typedef bfd ¶A BFD has type 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 bfd. It
contains the major data about the file and pointers
to the rest of the data.
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;
/* The IOSTREAM, and corresponding IO vector that provide access
to the file backing the BFD. */
void *iostream;
const struct bfd_iovec *iovec;
/* The caching routines use these to maintain a
least-recently-used list of BFDs. */
struct bfd *lru_prev, *lru_next;
/* Track current file position (or current buffer offset for
in-memory BFDs). When a file is closed by the caching routines,
BFD retains state information on the file here. */
ufile_ptr where;
/* File modified time, if mtime_set is TRUE. */
long mtime;
/* A unique identifier of the BFD */
unsigned int id;
/* Format_specific flags. */
flagword flags;
/* Values that may appear in the flags field of a BFD. These also
appear in the object_flags field of the bfd_target structure, where
they indicate the set of flags used by that backend (not all flags
are meaningful for all object file formats) (FIXME: at the moment,
the object_flags values have mostly just been copied from backend
to another, and are not necessarily correct). */
#define BFD_NO_FLAGS 0x0
/* BFD contains relocation entries. */
#define HAS_RELOC 0x1
/* BFD is directly executable. */
#define EXEC_P 0x2
/* BFD has line number information (basically used for F_LNNO in a
COFF header). */
#define HAS_LINENO 0x4
/* BFD has debugging information. */
#define HAS_DEBUG 0x08
/* BFD has symbols. */
#define HAS_SYMS 0x10
/* BFD has local symbols (basically used for F_LSYMS in a COFF
header). */
#define HAS_LOCALS 0x20
/* BFD is a dynamic object. */
#define DYNAMIC 0x40
/* Text section is write protected (if D_PAGED is not set, this is
like an a.out NMAGIC file) (the linker sets this by default, but
clears it for -r or -N). */
#define WP_TEXT 0x80
/* BFD is dynamically paged (this is like an a.out ZMAGIC file) (the
linker sets this by default, but clears it for -r or -n or -N). */
#define D_PAGED 0x100
/* BFD is relaxable (this means that bfd_relax_section may be able to
do something) (sometimes bfd_relax_section can do something even if
this is not set). */
#define BFD_IS_RELAXABLE 0x200
/* This may be set before writing out a BFD to request using a
traditional format. For example, this is used to request that when
writing out an a.out object the symbols not be hashed to eliminate
duplicates. */
#define BFD_TRADITIONAL_FORMAT 0x400
/* This flag indicates that the BFD contents are actually cached
in memory. If this is set, iostream points to a malloc'd
bfd_in_memory struct. */
#define BFD_IN_MEMORY 0x800
/* This BFD has been created by the linker and doesn't correspond
to any input file. */
#define BFD_LINKER_CREATED 0x1000
/* This may be set before writing out a BFD to request that it
be written using values for UIDs, GIDs, timestamps, etc. that
will be consistent from run to run. */
#define BFD_DETERMINISTIC_OUTPUT 0x2000
/* Compress sections in this BFD. */
#define BFD_COMPRESS 0x4000
/* Decompress sections in this BFD. */
#define BFD_DECOMPRESS 0x8000
/* BFD is a dummy, for plugins. */
#define BFD_PLUGIN 0x10000
/* Compress sections in this BFD with SHF_COMPRESSED from gABI. */
#define BFD_COMPRESS_GABI 0x20000
/* Convert ELF common symbol type to STT_COMMON or STT_OBJECT in this
BFD. */
#define BFD_CONVERT_ELF_COMMON 0x40000
/* Use the ELF STT_COMMON type in this BFD. */
#define BFD_USE_ELF_STT_COMMON 0x80000
/* Put pathnames into archives (non-POSIX). */
#define BFD_ARCHIVE_FULL_PATH 0x100000
#define BFD_CLOSED_BY_CACHE 0x200000
/* Compress sections in this BFD with SHF_COMPRESSED zstd. */
#define BFD_COMPRESS_ZSTD 0x400000
/* Don't generate ELF section header. */
#define BFD_NO_SECTION_HEADER 0x800000
/* Flags bits which are for BFD use only. */
#define BFD_FLAGS_FOR_BFD_USE_MASK \
(BFD_IN_MEMORY | BFD_COMPRESS | BFD_DECOMPRESS | BFD_LINKER_CREATED \
| BFD_PLUGIN | BFD_TRADITIONAL_FORMAT | BFD_DETERMINISTIC_OUTPUT \
| BFD_COMPRESS_GABI | BFD_CONVERT_ELF_COMMON | BFD_USE_ELF_STT_COMMON \
| BFD_NO_SECTION_HEADER)
/* The format which belongs to the BFD. (object, core, etc.) */
ENUM_BITFIELD (bfd_format) format : 3;
/* The direction with which the BFD was opened. */
ENUM_BITFIELD (bfd_direction) direction : 2;
/* POSIX.1-2017 (IEEE Std 1003.1) says of fopen : "When a file is
opened with update mode ('+' as the second or third character in
the mode argument), both input and output may be performed on
the associated stream. However, the application shall ensure
that output is not directly followed by input without an
intervening call to fflush() or to a file positioning function
(fseek(), fsetpos(), or rewind()), and input is not directly
followed by output without an intervening call to a file
positioning function, unless the input operation encounters
end-of-file."
This field tracks the last IO operation, so that bfd can insert
a seek when IO direction changes. */
ENUM_BITFIELD (bfd_last_io) last_io : 2;
/* Is the file descriptor being cached? That is, can it be closed as
needed, and re-opened when accessed later? */
unsigned int cacheable : 1;
/* 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. */
unsigned int target_defaulted : 1;
/* ... and here: (``once'' means at least once). */
unsigned int opened_once : 1;
/* Set if we have a locally maintained mtime value, rather than
getting it from the file each time. */
unsigned int mtime_set : 1;
/* Flag set if symbols from this BFD should not be exported. */
unsigned int no_export : 1;
/* Remember when output has begun, to stop strange things
from happening. */
unsigned int output_has_begun : 1;
/* Have archive map. */
unsigned int has_armap : 1;
/* Accept a mapless archive for link. */
unsigned int link_mapless : 1;
/* Set if this is a thin archive. */
unsigned int is_thin_archive : 1;
/* Set if this is a collection of files pretending to be an archive. */
unsigned int is_fake_archive : 1;
/* Set if this archive should not cache element positions. */
unsigned int no_element_cache : 1;
/* Set if only required symbols should be added in the link hash table for
this object. Used by VMS linkers. */
unsigned int selective_search : 1;
/* Set if this is the linker output BFD. */
unsigned int is_linker_output : 1;
/* Set if this is the linker input BFD. */
unsigned int is_linker_input : 1;
/* If this is an input for a compiler plug-in library. */
ENUM_BITFIELD (bfd_plugin_format) plugin_format : 2;
/* Set if this is a plugin output file. */
unsigned int lto_output : 1;
/* Do not attempt to modify this file. Set when detecting errors
that BFD is not prepared to handle for objcopy/strip. */
unsigned int read_only : 1;
/* LTO object type. */
ENUM_BITFIELD (bfd_lto_object_type) lto_type : 3;
/* Set if this BFD is currently being processed by
bfd_check_format_matches. This is checked by the cache to
avoid closing the BFD in this case. This should only be
examined or modified while the BFD lock is held. */
unsigned int in_format_matches : 1;
/* Set to dummy BFD created when claimed by a compiler plug-in
library. */
bfd *plugin_dummy_bfd;
/* The offset of this bfd in the file, typically 0 if it is not
contained in an archive. */
ufile_ptr origin;
/* A reference in the archive for the proxy entry as follows:
1. For regular archives this will be the same as origin.
2. For thin archives it will contain the current offset
of the proxy in the thin archive rather than the offset
of the bfd in its actual container.
3. For fake archives it will contain the next archive member's
BFD reference or a NULL pointer if this is the last member. */
ufile_ptr_or_bfd proxy_handle;
/* A hash table for section names. */
struct bfd_hash_table section_htab;
/* Pointer to linked list of sections. */
struct bfd_section *sections;
/* The last section on the section list. */
struct bfd_section *section_last;
/* The object-only section on the section list. */
struct bfd_section *object_only_section;
/* The number of sections. */
unsigned int section_count;
/* The archive plugin file descriptor. */
int archive_plugin_fd;
/* The number of opens on the archive plugin file descriptor. */
unsigned int archive_plugin_fd_open_count;
/* A field used by _bfd_generic_link_add_archive_symbols. This will
be used only for archive elements. */
int archive_pass;
/* The total size of memory from bfd_alloc. */
bfd_size_type alloc_size;
/* Stuff only useful for object files:
The start address. */
bfd_vma start_address;
/* Symbol table for output BFD (with symcount entries).
Also used by the linker to cache input BFD symbols. */
struct bfd_symbol **outsymbols;
/* Used for input and output. */
unsigned int symcount;
/* Used for slurped dynamic symbol tables. */
unsigned int dynsymcount;
/* Pointer to structure which contains architecture information. */
const struct bfd_arch_info *arch_info;
/* Cached length of file for bfd_get_size. 0 until bfd_get_size is
called, 1 if stat returns an error or the file size is too large to
return in ufile_ptr. Both 0 and 1 should be treated as "unknown". */
ufile_ptr size;
/* Stuff only useful for archives. */
void *arelt_data;
struct bfd *my_archive; /* The containing archive BFD. */
struct bfd *archive_next; /* The next BFD in the archive. */
struct bfd *archive_head; /* The first BFD in the archive. */
struct bfd *nested_archives; /* List of nested archive in a flattened
thin archive. */
union {
/* For input BFDs, a chain of BFDs involved in a link. */
struct bfd *next;
/* For output BFD, the linker hash table. */
struct bfd_link_hash_table *hash;
} link;
/* Used by the back end to hold private data. */
union
{
struct aout_data_struct *aout_data;
struct artdata *aout_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 srec_data_struct *srec_data;
struct verilog_data_struct *verilog_data;
struct ihex_data_struct *ihex_data;
struct tekhex_data_struct *tekhex_data;
struct elf_obj_tdata *elf_obj_data;
struct mmo_data_struct *mmo_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 netbsd_core_struct *netbsd_core_data;
struct mach_o_data_struct *mach_o_data;
struct mach_o_fat_data_struct *mach_o_fat_data;
struct plugin_data_struct *plugin_data;
struct bfd_pef_data_struct *pef_data;
struct bfd_pef_xlib_data_struct *pef_xlib_data;
struct bfd_sym_data_struct *sym_data;
void *any;
}
tdata;
/* Used by the application to hold private data. */
void *usrdata;
/* Where all the allocated stuff under this BFD goes. This is a
struct objalloc *, but we use void * to avoid requiring the inclusion
of objalloc.h. */
void *memory;
/* For input BFDs, the build ID, if the object has one. */
const struct bfd_build_id *build_id;
/* For input BFDs, mmapped entries. */
struct bfd_mmapped *mmapped;
};