initial custom action library, "hello, world" quality

src/installer-ca/dutil/fileutil.cpp

+//-------------------------------------------------------------------------------------------------
+// <copyright file="fileutil.cpp" company="Outercurve Foundation">
+//   Copyright (c) 2004, Outercurve Foundation.
+//   This software is released under Microsoft Reciprocal License (MS-RL).
+//   The license and further copyright text can be found in the file
+//   LICENSE.TXT at the root directory of the distribution.
+// </copyright>
+//
+// <summary>
+//    File helper functions.
+// </summary>
+//-------------------------------------------------------------------------------------------------
+
+#include "../precomp.h"
+
+/*******************************************************************
+ FileVersion
+
+********************************************************************/
+extern "C" HRESULT DAPI FileVersion(
+    __in LPCWSTR wzFilename,
+    __out DWORD *pdwVerMajor,
+    __out DWORD* pdwVerMinor
+    )
+{
+    HRESULT hr = S_OK;
+
+    DWORD dwHandle = 0;
+    UINT cbVerBuffer = 0;
+    LPVOID pVerBuffer = NULL;
+    VS_FIXEDFILEINFO* pvsFileInfo = NULL;
+    UINT cbFileInfo = 0;
+
+    if (0 == (cbVerBuffer = ::GetFileVersionInfoSizeW(wzFilename, &dwHandle)))
+    {
+        ExitOnLastErrorDebugTrace1(hr, "failed to get version info for file: %ls", wzFilename);
+    }
+
+    pVerBuffer = ::GlobalAlloc(GMEM_FIXED, cbVerBuffer);
+    ExitOnNullDebugTrace1(pVerBuffer, hr, E_OUTOFMEMORY, "failed to allocate version info for file: %ls", wzFilename);
+
+    if (!::GetFileVersionInfoW(wzFilename, dwHandle, cbVerBuffer, pVerBuffer))
+    {
+        ExitOnLastErrorDebugTrace1(hr, "failed to get version info for file: %ls", wzFilename);
+    }
+
+    if (!::VerQueryValueW(pVerBuffer, L"\\", (void**)&pvsFileInfo, &cbFileInfo))
+    {
+        ExitOnLastErrorDebugTrace1(hr, "failed to get version value for file: %ls", wzFilename);
+    }
+
+    *pdwVerMajor = pvsFileInfo->dwFileVersionMS;
+    *pdwVerMinor = pvsFileInfo->dwFileVersionLS;
+
+LExit:
+    if (pVerBuffer)
+    {
+        ::GlobalFree(pVerBuffer);
+    }
+    return hr;
+}