev_child *)childs [chain & (PID_HASHSIZE - 1)]; w; w = (struct ev_child *)((WL)w)->next)
    if (w->pid == pid || !w->pid)
      {
        ev_priority (w) = ev_priority (sw); /* need to do it *now* */
        w->rpid         = pid;
        w->rstatus      = status;
        ev_feed_event (EV_A_ (W)w, EV_CHILD);
      }
}

static void
childcb (EV_P_ struct ev_signal *sw, int revents)
{
  int pid, status;

  if (0 < (pid = waitpid (-1, &status, WNOHANG | WUNTRACED | WCONTINUED)))
    {
      /* make sure we are called again until all childs have been reaped */
      ev_feed_event (EV_A_ (W)sw, EV_SIGNAL);

      child_reap (EV_A_ sw, pid, pid, status);
      child_reap (EV_A_ sw,   0, pid, status); /* this might trigger a watcher twice, but event catches that */
    }
}

#endif

/*****************************************************************************/

#if EV_USE_KQUEUE
# include "ev_kqueue.c"
#endif
#if EV_USE_EPOLL
# include "ev_epoll.c"
#endif
#if EV_USE_POLL
# include "ev_poll.c"
#endif
#if EV_USE_SELECT
# include "ev_select.c"
#endif

int
ev_version_major (void)
{
  return EV_VERSION_MAJOR;
}

int
ev_version_minor (void)
{
  return EV_VERSION_MINOR;
}

/* return true if we are running with elevated privileges and should ignore env variables */
static int
enable_secure (void)
{
#ifdef WIN32
  return 0;
#else
  return getuid () != geteuid ()
      || getgid () != getegid ();