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RE: ordinal linking for cygwin ld
- From: "Robert Collins" <robert dot collins at itdomain dot com dot au>
- To: "Ralf Habacker" <Ralf dot Habacker at freenet dot de>,<kde-cygwin at mail dot kde dot org>,"Charles Wilson" <cwilson at ece dot gatech dot edu>
- Cc: "Binutils" <binutils at sources dot redhat dot com>,"Cygwin-Apps" <cygwin-apps at cygwin dot com>
- Date: Sun, 28 Apr 2002 04:27:07 +1000
- Subject: RE: ordinal linking for cygwin ld
> -----Original Message-----
> From: Ralf Habacker [mailto:Ralf.Habacker@freenet.de]
> Sent: Saturday, April 27, 2002 10:47 PM
> To: firstname.lastname@example.org; Charles Wilson; Robert Collins
> Cc: Binutils; Cygwin-Apps
> Subject: RE: ordinal linking for cygwin ld
> > Well then, this is only half the puzzle. I can see what you
> gain from
> > such a patch, but as Chuck as indicated, it will cause -major-
> > difficulties in management.
> Do you have read the rules I have stated for kde ?
> > We'd probably also need to ensure that strip leaves the
> names in the
> > IAT (I wasn't clear from your other email whether it does that or
> > not).
> Yes it does. See some parts about my auto-import documentation.
> $ objdump -x client.exe
> FirstThunk (2) points to the import address table (IAT),
> which entries are identifed by corresponding _imp_... symbols.
The IAT is an array of IMAGE_THUNK_DATA, that gets overwritten by the
physical PE header of the linked image by the win32 .exe load process.
> HintTab (3) point to a rva (relative virtual address = offset
> from image start) vector pointing to IMAGE_IMPORT_BY_NAME unions.
Huh? The Hinttab->hintname array is an array of IMAGE_THUNK_DATA.
> (4) shows an IMAGE_IMPORT_BY_NAME union for a named link. It
> is identifed by the _nm_<smbol> name . In this structure the
> symbol name string is stored independed from the regular
> symbol name, which can be only stripped.
Hmm. the diagram above is a little misleading. The IMAGE_IMPORT_BY_NAME
struct is not a union. It's IMAGE_THUNK_DATA that is a union, and for
named imports contains that RVA of the IMAGE_IMPORT_BY_NAME struct,
which has both the ordinal and the member name. Lastly there is _no_
requirement for the INT and IAT to share IMAGE_IMPORT_BY_NAME structs,
and they definitely won't share IMAGE_THUNK_DATA elements.
> (5) shows a IMAGE_IMPORT_BY_NAME union for a ordinal link.
Again, this is wrong, it stores a IMAGE_THUNK_DATA union.
> No see this for an auto-imported data
> Hope that helps
Mostly. I'm a bit rusty - it's been a while since I grokked the
auto-import stuff. I'm getting back into it at the moment. The thing
that I don't follow at the moment is the how the linker fixup places the
exported data -variable- at a fixed rva at dll load time. The IAT is
-meant- to point straight to functions after the fixup occurs, so
pointing at an address in the .dll .text segment is fine. I'll re-read
Paul's explanation when I get to looking at your patch anyway.