win32: pthread: use the new thread naming API

Windows, as of the Creators Update, finally has a sane API for giving a
name to a thread that can be used by debuggers. This is similar to
pthread_setname_np on Linux and some Unixes. Expose it in the pthread
wrapper and use it for mpthread_set_name().

osdep/threads.c

@@ -47,7 +47,7 @@ void mpthread_set_name(const char *name)
         tname[15] = '\0'; // glibc-checked kernel limit
         pthread_setname_np(pthread_self(), tname);
     }
-#elif HAVE_BSD_THREAD_NAME
+#elif HAVE_WIN32_INTERNAL_PTHREADS || HAVE_BSD_THREAD_NAME
     pthread_set_name_np(pthread_self(), tname);
 #elif HAVE_NETBSD_THREAD_NAME
     pthread_setname_np(pthread_self(), "%s", (void *)tname);

osdep/win32/include/pthread.h

@@ -33,6 +33,7 @@
 #define pthread_join m_pthread_join
 #define pthread_detach m_pthread_detach
 #define pthread_create m_pthread_create
+#define pthread_set_name_np m_pthread_set_name_np
 
 #define pthread_once_t INIT_ONCE
 #define PTHREAD_ONCE_INIT INIT_ONCE_STATIC_INIT
@@ -97,4 +98,6 @@ int pthread_detach(pthread_t thread);
 int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
                    void *(*start_routine) (void *), void *arg);
 
+void pthread_set_name_np(pthread_t thread, const char *name);
+
 #endif

osdep/win32/pthread.c

@@ -196,6 +196,29 @@ int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
     return 0;
 }
 
+void pthread_set_name_np(pthread_t thread, const char *name)
+{
+    HMODULE kernel32 = GetModuleHandleW(L"kernel32.dll");
+    if (!kernel32)
+        return;
+    HRESULT (WINAPI *pSetThreadDescription)(HANDLE, PCWSTR) =
+        (void*)GetProcAddress(kernel32, "SetThreadDescription");
+    if (!pSetThreadDescription)
+        return;
+
+    HANDLE th = OpenThread(THREAD_SET_LIMITED_INFORMATION, FALSE, thread.id);
+    if (!th)
+        return;
+    wchar_t wname[80];
+    int wc = MultiByteToWideChar(CP_UTF8, 0, name, -1, wname,
+                                 sizeof(wname) / sizeof(wchar_t) - 1);
+    if (wc > 0) {
+        wname[wc] = L'\0';
+        pSetThreadDescription(th, wname);
+    }
+    CloseHandle(th);
+}
+
 int sem_init(sem_t *sem, int pshared, unsigned int value)
 {
     if (pshared)