| Line 74... |
Line 74... |
types, @file{coff-i960.c} also includes some code to
|
types, @file{coff-i960.c} also includes some code to
|
manipulate the i960 relocs. This code is not in
|
manipulate the i960 relocs. This code is not in
|
@file{coffcode.h} because it would not be used by any other
|
@file{coffcode.h} because it would not be used by any other
|
target.
|
target.
|
|
|
|
@subsubsection Coff long section names
|
|
In the standard Coff object format, section names are limited to
|
|
the eight bytes available in the @code{s_name} field of the
|
|
@code{SCNHDR} section header structure. The format requires the
|
|
field to be NUL-padded, but not necessarily NUL-terminated, so
|
|
the longest section names permitted are a full eight characters.
|
|
|
|
The Microsoft PE variants of the Coff object file format add
|
|
an extension to support the use of long section names. This
|
|
extension is defined in section 4 of the Microsoft PE/COFF
|
|
specification (rev 8.1). If a section name is too long to fit
|
|
into the section header's @code{s_name} field, it is instead
|
|
placed into the string table, and the @code{s_name} field is
|
|
filled with a slash ("/") followed by the ASCII decimal
|
|
representation of the offset of the full name relative to the
|
|
string table base.
|
|
|
|
Note that this implies that the extension can only be used in object
|
|
files, as executables do not contain a string table. The standard
|
|
specifies that long section names from objects emitted into executable
|
|
images are to be truncated.
|
|
|
|
However, as a GNU extension, BFD can generate executable images
|
|
that contain a string table and long section names. This
|
|
would appear to be technically valid, as the standard only says
|
|
that Coff debugging information is deprecated, not forbidden,
|
|
and in practice it works, although some tools that parse PE files
|
|
expecting the MS standard format may become confused; @file{PEview} is
|
|
one known example.
|
|
|
|
The functionality is supported in BFD by code implemented under
|
|
the control of the macro @code{COFF_LONG_SECTION_NAMES}. If not
|
|
defined, the format does not support long section names in any way.
|
|
If defined, it is used to initialise a flag,
|
|
@code{_bfd_coff_long_section_names}, and a hook function pointer,
|
|
@code{_bfd_coff_set_long_section_names}, in the Coff backend data
|
|
structure. The flag controls the generation of long section names
|
|
in output BFDs at runtime; if it is false, as it will be by default
|
|
when generating an executable image, long section names are truncated;
|
|
if true, the long section names extension is employed. The hook
|
|
points to a function that allows the value of the flag to be altered
|
|
at runtime, on formats that support long section names at all; on
|
|
other formats it points to a stub that returns an error indication.
|
|
With input BFDs, the flag is set according to whether any long section
|
|
names are detected while reading the section headers. For a completely
|
|
new BFD, the flag is set to the default for the target format. This
|
|
information can be used by a client of the BFD library when deciding
|
|
what output format to generate, and means that a BFD that is opened
|
|
for read and subsequently converted to a writeable BFD and modified
|
|
in-place will retain whatever format it had on input.
|
|
|
|
If @code{COFF_LONG_SECTION_NAMES} is simply defined (blank), or is
|
|
defined to the value "1", then long section names are enabled by
|
|
default; if it is defined to the value zero, they are disabled by
|
|
default (but still accepted in input BFDs). The header @file{coffcode.h}
|
|
defines a macro, @code{COFF_DEFAULT_LONG_SECTION_NAMES}, which is
|
|
used in the backends to initialise the backend data structure fields
|
|
appropriately; see the comments for further detail.
|
|
|
@subsubsection Bit twiddling
|
@subsubsection Bit twiddling
|
Each flavour of coff supported in BFD has its own header file
|
Each flavour of coff supported in BFD has its own header file
|
describing the external layout of the structures. There is also
|
describing the external layout of the structures. There is also
|
an internal description of the coff layout, in
|
an internal description of the coff layout, in
|
@file{coff/internal.h}. A major function of the
|
@file{coff/internal.h}. A major function of the
|
| Line 324... |
Line 383... |
unsigned int _bfd_auxesz;
|
unsigned int _bfd_auxesz;
|
unsigned int _bfd_relsz;
|
unsigned int _bfd_relsz;
|
unsigned int _bfd_linesz;
|
unsigned int _bfd_linesz;
|
unsigned int _bfd_filnmlen;
|
unsigned int _bfd_filnmlen;
|
bfd_boolean _bfd_coff_long_filenames;
|
bfd_boolean _bfd_coff_long_filenames;
|
|
|
bfd_boolean _bfd_coff_long_section_names;
|
bfd_boolean _bfd_coff_long_section_names;
|
|
bfd_boolean (*_bfd_coff_set_long_section_names)
|
|
(bfd *, int);
|
|
|
unsigned int _bfd_coff_default_section_alignment_power;
|
unsigned int _bfd_coff_default_section_alignment_power;
|
bfd_boolean _bfd_coff_force_symnames_in_strings;
|
bfd_boolean _bfd_coff_force_symnames_in_strings;
|
unsigned int _bfd_coff_debug_string_prefix_length;
|
unsigned int _bfd_coff_debug_string_prefix_length;
|
|
|
void (*_bfd_coff_swap_filehdr_in)
|
void (*_bfd_coff_swap_filehdr_in)
|
| Line 411... |
Line 474... |
(bfd *, struct coff_final_link_info *);
|
(bfd *, struct coff_final_link_info *);
|
|
|
bfd_boolean (*_bfd_coff_final_link_postscript)
|
bfd_boolean (*_bfd_coff_final_link_postscript)
|
(bfd *, struct coff_final_link_info *);
|
(bfd *, struct coff_final_link_info *);
|
|
|
|
bfd_boolean (*_bfd_coff_print_pdata)
|
|
(bfd *, void *);
|
|
|
@} bfd_coff_backend_data;
|
@} bfd_coff_backend_data;
|
|
|
#define coff_backend_info(abfd) \
|
#define coff_backend_info(abfd) \
|
((bfd_coff_backend_data *) (abfd)->xvec->backend_data)
|
((bfd_coff_backend_data *) (abfd)->xvec->backend_data)
|
|
|
| Line 458... |
Line 524... |
#define bfd_coff_filnmlen(abfd) (coff_backend_info (abfd)->_bfd_filnmlen)
|
#define bfd_coff_filnmlen(abfd) (coff_backend_info (abfd)->_bfd_filnmlen)
|
#define bfd_coff_long_filenames(abfd) \
|
#define bfd_coff_long_filenames(abfd) \
|
(coff_backend_info (abfd)->_bfd_coff_long_filenames)
|
(coff_backend_info (abfd)->_bfd_coff_long_filenames)
|
#define bfd_coff_long_section_names(abfd) \
|
#define bfd_coff_long_section_names(abfd) \
|
(coff_backend_info (abfd)->_bfd_coff_long_section_names)
|
(coff_backend_info (abfd)->_bfd_coff_long_section_names)
|
|
#define bfd_coff_set_long_section_names(abfd, enable) \
|
|
((coff_backend_info (abfd)->_bfd_coff_set_long_section_names) (abfd, enable))
|
#define bfd_coff_default_section_alignment_power(abfd) \
|
#define bfd_coff_default_section_alignment_power(abfd) \
|
(coff_backend_info (abfd)->_bfd_coff_default_section_alignment_power)
|
(coff_backend_info (abfd)->_bfd_coff_default_section_alignment_power)
|
#define bfd_coff_swap_filehdr_in(abfd, i,o) \
|
#define bfd_coff_swap_filehdr_in(abfd, i,o) \
|
((coff_backend_info (abfd)->_bfd_coff_swap_filehdr_in) (abfd, i, o))
|
((coff_backend_info (abfd)->_bfd_coff_swap_filehdr_in) (abfd, i, o))
|
|
|
| Line 543... |
Line 611... |
#define bfd_coff_link_output_has_begun(a,p) \
|
#define bfd_coff_link_output_has_begun(a,p) \
|
((coff_backend_info (a)->_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) \
|
#define bfd_coff_final_link_postscript(a,p) \
|
((coff_backend_info (a)->_bfd_coff_final_link_postscript) (a, p))
|
((coff_backend_info (a)->_bfd_coff_final_link_postscript) (a, p))
|
|
|
|
#define bfd_coff_have_print_pdata(a) \
|
|
(coff_backend_info (a)->_bfd_coff_print_pdata)
|
|
#define bfd_coff_print_pdata(a,p) \
|
|
((coff_backend_info (a)->_bfd_coff_print_pdata) (a, p))
|
|
|
|
/* Macro: Returns true if the bfd is a PE executable as opposed to a
|
|
PE object file. */
|
|
#define bfd_pei_p(abfd) \
|
|
(CONST_STRNEQ ((abfd)->xvec->name, "pei-"))
|
@end example
|
@end example
|
@subsubsection Writing relocations
|
@subsubsection Writing relocations
|
To write relocations, the back end steps though the
|
To write relocations, the back end steps though the
|
canonical relocation table and create an
|
canonical relocation table and create an
|
@code{internal_reloc}. The symbol index to use is removed from
|
@code{internal_reloc}. The symbol index to use is removed from
|
