INFO: Windows 2000 Registry Entries Are Not Expanded (237789)

SUMMARY

Before Windows 2000, most in-process applications were placed in the registry with a complete, hard-coded path. In Windows 2000, many of the earlier, absolute, hard-coded paths have been replaced with the appropriate %environment% variable.

MORE INFORMATION

In-process applications are applications that are registered as handlers for a particular file extension (for example, Filename.wri is started by Wordpad, Filename.doc is started by Microsoft Word, and so on).

For instance, in the registry under HKLM/Software/Microsoft/Windows/Current version/App paths, the entry for Wordpad, which was C:\Program Files\Windows NT\Accessories\Wordpad.exe, has become %Program Files%\Windows NT\Accessories\Wordpad.exe.

When an application calls the RegQueryValueEx function to retrieve a string, it should check to see whether lpType==REG_EXPAND_SZ, which means that the application should call the ExpandEnvironmentStrings function, just in case the string returned really does need to be expanded.

These registry values have been REG_EXPAND_SZ for quite some time, but applications expected that these strings were already expanded for them. There are several applications that try to call WinExec with the parameter (%Program Files%\Windows NT\Accessories\Wordpad.exe, and so on) with incorrect results.