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, 2005
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 previous section in the list belonging to the BFD, or NULL. *}
168 . struct bfd_section *prev;
170 . {* The field flags contains attributes of the section. Some
171 . flags are read in from the object file, and some are
172 . synthesized from other information. *}
175 .#define SEC_NO_FLAGS 0x000
177 . {* Tells the OS to allocate space for this section when loading.
178 . This is clear for a section containing debug information only. *}
179 .#define SEC_ALLOC 0x001
181 . {* Tells the OS to load the section from the file when loading.
182 . This is clear for a .bss section. *}
183 .#define SEC_LOAD 0x002
185 . {* The section contains data still to be relocated, so there is
186 . some relocation information too. *}
187 .#define SEC_RELOC 0x004
189 . {* A signal to the OS that the section contains read only data. *}
190 .#define SEC_READONLY 0x008
192 . {* The section contains code only. *}
193 .#define SEC_CODE 0x010
195 . {* The section contains data only. *}
196 .#define SEC_DATA 0x020
198 . {* The section will reside in ROM. *}
199 .#define SEC_ROM 0x040
201 . {* The section contains constructor information. This section
202 . type is used by the linker to create lists of constructors and
203 . destructors used by <<g++>>. When a back end sees a symbol
204 . which should be used in a constructor list, it creates a new
205 . section for the type of name (e.g., <<__CTOR_LIST__>>), attaches
206 . the symbol to it, and builds a relocation. To build the lists
207 . of constructors, all the linker has to do is catenate all the
208 . sections called <<__CTOR_LIST__>> and relocate the data
209 . contained within - exactly the operations it would peform on
211 .#define SEC_CONSTRUCTOR 0x080
213 . {* The section has contents - a data section could be
214 . <<SEC_ALLOC>> | <<SEC_HAS_CONTENTS>>; a debug section could be
215 . <<SEC_HAS_CONTENTS>> *}
216 .#define SEC_HAS_CONTENTS 0x100
218 . {* An instruction to the linker to not output the section
219 . even if it has information which would normally be written. *}
220 .#define SEC_NEVER_LOAD 0x200
222 . {* The section contains thread local data. *}
223 .#define SEC_THREAD_LOCAL 0x400
225 . {* The section has GOT references. This flag is only for the
226 . linker, and is currently only used by the elf32-hppa back end.
227 . It will be set if global offset table references were detected
228 . in this section, which indicate to the linker that the section
229 . contains PIC code, and must be handled specially when doing a
231 .#define SEC_HAS_GOT_REF 0x800
233 . {* The section contains common symbols (symbols may be defined
234 . multiple times, the value of a symbol is the amount of
235 . space it requires, and the largest symbol value is the one
236 . used). Most targets have exactly one of these (which we
237 . translate to bfd_com_section_ptr), but ECOFF has two. *}
238 .#define SEC_IS_COMMON 0x1000
240 . {* The section contains only debugging information. For
241 . example, this is set for ELF .debug and .stab sections.
242 . strip tests this flag to see if a section can be
244 .#define SEC_DEBUGGING 0x2000
246 . {* The contents of this section are held in memory pointed to
247 . by the contents field. This is checked by bfd_get_section_contents,
248 . and the data is retrieved from memory if appropriate. *}
249 .#define SEC_IN_MEMORY 0x4000
251 . {* The contents of this section are to be excluded by the
252 . linker for executable and shared objects unless those
253 . objects are to be further relocated. *}
254 .#define SEC_EXCLUDE 0x8000
256 . {* The contents of this section are to be sorted based on the sum of
257 . the symbol and addend values specified by the associated relocation
258 . entries. Entries without associated relocation entries will be
259 . appended to the end of the section in an unspecified order. *}
260 .#define SEC_SORT_ENTRIES 0x10000
262 . {* When linking, duplicate sections of the same name should be
263 . discarded, rather than being combined into a single section as
264 . is usually done. This is similar to how common symbols are
265 . handled. See SEC_LINK_DUPLICATES below. *}
266 .#define SEC_LINK_ONCE 0x20000
268 . {* If SEC_LINK_ONCE is set, this bitfield describes how the linker
269 . should handle duplicate sections. *}
270 .#define SEC_LINK_DUPLICATES 0x40000
272 . {* This value for SEC_LINK_DUPLICATES means that duplicate
273 . sections with the same name should simply be discarded. *}
274 .#define SEC_LINK_DUPLICATES_DISCARD 0x0
276 . {* This value for SEC_LINK_DUPLICATES means that the linker
277 . should warn if there are any duplicate sections, although
278 . it should still only link one copy. *}
279 .#define SEC_LINK_DUPLICATES_ONE_ONLY 0x80000
281 . {* This value for SEC_LINK_DUPLICATES means that the linker
282 . should warn if any duplicate sections are a different size. *}
283 .#define SEC_LINK_DUPLICATES_SAME_SIZE 0x100000
285 . {* This value for SEC_LINK_DUPLICATES means that the linker
286 . should warn if any duplicate sections contain different
288 .#define SEC_LINK_DUPLICATES_SAME_CONTENTS \
289 . (SEC_LINK_DUPLICATES_ONE_ONLY | SEC_LINK_DUPLICATES_SAME_SIZE)
291 . {* This section was created by the linker as part of dynamic
292 . relocation or other arcane processing. It is skipped when
293 . going through the first-pass output, trusting that someone
294 . else up the line will take care of it later. *}
295 .#define SEC_LINKER_CREATED 0x200000
297 . {* This section should not be subject to garbage collection. *}
298 .#define SEC_KEEP 0x400000
300 . {* This section contains "short" data, and should be placed
302 .#define SEC_SMALL_DATA 0x800000
304 . {* Attempt to merge identical entities in the section.
305 . Entity size is given in the entsize field. *}
306 .#define SEC_MERGE 0x1000000
308 . {* If given with SEC_MERGE, entities to merge are zero terminated
309 . strings where entsize specifies character size instead of fixed
311 .#define SEC_STRINGS 0x2000000
313 . {* This section contains data about section groups. *}
314 .#define SEC_GROUP 0x4000000
316 . {* The section is a COFF shared library section. This flag is
317 . only for the linker. If this type of section appears in
318 . the input file, the linker must copy it to the output file
319 . without changing the vma or size. FIXME: Although this
320 . was originally intended to be general, it really is COFF
321 . specific (and the flag was renamed to indicate this). It
322 . might be cleaner to have some more general mechanism to
323 . allow the back end to control what the linker does with
325 .#define SEC_COFF_SHARED_LIBRARY 0x10000000
327 . {* This section contains data which may be shared with other
328 . executables or shared objects. This is for COFF only. *}
329 .#define SEC_COFF_SHARED 0x20000000
331 . {* When a section with this flag is being linked, then if the size of
332 . the input section is less than a page, it should not cross a page
333 . boundary. If the size of the input section is one page or more,
334 . it should be aligned on a page boundary. This is for TI
335 . TMS320C54X only. *}
336 .#define SEC_TIC54X_BLOCK 0x40000000
338 . {* Conditionally link this section; do not link if there are no
339 . references found to any symbol in the section. This is for TI
340 . TMS320C54X only. *}
341 .#define SEC_TIC54X_CLINK 0x80000000
343 . {* End of section flags. *}
345 . {* Some internal packed boolean fields. *}
347 . {* See the vma field. *}
348 . unsigned int user_set_vma : 1;
350 . {* A mark flag used by some of the linker backends. *}
351 . unsigned int linker_mark : 1;
353 . {* Another mark flag used by some of the linker backends. Set for
354 . output sections that have an input section. *}
355 . unsigned int linker_has_input : 1;
357 . {* A mark flag used by some linker backends for garbage collection. *}
358 . unsigned int gc_mark : 1;
360 . {* The following flags are used by the ELF linker. *}
362 . {* Mark sections which have been allocated to segments. *}
363 . unsigned int segment_mark : 1;
365 . {* Type of sec_info information. *}
366 . unsigned int sec_info_type:3;
367 .#define ELF_INFO_TYPE_NONE 0
368 .#define ELF_INFO_TYPE_STABS 1
369 .#define ELF_INFO_TYPE_MERGE 2
370 .#define ELF_INFO_TYPE_EH_FRAME 3
371 .#define ELF_INFO_TYPE_JUST_SYMS 4
373 . {* Nonzero if this section uses RELA relocations, rather than REL. *}
374 . unsigned int use_rela_p:1;
376 . {* Bits used by various backends. The generic code doesn't touch
379 . {* Nonzero if this section has TLS related relocations. *}
380 . unsigned int has_tls_reloc:1;
382 . {* Nonzero if this section has a gp reloc. *}
383 . unsigned int has_gp_reloc:1;
385 . {* Nonzero if this section needs the relax finalize pass. *}
386 . unsigned int need_finalize_relax:1;
388 . {* Whether relocations have been processed. *}
389 . unsigned int reloc_done : 1;
391 . {* End of internal packed boolean fields. *}
393 . {* The virtual memory address of the section - where it will be
394 . at run time. The symbols are relocated against this. The
395 . user_set_vma flag is maintained by bfd; if it's not set, the
396 . backend can assign addresses (for example, in <<a.out>>, where
397 . the default address for <<.data>> is dependent on the specific
398 . target and various flags). *}
401 . {* The load address of the section - where it would be in a
402 . rom image; really only used for writing section header
406 . {* The size of the section in octets, as it will be output.
407 . Contains a value even if the section has no contents (e.g., the
408 . size of <<.bss>>). *}
409 . bfd_size_type size;
411 . {* For input sections, the original size on disk of the section, in
412 . octets. This field is used by the linker relaxation code. It is
413 . currently only set for sections where the linker relaxation scheme
414 . doesn't cache altered section and reloc contents (stabs, eh_frame,
415 . SEC_MERGE, some coff relaxing targets), and thus the original size
416 . needs to be kept to read the section multiple times.
417 . For output sections, rawsize holds the section size calculated on
418 . a previous linker relaxation pass. *}
419 . bfd_size_type rawsize;
421 . {* If this section is going to be output, then this value is the
422 . offset in *bytes* into the output section of the first byte in the
423 . input section (byte ==> smallest addressable unit on the
424 . target). In most cases, if this was going to start at the
425 . 100th octet (8-bit quantity) in the output section, this value
426 . would be 100. However, if the target byte size is 16 bits
427 . (bfd_octets_per_byte is "2"), this value would be 50. *}
428 . bfd_vma output_offset;
430 . {* The output section through which to map on output. *}
431 . struct bfd_section *output_section;
433 . {* The alignment requirement of the section, as an exponent of 2 -
434 . e.g., 3 aligns to 2^3 (or 8). *}
435 . unsigned int alignment_power;
437 . {* If an input section, a pointer to a vector of relocation
438 . records for the data in this section. *}
439 . struct reloc_cache_entry *relocation;
441 . {* If an output section, a pointer to a vector of pointers to
442 . relocation records for the data in this section. *}
443 . struct reloc_cache_entry **orelocation;
445 . {* The number of relocation records in one of the above. *}
446 . unsigned reloc_count;
448 . {* Information below is back end specific - and not always used
451 . {* File position of section data. *}
454 . {* File position of relocation info. *}
455 . file_ptr rel_filepos;
457 . {* File position of line data. *}
458 . file_ptr line_filepos;
460 . {* Pointer to data for applications. *}
463 . {* If the SEC_IN_MEMORY flag is set, this points to the actual
465 . unsigned char *contents;
467 . {* Attached line number information. *}
470 . {* Number of line number records. *}
471 . unsigned int lineno_count;
473 . {* Entity size for merging purposes. *}
474 . unsigned int entsize;
476 . {* Points to the kept section if this section is a link-once section,
477 . and is discarded. *}
478 . struct bfd_section *kept_section;
480 . {* When a section is being output, this value changes as more
481 . linenumbers are written out. *}
482 . file_ptr moving_line_filepos;
484 . {* What the section number is in the target world. *}
489 . {* If this is a constructor section then here is a list of the
490 . relocations created to relocate items within it. *}
491 . struct relent_chain *constructor_chain;
493 . {* The BFD which owns the section. *}
496 . {* A symbol which points at this section only. *}
497 . struct bfd_symbol *symbol;
498 . struct bfd_symbol **symbol_ptr_ptr;
500 . struct bfd_link_order *link_order_head;
501 . struct bfd_link_order *link_order_tail;
504 .{* These sections are global, and are managed by BFD. The application
505 . and target back end are not permitted to change the values in
506 . these sections. New code should use the section_ptr macros rather
507 . than referring directly to the const sections. The const sections
508 . may eventually vanish. *}
509 .#define BFD_ABS_SECTION_NAME "*ABS*"
510 .#define BFD_UND_SECTION_NAME "*UND*"
511 .#define BFD_COM_SECTION_NAME "*COM*"
512 .#define BFD_IND_SECTION_NAME "*IND*"
514 .{* The absolute section. *}
515 .extern asection bfd_abs_section;
516 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
517 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
518 .{* Pointer to the undefined section. *}
519 .extern asection bfd_und_section;
520 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
521 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
522 .{* Pointer to the common section. *}
523 .extern asection bfd_com_section;
524 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
525 .{* Pointer to the indirect section. *}
526 .extern asection bfd_ind_section;
527 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
528 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
530 .#define bfd_is_const_section(SEC) \
531 . ( ((SEC) == bfd_abs_section_ptr) \
532 . || ((SEC) == bfd_und_section_ptr) \
533 . || ((SEC) == bfd_com_section_ptr) \
534 . || ((SEC) == bfd_ind_section_ptr))
536 .extern const struct bfd_symbol * const bfd_abs_symbol;
537 .extern const struct bfd_symbol * const bfd_com_symbol;
538 .extern const struct bfd_symbol * const bfd_und_symbol;
539 .extern const struct bfd_symbol * const bfd_ind_symbol;
541 .{* Macros to handle insertion and deletion of a bfd's sections. These
542 . only handle the list pointers, ie. do not adjust section_count,
543 . target_index etc. *}
544 .#define bfd_section_list_remove(ABFD, S) \
547 . asection *_s = S; \
548 . asection *_next = _s->next; \
549 . asection *_prev = _s->prev; \
551 . _prev->next = _next; \
553 . (ABFD)->sections = _next; \
555 . _next->prev = _prev; \
557 . (ABFD)->section_last = _prev; \
560 .#define bfd_section_list_append(ABFD, S) \
563 . asection *_s = S; \
564 . bfd *_abfd = ABFD; \
566 . if (_abfd->section_last) \
568 . _s->prev = _abfd->section_last; \
569 . _abfd->section_last->next = _s; \
574 . _abfd->sections = _s; \
576 . _abfd->section_last = _s; \
579 .#define bfd_section_list_prepend(ABFD, S) \
582 . asection *_s = S; \
583 . bfd *_abfd = ABFD; \
585 . if (_abfd->sections) \
587 . _s->next = _abfd->sections; \
588 . _abfd->sections->prev = _s; \
593 . _abfd->section_last = _s; \
595 . _abfd->sections = _s; \
598 .#define bfd_section_list_insert_after(ABFD, A, S) \
601 . asection *_a = A; \
602 . asection *_s = S; \
603 . asection *_next = _a->next; \
604 . _s->next = _next; \
608 . _next->prev = _s; \
610 . (ABFD)->section_last = _s; \
613 .#define bfd_section_list_insert_before(ABFD, B, S) \
616 . asection *_b = B; \
617 . asection *_s = S; \
618 . asection *_prev = _b->prev; \
619 . _s->prev = _prev; \
623 . _prev->next = _s; \
625 . (ABFD)->sections = _s; \
628 .#define bfd_section_removed_from_list(ABFD, S) \
629 . ((S)->next == NULL ? (ABFD)->section_last != (S) : (S)->next->prev != (S))
633 /* We use a macro to initialize the static asymbol structures because
634 traditional C does not permit us to initialize a union member while
635 gcc warns if we don't initialize it. */
636 /* the_bfd, name, value, attr, section [, udata] */
638 #define GLOBAL_SYM_INIT(NAME, SECTION) \
639 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION, { 0 }}
641 #define GLOBAL_SYM_INIT(NAME, SECTION) \
642 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION }
645 /* These symbols are global, not specific to any BFD. Therefore, anything
646 that tries to change them is broken, and should be repaired. */
648 static const asymbol global_syms[] =
650 GLOBAL_SYM_INIT (BFD_COM_SECTION_NAME, &bfd_com_section),
651 GLOBAL_SYM_INIT (BFD_UND_SECTION_NAME, &bfd_und_section),
652 GLOBAL_SYM_INIT (BFD_ABS_SECTION_NAME, &bfd_abs_section),
653 GLOBAL_SYM_INIT (BFD_IND_SECTION_NAME, &bfd_ind_section)
656 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
657 const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
659 /* name, id, index, next, prev, flags, user_set_vma, */ \
660 { NAME, IDX, 0, NULL, NULL, FLAGS, 0, \
662 /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \
665 /* sec_info_type, use_rela_p, has_tls_reloc, has_gp_reloc, */ \
668 /* need_finalize_relax, reloc_done, */ \
671 /* vma, lma, size, rawsize */ \
674 /* output_offset, output_section, alignment_power, */ \
675 0, (struct bfd_section *) &SEC, 0, \
677 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
678 NULL, NULL, 0, 0, 0, \
680 /* line_filepos, userdata, contents, lineno, lineno_count, */ \
681 0, NULL, NULL, NULL, 0, \
683 /* entsize, kept_section, moving_line_filepos, */ \
686 /* target_index, used_by_bfd, constructor_chain, owner, */ \
687 0, NULL, NULL, NULL, \
690 (struct bfd_symbol *) &global_syms[IDX], \
692 /* symbol_ptr_ptr, */ \
693 (struct bfd_symbol **) &SYM, \
695 /* link_order_head, link_order_tail */ \
699 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
700 BFD_COM_SECTION_NAME, 0);
701 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
702 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
703 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
706 struct section_hash_entry
708 struct bfd_hash_entry root;
712 /* Initialize an entry in the section hash table. */
714 struct bfd_hash_entry *
715 bfd_section_hash_newfunc (struct bfd_hash_entry *entry,
716 struct bfd_hash_table *table,
719 /* Allocate the structure if it has not already been allocated by a
723 entry = (struct bfd_hash_entry *)
724 bfd_hash_allocate (table, sizeof (struct section_hash_entry));
729 /* Call the allocation method of the superclass. */
730 entry = bfd_hash_newfunc (entry, table, string);
732 memset (&((struct section_hash_entry *) entry)->section, 0,
738 #define section_hash_lookup(table, string, create, copy) \
739 ((struct section_hash_entry *) \
740 bfd_hash_lookup ((table), (string), (create), (copy)))
742 /* Initializes a new section. NEWSECT->NAME is already set. */
745 bfd_section_init (bfd *abfd, asection *newsect)
747 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */
749 newsect->id = section_id;
750 newsect->index = abfd->section_count;
751 newsect->owner = abfd;
753 /* Create a symbol whose only job is to point to this section. This
754 is useful for things like relocs which are relative to the base
756 newsect->symbol = bfd_make_empty_symbol (abfd);
757 if (newsect->symbol == NULL)
760 newsect->symbol->name = newsect->name;
761 newsect->symbol->value = 0;
762 newsect->symbol->section = newsect;
763 newsect->symbol->flags = BSF_SECTION_SYM;
765 newsect->symbol_ptr_ptr = &newsect->symbol;
767 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect)))
771 abfd->section_count++;
772 bfd_section_list_append (abfd, newsect);
779 section prototypes, , typedef asection, Sections
783 These are the functions exported by the section handling part of BFD.
788 bfd_section_list_clear
791 void bfd_section_list_clear (bfd *);
794 Clears the section list, and also resets the section count and
799 bfd_section_list_clear (bfd *abfd)
801 abfd->sections = NULL;
802 abfd->section_last = NULL;
803 abfd->section_count = 0;
804 memset (abfd->section_htab.table, 0,
805 abfd->section_htab.size * sizeof (struct bfd_hash_entry *));
810 bfd_get_section_by_name
813 asection *bfd_get_section_by_name (bfd *abfd, const char *name);
816 Run through @var{abfd} and return the one of the
817 <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
818 @xref{Sections}, for more information.
820 This should only be used in special cases; the normal way to process
821 all sections of a given name is to use <<bfd_map_over_sections>> and
822 <<strcmp>> on the name (or better yet, base it on the section flags
823 or something else) for each section.
827 bfd_get_section_by_name (bfd *abfd, const char *name)
829 struct section_hash_entry *sh;
831 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
840 bfd_get_section_by_name_if
843 asection *bfd_get_section_by_name_if
846 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),
850 Call the provided function @var{func} for each section
851 attached to the BFD @var{abfd} whose name matches @var{name},
852 passing @var{obj} as an argument. The function will be called
855 | func (abfd, the_section, obj);
857 It returns the first section for which @var{func} returns true,
863 bfd_get_section_by_name_if (bfd *abfd, const char *name,
864 bfd_boolean (*operation) (bfd *,
869 struct section_hash_entry *sh;
872 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
876 hash = sh->root.hash;
879 if ((*operation) (abfd, &sh->section, user_storage))
881 sh = (struct section_hash_entry *) sh->root.next;
883 while (sh != NULL && sh->root.hash == hash
884 && strcmp (sh->root.string, name) == 0);
891 bfd_get_unique_section_name
894 char *bfd_get_unique_section_name
895 (bfd *abfd, const char *templat, int *count);
898 Invent a section name that is unique in @var{abfd} by tacking
899 a dot and a digit suffix onto the original @var{templat}. If
900 @var{count} is non-NULL, then it specifies the first number
901 tried as a suffix to generate a unique name. The value
902 pointed to by @var{count} will be incremented in this case.
906 bfd_get_unique_section_name (bfd *abfd, const char *templat, int *count)
912 len = strlen (templat);
913 sname = bfd_malloc (len + 8);
916 memcpy (sname, templat, len);
923 /* If we have a million sections, something is badly wrong. */
926 sprintf (sname + len, ".%d", num++);
928 while (section_hash_lookup (&abfd->section_htab, sname, FALSE, FALSE));
937 bfd_make_section_old_way
940 asection *bfd_make_section_old_way (bfd *abfd, const char *name);
943 Create a new empty section called @var{name}
944 and attach it to the end of the chain of sections for the
945 BFD @var{abfd}. An attempt to create a section with a name which
946 is already in use returns its pointer without changing the
949 It has the funny name since this is the way it used to be
950 before it was rewritten....
953 o <<bfd_error_invalid_operation>> -
954 If output has already started for this BFD.
955 o <<bfd_error_no_memory>> -
956 If memory allocation fails.
961 bfd_make_section_old_way (bfd *abfd, const char *name)
963 struct section_hash_entry *sh;
966 if (abfd->output_has_begun)
968 bfd_set_error (bfd_error_invalid_operation);
972 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
973 return bfd_abs_section_ptr;
975 if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
976 return bfd_com_section_ptr;
978 if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
979 return bfd_und_section_ptr;
981 if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
982 return bfd_ind_section_ptr;
984 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
988 newsect = &sh->section;
989 if (newsect->name != NULL)
991 /* Section already exists. */
995 newsect->name = name;
996 return bfd_section_init (abfd, newsect);
1001 bfd_make_section_anyway
1004 asection *bfd_make_section_anyway (bfd *abfd, const char *name);
1007 Create a new empty section called @var{name} and attach it to the end of
1008 the chain of sections for @var{abfd}. Create a new section even if there
1009 is already a section with that name.
1011 Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
1012 o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
1013 o <<bfd_error_no_memory>> - If memory allocation fails.
1017 bfd_make_section_anyway (bfd *abfd, const char *name)
1019 struct section_hash_entry *sh;
1022 if (abfd->output_has_begun)
1024 bfd_set_error (bfd_error_invalid_operation);
1028 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
1032 newsect = &sh->section;
1033 if (newsect->name != NULL)
1035 /* We are making a section of the same name. Put it in the
1036 section hash table. Even though we can't find it directly by a
1037 hash lookup, we'll be able to find the section by traversing
1038 sh->root.next quicker than looking at all the bfd sections. */
1039 struct section_hash_entry *new_sh;
1040 new_sh = (struct section_hash_entry *)
1041 bfd_section_hash_newfunc (NULL, &abfd->section_htab, name);
1045 new_sh->root = sh->root;
1046 sh->root.next = &new_sh->root;
1047 newsect = &new_sh->section;
1050 newsect->name = name;
1051 return bfd_section_init (abfd, newsect);
1059 asection *bfd_make_section (bfd *, const char *name);
1062 Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
1063 bfd_set_error ()) without changing the section chain if there is already a
1064 section named @var{name}. If there is an error, return <<NULL>> and set
1069 bfd_make_section (bfd *abfd, const char *name)
1071 struct section_hash_entry *sh;
1074 if (abfd->output_has_begun)
1076 bfd_set_error (bfd_error_invalid_operation);
1080 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0
1081 || strcmp (name, BFD_COM_SECTION_NAME) == 0
1082 || strcmp (name, BFD_UND_SECTION_NAME) == 0
1083 || strcmp (name, BFD_IND_SECTION_NAME) == 0)
1086 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
1090 newsect = &sh->section;
1091 if (newsect->name != NULL)
1093 /* Section already exists. */
1097 newsect->name = name;
1098 return bfd_section_init (abfd, newsect);
1103 bfd_set_section_flags
1106 bfd_boolean bfd_set_section_flags
1107 (bfd *abfd, asection *sec, flagword flags);
1110 Set the attributes of the section @var{sec} in the BFD
1111 @var{abfd} to the value @var{flags}. Return <<TRUE>> on success,
1112 <<FALSE>> on error. Possible error returns are:
1114 o <<bfd_error_invalid_operation>> -
1115 The section cannot have one or more of the attributes
1116 requested. For example, a .bss section in <<a.out>> may not
1117 have the <<SEC_HAS_CONTENTS>> field set.
1122 bfd_set_section_flags (bfd *abfd ATTRIBUTE_UNUSED,
1126 section->flags = flags;
1132 bfd_map_over_sections
1135 void bfd_map_over_sections
1137 void (*func) (bfd *abfd, asection *sect, void *obj),
1141 Call the provided function @var{func} for each section
1142 attached to the BFD @var{abfd}, passing @var{obj} as an
1143 argument. The function will be called as if by
1145 | func (abfd, the_section, obj);
1147 This is the preferred method for iterating over sections; an
1148 alternative would be to use a loop:
1151 | for (p = abfd->sections; p != NULL; p = p->next)
1152 | func (abfd, p, ...)
1157 bfd_map_over_sections (bfd *abfd,
1158 void (*operation) (bfd *, asection *, void *),
1164 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
1165 (*operation) (abfd, sect, user_storage);
1167 if (i != abfd->section_count) /* Debugging */
1173 bfd_sections_find_if
1176 asection *bfd_sections_find_if
1178 bfd_boolean (*operation) (bfd *abfd, asection *sect, void *obj),
1182 Call the provided function @var{operation} for each section
1183 attached to the BFD @var{abfd}, passing @var{obj} as an
1184 argument. The function will be called as if by
1186 | operation (abfd, the_section, obj);
1188 It returns the first section for which @var{operation} returns true.
1193 bfd_sections_find_if (bfd *abfd,
1194 bfd_boolean (*operation) (bfd *, asection *, void *),
1199 for (sect = abfd->sections; sect != NULL; sect = sect->next)
1200 if ((*operation) (abfd, sect, user_storage))
1208 bfd_set_section_size
1211 bfd_boolean bfd_set_section_size
1212 (bfd *abfd, asection *sec, bfd_size_type val);
1215 Set @var{sec} to the size @var{val}. If the operation is
1216 ok, then <<TRUE>> is returned, else <<FALSE>>.
1218 Possible error returns:
1219 o <<bfd_error_invalid_operation>> -
1220 Writing has started to the BFD, so setting the size is invalid.
1225 bfd_set_section_size (bfd *abfd, sec_ptr ptr, bfd_size_type val)
1227 /* Once you've started writing to any section you cannot create or change
1228 the size of any others. */
1230 if (abfd->output_has_begun)
1232 bfd_set_error (bfd_error_invalid_operation);
1242 bfd_set_section_contents
1245 bfd_boolean bfd_set_section_contents
1246 (bfd *abfd, asection *section, const void *data,
1247 file_ptr offset, bfd_size_type count);
1250 Sets the contents of the section @var{section} in BFD
1251 @var{abfd} to the data starting in memory at @var{data}. The
1252 data is written to the output section starting at offset
1253 @var{offset} for @var{count} octets.
1255 Normally <<TRUE>> is returned, else <<FALSE>>. Possible error
1257 o <<bfd_error_no_contents>> -
1258 The output section does not have the <<SEC_HAS_CONTENTS>>
1259 attribute, so nothing can be written to it.
1262 This routine is front end to the back end function
1263 <<_bfd_set_section_contents>>.
1268 bfd_set_section_contents (bfd *abfd,
1270 const void *location,
1272 bfd_size_type count)
1276 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
1278 bfd_set_error (bfd_error_no_contents);
1283 if ((bfd_size_type) offset > sz
1285 || offset + count > sz
1286 || count != (size_t) count)
1288 bfd_set_error (bfd_error_bad_value);
1292 switch (abfd->direction)
1294 case read_direction:
1296 bfd_set_error (bfd_error_invalid_operation);
1299 case write_direction:
1302 case both_direction:
1303 /* File is opened for update. `output_has_begun' some time ago when
1304 the file was created. Do not recompute sections sizes or alignments
1305 in _bfd_set_section_content. */
1306 abfd->output_has_begun = TRUE;
1310 /* Record a copy of the data in memory if desired. */
1311 if (section->contents
1312 && location != section->contents + offset)
1313 memcpy (section->contents + offset, location, (size_t) count);
1315 if (BFD_SEND (abfd, _bfd_set_section_contents,
1316 (abfd, section, location, offset, count)))
1318 abfd->output_has_begun = TRUE;
1327 bfd_get_section_contents
1330 bfd_boolean bfd_get_section_contents
1331 (bfd *abfd, asection *section, void *location, file_ptr offset,
1332 bfd_size_type count);
1335 Read data from @var{section} in BFD @var{abfd}
1336 into memory starting at @var{location}. The data is read at an
1337 offset of @var{offset} from the start of the input section,
1338 and is read for @var{count} bytes.
1340 If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
1341 flag set are requested or if the section does not have the
1342 <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
1343 with zeroes. If no errors occur, <<TRUE>> is returned, else
1348 bfd_get_section_contents (bfd *abfd,
1352 bfd_size_type count)
1356 if (section->flags & SEC_CONSTRUCTOR)
1358 memset (location, 0, (size_t) count);
1362 sz = section->rawsize ? section->rawsize : section->size;
1363 if ((bfd_size_type) offset > sz
1365 || offset + count > sz
1366 || count != (size_t) count)
1368 bfd_set_error (bfd_error_bad_value);
1376 if ((section->flags & SEC_HAS_CONTENTS) == 0)
1378 memset (location, 0, (size_t) count);
1382 if ((section->flags & SEC_IN_MEMORY) != 0)
1384 memcpy (location, section->contents + offset, (size_t) count);
1388 return BFD_SEND (abfd, _bfd_get_section_contents,
1389 (abfd, section, location, offset, count));
1394 bfd_malloc_and_get_section
1397 bfd_boolean bfd_malloc_and_get_section
1398 (bfd *abfd, asection *section, bfd_byte **buf);
1401 Read all data from @var{section} in BFD @var{abfd}
1402 into a buffer, *@var{buf}, malloc'd by this function.
1406 bfd_malloc_and_get_section (bfd *abfd, sec_ptr sec, bfd_byte **buf)
1408 bfd_size_type sz = sec->rawsize ? sec->rawsize : sec->size;
1415 p = bfd_malloc (sec->rawsize > sec->size ? sec->rawsize : sec->size);
1420 return bfd_get_section_contents (abfd, sec, p, 0, sz);
1424 bfd_copy_private_section_data
1427 bfd_boolean bfd_copy_private_section_data
1428 (bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
1431 Copy private section information from @var{isec} in the BFD
1432 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1433 Return <<TRUE>> on success, <<FALSE>> on error. Possible error
1436 o <<bfd_error_no_memory>> -
1437 Not enough memory exists to create private data for @var{osec}.
1439 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1440 . BFD_SEND (obfd, _bfd_copy_private_section_data, \
1441 . (ibfd, isection, obfd, osection))
1446 _bfd_strip_section_from_output
1449 void _bfd_strip_section_from_output
1450 (struct bfd_link_info *info, asection *section);
1453 Remove @var{section} from the output. If the output section
1454 becomes empty, remove it from the output bfd.
1456 This function won't actually do anything except twiddle flags
1457 if called too late in the linking process, when it's not safe
1461 _bfd_strip_section_from_output (struct bfd_link_info *info, asection *s)
1467 s->flags |= SEC_EXCLUDE;
1469 /* If the section wasn't assigned to an output section, or the
1470 section has been discarded by the linker script, there's nothing
1472 os = s->output_section;
1473 if (os == NULL || os->owner == NULL)
1476 /* If the output section has other (non-excluded) input sections, we
1478 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
1479 for (is = abfd->sections; is != NULL; is = is->next)
1480 if (is->output_section == os && (is->flags & SEC_EXCLUDE) == 0)
1483 /* If the output section is empty, flag it for removal too.
1484 See ldlang.c:strip_excluded_output_sections for the action. */
1485 os->flags |= SEC_EXCLUDE;
1490 bfd_generic_is_group_section
1493 bfd_boolean bfd_generic_is_group_section (bfd *, const asection *sec);
1496 Returns TRUE if @var{sec} is a member of a group.
1500 bfd_generic_is_group_section (bfd *abfd ATTRIBUTE_UNUSED,
1501 const asection *sec ATTRIBUTE_UNUSED)
1508 bfd_generic_discard_group
1511 bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group);
1514 Remove all members of @var{group} from the output.
1518 bfd_generic_discard_group (bfd *abfd ATTRIBUTE_UNUSED,
1519 asection *group ATTRIBUTE_UNUSED)