src/lxc/mainloop.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <dlezcano at fr.ibm.com>
   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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <stdlib.h>
  26 #include <errno.h>
  27 #include <unistd.h>
  28 #include <sys/epoll.h>
  29
  30 #include "mainloop.h"
  31
  32 struct mainloop_handler {
  33         lxc_mainloop_callback_t callback;
  34         int fd;
  35         void *data;
  36 };
  37
  38 #define MAX_EVENTS 10
  39
  40 int lxc_mainloop(struct lxc_epoll_descr *descr)
  41 {
  42         int i, nfds;
  43         struct mainloop_handler *handler;
  44         struct epoll_event events[MAX_EVENTS];
  45
  46         for (;;) {
  47
  48                 nfds = epoll_wait(descr->epfd, events, MAX_EVENTS, -1);
  49                 if (nfds < 0) {
  50                         if (errno == EINTR)
  51                                 continue;
  52                         return -1;
  53                 }
  54
  55                 for (i = 0; i < nfds; i++) {
  56                         handler =
  57                                 (struct mainloop_handler *) events[i].data.ptr;
  58
  59                         /* If the handler returns a positive value, exit
  60                            the mainloop */
  61                         if (handler->callback(handler->fd, handler->data,
  62                                               descr) > 0)
  63                                 return 0;
  64                 }
  65
  66                 if (lxc_list_empty(&descr->handlers))
  67                         return 0;
  68         }
  69 }
  70
  71 int lxc_mainloop_add_handler(struct lxc_epoll_descr *descr, int fd,
  72                              lxc_mainloop_callback_t callback, void *data)
  73 {
  74         struct epoll_event ev;
  75         struct mainloop_handler *handler;
  76         struct lxc_list *item;
  77
  78         handler = malloc(sizeof(*handler));
  79         if (!handler)
  80                 return -1;
  81
  82         handler->callback = callback;
  83         handler->fd = fd;
  84         handler->data = data;
  85
  86         ev.events = EPOLLIN;
  87         ev.data.ptr = handler;
  88
  89         if (epoll_ctl(descr->epfd, EPOLL_CTL_ADD, fd, &ev) < 0)
  90                 goto out_free_handler;
  91
  92         item = malloc(sizeof(*item));
  93         if (!item)
  94                 goto out_free_handler;
  95
  96         item->elem = handler;
  97         lxc_list_add(&descr->handlers, item);
  98         return 0;
  99
 100 out_free_handler:
 101         free(handler);
 102         return -1;
 103 }
 104
 105 int lxc_mainloop_del_handler(struct lxc_epoll_descr *descr, int fd)
 106 {
 107         struct mainloop_handler *handler;
 108         struct lxc_list *iterator;
 109
 110         lxc_list_for_each(iterator, &descr->handlers) {
 111                 handler = iterator->elem;
 112
 113                 if (handler->fd == fd) {
 114                         /* found */
 115                         if (epoll_ctl(descr->epfd, EPOLL_CTL_DEL, fd, NULL))
 116                                 return -1;
 117
 118                         lxc_list_del(iterator);
 119                         free(iterator->elem);
 120                         free(iterator);
 121                         return 0;
 122                 }
 123         }
 124
 125         return -1;
 126 }
 127
 128 int lxc_mainloop_open(struct lxc_epoll_descr *descr)
 129 {
 130         /* hint value passed to epoll create */
 131         descr->epfd = epoll_create(2);
 132         if (descr->epfd < 0)
 133                 return -1;
 134
 135         lxc_list_init(&descr->handlers);
 136         return 0;
 137 }
 138
 139 int lxc_mainloop_close(struct lxc_epoll_descr *descr)
 140 {
 141         struct lxc_list *iterator, *next;
 142
 143         iterator = descr->handlers.next;
 144         while (iterator != &descr->handlers) {
 145                 next = iterator->next;
 146
 147                 lxc_list_del(iterator);
 148                 free(iterator->elem);
 149                 free(iterator);
 150                 iterator = next;
 151         }
 152
 153         return close(descr->epfd);
 154 }
 155