1 //
2 // detail/posix_signal_blocker.hpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9 //
10 
11 #ifndef BOOST_ASIO_DETAIL_POSIX_SIGNAL_BLOCKER_HPP
12 #define BOOST_ASIO_DETAIL_POSIX_SIGNAL_BLOCKER_HPP
13 
14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
15 # pragma once
16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17 
18 #include <boost/asio/detail/config.hpp>
19 
20 #if defined(BOOST_ASIO_HAS_PTHREADS)
21 
22 #include <csignal>
23 #include <pthread.h>
24 #include <signal.h>
25 #include <boost/asio/detail/noncopyable.hpp>
26 
27 #include <boost/asio/detail/push_options.hpp>
28 
29 namespace boost {
30 namespace asio {
31 namespace detail {
32 
33 class posix_signal_blocker
34   : private noncopyable
35 {
36 public:
37   // Constructor blocks all signals for the calling thread.
posix_signal_blocker()38   posix_signal_blocker()
39     : blocked_(false)
40   {
41     sigset_t new_mask;
42     sigfillset(&new_mask);
43     blocked_ = (pthread_sigmask(SIG_BLOCK, &new_mask, &old_mask_) == 0);
44   }
45 
46   // Destructor restores the previous signal mask.
~posix_signal_blocker()47   ~posix_signal_blocker()
48   {
49     if (blocked_)
50       pthread_sigmask(SIG_SETMASK, &old_mask_, 0);
51   }
52 
53   // Block all signals for the calling thread.
block()54   void block()
55   {
56     if (!blocked_)
57     {
58       sigset_t new_mask;
59       sigfillset(&new_mask);
60       blocked_ = (pthread_sigmask(SIG_BLOCK, &new_mask, &old_mask_) == 0);
61     }
62   }
63 
64   // Restore the previous signal mask.
unblock()65   void unblock()
66   {
67     if (blocked_)
68       blocked_ = (pthread_sigmask(SIG_SETMASK, &old_mask_, 0) != 0);
69   }
70 
71 private:
72   // Have signals been blocked.
73   bool blocked_;
74 
75   // The previous signal mask.
76   sigset_t old_mask_;
77 };
78 
79 } // namespace detail
80 } // namespace asio
81 } // namespace boost
82 
83 #include <boost/asio/detail/pop_options.hpp>
84 
85 #endif // defined(BOOST_ASIO_HAS_PTHREADS)
86 
87 #endif // BOOST_ASIO_DETAIL_POSIX_SIGNAL_BLOCKER_HPP
88