coff-go32-exe: support variable-length stubs

The stub size in GO32 executables has historically been fixed at 2048
bytes, due to hardcoded limitations in bfd.  Recent patches to djgpp by
Stas Sergeev (CC'd) have pushed the stub right up to this limit, so if
any further expansion is desired, this must first be patched in bfd.

This series includes three patches:  The first changes the meaning of
the bfd->origin field slightly, so that target code can use this to
specify an offset into the file where the actual bfd is located.
The second patch then uses this to enable support for variable-sized
stubs in the coff-go32-exe format.
The final patch is only a cleanup, it normalizes function and variable
names in coff-stgo32.c so that they all begin with the same prefix.

bfd	* bfdio.c (bfd_bread, bfd_tell, bfd_seek, bfd_mmap): Always add
	bfd->origin to file offset.
	* bfdwin.c (bfd_get_file_window): Likewise.
	* bfd.c: Clarify the use of the bfd->origin field.
	* bfd-in2.h: Regenerate.
	* coff-i386.c: Don't include go32exe.h. Allow overriding
	coff_write_object_contents via COFF_WRITE_CONTENTS.
	* coff-stgo32.c (go32exe_cleanup, go32exe_mkobject)
	(go32exe_write_object_contents): New functions.
	(go32exe_temp_stub, go32exe_temp_stub_size): New static globals.
	(COFF_WRITE_CONTENTS, GO32EXE_DEFAULT_STUB_SIZE): Define.
	(create_go32_stub): Remove check for 2k size limit.  Read stub
	from go32exe_temp_stub if present.
	(go32_stubbed_coff_bfd_copy_private_bfd_data): Allocate and
	copy variable-length stub.
	(go32_check_format): Read stub to go32exe_temp_stub, set
	origin, return go32exe_cleanup.
	(adjust_filehdr_in_post, adjust_filehdr_out_pre)
	(adjust_filehdr_out_post, adjust_scnhdr_in_post)
	(adjust_scnhdr_out_pre, adjust_scnhdr_out_post)
	(adjust_aux_in_post, adjust_aux_out_pre, adjust_aux_out_post):
	Remove functions and their associated #defines.
	* coffcode.h (coff_mkobject_hook): Remove stub copying code.
	* libcoff-in.h: (struct coff_tdata): New field stub_size.
	Rename field go32stub to stub.
	* libcoff.h: Regenerate.
	* coff-stgo32.c (go32_check_format): Rename to...
	(go32exe_check_format): ...this.
	(go32_stubbed_coff_bfd_copy_private_bfd_data): Rename to...
	(go32exe_copy_private_bfd_data): ...this.
	(stub_bytes): Rename to...
	(go32exe_default_stub): ...this.
	(create_go32_stub): Rename to...
	(go32exe_create_stub): ...this.
	* coff-stgo32.c (go32exe_copy_private_bfd_data): Avoid realloc
	when possible.

include	* coff/go32exe.h: Remove file.
	* coff/internal.h (struct internal_filehdr): Remove field
	go32stub.  Remove flag F_GO32STUB.

3 files changed, 7 insertions, 48 deletions

diff --git a/include/ChangeLog b/include/ChangeLog
index 65107bd..7964db2 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-02  Jan W. Jagersma  <jwjagersma@gmail.com>
+
+	* coff/go32exe.h: Remove file.
+	* coff/internal.h (struct internal_filehdr): Remove field
+	go32stub.  Remove flag F_GO32STUB.
+
 2020-04-01  Martin Liska  <mliska@suse.cz>
 	    Maciej W. Rozycki <macro@linux-mips.org>
 
diff --git a/include/coff/go32exe.h b/include/coff/go32exe.h
deleted file mode 100644
index af6de2c..0000000
--- a/include/coff/go32exe.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* COFF information for PC running go32.
-
-   Copyright (C) 2001-2020 Free Software Foundation, Inc.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 3 of the License, or
-   (at your option) any later version.
-   
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-   
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
-   MA 02110-1301, USA.  */
-
-struct external_filehdr_go32_exe
-  {
-    char stub[GO32_STUBSIZE]; /* the stub to load the image */
-			/* the standard COFF header     */
-    char f_magic[2];	/* magic number			*/
-    char f_nscns[2];	/* number of sections		*/
-    char f_timdat[4];	/* time & date stamp		*/
-    char f_symptr[4];	/* file pointer to symtab	*/
-    char f_nsyms[4];	/* number of symtab entries	*/
-    char f_opthdr[2];	/* sizeof(optional hdr)		*/
-    char f_flags[2];	/* flags			*/
-  };
-
-#undef FILHDR
-#define	FILHDR	struct external_filehdr_go32_exe
-#undef FILHSZ
-#define	FILHSZ	GO32_STUBSIZE+20
diff --git a/include/coff/internal.h b/include/coff/internal.h
index 86fe070..2b6c08c 100644
--- a/include/coff/internal.h
+++ b/include/coff/internal.h
@@ -58,19 +58,10 @@ struct internal_extra_pe_filehdr
   bfd_vma  nt_signature;   	/* required NT signature, 0x4550 */
 };
 
-#define GO32_STUBSIZE 2048
-
 struct internal_filehdr
 {
   struct internal_extra_pe_filehdr pe;
 
-  /* coff-stgo32 EXE stub header before BFD tdata has been allocated.
-     Its data is kept in INTERNAL_FILEHDR.GO32STUB afterwards.
-
-     F_GO32STUB is set iff go32stub contains a valid data.  Artifical headers
-     created in BFD have no pre-set go32stub.  */
-  char go32stub[GO32_STUBSIZE];
-
   /* Standard coff internal info.  */
   unsigned short f_magic;	/* magic number			*/
   unsigned int   f_nscns;	/* number of sections		*/
@@ -93,8 +84,7 @@ struct internal_filehdr
  	F_AR32W		file is 32-bit big-endian
  	F_DYNLOAD	rs/6000 aix: dynamically loadable w/imports & exports
  	F_SHROBJ	rs/6000 aix: file is a shared object
-	F_DLL           PE format DLL
-	F_GO32STUB      Field go32stub contains valid data.  */
+	F_DLL           PE format DLL  */
 
 #define	F_RELFLG	(0x0001)
 #define	F_EXEC		(0x0002)
@@ -106,7 +96,6 @@ struct internal_filehdr
 #define	F_DYNLOAD	(0x1000)
 #define	F_SHROBJ	(0x2000)
 #define F_DLL           (0x2000)
-#define F_GO32STUB      (0x4000)
 
 /* Extra structure which is used in the optional header.  */
 typedef struct _IMAGE_DATA_DIRECTORY