1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 // TODO(jamiewalch): Add unit tests for this.
7 #include "remoting/host/posix/signal_handler.h"
15 #include "base/compiler_specific.h"
16 #include "base/message_loop/message_loop.h"
17 #include "base/message_loop/message_pump_libevent.h"
18 #include "base/posix/eintr_wrapper.h"
19 #include "base/threading/platform_thread.h"
24 class SignalListener : public base::MessagePumpLibevent::Watcher {
28 void AddSignalHandler(int signal, const SignalHandler& handler);
30 virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
31 virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE {}
33 // WatchFileDescriptor needs a controller through which the operation can be
34 // canceled. We don't use it, but this is as good a place as any to store it.
35 base::MessagePumpLibevent::FileDescriptorWatcher controller;
38 typedef std::pair<int, SignalHandler> SignalAndHandler;
39 typedef std::list<SignalAndHandler> SignalHandlers;
40 SignalHandlers signal_handlers_;
43 SignalListener::SignalListener() {
46 void SignalListener::AddSignalHandler(int signal,
47 const SignalHandler& handler) {
48 signal_handlers_.push_back(SignalAndHandler(signal, handler));
51 void SignalListener::OnFileCanReadWithoutBlocking(int fd) {
53 int result = HANDLE_EINTR(read(fd, &buffer, sizeof(buffer)));
55 for (SignalHandlers::const_iterator i = signal_handlers_.begin();
56 i != signal_handlers_.end();
58 if (i->first == buffer) {
59 i->second.Run(i->first);
65 SignalListener* g_signal_listener = NULL;
68 void GlobalSignalHandler(int signal) {
70 int r ALLOW_UNUSED = write(g_write_fd, &byte, 1);
75 // RegisterSignalHandler registers a signal handler that writes a byte to a
76 // pipe each time a signal is received. The read end of the pipe is registered
77 // with the current MessageLoop (which must be of type IO); whenever the pipe
78 // is readable, it invokes the specified callback.
80 // This arrangement is required because the set of system APIs that are safe to
81 // call from a signal handler is very limited (but does include write).
82 bool RegisterSignalHandler(int signal_number, const SignalHandler& handler) {
83 CHECK(signal_number < 256); // Don't want to worry about multi-byte writes.
84 if (!g_signal_listener) {
85 g_signal_listener = new SignalListener();
89 int result = pipe(pipe_fd);
91 LOG(ERROR) << "Could not create signal pipe: " << errno;
94 base::MessageLoopForIO* message_loop = base::MessageLoopForIO::current();
96 message_loop->WatchFileDescriptor(pipe_fd[0],
98 base::MessageLoopForIO::WATCH_READ,
99 &g_signal_listener->controller,
102 LOG(ERROR) << "Failed to create signal detector task.";
107 g_write_fd = pipe_fd[1];
109 if (signal(signal_number, GlobalSignalHandler) == SIG_ERR) {
110 LOG(ERROR) << "signal() failed: " << errno;
113 g_signal_listener->AddSignalHandler(signal_number, handler);
117 } // namespace remoting