binutils-gdb/bfd/targets.c

/* Generic target-file-type support for the BFD library.
   Copyright (C) 1990-1991 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.  */

/* $Id$ */

#include <sysdep.h>
#include "bfd.h"
#include "libbfd.h"

/*doc*
@section Targets
Each port of BFD to a different machine requries the creation of a
target back end. All the back end provides to the root part of BFD is
a structure containing pointers to functions which perform certain low
level operations on files. BFD translates the applications's requests
through a pointer into calls to the back end routines.

When a file is opened with @code{bfd_openr}, its format and target are
unknown. BFD uses various mechanisms to determine how to interpret the
file. The operations performed are:
@itemize @bullet
@item
First a BFD is created by calling the internal routine
@code{new_bfd}, then @code{bfd_find_target} is called with the target
string supplied to @code{bfd_openr} and the new BFD pointer. 
@item
If a null target string was provided to
@code{bfd_find_target}, it looks up the environment variable
@code{GNUTARGET} and uses that as the target string. 
@item
If the target string is still NULL, or the target string
is @code{default}, then the first item in the target vector is used as
the target type. @xref{bfd_target}.
@item
Otherwise, the elements in the target vector are
inspected one by one, until a match on target name is found. When
found, that is used.
@item 
Otherwise the error @code{invalid_target} is returned to
@code{bfd_openr}.
@item 
@code{bfd_openr} attempts to open the file using
@code{bfd_open_file}, and returns the BFD.
@end itemize
Once the BFD has been opened and the target selected, the file format
may be determined. This is done by calling @code{bfd_check_format} on
the BFD with a suggested format. The routine returns @code{true} when
the application guesses right.

@menu
* bfd_target::
@end menu
*/


/*proto* bfd_target
@node bfd_target,  , Targets, Targets
@subsection bfd_target
This structure contains everything that BFD knows about a target.
It includes things like its byte order, name, what routines to call
to do various operations, etc.   

Every BFD points to a target structure with its "xvec" member. 


Shortcut for declaring fields which are prototyped function pointers,
while avoiding anguish on compilers that don't support protos.

$#define SDEF(ret, name, arglist) \
$                PROTO(ret,(*name),arglist)
$#define SDEF_FMT(ret, name, arglist) \
$                PROTO(ret,(*name[bfd_type_end]),arglist)

These macros are used to dispatch to functions through the bfd_target
vector. They are used in a number of macros further down in @file{bfd.h}, and
are also used when calling various routines by hand inside the BFD
implementation.  The "arglist" argument must be parenthesized; it
contains all the arguments to the called function.

$#define BFD_SEND(bfd, message, arglist) \
$               ((*((bfd)->xvec->message)) arglist)

For operations which index on the BFD format 

$#define BFD_SEND_FMT(bfd, message, arglist) \
$            (((bfd)->xvec->message[(int)((bfd)->format)]) arglist)

This is the struct which defines the type of BFD this is.  The
"xvec" member of the struct @code{bfd} itself points here.  Each module
that implements access to a different target under BFD, defines
one of these.

FIXME, these names should be rationalised with the names of the
entry points which call them. Too bad we can't have one macro to
define them both! 

*+++

$typedef struct bfd_target
${

identifies the kind of target, eg SunOS4, Ultrix, etc 

$  char *name;

The "flavour" of a back end is a general indication about the contents
of a file.

$  enum target_flavour {
$    bfd_target_unknown_flavour,
$    bfd_target_aout_flavour,
$    bfd_target_coff_flavour,
$    bfd_target_elf_flavour,
$    bfd_target_ieee_flavour,
$    bfd_target_oasys_flavour,
$    bfd_target_srec_flavour} flavour;

The order of bytes within the data area of a file.

$  boolean byteorder_big_p;

The order of bytes within the header parts of a file.

$  boolean header_byteorder_big_p;

This is a mask of all the flags which an executable may have set -
from the set @code{NO_FLAGS}, @code{HAS_RELOC}, ...@code{D_PAGED}.

$  flagword object_flags;       

This is a mask of all the flags which a section may have set - from
the set @code{SEC_NO_FLAGS}, @code{SEC_ALLOC}, ...@code{SET_NEVER_LOAD}.

$  flagword section_flags;

The pad character for filenames within an archive header.

$  char ar_pad_char;            

The maximum number of characters in an archive header.

$ unsigned short ar_max_namelen;

The minimum alignment restriction for any section.

$  unsigned int align_power_min;

Entries for byte swapping for data. These are different to the other
entry points, since they don't take BFD as first arg.  Certain other handlers
could do the same.

$  SDEF (bfd_vma,      bfd_getx64, (bfd_byte *));
$  SDEF (void,         bfd_putx64, (bfd_vma, bfd_byte *));
$  SDEF (bfd_vma, bfd_getx32, (bfd_byte *));
$  SDEF (void,         bfd_putx32, (bfd_vma, bfd_byte *));
$  SDEF (bfd_vma, bfd_getx16, (bfd_byte *));
$  SDEF (void,         bfd_putx16, (bfd_vma, bfd_byte *));

Byte swapping for the headers

$  SDEF (bfd_vma,   bfd_h_getx64, (bfd_byte *));
$  SDEF (void,          bfd_h_putx64, (bfd_vma, bfd_byte *));
$  SDEF (bfd_vma,  bfd_h_getx32, (bfd_byte *));
$  SDEF (void,          bfd_h_putx32, (bfd_vma, bfd_byte *));
$  SDEF (bfd_vma,  bfd_h_getx16, (bfd_byte *));
$  SDEF (void,          bfd_h_putx16, (bfd_vma, bfd_byte *));

Format dependent routines, these turn into vectors of entry points
within the target vector structure; one for each format to check.

Check the format of a file being read.  Return bfd_target * or zero. 

$  SDEF_FMT (struct bfd_target *, _bfd_check_format, (bfd *));

Set the format of a file being written.  

$  SDEF_FMT (boolean,            _bfd_set_format, (bfd *));

Write cached information into a file being written, at bfd_close. 

$  SDEF_FMT (boolean,            _bfd_write_contents, (bfd *));

The following functions are defined in @code{JUMP_TABLE}. The idea is
that the back end writer of @code{foo} names all the routines
@code{foo_}@var{entry_point}, @code{JUMP_TABLE} will built the entries
in this structure in the right order.

Core file entry points

$  SDEF (char *, _core_file_failing_command, (bfd *));
$  SDEF (int,    _core_file_failing_signal, (bfd *));
$  SDEF (boolean, _core_file_matches_executable_p, (bfd *, bfd *));

Archive entry points

$ SDEF (boolean, _bfd_slurp_armap, (bfd *));
$ SDEF (boolean, _bfd_slurp_extended_name_table, (bfd *));
$ SDEF (void,   _bfd_truncate_arname, (bfd *, CONST char *, char *));
$ SDEF (boolean, write_armap, (bfd *arch, 
$                              unsigned int elength,
$                              struct orl *map,
$                              int orl_count, 
$                              int stridx));

Standard stuff.

$  SDEF (boolean, _close_and_cleanup, (bfd *));
$  SDEF (boolean, _bfd_set_section_contents, (bfd *, sec_ptr, PTR,
$                                            file_ptr, bfd_size_type));
$  SDEF (boolean, _bfd_get_section_contents, (bfd *, sec_ptr, PTR, 
$                                            file_ptr, bfd_size_type));
$  SDEF (boolean, _new_section_hook, (bfd *, sec_ptr));

Symbols and reloctions

$ SDEF (unsigned int, _get_symtab_upper_bound, (bfd *));
$  SDEF (unsigned int, _bfd_canonicalize_symtab,
$           (bfd *, struct symbol_cache_entry **));
$  SDEF (unsigned int, _get_reloc_upper_bound, (bfd *, sec_ptr));
$  SDEF (unsigned int, _bfd_canonicalize_reloc, (bfd *, sec_ptr, arelent **,
$                                               struct symbol_cache_entry**));
$  SDEF (struct symbol_cache_entry  *, _bfd_make_empty_symbol, (bfd *));
$  SDEF (void,     _bfd_print_symbol, (bfd *, PTR, struct symbol_cache_entry  *,
$                                      bfd_print_symbol_type));
$#define bfd_print_symbol(b,p,s,e) BFD_SEND(b, _bfd_print_symbol, (b,p,s,e))
$  SDEF (alent *,   _get_lineno, (bfd *, struct symbol_cache_entry  *));
$
$  SDEF (boolean,   _bfd_set_arch_mach, (bfd *, enum bfd_architecture,
$                                       unsigned long));
$
$  SDEF (bfd *,  openr_next_archived_file, (bfd *arch, bfd *prev));
$  SDEF (boolean, _bfd_find_nearest_line,
$        (bfd *abfd, struct sec  *section,
$         struct symbol_cache_entry  **symbols,bfd_vma offset,
$        CONST char **file, CONST char **func, unsigned int *line));
$  SDEF (int,    _bfd_stat_arch_elt, (bfd *, struct stat *));
$
$  SDEF (int,    _bfd_sizeof_headers, (bfd *, boolean));
$
$  SDEF (void, _bfd_debug_info_start, (bfd *));
$  SDEF (void, _bfd_debug_info_end, (bfd *));
$  SDEF (void, _bfd_debug_info_accumulate, (bfd *, struct sec  *));

Special entry points for gdb to swap in coff symbol table parts

$  SDEF(void, _bfd_coff_swap_aux_in,(
$       bfd            *abfd ,
$       PTR             ext,
$       int             type,
$       int             class ,
$       PTR             in));
$
$  SDEF(void, _bfd_coff_swap_sym_in,(
$       bfd            *abfd ,
$       PTR             ext,
$       PTR             in));
$
$  SDEF(void, _bfd_coff_swap_lineno_in,  (
$       bfd            *abfd,
$       PTR            ext,
$       PTR             in));
$
$} bfd_target;

*---

*/
extern bfd_target ecoff_little_vec;
extern bfd_target ecoff_big_vec;
extern bfd_target sunos_big_vec;
extern bfd_target demo_64_vec;
extern bfd_target srec_vec;
extern bfd_target b_out_vec_little_host;
extern bfd_target b_out_vec_big_host;
extern bfd_target icoff_little_vec;
extern bfd_target icoff_big_vec;
extern bfd_target elf_little_vec;
extern bfd_target elf_big_vec;
extern bfd_target ieee_vec;
extern bfd_target oasys_vec;
extern bfd_target m88k_bcs_vec;
extern bfd_target m68kcoff_vec;
extern bfd_target i386coff_vec;
extern bfd_target a29kcoff_big_vec;

#ifdef SELECT_VECS

bfd_target *target_vector[] = {
SELECT_VECS,
0

};
#else
#ifdef DEFAULT_VECTOR
extern bfd_target DEFAULT_VECTOR;
#endif

#ifdef GNU960
#define ICOFF_LITTLE_VEC        icoff_little_vec
#define ICOFF_BIG_VEC           icoff_big_vec
#define B_OUT_VEC_LITTLE_HOST   b_out_vec_little_host
#define B_OUT_VEC_BIG_HOST      b_out_vec_big_host
#endif /* GNU960 */

#ifndef RESTRICTED
#define ECOFF_LITTLE_VEC        ecoff_little_vec
#define ECOFF_BIG_VEC           ecoff_big_vec
#define ICOFF_LITTLE_VEC        icoff_little_vec
#define ICOFF_BIG_VEC           icoff_big_vec
#define ELF_LITTLE_VEC		elf_little_vec
#define ELF_BIG_VEC		elf_big_vec
#define ZB_OUT_VEC_LITTLE_HOST  b_out_vec_little_host
#define ZB_OUT_VEC_BIG_HOST     b_out_vec_big_host
#define SUNOS_VEC_BIG_HOST      sunos_big_vec
#define DEMO_64_VEC             demo_64_vec

/* We have no oasys tools anymore, so we can't test any of this
   anymore. If you want to test the stuff yourself, go ahead...
   steve@cygnus.com */
#if 0
#define OASYS_VEC               oasys_vec
#endif

#define IEEE_VEC                ieee_vec
#define M88K_BCS_VEC            m88k_bcs_vec
#define SREC_VEC                srec_vec
#define M68KCOFF_VEC            m68kcoff_vec
#define I386COFF_VEC            i386coff_vec
#define A29KCOFF_BIG_VEC	a29kcoff_big_vec
#endif

bfd_target *target_vector[] = {

#ifdef DEFAULT_VECTOR
        &DEFAULT_VECTOR,
#endif

#ifdef  I386COFF_VEC
        &I386COFF_VEC,
#endif

#ifdef ECOFF_LITTLE_VEC
        &ECOFF_LITTLE_VEC,
#endif

#ifdef ECOFF_BIG_VEC
        &ECOFF_BIG_VEC,
#endif

#ifdef IEEE_VEC
        &IEEE_VEC,
#endif

#ifdef OASYS_VEC
        &OASYS_VEC,
#endif

#ifdef SUNOS_VEC_BIG_HOST
        &SUNOS_VEC_BIG_HOST,
#endif

#ifdef HOST_64_BIT
#ifdef DEMO_64_VEC
        &DEMO_64_VEC,
#endif
#endif

#ifdef M88K_BCS_VEC
        &M88K_BCS_VEC,
#endif

#ifdef SREC_VEC
        &SREC_VEC,
#endif
        
#ifdef ICOFF_LITTLE_VEC
        &ICOFF_LITTLE_VEC,
#endif

#ifdef ICOFF_BIG_VEC
        &ICOFF_BIG_VEC,
#endif

#ifdef ELF_LITTLE_VEC
        &ELF_LITTLE_VEC,
#endif

#ifdef ELF_BIG_VEC
        &ELF_BIG_VEC,
#endif

#ifdef B_OUT_VEC_LITTLE_HOST
        &B_OUT_VEC_LITTLE_HOST,
#endif

#ifdef B_OUT_VEC_BIG_HOST
        &B_OUT_VEC_BIG_HOST,
#endif

#ifdef  M68KCOFF_VEC
        &M68KCOFF_VEC,
#endif

#ifdef	A29KCOFF_BIG_VEC
	&A29KCOFF_BIG_VEC,
#endif

#ifdef	TRAD_CORE
	&trad_core_big_vec,
	&trad_core_little_vec,
#endif

        NULL, /* end of list marker */
};

#endif

/* default_vector[0] contains either the address of the default vector,
   if there is one, or zero if there isn't.  */

bfd_target *default_vector[] = {
#ifdef DEFAULT_VECTOR
        &DEFAULT_VECTOR,
#endif
        0,
};




/*proto*
*i bfd_find_target
Returns a pointer to the transfer vector for the object target
named target_name.  If target_name is NULL, chooses the one in the
environment variable GNUTARGET; if that is null or not defined then
the first entry in the target list is chosen.  Passing in the
string "default" or setting the environment variable to "default"
will cause the first entry in the target list to be returned,
and "target_defaulted" will be set in the BFD.  This causes
@code{bfd_check_format} to loop over all the targets to find the one
that matches the file being read.  
*; PROTO(bfd_target *, bfd_find_target,(CONST char *, bfd *));
*-*/

bfd_target *
DEFUN(bfd_find_target,(target_name, abfd),
      CONST char *target_name AND
      bfd *abfd)
{
  bfd_target **target;
  extern char *getenv ();
  CONST char *targname = (target_name ? target_name : getenv ("GNUTARGET"));

  /* This is safe; the vector cannot be null */
  if (targname == NULL || !strcmp (targname, "default")) {
    abfd->target_defaulted = true;
    return abfd->xvec = target_vector[0];
  }

  abfd->target_defaulted = false;

  for (target = &target_vector[0]; *target != NULL; target++) {
    if (!strcmp (targname, (*target)->name))
      return abfd->xvec = *target;
  }

  bfd_error = invalid_target;
  return NULL;
}


/*proto*
*i bfd_target_list
This function returns a freshly malloced NULL-terminated vector of the
names of all the valid BFD targets. Do not modify the names 
*; PROTO(CONST char **,bfd_target_list,());

*-*/

CONST char **
DEFUN_VOID(bfd_target_list)
{
  int vec_length= 0;
  bfd_target **target;
  CONST  char **name_list, **name_ptr;

  for (target = &target_vector[0]; *target != NULL; target++)
    vec_length++;

  name_ptr = 
    name_list = (CONST char **) zalloc ((vec_length + 1) * sizeof (char **));

  if (name_list == NULL) {
    bfd_error = no_memory;
    return NULL;
  }

  for (target = &target_vector[0]; *target != NULL; target++)
    *(name_ptr++) = (*target)->name;

  return name_list;
}