Switch out the setup api for using the cabinet API directly....

chrome/installer/mini_installer/decompress.h

+// Copyright (c) 2011 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 CHROME_INSTALLER_MINI_INSTALLER_DECOMPRESS_H_
+#define CHROME_INSTALLER_MINI_INSTALLER_DECOMPRESS_H_
+#pragma once
+
+namespace mini_installer {
+
+// Same as the tool, expand.exe.  Decompresses a file that was compressed
+// using Microsoft's MSCF compression algorithm.
+// The |source| pointer must be writable as internally the name and path
+// of the source file must be temporarily split up and we don't feel like
+// allocating extra buffers for this (in all cases of using this function,
+// the buffers are devoted to this purpose anyway).
+bool Expand(wchar_t* source, const wchar_t* destination);

[amit, 2011/03/15 20:54:35]

if source is writable, why not take in the source size as well?

[tommi (sloooow) - chröme, 2011/03/16 02:43:30]

The idea is similar to how CreateProcess works.  The string must be a valid path
and as such it must be zero terminated.  For sake of simplicity, I chose to have
it writable buffer and avoid creating extra buffers.

[amit, 2011/03/16 15:50:26]

Probably OK but CreateProcess has caused enough pain due to this.
OTOH, if you create a version of WideToUTF8 that takes source length, you won't
need to modify the source arg.

[tommi (sloooow) - chröme, 2011/03/16 20:22:20]

of course (doh)! done!

+
+}  // namespace mini_installer
+
+#endif  // CHROME_INSTALLER_MINI_INSTALLER_DECOMPRESS_H_