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 #include <stdio.h>
  24 #include <string.h>
  25 #include <stdlib.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <sys/epoll.h>
  30
  31 #include "mainloop.h"
  32
  33 struct mainloop_handler {
  34         lxc_mainloop_callback_t callback;
  35         int fd;
  36         void *data;
  37 };
  38
  39 #define MAX_EVENTS 10
  40
  41 int lxc_mainloop(struct lxc_epoll_descr *descr, int timeout_ms)
  42 {
  43         int i, nfds;
  44         struct mainloop_handler *handler;
  45         struct epoll_event events[MAX_EVENTS];
  46
  47         for (;;) {
  48
  49                 nfds = epoll_wait(descr->epfd, events, MAX_EVENTS, timeout_ms);
  50                 if (nfds < 0) {
  51                         if (errno == EINTR)
  52                                 continue;
  53                         return -1;
  54                 }
  55
  56                 for (i = 0; i < nfds; i++) {
  57                         handler =
  58                                 (struct mainloop_handler *) events[i].data.ptr;
  59
  60                         /* If the handler returns a positive value, exit
  61                            the mainloop */
  62                         if (handler->callback(handler->fd, handler->data,
  63                                               descr) > 0)
  64                                 return 0;
  65                 }
  66
  67                 if (nfds == 0 && timeout_ms != 0)
  68                         return 0;
  69
  70                 if (lxc_list_empty(&descr->handlers))
  71                         return 0;
  72         }
  73 }
  74
  75 int lxc_mainloop_add_handler(struct lxc_epoll_descr *descr, int fd,
  76                              lxc_mainloop_callback_t callback, void *data)
  77 {
  78         struct epoll_event ev;
  79         struct mainloop_handler *handler;
  80         struct lxc_list *item;
  81
  82         handler = malloc(sizeof(*handler));
  83         if (!handler)
  84                 return -1;
  85
  86         handler->callback = callback;
  87         handler->fd = fd;
  88         handler->data = data;
  89
  90         ev.events = EPOLLIN;
  91         ev.data.ptr = handler;
  92
  93         if (epoll_ctl(descr->epfd, EPOLL_CTL_ADD, fd, &ev) < 0)
  94                 goto out_free_handler;
  95
  96         item = malloc(sizeof(*item));
  97         if (!item)
  98                 goto out_free_handler;
  99
 100         item->elem = handler;
 101         lxc_list_add(&descr->handlers, item);
 102         return 0;
 103
 104 out_free_handler:
 105         free(handler);
 106         return -1;
 107 }
 108
 109 int lxc_mainloop_del_handler(struct lxc_epoll_descr *descr, int fd)
 110 {
 111         struct mainloop_handler *handler;
 112         struct lxc_list *iterator;
 113
 114         lxc_list_for_each(iterator, &descr->handlers) {
 115                 handler = iterator->elem;
 116
 117                 if (handler->fd == fd) {
 118                         /* found */
 119                         if (epoll_ctl(descr->epfd, EPOLL_CTL_DEL, fd, NULL))
 120                                 return -1;
 121
 122                         lxc_list_del(iterator);
 123                         free(iterator->elem);
 124                         free(iterator);
 125                         return 0;
 126                 }
 127         }
 128
 129         return -1;
 130 }
 131
 132 int lxc_mainloop_open(struct lxc_epoll_descr *descr)
 133 {
 134         /* hint value passed to epoll create */
 135         descr->epfd = epoll_create(2);
 136         if (descr->epfd < 0)
 137                 return -1;
 138
 139         if (fcntl(descr->epfd, F_SETFD, FD_CLOEXEC)) {
 140                 close(descr->epfd);
 141                 return -1;
 142         }
 143
 144         lxc_list_init(&descr->handlers);
 145         return 0;
 146 }
 147
 148 int lxc_mainloop_close(struct lxc_epoll_descr *descr)
 149 {
 150         struct lxc_list *iterator, *next;
 151
 152         iterator = descr->handlers.next;
 153         while (iterator != &descr->handlers) {
 154                 next = iterator->next;
 155
 156                 lxc_list_del(iterator);
 157                 free(iterator->elem);
 158                 free(iterator);
 159                 iterator = next;
 160         }
 161
 162         return close(descr->epfd);
 163 }
 164