479 lines
18 KiB
Plaintext
479 lines
18 KiB
Plaintext
@section Targets
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@strong{Description}@*
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Each port of BFD to a different machine requries the creation
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of a target back end. All the back end provides to the root
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part of BFD is a structure containing pointers to functions
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which perform certain low level operations on files. BFD
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translates the applications's requests through a pointer into
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calls to the back end routines.
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When a file is opened with @code{bfd_openr}, its format and
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target are unknown. BFD uses various mechanisms to determine
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how to interpret the file. The operations performed are:
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@itemize @bullet
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@item
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Create a BFD by calling the internal routine
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@code{_bfd_new_bfd}, then call @code{bfd_find_target} with the
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target string supplied to @code{bfd_openr} and the new BFD pointer.
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@item
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If a null target string was provided to @code{bfd_find_target},
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look up the environment variable @code{GNUTARGET} and use
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that as the target string.
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@item
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If the target string is still @code{NULL}, or the target string is
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@code{default}, then use the first item in the target vector
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as the target type, and set @code{target_defaulted} in the BFD to
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cause @code{bfd_check_format} to loop through all the targets.
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@xref{bfd_target}. @xref{Formats}.
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@item
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Otherwise, inspect the elements in the target vector
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one by one, until a match on target name is found. When found,
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use it.
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@item
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Otherwise return the error @code{bfd_error_invalid_target} to
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@code{bfd_openr}.
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@item
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@code{bfd_openr} attempts to open the file using
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@code{bfd_open_file}, and returns the BFD.
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@end itemize
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Once the BFD has been opened and the target selected, the file
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format may be determined. This is done by calling
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@code{bfd_check_format} on the BFD with a suggested format.
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If @code{target_defaulted} has been set, each possible target
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type is tried to see if it recognizes the specified format.
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@code{bfd_check_format} returns @code{true} when the caller guesses right.
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@menu
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* bfd_target::
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@end menu
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@node bfd_target, , Targets, Targets
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@subsection bfd_target
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@strong{Description}@*
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This structure contains everything that BFD knows about a
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target. It includes things like its byte order, name, and which
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routines to call to do various operations.
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Every BFD points to a target structure with its @code{xvec}
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member.
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The macros below are used to dispatch to functions through the
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@code{bfd_target} vector. They are used in a number of macros further
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down in @file{bfd.h}, and are also used when calling various
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routines by hand inside the BFD implementation. The @var{arglist}
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argument must be parenthesized; it contains all the arguments
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to the called function.
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They make the documentation (more) unpleasant to read, so if
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someone wants to fix this and not break the above, please do.
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@example
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#define BFD_SEND(bfd, message, arglist) \
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((*((bfd)->xvec->message)) arglist)
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#ifdef DEBUG_BFD_SEND
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#undef BFD_SEND
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#define BFD_SEND(bfd, message, arglist) \
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(((bfd) && (bfd)->xvec && (bfd)->xvec->message) ? \
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((*((bfd)->xvec->message)) arglist) : \
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(bfd_assert (__FILE__,__LINE__), NULL))
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#endif
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@end example
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For operations which index on the BFD format:
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@example
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#define BFD_SEND_FMT(bfd, message, arglist) \
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(((bfd)->xvec->message[(int)((bfd)->format)]) arglist)
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#ifdef DEBUG_BFD_SEND
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#undef BFD_SEND_FMT
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#define BFD_SEND_FMT(bfd, message, arglist) \
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(((bfd) && (bfd)->xvec && (bfd)->xvec->message) ? \
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(((bfd)->xvec->message[(int)((bfd)->format)]) arglist) : \
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(bfd_assert (__FILE__,__LINE__), NULL))
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#endif
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@end example
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This is the structure which defines the type of BFD this is. The
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@code{xvec} member of the struct @code{bfd} itself points here. Each
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module that implements access to a different target under BFD,
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defines one of these.
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FIXME, these names should be rationalised with the names of
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the entry points which call them. Too bad we can't have one
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macro to define them both!
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@example
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enum bfd_flavour @{
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bfd_target_unknown_flavour,
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bfd_target_aout_flavour,
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bfd_target_coff_flavour,
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bfd_target_ecoff_flavour,
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bfd_target_elf_flavour,
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bfd_target_ieee_flavour,
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bfd_target_nlm_flavour,
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bfd_target_oasys_flavour,
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bfd_target_tekhex_flavour,
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bfd_target_srec_flavour,
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bfd_target_ihex_flavour,
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bfd_target_som_flavour,
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bfd_target_os9k_flavour,
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bfd_target_versados_flavour,
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bfd_target_msdos_flavour,
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bfd_target_evax_flavour
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@};
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enum bfd_endian @{ BFD_ENDIAN_BIG, BFD_ENDIAN_LITTLE, BFD_ENDIAN_UNKNOWN @};
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/* Forward declaration. */
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typedef struct bfd_link_info _bfd_link_info;
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typedef struct bfd_target
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@{
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@end example
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Identifies the kind of target, e.g., SunOS4, Ultrix, etc.
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@example
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char *name;
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@end example
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The "flavour" of a back end is a general indication about the contents
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of a file.
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@example
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enum bfd_flavour flavour;
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@end example
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The order of bytes within the data area of a file.
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@example
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enum bfd_endian byteorder;
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@end example
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The order of bytes within the header parts of a file.
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@example
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enum bfd_endian header_byteorder;
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@end example
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A mask of all the flags which an executable may have set -
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from the set @code{BFD_NO_FLAGS}, @code{HAS_RELOC}, ...@code{D_PAGED}.
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@example
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flagword object_flags;
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@end example
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A mask of all the flags which a section may have set - from
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the set @code{SEC_NO_FLAGS}, @code{SEC_ALLOC}, ...@code{SET_NEVER_LOAD}.
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@example
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flagword section_flags;
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@end example
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The character normally found at the front of a symbol
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(if any), perhaps `_'.
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@example
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char symbol_leading_char;
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@end example
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The pad character for file names within an archive header.
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@example
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char ar_pad_char;
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@end example
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The maximum number of characters in an archive header.
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@example
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unsigned short ar_max_namelen;
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@end example
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Entries for byte swapping for data. These are different from the other
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entry points, since they don't take a BFD asthe first argument.
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Certain other handlers could do the same.
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@example
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bfd_vma (*bfd_getx64) PARAMS ((const bfd_byte *));
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bfd_signed_vma (*bfd_getx_signed_64) PARAMS ((const bfd_byte *));
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void (*bfd_putx64) PARAMS ((bfd_vma, bfd_byte *));
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bfd_vma (*bfd_getx32) PARAMS ((const bfd_byte *));
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bfd_signed_vma (*bfd_getx_signed_32) PARAMS ((const bfd_byte *));
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void (*bfd_putx32) PARAMS ((bfd_vma, bfd_byte *));
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bfd_vma (*bfd_getx16) PARAMS ((const bfd_byte *));
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bfd_signed_vma (*bfd_getx_signed_16) PARAMS ((const bfd_byte *));
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void (*bfd_putx16) PARAMS ((bfd_vma, bfd_byte *));
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@end example
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Byte swapping for the headers
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@example
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bfd_vma (*bfd_h_getx64) PARAMS ((const bfd_byte *));
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bfd_signed_vma (*bfd_h_getx_signed_64) PARAMS ((const bfd_byte *));
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void (*bfd_h_putx64) PARAMS ((bfd_vma, bfd_byte *));
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bfd_vma (*bfd_h_getx32) PARAMS ((const bfd_byte *));
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bfd_signed_vma (*bfd_h_getx_signed_32) PARAMS ((const bfd_byte *));
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void (*bfd_h_putx32) PARAMS ((bfd_vma, bfd_byte *));
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bfd_vma (*bfd_h_getx16) PARAMS ((const bfd_byte *));
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bfd_signed_vma (*bfd_h_getx_signed_16) PARAMS ((const bfd_byte *));
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void (*bfd_h_putx16) PARAMS ((bfd_vma, bfd_byte *));
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@end example
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Format dependent routines: these are vectors of entry points
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within the target vector structure, one for each format to check.
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Check the format of a file being read. Return a @code{bfd_target *} or zero.
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@example
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const struct bfd_target *(*_bfd_check_format[bfd_type_end]) PARAMS ((bfd *));
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@end example
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Set the format of a file being written.
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@example
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boolean (*_bfd_set_format[bfd_type_end]) PARAMS ((bfd *));
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@end example
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Write cached information into a file being written, at @code{bfd_close}.
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@example
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boolean (*_bfd_write_contents[bfd_type_end]) PARAMS ((bfd *));
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@end example
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The general target vector.
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@example
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/* Generic entry points. */
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#define BFD_JUMP_TABLE_GENERIC(NAME)\
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CAT(NAME,_close_and_cleanup),\
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CAT(NAME,_bfd_free_cached_info),\
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CAT(NAME,_new_section_hook),\
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CAT(NAME,_get_section_contents),\
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CAT(NAME,_get_section_contents_in_window)
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/* Called when the BFD is being closed to do any necessary cleanup. */
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boolean (*_close_and_cleanup) PARAMS ((bfd *));
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/* Ask the BFD to free all cached information. */
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boolean (*_bfd_free_cached_info) PARAMS ((bfd *));
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/* Called when a new section is created. */
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boolean (*_new_section_hook) PARAMS ((bfd *, sec_ptr));
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/* Read the contents of a section. */
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boolean (*_bfd_get_section_contents) PARAMS ((bfd *, sec_ptr, PTR,
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file_ptr, bfd_size_type));
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boolean (*_bfd_get_section_contents_in_window)
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PARAMS ((bfd *, sec_ptr, bfd_window *,
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file_ptr, bfd_size_type));
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/* Entry points to copy private data. */
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#define BFD_JUMP_TABLE_COPY(NAME)\
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CAT(NAME,_bfd_copy_private_bfd_data),\
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CAT(NAME,_bfd_merge_private_bfd_data),\
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CAT(NAME,_bfd_copy_private_section_data),\
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CAT(NAME,_bfd_copy_private_symbol_data),\
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CAT(NAME,_bfd_set_private_flags),\
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CAT(NAME,_bfd_print_private_bfd_data)\
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/* Called to copy BFD general private data from one object file
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to another. */
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boolean (*_bfd_copy_private_bfd_data) PARAMS ((bfd *, bfd *));
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/* Called to merge BFD general private data from one object file
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to a common output file when linking. */
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boolean (*_bfd_merge_private_bfd_data) PARAMS ((bfd *, bfd *));
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/* Called to copy BFD private section data from one object file
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to another. */
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boolean (*_bfd_copy_private_section_data) PARAMS ((bfd *, sec_ptr,
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bfd *, sec_ptr));
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/* Called to copy BFD private symbol data from one symbol
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to another. */
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boolean (*_bfd_copy_private_symbol_data) PARAMS ((bfd *, asymbol *,
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bfd *, asymbol *));
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/* Called to set private backend flags */
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boolean (*_bfd_set_private_flags) PARAMS ((bfd *, flagword));
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/* Called to print private BFD data */
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boolean (*_bfd_print_private_bfd_data) PARAMS ((bfd *, PTR));
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/* Core file entry points. */
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#define BFD_JUMP_TABLE_CORE(NAME)\
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CAT(NAME,_core_file_failing_command),\
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CAT(NAME,_core_file_failing_signal),\
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CAT(NAME,_core_file_matches_executable_p)
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char * (*_core_file_failing_command) PARAMS ((bfd *));
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int (*_core_file_failing_signal) PARAMS ((bfd *));
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boolean (*_core_file_matches_executable_p) PARAMS ((bfd *, bfd *));
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/* Archive entry points. */
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#define BFD_JUMP_TABLE_ARCHIVE(NAME)\
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CAT(NAME,_slurp_armap),\
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CAT(NAME,_slurp_extended_name_table),\
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CAT(NAME,_construct_extended_name_table),\
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CAT(NAME,_truncate_arname),\
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CAT(NAME,_write_armap),\
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CAT(NAME,_read_ar_hdr),\
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CAT(NAME,_openr_next_archived_file),\
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CAT(NAME,_get_elt_at_index),\
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CAT(NAME,_generic_stat_arch_elt),\
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CAT(NAME,_update_armap_timestamp)
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boolean (*_bfd_slurp_armap) PARAMS ((bfd *));
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boolean (*_bfd_slurp_extended_name_table) PARAMS ((bfd *));
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boolean (*_bfd_construct_extended_name_table)
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PARAMS ((bfd *, char **, bfd_size_type *, const char **));
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void (*_bfd_truncate_arname) PARAMS ((bfd *, CONST char *, char *));
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boolean (*write_armap) PARAMS ((bfd *arch,
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unsigned int elength,
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struct orl *map,
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unsigned int orl_count,
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int stridx));
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PTR (*_bfd_read_ar_hdr_fn) PARAMS ((bfd *));
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bfd * (*openr_next_archived_file) PARAMS ((bfd *arch, bfd *prev));
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#define bfd_get_elt_at_index(b,i) BFD_SEND(b, _bfd_get_elt_at_index, (b,i))
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bfd * (*_bfd_get_elt_at_index) PARAMS ((bfd *, symindex));
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int (*_bfd_stat_arch_elt) PARAMS ((bfd *, struct stat *));
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boolean (*_bfd_update_armap_timestamp) PARAMS ((bfd *));
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/* Entry points used for symbols. */
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#define BFD_JUMP_TABLE_SYMBOLS(NAME)\
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CAT(NAME,_get_symtab_upper_bound),\
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CAT(NAME,_get_symtab),\
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CAT(NAME,_make_empty_symbol),\
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CAT(NAME,_print_symbol),\
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CAT(NAME,_get_symbol_info),\
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CAT(NAME,_bfd_is_local_label_name),\
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CAT(NAME,_get_lineno),\
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CAT(NAME,_find_nearest_line),\
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CAT(NAME,_bfd_make_debug_symbol),\
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CAT(NAME,_read_minisymbols),\
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CAT(NAME,_minisymbol_to_symbol)
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long (*_bfd_get_symtab_upper_bound) PARAMS ((bfd *));
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long (*_bfd_canonicalize_symtab) PARAMS ((bfd *,
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struct symbol_cache_entry **));
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struct symbol_cache_entry *
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(*_bfd_make_empty_symbol) PARAMS ((bfd *));
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void (*_bfd_print_symbol) PARAMS ((bfd *, PTR,
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struct symbol_cache_entry *,
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bfd_print_symbol_type));
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#define bfd_print_symbol(b,p,s,e) BFD_SEND(b, _bfd_print_symbol, (b,p,s,e))
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void (*_bfd_get_symbol_info) PARAMS ((bfd *,
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struct symbol_cache_entry *,
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symbol_info *));
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#define bfd_get_symbol_info(b,p,e) BFD_SEND(b, _bfd_get_symbol_info, (b,p,e))
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boolean (*_bfd_is_local_label_name) PARAMS ((bfd *, const char *));
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alent * (*_get_lineno) PARAMS ((bfd *, struct symbol_cache_entry *));
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boolean (*_bfd_find_nearest_line) PARAMS ((bfd *abfd,
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struct sec *section, struct symbol_cache_entry **symbols,
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bfd_vma offset, CONST char **file, CONST char **func,
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unsigned int *line));
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/* Back-door to allow format-aware applications to create debug symbols
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while using BFD for everything else. Currently used by the assembler
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when creating COFF files. */
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asymbol * (*_bfd_make_debug_symbol) PARAMS ((
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bfd *abfd,
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void *ptr,
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unsigned long size));
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#define bfd_read_minisymbols(b, d, m, s) \
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BFD_SEND (b, _read_minisymbols, (b, d, m, s))
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long (*_read_minisymbols) PARAMS ((bfd *, boolean, PTR *,
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unsigned int *));
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#define bfd_minisymbol_to_symbol(b, d, m, f) \
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BFD_SEND (b, _minisymbol_to_symbol, (b, d, m, f))
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asymbol *(*_minisymbol_to_symbol) PARAMS ((bfd *, boolean, const PTR,
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asymbol *));
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/* Routines for relocs. */
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#define BFD_JUMP_TABLE_RELOCS(NAME)\
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CAT(NAME,_get_reloc_upper_bound),\
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CAT(NAME,_canonicalize_reloc),\
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CAT(NAME,_bfd_reloc_type_lookup)
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long (*_get_reloc_upper_bound) PARAMS ((bfd *, sec_ptr));
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long (*_bfd_canonicalize_reloc) PARAMS ((bfd *, sec_ptr, arelent **,
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struct symbol_cache_entry **));
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/* See documentation on reloc types. */
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reloc_howto_type *
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(*reloc_type_lookup) PARAMS ((bfd *abfd,
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bfd_reloc_code_real_type code));
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/* Routines used when writing an object file. */
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#define BFD_JUMP_TABLE_WRITE(NAME)\
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CAT(NAME,_set_arch_mach),\
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CAT(NAME,_set_section_contents)
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boolean (*_bfd_set_arch_mach) PARAMS ((bfd *, enum bfd_architecture,
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unsigned long));
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boolean (*_bfd_set_section_contents) PARAMS ((bfd *, sec_ptr, PTR,
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file_ptr, bfd_size_type));
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/* Routines used by the linker. */
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#define BFD_JUMP_TABLE_LINK(NAME)\
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CAT(NAME,_sizeof_headers),\
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CAT(NAME,_bfd_get_relocated_section_contents),\
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CAT(NAME,_bfd_relax_section),\
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CAT(NAME,_bfd_link_hash_table_create),\
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CAT(NAME,_bfd_link_add_symbols),\
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CAT(NAME,_bfd_final_link),\
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CAT(NAME,_bfd_link_split_section)
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int (*_bfd_sizeof_headers) PARAMS ((bfd *, boolean));
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bfd_byte * (*_bfd_get_relocated_section_contents) PARAMS ((bfd *,
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struct bfd_link_info *, struct bfd_link_order *,
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bfd_byte *data, boolean relocateable,
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struct symbol_cache_entry **));
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boolean (*_bfd_relax_section) PARAMS ((bfd *, struct sec *,
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struct bfd_link_info *, boolean *again));
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/* Create a hash table for the linker. Different backends store
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different information in this table. */
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struct bfd_link_hash_table *(*_bfd_link_hash_table_create) PARAMS ((bfd *));
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/* Add symbols from this object file into the hash table. */
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boolean (*_bfd_link_add_symbols) PARAMS ((bfd *, struct bfd_link_info *));
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/* Do a link based on the link_order structures attached to each
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section of the BFD. */
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boolean (*_bfd_final_link) PARAMS ((bfd *, struct bfd_link_info *));
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/* Should this section be split up into smaller pieces during linking. */
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boolean (*_bfd_link_split_section) PARAMS ((bfd *, struct sec *));
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/* Routines to handle dynamic symbols and relocs. */
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#define BFD_JUMP_TABLE_DYNAMIC(NAME)\
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CAT(NAME,_get_dynamic_symtab_upper_bound),\
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CAT(NAME,_canonicalize_dynamic_symtab),\
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CAT(NAME,_get_dynamic_reloc_upper_bound),\
|
|
CAT(NAME,_canonicalize_dynamic_reloc)
|
|
/* Get the amount of memory required to hold the dynamic symbols. */
|
|
long (*_bfd_get_dynamic_symtab_upper_bound) PARAMS ((bfd *));
|
|
/* Read in the dynamic symbols. */
|
|
long (*_bfd_canonicalize_dynamic_symtab)
|
|
PARAMS ((bfd *, struct symbol_cache_entry **));
|
|
/* Get the amount of memory required to hold the dynamic relocs. */
|
|
long (*_bfd_get_dynamic_reloc_upper_bound) PARAMS ((bfd *));
|
|
/* Read in the dynamic relocs. */
|
|
long (*_bfd_canonicalize_dynamic_reloc)
|
|
PARAMS ((bfd *, arelent **, struct symbol_cache_entry **));
|
|
|
|
@end example
|
|
Data for use by back-end routines, which isn't generic enough to belong
|
|
in this structure.
|
|
@example
|
|
PTR backend_data;
|
|
@} bfd_target;
|
|
@end example
|
|
|
|
@findex bfd_set_default_target
|
|
@subsubsection @code{bfd_set_default_target}
|
|
@strong{Synopsis}
|
|
@example
|
|
boolean bfd_set_default_target (const char *name);
|
|
@end example
|
|
@strong{Description}@*
|
|
Set the default target vector to use when recognizing a BFD.
|
|
This takes the name of the target, which may be a BFD target
|
|
name or a configuration triplet.
|
|
|
|
@findex bfd_find_target
|
|
@subsubsection @code{bfd_find_target}
|
|
@strong{Synopsis}
|
|
@example
|
|
const bfd_target *bfd_find_target(CONST char *target_name, bfd *abfd);
|
|
@end example
|
|
@strong{Description}@*
|
|
Return a pointer to the transfer vector for the object target
|
|
named @var{target_name}. If @var{target_name} is @code{NULL}, choose the
|
|
one in the environment variable @code{GNUTARGET}; if that is null or not
|
|
defined, then choose the first entry in the target list.
|
|
Passing in the string "default" or setting the environment
|
|
variable to "default" will cause the first entry in the target
|
|
list to be returned, and "target_defaulted" will be set in the
|
|
BFD. This causes @code{bfd_check_format} to loop over all the
|
|
targets to find the one that matches the file being read.
|
|
|
|
@findex bfd_target_list
|
|
@subsubsection @code{bfd_target_list}
|
|
@strong{Synopsis}
|
|
@example
|
|
const char **bfd_target_list(void);
|
|
@end example
|
|
@strong{Description}@*
|
|
Return a freshly malloced NULL-terminated
|
|
vector of the names of all the valid BFD targets. Do not
|
|
modify the names.
|
|
|