path: root/gnu/usr.bin/binutils/bfd/riscix.c

/* BFD back-end for RISC iX (Acorn, arm) binaries.
   Copyright 1994, 1995, 1996, 1997, 1998, 2000, 2001
   Free Software Foundation, Inc.
   Contributed by Richard Earnshaw (rwe@pegasus.esprit.ec.org)

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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* RISC iX overloads the MAGIC field to indicate more than just the usual
   [ZNO]MAGIC values.  Also included are squeezing information and
   shared library usage.  */

/* The following come from the man page.  */
#define SHLIBLEN 60

#define MF_IMPURE       00200
#define MF_SQUEEZED     01000
#define MF_USES_SL      02000
#define MF_IS_SL        04000

/* Common combinations.  */
#define IMAGIC          (MF_IMPURE|ZMAGIC)      /* Demand load (impure text) */
#define SPOMAGIC        (MF_USES_SL|OMAGIC)     /* OMAGIC with large header */
                                        /* -- may contain a ref to a */
                                        /* shared lib required by the */
                                        /* object.  */
#define SLOMAGIC        (MF_IS_SL|OMAGIC) /* A reference to a shared library */
                                          /* The text portion of the object */
                                          /* contains "overflow text" from */
                                          /* the shared library to be linked */
                                          /* in with an object */
#define QMAGIC          (MF_SQUEEZED|ZMAGIC)    /* Sqeezed demand paged.  */
                                          /* NOTE: This interpretation of */
                                          /* QMAGIC seems to be at variance */
                                          /* With that used on other */
                                          /* architectures.  */
#define SPZMAGIC        (MF_USES_SL|ZMAGIC)     /* program which uses sl */
#define SPQMAGIC        (MF_USES_SL|QMAGIC)     /* sqeezed ditto */
#define SLZMAGIC        (MF_IS_SL|ZMAGIC)       /* shared lib part of prog */
#define SLPZMAGIC       (MF_USES_SL|SLZMAGIC)   /* sl which uses another */

#define N_SHARED_LIB(x) ((x).a_info & MF_USES_SL)

/* Only a pure OMAGIC file has the minimal header */
#define N_TXTOFF(x)                     \
 ((x).a_info == OMAGIC ? 32             \
  : (N_MAGIC(x) == ZMAGIC) ? TARGET_PAGE_SIZE  \
  : 999)

#define N_TXTADDR(x)                                                         \
  (N_MAGIC(x) != ZMAGIC ? 0 /* object file or NMAGIC */                      \
   /* Programs with shared libs are loaded at the first page after all the   \
      text segments of the shared library programs.  Without looking this    \
      up we can't know exactly what the address will be.  A reasonable guess \
      is that a_entry will be in the first page of the executable.  */       \
   : N_SHARED_LIB(x) ? ((x).a_entry & ~(TARGET_PAGE_SIZE - 1))                      \
   : TEXT_START_ADDR)

#define N_SYMOFF(x) \
  (N_TXTOFF (x) + (x).a_text + (x).a_data + (x).a_trsize + (x).a_drsize)

#define N_STROFF(x) (N_SYMOFF (x) + (x).a_syms)

#define TEXT_START_ADDR 32768
#define TARGET_PAGE_SIZE 32768
#define SEGMENT_SIZE TARGET_PAGE_SIZE
#define DEFAULT_ARCH bfd_arch_arm

#define MY(OP) CAT(riscix_,OP)
#define TARGETNAME "a.out-riscix"
#define N_BADMAG(x) ((((x).a_info & ~007200) != ZMAGIC) && \
                     (((x).a_info & ~006000) != OMAGIC) && \
                     ((x).a_info != NMAGIC))
#define N_MAGIC(x) ((x).a_info & ~07200)

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

#define WRITE_HEADERS(abfd, execp)					   \
  {									   \
    bfd_size_type text_size; /* dummy vars */				   \
    file_ptr text_end;							   \
    if (adata(abfd).magic == undecided_magic)				   \
      NAME(aout,adjust_sizes_and_vmas) (abfd, &text_size, &text_end);	   \
    									   \
    execp->a_syms = bfd_get_symcount (abfd) * EXTERNAL_NLIST_SIZE;	   \
    execp->a_entry = bfd_get_start_address (abfd);			   \
    									   \
    execp->a_trsize = ((obj_textsec (abfd)->reloc_count) *		   \
		       obj_reloc_entry_size (abfd));			   \
    execp->a_drsize = ((obj_datasec (abfd)->reloc_count) *		   \
		       obj_reloc_entry_size (abfd));			   \
    NAME(aout,swap_exec_header_out) (abfd, execp, &exec_bytes);		   \
    									   \
    if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) return false;	   \
    if (bfd_write ((PTR) &exec_bytes, 1, EXEC_BYTES_SIZE, abfd)		   \
	!= EXEC_BYTES_SIZE)						   \
      return false;							   \
    /* Now write out reloc info, followed by syms and strings */	   \
									   \
    if (bfd_get_outsymbols (abfd) != (asymbol **) NULL			   \
	&& bfd_get_symcount (abfd) != 0)				   \
      {									   \
	if (bfd_seek (abfd, (file_ptr) (N_SYMOFF(*execp)), SEEK_SET) != 0)  \
	  return false;							   \
									   \
	if (! NAME(aout,write_syms) (abfd)) return false;		   \
									   \
	if (bfd_seek (abfd, (file_ptr) (N_TRELOFF(*execp)), SEEK_SET) != 0) \
	  return false;							   \
									   \
	if (! riscix_squirt_out_relocs (abfd, obj_textsec (abfd)))	   \
	  return false;							   \
	if (bfd_seek (abfd, (file_ptr) (N_DRELOFF(*execp)), SEEK_SET) != 0) \
	  return false;							   \
									   \
	if (!NAME(aout,squirt_out_relocs) (abfd, obj_datasec (abfd)))	   \
	  return false;							   \
      }									   \
  }

#include "libaout.h"
#include "aout/aout64.h"

static bfd_reloc_status_type
riscix_fix_pcrel_26_done PARAMS ((bfd *, arelent *, asymbol *, PTR,
				  asection *, bfd *, char **));

static bfd_reloc_status_type
riscix_fix_pcrel_26 PARAMS ((bfd *, arelent *, asymbol *, PTR,
			     asection *, bfd *, char **));

static reloc_howto_type riscix_std_reloc_howto[] = {
  /* type              rs size bsz  pcrel bitpos ovrf                     sf name     part_inpl readmask  setmask    pcdone */
  HOWTO( 0,              0,  0,   8,  false, 0, complain_overflow_bitfield,0,"8",        true, 0x000000ff,0x000000ff, false),
  HOWTO( 1,              0,  1,   16, false, 0, complain_overflow_bitfield,0,"16",        true, 0x0000ffff,0x0000ffff, false),
  HOWTO( 2,              0,  2,   32, false, 0, complain_overflow_bitfield,0,"32",        true, 0xffffffff,0xffffffff, false),
  HOWTO( 3,              2,  3,   26, true, 0, complain_overflow_signed,  riscix_fix_pcrel_26 , "ARM26",      true, 0x00ffffff,0x00ffffff, false),
  HOWTO( 4,              0,  0,   8,  true,  0, complain_overflow_signed,  0,"DISP8",     true, 0x000000ff,0x000000ff, true),
  HOWTO( 5,              0,  1,   16, true,  0, complain_overflow_signed,  0,"DISP16",    true, 0x0000ffff,0x0000ffff, true),
  HOWTO( 6,              0,  2,   32, true,  0, complain_overflow_signed,  0,"DISP32",    true, 0xffffffff,0xffffffff, true),
  HOWTO( 7,              2,  3,   26, false, 0, complain_overflow_signed,  riscix_fix_pcrel_26_done, "ARM26D",true,0x00ffffff,0x00ffffff, false),
  EMPTY_HOWTO (-1),
  HOWTO( 9,              0, -1,   16, false, 0, complain_overflow_bitfield,0,"NEG16",        true, 0x0000ffff,0x0000ffff, false),
  HOWTO( 10,              0, -2,   32, false, 0, complain_overflow_bitfield,0,"NEG32",        true, 0xffffffff,0xffffffff, false)
};

#define RISCIX_TABLE_SIZE \
  (sizeof (riscix_std_reloc_howto) / sizeof (reloc_howto_type))

static bfd_reloc_status_type
riscix_fix_pcrel_26_done (abfd, reloc_entry, symbol, data, input_section,
			  output_bfd, error_message)
     bfd *abfd ATTRIBUTE_UNUSED;
     arelent *reloc_entry ATTRIBUTE_UNUSED;
     asymbol *symbol ATTRIBUTE_UNUSED;
     PTR data ATTRIBUTE_UNUSED;
     asection *input_section ATTRIBUTE_UNUSED;
     bfd *output_bfd ATTRIBUTE_UNUSED;
     char **error_message ATTRIBUTE_UNUSED;
{
  /* This is dead simple at present.  */
  return bfd_reloc_ok;
}

static bfd_reloc_status_type
riscix_fix_pcrel_26 (abfd, reloc_entry, symbol, data, input_section,
		     output_bfd, error_message)
     bfd *abfd;
     arelent *reloc_entry;
     asymbol *symbol;
     PTR data;
     asection *input_section;
     bfd *output_bfd;
     char **error_message ATTRIBUTE_UNUSED;
{
  bfd_vma relocation;
  bfd_size_type addr = reloc_entry->address;
  long target = bfd_get_32 (abfd, (bfd_byte *) data + addr);
  bfd_reloc_status_type flag = bfd_reloc_ok;

  /* If this is an undefined symbol, return error */
  if (symbol->section == &bfd_und_section
      && (symbol->flags & BSF_WEAK) == 0)
    return output_bfd ? bfd_reloc_continue : bfd_reloc_undefined;

  /* If the sections are different, and we are doing a partial relocation,
     just ignore it for now.  */
  if (symbol->section->name != input_section->name
      && output_bfd != (bfd *)NULL)
    return bfd_reloc_continue;

  relocation = (target & 0x00ffffff) << 2;
  relocation = (relocation ^ 0x02000000) - 0x02000000; /* Sign extend */
  relocation += symbol->value;
  relocation += symbol->section->output_section->vma;
  relocation += symbol->section->output_offset;
  relocation += reloc_entry->addend;
  relocation -= input_section->output_section->vma;
  relocation -= input_section->output_offset;
  relocation -= addr;
  if (relocation & 3)
    return bfd_reloc_overflow;

  /* Check for overflow */
  if (relocation & 0x02000000)
    {
      if ((relocation & ~ (bfd_vma) 0x03ffffff) != ~ (bfd_vma) 0x03ffffff)
	flag = bfd_reloc_overflow;
    }
  else if (relocation & ~0x03ffffff)
    flag = bfd_reloc_overflow;

  target &= ~0x00ffffff;
  target |= (relocation >> 2) & 0x00ffffff;
  bfd_put_32 (abfd, target, (bfd_byte *) data + addr);

  /* Now the ARM magic... Change the reloc type so that it is marked as done.
     Strictly this is only necessary if we are doing a partial relocation.  */
  reloc_entry->howto = &riscix_std_reloc_howto[7];

  return flag;
}

reloc_howto_type *
riscix_reloc_type_lookup (abfd, code)
     bfd *abfd;
     bfd_reloc_code_real_type code;
{
#define ASTD(i,j)       case i: return &riscix_std_reloc_howto[j]
  if (code == BFD_RELOC_CTOR)
    switch (bfd_get_arch_info (abfd)->bits_per_address)
      {
      case 32:
        code = BFD_RELOC_32;
        break;
      default: return (reloc_howto_type *) NULL;
      }

  switch (code)
    {
      ASTD (BFD_RELOC_16, 1);
      ASTD (BFD_RELOC_32, 2);
      ASTD (BFD_RELOC_ARM_PCREL_BRANCH, 3);
      ASTD (BFD_RELOC_8_PCREL, 4);
      ASTD (BFD_RELOC_16_PCREL, 5);
      ASTD (BFD_RELOC_32_PCREL, 6);
    default: return (reloc_howto_type *) NULL;
    }
}

#define MY_bfd_link_hash_table_create _bfd_generic_link_hash_table_create
#define MY_bfd_link_add_symbols _bfd_generic_link_add_symbols
#define MY_final_link_callback should_not_be_used
#define MY_bfd_final_link _bfd_generic_final_link

#define MY_bfd_reloc_type_lookup riscix_reloc_type_lookup
#define MY_canonicalize_reloc riscix_canonicalize_reloc
#define MY_object_p riscix_object_p

static const bfd_target *riscix_callback PARAMS ((bfd *));

void
riscix_swap_std_reloc_out (abfd, g, natptr)
     bfd *abfd;
     arelent *g;
     struct reloc_std_external *natptr;
{
  int r_index;
  asymbol *sym = *(g->sym_ptr_ptr);
  int r_extern;
  int r_length;
  int r_pcrel;
  int r_neg = 0;	/* Negative relocs use the BASEREL bit.  */
  asection *output_section = sym->section->output_section;

  PUT_WORD(abfd, g->address, natptr->r_address);

  r_length = g->howto->size ;   /* Size as a power of two */
  if (r_length < 0)
    {
      r_length = -r_length;
      r_neg = 1;
    }

  r_pcrel  = (int) g->howto->pc_relative; /* Relative to PC? */

  /* For RISC iX, in pc-relative relocs the r_pcrel bit means that the
     relocation has been done already (Only for the 26-bit one I think)???!!!
     */

  if (r_length == 3)
    r_pcrel = r_pcrel ? 0 : 1;

#if 0
  /* For a standard reloc, the addend is in the object file.  */
  r_addend = g->addend + (*(g->sym_ptr_ptr))->section->output_section->vma;
#endif

  /* name was clobbered by aout_write_syms to be symbol index */

  /* If this relocation is relative to a symbol then set the
     r_index to the symbols index, and the r_extern bit.

     Absolute symbols can come in in two ways, either as an offset
     from the abs section, or as a symbol which has an abs value.
     check for that here
     */

  if (bfd_is_com_section (output_section)
      || output_section == &bfd_abs_section
      || output_section == &bfd_und_section)
    {
      if (bfd_abs_section.symbol == sym)
	{
	  /* Whoops, looked like an abs symbol, but is really an offset
	     from the abs section */
	  r_index = 0;
	  r_extern = 0;
	}
      else
	{
	  /* Fill in symbol */
	  r_extern = 1;
	  r_index = (*g->sym_ptr_ptr)->udata.i;
	}
    }
  else
    {
      /* Just an ordinary section */
      r_extern = 0;
      r_index  = output_section->target_index;
    }

  /* now the fun stuff */
  if (bfd_header_big_endian (abfd))
    {
      natptr->r_index[0] = r_index >> 16;
      natptr->r_index[1] = r_index >> 8;
      natptr->r_index[2] = r_index;
      natptr->r_type[0] =
	(  (r_extern ?   RELOC_STD_BITS_EXTERN_BIG: 0)
	 | (r_pcrel  ?   RELOC_STD_BITS_PCREL_BIG: 0)
	 | (r_neg    ?   RELOC_STD_BITS_BASEREL_BIG: 0)
	 | (r_length <<  RELOC_STD_BITS_LENGTH_SH_BIG));
    }
  else
    {
      natptr->r_index[2] = r_index >> 16;
      natptr->r_index[1] = r_index >> 8;
      natptr->r_index[0] = r_index;
      natptr->r_type[0] =
	(  (r_extern ?   RELOC_STD_BITS_EXTERN_LITTLE: 0)
	 | (r_pcrel  ?   RELOC_STD_BITS_PCREL_LITTLE: 0)
	 | (r_neg    ?   RELOC_STD_BITS_BASEREL_LITTLE: 0)
	 | (r_length <<  RELOC_STD_BITS_LENGTH_SH_LITTLE));
    }
}

boolean
riscix_squirt_out_relocs (abfd, section)
     bfd *abfd;
     asection *section;
{
  arelent **generic;
  unsigned char *native, *natptr;
  size_t each_size;

  unsigned int count = section->reloc_count;
  size_t natsize;

  if (count == 0) return true;

  each_size = obj_reloc_entry_size (abfd);
  natsize = each_size * count;
  native = (unsigned char *) bfd_zalloc (abfd, natsize);
  if (!native)
    return false;

  generic = section->orelocation;

  for (natptr = native;
       count != 0;
       --count, natptr += each_size, ++generic)
    riscix_swap_std_reloc_out (abfd, *generic,
			       (struct reloc_std_external *) natptr);

  if ( bfd_write ((PTR) native, 1, natsize, abfd) != natsize)
    {
      bfd_release(abfd, native);
      return false;
    }

  bfd_release (abfd, native);
  return true;
}

/*
 * This is just like the standard aoutx.h version but we need to do our
 * own mapping of external reloc type values to howto entries.
 */
long
MY(canonicalize_reloc) (abfd, section, relptr, symbols)
      bfd *abfd;
      sec_ptr section;
      arelent **relptr;
      asymbol **symbols;
{
  arelent *tblptr = section->relocation;
  unsigned int count, c;
  extern reloc_howto_type NAME(aout,std_howto_table)[];

  /* If we have already read in the relocation table, return the values.  */
  if (section->flags & SEC_CONSTRUCTOR) {
    arelent_chain *chain = section->constructor_chain;

    for (count = 0; count < section->reloc_count; count++) {
      *relptr++ = &chain->relent;
      chain = chain->next;
    }
    *relptr = 0;
    return section->reloc_count;
  }
  if (tblptr && section->reloc_count) {
    for (count = 0; count++ < section->reloc_count;)
      *relptr++ = tblptr++;
    *relptr = 0;
    return section->reloc_count;
  }

  if (!NAME(aout,slurp_reloc_table) (abfd, section, symbols))
    return -1;
  tblptr = section->relocation;

  /* fix up howto entries */
  for (count = 0; count++ < section->reloc_count;)
    {
      c = tblptr->howto - NAME(aout,std_howto_table);
      BFD_ASSERT (c < RISCIX_TABLE_SIZE);
      tblptr->howto = &riscix_std_reloc_howto[c];

      *relptr++ = tblptr++;
    }
  *relptr = 0;
  return section->reloc_count;
}

/* This is the same as NAME(aout,some_aout_object_p), but has different
   expansions of the macro definitions.  */

const bfd_target *
riscix_some_aout_object_p (abfd, execp, callback_to_real_object_p)
     bfd *abfd;
     struct internal_exec *execp;
     const bfd_target *(*callback_to_real_object_p) PARAMS ((bfd *));
{
  struct aout_data_struct *rawptr, *oldrawptr;
  const bfd_target *result;

  rawptr = ((struct aout_data_struct  *)
	    bfd_zalloc (abfd, sizeof (struct aout_data_struct )));

  if (rawptr == NULL)
    return 0;

  oldrawptr = abfd->tdata.aout_data;
  abfd->tdata.aout_data = rawptr;

  /* Copy the contents of the old tdata struct.
     In particular, we want the subformat, since for hpux it was set in
     hp300hpux.c:swap_exec_header_in and will be used in
     hp300hpux.c:callback.  */
  if (oldrawptr != NULL)
    *abfd->tdata.aout_data = *oldrawptr;

  abfd->tdata.aout_data->a.hdr = &rawptr->e;
  *(abfd->tdata.aout_data->a.hdr) = *execp;     /* Copy in the internal_exec
						   struct */
  execp = abfd->tdata.aout_data->a.hdr;

  /* Set the file flags */
  abfd->flags = BFD_NO_FLAGS;
  if (execp->a_drsize || execp->a_trsize)
    abfd->flags |= HAS_RELOC;
  /* Setting of EXEC_P has been deferred to the bottom of this function */
  if (execp->a_syms)
    abfd->flags |= HAS_LINENO | HAS_DEBUG | HAS_SYMS | HAS_LOCALS;
  if (N_DYNAMIC(*execp))
    abfd->flags |= DYNAMIC;

  if ((execp->a_info & MF_SQUEEZED) != 0) /* Squeezed files aren't supported
					     (yet)! */
    {
      bfd_set_error (bfd_error_wrong_format);
      return NULL;
    }
  else if ((execp->a_info & MF_IS_SL) != 0)	/* Nor are shared libraries */
    {
      bfd_set_error (bfd_error_wrong_format);
      return NULL;
    }
  else if (N_MAGIC (*execp) == ZMAGIC)
    {
      abfd->flags |= D_PAGED | WP_TEXT;
      adata (abfd).magic = z_magic;
    }
  else if (N_MAGIC (*execp) == NMAGIC)
    {
      abfd->flags |= WP_TEXT;
      adata (abfd).magic = n_magic;
    }
  else if (N_MAGIC (*execp) == OMAGIC)
    adata (abfd).magic = o_magic;
  else
    {
      /* Should have been checked with N_BADMAG before this routine
         was called.  */
      abort ();
    }

  bfd_get_start_address (abfd) = execp->a_entry;

  obj_aout_symbols (abfd) = (aout_symbol_type *)NULL;
  bfd_get_symcount (abfd) = execp->a_syms / sizeof (struct external_nlist);

  /* The default relocation entry size is that of traditional V7 Unix.  */
  obj_reloc_entry_size (abfd) = RELOC_STD_SIZE;

  /* The default symbol entry size is that of traditional Unix.  */
  obj_symbol_entry_size (abfd) = EXTERNAL_NLIST_SIZE;

  obj_aout_external_syms (abfd) = NULL;
  obj_aout_external_strings (abfd) = NULL;
  obj_aout_sym_hashes (abfd) = NULL;

  if (! NAME(aout,make_sections) (abfd))
    return NULL;

  obj_datasec (abfd)->_raw_size = execp->a_data;
  obj_bsssec (abfd)->_raw_size = execp->a_bss;

  obj_textsec (abfd)->flags =
    (execp->a_trsize != 0
     ? (SEC_ALLOC | SEC_LOAD | SEC_CODE | SEC_HAS_CONTENTS | SEC_RELOC)
     : (SEC_ALLOC | SEC_LOAD | SEC_CODE | SEC_HAS_CONTENTS));
  obj_datasec (abfd)->flags =
    (execp->a_drsize != 0
     ? (SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_HAS_CONTENTS | SEC_RELOC)
     : (SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_HAS_CONTENTS));
  obj_bsssec (abfd)->flags = SEC_ALLOC;

  result = (*callback_to_real_object_p) (abfd);

#if defined(MACH) || defined(STAT_FOR_EXEC)
  /* The original heuristic doesn't work in some important cases. The
   * a.out file has no information about the text start address. For
   * files (like kernels) linked to non-standard addresses (ld -Ttext
   * nnn) the entry point may not be between the default text start
   * (obj_textsec(abfd)->vma) and (obj_textsec(abfd)->vma) + text size
   * This is not just a mach issue. Many kernels are loaded at non
   * standard addresses.
   */
  {
    struct stat stat_buf;
    if (abfd->iostream != NULL
	&& (abfd->flags & BFD_IN_MEMORY) == 0
        && (fstat(fileno((FILE *) (abfd->iostream)), &stat_buf) == 0)
        && ((stat_buf.st_mode & 0111) != 0))
      abfd->flags |= EXEC_P;
  }
#else /* ! MACH */
  /* Now that the segment addresses have been worked out, take a better
     guess at whether the file is executable.  If the entry point
     is within the text segment, assume it is.  (This makes files
     executable even if their entry point address is 0, as long as
     their text starts at zero.)

     At some point we should probably break down and stat the file and
     declare it executable if (one of) its 'x' bits are on...  */
  if ((execp->a_entry >= obj_textsec(abfd)->vma) &&
      (execp->a_entry < obj_textsec(abfd)->vma + obj_textsec(abfd)->_raw_size))
    abfd->flags |= EXEC_P;
#endif /* MACH */
  if (result)
    {
    }
  else
    {
      free (rawptr);
      abfd->tdata.aout_data = oldrawptr;
    }
  return result;
}

static const bfd_target *
MY(object_p) (abfd)
     bfd *abfd;
{
  struct external_exec exec_bytes;      /* Raw exec header from file */
  struct internal_exec exec;            /* Cleaned-up exec header */
  const bfd_target *target;

  if (bfd_read ((PTR) &exec_bytes, 1, EXEC_BYTES_SIZE, abfd)
      != EXEC_BYTES_SIZE) {
    if (bfd_get_error () != bfd_error_system_call)
      bfd_set_error (bfd_error_wrong_format);
    return 0;
  }

  exec.a_info = bfd_h_get_32 (abfd, exec_bytes.e_info);

  if (N_BADMAG (exec)) return 0;
#ifdef MACHTYPE_OK
  if (!(MACHTYPE_OK (N_MACHTYPE (exec)))) return 0;
#endif

  NAME(aout,swap_exec_header_in) (abfd, &exec_bytes, &exec);

  target = riscix_some_aout_object_p (abfd, &exec, MY(callback));

  return target;
}

#include "aout-target.h"