bfdint.texi

这个是LINUX下的GDB调度工具的源码

@samp{_bfd_noarchive}.  Finally, a few targets have unusual archive
handling.

@table @samp
@item _slurp_armap
Read in the archive symbol table, storing it in private BFD data.  This
is normally called from the archive @samp{check_format} routine.  The
corresponding field in the target vector is named
@samp{_bfd_slurp_armap}.

@item _slurp_extended_name_table
Read in the extended name table from the archive, if there is one,
storing it in private BFD data.  This is normally called from the
archive @samp{check_format} routine.  The corresponding field in the
target vector is named @samp{_bfd_slurp_extended_name_table}.

@item construct_extended_name_table
Build and return an extended name table if one is needed to write out
the archive.  This also adjusts the archive headers to refer to the
extended name table appropriately.  This is normally called from the
archive @samp{write_contents} routine.  The corresponding field in the
target vector is named @samp{_bfd_construct_extended_name_table}.

@item _truncate_arname
This copies a file name into an archive header, truncating it as
required.  It is normally called from the archive @samp{write_contents}
routine.  This function is more interesting in targets which do not
support extended name tables, but I think the GNU @samp{ar} program
always uses extended name tables anyhow.  The corresponding field in the
target vector is named @samp{_bfd_truncate_arname}.

@item _write_armap
Write out the archive symbol table using calls to @samp{bfd_bwrite}.
This is normally called from the archive @samp{write_contents} routine.
The corresponding field in the target vector is named @samp{write_armap}
(no leading underscore).

@item _read_ar_hdr
Read and parse an archive header.  This handles expanding the archive
header name into the real file name using the extended name table.  This
is called by routines which read the archive symbol table or the archive
itself.  The corresponding field in the target vector is named
@samp{_bfd_read_ar_hdr_fn}.

@item _openr_next_archived_file
Given an archive and a BFD representing a file stored within the
archive, return a BFD for the next file in the archive.  This is called
via @samp{bfd_openr_next_archived_file}.  The corresponding field in the
target vector is named @samp{openr_next_archived_file} (no leading
underscore).

@item _get_elt_at_index
Given an archive and an index, return a BFD for the file in the archive
corresponding to that entry in the archive symbol table.  This is called
via @samp{bfd_get_elt_at_index}.  The corresponding field in the target
vector is named @samp{_bfd_get_elt_at_index}.

@item _generic_stat_arch_elt
Do a stat on an element of an archive, returning information read from
the archive header (modification time, uid, gid, file mode, size).  This
is called via @samp{bfd_stat_arch_elt}.  The corresponding field in the
target vector is named @samp{_bfd_stat_arch_elt}.

@item _update_armap_timestamp
After the entire contents of an archive have been written out, update
the timestamp of the archive symbol table to be newer than that of the
file.  This is required for a.out style archives.  This is normally
called by the archive @samp{write_contents} routine.  The corresponding
field in the target vector is named @samp{_bfd_update_armap_timestamp}.
@end table

@node BFD target vector symbols
@subsection Symbol table functions
@cindex @samp{BFD_JUMP_TABLE_SYMBOLS}

The @samp{BFD_JUMP_TABLE_SYMBOLS} macro is used for functions which deal
with symbols.

@table @samp
@item _get_symtab_upper_bound
Return a sensible upper bound on the amount of memory which will be
required to read the symbol table.  In practice most targets return the
amount of memory required to hold @samp{asymbol} pointers for all the
symbols plus a trailing @samp{NULL} entry, and store the actual symbol
information in BFD private data.  This is called via
@samp{bfd_get_symtab_upper_bound}.  The corresponding field in the
target vector is named @samp{_bfd_get_symtab_upper_bound}.

@item _canonicalize_symtab
Read in the symbol table.  This is called via
@samp{bfd_canonicalize_symtab}.  The corresponding field in the target
vector is named @samp{_bfd_canonicalize_symtab}.

@item _make_empty_symbol
Create an empty symbol for the BFD.  This is needed because most targets
store extra information with each symbol by allocating a structure
larger than an @samp{asymbol} and storing the extra information at the
end.  This function will allocate the right amount of memory, and return
what looks like a pointer to an empty @samp{asymbol}.  This is called
via @samp{bfd_make_empty_symbol}.  The corresponding field in the target
vector is named @samp{_bfd_make_empty_symbol}.

@item _print_symbol
Print information about the symbol.  This is called via
@samp{bfd_print_symbol}.  One of the arguments indicates what sort of
information should be printed:

@table @samp
@item bfd_print_symbol_name
Just print the symbol name.
@item bfd_print_symbol_more
Print the symbol name and some interesting flags.  I don't think
anything actually uses this.
@item bfd_print_symbol_all
Print all information about the symbol.  This is used by @samp{objdump}
when run with the @samp{-t} option.
@end table
The corresponding field in the target vector is named
@samp{_bfd_print_symbol}.

@item _get_symbol_info
Return a standard set of information about the symbol.  This is called
via @samp{bfd_symbol_info}.  The corresponding field in the target
vector is named @samp{_bfd_get_symbol_info}.

@item _bfd_is_local_label_name
Return whether the given string would normally represent the name of a
local label.  This is called via @samp{bfd_is_local_label} and
@samp{bfd_is_local_label_name}.  Local labels are normally discarded by
the assembler.  In the linker, this defines the difference between the
@samp{-x} and @samp{-X} options.

@item _get_lineno
Return line number information for a symbol.  This is only meaningful
for a COFF target.  This is called when writing out COFF line numbers.

@item _find_nearest_line
Given an address within a section, use the debugging information to find
the matching file name, function name, and line number, if any.  This is
called via @samp{bfd_find_nearest_line}.  The corresponding field in the
target vector is named @samp{_bfd_find_nearest_line}.

@item _bfd_make_debug_symbol
Make a debugging symbol.  This is only meaningful for a COFF target,
where it simply returns a symbol which will be placed in the
@samp{N_DEBUG} section when it is written out.  This is called via
@samp{bfd_make_debug_symbol}.

@item _read_minisymbols
Minisymbols are used to reduce the memory requirements of programs like
@samp{nm}.  A minisymbol is a cookie pointing to internal symbol
information which the caller can use to extract complete symbol
information.  This permits BFD to not convert all the symbols into
generic form, but to instead convert them one at a time.  This is called
via @samp{bfd_read_minisymbols}.  Most targets do not implement this,
and just use generic support which is based on using standard
@samp{asymbol} structures.

@item _minisymbol_to_symbol
Convert a minisymbol to a standard @samp{asymbol}.  This is called via
@samp{bfd_minisymbol_to_symbol}.
@end table

@node BFD target vector relocs
@subsection Relocation support
@cindex @samp{BFD_JUMP_TABLE_RELOCS}

The @samp{BFD_JUMP_TABLE_RELOCS} macro is used for functions which deal
with relocations.

@table @samp
@item _get_reloc_upper_bound
Return a sensible upper bound on the amount of memory which will be
required to read the relocations for a section.  In practice most
targets return the amount of memory required to hold @samp{arelent}
pointers for all the relocations plus a trailing @samp{NULL} entry, and
store the actual relocation information in BFD private data.  This is
called via @samp{bfd_get_reloc_upper_bound}.

@item _canonicalize_reloc
Return the relocation information for a section.  This is called via
@samp{bfd_canonicalize_reloc}.  The corresponding field in the target
vector is named @samp{_bfd_canonicalize_reloc}.

@item _bfd_reloc_type_lookup
Given a relocation code, return the corresponding howto structure
(@pxref{BFD relocation codes}).  This is called via
@samp{bfd_reloc_type_lookup}.  The corresponding field in the target
vector is named @samp{reloc_type_lookup}.
@end table

@node BFD target vector write
@subsection Output functions
@cindex @samp{BFD_JUMP_TABLE_WRITE}

The @samp{BFD_JUMP_TABLE_WRITE} macro is used for functions which deal
with writing out a BFD.

@table @samp
@item _set_arch_mach
Set the architecture and machine number for a BFD.  This is called via
@samp{bfd_set_arch_mach}.  Most targets implement this by calling
@samp{bfd_default_set_arch_mach}.  The corresponding field in the target
vector is named @samp{_bfd_set_arch_mach}.

@item _set_section_contents
Write out the contents of a section.  This is called via
@samp{bfd_set_section_contents}.  The corresponding field in the target
vector is named @samp{_bfd_set_section_contents}.
@end table

@node BFD target vector link
@subsection Linker functions
@cindex @samp{BFD_JUMP_TABLE_LINK}

The @samp{BFD_JUMP_TABLE_LINK} macro is used for functions called by the
linker.

@table @samp
@item _sizeof_headers
Return the size of the header information required for a BFD.  This is
used to implement the @samp{SIZEOF_HEADERS} linker script function.  It
is normally used to align the first section at an efficient position on
the page.  This is called via @samp{bfd_sizeof_headers}.  The
corresponding field in the target vector is named
@samp{_bfd_sizeof_headers}.

@item _bfd_get_relocated_section_contents
Read the contents of a section and apply the relocation information.
This handles both a final link and a relocatable link; in the latter
case, it adjust the relocation information as well.  This is called via
@samp{bfd_get_relocated_section_contents}.  Most targets implement it by
calling @samp{bfd_generic_get_relocated_section_contents}.

@item _bfd_relax_section
Try to use relaxation to shrink the size of a section.  This is called
by the linker when the @samp{-relax} option is used.  This is called via
@samp{bfd_relax_section}.  Most targets do not support any sort of
relaxation.

@item _bfd_link_hash_table_create
Create the symbol hash table to use for the linker.  This linker hook
permits the backend to control the size and information of the elements
in the linker symbol hash table.  This is called via
@samp{bfd_link_hash_table_create}.

@item _bfd_link_add_symbols
Given an object file or an archive, add all symbols into the linker
symbol hash table.  Use callbacks to the linker to include archive
elements in the link.  This is called via @samp{bfd_link_add_symbols}.

@item _bfd_final_link
Finish the linking process.  The linker calls this hook after all of the
input files have been read, when it is ready to finish the link and
generate the output file.  This is called via @samp{bfd_final_link}.

@item _bfd_link_split_section
I don't know what this is for.  Nothing seems to call it.  The only
non-trivial definition is in @file{som.c}.
@end table

@node BFD target vector dynamic
@subsection Dynamic linking information functions
@cindex @samp{BFD_JUMP_TABLE_DYNAMIC}

The @samp{BFD_JUMP_TABLE_DYNAMIC} macro is used for functions which read
dynamic linking information.

@table @samp
@item _get_dynamic_symtab_upper_bound
Return a sensible upper bound on the amount of memory which will be
required to read the dynamic symbol table.  In practice most targets
return the amount of memory required to hold @samp{asymbol} pointers for
all the symbols plus a trailing @samp{NULL} entry, and store the actual
symbol information in BFD private data.  This is called via
@samp{bfd_get_dynamic_symtab_upper_bound}.  The corresponding field in
the target vector is named @samp{_bfd_get_dynamic_symtab_upper_bound}.

@item _canonicalize_dynamic_symtab
Read the dynamic symbol table.  This is called via
@samp{bfd_canonicalize_dynamic_symtab}.  The corresponding field in the
target vector is named @samp{_bfd_canonicalize_dynamic_symtab}.

@item _get_dynamic_reloc_upper_bound
Return a sensible upper bound on the amount of memory which will be
required to read the dynamic relocations.  In practice most targets
return the amount of memory required to hold @samp{arelent} pointers for
all the relocations plus a trailing @samp{NULL} entry, and store the
actual relocation information in BFD private data.  This is called via
@samp{bfd_get_dynamic_reloc_upper_bound}.  The corresponding field in
the target vector is named @samp{_bfd_get_dynamic_reloc_upper_bound}.

@item _canonicalize_dynamic_reloc
Read the dynamic relocations.  This is called via
@samp{bfd_canonicalize_dynamic_reloc}.  The corresponding field in the
target vector is named @samp{_bfd_canonicalize_dynamic_reloc}.
@end table

@node BFD generated files
@section BFD generated files
@cindex generated files in bfd
@cindex bfd generated files

BFD contains several automatically generated files.  This section