8ed533acf3
This fixes a freeze bug in the NFS input/storage plugins: when libnfs auto-reconnets after a failure, it installs the new socket on the same file descriptor number. MPD's attempt to unregister the old socket by calling SocketMonitor::Steal() from NfsConnection::ScheduleSocket() fails because the new/old socket number is not registered in epoll, so epoll_ctl() returns ENOENT. The problem is that it left `scheduled_flags`, and so subsequent Schedule() calls will use `EPOLL_CTL_MOD`, which will fail again and again. Instead, we need to use `EPOLL_CTL_ADD` to register the new socket. Closes https://github.com/MusicPlayerDaemon/MPD/issues/806 Closes https://github.com/MusicPlayerDaemon/MPD/issues/756
111 lines
2.5 KiB
C++
111 lines
2.5 KiB
C++
/*
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* Copyright 2003-2018 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "SocketMonitor.hxx"
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#include "Loop.hxx"
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#ifdef USE_EPOLL
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#include <cerrno>
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#endif
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#include <assert.h>
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#ifdef _WIN32
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#include <winsock2.h>
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#else
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#include <sys/socket.h>
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#endif
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void
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SocketMonitor::Dispatch(unsigned flags) noexcept
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{
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flags &= GetScheduledFlags();
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if (flags != 0)
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OnSocketReady(flags);
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}
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SocketMonitor::~SocketMonitor() noexcept
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{
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if (IsDefined())
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Cancel();
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}
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void
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SocketMonitor::Open(SocketDescriptor _fd) noexcept
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{
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assert(!fd.IsDefined());
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assert(_fd.IsDefined());
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fd = _fd;
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}
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SocketDescriptor
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SocketMonitor::Steal() noexcept
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{
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assert(IsDefined());
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Cancel();
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return std::exchange(fd, SocketDescriptor::Undefined());
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}
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void
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SocketMonitor::Close() noexcept
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{
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Steal().Close();
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}
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bool
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SocketMonitor::Schedule(unsigned flags) noexcept
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{
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assert(IsDefined());
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if (flags == GetScheduledFlags())
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return true;
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bool success;
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if (scheduled_flags == 0)
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success = loop.AddFD(fd.Get(), flags, *this);
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else if (flags == 0)
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success = loop.RemoveFD(fd.Get(), *this);
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else
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success = loop.ModifyFD(fd.Get(), flags, *this);
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if (success)
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scheduled_flags = flags;
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#ifdef USE_EPOLL
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else if (errno == EBADF || errno == ENOENT)
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/* the socket was probably closed by somebody else
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(EBADF) or a new file descriptor with the same
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number was created but not registered already
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(ENOENT) - we can assume that there are no
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scheduled events */
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/* note that when this happens, we're actually lucky
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that it has failed - imagine another thread may
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meanwhile have created something on the same file
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descriptor number, and has registered it; the
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epoll_ctl() call above would then have succeeded,
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but broke the other thread's epoll registration */
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scheduled_flags = 0;
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#endif
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return success;
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}
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