1 /* Object file "section" support for the BFD library.
2 Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
4 Free Software Foundation, Inc.
5 Written by Cygnus Support.
7 This file is part of BFD, the Binary File Descriptor library.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
27 The raw data contained within a BFD is maintained through the
28 section abstraction. A single BFD may have any number of
29 sections. It keeps hold of them by pointing to the first;
30 each one points to the next in the list.
32 Sections are supported in BFD in <<section.c>>.
38 @* section prototypes::
42 Section Input, Section Output, Sections, Sections
46 When a BFD is opened for reading, the section structures are
47 created and attached to the BFD.
49 Each section has a name which describes the section in the
50 outside world---for example, <<a.out>> would contain at least
51 three sections, called <<.text>>, <<.data>> and <<.bss>>.
53 Names need not be unique; for example a COFF file may have several
54 sections named <<.data>>.
56 Sometimes a BFD will contain more than the ``natural'' number of
57 sections. A back end may attach other sections containing
58 constructor data, or an application may add a section (using
59 <<bfd_make_section>>) to the sections attached to an already open
60 BFD. For example, the linker creates an extra section
61 <<COMMON>> for each input file's BFD to hold information about
64 The raw data is not necessarily read in when
65 the section descriptor is created. Some targets may leave the
66 data in place until a <<bfd_get_section_contents>> call is
67 made. Other back ends may read in all the data at once. For
68 example, an S-record file has to be read once to determine the
69 size of the data. An IEEE-695 file doesn't contain raw data in
70 sections, but data and relocation expressions intermixed, so
71 the data area has to be parsed to get out the data and
75 Section Output, typedef asection, Section Input, Sections
80 To write a new object style BFD, the various sections to be
81 written have to be created. They are attached to the BFD in
82 the same way as input sections; data is written to the
83 sections using <<bfd_set_section_contents>>.
85 Any program that creates or combines sections (e.g., the assembler
86 and linker) must use the <<asection>> fields <<output_section>> and
87 <<output_offset>> to indicate the file sections to which each
88 section must be written. (If the section is being created from
89 scratch, <<output_section>> should probably point to the section
90 itself and <<output_offset>> should probably be zero.)
92 The data to be written comes from input sections attached
93 (via <<output_section>> pointers) to
94 the output sections. The output section structure can be
95 considered a filter for the input section: the output section
96 determines the vma of the output data and the name, but the
97 input section determines the offset into the output section of
98 the data to be written.
100 E.g., to create a section "O", starting at 0x100, 0x123 long,
101 containing two subsections, "A" at offset 0x0 (i.e., at vma
102 0x100) and "B" at offset 0x20 (i.e., at vma 0x120) the <<asection>>
103 structures would look like:
108 | output_section -----------> section name "O"
110 | section name "B" | size 0x123
111 | output_offset 0x20 |
113 | output_section --------|
118 The data within a section is stored in a @dfn{link_order}.
119 These are much like the fixups in <<gas>>. The link_order
120 abstraction allows a section to grow and shrink within itself.
122 A link_order knows how big it is, and which is the next
123 link_order and where the raw data for it is; it also points to
124 a list of relocations which apply to it.
126 The link_order is used by the linker to perform relaxing on
127 final code. The compiler creates code which is as big as
128 necessary to make it work without relaxing, and the user can
129 select whether to relax. Sometimes relaxing takes a lot of
130 time. The linker runs around the relocations to see if any
131 are attached to data which can be shrunk, if so it does it on
132 a link_order by link_order basis.
144 typedef asection, section prototypes, Section Output, Sections
148 Here is the section structure:
152 .{* This structure is used for a comdat section, as in PE. A comdat
153 . section is associated with a particular symbol. When the linker
154 . sees a comdat section, it keeps only one of the sections with a
155 . given name and associated with a given symbol. *}
157 .struct bfd_comdat_info
159 . {* The name of the symbol associated with a comdat section. *}
162 . {* The local symbol table index of the symbol associated with a
163 . comdat section. This is only meaningful to the object file format
164 . specific code; it is not an index into the list returned by
165 . bfd_canonicalize_symtab. *}
171 . {* The name of the section; the name isn't a copy, the pointer is
172 . the same as that passed to bfd_make_section. *}
175 . {* A unique sequence number. *}
178 . {* Which section in the bfd; 0..n-1 as sections are created in a bfd. *}
181 . {* The next section in the list belonging to the BFD, or NULL. *}
184 . {* The field flags contains attributes of the section. Some
185 . flags are read in from the object file, and some are
186 . synthesized from other information. *}
189 .#define SEC_NO_FLAGS 0x000
191 . {* Tells the OS to allocate space for this section when loading.
192 . This is clear for a section containing debug information only. *}
193 .#define SEC_ALLOC 0x001
195 . {* Tells the OS to load the section from the file when loading.
196 . This is clear for a .bss section. *}
197 .#define SEC_LOAD 0x002
199 . {* The section contains data still to be relocated, so there is
200 . some relocation information too. *}
201 .#define SEC_RELOC 0x004
203 . {* ELF reserves 4 processor specific bits and 8 operating system
204 . specific bits in sh_flags; at present we can get away with just
205 . one in communicating between the assembler and BFD, but this
206 . isn't a good long-term solution. *}
207 .#define SEC_ARCH_BIT_0 0x008
209 . {* A signal to the OS that the section contains read only data. *}
210 .#define SEC_READONLY 0x010
212 . {* The section contains code only. *}
213 .#define SEC_CODE 0x020
215 . {* The section contains data only. *}
216 .#define SEC_DATA 0x040
218 . {* The section will reside in ROM. *}
219 .#define SEC_ROM 0x080
221 . {* The section contains constructor information. This section
222 . type is used by the linker to create lists of constructors and
223 . destructors used by <<g++>>. When a back end sees a symbol
224 . which should be used in a constructor list, it creates a new
225 . section for the type of name (e.g., <<__CTOR_LIST__>>), attaches
226 . the symbol to it, and builds a relocation. To build the lists
227 . of constructors, all the linker has to do is catenate all the
228 . sections called <<__CTOR_LIST__>> and relocate the data
229 . contained within - exactly the operations it would peform on
231 .#define SEC_CONSTRUCTOR 0x100
233 . {* The section has contents - a data section could be
234 . <<SEC_ALLOC>> | <<SEC_HAS_CONTENTS>>; a debug section could be
235 . <<SEC_HAS_CONTENTS>> *}
236 .#define SEC_HAS_CONTENTS 0x200
238 . {* An instruction to the linker to not output the section
239 . even if it has information which would normally be written. *}
240 .#define SEC_NEVER_LOAD 0x400
242 . {* The section is a COFF shared library section. This flag is
243 . only for the linker. If this type of section appears in
244 . the input file, the linker must copy it to the output file
245 . without changing the vma or size. FIXME: Although this
246 . was originally intended to be general, it really is COFF
247 . specific (and the flag was renamed to indicate this). It
248 . might be cleaner to have some more general mechanism to
249 . allow the back end to control what the linker does with
251 .#define SEC_COFF_SHARED_LIBRARY 0x800
253 . {* The section contains thread local data. *}
254 .#define SEC_THREAD_LOCAL 0x1000
256 . {* The section has GOT references. This flag is only for the
257 . linker, and is currently only used by the elf32-hppa back end.
258 . It will be set if global offset table references were detected
259 . in this section, which indicate to the linker that the section
260 . contains PIC code, and must be handled specially when doing a
262 .#define SEC_HAS_GOT_REF 0x4000
264 . {* The section contains common symbols (symbols may be defined
265 . multiple times, the value of a symbol is the amount of
266 . space it requires, and the largest symbol value is the one
267 . used). Most targets have exactly one of these (which we
268 . translate to bfd_com_section_ptr), but ECOFF has two. *}
269 .#define SEC_IS_COMMON 0x8000
271 . {* The section contains only debugging information. For
272 . example, this is set for ELF .debug and .stab sections.
273 . strip tests this flag to see if a section can be
275 .#define SEC_DEBUGGING 0x10000
277 . {* The contents of this section are held in memory pointed to
278 . by the contents field. This is checked by bfd_get_section_contents,
279 . and the data is retrieved from memory if appropriate. *}
280 .#define SEC_IN_MEMORY 0x20000
282 . {* The contents of this section are to be excluded by the
283 . linker for executable and shared objects unless those
284 . objects are to be further relocated. *}
285 .#define SEC_EXCLUDE 0x40000
287 . {* The contents of this section are to be sorted based on the sum of
288 . the symbol and addend values specified by the associated relocation
289 . entries. Entries without associated relocation entries will be
290 . appended to the end of the section in an unspecified order. *}
291 .#define SEC_SORT_ENTRIES 0x80000
293 . {* When linking, duplicate sections of the same name should be
294 . discarded, rather than being combined into a single section as
295 . is usually done. This is similar to how common symbols are
296 . handled. See SEC_LINK_DUPLICATES below. *}
297 .#define SEC_LINK_ONCE 0x100000
299 . {* If SEC_LINK_ONCE is set, this bitfield describes how the linker
300 . should handle duplicate sections. *}
301 .#define SEC_LINK_DUPLICATES 0x600000
303 . {* This value for SEC_LINK_DUPLICATES means that duplicate
304 . sections with the same name should simply be discarded. *}
305 .#define SEC_LINK_DUPLICATES_DISCARD 0x0
307 . {* This value for SEC_LINK_DUPLICATES means that the linker
308 . should warn if there are any duplicate sections, although
309 . it should still only link one copy. *}
310 .#define SEC_LINK_DUPLICATES_ONE_ONLY 0x200000
312 . {* This value for SEC_LINK_DUPLICATES means that the linker
313 . should warn if any duplicate sections are a different size. *}
314 .#define SEC_LINK_DUPLICATES_SAME_SIZE 0x400000
316 . {* This value for SEC_LINK_DUPLICATES means that the linker
317 . should warn if any duplicate sections contain different
319 .#define SEC_LINK_DUPLICATES_SAME_CONTENTS 0x600000
321 . {* This section was created by the linker as part of dynamic
322 . relocation or other arcane processing. It is skipped when
323 . going through the first-pass output, trusting that someone
324 . else up the line will take care of it later. *}
325 .#define SEC_LINKER_CREATED 0x800000
327 . {* This section should not be subject to garbage collection. *}
328 .#define SEC_KEEP 0x1000000
330 . {* This section contains "short" data, and should be placed
332 .#define SEC_SMALL_DATA 0x2000000
334 . {* This section contains data which may be shared with other
335 . executables or shared objects. *}
336 .#define SEC_SHARED 0x4000000
338 . {* When a section with this flag is being linked, then if the size of
339 . the input section is less than a page, it should not cross a page
340 . boundary. If the size of the input section is one page or more, it
341 . should be aligned on a page boundary. *}
342 .#define SEC_BLOCK 0x8000000
344 . {* Conditionally link this section; do not link if there are no
345 . references found to any symbol in the section. *}
346 .#define SEC_CLINK 0x10000000
348 . {* Attempt to merge identical entities in the section.
349 . Entity size is given in the entsize field. *}
350 .#define SEC_MERGE 0x20000000
352 . {* If given with SEC_MERGE, entities to merge are zero terminated
353 . strings where entsize specifies character size instead of fixed
355 .#define SEC_STRINGS 0x40000000
357 . {* This section contains data about section groups. *}
358 .#define SEC_GROUP 0x80000000
360 . {* End of section flags. *}
362 . {* Some internal packed boolean fields. *}
364 . {* See the vma field. *}
365 . unsigned int user_set_vma : 1;
367 . {* Whether relocations have been processed. *}
368 . unsigned int reloc_done : 1;
370 . {* A mark flag used by some of the linker backends. *}
371 . unsigned int linker_mark : 1;
373 . {* Another mark flag used by some of the linker backends. Set for
374 . output sections that have an input section. *}
375 . unsigned int linker_has_input : 1;
377 . {* A mark flag used by some linker backends for garbage collection. *}
378 . unsigned int gc_mark : 1;
380 . {* The following flags are used by the ELF linker. *}
382 . {* Mark sections which have been allocated to segments. *}
383 . unsigned int segment_mark : 1;
385 . {* Type of sec_info information. *}
386 . unsigned int sec_info_type:3;
387 .#define ELF_INFO_TYPE_NONE 0
388 .#define ELF_INFO_TYPE_STABS 1
389 .#define ELF_INFO_TYPE_MERGE 2
390 .#define ELF_INFO_TYPE_EH_FRAME 3
391 .#define ELF_INFO_TYPE_JUST_SYMS 4
393 . {* Nonzero if this section uses RELA relocations, rather than REL. *}
394 . unsigned int use_rela_p:1;
396 . {* Bits used by various backends. *}
397 . unsigned int has_tls_reloc:1;
400 . unsigned int flag11:1;
401 . unsigned int flag12:1;
402 . unsigned int flag13:1;
403 . unsigned int flag14:1;
404 . unsigned int flag15:1;
405 . unsigned int flag16:4;
406 . unsigned int flag20:4;
407 . unsigned int flag24:8;
409 . {* End of internal packed boolean fields. *}
411 . {* The virtual memory address of the section - where it will be
412 . at run time. The symbols are relocated against this. The
413 . user_set_vma flag is maintained by bfd; if it's not set, the
414 . backend can assign addresses (for example, in <<a.out>>, where
415 . the default address for <<.data>> is dependent on the specific
416 . target and various flags). *}
419 . {* The load address of the section - where it would be in a
420 . rom image; really only used for writing section header
424 . {* The size of the section in octets, as it will be output.
425 . Contains a value even if the section has no contents (e.g., the
426 . size of <<.bss>>). This will be filled in after relocation. *}
427 . bfd_size_type _cooked_size;
429 . {* The original size on disk of the section, in octets. Normally this
430 . value is the same as the size, but if some relaxing has
431 . been done, then this value will be bigger. *}
432 . bfd_size_type _raw_size;
434 . {* If this section is going to be output, then this value is the
435 . offset in *bytes* into the output section of the first byte in the
436 . input section (byte ==> smallest addressable unit on the
437 . target). In most cases, if this was going to start at the
438 . 100th octet (8-bit quantity) in the output section, this value
439 . would be 100. However, if the target byte size is 16 bits
440 . (bfd_octets_per_byte is "2"), this value would be 50. *}
441 . bfd_vma output_offset;
443 . {* The output section through which to map on output. *}
444 . struct sec *output_section;
446 . {* The alignment requirement of the section, as an exponent of 2 -
447 . e.g., 3 aligns to 2^3 (or 8). *}
448 . unsigned int alignment_power;
450 . {* If an input section, a pointer to a vector of relocation
451 . records for the data in this section. *}
452 . struct reloc_cache_entry *relocation;
454 . {* If an output section, a pointer to a vector of pointers to
455 . relocation records for the data in this section. *}
456 . struct reloc_cache_entry **orelocation;
458 . {* The number of relocation records in one of the above. *}
459 . unsigned reloc_count;
461 . {* Information below is back end specific - and not always used
464 . {* File position of section data. *}
467 . {* File position of relocation info. *}
468 . file_ptr rel_filepos;
470 . {* File position of line data. *}
471 . file_ptr line_filepos;
473 . {* Pointer to data for applications. *}
476 . {* If the SEC_IN_MEMORY flag is set, this points to the actual
478 . unsigned char *contents;
480 . {* Attached line number information. *}
483 . {* Number of line number records. *}
484 . unsigned int lineno_count;
486 . {* Entity size for merging purposes. *}
487 . unsigned int entsize;
489 . {* Optional information about a COMDAT entry; NULL if not COMDAT. *}
490 . struct bfd_comdat_info *comdat;
492 . {* When a section is being output, this value changes as more
493 . linenumbers are written out. *}
494 . file_ptr moving_line_filepos;
496 . {* What the section number is in the target world. *}
501 . {* If this is a constructor section then here is a list of the
502 . relocations created to relocate items within it. *}
503 . struct relent_chain *constructor_chain;
505 . {* The BFD which owns the section. *}
508 . {* A symbol which points at this section only. *}
509 . struct symbol_cache_entry *symbol;
510 . struct symbol_cache_entry **symbol_ptr_ptr;
512 . struct bfd_link_order *link_order_head;
513 . struct bfd_link_order *link_order_tail;
516 .{* These sections are global, and are managed by BFD. The application
517 . and target back end are not permitted to change the values in
518 . these sections. New code should use the section_ptr macros rather
519 . than referring directly to the const sections. The const sections
520 . may eventually vanish. *}
521 .#define BFD_ABS_SECTION_NAME "*ABS*"
522 .#define BFD_UND_SECTION_NAME "*UND*"
523 .#define BFD_COM_SECTION_NAME "*COM*"
524 .#define BFD_IND_SECTION_NAME "*IND*"
526 .{* The absolute section. *}
527 .extern const asection bfd_abs_section;
528 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
529 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
530 .{* Pointer to the undefined section. *}
531 .extern const asection bfd_und_section;
532 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
533 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
534 .{* Pointer to the common section. *}
535 .extern const asection bfd_com_section;
536 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
537 .{* Pointer to the indirect section. *}
538 .extern const asection bfd_ind_section;
539 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
540 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
542 .#define bfd_is_const_section(SEC) \
543 . ( ((SEC) == bfd_abs_section_ptr) \
544 . || ((SEC) == bfd_und_section_ptr) \
545 . || ((SEC) == bfd_com_section_ptr) \
546 . || ((SEC) == bfd_ind_section_ptr))
548 .extern const struct symbol_cache_entry * const bfd_abs_symbol;
549 .extern const struct symbol_cache_entry * const bfd_com_symbol;
550 .extern const struct symbol_cache_entry * const bfd_und_symbol;
551 .extern const struct symbol_cache_entry * const bfd_ind_symbol;
552 .#define bfd_get_section_size_before_reloc(section) \
553 . ((section)->reloc_done ? (abort (), (bfd_size_type) 1) \
554 . : (section)->_raw_size)
555 .#define bfd_get_section_size_after_reloc(section) \
556 . ((section)->reloc_done ? (section)->_cooked_size \
557 . : (abort (), (bfd_size_type) 1))
559 .{* Macros to handle insertion and deletion of a bfd's sections. These
560 . only handle the list pointers, ie. do not adjust section_count,
561 . target_index etc. *}
562 .#define bfd_section_list_remove(ABFD, PS) \
565 . asection **_ps = PS; \
566 . asection *_s = *_ps; \
568 . if (_s->next == NULL) \
569 . (ABFD)->section_tail = _ps; \
572 .#define bfd_section_list_insert(ABFD, PS, S) \
575 . asection **_ps = PS; \
576 . asection *_s = S; \
579 . if (_s->next == NULL) \
580 . (ABFD)->section_tail = &_s->next; \
586 /* We use a macro to initialize the static asymbol structures because
587 traditional C does not permit us to initialize a union member while
588 gcc warns if we don't initialize it. */
589 /* the_bfd, name, value, attr, section [, udata] */
591 #define GLOBAL_SYM_INIT(NAME, SECTION) \
592 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION, { 0 }}
594 #define GLOBAL_SYM_INIT(NAME, SECTION) \
595 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION }
598 /* These symbols are global, not specific to any BFD. Therefore, anything
599 that tries to change them is broken, and should be repaired. */
601 static const asymbol global_syms[] =
603 GLOBAL_SYM_INIT (BFD_COM_SECTION_NAME, &bfd_com_section),
604 GLOBAL_SYM_INIT (BFD_UND_SECTION_NAME, &bfd_und_section),
605 GLOBAL_SYM_INIT (BFD_ABS_SECTION_NAME, &bfd_abs_section),
606 GLOBAL_SYM_INIT (BFD_IND_SECTION_NAME, &bfd_ind_section)
609 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
610 const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
611 const asection SEC = \
612 /* name, id, index, next, flags, user_set_vma, reloc_done, */ \
613 { NAME, IDX, 0, NULL, FLAGS, 0, 0, \
615 /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \
618 /* sec_info_type, use_rela_p, has_tls_reloc, flag11, flag12, */ \
621 /* flag13, flag14, flag15, flag16, flag20, flag24, */ \
624 /* vma, lma, _cooked_size, _raw_size, */ \
627 /* output_offset, output_section, alignment_power, */ \
628 0, (struct sec *) &SEC, 0, \
630 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
631 NULL, NULL, 0, 0, 0, \
633 /* line_filepos, userdata, contents, lineno, lineno_count, */ \
634 0, NULL, NULL, NULL, 0, \
636 /* entsize, comdat, moving_line_filepos, */ \
639 /* target_index, used_by_bfd, constructor_chain, owner, */ \
640 0, NULL, NULL, NULL, \
643 (struct symbol_cache_entry *) &global_syms[IDX], \
645 /* symbol_ptr_ptr, */ \
646 (struct symbol_cache_entry **) &SYM, \
648 /* link_order_head, link_order_tail */ \
652 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
653 BFD_COM_SECTION_NAME, 0);
654 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
655 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
656 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
659 struct section_hash_entry
661 struct bfd_hash_entry root;
665 /* Initialize an entry in the section hash table. */
667 struct bfd_hash_entry *
668 bfd_section_hash_newfunc (entry, table, string)
669 struct bfd_hash_entry *entry;
670 struct bfd_hash_table *table;
673 /* Allocate the structure if it has not already been allocated by a
677 entry = (struct bfd_hash_entry *)
678 bfd_hash_allocate (table, sizeof (struct section_hash_entry));
683 /* Call the allocation method of the superclass. */
684 entry = bfd_hash_newfunc (entry, table, string);
687 memset ((PTR) &((struct section_hash_entry *) entry)->section,
688 0, sizeof (asection));
694 #define section_hash_lookup(table, string, create, copy) \
695 ((struct section_hash_entry *) \
696 bfd_hash_lookup ((table), (string), (create), (copy)))
698 /* Initializes a new section. NEWSECT->NAME is already set. */
700 static asection *bfd_section_init PARAMS ((bfd *, asection *));
703 bfd_section_init (abfd, newsect)
707 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */
709 newsect->id = section_id;
710 newsect->index = abfd->section_count;
711 newsect->owner = abfd;
713 /* Create a symbol whose only job is to point to this section. This
714 is useful for things like relocs which are relative to the base
716 newsect->symbol = bfd_make_empty_symbol (abfd);
717 if (newsect->symbol == NULL)
720 newsect->symbol->name = newsect->name;
721 newsect->symbol->value = 0;
722 newsect->symbol->section = newsect;
723 newsect->symbol->flags = BSF_SECTION_SYM;
725 newsect->symbol_ptr_ptr = &newsect->symbol;
727 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect)))
731 abfd->section_count++;
732 *abfd->section_tail = newsect;
733 abfd->section_tail = &newsect->next;
740 section prototypes, , typedef asection, Sections
744 These are the functions exported by the section handling part of BFD.
749 bfd_section_list_clear
752 void bfd_section_list_clear (bfd *);
755 Clears the section list, and also resets the section count and
760 bfd_section_list_clear (abfd)
763 abfd->sections = NULL;
764 abfd->section_tail = &abfd->sections;
765 abfd->section_count = 0;
766 memset ((PTR) abfd->section_htab.table, 0,
767 abfd->section_htab.size * sizeof (struct bfd_hash_entry *));
772 bfd_get_section_by_name
775 asection *bfd_get_section_by_name(bfd *abfd, const char *name);
778 Run through @var{abfd} and return the one of the
779 <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
780 @xref{Sections}, for more information.
782 This should only be used in special cases; the normal way to process
783 all sections of a given name is to use <<bfd_map_over_sections>> and
784 <<strcmp>> on the name (or better yet, base it on the section flags
785 or something else) for each section.
789 bfd_get_section_by_name (abfd, name)
793 struct section_hash_entry *sh;
795 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
804 bfd_get_unique_section_name
807 char *bfd_get_unique_section_name(bfd *abfd,
812 Invent a section name that is unique in @var{abfd} by tacking
813 a dot and a digit suffix onto the original @var{templat}. If
814 @var{count} is non-NULL, then it specifies the first number
815 tried as a suffix to generate a unique name. The value
816 pointed to by @var{count} will be incremented in this case.
820 bfd_get_unique_section_name (abfd, templat, count)
829 len = strlen (templat);
830 sname = bfd_malloc ((bfd_size_type) len + 8);
833 memcpy (sname, templat, len);
840 /* If we have a million sections, something is badly wrong. */
843 sprintf (sname + len, ".%d", num++);
845 while (section_hash_lookup (&abfd->section_htab, sname, FALSE, FALSE));
854 bfd_make_section_old_way
857 asection *bfd_make_section_old_way(bfd *abfd, const char *name);
860 Create a new empty section called @var{name}
861 and attach it to the end of the chain of sections for the
862 BFD @var{abfd}. An attempt to create a section with a name which
863 is already in use returns its pointer without changing the
866 It has the funny name since this is the way it used to be
867 before it was rewritten....
870 o <<bfd_error_invalid_operation>> -
871 If output has already started for this BFD.
872 o <<bfd_error_no_memory>> -
873 If memory allocation fails.
878 bfd_make_section_old_way (abfd, name)
882 struct section_hash_entry *sh;
885 if (abfd->output_has_begun)
887 bfd_set_error (bfd_error_invalid_operation);
891 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
892 return bfd_abs_section_ptr;
894 if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
895 return bfd_com_section_ptr;
897 if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
898 return bfd_und_section_ptr;
900 if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
901 return bfd_ind_section_ptr;
903 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
907 newsect = &sh->section;
908 if (newsect->name != NULL)
910 /* Section already exists. */
914 newsect->name = name;
915 return bfd_section_init (abfd, newsect);
920 bfd_make_section_anyway
923 asection *bfd_make_section_anyway(bfd *abfd, const char *name);
926 Create a new empty section called @var{name} and attach it to the end of
927 the chain of sections for @var{abfd}. Create a new section even if there
928 is already a section with that name.
930 Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
931 o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
932 o <<bfd_error_no_memory>> - If memory allocation fails.
936 bfd_make_section_anyway (abfd, name)
940 struct section_hash_entry *sh;
943 if (abfd->output_has_begun)
945 bfd_set_error (bfd_error_invalid_operation);
949 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
953 newsect = &sh->section;
954 if (newsect->name != NULL)
956 /* We are making a section of the same name. It can't go in
957 section_htab without generating a unique section name and
958 that would be pointless; We don't need to traverse the
960 newsect = (asection *) bfd_zalloc (abfd, sizeof (asection));
965 newsect->name = name;
966 return bfd_section_init (abfd, newsect);
974 asection *bfd_make_section(bfd *, const char *name);
977 Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
978 bfd_set_error ()) without changing the section chain if there is already a
979 section named @var{name}. If there is an error, return <<NULL>> and set
984 bfd_make_section (abfd, name)
988 struct section_hash_entry *sh;
991 if (abfd->output_has_begun)
993 bfd_set_error (bfd_error_invalid_operation);
997 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0
998 || strcmp (name, BFD_COM_SECTION_NAME) == 0
999 || strcmp (name, BFD_UND_SECTION_NAME) == 0
1000 || strcmp (name, BFD_IND_SECTION_NAME) == 0)
1003 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
1007 newsect = &sh->section;
1008 if (newsect->name != NULL)
1010 /* Section already exists. */
1014 newsect->name = name;
1015 return bfd_section_init (abfd, newsect);
1020 bfd_set_section_flags
1023 bfd_boolean bfd_set_section_flags (bfd *abfd, asection *sec, flagword flags);
1026 Set the attributes of the section @var{sec} in the BFD
1027 @var{abfd} to the value @var{flags}. Return <<TRUE>> on success,
1028 <<FALSE>> on error. Possible error returns are:
1030 o <<bfd_error_invalid_operation>> -
1031 The section cannot have one or more of the attributes
1032 requested. For example, a .bss section in <<a.out>> may not
1033 have the <<SEC_HAS_CONTENTS>> field set.
1039 bfd_set_section_flags (abfd, section, flags)
1040 bfd *abfd ATTRIBUTE_UNUSED;
1045 /* If you try to copy a text section from an input file (where it
1046 has the SEC_CODE flag set) to an output file, this loses big if
1047 the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
1048 set - which it doesn't, at least not for a.out. FIXME */
1050 if ((flags & bfd_applicable_section_flags (abfd)) != flags)
1052 bfd_set_error (bfd_error_invalid_operation);
1057 section->flags = flags;
1063 bfd_map_over_sections
1066 void bfd_map_over_sections(bfd *abfd,
1067 void (*func) (bfd *abfd,
1073 Call the provided function @var{func} for each section
1074 attached to the BFD @var{abfd}, passing @var{obj} as an
1075 argument. The function will be called as if by
1077 | func(abfd, the_section, obj);
1079 This is the prefered method for iterating over sections; an
1080 alternative would be to use a loop:
1083 | for (p = abfd->sections; p != NULL; p = p->next)
1084 | func(abfd, p, ...)
1090 bfd_map_over_sections (abfd, operation, user_storage)
1092 void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj));
1098 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
1099 (*operation) (abfd, sect, user_storage);
1101 if (i != abfd->section_count) /* Debugging */
1107 bfd_set_section_size
1110 bfd_boolean bfd_set_section_size (bfd *abfd, asection *sec, bfd_size_type val);
1113 Set @var{sec} to the size @var{val}. If the operation is
1114 ok, then <<TRUE>> is returned, else <<FALSE>>.
1116 Possible error returns:
1117 o <<bfd_error_invalid_operation>> -
1118 Writing has started to the BFD, so setting the size is invalid.
1123 bfd_set_section_size (abfd, ptr, val)
1128 /* Once you've started writing to any section you cannot create or change
1129 the size of any others. */
1131 if (abfd->output_has_begun)
1133 bfd_set_error (bfd_error_invalid_operation);
1137 ptr->_cooked_size = val;
1138 ptr->_raw_size = val;
1145 bfd_set_section_contents
1148 bfd_boolean bfd_set_section_contents (bfd *abfd, asection *section,
1149 PTR data, file_ptr offset,
1150 bfd_size_type count);
1153 Sets the contents of the section @var{section} in BFD
1154 @var{abfd} to the data starting in memory at @var{data}. The
1155 data is written to the output section starting at offset
1156 @var{offset} for @var{count} octets.
1158 Normally <<TRUE>> is returned, else <<FALSE>>. Possible error
1160 o <<bfd_error_no_contents>> -
1161 The output section does not have the <<SEC_HAS_CONTENTS>>
1162 attribute, so nothing can be written to it.
1165 This routine is front end to the back end function
1166 <<_bfd_set_section_contents>>.
1170 #define bfd_get_section_size_now(abfd,sec) \
1172 ? bfd_get_section_size_after_reloc (sec) \
1173 : bfd_get_section_size_before_reloc (sec))
1176 bfd_set_section_contents (abfd, section, location, offset, count)
1181 bfd_size_type count;
1185 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
1187 bfd_set_error (bfd_error_no_contents);
1191 sz = bfd_get_section_size_now (abfd, section);
1192 if ((bfd_size_type) offset > sz
1194 || offset + count > sz
1195 || count != (size_t) count)
1197 bfd_set_error (bfd_error_bad_value);
1201 switch (abfd->direction)
1203 case read_direction:
1205 bfd_set_error (bfd_error_invalid_operation);
1208 case write_direction:
1211 case both_direction:
1212 /* File is opened for update. `output_has_begun' some time ago when
1213 the file was created. Do not recompute sections sizes or alignments
1214 in _bfd_set_section_content. */
1215 abfd->output_has_begun = TRUE;
1219 /* Record a copy of the data in memory if desired. */
1220 if (section->contents
1221 && location != (PTR) (section->contents + offset))
1222 memcpy (section->contents + offset, location, (size_t) count);
1224 if (BFD_SEND (abfd, _bfd_set_section_contents,
1225 (abfd, section, location, offset, count)))
1227 abfd->output_has_begun = TRUE;
1236 bfd_get_section_contents
1239 bfd_boolean bfd_get_section_contents (bfd *abfd, asection *section,
1240 PTR location, file_ptr offset,
1241 bfd_size_type count);
1244 Read data from @var{section} in BFD @var{abfd}
1245 into memory starting at @var{location}. The data is read at an
1246 offset of @var{offset} from the start of the input section,
1247 and is read for @var{count} bytes.
1249 If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
1250 flag set are requested or if the section does not have the
1251 <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
1252 with zeroes. If no errors occur, <<TRUE>> is returned, else
1257 bfd_get_section_contents (abfd, section, location, offset, count)
1262 bfd_size_type count;
1266 if (section->flags & SEC_CONSTRUCTOR)
1268 memset (location, 0, (size_t) count);
1272 /* Even if reloc_done is TRUE, this function reads unrelocated
1273 contents, so we want the raw size. */
1274 sz = section->_raw_size;
1275 if ((bfd_size_type) offset > sz
1277 || offset + count > sz
1278 || count != (size_t) count)
1280 bfd_set_error (bfd_error_bad_value);
1288 if ((section->flags & SEC_HAS_CONTENTS) == 0)
1290 memset (location, 0, (size_t) count);
1294 if ((section->flags & SEC_IN_MEMORY) != 0)
1296 memcpy (location, section->contents + offset, (size_t) count);
1300 return BFD_SEND (abfd, _bfd_get_section_contents,
1301 (abfd, section, location, offset, count));
1306 bfd_copy_private_section_data
1309 bfd_boolean bfd_copy_private_section_data (bfd *ibfd, asection *isec,
1310 bfd *obfd, asection *osec);
1313 Copy private section information from @var{isec} in the BFD
1314 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1315 Return <<TRUE>> on success, <<FALSE>> on error. Possible error
1318 o <<bfd_error_no_memory>> -
1319 Not enough memory exists to create private data for @var{osec}.
1321 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1322 . BFD_SEND (obfd, _bfd_copy_private_section_data, \
1323 . (ibfd, isection, obfd, osection))
1328 _bfd_strip_section_from_output
1331 void _bfd_strip_section_from_output
1332 (struct bfd_link_info *info, asection *section);
1335 Remove @var{section} from the output. If the output section
1336 becomes empty, remove it from the output bfd.
1338 This function won't actually do anything except twiddle flags
1339 if called too late in the linking process, when it's not safe
1343 _bfd_strip_section_from_output (info, s)
1344 struct bfd_link_info *info;
1351 s->flags |= SEC_EXCLUDE;
1353 /* If the section wasn't assigned to an output section, or the
1354 section has been discarded by the linker script, there's nothing
1356 os = s->output_section;
1357 if (os == NULL || os->owner == NULL)
1360 /* If the output section has other (non-excluded) input sections, we
1362 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
1363 for (is = abfd->sections; is != NULL; is = is->next)
1364 if (is->output_section == os && (is->flags & SEC_EXCLUDE) == 0)
1367 /* If the output section is empty, flag it for removal too.
1368 See ldlang.c:strip_excluded_output_sections for the action. */
1369 os->flags |= SEC_EXCLUDE;
1374 bfd_generic_discard_group
1377 bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group);
1380 Remove all members of @var{group} from the output.
1384 bfd_generic_discard_group (abfd, group)
1385 bfd *abfd ATTRIBUTE_UNUSED;
1386 asection *group ATTRIBUTE_UNUSED;