How to use VerQueryValue? - winapi

Question

I've an exe that will need to retrieve version infomation from a specific dll (ex : FileDescription). My codes already called the GetFileVersionInfoSize and GetFileVersionInfo. But I'm not sure how to apply the VerQueryValue, even after going through http://msdn.microsoft.com/en-us/library/ms647464(v=vs.85) and other examples.
Can someone explain/shed some light on how to apply VerQueryValue and its usage? Thanks.

Answer 1

To get the FileDescription via VerQueryValue, just copy and paste the example code from the VerQueryValue documentation, and modify it as appropriate.
The basic idea behind that example code is:
Use the second form (\VarFileInfo\Translation) to get the list of translations.
Then use the third form (\StringFileInfo\lang-codepage\string-name) to get the string(s).
(The first form () is just for the VS_FIXEDFILEINFO, a set of numerical values for parts of the version number, the flags, etc.)
The example code gets the FileDescription for each language. If you know you only have one language (e.g., because you're looking at your own app, and it isn't translated), you can skip the loop and just return the first one. For more general use, you want to pick the best match for the user's language and return that one.

Answer 2

This is a working example, after many try and errors. I'm using Borland C++, so minor details may need to be changed for incompabible environments.
#include <Windows.h>
std::string GetAppVersion()
{
DWORD dwHandle;
TCHAR fileName[MAX_PATH];
GetModuleFileName(NULL, fileName, MAX_PATH);
DWORD dwSize = GetFileVersionInfoSize(fileName, &dwHandle );
TCHAR buffer[dwSize];
VS_FIXEDFILEINFO* pvFileInfo = NULL;
UINT fiLen = 0;
if ((dwSize > 0) && GetFileVersionInfo(fileName, dwHandle, dwSize, &buffer))
{
VerQueryValue(&buffer, L"\\", (LPVOID*)&pvFileInfo, &fiLen);
}
if (fiLen > 0)
{
char buf[25];
int len = sprintf(buf, "%hu.%hu.%hu.%hu",
HIWORD(pvFileInfo->dwFileVersionMS),
LOWORD(pvFileInfo->dwFileVersionMS),
HIWORD(pvFileInfo->dwFileVersionLS),
LOWORD(pvFileInfo->dwFileVersionLS)
);
return std::string(buf, len);
}
else
{
return std::string("(Unknown)");
}
}