[PATCH v2 2/2] coff-go32: support extended relocations

This patch extends the relocation and line number counters for
coff-go32 and coff-go32-exe to 32 bits.  As I understand it works the
same as for PE-COFF:

If the number of relocations in an object file exceeds 65534, the
NRELOC field is set to 65535 and the actual number of relocations is
stored in the VADDR field of the first relocation entry.

Executable files have no relocations, and thus the NRELOC field is
repurposed to extend NLNNO to 32-bits.

bfd	* coff-go32.c (COFF_GO32, IMAGE_SCN_LNK_NRELOC_OVFL)
	(coff_SWAP_scnhdr_in, coff_SWAP_scnhdr_out): Define.
	(_bfd_go32_swap_scnhdr_in, _bfd_go32_swap_scnhdr_out)
	(_bfd_go32_mkobject): New functions.
	* coff-stgo32.c (IMAGE_SCN_LNK_NRELOC_OVFL)
	(coff_SWAP_scnhdr_in, coff_SWAP_scnhdr_out): Define.
	(go32exe_mkobject): Call _bfd_go32_mkobject.
	* coffcode.h (COFF_WITH_EXTENDED_RELOC_COUNTER): Define.
	(coff_set_alignment_hook): Define function for COFF_GO32_EXE
	and COFF_GO32.
	(coff_write_relocs): Enable extended reloc counter code if
	COFF_WITH_EXTENDED_RELOC_COUNTER is defined.  Test for obj_go32.
	(coff_write_object_contents): Likewise.  Pad section headers
	for COFF_GO32 and COFF_GO32EXE.  Use bfd_coff_swap_scnhdr_out
	instead of coff_swap_scnhdr_out.
	* cofflink.c (_bfd_coff_final_link): Test also for obj_go32 to
	enable extended reloc counter.
	* coffswap.h: (coff_swap_scnhdr_in, coff_swap_scnhdr_out):
	Declare with ATTRIBUTE_UNUSED.
	* libcoff-in.h: (struct coff_tdata): New field go32.
	(obj_go32): Define.
	* libcoff.h: Regenerate.

1 files changed, 134 insertions, 0 deletions

diff --git a/bfd/coff-go32.c b/bfd/coff-go32.c
index e43d5ce..4487693 100644
--- a/bfd/coff-go32.c
+++ b/bfd/coff-go32.c
@@ -22,6 +22,7 @@
 #define TARGET_SYM		i386_coff_go32_vec
 #define TARGET_NAME		"coff-go32"
 #define TARGET_UNDERSCORE	'_'
+#define COFF_GO32
 #define COFF_LONG_SECTION_NAMES
 #define COFF_SUPPORT_GNU_LINKONCE
 #define COFF_LONG_FILENAMES
@@ -42,4 +43,137 @@
 { COFF_SECTION_NAME_PARTIAL_MATCH (".gnu.linkonce.wi"), \
   COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }
 
+/* Section contains extended relocations. */
+#define IMAGE_SCN_LNK_NRELOC_OVFL (0x01000000)
+
+#include "sysdep.h"
+#include "bfd.h"
+
+/* The following functions are not static, because they are also
+   used for coff-go32-exe (coff-stgo32.c).  */
+bfd_boolean _bfd_go32_mkobject (bfd *);
+void _bfd_go32_swap_scnhdr_in (bfd *, void *, void *);
+unsigned int _bfd_go32_swap_scnhdr_out (bfd *, void *, void *);
+
+#define coff_mkobject _bfd_go32_mkobject
+#define coff_SWAP_scnhdr_in _bfd_go32_swap_scnhdr_in
+#define coff_SWAP_scnhdr_out _bfd_go32_swap_scnhdr_out
+
 #include "coff-i386.c"
+
+bfd_boolean
+_bfd_go32_mkobject (bfd * abfd)
+{
+  const bfd_size_type amt = sizeof (coff_data_type);
+
+  abfd->tdata.coff_obj_data = bfd_zalloc (abfd, amt);
+  if (abfd->tdata.coff_obj_data == NULL)
+    return FALSE;
+
+  coff_data (abfd)->go32 = TRUE;
+
+  return TRUE;
+}
+
+void
+_bfd_go32_swap_scnhdr_in (bfd * abfd, void * ext, void * in)
+{
+  SCNHDR *scnhdr_ext = (SCNHDR *) ext;
+  struct internal_scnhdr *scnhdr_int = (struct internal_scnhdr *) in;
+
+  memcpy (scnhdr_int->s_name, scnhdr_ext->s_name, sizeof (scnhdr_int->s_name));
+
+  scnhdr_int->s_vaddr = GET_SCNHDR_VADDR (abfd, scnhdr_ext->s_vaddr);
+  scnhdr_int->s_paddr = GET_SCNHDR_PADDR (abfd, scnhdr_ext->s_paddr);
+  scnhdr_int->s_size = GET_SCNHDR_SIZE (abfd, scnhdr_ext->s_size);
+
+  scnhdr_int->s_scnptr = GET_SCNHDR_SCNPTR (abfd, scnhdr_ext->s_scnptr);
+  scnhdr_int->s_relptr = GET_SCNHDR_RELPTR (abfd, scnhdr_ext->s_relptr);
+  scnhdr_int->s_lnnoptr = GET_SCNHDR_LNNOPTR (abfd, scnhdr_ext->s_lnnoptr);
+  scnhdr_int->s_flags = GET_SCNHDR_FLAGS (abfd, scnhdr_ext->s_flags);
+  scnhdr_int->s_nreloc = GET_SCNHDR_NRELOC (abfd, scnhdr_ext->s_nreloc);
+  scnhdr_int->s_nlnno = GET_SCNHDR_NLNNO (abfd, scnhdr_ext->s_nlnno);
+
+  /* DJGPP follows the same strategy as PE COFF.
+     Iff the file is an executable then the higher 16 bits
+     of the line number have been stored in the relocation
+     counter field.  */
+  if (abfd->flags & EXEC_P && (strcmp (scnhdr_ext->s_name, ".text") == 0))
+    {
+      scnhdr_int->s_nlnno
+	= (GET_SCNHDR_NRELOC (abfd, scnhdr_ext->s_nreloc) << 16)
+	  + GET_SCNHDR_NLNNO (abfd, scnhdr_ext->s_nlnno);
+      scnhdr_int->s_nreloc = 0;
+    }
+}
+
+unsigned int
+_bfd_go32_swap_scnhdr_out (bfd * abfd, void * in, void * out)
+{
+  struct internal_scnhdr *scnhdr_int = (struct internal_scnhdr *) in;
+  SCNHDR *scnhdr_ext = (SCNHDR *) out;
+  unsigned int ret = bfd_coff_scnhsz (abfd);
+
+  memcpy (scnhdr_ext->s_name, scnhdr_int->s_name, sizeof (scnhdr_int->s_name));
+
+  PUT_SCNHDR_VADDR (abfd, scnhdr_int->s_vaddr, scnhdr_ext->s_vaddr);
+  PUT_SCNHDR_PADDR (abfd, scnhdr_int->s_paddr, scnhdr_ext->s_paddr);
+  PUT_SCNHDR_SIZE (abfd, scnhdr_int->s_size, scnhdr_ext->s_size);
+  PUT_SCNHDR_SCNPTR (abfd, scnhdr_int->s_scnptr, scnhdr_ext->s_scnptr);
+  PUT_SCNHDR_RELPTR (abfd, scnhdr_int->s_relptr, scnhdr_ext->s_relptr);
+  PUT_SCNHDR_LNNOPTR (abfd, scnhdr_int->s_lnnoptr, scnhdr_ext->s_lnnoptr);
+  PUT_SCNHDR_FLAGS (abfd, scnhdr_int->s_flags, scnhdr_ext->s_flags);
+
+  if (abfd->flags & EXEC_P && (strcmp (scnhdr_int->s_name, ".text") == 0))
+    {
+      /* DJGPP follows the same strategy as PE COFF.
+	 By inference from looking at MS output, the 32 bit field
+	 which is the combination of the number_of_relocs and
+	 number_of_linenos is used for the line number count in
+	 executables.  A 16-bit field won't do for cc1.  The MS
+	 document says that the number of relocs is zero for
+	 executables, but the 17-th bit has been observed to be there.
+	 Overflow is not an issue: a 4G-line program will overflow a
+	 bunch of other fields long before this!  */
+      PUT_SCNHDR_NLNNO (abfd, (scnhdr_int->s_nlnno & 0xffff),
+			scnhdr_ext->s_nlnno);
+      PUT_SCNHDR_NRELOC (abfd, (scnhdr_int->s_nlnno >> 16),
+			 scnhdr_ext->s_nreloc);
+    }
+  else
+    {
+      /* DJGPP follows the same strategy as PE COFF.  */
+      if (scnhdr_int->s_nlnno <= MAX_SCNHDR_NLNNO)
+	PUT_SCNHDR_NLNNO (abfd, scnhdr_int->s_nlnno, scnhdr_ext->s_nlnno);
+      else
+	{
+	  char buf[sizeof (scnhdr_int->s_name) + 1];
+
+	  memcpy (buf, scnhdr_int->s_name, sizeof (scnhdr_int->s_name));
+	  buf[sizeof (scnhdr_int->s_name)] = '\0';
+	  _bfd_error_handler
+	    /* xgettext:c-format */
+	    (_("%pB: warning: %s: line number overflow: 0x%lx > 0xffff"),
+	     abfd, buf, scnhdr_int->s_nlnno);
+	  bfd_set_error (bfd_error_file_truncated);
+	  PUT_SCNHDR_NLNNO (abfd, 0xffff, scnhdr_ext->s_nlnno);
+	  ret = 0;
+	}
+
+      /* Although we could encode 0xffff relocs here, we do not, to be
+	 consistent with other parts of bfd.  Also it lets us warn, as
+	 we should never see 0xffff here w/o having the overflow flag
+	 set.  */
+      if (scnhdr_int->s_nreloc < MAX_SCNHDR_NRELOC)
+	PUT_SCNHDR_NRELOC (abfd, scnhdr_int->s_nreloc, scnhdr_ext->s_nreloc);
+      else
+	{
+	  /* DJGPP can deal with large #s of relocs, but not here.  */
+	  PUT_SCNHDR_NRELOC (abfd, 0xffff, scnhdr_ext->s_nreloc);
+	  scnhdr_int->s_flags |= IMAGE_SCN_LNK_NRELOC_OVFL;
+	  PUT_SCNHDR_FLAGS (abfd, scnhdr_int->s_flags, scnhdr_ext->s_flags);
+	}
+    }
+
+  return ret;
+}