1 /* Object file "section" support for the BFD library.
2 Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004
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 .typedef struct bfd_section
154 . {* The name of the section; the name isn't a copy, the pointer is
155 . the same as that passed to bfd_make_section. *}
158 . {* A unique sequence number. *}
161 . {* Which section in the bfd; 0..n-1 as sections are created in a bfd. *}
164 . {* The next section in the list belonging to the BFD, or NULL. *}
165 . struct bfd_section *next;
167 . {* The field flags contains attributes of the section. Some
168 . flags are read in from the object file, and some are
169 . synthesized from other information. *}
172 .#define SEC_NO_FLAGS 0x000
174 . {* Tells the OS to allocate space for this section when loading.
175 . This is clear for a section containing debug information only. *}
176 .#define SEC_ALLOC 0x001
178 . {* Tells the OS to load the section from the file when loading.
179 . This is clear for a .bss section. *}
180 .#define SEC_LOAD 0x002
182 . {* The section contains data still to be relocated, so there is
183 . some relocation information too. *}
184 .#define SEC_RELOC 0x004
186 . {* A signal to the OS that the section contains read only data. *}
187 .#define SEC_READONLY 0x008
189 . {* The section contains code only. *}
190 .#define SEC_CODE 0x010
192 . {* The section contains data only. *}
193 .#define SEC_DATA 0x020
195 . {* The section will reside in ROM. *}
196 .#define SEC_ROM 0x040
198 . {* The section contains constructor information. This section
199 . type is used by the linker to create lists of constructors and
200 . destructors used by <<g++>>. When a back end sees a symbol
201 . which should be used in a constructor list, it creates a new
202 . section for the type of name (e.g., <<__CTOR_LIST__>>), attaches
203 . the symbol to it, and builds a relocation. To build the lists
204 . of constructors, all the linker has to do is catenate all the
205 . sections called <<__CTOR_LIST__>> and relocate the data
206 . contained within - exactly the operations it would peform on
208 .#define SEC_CONSTRUCTOR 0x080
210 . {* The section has contents - a data section could be
211 . <<SEC_ALLOC>> | <<SEC_HAS_CONTENTS>>; a debug section could be
212 . <<SEC_HAS_CONTENTS>> *}
213 .#define SEC_HAS_CONTENTS 0x100
215 . {* An instruction to the linker to not output the section
216 . even if it has information which would normally be written. *}
217 .#define SEC_NEVER_LOAD 0x200
219 . {* The section contains thread local data. *}
220 .#define SEC_THREAD_LOCAL 0x400
222 . {* The section has GOT references. This flag is only for the
223 . linker, and is currently only used by the elf32-hppa back end.
224 . It will be set if global offset table references were detected
225 . in this section, which indicate to the linker that the section
226 . contains PIC code, and must be handled specially when doing a
228 .#define SEC_HAS_GOT_REF 0x800
230 . {* The section contains common symbols (symbols may be defined
231 . multiple times, the value of a symbol is the amount of
232 . space it requires, and the largest symbol value is the one
233 . used). Most targets have exactly one of these (which we
234 . translate to bfd_com_section_ptr), but ECOFF has two. *}
235 .#define SEC_IS_COMMON 0x1000
237 . {* The section contains only debugging information. For
238 . example, this is set for ELF .debug and .stab sections.
239 . strip tests this flag to see if a section can be
241 .#define SEC_DEBUGGING 0x2000
243 . {* The contents of this section are held in memory pointed to
244 . by the contents field. This is checked by bfd_get_section_contents,
245 . and the data is retrieved from memory if appropriate. *}
246 .#define SEC_IN_MEMORY 0x4000
248 . {* The contents of this section are to be excluded by the
249 . linker for executable and shared objects unless those
250 . objects are to be further relocated. *}
251 .#define SEC_EXCLUDE 0x8000
253 . {* The contents of this section are to be sorted based on the sum of
254 . the symbol and addend values specified by the associated relocation
255 . entries. Entries without associated relocation entries will be
256 . appended to the end of the section in an unspecified order. *}
257 .#define SEC_SORT_ENTRIES 0x10000
259 . {* When linking, duplicate sections of the same name should be
260 . discarded, rather than being combined into a single section as
261 . is usually done. This is similar to how common symbols are
262 . handled. See SEC_LINK_DUPLICATES below. *}
263 .#define SEC_LINK_ONCE 0x20000
265 . {* If SEC_LINK_ONCE is set, this bitfield describes how the linker
266 . should handle duplicate sections. *}
267 .#define SEC_LINK_DUPLICATES 0x40000
269 . {* This value for SEC_LINK_DUPLICATES means that duplicate
270 . sections with the same name should simply be discarded. *}
271 .#define SEC_LINK_DUPLICATES_DISCARD 0x0
273 . {* This value for SEC_LINK_DUPLICATES means that the linker
274 . should warn if there are any duplicate sections, although
275 . it should still only link one copy. *}
276 .#define SEC_LINK_DUPLICATES_ONE_ONLY 0x80000
278 . {* This value for SEC_LINK_DUPLICATES means that the linker
279 . should warn if any duplicate sections are a different size. *}
280 .#define SEC_LINK_DUPLICATES_SAME_SIZE 0x100000
282 . {* This value for SEC_LINK_DUPLICATES means that the linker
283 . should warn if any duplicate sections contain different
285 .#define SEC_LINK_DUPLICATES_SAME_CONTENTS \
286 . (SEC_LINK_DUPLICATES_ONE_ONLY | SEC_LINK_DUPLICATES_SAME_SIZE)
288 . {* This section was created by the linker as part of dynamic
289 . relocation or other arcane processing. It is skipped when
290 . going through the first-pass output, trusting that someone
291 . else up the line will take care of it later. *}
292 .#define SEC_LINKER_CREATED 0x200000
294 . {* This section should not be subject to garbage collection. *}
295 .#define SEC_KEEP 0x400000
297 . {* This section contains "short" data, and should be placed
299 .#define SEC_SMALL_DATA 0x800000
301 . {* Attempt to merge identical entities in the section.
302 . Entity size is given in the entsize field. *}
303 .#define SEC_MERGE 0x1000000
305 . {* If given with SEC_MERGE, entities to merge are zero terminated
306 . strings where entsize specifies character size instead of fixed
308 .#define SEC_STRINGS 0x2000000
310 . {* This section contains data about section groups. *}
311 .#define SEC_GROUP 0x4000000
313 . {* The section is a COFF shared library section. This flag is
314 . only for the linker. If this type of section appears in
315 . the input file, the linker must copy it to the output file
316 . without changing the vma or size. FIXME: Although this
317 . was originally intended to be general, it really is COFF
318 . specific (and the flag was renamed to indicate this). It
319 . might be cleaner to have some more general mechanism to
320 . allow the back end to control what the linker does with
322 .#define SEC_COFF_SHARED_LIBRARY 0x10000000
324 . {* This section contains data which may be shared with other
325 . executables or shared objects. This is for COFF only. *}
326 .#define SEC_COFF_SHARED 0x20000000
328 . {* When a section with this flag is being linked, then if the size of
329 . the input section is less than a page, it should not cross a page
330 . boundary. If the size of the input section is one page or more,
331 . it should be aligned on a page boundary. This is for TI
332 . TMS320C54X only. *}
333 .#define SEC_TIC54X_BLOCK 0x40000000
335 . {* Conditionally link this section; do not link if there are no
336 . references found to any symbol in the section. This is for TI
337 . TMS320C54X only. *}
338 .#define SEC_TIC54X_CLINK 0x80000000
340 . {* End of section flags. *}
342 . {* Some internal packed boolean fields. *}
344 . {* See the vma field. *}
345 . unsigned int user_set_vma : 1;
347 . {* A mark flag used by some of the linker backends. *}
348 . unsigned int linker_mark : 1;
350 . {* Another mark flag used by some of the linker backends. Set for
351 . output sections that have an input section. *}
352 . unsigned int linker_has_input : 1;
354 . {* A mark flag used by some linker backends for garbage collection. *}
355 . unsigned int gc_mark : 1;
357 . {* The following flags are used by the ELF linker. *}
359 . {* Mark sections which have been allocated to segments. *}
360 . unsigned int segment_mark : 1;
362 . {* Type of sec_info information. *}
363 . unsigned int sec_info_type:3;
364 .#define ELF_INFO_TYPE_NONE 0
365 .#define ELF_INFO_TYPE_STABS 1
366 .#define ELF_INFO_TYPE_MERGE 2
367 .#define ELF_INFO_TYPE_EH_FRAME 3
368 .#define ELF_INFO_TYPE_JUST_SYMS 4
370 . {* Nonzero if this section uses RELA relocations, rather than REL. *}
371 . unsigned int use_rela_p:1;
373 . {* Bits used by various backends. The generic code doesn't touch
376 . {* Nonzero if this section has TLS related relocations. *}
377 . unsigned int has_tls_reloc:1;
379 . {* Nonzero if this section has a gp reloc. *}
380 . unsigned int has_gp_reloc:1;
382 . {* Nonzero if this section needs the relax finalize pass. *}
383 . unsigned int need_finalize_relax:1;
385 . {* Whether relocations have been processed. *}
386 . unsigned int reloc_done : 1;
388 . {* End of internal packed boolean fields. *}
390 . {* The virtual memory address of the section - where it will be
391 . at run time. The symbols are relocated against this. The
392 . user_set_vma flag is maintained by bfd; if it's not set, the
393 . backend can assign addresses (for example, in <<a.out>>, where
394 . the default address for <<.data>> is dependent on the specific
395 . target and various flags). *}
398 . {* The load address of the section - where it would be in a
399 . rom image; really only used for writing section header
403 . {* The size of the section in octets, as it will be output.
404 . Contains a value even if the section has no contents (e.g., the
405 . size of <<.bss>>). *}
406 . bfd_size_type size;
408 . {* For input sections, the original size on disk of the section, in
409 . octets. This field is used by the linker relaxation code. It is
410 . currently only set for sections where the linker relaxation scheme
411 . doesn't cache altered section and reloc contents (stabs, eh_frame,
412 . SEC_MERGE, some coff relaxing targets), and thus the original size
413 . needs to be kept to read the section multiple times.
414 . For output sections, rawsize holds the section size calculated on
415 . a previous linker relaxation pass. *}
416 . bfd_size_type rawsize;
418 . {* If this section is going to be output, then this value is the
419 . offset in *bytes* into the output section of the first byte in the
420 . input section (byte ==> smallest addressable unit on the
421 . target). In most cases, if this was going to start at the
422 . 100th octet (8-bit quantity) in the output section, this value
423 . would be 100. However, if the target byte size is 16 bits
424 . (bfd_octets_per_byte is "2"), this value would be 50. *}
425 . bfd_vma output_offset;
427 . {* The output section through which to map on output. *}
428 . struct bfd_section *output_section;
430 . {* The alignment requirement of the section, as an exponent of 2 -
431 . e.g., 3 aligns to 2^3 (or 8). *}
432 . unsigned int alignment_power;
434 . {* If an input section, a pointer to a vector of relocation
435 . records for the data in this section. *}
436 . struct reloc_cache_entry *relocation;
438 . {* If an output section, a pointer to a vector of pointers to
439 . relocation records for the data in this section. *}
440 . struct reloc_cache_entry **orelocation;
442 . {* The number of relocation records in one of the above. *}
443 . unsigned reloc_count;
445 . {* Information below is back end specific - and not always used
448 . {* File position of section data. *}
451 . {* File position of relocation info. *}
452 . file_ptr rel_filepos;
454 . {* File position of line data. *}
455 . file_ptr line_filepos;
457 . {* Pointer to data for applications. *}
460 . {* If the SEC_IN_MEMORY flag is set, this points to the actual
462 . unsigned char *contents;
464 . {* Attached line number information. *}
467 . {* Number of line number records. *}
468 . unsigned int lineno_count;
470 . {* Entity size for merging purposes. *}
471 . unsigned int entsize;
473 . {* Points to the kept section if this section is a link-once section,
474 . and is discarded. *}
475 . struct bfd_section *kept_section;
477 . {* When a section is being output, this value changes as more
478 . linenumbers are written out. *}
479 . file_ptr moving_line_filepos;
481 . {* What the section number is in the target world. *}
486 . {* If this is a constructor section then here is a list of the
487 . relocations created to relocate items within it. *}
488 . struct relent_chain *constructor_chain;
490 . {* The BFD which owns the section. *}
493 . {* A symbol which points at this section only. *}
494 . struct bfd_symbol *symbol;
495 . struct bfd_symbol **symbol_ptr_ptr;
497 . struct bfd_link_order *link_order_head;
498 . struct bfd_link_order *link_order_tail;
501 .{* These sections are global, and are managed by BFD. The application
502 . and target back end are not permitted to change the values in
503 . these sections. New code should use the section_ptr macros rather
504 . than referring directly to the const sections. The const sections
505 . may eventually vanish. *}
506 .#define BFD_ABS_SECTION_NAME "*ABS*"
507 .#define BFD_UND_SECTION_NAME "*UND*"
508 .#define BFD_COM_SECTION_NAME "*COM*"
509 .#define BFD_IND_SECTION_NAME "*IND*"
511 .{* The absolute section. *}
512 .extern asection bfd_abs_section;
513 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
514 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
515 .{* Pointer to the undefined section. *}
516 .extern asection bfd_und_section;
517 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
518 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
519 .{* Pointer to the common section. *}
520 .extern asection bfd_com_section;
521 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
522 .{* Pointer to the indirect section. *}
523 .extern asection bfd_ind_section;
524 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
525 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
527 .#define bfd_is_const_section(SEC) \
528 . ( ((SEC) == bfd_abs_section_ptr) \
529 . || ((SEC) == bfd_und_section_ptr) \
530 . || ((SEC) == bfd_com_section_ptr) \
531 . || ((SEC) == bfd_ind_section_ptr))
533 .extern const struct bfd_symbol * const bfd_abs_symbol;
534 .extern const struct bfd_symbol * const bfd_com_symbol;
535 .extern const struct bfd_symbol * const bfd_und_symbol;
536 .extern const struct bfd_symbol * const bfd_ind_symbol;
538 .{* Macros to handle insertion and deletion of a bfd's sections. These
539 . only handle the list pointers, ie. do not adjust section_count,
540 . target_index etc. *}
541 .#define bfd_section_list_remove(ABFD, PS) \
544 . asection **_ps = PS; \
545 . asection *_s = *_ps; \
547 . if (_s->next == NULL) \
548 . (ABFD)->section_tail = _ps; \
551 .#define bfd_section_list_insert(ABFD, PS, S) \
554 . asection **_ps = PS; \
555 . asection *_s = S; \
558 . if (_s->next == NULL) \
559 . (ABFD)->section_tail = &_s->next; \
565 /* We use a macro to initialize the static asymbol structures because
566 traditional C does not permit us to initialize a union member while
567 gcc warns if we don't initialize it. */
568 /* the_bfd, name, value, attr, section [, udata] */
570 #define GLOBAL_SYM_INIT(NAME, SECTION) \
571 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION, { 0 }}
573 #define GLOBAL_SYM_INIT(NAME, SECTION) \
574 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION }
577 /* These symbols are global, not specific to any BFD. Therefore, anything
578 that tries to change them is broken, and should be repaired. */
580 static const asymbol global_syms[] =
582 GLOBAL_SYM_INIT (BFD_COM_SECTION_NAME, &bfd_com_section),
583 GLOBAL_SYM_INIT (BFD_UND_SECTION_NAME, &bfd_und_section),
584 GLOBAL_SYM_INIT (BFD_ABS_SECTION_NAME, &bfd_abs_section),
585 GLOBAL_SYM_INIT (BFD_IND_SECTION_NAME, &bfd_ind_section)
588 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
589 const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
591 /* name, id, index, next, flags, user_set_vma, */ \
592 { NAME, IDX, 0, NULL, FLAGS, 0, \
594 /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \
597 /* sec_info_type, use_rela_p, has_tls_reloc, has_gp_reloc, */ \
600 /* need_finalize_relax, reloc_done, */ \
603 /* vma, lma, size, rawsize */ \
606 /* output_offset, output_section, alignment_power, */ \
607 0, (struct bfd_section *) &SEC, 0, \
609 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
610 NULL, NULL, 0, 0, 0, \
612 /* line_filepos, userdata, contents, lineno, lineno_count, */ \
613 0, NULL, NULL, NULL, 0, \
615 /* entsize, kept_section, moving_line_filepos, */ \
618 /* target_index, used_by_bfd, constructor_chain, owner, */ \
619 0, NULL, NULL, NULL, \
622 (struct bfd_symbol *) &global_syms[IDX], \
624 /* symbol_ptr_ptr, */ \
625 (struct bfd_symbol **) &SYM, \
627 /* link_order_head, link_order_tail */ \
631 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
632 BFD_COM_SECTION_NAME, 0);
633 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
634 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
635 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
638 struct section_hash_entry
640 struct bfd_hash_entry root;
644 /* Initialize an entry in the section hash table. */
646 struct bfd_hash_entry *
647 bfd_section_hash_newfunc (struct bfd_hash_entry *entry,
648 struct bfd_hash_table *table,
651 /* Allocate the structure if it has not already been allocated by a
655 entry = (struct bfd_hash_entry *)
656 bfd_hash_allocate (table, sizeof (struct section_hash_entry));
661 /* Call the allocation method of the superclass. */
662 entry = bfd_hash_newfunc (entry, table, string);
664 memset (&((struct section_hash_entry *) entry)->section, 0,
670 #define section_hash_lookup(table, string, create, copy) \
671 ((struct section_hash_entry *) \
672 bfd_hash_lookup ((table), (string), (create), (copy)))
674 /* Initializes a new section. NEWSECT->NAME is already set. */
677 bfd_section_init (bfd *abfd, asection *newsect)
679 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */
681 newsect->id = section_id;
682 newsect->index = abfd->section_count;
683 newsect->owner = abfd;
685 /* Create a symbol whose only job is to point to this section. This
686 is useful for things like relocs which are relative to the base
688 newsect->symbol = bfd_make_empty_symbol (abfd);
689 if (newsect->symbol == NULL)
692 newsect->symbol->name = newsect->name;
693 newsect->symbol->value = 0;
694 newsect->symbol->section = newsect;
695 newsect->symbol->flags = BSF_SECTION_SYM;
697 newsect->symbol_ptr_ptr = &newsect->symbol;
699 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect)))
703 abfd->section_count++;
704 *abfd->section_tail = newsect;
705 abfd->section_tail = &newsect->next;
712 section prototypes, , typedef asection, Sections
716 These are the functions exported by the section handling part of BFD.
721 bfd_section_list_clear
724 void bfd_section_list_clear (bfd *);
727 Clears the section list, and also resets the section count and
732 bfd_section_list_clear (bfd *abfd)
734 abfd->sections = NULL;
735 abfd->section_tail = &abfd->sections;
736 abfd->section_count = 0;
737 memset (abfd->section_htab.table, 0,
738 abfd->section_htab.size * sizeof (struct bfd_hash_entry *));
743 bfd_get_section_by_name
746 asection *bfd_get_section_by_name (bfd *abfd, const char *name);
749 Run through @var{abfd} and return the one of the
750 <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
751 @xref{Sections}, for more information.
753 This should only be used in special cases; the normal way to process
754 all sections of a given name is to use <<bfd_map_over_sections>> and
755 <<strcmp>> on the name (or better yet, base it on the section flags
756 or something else) for each section.
760 bfd_get_section_by_name (bfd *abfd, const char *name)
762 struct section_hash_entry *sh;
764 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
773 bfd_get_section_by_name_if
776 asection *bfd_get_section_by_name_if
779 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),
783 Call the provided function @var{func} for each section
784 attached to the BFD @var{abfd} whose name matches @var{name},
785 passing @var{obj} as an argument. The function will be called
788 | func (abfd, the_section, obj);
790 It returns the first section for which @var{func} returns true,
796 bfd_get_section_by_name_if (bfd *abfd, const char *name,
797 bfd_boolean (*operation) (bfd *,
802 struct section_hash_entry *sh;
805 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
809 hash = sh->root.hash;
812 if ((*operation) (abfd, &sh->section, user_storage))
814 sh = (struct section_hash_entry *) sh->root.next;
816 while (sh != NULL && sh->root.hash == hash
817 && strcmp (sh->root.string, name) == 0);
824 bfd_get_unique_section_name
827 char *bfd_get_unique_section_name
828 (bfd *abfd, const char *templat, int *count);
831 Invent a section name that is unique in @var{abfd} by tacking
832 a dot and a digit suffix onto the original @var{templat}. If
833 @var{count} is non-NULL, then it specifies the first number
834 tried as a suffix to generate a unique name. The value
835 pointed to by @var{count} will be incremented in this case.
839 bfd_get_unique_section_name (bfd *abfd, const char *templat, int *count)
845 len = strlen (templat);
846 sname = bfd_malloc (len + 8);
849 memcpy (sname, templat, len);
856 /* If we have a million sections, something is badly wrong. */
859 sprintf (sname + len, ".%d", num++);
861 while (section_hash_lookup (&abfd->section_htab, sname, FALSE, FALSE));
870 bfd_make_section_old_way
873 asection *bfd_make_section_old_way (bfd *abfd, const char *name);
876 Create a new empty section called @var{name}
877 and attach it to the end of the chain of sections for the
878 BFD @var{abfd}. An attempt to create a section with a name which
879 is already in use returns its pointer without changing the
882 It has the funny name since this is the way it used to be
883 before it was rewritten....
886 o <<bfd_error_invalid_operation>> -
887 If output has already started for this BFD.
888 o <<bfd_error_no_memory>> -
889 If memory allocation fails.
894 bfd_make_section_old_way (bfd *abfd, const char *name)
896 struct section_hash_entry *sh;
899 if (abfd->output_has_begun)
901 bfd_set_error (bfd_error_invalid_operation);
905 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
906 return bfd_abs_section_ptr;
908 if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
909 return bfd_com_section_ptr;
911 if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
912 return bfd_und_section_ptr;
914 if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
915 return bfd_ind_section_ptr;
917 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
921 newsect = &sh->section;
922 if (newsect->name != NULL)
924 /* Section already exists. */
928 newsect->name = name;
929 return bfd_section_init (abfd, newsect);
934 bfd_make_section_anyway
937 asection *bfd_make_section_anyway (bfd *abfd, const char *name);
940 Create a new empty section called @var{name} and attach it to the end of
941 the chain of sections for @var{abfd}. Create a new section even if there
942 is already a section with that name.
944 Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
945 o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
946 o <<bfd_error_no_memory>> - If memory allocation fails.
950 bfd_make_section_anyway (bfd *abfd, const char *name)
952 struct section_hash_entry *sh;
955 if (abfd->output_has_begun)
957 bfd_set_error (bfd_error_invalid_operation);
961 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
965 newsect = &sh->section;
966 if (newsect->name != NULL)
968 /* We are making a section of the same name. Put it in the
969 section hash table. Even though we can't find it directly by a
970 hash lookup, we'll be able to find the section by traversing
971 sh->root.next quicker than looking at all the bfd sections. */
972 struct section_hash_entry *new_sh;
973 new_sh = (struct section_hash_entry *)
974 bfd_section_hash_newfunc (NULL, &abfd->section_htab, name);
978 new_sh->root = sh->root;
979 sh->root.next = &new_sh->root;
980 newsect = &new_sh->section;
983 newsect->name = name;
984 return bfd_section_init (abfd, newsect);
992 asection *bfd_make_section (bfd *, const char *name);
995 Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
996 bfd_set_error ()) without changing the section chain if there is already a
997 section named @var{name}. If there is an error, return <<NULL>> and set
1002 bfd_make_section (bfd *abfd, const char *name)
1004 struct section_hash_entry *sh;
1007 if (abfd->output_has_begun)
1009 bfd_set_error (bfd_error_invalid_operation);
1013 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0
1014 || strcmp (name, BFD_COM_SECTION_NAME) == 0
1015 || strcmp (name, BFD_UND_SECTION_NAME) == 0
1016 || strcmp (name, BFD_IND_SECTION_NAME) == 0)
1019 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
1023 newsect = &sh->section;
1024 if (newsect->name != NULL)
1026 /* Section already exists. */
1030 newsect->name = name;
1031 return bfd_section_init (abfd, newsect);
1036 bfd_set_section_flags
1039 bfd_boolean bfd_set_section_flags
1040 (bfd *abfd, asection *sec, flagword flags);
1043 Set the attributes of the section @var{sec} in the BFD
1044 @var{abfd} to the value @var{flags}. Return <<TRUE>> on success,
1045 <<FALSE>> on error. Possible error returns are:
1047 o <<bfd_error_invalid_operation>> -
1048 The section cannot have one or more of the attributes
1049 requested. For example, a .bss section in <<a.out>> may not
1050 have the <<SEC_HAS_CONTENTS>> field set.
1055 bfd_set_section_flags (bfd *abfd ATTRIBUTE_UNUSED,
1059 section->flags = flags;
1065 bfd_map_over_sections
1068 void bfd_map_over_sections
1070 void (*func) (bfd *abfd, asection *sect, void *obj),
1074 Call the provided function @var{func} for each section
1075 attached to the BFD @var{abfd}, passing @var{obj} as an
1076 argument. The function will be called as if by
1078 | func (abfd, the_section, obj);
1080 This is the preferred method for iterating over sections; an
1081 alternative would be to use a loop:
1084 | for (p = abfd->sections; p != NULL; p = p->next)
1085 | func (abfd, p, ...)
1090 bfd_map_over_sections (bfd *abfd,
1091 void (*operation) (bfd *, asection *, void *),
1097 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
1098 (*operation) (abfd, sect, user_storage);
1100 if (i != abfd->section_count) /* Debugging */
1106 bfd_sections_find_if
1109 asection *bfd_sections_find_if
1111 bfd_boolean (*operation) (bfd *abfd, asection *sect, void *obj),
1115 Call the provided function @var{operation} for each section
1116 attached to the BFD @var{abfd}, passing @var{obj} as an
1117 argument. The function will be called as if by
1119 | operation (abfd, the_section, obj);
1121 It returns the first section for which @var{operation} returns true.
1126 bfd_sections_find_if (bfd *abfd,
1127 bfd_boolean (*operation) (bfd *, asection *, void *),
1132 for (sect = abfd->sections; sect != NULL; sect = sect->next)
1133 if ((*operation) (abfd, sect, user_storage))
1141 bfd_set_section_size
1144 bfd_boolean bfd_set_section_size
1145 (bfd *abfd, asection *sec, bfd_size_type val);
1148 Set @var{sec} to the size @var{val}. If the operation is
1149 ok, then <<TRUE>> is returned, else <<FALSE>>.
1151 Possible error returns:
1152 o <<bfd_error_invalid_operation>> -
1153 Writing has started to the BFD, so setting the size is invalid.
1158 bfd_set_section_size (bfd *abfd, sec_ptr ptr, bfd_size_type val)
1160 /* Once you've started writing to any section you cannot create or change
1161 the size of any others. */
1163 if (abfd->output_has_begun)
1165 bfd_set_error (bfd_error_invalid_operation);
1175 bfd_set_section_contents
1178 bfd_boolean bfd_set_section_contents
1179 (bfd *abfd, asection *section, const void *data,
1180 file_ptr offset, bfd_size_type count);
1183 Sets the contents of the section @var{section} in BFD
1184 @var{abfd} to the data starting in memory at @var{data}. The
1185 data is written to the output section starting at offset
1186 @var{offset} for @var{count} octets.
1188 Normally <<TRUE>> is returned, else <<FALSE>>. Possible error
1190 o <<bfd_error_no_contents>> -
1191 The output section does not have the <<SEC_HAS_CONTENTS>>
1192 attribute, so nothing can be written to it.
1195 This routine is front end to the back end function
1196 <<_bfd_set_section_contents>>.
1201 bfd_set_section_contents (bfd *abfd,
1203 const void *location,
1205 bfd_size_type count)
1209 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
1211 bfd_set_error (bfd_error_no_contents);
1216 if ((bfd_size_type) offset > sz
1218 || offset + count > sz
1219 || count != (size_t) count)
1221 bfd_set_error (bfd_error_bad_value);
1225 switch (abfd->direction)
1227 case read_direction:
1229 bfd_set_error (bfd_error_invalid_operation);
1232 case write_direction:
1235 case both_direction:
1236 /* File is opened for update. `output_has_begun' some time ago when
1237 the file was created. Do not recompute sections sizes or alignments
1238 in _bfd_set_section_content. */
1239 abfd->output_has_begun = TRUE;
1243 /* Record a copy of the data in memory if desired. */
1244 if (section->contents
1245 && location != section->contents + offset)
1246 memcpy (section->contents + offset, location, (size_t) count);
1248 if (BFD_SEND (abfd, _bfd_set_section_contents,
1249 (abfd, section, location, offset, count)))
1251 abfd->output_has_begun = TRUE;
1260 bfd_get_section_contents
1263 bfd_boolean bfd_get_section_contents
1264 (bfd *abfd, asection *section, void *location, file_ptr offset,
1265 bfd_size_type count);
1268 Read data from @var{section} in BFD @var{abfd}
1269 into memory starting at @var{location}. The data is read at an
1270 offset of @var{offset} from the start of the input section,
1271 and is read for @var{count} bytes.
1273 If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
1274 flag set are requested or if the section does not have the
1275 <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
1276 with zeroes. If no errors occur, <<TRUE>> is returned, else
1281 bfd_get_section_contents (bfd *abfd,
1285 bfd_size_type count)
1289 if (section->flags & SEC_CONSTRUCTOR)
1291 memset (location, 0, (size_t) count);
1295 sz = section->rawsize ? section->rawsize : section->size;
1296 if ((bfd_size_type) offset > sz
1298 || offset + count > sz
1299 || count != (size_t) count)
1301 bfd_set_error (bfd_error_bad_value);
1309 if ((section->flags & SEC_HAS_CONTENTS) == 0)
1311 memset (location, 0, (size_t) count);
1315 if ((section->flags & SEC_IN_MEMORY) != 0)
1317 memcpy (location, section->contents + offset, (size_t) count);
1321 return BFD_SEND (abfd, _bfd_get_section_contents,
1322 (abfd, section, location, offset, count));
1327 bfd_malloc_and_get_section
1330 bfd_boolean bfd_malloc_and_get_section
1331 (bfd *abfd, asection *section, bfd_byte **buf);
1334 Read all data from @var{section} in BFD @var{abfd}
1335 into a buffer, *@var{buf}, malloc'd by this function.
1339 bfd_malloc_and_get_section (bfd *abfd, sec_ptr sec, bfd_byte **buf)
1341 bfd_size_type sz = sec->rawsize ? sec->rawsize : sec->size;
1348 p = bfd_malloc (sec->rawsize > sec->size ? sec->rawsize : sec->size);
1353 return bfd_get_section_contents (abfd, sec, p, 0, sz);
1357 bfd_copy_private_section_data
1360 bfd_boolean bfd_copy_private_section_data
1361 (bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
1364 Copy private section information from @var{isec} in the BFD
1365 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1366 Return <<TRUE>> on success, <<FALSE>> on error. Possible error
1369 o <<bfd_error_no_memory>> -
1370 Not enough memory exists to create private data for @var{osec}.
1372 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1373 . BFD_SEND (obfd, _bfd_copy_private_section_data, \
1374 . (ibfd, isection, obfd, osection))
1379 _bfd_strip_section_from_output
1382 void _bfd_strip_section_from_output
1383 (struct bfd_link_info *info, asection *section);
1386 Remove @var{section} from the output. If the output section
1387 becomes empty, remove it from the output bfd.
1389 This function won't actually do anything except twiddle flags
1390 if called too late in the linking process, when it's not safe
1394 _bfd_strip_section_from_output (struct bfd_link_info *info, asection *s)
1400 s->flags |= SEC_EXCLUDE;
1402 /* If the section wasn't assigned to an output section, or the
1403 section has been discarded by the linker script, there's nothing
1405 os = s->output_section;
1406 if (os == NULL || os->owner == NULL)
1409 /* If the output section has other (non-excluded) input sections, we
1411 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
1412 for (is = abfd->sections; is != NULL; is = is->next)
1413 if (is->output_section == os && (is->flags & SEC_EXCLUDE) == 0)
1416 /* If the output section is empty, flag it for removal too.
1417 See ldlang.c:strip_excluded_output_sections for the action. */
1418 os->flags |= SEC_EXCLUDE;
1423 bfd_generic_is_group_section
1426 bfd_boolean bfd_generic_is_group_section (bfd *, const asection *sec);
1429 Returns TRUE if @var{sec} is a member of a group.
1433 bfd_generic_is_group_section (bfd *abfd ATTRIBUTE_UNUSED,
1434 const asection *sec ATTRIBUTE_UNUSED)
1441 bfd_generic_discard_group
1444 bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group);
1447 Remove all members of @var{group} from the output.
1451 bfd_generic_discard_group (bfd *abfd ATTRIBUTE_UNUSED,
1452 asection *group ATTRIBUTE_UNUSED)