mpd/src/system/EventPipe.cxx
2017-12-16 20:56:06 +01:00

133 lines
3.1 KiB
C++

/*
* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "EventPipe.hxx"
#include "FileDescriptor.hxx"
#include "system/Error.hxx"
#include "util/ScopeExit.hxx"
#include "Compiler.h"
#include <assert.h>
#include <unistd.h>
#ifdef _WIN32
#include "net/IPv4Address.hxx"
#include "net/StaticSocketAddress.hxx"
#include "net/UniqueSocketDescriptor.hxx"
#include "net/SocketError.hxx"
#endif
#ifdef _WIN32
static void PoorSocketPair(int fd[2]);
#endif
EventPipe::EventPipe()
{
#ifdef _WIN32
PoorSocketPair(fds);
#else
FileDescriptor r, w;
if (!FileDescriptor::CreatePipeNonBlock(r, w))
throw MakeErrno("pipe() has failed");
fds[0] = r.Steal();
fds[1] = w.Steal();
#endif
}
EventPipe::~EventPipe()
{
#ifdef _WIN32
closesocket(fds[0]);
closesocket(fds[1]);
#else
close(fds[0]);
close(fds[1]);
#endif
}
bool
EventPipe::Read()
{
assert(fds[0] >= 0);
assert(fds[1] >= 0);
char buffer[256];
#ifdef _WIN32
return recv(fds[0], buffer, sizeof(buffer), 0) > 0;
#else
return read(fds[0], buffer, sizeof(buffer)) > 0;
#endif
}
void
EventPipe::Write()
{
assert(fds[0] >= 0);
assert(fds[1] >= 0);
#ifdef _WIN32
send(fds[1], "", 1, 0);
#else
gcc_unused ssize_t nbytes = write(fds[1], "", 1);
#endif
}
#ifdef _WIN32
/* Our poor man's socketpair() implementation
* Due to limited protocol/address family support
* it's better to keep this as a private implementation detail of EventPipe
* rather than wide-available API.
*/
static void
PoorSocketPair(int fd[2])
{
assert (fd != nullptr);
UniqueSocketDescriptor listen_socket;
if (!listen_socket.CreateNonBlock(AF_INET, SOCK_STREAM, IPPROTO_TCP))
throw MakeSocketError("Failed to create socket");
if (!listen_socket.Bind(IPv4Address(IPv4Address::Loopback(), 0)))
throw MakeSocketError("Failed to create socket");
if (!listen_socket.Listen(1))
throw MakeSocketError("Failed to listen on socket");
UniqueSocketDescriptor socket0;
if (!socket0.Create(AF_INET, SOCK_STREAM, IPPROTO_TCP))
throw MakeSocketError("Failed to create socket");
if (!socket0.Connect(listen_socket.GetLocalAddress()))
throw MakeSocketError("Failed to connect socket");
socket0.SetNonBlocking();
auto socket1 = listen_socket.AcceptNonBlock();
if (!socket1.IsDefined())
throw MakeSocketError("Failed to accept connection");
fd[0] = socket0.Steal();
fd[1] = socket1.Steal();
}
#endif