coffcode.h

早期freebsd实现

/* Support for the generic parts of most COFF variants, for BFD.
   Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
   Written by Cygnus Support.

This file is part of BFD, the Binary File Descriptor library.

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 2 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., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* 
Most of this hacked by  Steve Chamberlain,
			[e-mail] 
*/
/*

SECTION
	coff backends

	BFD supports a number of different flavours of coff format.
	The major difference between formats are the sizes and
	alignments of fields in structures on disk, and the occasional
	extra field.  

	Coff in all its varieties is implimented with a few common
	files and a number of implementation specific files. For
	example, The 88k bcs coff format is implemented in the file
	@code{coff-m88k.c}. This file @code{#include}s
	@code{coff-m88k.h} which defines the external structure of the
	coff format for the 88k, and @code{internalcoff.h} which
	defines the internal structure. @code{coff-m88k.c} also
	defines pthe relocations used by the 88k format
	@xref{Relocations}. Then the major portion of coff code is
	included (@code{coffcode.h}) which defines the methods used to
	act upon the types defined in @code{coff-m88k.h} and
	@code{internalcoff.h}.


	The Intel i960 processor version of coff is implemented in
	@code{coff-i960.c}. This file has the same structure as
	@code{coff-m88k.c}, except that it includes @code{coff-i960.h}
	rather than @code{coff-m88k.h}. 

SUBSECTION
	Porting To A New Version of Coff

	The recommended method is to select from the existing
	implimentations the version of coff which is most like the one
	you want to use, for our purposes, we'll say that i386 coff is
	the one you select, and that your coff flavour is called foo.
	Copy the @code{i386coff.c} to @code{foocoff.c}, copy
	@code{../include/i386coff.h} to @code{../include/foocoff.h}
	and add the lines to @code{targets.c} and @code{Makefile.in}
	so that your new back end is used. Alter the shapes of the
	structures in @code{../include/foocoff.h} so that they match
	what you need. You will probably also have to add
	@code{#ifdef}s to the code in @code{internalcoff.h} and
	@code{coffcode.h} if your version of coff is too wild. 

	You can verify that your new BFD backend works quite simply by
	building @code{objdump} from the @code{binutils} directory,
	and making sure that its version of what's going on at your
	host systems idea (assuming it has the pretty standard coff
	dump utility (usually called @code{att-dump} or just
	@code{dump})) are the same.  Then clean up your code, and send
	what you've done to Cygnus. Then your stuff will be in the
	next release, and you won't have to keep integrating it.

SUBSECTION
	How The Coff Backend Works

SUBSUBSECTION
	Bit Twiddling

	Each flavour of coff supported in BFD has its own header file
	descibing the external layout of the structures. There is also
	an internal description of the coff layout (in
	@code{internalcoff.h}) file (@code{}). A major function of the
	coff backend is swapping the bytes and twiddling the bits to
	translate the external form of the structures into the normal
	internal form. This is all performed in the
	@code{bfd_swap}_@i{thing}_@i{direction} routines. Some
	elements are different sizes between different versions of
	coff, it is the duty of the coff version specific include file
	to override the definitions of various packing routines in
	@code{coffcode.h}. Eg the size of line number entry in coff is
	sometimes 16 bits, and sometimes 32 bits. @code{#define}ing
	@code{PUT_LNSZ_LNNO} and @code{GET_LNSZ_LNNO} will select the
	correct one. No doubt, some day someone will find a version of
	coff which has a varying field size not catered for at the
	moment. To port BFD, that person will have to add more @code{#defines}.  
	Three of the bit twiddling routines are exported to
	@code{gdb}; @code{coff_swap_aux_in}, @code{coff_swap_sym_in}
	and @code{coff_swap_linno_in}. @code{GDB} reads the symbol
	table on its own, but uses BFD to fix things up.  More of the
	bit twiddlers are exported for @code{gas};
	@code{coff_swap_aux_out}, @code{coff_swap_sym_out},
	@code{coff_swap_lineno_out}, @code{coff_swap_reloc_out},
	@code{coff_swap_filehdr_out}, @code{coff_swap_aouthdr_out},
	@code{coff_swap_scnhdr_out}. @code{Gas} currently keeps track
	of all the symbol table and reloc drudgery itself, thereby
	saving the internal BFD overhead, but uses BFD to swap things
	on the way out, making cross ports much safer.  This also
	allows BFD (and thus the linker) to use the same header files
	as @code{gas}, which makes one avenue to disaster disappear.

SUBSUBSECTION
	Symbol Reading

	The simple canonical form for symbols used by BFD is not rich
	enough to keep all the information available in a coff symbol
	table. The back end gets around this by keeping the original
	symbol table around, "behind the scenes". 

	When a symbol table is requested (through a call to
	@code{bfd_canonicalize_symtab}, a request gets through to
	@code{get_normalized_symtab}. This reads the symbol table from
	the coff file and swaps all the structures inside into the
	internal form. It also fixes up all the pointers in the table
	(represented in the file by offsets from the first symbol in
	the table) into physical pointers to elements in the new
	internal table. This involves some work since the meanings of
	fields changes depending upon context; a field that is a
	pointer to another structure in the symbol table at one moment
	may be the size in bytes of a structure in the next.  Another
	pass is made over the table. All symbols which mark file names
	(<<C_FILE>> symbols) are modified so that the internal
	string points to the value in the auxent (the real filename)
	rather than the normal text associated with the symbol
	(@code{".file"}). 

	At this time the symbol names are moved around. Coff stores
	all symbols less than nine characters long physically
	within the symbol table, longer strings are kept at the end of
	the file in the string 	table. This pass moves all strings
	into memory, and replaces them with pointers to the strings.


	The symbol table is massaged once again, this time to create
	the canonical table used by the BFD application. Each symbol
	is inspected in turn, and a decision made (using the
	@code{sclass} field) about the various flags to set in the
	@code{asymbol} @xref{Symbols}. The generated canonical table
	shares strings with the hidden internal symbol table. 

	Any linenumbers are read from the coff file too, and attached
	to the symbols which own the functions the linenumbers belong to. 

SUBSUBSECTION
	Symbol Writing

	Writing a symbol to a coff file which didn't come from a coff
	file will lose any debugging information. The @code{asymbol}
	structure remembers the BFD from which was born, and on output
	the back end makes sure that the same destination target as
	source target is present.

	When the symbols have come from a coff file then all the
	debugging information is preserved.

	Symbol tables are provided for writing to the back end in a
	vector of pointers to pointers. This allows applications like
	the linker to accumulate and output large symbol tables
	without having to do too much byte copying.

	This function runs through the provided symbol table and
	patches each symbol marked as a file place holder
	(@code{C_FILE}) to point to the next file place holder in the
	list. It also marks each @code{offset} field in the list with
	the offset from the first symbol of the current symbol.

	Another function of this procedure is to turn the canonical
	value form of BFD into the form used by coff. Internally, BFD
	expects symbol values to be offsets from a section base; so a
	symbol physically at 0x120, but in a section starting at
	0x100, would have the value 0x20. Coff expects symbols to
	contain their final value, so symbols have their values
	changed at this point to reflect their sum with their owning
	section. Note that this transformation uses the
	<<output_section>> field of the @code{asymbol}'s
	@code{asection} @xref{Sections}. 

	o coff_mangle_symbols

	This routine runs though the provided symbol table and uses
	the offsets generated by the previous pass and the pointers
	generated when the symbol table was read in to create the
	structured hierachy required by coff. It changes each pointer
	to a symbol to an index into the symbol table of the symbol
	being referenced. 

	o coff_write_symbols

	This routine runs through the symbol table and patches up the
	symbols from their internal form into the coff way, calls the
	bit twiddlers and writes out the tabel to the file. 

*/

/*
INTERNAL_DEFINITION
	coff_symbol_type

DESCRIPTION
	The hidden information for an asymbol is described in a
	coff_ptr_struct, which is typedefed to a combined_entry_type

CODE_FRAGMENT
.
.typedef struct coff_ptr_struct 
.{
.
.       {* Remembers the offset from the first symbol in the file for
.          this symbol. Generated by coff_renumber_symbols. *}
.unsigned int offset;
.
.       {* Should the tag field of this symbol be renumbered.
.          Created by coff_pointerize_aux. *}
.char fix_tag;
.
.       {* Should the endidx field of this symbol be renumbered.
.          Created by coff_pointerize_aux. *}
.char fix_end;
.
.       {* The container for the symbol structure as read and translated
.           from the file. *}
.
.union {
.   union internal_auxent auxent;
.   struct internal_syment syment;
. } u;
.} combined_entry_type;
.
.
.{* Each canonical asymbol really looks like this: *}
.
.typedef struct coff_symbol_struct
.{
.   {* The actual symbol which the rest of BFD works with *}
.asymbol symbol;
.
.   {* A pointer to the hidden information for this symbol *}
.combined_entry_type *native;
.
.   {* A pointer to the linenumber information for this symbol *}
.struct lineno_cache_entry *lineno;
.
.   {* Have the line numbers been relocated yet ? *}
.boolean done_lineno;
.} coff_symbol_type;


*/

#include "seclet.h"
extern bfd_error_vector_type bfd_error_vector;




#define PUTWORD bfd_h_put_32
#define PUTHALF bfd_h_put_16
#define	PUTBYTE bfd_h_put_8

#ifndef GET_FCN_LNNOPTR
#define GET_FCN_LNNOPTR(abfd, ext)  bfd_h_get_32(abfd, (bfd_byte *) ext->x_sym.x_fcnary.x_fcn.x_lnnoptr)
#endif

#ifndef GET_FCN_ENDNDX
#define GET_FCN_ENDNDX(abfd, ext)  bfd_h_get_32(abfd, (bfd_byte *) ext->x_sym.x_fcnary.x_fcn.x_endndx)
#endif

#ifndef PUT_FCN_LNNOPTR
#define PUT_FCN_LNNOPTR(abfd, in, ext)  PUTWORD(abfd,  in, (bfd_byte *) ext->x_sym.x_fcnary.x_fcn.x_lnnoptr)
#endif
#ifndef PUT_FCN_ENDNDX
#define PUT_FCN_ENDNDX(abfd, in, ext) PUTWORD(abfd, in, (bfd_byte *) ext->x_sym.x_fcnary.x_fcn.x_endndx)
#endif
#ifndef GET_LNSZ_LNNO
#define GET_LNSZ_LNNO(abfd, ext) bfd_h_get_16(abfd, (bfd_byte *) ext->x_sym.x_misc.x_lnsz.x_lnno)
#endif
#ifndef GET_LNSZ_SIZE
#define GET_LNSZ_SIZE(abfd, ext) bfd_h_get_16(abfd, (bfd_byte *) ext->x_sym.x_misc.x_lnsz.x_size)
#endif
#ifndef PUT_LNSZ_LNNO
#define PUT_LNSZ_LNNO(abfd, in, ext) bfd_h_put_16(abfd, in, (bfd_byte *)ext->x_sym.x_misc.x_lnsz.x_lnno)
#endif
#ifndef PUT_LNSZ_SIZE
#define PUT_LNSZ_SIZE(abfd, in, ext) bfd_h_put_16(abfd, in, (bfd_byte*) ext->x_sym.x_misc.x_lnsz.x_size)
#endif
#ifndef GET_SCN_SCNLEN
#define GET_SCN_SCNLEN(abfd,  ext) bfd_h_get_32(abfd, (bfd_byte *) ext->x_scn.x_scnlen)
#endif
#ifndef GET_SCN_NRELOC
#define GET_SCN_NRELOC(abfd,  ext) bfd_h_get_16(abfd, (bfd_byte *)ext->x_scn.x_nreloc)
#endif
#ifndef GET_SCN_NLINNO
#define GET_SCN_NLINNO(abfd, ext)  bfd_h_get_16(abfd, (bfd_byte *)ext->x_scn.x_nlinno)
#endif
#ifndef PUT_SCN_SCNLEN
#define PUT_SCN_SCNLEN(abfd,in, ext) bfd_h_put_32(abfd, in, (bfd_byte *) ext->x_scn.x_scnlen)
#endif
#ifndef PUT_SCN_NRELOC
#define PUT_SCN_NRELOC(abfd,in, ext) bfd_h_put_16(abfd, in, (bfd_byte *)ext->x_scn.x_nreloc)
#endif
#ifndef PUT_SCN_NLINNO
#define PUT_SCN_NLINNO(abfd,in, ext)  bfd_h_put_16(abfd,in, (bfd_byte  *) ext->x_scn.x_nlinno)
#endif
#ifndef GET_LINENO_LNNO
#define GET_LINENO_LNNO(abfd, ext) bfd_h_get_16(abfd, (bfd_byte *) (ext->l_lnno));
#endif
#ifndef PUT_LINENO_LNNO
#define PUT_LINENO_LNNO(abfd,val, ext) bfd_h_put_16(abfd,val,  (bfd_byte *) (ext->l_lnno));
#endif


/* void warning(); */

/*
 * Return a word with STYP_* (scnhdr.s_flags) flags set to represent the
 * incoming SEC_* flags.  The inverse of this function is styp_to_sec_flags().
 * NOTE: If you add to/change this routine, you should mirror the changes
 * 	in styp_to_sec_flags().
 */
static long
DEFUN(sec_to_styp_flags, (sec_name, sec_flags),
	CONST char *		sec_name	AND
	flagword	sec_flags)
{
    long styp_flags = 0;

    if (!strcmp(sec_name, _TEXT)) {
	return((long)STYP_TEXT);
    } else if (!strcmp(sec_name, _DATA)) {
	return((long)STYP_DATA);
    } else if (!strcmp(sec_name, _BSS)) {
	return((long)STYP_BSS);
#ifdef _COMMENT
    } else if (!strcmp(sec_name, _COMMENT)) {
        return((long)STYP_INFO);
#endif /* _COMMENT */
    }

/* Try and figure out what it should be */
   if (sec_flags & SEC_CODE) styp_flags = STYP_TEXT;
   if (sec_flags & SEC_DATA) styp_flags = STYP_DATA;
   else if (sec_flags & SEC_READONLY)
#ifdef STYP_LIT	/* 29k readonly text/data section */
   	styp_flags = STYP_LIT;
#else
   	styp_flags = STYP_TEXT;
#endif	/* STYP_LIT */
   else if (sec_flags & SEC_LOAD) styp_flags = STYP_TEXT;

   if (styp_flags == 0) styp_flags = STYP_BSS;

   return(styp_flags);
}
/*
 * Return a word with SEC_* flags set to represent the incoming
 * STYP_* flags (from scnhdr.s_flags).   The inverse of this
 * function is sec_to_styp_flags().
 * NOTE: If you add to/change this routine, you should mirror the changes
 *      in sec_to_styp_flags().
 */
static flagword
DEFUN(styp_to_sec_flags, (styp_flags),
	long	styp_flags)
{
  flagword	sec_flags=0;

  if ((styp_flags & STYP_TEXT) || (styp_flags & STYP_DATA)) 
  {
    sec_flags = SEC_LOAD | SEC_ALLOC;
  }
  else if (styp_flags & STYP_BSS) 
  {
    sec_flags = SEC_ALLOC;
  }
  else if (styp_flags & STYP_INFO) 
  {
    sec_flags = SEC_NEVER_LOAD;
  }
  else
  {
    sec_flags = SEC_ALLOC | SEC_LOAD;
  }
#ifdef STYP_LIT			/* A29k readonly text/data section type */
  if ((styp_flags & STYP_LIT) == STYP_LIT)
  {
    sec_flags = (SEC_LOAD | SEC_ALLOC | SEC_READONLY);
  }
#endif				/* STYP_LIT */
#ifdef STYP_OTHER_LOAD		/* Other loaded sections */
  if (styp_flags & STYP_OTHER_LOAD)
  {
    sec_flags = (SEC_LOAD | SEC_ALLOC);
  }
#endif				/* STYP_SDATA */

  return(sec_flags);
}

#define	get_index(symbol)	((int) (symbol)->udata)
#define	set_index(symbol, idx)	((symbol)->udata =(PTR) (idx))

/*  **********************************************************************
Here are all the routines for swapping the structures seen in the
outside world into the internal forms.
*/


static void
DEFUN(bfd_swap_reloc_in,(abfd, reloc_src, reloc_dst),
      bfd            *abfd AND
      RELOC *reloc_src AND
      struct internal_reloc *reloc_dst)
{
  reloc_dst->r_vaddr = bfd_h_get_32(abfd, (bfd_byte *)reloc_src->r_vaddr);
  reloc_dst->r_symndx = bfd_h_get_32(abfd, (bfd_byte *) reloc_src->r_symndx);

#ifdef RS6000COFF_C
  reloc_dst->r_type = bfd_h_get_8(abfd, reloc_src->r_type);
  reloc_dst->r_size = bfd_h_get_8(abfd, reloc_src->r_size);
#else
  reloc_dst->r_type = bfd_h_get_16(abfd, (bfd_byte *) reloc_src->r_type);
#endif

#ifdef SWAP_IN_RELOC_OFFSET
  reloc_dst->r_offset = SWAP_IN_RELOC_OFFSET(abfd,
					     (bfd_byte *) reloc_src->r_offset);
#endif