labath created this revision. For ptys (at least on Linux), the end-of-file (closing of the slave FD) is signalled by the POLLHUP flag. We were ignoring this flag, which meant that when this happened, we would spin in a loop, continuously calling poll(2) and not making any progress.
This makes sure we treat POLLHUP as a read event (reading will return 0), and we call the registered callback when it happens. This is the behavior our clients expect (and is consistent with how select(2) works). https://reviews.llvm.org/D41008 Files: source/Host/common/MainLoop.cpp unittests/Host/MainLoopTest.cpp Index: unittests/Host/MainLoopTest.cpp =================================================================== --- unittests/Host/MainLoopTest.cpp +++ unittests/Host/MainLoopTest.cpp @@ -8,6 +8,8 @@ //===----------------------------------------------------------------------===// #include "lldb/Host/MainLoop.h" +#include "lldb/Host/ConnectionFileDescriptor.h" +#include "lldb/Host/PseudoTerminal.h" #include "lldb/Host/common/TCPSocket.h" #include "gtest/gtest.h" #include <future> @@ -107,6 +109,24 @@ } #ifdef LLVM_ON_UNIX +TEST_F(MainLoopTest, DetectsEOF) { + lldb_utility::PseudoTerminal term; + ASSERT_TRUE(term.OpenFirstAvailableMaster(O_RDWR, nullptr, 0)); + ASSERT_TRUE(term.OpenSlave(O_RDWR | O_NOCTTY, nullptr, 0)); + auto conn = llvm::make_unique<ConnectionFileDescriptor>( + term.ReleaseMasterFileDescriptor(), true); + + Status error; + MainLoop loop; + auto handle = + loop.RegisterReadObject(conn->GetReadObject(), make_callback(), error); + ASSERT_TRUE(error.Success()); + term.CloseSlaveFileDescriptor(); + + ASSERT_TRUE(loop.Run().Success()); + ASSERT_EQ(1u, callback_count); +} + TEST_F(MainLoopTest, Signal) { MainLoop loop; Status error; Index: source/Host/common/MainLoop.cpp =================================================================== --- source/Host/common/MainLoop.cpp +++ source/Host/common/MainLoop.cpp @@ -221,7 +221,7 @@ for (const auto &handle : fds) { #else for (const auto &fd : read_fds) { - if ((fd.revents & POLLIN) == 0) + if ((fd.revents & (POLLIN | POLLHUP)) == 0) continue; IOObject::WaitableHandle handle = fd.fd; #endif
Index: unittests/Host/MainLoopTest.cpp =================================================================== --- unittests/Host/MainLoopTest.cpp +++ unittests/Host/MainLoopTest.cpp @@ -8,6 +8,8 @@ //===----------------------------------------------------------------------===// #include "lldb/Host/MainLoop.h" +#include "lldb/Host/ConnectionFileDescriptor.h" +#include "lldb/Host/PseudoTerminal.h" #include "lldb/Host/common/TCPSocket.h" #include "gtest/gtest.h" #include <future> @@ -107,6 +109,24 @@ } #ifdef LLVM_ON_UNIX +TEST_F(MainLoopTest, DetectsEOF) { + lldb_utility::PseudoTerminal term; + ASSERT_TRUE(term.OpenFirstAvailableMaster(O_RDWR, nullptr, 0)); + ASSERT_TRUE(term.OpenSlave(O_RDWR | O_NOCTTY, nullptr, 0)); + auto conn = llvm::make_unique<ConnectionFileDescriptor>( + term.ReleaseMasterFileDescriptor(), true); + + Status error; + MainLoop loop; + auto handle = + loop.RegisterReadObject(conn->GetReadObject(), make_callback(), error); + ASSERT_TRUE(error.Success()); + term.CloseSlaveFileDescriptor(); + + ASSERT_TRUE(loop.Run().Success()); + ASSERT_EQ(1u, callback_count); +} + TEST_F(MainLoopTest, Signal) { MainLoop loop; Status error; Index: source/Host/common/MainLoop.cpp =================================================================== --- source/Host/common/MainLoop.cpp +++ source/Host/common/MainLoop.cpp @@ -221,7 +221,7 @@ for (const auto &handle : fds) { #else for (const auto &fd : read_fds) { - if ((fd.revents & POLLIN) == 0) + if ((fd.revents & (POLLIN | POLLHUP)) == 0) continue; IOObject::WaitableHandle handle = fd.fd; #endif
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