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 .{* 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. *}
169 .typedef struct bfd_section
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. *}
182 . struct bfd_section *next;
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 . {* A mark flag used by some of the linker backends. *}
368 . unsigned int linker_mark : 1;
370 . {* Another mark flag used by some of the linker backends. Set for
371 . output sections that have an input section. *}
372 . unsigned int linker_has_input : 1;
374 . {* A mark flag used by some linker backends for garbage collection. *}
375 . unsigned int gc_mark : 1;
377 . {* The following flags are used by the ELF linker. *}
379 . {* Mark sections which have been allocated to segments. *}
380 . unsigned int segment_mark : 1;
382 . {* Type of sec_info information. *}
383 . unsigned int sec_info_type:3;
384 .#define ELF_INFO_TYPE_NONE 0
385 .#define ELF_INFO_TYPE_STABS 1
386 .#define ELF_INFO_TYPE_MERGE 2
387 .#define ELF_INFO_TYPE_EH_FRAME 3
388 .#define ELF_INFO_TYPE_JUST_SYMS 4
390 . {* Nonzero if this section uses RELA relocations, rather than REL. *}
391 . unsigned int use_rela_p:1;
393 . {* Bits used by various backends. *}
395 . {* Nonzero if this section has TLS related relocations. *}
396 . unsigned int has_tls_reloc:1;
398 . {* Nonzero if this section has a gp reloc. *}
399 . unsigned int has_gp_reloc:1;
401 . {* Nonzero if this section needs the relax finalize pass. *}
402 . unsigned int need_finalize_relax:1;
404 . {* Whether relocations have been processed. *}
405 . unsigned int reloc_done : 1;
407 . {* End of internal packed boolean fields. *}
409 . {* The virtual memory address of the section - where it will be
410 . at run time. The symbols are relocated against this. The
411 . user_set_vma flag is maintained by bfd; if it's not set, the
412 . backend can assign addresses (for example, in <<a.out>>, where
413 . the default address for <<.data>> is dependent on the specific
414 . target and various flags). *}
417 . {* The load address of the section - where it would be in a
418 . rom image; really only used for writing section header
422 . {* The size of the section in octets, as it will be output.
423 . Contains a value even if the section has no contents (e.g., the
424 . size of <<.bss>>). *}
425 . bfd_size_type size;
427 . {* For input sections, the original size on disk of the section, in
428 . octets. This field is used by the linker relaxation code. It is
429 . currently only set for sections where the linker relaxation scheme
430 . doesn't cache altered section and reloc contents (stabs, eh_frame,
431 . SEC_MERGE, some coff relaxing targets), and thus the original size
432 . needs to be kept to read the section multiple times.
433 . For output sections, rawsize holds the section size calculated on
434 . a previous linker relaxation pass. *}
435 . bfd_size_type rawsize;
437 . {* If this section is going to be output, then this value is the
438 . offset in *bytes* into the output section of the first byte in the
439 . input section (byte ==> smallest addressable unit on the
440 . target). In most cases, if this was going to start at the
441 . 100th octet (8-bit quantity) in the output section, this value
442 . would be 100. However, if the target byte size is 16 bits
443 . (bfd_octets_per_byte is "2"), this value would be 50. *}
444 . bfd_vma output_offset;
446 . {* The output section through which to map on output. *}
447 . struct bfd_section *output_section;
449 . {* The alignment requirement of the section, as an exponent of 2 -
450 . e.g., 3 aligns to 2^3 (or 8). *}
451 . unsigned int alignment_power;
453 . {* If an input section, a pointer to a vector of relocation
454 . records for the data in this section. *}
455 . struct reloc_cache_entry *relocation;
457 . {* If an output section, a pointer to a vector of pointers to
458 . relocation records for the data in this section. *}
459 . struct reloc_cache_entry **orelocation;
461 . {* The number of relocation records in one of the above. *}
462 . unsigned reloc_count;
464 . {* Information below is back end specific - and not always used
467 . {* File position of section data. *}
470 . {* File position of relocation info. *}
471 . file_ptr rel_filepos;
473 . {* File position of line data. *}
474 . file_ptr line_filepos;
476 . {* Pointer to data for applications. *}
479 . {* If the SEC_IN_MEMORY flag is set, this points to the actual
481 . unsigned char *contents;
483 . {* Attached line number information. *}
486 . {* Number of line number records. *}
487 . unsigned int lineno_count;
489 . {* Entity size for merging purposes. *}
490 . unsigned int entsize;
492 . {* Optional information about a COMDAT entry; NULL if not COMDAT. *}
493 . struct bfd_comdat_info *comdat;
495 . {* Points to the kept section if this section is a link-once section,
496 . and is discarded. *}
497 . struct bfd_section *kept_section;
499 . {* When a section is being output, this value changes as more
500 . linenumbers are written out. *}
501 . file_ptr moving_line_filepos;
503 . {* What the section number is in the target world. *}
508 . {* If this is a constructor section then here is a list of the
509 . relocations created to relocate items within it. *}
510 . struct relent_chain *constructor_chain;
512 . {* The BFD which owns the section. *}
515 . {* A symbol which points at this section only. *}
516 . struct bfd_symbol *symbol;
517 . struct bfd_symbol **symbol_ptr_ptr;
519 . struct bfd_link_order *link_order_head;
520 . struct bfd_link_order *link_order_tail;
523 .{* These sections are global, and are managed by BFD. The application
524 . and target back end are not permitted to change the values in
525 . these sections. New code should use the section_ptr macros rather
526 . than referring directly to the const sections. The const sections
527 . may eventually vanish. *}
528 .#define BFD_ABS_SECTION_NAME "*ABS*"
529 .#define BFD_UND_SECTION_NAME "*UND*"
530 .#define BFD_COM_SECTION_NAME "*COM*"
531 .#define BFD_IND_SECTION_NAME "*IND*"
533 .{* The absolute section. *}
534 .extern asection bfd_abs_section;
535 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
536 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
537 .{* Pointer to the undefined section. *}
538 .extern asection bfd_und_section;
539 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
540 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
541 .{* Pointer to the common section. *}
542 .extern asection bfd_com_section;
543 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
544 .{* Pointer to the indirect section. *}
545 .extern asection bfd_ind_section;
546 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
547 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
549 .#define bfd_is_const_section(SEC) \
550 . ( ((SEC) == bfd_abs_section_ptr) \
551 . || ((SEC) == bfd_und_section_ptr) \
552 . || ((SEC) == bfd_com_section_ptr) \
553 . || ((SEC) == bfd_ind_section_ptr))
555 .extern const struct bfd_symbol * const bfd_abs_symbol;
556 .extern const struct bfd_symbol * const bfd_com_symbol;
557 .extern const struct bfd_symbol * const bfd_und_symbol;
558 .extern const struct bfd_symbol * const bfd_ind_symbol;
560 .{* Macros to handle insertion and deletion of a bfd's sections. These
561 . only handle the list pointers, ie. do not adjust section_count,
562 . target_index etc. *}
563 .#define bfd_section_list_remove(ABFD, PS) \
566 . asection **_ps = PS; \
567 . asection *_s = *_ps; \
569 . if (_s->next == NULL) \
570 . (ABFD)->section_tail = _ps; \
573 .#define bfd_section_list_insert(ABFD, PS, S) \
576 . asection **_ps = PS; \
577 . asection *_s = S; \
580 . if (_s->next == NULL) \
581 . (ABFD)->section_tail = &_s->next; \
587 /* We use a macro to initialize the static asymbol structures because
588 traditional C does not permit us to initialize a union member while
589 gcc warns if we don't initialize it. */
590 /* the_bfd, name, value, attr, section [, udata] */
592 #define GLOBAL_SYM_INIT(NAME, SECTION) \
593 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION, { 0 }}
595 #define GLOBAL_SYM_INIT(NAME, SECTION) \
596 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION }
599 /* These symbols are global, not specific to any BFD. Therefore, anything
600 that tries to change them is broken, and should be repaired. */
602 static const asymbol global_syms[] =
604 GLOBAL_SYM_INIT (BFD_COM_SECTION_NAME, &bfd_com_section),
605 GLOBAL_SYM_INIT (BFD_UND_SECTION_NAME, &bfd_und_section),
606 GLOBAL_SYM_INIT (BFD_ABS_SECTION_NAME, &bfd_abs_section),
607 GLOBAL_SYM_INIT (BFD_IND_SECTION_NAME, &bfd_ind_section)
610 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
611 const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
613 /* name, id, index, next, flags, user_set_vma, */ \
614 { NAME, IDX, 0, NULL, FLAGS, 0, \
616 /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \
619 /* sec_info_type, use_rela_p, has_tls_reloc, has_gp_reloc, */ \
622 /* need_finalize_relax, reloc_done, */ \
625 /* vma, lma, size, rawsize */ \
628 /* output_offset, output_section, alignment_power, */ \
629 0, (struct bfd_section *) &SEC, 0, \
631 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
632 NULL, NULL, 0, 0, 0, \
634 /* line_filepos, userdata, contents, lineno, lineno_count, */ \
635 0, NULL, NULL, NULL, 0, \
637 /* entsize, comdat, kept_section, moving_line_filepos, */ \
640 /* target_index, used_by_bfd, constructor_chain, owner, */ \
641 0, NULL, NULL, NULL, \
644 (struct bfd_symbol *) &global_syms[IDX], \
646 /* symbol_ptr_ptr, */ \
647 (struct bfd_symbol **) &SYM, \
649 /* link_order_head, link_order_tail */ \
653 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
654 BFD_COM_SECTION_NAME, 0);
655 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
656 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
657 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
660 struct section_hash_entry
662 struct bfd_hash_entry root;
666 /* Initialize an entry in the section hash table. */
668 struct bfd_hash_entry *
669 bfd_section_hash_newfunc (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);
686 memset (&((struct section_hash_entry *) entry)->section, 0,
692 #define section_hash_lookup(table, string, create, copy) \
693 ((struct section_hash_entry *) \
694 bfd_hash_lookup ((table), (string), (create), (copy)))
696 /* Initializes a new section. NEWSECT->NAME is already set. */
699 bfd_section_init (bfd *abfd, asection *newsect)
701 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */
703 newsect->id = section_id;
704 newsect->index = abfd->section_count;
705 newsect->owner = abfd;
707 /* Create a symbol whose only job is to point to this section. This
708 is useful for things like relocs which are relative to the base
710 newsect->symbol = bfd_make_empty_symbol (abfd);
711 if (newsect->symbol == NULL)
714 newsect->symbol->name = newsect->name;
715 newsect->symbol->value = 0;
716 newsect->symbol->section = newsect;
717 newsect->symbol->flags = BSF_SECTION_SYM;
719 newsect->symbol_ptr_ptr = &newsect->symbol;
721 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect)))
725 abfd->section_count++;
726 *abfd->section_tail = newsect;
727 abfd->section_tail = &newsect->next;
734 section prototypes, , typedef asection, Sections
738 These are the functions exported by the section handling part of BFD.
743 bfd_section_list_clear
746 void bfd_section_list_clear (bfd *);
749 Clears the section list, and also resets the section count and
754 bfd_section_list_clear (bfd *abfd)
756 abfd->sections = NULL;
757 abfd->section_tail = &abfd->sections;
758 abfd->section_count = 0;
759 memset (abfd->section_htab.table, 0,
760 abfd->section_htab.size * sizeof (struct bfd_hash_entry *));
765 bfd_get_section_by_name
768 asection *bfd_get_section_by_name (bfd *abfd, const char *name);
771 Run through @var{abfd} and return the one of the
772 <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
773 @xref{Sections}, for more information.
775 This should only be used in special cases; the normal way to process
776 all sections of a given name is to use <<bfd_map_over_sections>> and
777 <<strcmp>> on the name (or better yet, base it on the section flags
778 or something else) for each section.
782 bfd_get_section_by_name (bfd *abfd, const char *name)
784 struct section_hash_entry *sh;
786 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
795 bfd_get_section_by_name_if
798 asection *bfd_get_section_by_name_if
801 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),
805 Call the provided function @var{func} for each section
806 attached to the BFD @var{abfd} whose name matches @var{name},
807 passing @var{obj} as an argument. The function will be called
810 | func (abfd, the_section, obj);
812 It returns the first section for which @var{func} returns true,
818 bfd_get_section_by_name_if (bfd *abfd, const char *name,
819 bfd_boolean (*operation) (bfd *,
824 struct section_hash_entry *sh;
827 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
831 hash = sh->root.hash;
834 if ((*operation) (abfd, &sh->section, user_storage))
836 sh = (struct section_hash_entry *) sh->root.next;
838 while (sh != NULL && sh->root.hash == hash
839 && strcmp (sh->root.string, name) == 0);
846 bfd_get_unique_section_name
849 char *bfd_get_unique_section_name
850 (bfd *abfd, const char *templat, int *count);
853 Invent a section name that is unique in @var{abfd} by tacking
854 a dot and a digit suffix onto the original @var{templat}. If
855 @var{count} is non-NULL, then it specifies the first number
856 tried as a suffix to generate a unique name. The value
857 pointed to by @var{count} will be incremented in this case.
861 bfd_get_unique_section_name (bfd *abfd, const char *templat, int *count)
867 len = strlen (templat);
868 sname = bfd_malloc (len + 8);
871 memcpy (sname, templat, len);
878 /* If we have a million sections, something is badly wrong. */
881 sprintf (sname + len, ".%d", num++);
883 while (section_hash_lookup (&abfd->section_htab, sname, FALSE, FALSE));
892 bfd_make_section_old_way
895 asection *bfd_make_section_old_way (bfd *abfd, const char *name);
898 Create a new empty section called @var{name}
899 and attach it to the end of the chain of sections for the
900 BFD @var{abfd}. An attempt to create a section with a name which
901 is already in use returns its pointer without changing the
904 It has the funny name since this is the way it used to be
905 before it was rewritten....
908 o <<bfd_error_invalid_operation>> -
909 If output has already started for this BFD.
910 o <<bfd_error_no_memory>> -
911 If memory allocation fails.
916 bfd_make_section_old_way (bfd *abfd, const char *name)
918 struct section_hash_entry *sh;
921 if (abfd->output_has_begun)
923 bfd_set_error (bfd_error_invalid_operation);
927 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
928 return bfd_abs_section_ptr;
930 if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
931 return bfd_com_section_ptr;
933 if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
934 return bfd_und_section_ptr;
936 if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
937 return bfd_ind_section_ptr;
939 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
943 newsect = &sh->section;
944 if (newsect->name != NULL)
946 /* Section already exists. */
950 newsect->name = name;
951 return bfd_section_init (abfd, newsect);
956 bfd_make_section_anyway
959 asection *bfd_make_section_anyway (bfd *abfd, const char *name);
962 Create a new empty section called @var{name} and attach it to the end of
963 the chain of sections for @var{abfd}. Create a new section even if there
964 is already a section with that name.
966 Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
967 o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
968 o <<bfd_error_no_memory>> - If memory allocation fails.
972 bfd_make_section_anyway (bfd *abfd, const char *name)
974 struct section_hash_entry *sh;
977 if (abfd->output_has_begun)
979 bfd_set_error (bfd_error_invalid_operation);
983 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
987 newsect = &sh->section;
988 if (newsect->name != NULL)
990 /* We are making a section of the same name. Put it in the
991 section hash table. Even though we can't find it directly by a
992 hash lookup, we'll be able to find the section by traversing
993 sh->root.next quicker than looking at all the bfd sections. */
994 struct section_hash_entry *new_sh;
995 new_sh = (struct section_hash_entry *)
996 bfd_section_hash_newfunc (NULL, &abfd->section_htab, name);
1000 new_sh->root = sh->root;
1001 sh->root.next = &new_sh->root;
1002 newsect = &new_sh->section;
1005 newsect->name = name;
1006 return bfd_section_init (abfd, newsect);
1014 asection *bfd_make_section (bfd *, const char *name);
1017 Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
1018 bfd_set_error ()) without changing the section chain if there is already a
1019 section named @var{name}. If there is an error, return <<NULL>> and set
1024 bfd_make_section (bfd *abfd, const char *name)
1026 struct section_hash_entry *sh;
1029 if (abfd->output_has_begun)
1031 bfd_set_error (bfd_error_invalid_operation);
1035 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0
1036 || strcmp (name, BFD_COM_SECTION_NAME) == 0
1037 || strcmp (name, BFD_UND_SECTION_NAME) == 0
1038 || strcmp (name, BFD_IND_SECTION_NAME) == 0)
1041 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
1045 newsect = &sh->section;
1046 if (newsect->name != NULL)
1048 /* Section already exists. */
1052 newsect->name = name;
1053 return bfd_section_init (abfd, newsect);
1058 bfd_set_section_flags
1061 bfd_boolean bfd_set_section_flags
1062 (bfd *abfd, asection *sec, flagword flags);
1065 Set the attributes of the section @var{sec} in the BFD
1066 @var{abfd} to the value @var{flags}. Return <<TRUE>> on success,
1067 <<FALSE>> on error. Possible error returns are:
1069 o <<bfd_error_invalid_operation>> -
1070 The section cannot have one or more of the attributes
1071 requested. For example, a .bss section in <<a.out>> may not
1072 have the <<SEC_HAS_CONTENTS>> field set.
1077 bfd_set_section_flags (bfd *abfd ATTRIBUTE_UNUSED,
1082 /* If you try to copy a text section from an input file (where it
1083 has the SEC_CODE flag set) to an output file, this loses big if
1084 the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
1085 set - which it doesn't, at least not for a.out. FIXME */
1087 if ((flags & bfd_applicable_section_flags (abfd)) != flags)
1089 bfd_set_error (bfd_error_invalid_operation);
1094 section->flags = flags;
1100 bfd_map_over_sections
1103 void bfd_map_over_sections
1105 void (*func) (bfd *abfd, asection *sect, void *obj),
1109 Call the provided function @var{func} for each section
1110 attached to the BFD @var{abfd}, passing @var{obj} as an
1111 argument. The function will be called as if by
1113 | func (abfd, the_section, obj);
1115 This is the preferred method for iterating over sections; an
1116 alternative would be to use a loop:
1119 | for (p = abfd->sections; p != NULL; p = p->next)
1120 | func (abfd, p, ...)
1125 bfd_map_over_sections (bfd *abfd,
1126 void (*operation) (bfd *, asection *, void *),
1132 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
1133 (*operation) (abfd, sect, user_storage);
1135 if (i != abfd->section_count) /* Debugging */
1141 bfd_sections_find_if
1144 asection *bfd_sections_find_if
1146 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),
1150 Call the provided function @var{func} for each section
1151 attached to the BFD @var{abfd}, passing @var{obj} as an
1152 argument. The function will be called as if by
1154 | func (abfd, the_section, obj);
1156 It returns the first section for which @var{func} returns true.
1161 bfd_sections_find_if (bfd *abfd,
1162 bfd_boolean (*operation) (bfd *, asection *, void *),
1167 for (sect = abfd->sections; sect != NULL; sect = sect->next)
1168 if ((*operation) (abfd, sect, user_storage))
1176 bfd_set_section_size
1179 bfd_boolean bfd_set_section_size
1180 (bfd *abfd, asection *sec, bfd_size_type val);
1183 Set @var{sec} to the size @var{val}. If the operation is
1184 ok, then <<TRUE>> is returned, else <<FALSE>>.
1186 Possible error returns:
1187 o <<bfd_error_invalid_operation>> -
1188 Writing has started to the BFD, so setting the size is invalid.
1193 bfd_set_section_size (bfd *abfd, sec_ptr ptr, bfd_size_type val)
1195 /* Once you've started writing to any section you cannot create or change
1196 the size of any others. */
1198 if (abfd->output_has_begun)
1200 bfd_set_error (bfd_error_invalid_operation);
1210 bfd_set_section_contents
1213 bfd_boolean bfd_set_section_contents
1214 (bfd *abfd, asection *section, const void *data,
1215 file_ptr offset, bfd_size_type count);
1218 Sets the contents of the section @var{section} in BFD
1219 @var{abfd} to the data starting in memory at @var{data}. The
1220 data is written to the output section starting at offset
1221 @var{offset} for @var{count} octets.
1223 Normally <<TRUE>> is returned, else <<FALSE>>. Possible error
1225 o <<bfd_error_no_contents>> -
1226 The output section does not have the <<SEC_HAS_CONTENTS>>
1227 attribute, so nothing can be written to it.
1230 This routine is front end to the back end function
1231 <<_bfd_set_section_contents>>.
1236 bfd_set_section_contents (bfd *abfd,
1238 const void *location,
1240 bfd_size_type count)
1244 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
1246 bfd_set_error (bfd_error_no_contents);
1251 if ((bfd_size_type) offset > sz
1253 || offset + count > sz
1254 || count != (size_t) count)
1256 bfd_set_error (bfd_error_bad_value);
1260 switch (abfd->direction)
1262 case read_direction:
1264 bfd_set_error (bfd_error_invalid_operation);
1267 case write_direction:
1270 case both_direction:
1271 /* File is opened for update. `output_has_begun' some time ago when
1272 the file was created. Do not recompute sections sizes or alignments
1273 in _bfd_set_section_content. */
1274 abfd->output_has_begun = TRUE;
1278 /* Record a copy of the data in memory if desired. */
1279 if (section->contents
1280 && location != section->contents + offset)
1281 memcpy (section->contents + offset, location, (size_t) count);
1283 if (BFD_SEND (abfd, _bfd_set_section_contents,
1284 (abfd, section, location, offset, count)))
1286 abfd->output_has_begun = TRUE;
1295 bfd_get_section_contents
1298 bfd_boolean bfd_get_section_contents
1299 (bfd *abfd, asection *section, void *location, file_ptr offset,
1300 bfd_size_type count);
1303 Read data from @var{section} in BFD @var{abfd}
1304 into memory starting at @var{location}. The data is read at an
1305 offset of @var{offset} from the start of the input section,
1306 and is read for @var{count} bytes.
1308 If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
1309 flag set are requested or if the section does not have the
1310 <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
1311 with zeroes. If no errors occur, <<TRUE>> is returned, else
1316 bfd_get_section_contents (bfd *abfd,
1320 bfd_size_type count)
1324 if (section->flags & SEC_CONSTRUCTOR)
1326 memset (location, 0, (size_t) count);
1330 sz = section->rawsize ? section->rawsize : section->size;
1331 if ((bfd_size_type) offset > sz
1333 || offset + count > sz
1334 || count != (size_t) count)
1336 bfd_set_error (bfd_error_bad_value);
1344 if ((section->flags & SEC_HAS_CONTENTS) == 0)
1346 memset (location, 0, (size_t) count);
1350 if ((section->flags & SEC_IN_MEMORY) != 0)
1352 memcpy (location, section->contents + offset, (size_t) count);
1356 return BFD_SEND (abfd, _bfd_get_section_contents,
1357 (abfd, section, location, offset, count));
1362 bfd_malloc_and_get_section
1365 bfd_boolean bfd_malloc_and_get_section
1366 (bfd *abfd, asection *section, bfd_byte **buf);
1369 Read all data from @var{section} in BFD @var{abfd}
1370 into a buffer, *@var{buf}, malloc'd by this function.
1374 bfd_malloc_and_get_section (bfd *abfd, sec_ptr sec, bfd_byte **buf)
1376 bfd_size_type sz = sec->rawsize ? sec->rawsize : sec->size;
1383 p = bfd_malloc (sec->rawsize > sec->size ? sec->rawsize : sec->size);
1388 return bfd_get_section_contents (abfd, sec, p, 0, sz);
1392 bfd_copy_private_section_data
1395 bfd_boolean bfd_copy_private_section_data
1396 (bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
1399 Copy private section information from @var{isec} in the BFD
1400 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1401 Return <<TRUE>> on success, <<FALSE>> on error. Possible error
1404 o <<bfd_error_no_memory>> -
1405 Not enough memory exists to create private data for @var{osec}.
1407 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1408 . BFD_SEND (obfd, _bfd_copy_private_section_data, \
1409 . (ibfd, isection, obfd, osection))
1414 _bfd_strip_section_from_output
1417 void _bfd_strip_section_from_output
1418 (struct bfd_link_info *info, asection *section);
1421 Remove @var{section} from the output. If the output section
1422 becomes empty, remove it from the output bfd.
1424 This function won't actually do anything except twiddle flags
1425 if called too late in the linking process, when it's not safe
1429 _bfd_strip_section_from_output (struct bfd_link_info *info, asection *s)
1435 s->flags |= SEC_EXCLUDE;
1437 /* If the section wasn't assigned to an output section, or the
1438 section has been discarded by the linker script, there's nothing
1440 os = s->output_section;
1441 if (os == NULL || os->owner == NULL)
1444 /* If the output section has other (non-excluded) input sections, we
1446 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
1447 for (is = abfd->sections; is != NULL; is = is->next)
1448 if (is->output_section == os && (is->flags & SEC_EXCLUDE) == 0)
1451 /* If the output section is empty, flag it for removal too.
1452 See ldlang.c:strip_excluded_output_sections for the action. */
1453 os->flags |= SEC_EXCLUDE;
1458 bfd_generic_is_group_section
1461 bfd_boolean bfd_generic_is_group_section (bfd *, const asection *sec);
1464 Returns TRUE if @var{sec} is a member of a group.
1468 bfd_generic_is_group_section (bfd *abfd ATTRIBUTE_UNUSED,
1469 const asection *sec ATTRIBUTE_UNUSED)
1476 bfd_generic_discard_group
1479 bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group);
1482 Remove all members of @var{group} from the output.
1486 bfd_generic_discard_group (bfd *abfd ATTRIBUTE_UNUSED,
1487 asection *group ATTRIBUTE_UNUSED)