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 <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)
  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, -1);
  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 (lxc_list_empty(&descr->handlers))
  68                         return 0;
  69         }
  70 }
  71
  72 int lxc_mainloop_add_handler(struct lxc_epoll_descr *descr, int fd,
  73                              lxc_mainloop_callback_t callback, void *data)
  74 {
  75         struct epoll_event ev;
  76         struct mainloop_handler *handler;
  77         struct lxc_list *item;
  78
  79         handler = malloc(sizeof(*handler));
  80         if (!handler)
  81                 return -1;
  82
  83         handler->callback = callback;
  84         handler->fd = fd;
  85         handler->data = data;
  86
  87         ev.events = EPOLLIN;
  88         ev.data.ptr = handler;
  89
  90         if (epoll_ctl(descr->epfd, EPOLL_CTL_ADD, fd, &ev) < 0)
  91                 goto out_free_handler;
  92
  93         item = malloc(sizeof(*item));
  94         if (!item)
  95                 goto out_free_handler;
  96
  97         item->elem = handler;
  98         lxc_list_add(&descr->handlers, item);
  99         return 0;
 100
 101 out_free_handler:
 102         free(handler);
 103         return -1;
 104 }
 105
 106 int lxc_mainloop_del_handler(struct lxc_epoll_descr *descr, int fd)
 107 {
 108         struct mainloop_handler *handler;
 109         struct lxc_list *iterator;
 110
 111         lxc_list_for_each(iterator, &descr->handlers) {
 112                 handler = iterator->elem;
 113
 114                 if (handler->fd == fd) {
 115                         /* found */
 116                         if (epoll_ctl(descr->epfd, EPOLL_CTL_DEL, fd, NULL))
 117                                 return -1;
 118
 119                         lxc_list_del(iterator);
 120                         free(iterator->elem);
 121                         free(iterator);
 122                         return 0;
 123                 }
 124         }
 125
 126         return -1;
 127 }
 128
 129 int lxc_mainloop_open(struct lxc_epoll_descr *descr)
 130 {
 131         /* hint value passed to epoll create */
 132         descr->epfd = epoll_create(2);
 133         if (descr->epfd < 0)
 134                 return -1;
 135
 136         if (fcntl(descr->epfd, F_SETFD, FD_CLOEXEC)) {
 137                 close(descr->epfd);
 138                 return -1;
 139         }
 140
 141         lxc_list_init(&descr->handlers);
 142         return 0;
 143 }
 144
 145 int lxc_mainloop_close(struct lxc_epoll_descr *descr)
 146 {
 147         struct lxc_list *iterator, *next;
 148
 149         iterator = descr->handlers.next;
 150         while (iterator != &descr->handlers) {
 151                 next = iterator->next;
 152
 153                 lxc_list_del(iterator);
 154                 free(iterator->elem);
 155                 free(iterator);
 156                 iterator = next;
 157         }
 158
 159         return close(descr->epfd);
 160 }
 161