1 files changed, 97 insertions, 0 deletions
diff --git a/base/win/scoped_bstr.h b/base/win/scoped_bstr.h
new file mode 100644
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+++ b/base/win/scoped_bstr.h
@@ -0,0 +1,97 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_WIN_SCOPED_BSTR_H_
+#define BASE_WIN_SCOPED_BSTR_H_
+#pragma once
+
+#include <windows.h>
+#include <oleauto.h>
+
+#include "base/logging.h"
+#include "base/string16.h"
+
+namespace base {
+namespace win {
+
+// Manages a BSTR string pointer.
+// The class interface is based on scoped_ptr.
+class ScopedBstr {
+ public:
+  ScopedBstr() : bstr_(NULL) {
+  }
+
+  // Constructor to create a new BSTR.
+  //
+  // NOTE: Do not pass a BSTR to this constructor expecting ownership to
+  // be transferred - even though it compiles! ;-)
+  explicit ScopedBstr(const char16* non_bstr);
+  ~ScopedBstr();
+
+  // Give ScopedBstr ownership over an already allocated BSTR or NULL.
+  // If you need to allocate a new BSTR instance, use |allocate| instead.
+  void Reset(BSTR bstr = NULL);
+
+  // Releases ownership of the BSTR to the caller.
+  BSTR Release();
+
+  // Creates a new BSTR from a 16-bit C-style string.
+  //
+  // If you already have a BSTR and want to transfer ownership to the
+  // ScopedBstr instance, call |reset| instead.
+  //
+  // Returns a pointer to the new BSTR, or NULL if allocation failed.
+  BSTR Allocate(const char16* str);
+
+  // Allocates a new BSTR with the specified number of bytes.
+  // Returns a pointer to the new BSTR, or NULL if allocation failed.
+  BSTR AllocateBytes(size_t bytes);
+
+  // Sets the allocated length field of the already-allocated BSTR to be
+  // |bytes|.  This is useful when the BSTR was preallocated with e.g.
+  // SysAllocStringLen or SysAllocStringByteLen (call |AllocateBytes|) and then
+  // not all the bytes are being used.
+  //
+  // Note that if you want to set the length to a specific number of
+  // characters, you need to multiply by sizeof(wchar_t).  Oddly, there's no
+  // public API to set the length, so we do this ourselves by hand.
+  //
+  // NOTE: The actual allocated size of the BSTR MUST be >= bytes.  That
+  // responsibility is with the caller.
+  void SetByteLen(size_t bytes);
+
+  // Swap values of two ScopedBstr's.
+  void Swap(ScopedBstr& bstr2);
+
+  // Retrieves the pointer address.
+  // Used to receive BSTRs as out arguments (and take ownership).
+  // The function DCHECKs on the current value being NULL.
+  // Usage: GetBstr(bstr.Receive());
+  BSTR* Receive();
+
+  // Returns number of chars in the BSTR.
+  size_t Length() const;
+
+  // Returns the number of bytes allocated for the BSTR.
+  size_t ByteLength() const;
+
+  operator BSTR() const {
+    return bstr_;
+  }
+
+ protected:
+  BSTR bstr_;
+
+ private:
+  // Forbid comparison of ScopedBstr types.  You should never have the same
+  // BSTR owned by two different scoped_ptrs.
+  bool operator==(const ScopedBstr& bstr2) const;
+  bool operator!=(const ScopedBstr& bstr2) const;
+  DISALLOW_COPY_AND_ASSIGN(ScopedBstr);
+};
+
+}  // namespace win
+}  // namespace base
+
+#endif  // BASE_SCOPED_BSTR_H_