gdb master recently learnt how to use GetThreadDescription() [1], so set threadnames using SetThreadDescription() [available since Windows 101607] as well.
This is superior to using a special exception to indicate the thread name to the debugger, because the thread name isn't missed if you don't have a debugger attached at the time it's set. It's not clear what the encoding of a thread name string is, we assume UTF8 for the moment. For the moment, continue to use the old method as well, for the benefit of older gdb versions etc. [1] https://sourceware.org/pipermail/gdb-patches/2022-April/187833.html --- winsup/cygwin/autoload.cc | 1 + winsup/cygwin/miscfuncs.cc | 33 +++++++++++++++++++++++++++++++-- 2 files changed, 32 insertions(+), 2 deletions(-) diff --git a/winsup/cygwin/autoload.cc b/winsup/cygwin/autoload.cc index 1f52411d8..cb564d173 100644 --- a/winsup/cygwin/autoload.cc +++ b/winsup/cygwin/autoload.cc @@ -592,6 +592,7 @@ LoadDLLfuncEx (PrefetchVirtualMemory, 16, kernel32, 1) LoadDLLfunc (QueryInterruptTime, 4, KernelBase) LoadDLLfunc (QueryInterruptTimePrecise, 4, KernelBase) LoadDLLfunc (QueryUnbiasedInterruptTimePrecise, 4, KernelBase) +LoadDLLfuncEx (SetThreadDescription, 8, KernelBase, 1) LoadDLLfunc (VirtualAlloc2, 28, KernelBase) LoadDLLfunc (NtMapViewOfSectionEx, 36, ntdll) diff --git a/winsup/cygwin/miscfuncs.cc b/winsup/cygwin/miscfuncs.cc index 739d9de3b..546df929a 100644 --- a/winsup/cygwin/miscfuncs.cc +++ b/winsup/cygwin/miscfuncs.cc @@ -18,6 +18,9 @@ details. */ #include "tls_pbuf.h" #include "mmap_alloc.h" +/* not yet prototyped in w32api */ +extern "C" HRESULT WINAPI SetThreadDescription(HANDLE hThread, PCWSTR lpThreadDescription); + /* Get handle count of an object. */ ULONG get_obj_handle_count (HANDLE h) @@ -993,8 +996,8 @@ wmempcpy: \n\ #define MS_VC_EXCEPTION 0x406D1388 -void -SetThreadName(DWORD dwThreadID, const char* threadName) +static void +SetThreadNameExc(DWORD dwThreadID, const char* threadName) { if (!IsDebuggerPresent ()) return; @@ -1025,6 +1028,32 @@ SetThreadName(DWORD dwThreadID, const char* threadName) __endtry } +void +SetThreadName(DWORD dwThreadID, const char* threadName) +{ + HANDLE hThread = OpenThread (THREAD_SET_LIMITED_INFORMATION, FALSE, dwThreadID); + if (hThread) + { + /* SetThreadDescription only exists in a wide-char version, so we must + convert threadname to wide-char. The encoding of threadName is + unclear, so use UTF8 until we know better. */ + int bufsize = MultiByteToWideChar (CP_UTF8, 0, threadName, -1, NULL, 0); + WCHAR buf[bufsize]; + bufsize = MultiByteToWideChar (CP_UTF8, 0, threadName, -1, buf, bufsize); + HRESULT hr = SetThreadDescription (hThread, buf); + if (hr != S_OK) + { + debug_printf ("SetThreadDescription() failed. %08x %08x\n", + GetLastError (), hr); + } + CloseHandle (hThread); + } + + /* also use the older, exception-based method of setting threadname for the + benefit of things which don't known about GetThreadDescription. */ + SetThreadNameExc(dwThreadID, threadName); +} + #define add_size(p,s) ((p) = ((__typeof__(p))((PBYTE)(p)+(s)))) static WORD num_cpu_per_group = 0; -- 2.36.1