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eloop.c

/*
 * Event loop based on select() loop
 * Copyright (c) 2002-2005, Jouni Malinen <jkmaline@cc.hut.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "eloop.h"


struct eloop_sock {
      int sock;
      void *eloop_data;
      void *user_data;
      eloop_sock_handler handler;
};

struct eloop_timeout {
      struct os_time time;
      void *eloop_data;
      void *user_data;
      eloop_timeout_handler handler;
      struct eloop_timeout *next;
};

struct eloop_signal {
      int sig;
      void *user_data;
      eloop_signal_handler handler;
      int signaled;
};

struct eloop_sock_table {
      int count;
      struct eloop_sock *table;
      int changed;
};

struct eloop_data {
      void *user_data;

      int max_sock;

      struct eloop_sock_table readers;
      struct eloop_sock_table writers;
      struct eloop_sock_table exceptions;

      struct eloop_timeout *timeout;

      int signal_count;
      struct eloop_signal *signals;
      int signaled;
      int pending_terminate;

      int terminate;
      int reader_table_changed;
};

static struct eloop_data eloop;


int eloop_init(void *user_data)
{
      os_memset(&eloop, 0, sizeof(eloop));
      eloop.user_data = user_data;
      return 0;
}


static int eloop_sock_table_add_sock(struct eloop_sock_table *table,
                                     int sock, eloop_sock_handler handler,
                                     void *eloop_data, void *user_data)
{
      struct eloop_sock *tmp;

      if (table == NULL)
            return -1;

      tmp = (struct eloop_sock *)
            os_realloc(table->table,
                     (table->count + 1) * sizeof(struct eloop_sock));
      if (tmp == NULL)
            return -1;

      tmp[table->count].sock = sock;
      tmp[table->count].eloop_data = eloop_data;
      tmp[table->count].user_data = user_data;
      tmp[table->count].handler = handler;
      table->count++;
      table->table = tmp;
      if (sock > eloop.max_sock)
            eloop.max_sock = sock;
      table->changed = 1;

      return 0;
}


static void eloop_sock_table_remove_sock(struct eloop_sock_table *table,
                                         int sock)
{
      int i;

      if (table == NULL || table->table == NULL || table->count == 0)
            return;

      for (i = 0; i < table->count; i++) {
            if (table->table[i].sock == sock)
                  break;
      }
      if (i == table->count)
            return;
      if (i != table->count - 1) {
            os_memmove(&table->table[i], &table->table[i + 1],
                     (table->count - i - 1) *
                     sizeof(struct eloop_sock));
      }
      table->count--;
      table->changed = 1;
}


static void eloop_sock_table_set_fds(struct eloop_sock_table *table,
                             fd_set *fds)
{
      int i;

      FD_ZERO(fds);

      if (table->table == NULL)
            return;

      for (i = 0; i < table->count; i++)
            FD_SET(table->table[i].sock, fds);
}


static void eloop_sock_table_dispatch(struct eloop_sock_table *table,
                              fd_set *fds)
{
      int i;

      if (table == NULL || table->table == NULL)
            return;

      table->changed = 0;
      for (i = 0; i < table->count; i++) {
            if (FD_ISSET(table->table[i].sock, fds)) {
                  table->table[i].handler(table->table[i].sock,
                                    table->table[i].eloop_data,
                                    table->table[i].user_data);
                  if (table->changed)
                        break;
            }
      }
}


static void eloop_sock_table_destroy(struct eloop_sock_table *table)
{
      if (table)
            os_free(table->table);
}


int eloop_register_read_sock(int sock, eloop_sock_handler handler,
                       void *eloop_data, void *user_data)
{
      return eloop_register_sock(sock, EVENT_TYPE_READ, handler,
                           eloop_data, user_data);
}


void eloop_unregister_read_sock(int sock)
{
      eloop_unregister_sock(sock, EVENT_TYPE_READ);
}


static struct eloop_sock_table *eloop_get_sock_table(eloop_event_type type)
{
      switch (type) {
      case EVENT_TYPE_READ:
            return &eloop.readers;
      case EVENT_TYPE_WRITE:
            return &eloop.writers;
      case EVENT_TYPE_EXCEPTION:
            return &eloop.exceptions;
      }

      return NULL;
}


int eloop_register_sock(int sock, eloop_event_type type,
                  eloop_sock_handler handler,
                  void *eloop_data, void *user_data)
{
      struct eloop_sock_table *table;

      table = eloop_get_sock_table(type);
      return eloop_sock_table_add_sock(table, sock, handler,
                               eloop_data, user_data);
}


void eloop_unregister_sock(int sock, eloop_event_type type)
{
      struct eloop_sock_table *table;

      table = eloop_get_sock_table(type);
      eloop_sock_table_remove_sock(table, sock);
}


int eloop_register_timeout(unsigned int secs, unsigned int usecs,
                     eloop_timeout_handler handler,
                     void *eloop_data, void *user_data)
{
      struct eloop_timeout *timeout, *tmp, *prev;

      timeout = os_malloc(sizeof(*timeout));
      if (timeout == NULL)
            return -1;
      os_get_time(&timeout->time);
      timeout->time.sec += secs;
      timeout->time.usec += usecs;
      while (timeout->time.usec >= 1000000) {
            timeout->time.sec++;
            timeout->time.usec -= 1000000;
      }
      timeout->eloop_data = eloop_data;
      timeout->user_data = user_data;
      timeout->handler = handler;
      timeout->next = NULL;

      if (eloop.timeout == NULL) {
            eloop.timeout = timeout;
            return 0;
      }

      prev = NULL;
      tmp = eloop.timeout;
      while (tmp != NULL) {
            if (os_time_before(&timeout->time, &tmp->time))
                  break;
            prev = tmp;
            tmp = tmp->next;
      }

      if (prev == NULL) {
            timeout->next = eloop.timeout;
            eloop.timeout = timeout;
      } else {
            timeout->next = prev->next;
            prev->next = timeout;
      }

      return 0;
}


int eloop_cancel_timeout(eloop_timeout_handler handler,
                   void *eloop_data, void *user_data)
{
      struct eloop_timeout *timeout, *prev, *next;
      int removed = 0;

      prev = NULL;
      timeout = eloop.timeout;
      while (timeout != NULL) {
            next = timeout->next;

            if (timeout->handler == handler &&
                (timeout->eloop_data == eloop_data ||
                 eloop_data == ELOOP_ALL_CTX) &&
                (timeout->user_data == user_data ||
                 user_data == ELOOP_ALL_CTX)) {
                  if (prev == NULL)
                        eloop.timeout = next;
                  else
                        prev->next = next;
                  os_free(timeout);
                  removed++;
            } else
                  prev = timeout;

            timeout = next;
      }

      return removed;
}


static void eloop_handle_alarm(int sig)
{
      fprintf(stderr, "eloop: could not process SIGINT or SIGTERM in two "
            "seconds. Looks like there\n"
            "is a bug that ends up in a busy loop that "
            "prevents clean shutdown.\n"
            "Killing program forcefully.\n"
            "sig is %d.\n", sig);
      exit(1);
}


static void eloop_handle_signal(int sig)
{
      int i;

      if ((sig == SIGINT || sig == SIGTERM) && !eloop.pending_terminate) {
            /* Use SIGALRM to break out from potential busy loops that
             * would not allow the program to be killed. */
            eloop.pending_terminate = 1;
            signal(SIGALRM, eloop_handle_alarm);
            alarm(2);
      }

      eloop.signaled++;
      for (i = 0; i < eloop.signal_count; i++) {
            if (eloop.signals[i].sig == sig) {
                  eloop.signals[i].signaled++;
                  break;
            }
      }
}


static void eloop_process_pending_signals(void)
{
      int i;

      if (eloop.signaled == 0)
            return;
      eloop.signaled = 0;

      if (eloop.pending_terminate) {
            alarm(0);
            eloop.pending_terminate = 0;
      }

      for (i = 0; i < eloop.signal_count; i++) {
            if (eloop.signals[i].signaled) {
                  eloop.signals[i].signaled = 0;
                  eloop.signals[i].handler(eloop.signals[i].sig,
                                     eloop.user_data,
                                     eloop.signals[i].user_data);
            }
      }
}


int eloop_register_signal(int sig, eloop_signal_handler handler,
                    void *user_data)
{
      struct eloop_signal *tmp;

      tmp = (struct eloop_signal *)
            os_realloc(eloop.signals,
                     (eloop.signal_count + 1) *
                     sizeof(struct eloop_signal));
      if (tmp == NULL)
            return -1;

      tmp[eloop.signal_count].sig = sig;
      tmp[eloop.signal_count].user_data = user_data;
      tmp[eloop.signal_count].handler = handler;
      tmp[eloop.signal_count].signaled = 0;
      eloop.signal_count++;
      eloop.signals = tmp;
      signal(sig, eloop_handle_signal);

      return 0;
}


int eloop_register_signal_terminate(eloop_signal_handler handler,
                            void *user_data)
{
      int ret = eloop_register_signal(SIGINT, handler, user_data);
      if (ret == 0)
            ret = eloop_register_signal(SIGTERM, handler, user_data);
      return ret;
}


int eloop_register_signal_reconfig(eloop_signal_handler handler,
                           void *user_data)
{
      return eloop_register_signal(SIGHUP, handler, user_data);
}


void eloop_run(void)
{
      fd_set *rfds, *wfds, *efds;
      int res;
      struct timeval _tv;
      struct os_time tv, now;

      rfds = os_malloc(sizeof(*rfds));
      wfds = os_malloc(sizeof(*wfds));
      efds = os_malloc(sizeof(*efds));
      if (rfds == NULL || wfds == NULL || efds == NULL) {
            printf("eloop_run - malloc failed\n");
            goto out;
      }

      while (!eloop.terminate &&
             (eloop.timeout || eloop.readers.count > 0 ||
            eloop.writers.count > 0 || eloop.exceptions.count > 0)) {
            if (eloop.timeout) {
                  os_get_time(&now);
                  if (os_time_before(&now, &eloop.timeout->time))
                        os_time_sub(&eloop.timeout->time, &now, &tv);
                  else
                        tv.sec = tv.usec = 0;
#if 0
                  printf("next timeout in %lu.%06lu sec\n",
                         tv.sec, tv.usec);
#endif
                  _tv.tv_sec = tv.sec;
                  _tv.tv_usec = tv.usec;
            }

            eloop_sock_table_set_fds(&eloop.readers, rfds);
            eloop_sock_table_set_fds(&eloop.writers, wfds);
            eloop_sock_table_set_fds(&eloop.exceptions, efds);
            res = select(eloop.max_sock + 1, rfds, wfds, efds,
                       eloop.timeout ? &_tv : NULL);
            if (res < 0 && errno != EINTR && errno != 0) {
                  perror("select");
                  goto out;
            }
            eloop_process_pending_signals();

            /* check if some registered timeouts have occurred */
            if (eloop.timeout) {
                  struct eloop_timeout *tmp;

                  os_get_time(&now);
                  if (!os_time_before(&now, &eloop.timeout->time)) {
                        tmp = eloop.timeout;
                        eloop.timeout = eloop.timeout->next;
                        tmp->handler(tmp->eloop_data,
                                   tmp->user_data);
                        os_free(tmp);
                  }

            }

            if (res <= 0)
                  continue;

            eloop_sock_table_dispatch(&eloop.readers, rfds);
            eloop_sock_table_dispatch(&eloop.writers, wfds);
            eloop_sock_table_dispatch(&eloop.exceptions, efds);
      }

out:
      os_free(rfds);
      os_free(wfds);
      os_free(efds);
}


void eloop_terminate(void)
{
      eloop.terminate = 1;
}


void eloop_destroy(void)
{
      struct eloop_timeout *timeout, *prev;

      timeout = eloop.timeout;
      while (timeout != NULL) {
            prev = timeout;
            timeout = timeout->next;
            os_free(prev);
      }
      eloop_sock_table_destroy(&eloop.readers);
      eloop_sock_table_destroy(&eloop.writers);
      eloop_sock_table_destroy(&eloop.exceptions);
      os_free(eloop.signals);
}


int eloop_terminated(void)
{
      return eloop.terminate;
}


void eloop_wait_for_read_sock(int sock)
{
      fd_set rfds;

      if (sock < 0)
            return;

      FD_ZERO(&rfds);
      FD_SET(sock, &rfds);
      select(sock + 1, &rfds, NULL, NULL, NULL);
}


void * eloop_get_user_data(void)
{
      return eloop.user_data;
}

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