SHLWAPI 4.71 Ordinal-Only Exports

Version 4.71 introduced 150 distinct functions that are exported by ordinal only. Of these, 119 correspond straightforwardly to standard Windows API functions that work in one way or another with strings. In general, the SHLWAPI equivalents merely wrap the choice of whether to use the standard function in its ANSI or Unicode form, typically depending on whether SHLWAPI finds itself running on Windows or NT. These wrapper functions have the same prototype as the Unicode form of the corresponding standard API function. They can be documented effectively as one simply by describing them in general and then listing which standard API functions have been treated to a Unicode wrapping by SHLWAPI.

That said, no generalised documentation of these Unicode wrappers is provided in the January 2004 edition of the MSDN Library. Specific documentation is given for just seven of them and the choice of which seven is at best capricious. For instance, how does it happen that CharUpperBuffWrapW gets documented but CharLowerBuffWrapW does not—or the other way round, so that CharLowerWrapW gets documented but CharUpperWrapW does not?

By January 2007, for the Windows Vista SDK, Microsoft condescends to the generalised documentation suggested above, yet only for a smattering of eligible functions. Most of the wrappers were anyway trivial by the time that Microsoft got round to documenting them: in version 6.0 starting with the builds for Windows Server 2003, SHLWAPI no longer expects to run on the old Windows that starts from DOS and each of these wrappers is just forwarded to its standard API function.

Of the other ordinal-only exports introduced with SHLWAPI version 4.71, the January 2004 edition of the MSDN Library documents just five. Again, they are all said to require “version 5.0 or later”.

Another four of the ordinal-only exports new to SHLWAPI version 4.71, namely SHAllocShared, SHFreeShared, SHLockShared and SHUnlockShared, have long been re-exported by SHELL32.DLL and have in this sense been documented indirectly as Settlement Program Interfaces. Again however, the documentation misleads about availability, describing them as requiring SHELL32 version 5.0 or higher, as if they did not exist any earlier than 1999. The functions actually date from the NT releases of SHELL32 version 4.0 in 1996. Their redirection to SHLWAPI dates from SHELL32 version 4.71 in 1997. (If only as an aside, note that this shared memory interface is not dead. SHLWAPI version 6.0 in 2001 adds SHLockSharedEx, exported only by ordinal, and left undocumented.)