From: "Tim Van Holder" <tim DOT van DOT holder AT pandora DOT be>
To: <djgpp-workers AT delorie DOT com>
Subject: RE: Where does gcc -o foo make foo.exe
Date: Sun, 14 Jan 2001 13:03:08 +0100
Message-ID: <NEBBIOJNGMKPNOBKHCGHMEJCCAAA.tim.van.holder@pandora.be>
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> ??? BFD may be _reading_ the stub, but I'm guessing that it's the 
> application (ld, in this case) which tells it from what file to read it.  
> Otherwise, that would mean that GO32STUB etc. are also pushed to the BFD 
> level, which I don't think is true.
I just checked the current weekly snapshot; only coff-stgo32.c references
$GO32STUB. There's a function create_go32_stub that adds a stub to the
given bfd. It checks $GO32STUB and $STUB for a file to takze the stub from,
otherwise it uses the built-in one. I've included the source of this
function below.

== coff-stgo32.c snippet

static void
create_go32_stub (abfd)
     bfd *abfd;
{
  /* Do it only once */
  if (bfd_coff_go32stub (abfd) == NULL)
    {
      char *stub;
      struct stat st;
      int f;
      unsigned char header[10];
      char magic[8];
      unsigned long coff_start, exe_start;

      /* Check at first the environment variable $(GO32STUB) */
      stub = getenv ("GO32STUB");
      /* Now check the environment variable $(STUB) */
      if (stub == NULL)
	stub = getenv ("STUB");
      if (stub == NULL)
	goto stub_end;
      if (stat (stub, &st) != 0)
	goto stub_end;
#ifdef O_BINARY
      f = open (stub, O_RDONLY | O_BINARY);
#else
      f = open (stub, O_RDONLY);
#endif
      if (f < 0)
	goto stub_end;
      if (read (f, &header, sizeof (header)) < 0)
	{
	  close (f);
	  goto stub_end;
	}
      if (_H (0) != 0x5a4d)	/* it is not an exe file */
	{
	  close (f);
	  goto stub_end;
	}
      /* Compute the size of the stub (it is every thing up
         to the beginning of the coff image) */
      coff_start = (long) _H (2) * 512L;
      if (_H (1))
	coff_start += (long) _H (1) - 512L;

      /* Currently there is only a fixed stub size of 2048 bytes
         supported */
      if (coff_start != 2048)
	{
	  close (f);
	  goto stub_end;
	}
      exe_start = _H (4) * 16;
      if ((unsigned long) lseek (f, exe_start, SEEK_SET) != exe_start)
	{
	  close (f);
	  goto stub_end;
	}
      if (read (f, &magic, 8) != 8)
	{
	  close (f);
	  goto stub_end;
	}
      if (memcmp (magic, "go32stub", 8) != 0)
	{
	  close (f);
	  goto stub_end;
	}
      /* Now we found a correct stub (hopefully) */
      bfd_coff_go32stub (abfd) = (PTR) bfd_alloc (abfd, coff_start);
      if (bfd_coff_go32stub (abfd) == NULL)
	{
	  close (f);
	  return;
	}
      lseek (f, 0L, SEEK_SET);
      if ((unsigned long) read (f, bfd_coff_go32stub (abfd), coff_start)
	  != coff_start)
	{
	  bfd_release (abfd, bfd_coff_go32stub (abfd));
	  bfd_coff_go32stub (abfd) = NULL;
	}
      close (f);
    }
stub_end:
  /* There was something wrong above, so use now the standard builtin
     stub */
  if (bfd_coff_go32stub (abfd) == NULL)
    {
      bfd_coff_go32stub (abfd) = (PTR) bfd_alloc (abfd, STUBSIZE);
      if (bfd_coff_go32stub (abfd) == NULL)
	{
	  return;
	}

      memcpy (bfd_coff_go32stub (abfd), stub_bytes, STUBSIZE);
    }
}

== end of snippet