On 16 Nov 2003 at 2:37, David Gillett wrote:

On 14 Nov 2003 at 14:40, Carole Ingraham wrote:

> I hope I'm at the right place. When I run the AVG scan, it says the shell
> 32.DLL site is linked to missing export SHLWAPI.DLL:SHRegGetUSValueA. Does
> anyone know what this is?

  I don't know what "shell 32.DLL site" means, but I'll try to explain a
missing export, and maybe that will be enough to point you in the right
direction.

  Executable code for 32-bit windows may be provided in .EXE files, which
expect to be loaded as a new task/process, and/or in .DLL files which expect
to be loaded into a task already created.  (The "RunDLL.exe" utility
provides a minimal task to load and run code in .DLL files....)

  A .DLL file is a Dynamically-Linked Library.  It's a collection of
functions or subroutines which can be "called" from a task that has loaded
the .DLL.  (The call may come from another .DLL loaded by the same task.
  There are two ways that a DLL can be loaded and called.  In the more
general method, cade uses the system API (Application Programming Interface)
functions to load the DLL, look up a function in the DLL by name, and
transfer execution to it.
  This takes time and effort, often while the user is sitting there,
wondering what's taking so long.  It's also really hard to detect and handle
any errors that may arise.
  There's a simpler and more efficient (and, not surprisingly, therefore
more common) approach, where header information in a .EXE or .DLL file
identifies the DLLs that the program will need, and names the functions
within those DLLs that will be called.  When the OS loads a module (.EXE or
.DLL), it processes this header information, going ahead and loading the
additional DLLs and looking up the function addresses.

  Both approaches involve looking up a function in a DLL by its name.
There's another header piece in each DLL that lists the functions it
provides to programs that use it.  These may not be every function in the
DLL, but these are the ones that it publishes or "exports".

  Okay, so now we can look at the message you see.  Something that AVG is
trying to use, or that it's trying to scan, includes a header which says
that it needs to have the SHLWAPI.DLL file loaded, and that it will be using
a function from that DLL named SHRegGetUSValueA .
  But the SHLWAPI.DLL file that is found on your machine doesn't list
SHRegGetUSValueA as an exported function....

  The most likely cause is that this copy of SHLWAPI.DLL is some earlier
version than your program needs.  Perhaps some recently-installed program
included an old version which it erroniously installed over top of the
correct one.

David Gillett

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