Support/Windows: Add ScopedHandle and move some clients over to it.

llvm-svn: 120987

lib/Support/Windows/PathV2.inc

@@ -113,15 +113,14 @@ namespace {
     return success;
   }
 
-  struct AutoCryptoProvider {
-    HCRYPTPROV CryptoProvider;
-
-    ~AutoCryptoProvider() {
-      ::CryptReleaseContext(CryptoProvider, 0);
+  // Forwarder for ScopedHandle.
+  BOOL WINAPI CryptReleaseContext(HCRYPTPROV Provider) {
+    return ::CryptReleaseContext(Provider, 0);
   }
 
-    operator HCRYPTPROV() const {return CryptoProvider;}
-  };
+  typedef ScopedHandle<HCRYPTPROV, HCRYPTPROV(INVALID_HANDLE_VALUE),
+                       BOOL (WINAPI*)(HCRYPTPROV), CryptReleaseContext>
+    ScopedCryptContext;
 }
 
 namespace llvm {
@@ -503,13 +502,14 @@ error_code unique_file(const Twine &model, int &result_fd,
   SmallVector<wchar_t, 128> random_path_utf16;
 
   // Get a Crypto Provider for CryptGenRandom.
-  AutoCryptoProvider CryptoProvider;
-  if (!::CryptAcquireContextW(&CryptoProvider.CryptoProvider,
+  HCRYPTPROV HCPC;
+  if (!::CryptAcquireContextW(&HCPC,
                               NULL,
                               NULL,
                               PROV_RSA_FULL,
                               0))
     return windows_error(::GetLastError());
+  ScopedCryptContext CryptoProvider(HCPC);
 
 retry_random_path:
   random_path_utf16.set_size(0);

lib/Support/Windows/Windows.h

@@ -58,3 +58,43 @@ public:
     return *this;
   }
 };
+
+template <class HandleType, HandleType InvalidHandle,
+          class DeleterType, DeleterType D>
+class ScopedHandle {
+  HandleType Handle;
+
+public:
+  ScopedHandle() : Handle(InvalidHandle) {}
+  ScopedHandle(HandleType handle) : Handle(handle) {}
+
+  ~ScopedHandle() {
+    if (Handle != InvalidHandle)
+      D(Handle);
+  }
+
+  HandleType take() {
+    HandleType temp = Handle;
+    Handle = InvalidHandle;
+    return temp;
+  }
+
+  operator HandleType() const { return Handle; }
+
+  ScopedHandle &operator=(HandleType handle) {
+    Handle = handle;
+    return *this;
+  }
+
+  typedef void (*unspecified_bool_type)();
+  static void unspecified_bool_true() {}
+
+  // True if Handle is valid.
+  operator unspecified_bool_type() const {
+    return Handle == InvalidHandle ? 0 : unspecified_bool_true;
+  }
+
+  typedef ScopedHandle<HANDLE, INVALID_HANDLE_VALUE,
+                       BOOL (WINAPI*)(HANDLE), ::FindClose>
+    ScopedFindHandle;
+};