//===-- ConnectionGenericFileWindows.cpp ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/Host/windows/ConnectionGenericFileWindows.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Status.h"
#include "lldb/Utility/Timeout.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/ConvertUTF.h"
using namespace lldb;
using namespace lldb_private;
namespace {
// This is a simple helper class to package up the information needed to return
// from a Read/Write operation function. Since there is a lot of code to be
// run before exit regardless of whether the operation succeeded or failed,
// combined with many possible return paths, this is the cleanest way to
// represent it.
class ReturnInfo {
public:
void Set(size_t bytes, ConnectionStatus status, DWORD error_code) {
m_error = Status(error_code, eErrorTypeWin32);
m_bytes = bytes;
m_status = status;
}
void Set(size_t bytes, ConnectionStatus status, llvm::StringRef error_msg) {
m_error = Status::FromErrorString(error_msg.data());
m_bytes = bytes;
m_status = status;
}
size_t GetBytes() const { return m_bytes; }
ConnectionStatus GetStatus() const { return m_status; }
const Status &GetError() const { return m_error; }
private:
Status m_error;
size_t m_bytes;
ConnectionStatus m_status;
};
}
ConnectionGenericFile::ConnectionGenericFile()
: m_file(INVALID_HANDLE_VALUE), m_owns_file(false) {
::ZeroMemory(&m_overlapped, sizeof(m_overlapped));
::ZeroMemory(&m_file_position, sizeof(m_file_position));
InitializeEventHandles();
}
ConnectionGenericFile::ConnectionGenericFile(lldb::file_t file, bool owns_file)
: m_file(file), m_owns_file(owns_file) {
::ZeroMemory(&m_overlapped, sizeof(m_overlapped));
::ZeroMemory(&m_file_position, sizeof(m_file_position));
InitializeEventHandles();
}
ConnectionGenericFile::~ConnectionGenericFile() {
if (m_owns_file && IsConnected())
::CloseHandle(m_file);
::CloseHandle(m_event_handles[kBytesAvailableEvent]);
::CloseHandle(m_event_handles[kInterruptEvent]);
}
void ConnectionGenericFile::InitializeEventHandles() {
m_event_handles[kInterruptEvent] = CreateEvent(NULL, FALSE, FALSE, NULL);
// Note, we should use a manual reset event for the hEvent argument of the
// OVERLAPPED. This is because both WaitForMultipleObjects and
// GetOverlappedResult (if you set the bWait argument to TRUE) will wait for
// the event to be signalled. If we use an auto-reset event,
// WaitForMultipleObjects will reset the event, return successfully, and then
// GetOverlappedResult will block since the event is no longer signalled.
m_event_handles[kBytesAvailableEvent] =
::CreateEvent(NULL, TRUE, FALSE, NULL);
}
bool ConnectionGenericFile::IsConnected() const {
return m_file && (m_file != INVALID_HANDLE_VALUE);
}
lldb::ConnectionStatus ConnectionGenericFile::Connect(llvm::StringRef path,
Status *error_ptr) {
Log *log = GetLog(LLDBLog::Connection);
LLDB_LOGF(log, "%p ConnectionGenericFile::Connect (url = '%s')",
static_cast<void *>(this), path.str().c_str());
if (!path.consume_front("file://")) {
if (error_ptr)
*error_ptr = Status::FromErrorStringWithFormat(
"unsupported connection URL: '%s'", path.str().c_str());
return eConnectionStatusError;
}
if (IsConnected()) {
ConnectionStatus status = Disconnect(error_ptr);
if (status != eConnectionStatusSuccess)
return status;
}
// Open the file for overlapped access. If it does not exist, create it. We
// open it overlapped so that we can issue asynchronous reads and then use
// WaitForMultipleObjects to allow the read to be interrupted by an event
// object.
std::wstring wpath;
if (!llvm::ConvertUTF8toWide(path, wpath)) {
if (error_ptr)
*error_ptr = Status(1, eErrorTypeGeneric);
return eConnectionStatusError;
}
m_file = ::CreateFileW(wpath.c_str(), GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ, NULL, OPEN_ALWAYS,
FILE_FLAG_OVERLAPPED, NULL);
if (m_file == INVALID_HANDLE_VALUE) {
if (error_ptr)
*error_ptr = Status(::GetLastError(), eErrorTypeWin32);
return eConnectionStatusError;
}
m_owns_file = true;
m_uri = path.str();
return eConnectionStatusSuccess;
}
lldb::ConnectionStatus ConnectionGenericFile::Disconnect(Status *error_ptr) {
Log *log = GetLog(LLDBLog::Connection);
LLDB_LOGF(log, "%p ConnectionGenericFile::Disconnect ()",
static_cast<void *>(this));
if (!IsConnected())
return eConnectionStatusSuccess;
// Reset the handle so that after we unblock any pending reads, subsequent
// calls to Read() will see a disconnected state.
HANDLE old_file = m_file;
m_file = INVALID_HANDLE_VALUE;
// Set the disconnect event so that any blocking reads unblock, then cancel
// any pending IO operations.
::CancelIoEx(old_file, &m_overlapped);
// Close the file handle if we owned it, but don't close the event handles.
// We could always reconnect with the same Connection instance.
if (m_owns_file)
::CloseHandle(old_file);
::ZeroMemory(&m_file_position, sizeof(m_file_position));
m_owns_file = false;
m_uri.clear();
return eConnectionStatusSuccess;
}
size_t ConnectionGenericFile::Read(void *dst, size_t dst_len,
const Timeout<std::micro> &timeout,
lldb::ConnectionStatus &status,
Status *error_ptr) {
ReturnInfo return_info;
BOOL result = 0;
DWORD bytes_read = 0;
if (error_ptr)
error_ptr->Clear();
if (!IsConnected()) {
return_info.Set(0, eConnectionStatusNoConnection, ERROR_INVALID_HANDLE);
goto finish;
}
m_overlapped.hEvent = m_event_handles[kBytesAvailableEvent];
result = ::ReadFile(m_file, dst, dst_len, NULL, &m_overlapped);
if (result || ::GetLastError() == ERROR_IO_PENDING) {
if (!result) {
// The expected return path. The operation is pending. Wait for the
// operation to complete or be interrupted.
DWORD milliseconds =
timeout
? std::chrono::duration_cast<std::chrono::milliseconds>(*timeout)
.count()
: INFINITE;
DWORD wait_result = ::WaitForMultipleObjects(
std::size(m_event_handles), m_event_handles, FALSE, milliseconds);
// All of the events are manual reset events, so make sure we reset them
// to non-signalled.
switch (wait_result) {
case WAIT_OBJECT_0 + kBytesAvailableEvent:
break;
case WAIT_OBJECT_0 + kInterruptEvent:
return_info.Set(0, eConnectionStatusInterrupted, 0);
goto finish;
case WAIT_TIMEOUT:
return_info.Set(0, eConnectionStatusTimedOut, 0);
goto finish;
case WAIT_FAILED:
return_info.Set(0, eConnectionStatusError, ::GetLastError());
goto finish;
}
}
// The data is ready. Figure out how much was read and return;
if (!::GetOverlappedResult(m_file, &m_overlapped, &bytes_read, FALSE)) {
DWORD result_error = ::GetLastError();
// ERROR_OPERATION_ABORTED occurs when someone calls Disconnect() during
// a blocking read. This triggers a call to CancelIoEx, which causes the
// operation to complete and the result to be ERROR_OPERATION_ABORTED.
if (result_error == ERROR_HANDLE_EOF ||
result_error == ERROR_OPERATION_ABORTED ||
result_error == ERROR_BROKEN_PIPE)
return_info.Set(bytes_read, eConnectionStatusEndOfFile, 0);
else
return_info.Set(bytes_read, eConnectionStatusError, result_error);
} else if (bytes_read == 0)
return_info.Set(bytes_read, eConnectionStatusEndOfFile, 0);
else
return_info.Set(bytes_read, eConnectionStatusSuccess, 0);
goto finish;
} else if (::GetLastError() == ERROR_BROKEN_PIPE) {
// The write end of a pipe was closed. This is equivalent to EOF.
return_info.Set(0, eConnectionStatusEndOfFile, 0);
} else {
// An unknown error occurred. Fail out.
return_info.Set(0, eConnectionStatusError, ::GetLastError());
}
goto finish;
finish:
status = return_info.GetStatus();
if (error_ptr)
*error_ptr = return_info.GetError();
// kBytesAvailableEvent is a manual reset event. Make sure it gets reset
// here so that any subsequent operations don't immediately see bytes
// available.
ResetEvent(m_event_handles[kBytesAvailableEvent]);
IncrementFilePointer(return_info.GetBytes());
Log *log = GetLog(LLDBLog::Connection);
LLDB_LOGF(log,
"%p ConnectionGenericFile::Read() handle = %p, dst = %p, "
"dst_len = %zu) => %zu, error = %s",
static_cast<void *>(this), m_file, dst, dst_len,
return_info.GetBytes(), return_info.GetError().AsCString());
return return_info.GetBytes();
}
size_t ConnectionGenericFile::Write(const void *src, size_t src_len,
lldb::ConnectionStatus &status,
Status *error_ptr) {
ReturnInfo return_info;
DWORD bytes_written = 0;
BOOL result = 0;
if (error_ptr)
error_ptr->Clear();
if (!IsConnected()) {
return_info.Set(0, eConnectionStatusNoConnection, ERROR_INVALID_HANDLE);
goto finish;
}
m_overlapped.hEvent = NULL;
// Writes are not interruptible like reads are, so just block until it's
// done.
result = ::WriteFile(m_file, src, src_len, NULL, &m_overlapped);
if (!result && ::GetLastError() != ERROR_IO_PENDING) {
return_info.Set(0, eConnectionStatusError, ::GetLastError());
goto finish;
}
if (!::GetOverlappedResult(m_file, &m_overlapped, &bytes_written, TRUE)) {
return_info.Set(bytes_written, eConnectionStatusError, ::GetLastError());
goto finish;
}
return_info.Set(bytes_written, eConnectionStatusSuccess, 0);
goto finish;
finish:
status = return_info.GetStatus();
if (error_ptr)
*error_ptr = return_info.GetError();
IncrementFilePointer(return_info.GetBytes());
Log *log = GetLog(LLDBLog::Connection);
LLDB_LOGF(log,
"%p ConnectionGenericFile::Write() handle = %p, src = %p, "
"src_len = %zu) => %zu, error = %s",
static_cast<void *>(this), m_file, src, src_len,
return_info.GetBytes(), return_info.GetError().AsCString());
return return_info.GetBytes();
}
std::string ConnectionGenericFile::GetURI() { return m_uri; }
bool ConnectionGenericFile::InterruptRead() {
return ::SetEvent(m_event_handles[kInterruptEvent]);
}
void ConnectionGenericFile::IncrementFilePointer(DWORD amount) {
LARGE_INTEGER old_pos;
old_pos.HighPart = m_overlapped.OffsetHigh;
old_pos.LowPart = m_overlapped.Offset;
old_pos.QuadPart += amount;
m_overlapped.Offset = old_pos.LowPart;
m_overlapped.OffsetHigh = old_pos.HighPart;
}
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