1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// TODO(jamiewalch): Add unit tests for this.
#include "remoting/host/posix/signal_handler.h"
#include <errno.h>
#include <signal.h>
#include <list>
#include <memory>
#include <tuple>
#include <utility>
#include "base/compiler_specific.h"
#include "base/files/file_descriptor_watcher_posix.h"
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"
#include "base/threading/platform_thread.h"
namespace remoting {
namespace {
int g_read_fd = 0;
int g_write_fd = 0;
class SignalListener {
public:
SignalListener();
void AddSignalHandler(int signal, const SignalHandler& handler);
void OnFileCanReadWithoutBlocking();
// Throughout the lifetime of this, OnFileCanReadWithoutBlocking() is called
// whenever data is available in |g_read_fd|.
std::unique_ptr<base::FileDescriptorWatcher::Controller> controller;
private:
typedef std::pair<int, SignalHandler> SignalAndHandler;
typedef std::list<SignalAndHandler> SignalHandlers;
SignalHandlers signal_handlers_;
};
SignalListener::SignalListener() = default;
void SignalListener::AddSignalHandler(int signal,
const SignalHandler& handler) {
signal_handlers_.push_back(SignalAndHandler(signal, handler));
}
void SignalListener::OnFileCanReadWithoutBlocking() {
char buffer;
int result = HANDLE_EINTR(read(g_read_fd, &buffer, sizeof(buffer)));
if (result > 0) {
for (SignalHandlers::const_iterator i = signal_handlers_.begin();
i != signal_handlers_.end(); ++i) {
if (i->first == buffer) {
i->second.Run(i->first);
}
}
}
}
SignalListener* g_signal_listener = nullptr;
void GlobalSignalHandler(int signal) {
char byte = signal;
std::ignore = write(g_write_fd, &byte, 1);
}
} // namespace
// RegisterSignalHandler registers a signal handler that writes a byte to a
// pipe each time a signal is received. The read end of the pipe is registered
// with the current MessageLoop (which must be of type IO); whenever the pipe
// is readable, it invokes the specified callback.
//
// This arrangement is required because the set of system APIs that are safe to
// call from a signal handler is very limited (but does include write).
bool RegisterSignalHandler(int signal_number, const SignalHandler& handler) {
CHECK(signal_number < 256); // Don't want to worry about multi-byte writes.
if (!g_signal_listener) {
g_signal_listener = new SignalListener();
}
if (!g_write_fd) {
int pipe_fd[2];
int result = pipe(pipe_fd);
if (result < 0) {
PLOG(ERROR) << "Could not create signal pipe";
return false;
}
g_read_fd = pipe_fd[0];
g_write_fd = pipe_fd[1];
g_signal_listener->controller = base::FileDescriptorWatcher::WatchReadable(
g_read_fd,
base::BindRepeating(&SignalListener::OnFileCanReadWithoutBlocking,
base::Unretained(g_signal_listener)));
}
if (signal(signal_number, GlobalSignalHandler) == SIG_ERR) {
PLOG(ERROR) << "signal() failed";
return false;
}
g_signal_listener->AddSignalHandler(signal_number, handler);
return true;
}
} // namespace remoting
|
