Windows: Be more explicit with Win32 APIs

This addresses several issues in a similar vein:
 - Use the Unicode APIs when possible, running nm on clang shows that we
   only use Unicode APIs except for FormatMessage, CreateSemaphore, and
   GetModuleHandle.  AFAICT, the latter two are coming from MinGW and
   not LLVM itself.
 - Make getMainExecutable more resilient.  It previously considered
   return values of zero from ::GetModuleFileNameA to be acceptable.

llvm-svn: 192096

llvm/lib/Support/Windows/Path.inc

@@ -46,9 +46,9 @@ namespace {
     /*__in*/ LPCWSTR lpTargetFileName,
     /*__in*/ DWORD dwFlags);
 
-  PtrCreateSymbolicLinkW create_symbolic_link_api = PtrCreateSymbolicLinkW(
-    ::GetProcAddress(::GetModuleHandleA("kernel32.dll"),
-                     "CreateSymbolicLinkW"));
+  PtrCreateSymbolicLinkW create_symbolic_link_api =
+      PtrCreateSymbolicLinkW(::GetProcAddress(
+          ::GetModuleHandleW(L"Kernel32.dll"), "CreateSymbolicLinkW"));
 
   error_code TempDir(SmallVectorImpl<wchar_t> &result) {
   retry_temp_dir:
@@ -216,9 +216,28 @@ namespace sys  {
 namespace fs {
 
 std::string getMainExecutable(const char *argv0, void *MainExecAddr) {
-  char pathname[MAX_PATH];
-  DWORD ret = ::GetModuleFileNameA(NULL, pathname, MAX_PATH);
-  return ret != MAX_PATH ? pathname : "";
+  SmallVector<wchar_t, MAX_PATH> PathName;
+  DWORD Size = ::GetModuleFileNameW(NULL, PathName.data(), PathName.capacity());
+
+  // A zero return value indicates a failure other than insufficient space.
+  if (Size == 0)
+    return "";
+
+  // Insufficient space is determined by a return value equal to the size of
+  // the buffer passed in.
+  if (Size == PathName.capacity())
+    return "";
+
+  // On success, GetModuleFileNameW returns the number of characters written to
+  // the buffer not including the NULL terminator.
+  PathName.set_size(Size);
+
+  // Convert the result from UTF-16 to UTF-8.
+  SmallVector<char, MAX_PATH> PathNameUTF8;
+  if (UTF16ToUTF8(PathName.data(), PathName.size(), PathNameUTF8))
+    return "";
+
+  return std::string(PathNameUTF8.data());
 }
 
 UniqueID file_status::getUniqueID() const {
@@ -672,9 +691,8 @@ error_code mapped_file_region::init(int FD, bool CloseFD, uint64_t Offset) {
   case priv:      flprotect = PAGE_WRITECOPY; break;
   }
 
-  FileMappingHandle = ::CreateFileMapping(FileHandle,
-                                          0,
-                                          flprotect,
+  FileMappingHandle =
+      ::CreateFileMappingW(FileHandle, 0, flprotect,
                            (Offset + Size) >> 32,
                            (Offset + Size) & 0xffffffff,
                            0);

llvm/lib/Support/Windows/Program.inc

@@ -335,7 +335,7 @@ static bool Execute(ProcessInfo &PI, StringRef Program, const char **args,
   // Assign the process to a job if a memory limit is defined.
   ScopedJobHandle hJob;
   if (memoryLimit != 0) {
-    hJob = CreateJobObject(0, 0);
+    hJob = CreateJobObjectW(0, 0);
     bool success = false;
     if (hJob) {
       JOBOBJECT_EXTENDED_LIMIT_INFORMATION jeli;

llvm/lib/Support/Windows/RWMutex.inc

@@ -48,7 +48,7 @@ static bool loadSRW() {
   if (!sChecked) {
     sChecked = true;
 
-    HMODULE hLib = ::LoadLibrary(TEXT("Kernel32"));
+    HMODULE hLib = ::LoadLibraryW(L"Kernel32.dll");
     if (hLib) {
       fpInitializeSRWLock =
         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,

llvm/lib/Support/Windows/Signals.inc

@@ -135,7 +135,7 @@ typedef PVOID (WINAPI *fpSymFunctionTableAccess64)(HANDLE, DWORD64);
 static fpSymFunctionTableAccess64 SymFunctionTableAccess64;
 
 static bool load64BitDebugHelp(void) {
-  HMODULE hLib = ::LoadLibrary(TEXT("Dbghelp.dll"));
+  HMODULE hLib = ::LoadLibraryW(L"Dbghelp.dll");
   if (hLib) {
     StackWalk64 = (fpStackWalk64)
                       ::GetProcAddress(hLib, "StackWalk64");