coffcode.texi

这个是LINUX下的GDB调度工具的源码

    PARAMS ((bfd *, PTR, PTR));

  unsigned int (*_bfd_coff_swap_reloc_out)
    PARAMS ((bfd *, PTR, PTR));

  unsigned int (*_bfd_coff_swap_filehdr_out)
    PARAMS ((bfd *, PTR, PTR));

  unsigned int (*_bfd_coff_swap_aouthdr_out)
    PARAMS ((bfd *, PTR, PTR));

  unsigned int (*_bfd_coff_swap_scnhdr_out)
    PARAMS ((bfd *, PTR, PTR));

  unsigned int _bfd_filhsz;
  unsigned int _bfd_aoutsz;
  unsigned int _bfd_scnhsz;
  unsigned int _bfd_symesz;
  unsigned int _bfd_auxesz;
  unsigned int _bfd_relsz;
  unsigned int _bfd_linesz;
  unsigned int _bfd_filnmlen;
  bfd_boolean _bfd_coff_long_filenames;
  bfd_boolean _bfd_coff_long_section_names;
  unsigned int _bfd_coff_default_section_alignment_power;
  bfd_boolean _bfd_coff_force_symnames_in_strings;
  unsigned int _bfd_coff_debug_string_prefix_length;

  void (*_bfd_coff_swap_filehdr_in)
    PARAMS ((bfd *, PTR, PTR));

  void (*_bfd_coff_swap_aouthdr_in)
    PARAMS ((bfd *, PTR, PTR));

  void (*_bfd_coff_swap_scnhdr_in)
    PARAMS ((bfd *, PTR, PTR));

  void (*_bfd_coff_swap_reloc_in)
    PARAMS ((bfd *abfd, PTR, PTR));

  bfd_boolean (*_bfd_coff_bad_format_hook)
    PARAMS ((bfd *, PTR));

  bfd_boolean (*_bfd_coff_set_arch_mach_hook)
    PARAMS ((bfd *, PTR));

  PTR (*_bfd_coff_mkobject_hook)
    PARAMS ((bfd *, PTR, PTR));

  bfd_boolean (*_bfd_styp_to_sec_flags_hook)
    PARAMS ((bfd *, PTR, const char *, asection *, flagword *));

  void (*_bfd_set_alignment_hook)
    PARAMS ((bfd *, asection *, PTR));

  bfd_boolean (*_bfd_coff_slurp_symbol_table)
    PARAMS ((bfd *));

  bfd_boolean (*_bfd_coff_symname_in_debug)
    PARAMS ((bfd *, struct internal_syment *));

  bfd_boolean (*_bfd_coff_pointerize_aux_hook)
    PARAMS ((bfd *, combined_entry_type *, combined_entry_type *,
            unsigned int, combined_entry_type *));

  bfd_boolean (*_bfd_coff_print_aux)
    PARAMS ((bfd *, FILE *, combined_entry_type *, combined_entry_type *,
            combined_entry_type *, unsigned int));

  void (*_bfd_coff_reloc16_extra_cases)
    PARAMS ((bfd *, struct bfd_link_info *, struct bfd_link_order *, arelent *,
           bfd_byte *, unsigned int *, unsigned int *));

  int (*_bfd_coff_reloc16_estimate)
    PARAMS ((bfd *, asection *, arelent *, unsigned int,
            struct bfd_link_info *));

  enum coff_symbol_classification (*_bfd_coff_classify_symbol)
    PARAMS ((bfd *, struct internal_syment *));

  bfd_boolean (*_bfd_coff_compute_section_file_positions)
    PARAMS ((bfd *));

  bfd_boolean (*_bfd_coff_start_final_link)
    PARAMS ((bfd *, struct bfd_link_info *));

  bfd_boolean (*_bfd_coff_relocate_section)
    PARAMS ((bfd *, struct bfd_link_info *, bfd *, asection *, bfd_byte *,
            struct internal_reloc *, struct internal_syment *, asection **));

  reloc_howto_type *(*_bfd_coff_rtype_to_howto)
    PARAMS ((bfd *, asection *, struct internal_reloc *,
            struct coff_link_hash_entry *, struct internal_syment *,
            bfd_vma *));

  bfd_boolean (*_bfd_coff_adjust_symndx)
    PARAMS ((bfd *, struct bfd_link_info *, bfd *, asection *,
            struct internal_reloc *, bfd_boolean *));

  bfd_boolean (*_bfd_coff_link_add_one_symbol)
    PARAMS ((struct bfd_link_info *, bfd *, const char *, flagword,
            asection *, bfd_vma, const char *, bfd_boolean, bfd_boolean,
            struct bfd_link_hash_entry **));

  bfd_boolean (*_bfd_coff_link_output_has_begun)
    PARAMS ((bfd *, struct coff_final_link_info *));

  bfd_boolean (*_bfd_coff_final_link_postscript)
    PARAMS ((bfd *, struct coff_final_link_info *));

@} bfd_coff_backend_data;

#define coff_backend_info(abfd) \
  ((bfd_coff_backend_data *) (abfd)->xvec->backend_data)

#define bfd_coff_swap_aux_in(a,e,t,c,ind,num,i) \
  ((coff_backend_info (a)->_bfd_coff_swap_aux_in) (a,e,t,c,ind,num,i))

#define bfd_coff_swap_sym_in(a,e,i) \
  ((coff_backend_info (a)->_bfd_coff_swap_sym_in) (a,e,i))

#define bfd_coff_swap_lineno_in(a,e,i) \
  ((coff_backend_info ( a)->_bfd_coff_swap_lineno_in) (a,e,i))

#define bfd_coff_swap_reloc_out(abfd, i, o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_reloc_out) (abfd, i, o))

#define bfd_coff_swap_lineno_out(abfd, i, o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_lineno_out) (abfd, i, o))

#define bfd_coff_swap_aux_out(a,i,t,c,ind,num,o) \
  ((coff_backend_info (a)->_bfd_coff_swap_aux_out) (a,i,t,c,ind,num,o))

#define bfd_coff_swap_sym_out(abfd, i,o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_sym_out) (abfd, i, o))

#define bfd_coff_swap_scnhdr_out(abfd, i,o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_scnhdr_out) (abfd, i, o))

#define bfd_coff_swap_filehdr_out(abfd, i,o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_filehdr_out) (abfd, i, o))

#define bfd_coff_swap_aouthdr_out(abfd, i,o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_aouthdr_out) (abfd, i, o))

#define bfd_coff_filhsz(abfd) (coff_backend_info (abfd)->_bfd_filhsz)
#define bfd_coff_aoutsz(abfd) (coff_backend_info (abfd)->_bfd_aoutsz)
#define bfd_coff_scnhsz(abfd) (coff_backend_info (abfd)->_bfd_scnhsz)
#define bfd_coff_symesz(abfd) (coff_backend_info (abfd)->_bfd_symesz)
#define bfd_coff_auxesz(abfd) (coff_backend_info (abfd)->_bfd_auxesz)
#define bfd_coff_relsz(abfd)  (coff_backend_info (abfd)->_bfd_relsz)
#define bfd_coff_linesz(abfd) (coff_backend_info (abfd)->_bfd_linesz)
#define bfd_coff_filnmlen(abfd) (coff_backend_info (abfd)->_bfd_filnmlen)
#define bfd_coff_long_filenames(abfd) \
  (coff_backend_info (abfd)->_bfd_coff_long_filenames)
#define bfd_coff_long_section_names(abfd) \
  (coff_backend_info (abfd)->_bfd_coff_long_section_names)
#define bfd_coff_default_section_alignment_power(abfd) \
  (coff_backend_info (abfd)->_bfd_coff_default_section_alignment_power)
#define bfd_coff_swap_filehdr_in(abfd, i,o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_filehdr_in) (abfd, i, o))

#define bfd_coff_swap_aouthdr_in(abfd, i,o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_aouthdr_in) (abfd, i, o))

#define bfd_coff_swap_scnhdr_in(abfd, i,o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_scnhdr_in) (abfd, i, o))

#define bfd_coff_swap_reloc_in(abfd, i, o) \
  ((coff_backend_info (abfd)->_bfd_coff_swap_reloc_in) (abfd, i, o))

#define bfd_coff_bad_format_hook(abfd, filehdr) \
  ((coff_backend_info (abfd)->_bfd_coff_bad_format_hook) (abfd, filehdr))

#define bfd_coff_set_arch_mach_hook(abfd, filehdr)\
  ((coff_backend_info (abfd)->_bfd_coff_set_arch_mach_hook) (abfd, filehdr))
#define bfd_coff_mkobject_hook(abfd, filehdr, aouthdr)\
  ((coff_backend_info (abfd)->_bfd_coff_mkobject_hook)\
   (abfd, filehdr, aouthdr))

#define bfd_coff_styp_to_sec_flags_hook(abfd, scnhdr, name, section, flags_ptr)\
  ((coff_backend_info (abfd)->_bfd_styp_to_sec_flags_hook)\
   (abfd, scnhdr, name, section, flags_ptr))

#define bfd_coff_set_alignment_hook(abfd, sec, scnhdr)\
  ((coff_backend_info (abfd)->_bfd_set_alignment_hook) (abfd, sec, scnhdr))

#define bfd_coff_slurp_symbol_table(abfd)\
  ((coff_backend_info (abfd)->_bfd_coff_slurp_symbol_table) (abfd))

#define bfd_coff_symname_in_debug(abfd, sym)\
  ((coff_backend_info (abfd)->_bfd_coff_symname_in_debug) (abfd, sym))

#define bfd_coff_force_symnames_in_strings(abfd)\
  (coff_backend_info (abfd)->_bfd_coff_force_symnames_in_strings)

#define bfd_coff_debug_string_prefix_length(abfd)\
  (coff_backend_info (abfd)->_bfd_coff_debug_string_prefix_length)

#define bfd_coff_print_aux(abfd, file, base, symbol, aux, indaux)\
  ((coff_backend_info (abfd)->_bfd_coff_print_aux)\
   (abfd, file, base, symbol, aux, indaux))

#define bfd_coff_reloc16_extra_cases(abfd, link_info, link_order,\
                                     reloc, data, src_ptr, dst_ptr)\
  ((coff_backend_info (abfd)->_bfd_coff_reloc16_extra_cases)\
   (abfd, link_info, link_order, reloc, data, src_ptr, dst_ptr))

#define bfd_coff_reloc16_estimate(abfd, section, reloc, shrink, link_info)\
  ((coff_backend_info (abfd)->_bfd_coff_reloc16_estimate)\
   (abfd, section, reloc, shrink, link_info))

#define bfd_coff_classify_symbol(abfd, sym)\
  ((coff_backend_info (abfd)->_bfd_coff_classify_symbol)\
   (abfd, sym))

#define bfd_coff_compute_section_file_positions(abfd)\
  ((coff_backend_info (abfd)->_bfd_coff_compute_section_file_positions)\
   (abfd))

#define bfd_coff_start_final_link(obfd, info)\
  ((coff_backend_info (obfd)->_bfd_coff_start_final_link)\
   (obfd, info))
#define bfd_coff_relocate_section(obfd,info,ibfd,o,con,rel,isyms,secs)\
  ((coff_backend_info (ibfd)->_bfd_coff_relocate_section)\
   (obfd, info, ibfd, o, con, rel, isyms, secs))
#define bfd_coff_rtype_to_howto(abfd, sec, rel, h, sym, addendp)\
  ((coff_backend_info (abfd)->_bfd_coff_rtype_to_howto)\
   (abfd, sec, rel, h, sym, addendp))
#define bfd_coff_adjust_symndx(obfd, info, ibfd, sec, rel, adjustedp)\
  ((coff_backend_info (abfd)->_bfd_coff_adjust_symndx)\
   (obfd, info, ibfd, sec, rel, adjustedp))
#define bfd_coff_link_add_one_symbol(info, abfd, name, flags, section,\
                                     value, string, cp, coll, hashp)\
  ((coff_backend_info (abfd)->_bfd_coff_link_add_one_symbol)\
   (info, abfd, name, flags, section, value, string, cp, coll, hashp))

#define bfd_coff_link_output_has_begun(a,p) \
  ((coff_backend_info (a)->_bfd_coff_link_output_has_begun) (a,p))
#define bfd_coff_final_link_postscript(a,p) \
  ((coff_backend_info (a)->_bfd_coff_final_link_postscript) (a,p))

@end example
@subsubsection Writing relocations
To write relocations, the back end steps though the
canonical relocation table and create an
@code{internal_reloc}. The symbol index to use is removed from
the @code{offset} field in the symbol table supplied.  The
address comes directly from the sum of the section base
address and the relocation offset; the type is dug directly
from the howto field.  Then the @code{internal_reloc} is
swapped into the shape of an @code{external_reloc} and written
out to disk.

@subsubsection Reading linenumbers
Creating the linenumber table is done by reading in the entire
coff linenumber table, and creating another table for internal use.

A coff linenumber table is structured so that each function
is marked as having a line number of 0. Each line within the
function is an offset from the first line in the function. The
base of the line number information for the table is stored in
the symbol associated with the function.

Note: The PE format uses line number 0 for a flag indicating a
new source file.

The information is copied from the external to the internal
table, and each symbol which marks a function is marked by
pointing its...

How does this work ?

@subsubsection Reading relocations
Coff relocations are easily transformed into the internal BFD form
(@code{arelent}).

Reading a coff relocation table is done in the following stages:

@itemize @bullet

@item
Read the entire coff relocation table into memory.

@item
Process each relocation in turn; first swap it from the
external to the internal form.

@item
Turn the symbol referenced in the relocation's symbol index
into a pointer into the canonical symbol table.
This table is the same as the one returned by a call to
@code{bfd_canonicalize_symtab}. The back end will call that
routine and save the result if a canonicalization hasn't been done.

@item
The reloc index is turned into a pointer to a howto
structure, in a back end specific way. For instance, the 386
and 960 use the @code{r_type} to directly produce an index
into a howto table vector; the 88k subtracts a number from the
@code{r_type} field and creates an addend field.
@end itemize