src/lxc/mainloop.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #include <sys/epoll.h>
  31
  32 #include "mainloop.h"
  33
  34 struct mainloop_handler {
  35         lxc_mainloop_callback_t callback;
  36         int fd;
  37         void *data;
  38 };
  39
  40 #define MAX_EVENTS 10
  41
  42 int lxc_mainloop(struct lxc_epoll_descr *descr, int timeout_ms)
  43 {
  44         int i, nfds, ret;
  45         struct mainloop_handler *handler;
  46         struct epoll_event events[MAX_EVENTS];
  47
  48         for (;;) {
  49                 nfds = epoll_wait(descr->epfd, events, MAX_EVENTS, timeout_ms);
  50                 if (nfds < 0) {
  51                         if (errno == EINTR)
  52                                 continue;
  53
  54                         return -1;
  55                 }
  56
  57                 for (i = 0; i < nfds; i++) {
  58                         handler = events[i].data.ptr;
  59
  60                         /* If the handler returns a positive value, exit the
  61                          * mainloop.
  62                          */
  63                         ret = handler->callback(handler->fd, events[i].events,
  64                                                 handler->data, descr);
  65                         if (ret == LXC_MAINLOOP_CLOSE)
  66                                 return 0;
  67                 }
  68
  69                 if (nfds == 0)
  70                         return 0;
  71
  72                 if (lxc_list_empty(&descr->handlers))
  73                         return 0;
  74         }
  75 }
  76
  77 int lxc_mainloop_add_handler(struct lxc_epoll_descr *descr, int fd,
  78                              lxc_mainloop_callback_t callback, void *data)
  79 {
  80         struct epoll_event ev;
  81         struct mainloop_handler *handler;
  82         struct lxc_list *item;
  83
  84         handler = malloc(sizeof(*handler));
  85         if (!handler)
  86                 return -1;
  87
  88         handler->callback = callback;
  89         handler->fd = fd;
  90         handler->data = data;
  91
  92         ev.events = EPOLLIN;
  93         ev.data.ptr = handler;
  94
  95         if (epoll_ctl(descr->epfd, EPOLL_CTL_ADD, fd, &ev) < 0)
  96                 goto out_free_handler;
  97
  98         item = malloc(sizeof(*item));
  99         if (!item)
 100                 goto out_free_handler;
 101
 102         item->elem = handler;
 103         lxc_list_add(&descr->handlers, item);
 104         return 0;
 105
 106 out_free_handler:
 107         free(handler);
 108         return -1;
 109 }
 110
 111 int lxc_mainloop_del_handler(struct lxc_epoll_descr *descr, int fd)
 112 {
 113         struct mainloop_handler *handler;
 114         struct lxc_list *iterator;
 115
 116         lxc_list_for_each(iterator, &descr->handlers) {
 117                 handler = iterator->elem;
 118
 119                 if (handler->fd == fd) {
 120                         /* found */
 121                         if (epoll_ctl(descr->epfd, EPOLL_CTL_DEL, fd, NULL))
 122                                 return -1;
 123
 124                         lxc_list_del(iterator);
 125                         free(iterator->elem);
 126                         free(iterator);
 127                         return 0;
 128                 }
 129         }
 130
 131         return -1;
 132 }
 133
 134 int lxc_mainloop_open(struct lxc_epoll_descr *descr)
 135 {
 136         /* hint value passed to epoll create */
 137         descr->epfd = epoll_create(2);
 138         if (descr->epfd < 0)
 139                 return -1;
 140
 141         if (fcntl(descr->epfd, F_SETFD, FD_CLOEXEC)) {
 142                 close(descr->epfd);
 143                 return -1;
 144         }
 145
 146         lxc_list_init(&descr->handlers);
 147         return 0;
 148 }
 149
 150 int lxc_mainloop_close(struct lxc_epoll_descr *descr)
 151 {
 152         struct lxc_list *iterator, *next;
 153
 154         iterator = descr->handlers.next;
 155         while (iterator != &descr->handlers) {
 156                 next = iterator->next;
 157
 158                 lxc_list_del(iterator);
 159                 free(iterator->elem);
 160                 free(iterator);
 161                 iterator = next;
 162         }
 163
 164         return close(descr->epfd);
 165 }