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 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/epoll.h>
  33 #include <unistd.h>
  34
  35 #include "config.h"
  36 #include "mainloop.h"
  37
  38 struct mainloop_handler {
  39         lxc_mainloop_callback_t callback;
  40         int fd;
  41         void *data;
  42 };
  43
  44 #define MAX_EVENTS 10
  45
  46 int lxc_mainloop(struct lxc_epoll_descr *descr, int timeout_ms)
  47 {
  48         int i, nfds, ret;
  49         struct mainloop_handler *handler;
  50         struct epoll_event events[MAX_EVENTS];
  51
  52         for (;;) {
  53                 nfds = epoll_wait(descr->epfd, events, MAX_EVENTS, timeout_ms);
  54                 if (nfds < 0) {
  55                         if (errno == EINTR)
  56                                 continue;
  57
  58                         return -1;
  59                 }
  60
  61                 for (i = 0; i < nfds; i++) {
  62                         handler = events[i].data.ptr;
  63
  64                         /* If the handler returns a positive value, exit the
  65                          * mainloop.
  66                          */
  67                         ret = handler->callback(handler->fd, events[i].events,
  68                                                 handler->data, descr);
  69                         if (ret == LXC_MAINLOOP_CLOSE)
  70                                 return 0;
  71                 }
  72
  73                 if (nfds == 0)
  74                         return 0;
  75
  76                 if (lxc_list_empty(&descr->handlers))
  77                         return 0;
  78         }
  79 }
  80
  81 int lxc_mainloop_add_handler(struct lxc_epoll_descr *descr, int fd,
  82                              lxc_mainloop_callback_t callback, void *data)
  83 {
  84         struct epoll_event ev;
  85         struct mainloop_handler *handler;
  86         struct lxc_list *item;
  87
  88         handler = malloc(sizeof(*handler));
  89         if (!handler)
  90                 return -1;
  91
  92         handler->callback = callback;
  93         handler->fd = fd;
  94         handler->data = data;
  95
  96         ev.events = EPOLLIN;
  97         ev.data.ptr = handler;
  98
  99         if (epoll_ctl(descr->epfd, EPOLL_CTL_ADD, fd, &ev) < 0)
 100                 goto out_free_handler;
 101
 102         item = malloc(sizeof(*item));
 103         if (!item)
 104                 goto out_free_handler;
 105
 106         item->elem = handler;
 107         lxc_list_add(&descr->handlers, item);
 108         return 0;
 109
 110 out_free_handler:
 111         free(handler);
 112         return -1;
 113 }
 114
 115 int lxc_mainloop_del_handler(struct lxc_epoll_descr *descr, int fd)
 116 {
 117         struct mainloop_handler *handler;
 118         struct lxc_list *iterator;
 119
 120         lxc_list_for_each(iterator, &descr->handlers) {
 121                 handler = iterator->elem;
 122
 123                 if (handler->fd == fd) {
 124                         /* found */
 125                         if (epoll_ctl(descr->epfd, EPOLL_CTL_DEL, fd, NULL))
 126                                 return -1;
 127
 128                         lxc_list_del(iterator);
 129                         free(iterator->elem);
 130                         free(iterator);
 131                         return 0;
 132                 }
 133         }
 134
 135         return -1;
 136 }
 137
 138 int lxc_mainloop_open(struct lxc_epoll_descr *descr)
 139 {
 140         /* hint value passed to epoll create */
 141         descr->epfd = epoll_create1(EPOLL_CLOEXEC);
 142         if (descr->epfd < 0)
 143                 return -1;
 144
 145         lxc_list_init(&descr->handlers);
 146         return 0;
 147 }
 148
 149 int lxc_mainloop_close(struct lxc_epoll_descr *descr)
 150 {
 151         struct lxc_list *iterator, *next;
 152
 153         iterator = descr->handlers.next;
 154         while (iterator != &descr->handlers) {
 155                 next = iterator->next;
 156
 157                 lxc_list_del(iterator);
 158                 free(iterator->elem);
 159                 free(iterator);
 160                 iterator = next;
 161         }
 162
 163         if (descr->epfd >= 0)
 164                 return close(descr->epfd);
 165
 166         return 0;
 167 }