bout.c

早期freebsd实现

  int incode_mask;
  int size_mask;
  bfd_vma prev_addr = 0;
  unsigned int count;
  size_t  reloc_size;
  struct relocation_info *relocs;
  arelent *reloc_cache;

  if (asect->relocation) return true;
  if (!aout_32_slurp_symbol_table (abfd)) return false;

  if (asect == obj_datasec (abfd)) {
    reloc_size = exec_hdr(abfd)->a_drsize;
    goto doit;
  }

  if (asect == obj_textsec (abfd)) {
    reloc_size = exec_hdr(abfd)->a_trsize;
    goto doit;
  }

  bfd_error = invalid_operation;
  return false;

 doit:
  bfd_seek (abfd, (file_ptr)(asect->rel_filepos),  SEEK_SET);
  count = reloc_size / sizeof (struct relocation_info);

  relocs = (struct relocation_info *) bfd_xmalloc (reloc_size);
  if (!relocs) {
    bfd_error = no_memory;
    return false;
  }
  reloc_cache = (arelent *) bfd_xmalloc ((count+1) * sizeof (arelent));
  if (!reloc_cache) {
    free ((char*)relocs);
    bfd_error = no_memory;
    return false;
  }

  if (bfd_read ((PTR) relocs, 1, reloc_size, abfd) != reloc_size) {
    bfd_error = system_call_error;
    free (reloc_cache);
    free (relocs);
    return false;
  }


  
  if (abfd->xvec->header_byteorder_big_p) {
    /* big-endian bit field allocation order */
    pcrel_mask  = 0x80;
    extern_mask = 0x10;
    incode_mask = 0x08;
    callj_mask  = 0x02;
    size_mask =   0x20;
    length_shift = 5;
  } else {
    /* little-endian bit field allocation order */
    pcrel_mask  = 0x01;
    extern_mask = 0x08;
    incode_mask = 0x10;
    callj_mask  = 0x40;
    size_mask   = 0x02;
    length_shift = 1;
  }

  for (rptr = relocs, cache_ptr = reloc_cache, counter = 0;
       counter < count;
       counter++, rptr++, cache_ptr++) 
  {
    unsigned char *raw = (unsigned char *)rptr;
    unsigned int symnum;
    cache_ptr->address = bfd_h_get_32 (abfd, raw + 0);
    cache_ptr->howto = 0;
    if (abfd->xvec->header_byteorder_big_p) 
    {
      symnum = (raw[4] << 16) | (raw[5] << 8) | raw[6];
    } 
    else
    {
      symnum = (raw[6] << 16) | (raw[5] << 8) | raw[4];
    }

    if (raw[7] & extern_mask) 
    {
      /* if this is set then the r_index is a index into the symbol table;
       * if the bit is not set then r_index contains a section map.
       * we either fill in the sym entry with a pointer to the symbol,
       * or point to the correct section
       */
      cache_ptr->sym_ptr_ptr = symbols + symnum;
      cache_ptr->addend = 0;
    } else 
    {
      /* in a.out symbols are relative to the beginning of the
       * file rather than sections ?
       * (look in translate_from_native_sym_flags)
       * the reloc entry addend has added to it the offset into the
       * file of the data, so subtract the base to make the reloc
       * section relative */
      int s;
      {
	/* sign-extend symnum from 24 bits to whatever host uses */
	s = symnum;
	if (s & (1 << 23))
	  s |= (~0) << 24;
      }
      cache_ptr->sym_ptr_ptr = (asymbol **)NULL;
      switch (s)
      {
       case N_TEXT:
       case N_TEXT | N_EXT:
	cache_ptr->sym_ptr_ptr = obj_textsec(abfd)->symbol_ptr_ptr;
	cache_ptr->addend = - obj_textsec(abfd)->vma;
	break;
       case N_DATA:
       case N_DATA | N_EXT:
	cache_ptr->sym_ptr_ptr = obj_datasec(abfd)->symbol_ptr_ptr;
	cache_ptr->addend = - obj_datasec(abfd)->vma;
	break;
       case N_BSS:
       case N_BSS | N_EXT:
	cache_ptr->sym_ptr_ptr = obj_bsssec(abfd)->symbol_ptr_ptr;
	cache_ptr->addend =  - obj_bsssec(abfd)->vma;
	break;
       case N_ABS:
       case N_ABS | N_EXT:
	cache_ptr->sym_ptr_ptr = obj_bsssec(abfd)->symbol_ptr_ptr;
	cache_ptr->addend = 0;
	break;
      case -2: /* .align */
	if (raw[7] & pcrel_mask)
	  {
	    cache_ptr->howto = &howto_align_table[(raw[7] >> length_shift) & 3];
	    cache_ptr->sym_ptr_ptr = &bfd_abs_symbol;
	  }
	else
	  {
	    /* .org? */
	    abort ();
	  }
	cache_ptr->addend = 0;
	break;
       default:
	BFD_ASSERT(0);
	break;
      }
	
    }

    /* the i960 only has a few relocation types:
       abs 32-bit and pcrel 24bit.   except for callj's!  */
    if (cache_ptr->howto != 0)
      ;
    else if (raw[7] & callj_mask)
    {
      cache_ptr->howto = &howto_reloc_callj;
    }
    else if ( raw[7] & pcrel_mask)
    {
      if (raw[7] & size_mask)
       cache_ptr->howto = &howto_reloc_pcrel13;
      else
       cache_ptr->howto = &howto_reloc_pcrel24;
    }
    else 
    {
      if (raw[7] & incode_mask) 
      {
	cache_ptr->howto = &howto_reloc_abs32code;
      }
      else 
      {
	cache_ptr->howto = &howto_reloc_abs32;
      }
    }
    if (cache_ptr->address < prev_addr) 
    {
      /* Ouch! this reloc is out of order, insert into the right place
       */
      arelent tmp;
      arelent *cursor = cache_ptr-1;
      bfd_vma stop = cache_ptr->address;
      tmp  = *cache_ptr;
      while (cursor->address > stop && cursor >= reloc_cache)
      {
	cursor[1] = cursor[0];
	cursor--;
      } 
      cursor[1] = tmp;
    }
    else 
    {
      prev_addr = cache_ptr->address;
    }
  }


  free (relocs);
  asect->relocation = reloc_cache;
  asect->reloc_count = count;


  return true;
}


static boolean
b_out_squirt_out_relocs (abfd, section)
     bfd *abfd;
     asection *section;
{

  arelent **generic;
  int r_extern;
  int r_idx;
  int incode_mask;  
  int len_1;
  unsigned int count = section->reloc_count;
  struct relocation_info *native, *natptr;
  size_t natsize = count * sizeof (struct relocation_info);
  int extern_mask, pcrel_mask,  len_2, callj_mask;
  if (count == 0) return true;
  generic   = section->orelocation;
  native = ((struct relocation_info *) bfd_xmalloc (natsize));
  if (!native) {
    bfd_error = no_memory;
    return false;
  }

  if (abfd->xvec->header_byteorder_big_p) 
  {
    /* Big-endian bit field allocation order */
    pcrel_mask  = 0x80;
    extern_mask = 0x10;
    len_2       = 0x40;
    len_1       = 0x20;
    callj_mask  = 0x02;
    incode_mask = 0x08;
  } 
  else 
  {
    /* Little-endian bit field allocation order */
    pcrel_mask  = 0x01;
    extern_mask = 0x08;
    len_2       = 0x04;
    len_1       = 0x02;
    callj_mask  = 0x40;
    incode_mask = 0x10;
  }

  for (natptr = native; count > 0; --count, ++natptr, ++generic) 
  {
    arelent *g = *generic;
    unsigned char *raw = (unsigned char *)natptr;
    asymbol *sym = *(g->sym_ptr_ptr);
      
    asection *output_section = sym->section->output_section;
    bfd_h_put_32(abfd, g->address, raw);  
    /* Find a type in the output format which matches the input howto - 
     * at the moment we assume input format == output format FIXME!!
     */
    /* FIXME:  Need callj stuff here, and to check the howto entries to
       be sure they are real for this architecture.  */
    if (g->howto== &howto_reloc_callj) 
    {
      raw[7] = callj_mask + pcrel_mask + len_2;
    }
    else if (g->howto == &howto_reloc_pcrel24) 
    {
      raw[7] = pcrel_mask + len_2;
    }
    else if (g->howto == &howto_reloc_pcrel13) 
    {
      raw[7] = pcrel_mask + len_1;
    }
    else if (g->howto == &howto_reloc_abs32code) 
    {
      raw[7] = len_2 + incode_mask;
    }
    else {
      raw[7] = len_2;
    }
    if (output_section == &bfd_com_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_idx = 0;
	r_extern = 0;
       }
      else 
      {
	/* Fill in symbol */

	r_extern = 1;
	r_idx =  stoi((*(g->sym_ptr_ptr))->flags);
      }
    }
    else 
    {
      /* Just an ordinary section */
      r_extern = 0;
      r_idx  = output_section->target_index;      
    }

    if (abfd->xvec->header_byteorder_big_p) {
      raw[4] = (unsigned char) (r_idx >> 16);
      raw[5] = (unsigned char) (r_idx >>  8);
      raw[6] = (unsigned char) (r_idx     );
    } else {
      raw[6] = (unsigned char) (r_idx >> 16);
      raw[5] = (unsigned char) (r_idx>>  8);
      raw[4] = (unsigned char) (r_idx     );
    }  
    if (r_extern)
     raw[7] |= extern_mask; 
  }

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

  return true;
}

/* This is stupid.  This function should be a boolean predicate */
static unsigned int
b_out_canonicalize_reloc (abfd, section, relptr, symbols)
     bfd *abfd;
     sec_ptr section;
     arelent **relptr;
     asymbol **symbols;
{
  arelent *tblptr = section->relocation;
  unsigned int count = 0;

 if (!(tblptr || b_out_slurp_reloc_table (abfd, section, symbols))) return 0;
  tblptr = section->relocation;
 if (!tblptr) return 0;

  for (; count++ < section->reloc_count;)
    *relptr++ = tblptr++;

  *relptr = 0;

  return section->reloc_count;
}

static unsigned int
b_out_get_reloc_upper_bound (abfd, asect)
     bfd *abfd;
     sec_ptr asect;
{
  if (bfd_get_format (abfd) != bfd_object) {
    bfd_error = invalid_operation;
    return 0;
  }

  if (asect == obj_datasec (abfd))
    return (sizeof (arelent *) *
	    ((exec_hdr(abfd)->a_drsize / sizeof (struct relocation_info))
	     +1));

  if (asect == obj_textsec (abfd))
    return (sizeof (arelent *) *
	    ((exec_hdr(abfd)->a_trsize / sizeof (struct relocation_info))
	     +1));

  bfd_error = invalid_operation;
  return 0;
}

static boolean
b_out_set_section_contents (abfd, section, location, offset, count)
     bfd *abfd;
     sec_ptr section;
     unsigned char *location;
     file_ptr offset;
      int count;
{

  if (abfd->output_has_begun == false) { /* set by bfd.c handler */
    if ((obj_textsec (abfd) == NULL) || (obj_datasec (abfd) == NULL) /*||
        (obj_textsec (abfd)->_cooked_size == 0) || (obj_datasec (abfd)->_cooked_size == 0)*/) {
      bfd_error = invalid_operation;
      return false;
    }

    obj_textsec (abfd)->filepos = sizeof(struct internal_exec);
    obj_datasec(abfd)->filepos = obj_textsec(abfd)->filepos 
                                 +  obj_textsec (abfd)->_raw_size;

  }
  /* regardless, once we know what we're doing, we might as well get going */
  bfd_seek (abfd, section->filepos + offset, SEEK_SET);

  if (count != 0) {
    return (bfd_write ((PTR)location, 1, count, abfd) == count) ?true:false;
  }
  return true;
}

static boolean
b_out_set_arch_mach (abfd, arch, machine)
     bfd *abfd;
     enum bfd_architecture arch;
     unsigned long machine;
{
  bfd_default_set_arch_mach(abfd, arch, machine);

  if (arch == bfd_arch_unknown)	/* Unknown machine arch is OK */
    return true;
  if (arch == bfd_arch_i960)	/* i960 default is OK */
    switch (machine) {
    case bfd_mach_i960_core:
    case bfd_mach_i960_kb_sb:
    case bfd_mach_i960_mc:
    case bfd_mach_i960_xa:
    case bfd_mach_i960_ca:
    case bfd_mach_i960_ka_sa:
    case 0:
      return true;
    default:
      return false;
    }

  return false;