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From: "Ralf Habacker" <Ralf DOT Habacker AT freenet DOT de>
To: "Kde-Cygwin" <kde-cygwin AT kde DOT org>,
   "Binutils" <binutils AT sources DOT redhat DOT com>,
   "Cygwin-Apps" <cygwin-apps AT cygwin DOT com>
Subject: RE: patch for "objdump/cygwin crashes on auto-imported libs" bug
Date: Thu, 25 Apr 2002 19:30:42 +0200
Message-ID: <002701c1ec7e$ecc12580$651c440a@BRAMSCHE>
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> -----Original Message-----
> > From: Ralf Habacker [mailto:Ralf DOT Habacker AT freenet DOT de]
> > Sent: Friday, April 26, 2002 12:09 AM
> >
> > Any comments ?
>
> Looks reasonable to me (on first glances). I'll try and have a closer
> look this weekend if no-one else does.

Perhaps it helps, if I tell some details of this topic. At first the basics are
described in  http://msdn.microsoft.com/msdnmag/issues/02/03/PE2/PE2.asp. See
the chapter "The import sections"

Normally the image_import_descriptor and the Image Adress Table (IAT) identifed
by "first_thunk" are located behind the text segment and idx2 is positive.

On a auto-import image descriptor the main difference is, that the first_thunk
does not point to the import address table (IAT), instead it points to an adress
in the text segment where the opcode reads or write the (auto-imported) data
values. This let idx2 be negative, which I have used for decision.

pe_print_idata (abfd, vfile)
<snip>
  adj = section->vma - extra->ImageBase;
                         0x00400000
<snip>
      hint_addr = bfd_get_32 (abfd, data + i + dataoff);
      time_stamp = bfd_get_32 (abfd, data + i + 4 + dataoff);
      forward_chain = bfd_get_32 (abfd, data + i + 8 + dataoff);
      dll_name = bfd_get_32 (abfd, data + i + 12 + dataoff);
      first_thunk = bfd_get_32 (abfd, data + i + 16 + dataoff);
<snip>

      if (hint_addr != first_thunk && time_stamp == 0)
	{
	  int differ = 0;
	  int idx2;

	  idx2 = first_thunk - adj;

          /* indicates that first_thunk points to an
             data reference in the text segment (auto-import) */
          if (idx2 < 0)
            {
	    fprintf (file,
	     _("\tThe Import Address Table isn't identical (auto-import
descriptor)\n"));
            differ = 1;
	    }
	  else for (j = 0; j < datasize; j += 4)

Regards
Ralf