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Diffstat (limited to 'contrib/binutils/bfd/doc/bfd.texi')
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diff --git a/contrib/binutils/bfd/doc/bfd.texi b/contrib/binutils/bfd/doc/bfd.texi new file mode 100644 index 000000000000..ea0ca9e56dc9 --- /dev/null +++ b/contrib/binutils/bfd/doc/bfd.texi @@ -0,0 +1,585 @@ +@section @code{typedef bfd} +A BFD has type @code{bfd}; objects of this type are the +cornerstone of any application using BFD. Using BFD +consists of making references though the BFD and to data in the BFD. + +Here is the structure that defines the type @code{bfd}. It +contains the major data about the file and pointers +to the rest of the data. +@* +. +@example +struct _bfd +@{ + /* The filename the application opened the BFD with. */ + CONST char *filename; + + /* A pointer to the target jump table. */ + const struct bfd_target *xvec; + + /* To avoid dragging too many header files into every file that + includes `@code{bfd.h}', IOSTREAM has been declared as a "char + *", and MTIME as a "long". Their correct types, to which they + are cast when used, are "FILE *" and "time_t". The iostream + is the result of an fopen on the filename. However, if the + BFD_IN_MEMORY flag is set, then iostream is actually a pointer + to a bfd_in_memory struct. */ + PTR iostream; + + /* Is the file descriptor being cached? That is, can it be closed as + needed, and re-opened when accessed later? */ + + boolean cacheable; + + /* Marks whether there was a default target specified when the + BFD was opened. This is used to select which matching algorithm + to use to choose the back end. */ + + boolean target_defaulted; + + /* The caching routines use these to maintain a + least-recently-used list of BFDs */ + + struct _bfd *lru_prev, *lru_next; + + /* When a file is closed by the caching routines, BFD retains + state information on the file here: */ + + file_ptr where; + + /* and here: (``once'' means at least once) */ + + boolean opened_once; + + /* Set if we have a locally maintained mtime value, rather than + getting it from the file each time: */ + + boolean mtime_set; + + /* File modified time, if mtime_set is true: */ + + long mtime; + + /* Reserved for an unimplemented file locking extension.*/ + + int ifd; + + /* The format which belongs to the BFD. (object, core, etc.) */ + + bfd_format format; + + /* The direction the BFD was opened with*/ + + enum bfd_direction @{no_direction = 0, + read_direction = 1, + write_direction = 2, + both_direction = 3@} direction; + + /* Format_specific flags*/ + + flagword flags; + + /* Currently my_archive is tested before adding origin to + anything. I believe that this can become always an add of + origin, with origin set to 0 for non archive files. */ + + file_ptr origin; + + /* Remember when output has begun, to stop strange things + from happening. */ + boolean output_has_begun; + + /* Pointer to linked list of sections*/ + struct sec *sections; + + /* The number of sections */ + unsigned int section_count; + + /* Stuff only useful for object files: + The start address. */ + bfd_vma start_address; + + /* Used for input and output*/ + unsigned int symcount; + + /* Symbol table for output BFD (with symcount entries) */ + struct symbol_cache_entry **outsymbols; + + /* Pointer to structure which contains architecture information*/ + const struct bfd_arch_info *arch_info; + + /* Stuff only useful for archives:*/ + PTR arelt_data; + struct _bfd *my_archive; /* The containing archive BFD. */ + struct _bfd *next; /* The next BFD in the archive. */ + struct _bfd *archive_head; /* The first BFD in the archive. */ + boolean has_armap; + + /* A chain of BFD structures involved in a link. */ + struct _bfd *link_next; + + /* A field used by _bfd_generic_link_add_archive_symbols. This will + be used only for archive elements. */ + int archive_pass; + + /* Used by the back end to hold private data. */ + + union + @{ + struct aout_data_struct *aout_data; + struct artdata *aout_ar_data; + struct _oasys_data *oasys_obj_data; + struct _oasys_ar_data *oasys_ar_data; + struct coff_tdata *coff_obj_data; + struct pe_tdata *pe_obj_data; + struct xcoff_tdata *xcoff_obj_data; + struct ecoff_tdata *ecoff_obj_data; + struct ieee_data_struct *ieee_data; + struct ieee_ar_data_struct *ieee_ar_data; + struct srec_data_struct *srec_data; + struct ihex_data_struct *ihex_data; + struct tekhex_data_struct *tekhex_data; + struct elf_obj_tdata *elf_obj_data; + struct nlm_obj_tdata *nlm_obj_data; + struct bout_data_struct *bout_data; + struct sun_core_struct *sun_core_data; + struct trad_core_struct *trad_core_data; + struct som_data_struct *som_data; + struct hpux_core_struct *hpux_core_data; + struct hppabsd_core_struct *hppabsd_core_data; + struct sgi_core_struct *sgi_core_data; + struct lynx_core_struct *lynx_core_data; + struct osf_core_struct *osf_core_data; + struct cisco_core_struct *cisco_core_data; + struct versados_data_struct *versados_data; + struct netbsd_core_struct *netbsd_core_data; + PTR any; + @} tdata; + + /* Used by the application to hold private data*/ + PTR usrdata; + + /* Where all the allocated stuff under this BFD goes. This is a + struct objalloc *, but we use PTR to avoid requiring the inclusion of + objalloc.h. */ + PTR memory; +@}; + +@end example +@section Error reporting +Most BFD functions return nonzero on success (check their +individual documentation for precise semantics). On an error, +they call @code{bfd_set_error} to set an error condition that callers +can check by calling @code{bfd_get_error}. +If that returns @code{bfd_error_system_call}, then check +@code{errno}. + +The easiest way to report a BFD error to the user is to +use @code{bfd_perror}. +@* +@subsection Type @code{bfd_error_type} +The values returned by @code{bfd_get_error} are defined by the +enumerated type @code{bfd_error_type}. +@* +. +@example +typedef enum bfd_error +@{ + bfd_error_no_error = 0, + bfd_error_system_call, + bfd_error_invalid_target, + bfd_error_wrong_format, + bfd_error_invalid_operation, + bfd_error_no_memory, + bfd_error_no_symbols, + bfd_error_no_armap, + bfd_error_no_more_archived_files, + bfd_error_malformed_archive, + bfd_error_file_not_recognized, + bfd_error_file_ambiguously_recognized, + bfd_error_no_contents, + bfd_error_nonrepresentable_section, + bfd_error_no_debug_section, + bfd_error_bad_value, + bfd_error_file_truncated, + bfd_error_file_too_big, + bfd_error_invalid_error_code +@} bfd_error_type; + +@end example +@findex bfd_get_error +@subsubsection @code{bfd_get_error} +@strong{Synopsis} +@example +bfd_error_type bfd_get_error (void); +@end example +@strong{Description}@* +Return the current BFD error condition. +@* +@findex bfd_set_error +@subsubsection @code{bfd_set_error} +@strong{Synopsis} +@example +void bfd_set_error (bfd_error_type error_tag); +@end example +@strong{Description}@* +Set the BFD error condition to be @var{error_tag}. +@* +@findex bfd_errmsg +@subsubsection @code{bfd_errmsg} +@strong{Synopsis} +@example +CONST char *bfd_errmsg (bfd_error_type error_tag); +@end example +@strong{Description}@* +Return a string describing the error @var{error_tag}, or +the system error if @var{error_tag} is @code{bfd_error_system_call}. +@* +@findex bfd_perror +@subsubsection @code{bfd_perror} +@strong{Synopsis} +@example +void bfd_perror (CONST char *message); +@end example +@strong{Description}@* +Print to the standard error stream a string describing the +last BFD error that occurred, or the last system error if +the last BFD error was a system call failure. If @var{message} +is non-NULL and non-empty, the error string printed is preceded +by @var{message}, a colon, and a space. It is followed by a newline. +@* +@subsection BFD error handler +Some BFD functions want to print messages describing the +problem. They call a BFD error handler function. This +function may be overriden by the program. + +The BFD error handler acts like printf. +@* +. +@example +typedef void (*bfd_error_handler_type) PARAMS ((const char *, ...)); + +@end example +@findex bfd_set_error_handler +@subsubsection @code{bfd_set_error_handler} +@strong{Synopsis} +@example +bfd_error_handler_type bfd_set_error_handler (bfd_error_handler_type); +@end example +@strong{Description}@* +Set the BFD error handler function. Returns the previous +function. +@* +@findex bfd_set_error_program_name +@subsubsection @code{bfd_set_error_program_name} +@strong{Synopsis} +@example +void bfd_set_error_program_name (const char *); +@end example +@strong{Description}@* +Set the program name to use when printing a BFD error. This +is printed before the error message followed by a colon and +space. The string must not be changed after it is passed to +this function. +@* +@section Symbols + +@* +@findex bfd_get_reloc_upper_bound +@subsubsection @code{bfd_get_reloc_upper_bound} +@strong{Synopsis} +@example +long bfd_get_reloc_upper_bound(bfd *abfd, asection *sect); +@end example +@strong{Description}@* +Return the number of bytes required to store the +relocation information associated with section @var{sect} +attached to bfd @var{abfd}. If an error occurs, return -1. +@* +@findex bfd_canonicalize_reloc +@subsubsection @code{bfd_canonicalize_reloc} +@strong{Synopsis} +@example +long bfd_canonicalize_reloc + (bfd *abfd, + asection *sec, + arelent **loc, + asymbol **syms); +@end example +@strong{Description}@* +Call the back end associated with the open BFD +@var{abfd} and translate the external form of the relocation +information attached to @var{sec} into the internal canonical +form. Place the table into memory at @var{loc}, which has +been preallocated, usually by a call to +@code{bfd_get_reloc_upper_bound}. Returns the number of relocs, or +-1 on error. + +The @var{syms} table is also needed for horrible internal magic +reasons. +@* +@findex bfd_set_reloc +@subsubsection @code{bfd_set_reloc} +@strong{Synopsis} +@example +void bfd_set_reloc + (bfd *abfd, asection *sec, arelent **rel, unsigned int count) +@end example +@strong{Description}@* +Set the relocation pointer and count within +section @var{sec} to the values @var{rel} and @var{count}. +The argument @var{abfd} is ignored. +@* +@findex bfd_set_file_flags +@subsubsection @code{bfd_set_file_flags} +@strong{Synopsis} +@example +boolean bfd_set_file_flags(bfd *abfd, flagword flags); +@end example +@strong{Description}@* +Set the flag word in the BFD @var{abfd} to the value @var{flags}. + +Possible errors are: +@itemize @bullet + +@item +@code{bfd_error_wrong_format} - The target bfd was not of object format. +@item +@code{bfd_error_invalid_operation} - The target bfd was open for reading. +@item +@code{bfd_error_invalid_operation} - +The flag word contained a bit which was not applicable to the +type of file. E.g., an attempt was made to set the @code{D_PAGED} bit +on a BFD format which does not support demand paging. +@end itemize +@* +@findex bfd_set_start_address +@subsubsection @code{bfd_set_start_address} +@strong{Synopsis} +@example +boolean bfd_set_start_address(bfd *abfd, bfd_vma vma); +@end example +@strong{Description}@* +Make @var{vma} the entry point of output BFD @var{abfd}. +@* +@strong{Returns}@* +Returns @code{true} on success, @code{false} otherwise. +@* +@findex bfd_get_mtime +@subsubsection @code{bfd_get_mtime} +@strong{Synopsis} +@example +long bfd_get_mtime(bfd *abfd); +@end example +@strong{Description}@* +Return the file modification time (as read from the file system, or +from the archive header for archive members). +@* +@findex bfd_get_size +@subsubsection @code{bfd_get_size} +@strong{Synopsis} +@example +long bfd_get_size(bfd *abfd); +@end example +@strong{Description}@* +Return the file size (as read from file system) for the file +associated with BFD @var{abfd}. + +The initial motivation for, and use of, this routine is not +so we can get the exact size of the object the BFD applies to, since +that might not be generally possible (archive members for example). +It would be ideal if someone could eventually modify +it so that such results were guaranteed. + +Instead, we want to ask questions like "is this NNN byte sized +object I'm about to try read from file offset YYY reasonable?" +As as example of where we might do this, some object formats +use string tables for which the first @code{sizeof(long)} bytes of the +table contain the size of the table itself, including the size bytes. +If an application tries to read what it thinks is one of these +string tables, without some way to validate the size, and for +some reason the size is wrong (byte swapping error, wrong location +for the string table, etc.), the only clue is likely to be a read +error when it tries to read the table, or a "virtual memory +exhausted" error when it tries to allocate 15 bazillon bytes +of space for the 15 bazillon byte table it is about to read. +This function at least allows us to answer the quesion, "is the +size reasonable?". +@* +@findex bfd_get_gp_size +@subsubsection @code{bfd_get_gp_size} +@strong{Synopsis} +@example +int bfd_get_gp_size(bfd *abfd); +@end example +@strong{Description}@* +Return the maximum size of objects to be optimized using the GP +register under MIPS ECOFF. This is typically set by the @code{-G} +argument to the compiler, assembler or linker. +@* +@findex bfd_set_gp_size +@subsubsection @code{bfd_set_gp_size} +@strong{Synopsis} +@example +void bfd_set_gp_size(bfd *abfd, int i); +@end example +@strong{Description}@* +Set the maximum size of objects to be optimized using the GP +register under ECOFF or MIPS ELF. This is typically set by +the @code{-G} argument to the compiler, assembler or linker. +@* +@findex bfd_scan_vma +@subsubsection @code{bfd_scan_vma} +@strong{Synopsis} +@example +bfd_vma bfd_scan_vma(CONST char *string, CONST char **end, int base); +@end example +@strong{Description}@* +Convert, like @code{strtoul}, a numerical expression +@var{string} into a @code{bfd_vma} integer, and return that integer. +(Though without as many bells and whistles as @code{strtoul}.) +The expression is assumed to be unsigned (i.e., positive). +If given a @var{base}, it is used as the base for conversion. +A base of 0 causes the function to interpret the string +in hex if a leading "0x" or "0X" is found, otherwise +in octal if a leading zero is found, otherwise in decimal. + +Overflow is not detected. +@* +@findex bfd_copy_private_bfd_data +@subsubsection @code{bfd_copy_private_bfd_data} +@strong{Synopsis} +@example +boolean bfd_copy_private_bfd_data(bfd *ibfd, bfd *obfd); +@end example +@strong{Description}@* +Copy private BFD information from the BFD @var{ibfd} to the +the BFD @var{obfd}. Return @code{true} on success, @code{false} on error. +Possible error returns are: + +@itemize @bullet + +@item +@code{bfd_error_no_memory} - +Not enough memory exists to create private data for @var{obfd}. +@end itemize +@example +#define bfd_copy_private_bfd_data(ibfd, obfd) \ + BFD_SEND (obfd, _bfd_copy_private_bfd_data, \ + (ibfd, obfd)) +@end example +@* +@findex bfd_merge_private_bfd_data +@subsubsection @code{bfd_merge_private_bfd_data} +@strong{Synopsis} +@example +boolean bfd_merge_private_bfd_data(bfd *ibfd, bfd *obfd); +@end example +@strong{Description}@* +Merge private BFD information from the BFD @var{ibfd} to the +the output file BFD @var{obfd} when linking. Return @code{true} +on success, @code{false} on error. Possible error returns are: + +@itemize @bullet + +@item +@code{bfd_error_no_memory} - +Not enough memory exists to create private data for @var{obfd}. +@end itemize +@example +#define bfd_merge_private_bfd_data(ibfd, obfd) \ + BFD_SEND (obfd, _bfd_merge_private_bfd_data, \ + (ibfd, obfd)) +@end example +@* +@findex bfd_set_private_flags +@subsubsection @code{bfd_set_private_flags} +@strong{Synopsis} +@example +boolean bfd_set_private_flags(bfd *abfd, flagword flags); +@end example +@strong{Description}@* +Set private BFD flag information in the BFD @var{abfd}. +Return @code{true} on success, @code{false} on error. Possible error +returns are: + +@itemize @bullet + +@item +@code{bfd_error_no_memory} - +Not enough memory exists to create private data for @var{obfd}. +@end itemize +@example +#define bfd_set_private_flags(abfd, flags) \ + BFD_SEND (abfd, _bfd_set_private_flags, \ + (abfd, flags)) +@end example +@* +@findex stuff +@subsubsection @code{stuff} +@strong{Description}@* +Stuff which should be documented: +@example +#define bfd_sizeof_headers(abfd, reloc) \ + BFD_SEND (abfd, _bfd_sizeof_headers, (abfd, reloc)) + +#define bfd_find_nearest_line(abfd, sec, syms, off, file, func, line) \ + BFD_SEND (abfd, _bfd_find_nearest_line, (abfd, sec, syms, off, file, func, line)) + + /* Do these three do anything useful at all, for any back end? */ +#define bfd_debug_info_start(abfd) \ + BFD_SEND (abfd, _bfd_debug_info_start, (abfd)) + +#define bfd_debug_info_end(abfd) \ + BFD_SEND (abfd, _bfd_debug_info_end, (abfd)) + +#define bfd_debug_info_accumulate(abfd, section) \ + BFD_SEND (abfd, _bfd_debug_info_accumulate, (abfd, section)) + + +#define bfd_stat_arch_elt(abfd, stat) \ + BFD_SEND (abfd, _bfd_stat_arch_elt,(abfd, stat)) + +#define bfd_update_armap_timestamp(abfd) \ + BFD_SEND (abfd, _bfd_update_armap_timestamp, (abfd)) + +#define bfd_set_arch_mach(abfd, arch, mach)\ + BFD_SEND ( abfd, _bfd_set_arch_mach, (abfd, arch, mach)) + +#define bfd_relax_section(abfd, section, link_info, again) \ + BFD_SEND (abfd, _bfd_relax_section, (abfd, section, link_info, again)) + +#define bfd_link_hash_table_create(abfd) \ + BFD_SEND (abfd, _bfd_link_hash_table_create, (abfd)) + +#define bfd_link_add_symbols(abfd, info) \ + BFD_SEND (abfd, _bfd_link_add_symbols, (abfd, info)) + +#define bfd_final_link(abfd, info) \ + BFD_SEND (abfd, _bfd_final_link, (abfd, info)) + +#define bfd_free_cached_info(abfd) \ + BFD_SEND (abfd, _bfd_free_cached_info, (abfd)) + +#define bfd_get_dynamic_symtab_upper_bound(abfd) \ + BFD_SEND (abfd, _bfd_get_dynamic_symtab_upper_bound, (abfd)) + +#define bfd_print_private_bfd_data(abfd, file)\ + BFD_SEND (abfd, _bfd_print_private_bfd_data, (abfd, file)) + +#define bfd_canonicalize_dynamic_symtab(abfd, asymbols) \ + BFD_SEND (abfd, _bfd_canonicalize_dynamic_symtab, (abfd, asymbols)) + +#define bfd_get_dynamic_reloc_upper_bound(abfd) \ + BFD_SEND (abfd, _bfd_get_dynamic_reloc_upper_bound, (abfd)) + +#define bfd_canonicalize_dynamic_reloc(abfd, arels, asyms) \ + BFD_SEND (abfd, _bfd_canonicalize_dynamic_reloc, (abfd, arels, asyms)) + +extern bfd_byte *bfd_get_relocated_section_contents + PARAMS ((bfd *, struct bfd_link_info *, + struct bfd_link_order *, bfd_byte *, + boolean, asymbol **)); + +@end example +@* |