Truncation of CPalThread::GetThreadId() return value in InternalCreateThread()

[slowmem]

CPalThread::GetThreadId returns a SIZE_T and the value is used to fill the lpThreadId parameter in InternalCreateThread().

On 64-bit platforms, SIZE_T is 64-bit wide. lpThreadId is an LPDWORD and points to a 32-bit wide variable. This causes a value truncation here: https://github.com/dotnet/coreclr/blob/04d31b78087aadc1399cb52df4c0a4795bfdb23f/src/pal/src/thread/thread.cpp#L737

[kangaroo]

Interestingly, this isn't warned by -Wall or -Wextra, but requires an explicit -Wconversion or -Wshorten-64-to-32. We should add this and do a warning cleanup.

[mikem8361]

Changing the thread id (and process id) to the proper size on *Unix platforms will requires changes from the bottom up starting with the PAL, up into the VM, DBI, DAC and then into the public ICorDebug interfaces. The work required is substantial and the COM interfaces involved will have to be extended in the traditional way (i.e. ICorDebugDataTarget4::GetThreadContext(ULONG64 threadId, ...). The test debugger mdbg will have changed to use the interfaces too.

This is a rough list of the functions that will have to change or be extended:

cordebug.idl/cordebug.h:

HRESULT ICorDebugDataTarget::GetThreadContext(
DWORD dwThreadOSID,
ULONG32 contextFlags,
ULONG32 contextSize,
BYTE * context)

HRESULT ICorDebugMutableDataTarget::SetThreadContext(
/* [in] / DWORD dwThreadID,
/ [in] / ULONG32 contextSize,
/ [size_is][in] */ const BYTE *pContext)

HRESULT ICorDebugVariableSymbol::SetValue(
/* [in] / ULONG32 offset,
/ [in] / DWORD threadID,
/ [in] / ULONG32 cbContext,
/ [size_is][in] / BYTE context[ ],
/ [in] / ULONG32 cbValue,
/ [size_is][in] */ BYTE pValue[ ])

HRESULT ICorDebugController::GetHelperThreadID(DWORD *pThreadID);

HRESULT ICorDebugProcess::SetStopState(DWORD threadID, CorDebugThreadState state);
HRESULT ICorDebugProcess::IsOSSuspended(DWORD threadID, BOOL *pbSuspended);
HRESULT ICorDebugProcess::GetThreadContext(DWORD threadID, ULONG32 contextSize, BYTE context[])
HRESULT ICorDebugProcess::SetThreadContext(DWORD threadID, ULONG32 contextSize, BYTE context[])
HRESULT ICorDebugProcess::ClearCurrentException(DWORD threadID);

corprof.idl/corprof.h:

HRESULT ICorProfilerInfo::GetHandleFromThread(
/* [in] / ThreadID threadId,
/ [out] */ HANDLE *phThread)

HRESULT ICorProfilerInfo::GetThreadInfo(
/* [in] / ThreadID threadId,
/ [out] */ DWORD *pdwWin32ThreadId)

HRESULT ICorProfilerInfo::GetCurrentThreadID(
/* [out] */ ThreadID *pThreadId)

HRESULT ICorProfilerInfo::GetThreadContext(
/* [in] / ThreadID threadId,
/ [out] */ ContextID *pContextId)

dbgeng.h functions implemented by lldb plugin:

HRESULT IDebugSystemObjects::GetCurrentThreadId(
PULONG id);

HRESULT IDebugSystemObjects::SetCurrentThreadId(
ULONG id);

HRESULT IDebugSystemObjects::GetCurrentThreadSystemId(
PULONG sysId);

HRESULT IDebugSystemObjects::GetThreadIdBySystemId(
ULONG sysId,
PULONG threadId);

HRESULT IDebugSystemObjects::GetThreadContextById(
ULONG32 threadID,
ULONG32 contextFlags,
ULONG32 contextSize,
PBYTE context);

VM:

DWORD Thread::GetOSThreadId()
DWORD Thread::GetOSThreadIdForDebugger()

DI:

HRESULT CordbProcess::GetThreadContext(DWORD threadID, ULONG32 contextSize, BYTE context[])
HRESULT CordbProcess::SetThreadContext(DWORD threadID, ULONG32 contextSize, BYTE context[])