xref: /openbsd-current/gnu/usr.bin/binutils-2.17/bfd/doc/format.texi

@section File formats
A format is a BFD concept of high level file contents type. The
formats supported by BFD are:

@itemize @bullet

@item
@code{bfd_object}
@end itemize
The BFD may contain data, symbols, relocations and debug info.

@itemize @bullet

@item
@code{bfd_archive}
@end itemize
The BFD contains other BFDs and an optional index.

@itemize @bullet

@item
@code{bfd_core}
@end itemize
The BFD contains the result of an executable core dump.

@subsection File format functions


@findex bfd_check_format
@subsubsection @code{bfd_check_format}
@strong{Synopsis}
@example
bfd_boolean bfd_check_format (bfd *abfd, bfd_format format);
@end example
@strong{Description}@*
Verify if the file attached to the BFD @var{abfd} is compatible
with the format @var{format} (i.e., one of @code{bfd_object},
@code{bfd_archive} or @code{bfd_core}).

If the BFD has been set to a specific target before the
call, only the named target and format combination is
checked. If the target has not been set, or has been set to
@code{default}, then all the known target backends is
interrogated to determine a match.  If the default target
matches, it is used.  If not, exactly one target must recognize
the file, or an error results.

The function returns @code{TRUE} on success, otherwise @code{FALSE}
with one of the following error codes:

@itemize @bullet

@item
@code{bfd_error_invalid_operation} -
if @code{format} is not one of @code{bfd_object}, @code{bfd_archive} or
@code{bfd_core}.

@item
@code{bfd_error_system_call} -
if an error occured during a read - even some file mismatches
can cause bfd_error_system_calls.

@item
@code{file_not_recognised} -
none of the backends recognised the file format.

@item
@code{bfd_error_file_ambiguously_recognized} -
more than one backend recognised the file format.
@end itemize

@findex bfd_check_format_matches
@subsubsection @code{bfd_check_format_matches}
@strong{Synopsis}
@example
bfd_boolean bfd_check_format_matches
   (bfd *abfd, bfd_format format, char ***matching);
@end example
@strong{Description}@*
Like @code{bfd_check_format}, except when it returns FALSE with
@code{bfd_errno} set to @code{bfd_error_file_ambiguously_recognized}.  In that
case, if @var{matching} is not NULL, it will be filled in with
a NULL-terminated list of the names of the formats that matched,
allocated with @code{malloc}.
Then the user may choose a format and try again.

When done with the list that @var{matching} points to, the caller
should free it.

@findex bfd_set_format
@subsubsection @code{bfd_set_format}
@strong{Synopsis}
@example
bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
@end example
@strong{Description}@*
This function sets the file format of the BFD @var{abfd} to the
format @var{format}. If the target set in the BFD does not
support the format requested, the format is invalid, or the BFD
is not open for writing, then an error occurs.

@findex bfd_format_string
@subsubsection @code{bfd_format_string}
@strong{Synopsis}
@example
const char *bfd_format_string (bfd_format format);
@end example
@strong{Description}@*
Return a pointer to a const string
@code{invalid}, @code{object}, @code{archive}, @code{core}, or @code{unknown},
depending upon the value of @var{format}.