118 lines
2.9 KiB
C
118 lines
2.9 KiB
C
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/*
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* Copyright (C) 2013 Intel Corporation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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#include <stdio.h>
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#include <errno.h>
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#include <poll.h>
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#include "pollhandler.h"
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/*
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* Code that allows to poll multiply file descriptors for events
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* File descriptors can be added and removed at runtime
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*
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* Call poll_register_fd function first to add file descriptors to monitor
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* Then call poll_dispatch_loop that will poll all registered file descriptors
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* as long as they are not unregistered.
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*
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* When event happen on given fd appropriate user supplied handler is called
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*/
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/* Maximum number of files to monitor */
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#define MAX_OPEN_FD 10
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/* Storage for pollfd structures for monitored file descriptors */
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static struct pollfd fds[MAX_OPEN_FD];
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static poll_handler fds_handler[MAX_OPEN_FD];
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/* Number of registered file descriptors */
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static int fds_count = 0;
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/*
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* Function polls file descriptor in loop and calls appropriate handler
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* on event. Function returns when there is no more file descriptor to
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* monitor
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*/
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void poll_dispatch_loop(void)
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{
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while (fds_count > 0) {
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int i;
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int cur_fds_count = fds_count;
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int ready = poll(fds, fds_count, 1000);
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for (i = 0; i < fds_count && ready > 0; ++i) {
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if (fds[i].revents == 0)
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continue;
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fds_handler[i](fds + i);
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ready--;
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/*
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* If handler was remove from table
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* just skip the rest and poll again
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* This is due to reordering of tables in
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* register/unregister functions
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*/
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if (cur_fds_count != fds_count)
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break;
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}
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}
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}
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/*
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* Registers file descriptor to be monitored for events (see man poll(2))
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* for events.
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*
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* return non negative value on success
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* -EMFILE when there are to much descriptors
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*/
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int poll_register_fd(int fd, short events, poll_handler ph)
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{
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if (fds_count >= MAX_OPEN_FD)
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return -EMFILE;
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fds_handler[fds_count] = ph;
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fds[fds_count].fd = fd;
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fds[fds_count].events = events;
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fds_count++;
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return fds_count;
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}
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/*
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* Unregisters file descriptor
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* Both fd and ph must match previously registered data
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*
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* return 0 if unregister succeeded
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* -EBADF if arguments do not match any register handler
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*/
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int poll_unregister_fd(int fd, poll_handler ph)
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{
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int i;
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for (i = 0; i < fds_count; ++i) {
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if (fds_handler[i] == ph && fds[i].fd == fd) {
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fds_count--;
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if (i < fds_count) {
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fds[i].fd = fds[fds_count].fd;
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fds[i].events = fds[fds_count].events;
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fds_handler[i] = fds_handler[fds_count];
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}
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return 0;
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}
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}
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return -EBADF;
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}
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