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1 @section Sections
2 The raw data contained within a BFD is maintained through the
3 section abstraction. A single BFD may have any number of
4 sections. It keeps hold of them by pointing to the first;
5 each one points to the next in the list.
7 Sections are supported in BFD in @code{section.c}.
9 @menu
10 * Section Input::
11 * Section Output::
12 * typedef asection::
13 * section prototypes::
14 @end menu
16 @node Section Input, Section Output, Sections, Sections
17 @subsection Section input
18 When a BFD is opened for reading, the section structures are
19 created and attached to the BFD.
21 Each section has a name which describes the section in the
22 outside world---for example, @code{a.out} would contain at least
23 three sections, called @code{.text}, @code{.data} and @code{.bss}.
25 Names need not be unique; for example a COFF file may have several
26 sections named @code{.data}.
28 Sometimes a BFD will contain more than the ``natural'' number of
29 sections. A back end may attach other sections containing
30 constructor data, or an application may add a section (using
31 @code{bfd_make_section}) to the sections attached to an already open
32 BFD. For example, the linker creates an extra section
33 @code{COMMON} for each input file's BFD to hold information about
34 common storage.
36 The raw data is not necessarily read in when
37 the section descriptor is created. Some targets may leave the
38 data in place until a @code{bfd_get_section_contents} call is
39 made. Other back ends may read in all the data at once. For
40 example, an S-record file has to be read once to determine the
41 size of the data. An IEEE-695 file doesn't contain raw data in
42 sections, but data and relocation expressions intermixed, so
43 the data area has to be parsed to get out the data and
44 relocations.
46 @node Section Output, typedef asection, Section Input, Sections
47 @subsection Section output
48 To write a new object style BFD, the various sections to be
49 written have to be created. They are attached to the BFD in
50 the same way as input sections; data is written to the
51 sections using @code{bfd_set_section_contents}.
53 Any program that creates or combines sections (e.g., the assembler
54 and linker) must use the @code{asection} fields @code{output_section} and
55 @code{output_offset} to indicate the file sections to which each
56 section must be written. (If the section is being created from
57 scratch, @code{output_section} should probably point to the section
58 itself and @code{output_offset} should probably be zero.)
60 The data to be written comes from input sections attached
61 (via @code{output_section} pointers) to
62 the output sections. The output section structure can be
63 considered a filter for the input section: the output section
64 determines the vma of the output data and the name, but the
65 input section determines the offset into the output section of
66 the data to be written.
68 E.g., to create a section "O", starting at 0x100, 0x123 long,
69 containing two subsections, "A" at offset 0x0 (i.e., at vma
70 0x100) and "B" at offset 0x20 (i.e., at vma 0x120) the @code{asection}
71 structures would look like:
73 @example
74 section name "A"
75 output_offset 0x00
76 size 0x20
77 output_section -----------> section name "O"
78 | vma 0x100
79 section name "B" | size 0x123
80 output_offset 0x20 |
81 size 0x103 |
82 output_section --------|
83 @end example
85 @subsection Link orders
86 The data within a section is stored in a @dfn{link_order}.
87 These are much like the fixups in @code{gas}. The link_order
88 abstraction allows a section to grow and shrink within itself.
90 A link_order knows how big it is, and which is the next
91 link_order and where the raw data for it is; it also points to
92 a list of relocations which apply to it.
94 The link_order is used by the linker to perform relaxing on
95 final code. The compiler creates code which is as big as
96 necessary to make it work without relaxing, and the user can
97 select whether to relax. Sometimes relaxing takes a lot of
98 time. The linker runs around the relocations to see if any
99 are attached to data which can be shrunk, if so it does it on
100 a link_order by link_order basis.
103 @node typedef asection, section prototypes, Section Output, Sections
104 @subsection typedef asection
105 Here is the section structure:
108 @example
110 typedef struct bfd_section
111 @{
112 /* The name of the section; the name isn't a copy, the pointer is
113 the same as that passed to bfd_make_section. */
114 const char *name;
116 /* A unique sequence number. */
117 int id;
119 /* Which section in the bfd; 0..n-1 as sections are created in a bfd. */
120 int index;
122 /* The next section in the list belonging to the BFD, or NULL. */
123 struct bfd_section *next;
125 /* The previous section in the list belonging to the BFD, or NULL. */
126 struct bfd_section *prev;
128 /* The field flags contains attributes of the section. Some
129 flags are read in from the object file, and some are
130 synthesized from other information. */
131 flagword flags;
133 #define SEC_NO_FLAGS 0x000
135 /* Tells the OS to allocate space for this section when loading.
136 This is clear for a section containing debug information only. */
137 #define SEC_ALLOC 0x001
139 /* Tells the OS to load the section from the file when loading.
140 This is clear for a .bss section. */
141 #define SEC_LOAD 0x002
143 /* The section contains data still to be relocated, so there is
144 some relocation information too. */
145 #define SEC_RELOC 0x004
147 /* A signal to the OS that the section contains read only data. */
148 #define SEC_READONLY 0x008
150 /* The section contains code only. */
151 #define SEC_CODE 0x010
153 /* The section contains data only. */
154 #define SEC_DATA 0x020
156 /* The section will reside in ROM. */
157 #define SEC_ROM 0x040
159 /* The section contains constructor information. This section
160 type is used by the linker to create lists of constructors and
161 destructors used by @code{g++}. When a back end sees a symbol
162 which should be used in a constructor list, it creates a new
163 section for the type of name (e.g., @code{__CTOR_LIST__}), attaches
164 the symbol to it, and builds a relocation. To build the lists
165 of constructors, all the linker has to do is catenate all the
166 sections called @code{__CTOR_LIST__} and relocate the data
167 contained within - exactly the operations it would peform on
168 standard data. */
169 #define SEC_CONSTRUCTOR 0x080
171 /* The section has contents - a data section could be
172 @code{SEC_ALLOC} | @code{SEC_HAS_CONTENTS}; a debug section could be
173 @code{SEC_HAS_CONTENTS} */
174 #define SEC_HAS_CONTENTS 0x100
176 /* An instruction to the linker to not output the section
177 even if it has information which would normally be written. */
178 #define SEC_NEVER_LOAD 0x200
180 /* The section contains thread local data. */
181 #define SEC_THREAD_LOCAL 0x400
183 /* The section has GOT references. This flag is only for the
184 linker, and is currently only used by the elf32-hppa back end.
185 It will be set if global offset table references were detected
186 in this section, which indicate to the linker that the section
187 contains PIC code, and must be handled specially when doing a
188 static link. */
189 #define SEC_HAS_GOT_REF 0x800
191 /* The section contains common symbols (symbols may be defined
192 multiple times, the value of a symbol is the amount of
193 space it requires, and the largest symbol value is the one
194 used). Most targets have exactly one of these (which we
195 translate to bfd_com_section_ptr), but ECOFF has two. */
196 #define SEC_IS_COMMON 0x1000
198 /* The section contains only debugging information. For
199 example, this is set for ELF .debug and .stab sections.
200 strip tests this flag to see if a section can be
201 discarded. */
202 #define SEC_DEBUGGING 0x2000
204 /* The contents of this section are held in memory pointed to
205 by the contents field. This is checked by bfd_get_section_contents,
206 and the data is retrieved from memory if appropriate. */
207 #define SEC_IN_MEMORY 0x4000
209 /* The contents of this section are to be excluded by the
210 linker for executable and shared objects unless those
211 objects are to be further relocated. */
212 #define SEC_EXCLUDE 0x8000
214 /* The contents of this section are to be sorted based on the sum of
215 the symbol and addend values specified by the associated relocation
216 entries. Entries without associated relocation entries will be
217 appended to the end of the section in an unspecified order. */
218 #define SEC_SORT_ENTRIES 0x10000
220 /* When linking, duplicate sections of the same name should be
221 discarded, rather than being combined into a single section as
222 is usually done. This is similar to how common symbols are
223 handled. See SEC_LINK_DUPLICATES below. */
224 #define SEC_LINK_ONCE 0x20000
226 /* If SEC_LINK_ONCE is set, this bitfield describes how the linker
227 should handle duplicate sections. */
228 #define SEC_LINK_DUPLICATES 0x40000
230 /* This value for SEC_LINK_DUPLICATES means that duplicate
231 sections with the same name should simply be discarded. */
232 #define SEC_LINK_DUPLICATES_DISCARD 0x0
234 /* This value for SEC_LINK_DUPLICATES means that the linker
235 should warn if there are any duplicate sections, although
236 it should still only link one copy. */
237 #define SEC_LINK_DUPLICATES_ONE_ONLY 0x80000
239 /* This value for SEC_LINK_DUPLICATES means that the linker
240 should warn if any duplicate sections are a different size. */
241 #define SEC_LINK_DUPLICATES_SAME_SIZE 0x100000
243 /* This value for SEC_LINK_DUPLICATES means that the linker
244 should warn if any duplicate sections contain different
245 contents. */
246 #define SEC_LINK_DUPLICATES_SAME_CONTENTS \
247 (SEC_LINK_DUPLICATES_ONE_ONLY | SEC_LINK_DUPLICATES_SAME_SIZE)
249 /* This section was created by the linker as part of dynamic
250 relocation or other arcane processing. It is skipped when
251 going through the first-pass output, trusting that someone
252 else up the line will take care of it later. */
253 #define SEC_LINKER_CREATED 0x200000
255 /* This section should not be subject to garbage collection. */
256 #define SEC_KEEP 0x400000
258 /* This section contains "short" data, and should be placed
259 "near" the GP. */
260 #define SEC_SMALL_DATA 0x800000
262 /* Attempt to merge identical entities in the section.
263 Entity size is given in the entsize field. */
264 #define SEC_MERGE 0x1000000
266 /* If given with SEC_MERGE, entities to merge are zero terminated
267 strings where entsize specifies character size instead of fixed
268 size entries. */
269 #define SEC_STRINGS 0x2000000
271 /* This section contains data about section groups. */
272 #define SEC_GROUP 0x4000000
274 /* The section is a COFF shared library section. This flag is
275 only for the linker. If this type of section appears in
276 the input file, the linker must copy it to the output file
277 without changing the vma or size. FIXME: Although this
278 was originally intended to be general, it really is COFF
279 specific (and the flag was renamed to indicate this). It
280 might be cleaner to have some more general mechanism to
281 allow the back end to control what the linker does with
282 sections. */
283 #define SEC_COFF_SHARED_LIBRARY 0x10000000
285 /* This section contains data which may be shared with other
286 executables or shared objects. This is for COFF only. */
287 #define SEC_COFF_SHARED 0x20000000
289 /* When a section with this flag is being linked, then if the size of
290 the input section is less than a page, it should not cross a page
291 boundary. If the size of the input section is one page or more,
292 it should be aligned on a page boundary. This is for TI
293 TMS320C54X only. */
294 #define SEC_TIC54X_BLOCK 0x40000000
296 /* Conditionally link this section; do not link if there are no
297 references found to any symbol in the section. This is for TI
298 TMS320C54X only. */
299 #define SEC_TIC54X_CLINK 0x80000000
301 /* End of section flags. */
303 /* Some internal packed boolean fields. */
305 /* See the vma field. */
306 unsigned int user_set_vma : 1;
308 /* A mark flag used by some of the linker backends. */
309 unsigned int linker_mark : 1;
311 /* Another mark flag used by some of the linker backends. Set for
312 output sections that have an input section. */
313 unsigned int linker_has_input : 1;
315 /* Mark flags used by some linker backends for garbage collection. */
316 unsigned int gc_mark : 1;
317 unsigned int gc_mark_from_eh : 1;
319 /* The following flags are used by the ELF linker. */
321 /* Mark sections which have been allocated to segments. */
322 unsigned int segment_mark : 1;
324 /* Type of sec_info information. */
325 unsigned int sec_info_type:3;
326 #define ELF_INFO_TYPE_NONE 0
327 #define ELF_INFO_TYPE_STABS 1
328 #define ELF_INFO_TYPE_MERGE 2
329 #define ELF_INFO_TYPE_EH_FRAME 3
330 #define ELF_INFO_TYPE_JUST_SYMS 4
332 /* Nonzero if this section uses RELA relocations, rather than REL. */
333 unsigned int use_rela_p:1;
335 /* Bits used by various backends. The generic code doesn't touch
336 these fields. */
338 /* Nonzero if this section has TLS related relocations. */
339 unsigned int has_tls_reloc:1;
341 /* Nonzero if this section has a gp reloc. */
342 unsigned int has_gp_reloc:1;
344 /* Nonzero if this section needs the relax finalize pass. */
345 unsigned int need_finalize_relax:1;
347 /* Whether relocations have been processed. */
348 unsigned int reloc_done : 1;
350 /* End of internal packed boolean fields. */
352 /* The virtual memory address of the section - where it will be
353 at run time. The symbols are relocated against this. The
354 user_set_vma flag is maintained by bfd; if it's not set, the
355 backend can assign addresses (for example, in @code{a.out}, where
356 the default address for @code{.data} is dependent on the specific
357 target and various flags). */
358 bfd_vma vma;
360 /* The load address of the section - where it would be in a
361 rom image; really only used for writing section header
362 information. */
363 bfd_vma lma;
365 /* The size of the section in octets, as it will be output.
366 Contains a value even if the section has no contents (e.g., the
367 size of @code{.bss}). */
368 bfd_size_type size;
370 /* For input sections, the original size on disk of the section, in
371 octets. This field is used by the linker relaxation code. It is
372 currently only set for sections where the linker relaxation scheme
373 doesn't cache altered section and reloc contents (stabs, eh_frame,
374 SEC_MERGE, some coff relaxing targets), and thus the original size
375 needs to be kept to read the section multiple times.
376 For output sections, rawsize holds the section size calculated on
377 a previous linker relaxation pass. */
378 bfd_size_type rawsize;
380 /* If this section is going to be output, then this value is the
381 offset in *bytes* into the output section of the first byte in the
382 input section (byte ==> smallest addressable unit on the
383 target). In most cases, if this was going to start at the
384 100th octet (8-bit quantity) in the output section, this value
385 would be 100. However, if the target byte size is 16 bits
386 (bfd_octets_per_byte is "2"), this value would be 50. */
387 bfd_vma output_offset;
389 /* The output section through which to map on output. */
390 struct bfd_section *output_section;
392 /* The alignment requirement of the section, as an exponent of 2 -
393 e.g., 3 aligns to 2^3 (or 8). */
394 unsigned int alignment_power;
396 /* If an input section, a pointer to a vector of relocation
397 records for the data in this section. */
398 struct reloc_cache_entry *relocation;
400 /* If an output section, a pointer to a vector of pointers to
401 relocation records for the data in this section. */
402 struct reloc_cache_entry **orelocation;
404 /* The number of relocation records in one of the above. */
405 unsigned reloc_count;
407 /* Information below is back end specific - and not always used
408 or updated. */
410 /* File position of section data. */
411 file_ptr filepos;
413 /* File position of relocation info. */
414 file_ptr rel_filepos;
416 /* File position of line data. */
417 file_ptr line_filepos;
419 /* Pointer to data for applications. */
420 void *userdata;
422 /* If the SEC_IN_MEMORY flag is set, this points to the actual
423 contents. */
424 unsigned char *contents;
426 /* Attached line number information. */
427 alent *lineno;
429 /* Number of line number records. */
430 unsigned int lineno_count;
432 /* Entity size for merging purposes. */
433 unsigned int entsize;
435 /* Points to the kept section if this section is a link-once section,
436 and is discarded. */
437 struct bfd_section *kept_section;
439 /* When a section is being output, this value changes as more
440 linenumbers are written out. */
441 file_ptr moving_line_filepos;
443 /* What the section number is in the target world. */
444 int target_index;
446 void *used_by_bfd;
448 /* If this is a constructor section then here is a list of the
449 relocations created to relocate items within it. */
450 struct relent_chain *constructor_chain;
452 /* The BFD which owns the section. */
453 bfd *owner;
455 /* A symbol which points at this section only. */
456 struct bfd_symbol *symbol;
457 struct bfd_symbol **symbol_ptr_ptr;
459 /* Early in the link process, map_head and map_tail are used to build
460 a list of input sections attached to an output section. Later,
461 output sections use these fields for a list of bfd_link_order
462 structs. */
463 union @{
464 struct bfd_link_order *link_order;
465 struct bfd_section *s;
466 @} map_head, map_tail;
467 @} asection;
469 /* These sections are global, and are managed by BFD. The application
470 and target back end are not permitted to change the values in
471 these sections. New code should use the section_ptr macros rather
472 than referring directly to the const sections. The const sections
473 may eventually vanish. */
474 #define BFD_ABS_SECTION_NAME "*ABS*"
475 #define BFD_UND_SECTION_NAME "*UND*"
476 #define BFD_COM_SECTION_NAME "*COM*"
477 #define BFD_IND_SECTION_NAME "*IND*"
479 /* The absolute section. */
480 extern asection bfd_abs_section;
481 #define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
482 #define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
483 /* Pointer to the undefined section. */
484 extern asection bfd_und_section;
485 #define bfd_und_section_ptr ((asection *) &bfd_und_section)
486 #define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
487 /* Pointer to the common section. */
488 extern asection bfd_com_section;
489 #define bfd_com_section_ptr ((asection *) &bfd_com_section)
490 /* Pointer to the indirect section. */
491 extern asection bfd_ind_section;
492 #define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
493 #define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
495 #define bfd_is_const_section(SEC) \
496 ( ((SEC) == bfd_abs_section_ptr) \
497 || ((SEC) == bfd_und_section_ptr) \
498 || ((SEC) == bfd_com_section_ptr) \
499 || ((SEC) == bfd_ind_section_ptr))
501 /* Macros to handle insertion and deletion of a bfd's sections. These
502 only handle the list pointers, ie. do not adjust section_count,
503 target_index etc. */
504 #define bfd_section_list_remove(ABFD, S) \
505 do \
506 @{ \
507 asection *_s = S; \
508 asection *_next = _s->next; \
509 asection *_prev = _s->prev; \
510 if (_prev) \
511 _prev->next = _next; \
512 else \
513 (ABFD)->sections = _next; \
514 if (_next) \
515 _next->prev = _prev; \
516 else \
517 (ABFD)->section_last = _prev; \
518 @} \
519 while (0)
520 #define bfd_section_list_append(ABFD, S) \
521 do \
522 @{ \
523 asection *_s = S; \
524 bfd *_abfd = ABFD; \
525 _s->next = NULL; \
526 if (_abfd->section_last) \
527 @{ \
528 _s->prev = _abfd->section_last; \
529 _abfd->section_last->next = _s; \
530 @} \
531 else \
532 @{ \
533 _s->prev = NULL; \
534 _abfd->sections = _s; \
535 @} \
536 _abfd->section_last = _s; \
537 @} \
538 while (0)
539 #define bfd_section_list_prepend(ABFD, S) \
540 do \
541 @{ \
542 asection *_s = S; \
543 bfd *_abfd = ABFD; \
544 _s->prev = NULL; \
545 if (_abfd->sections) \
546 @{ \
547 _s->next = _abfd->sections; \
548 _abfd->sections->prev = _s; \
549 @} \
550 else \
551 @{ \
552 _s->next = NULL; \
553 _abfd->section_last = _s; \
554 @} \
555 _abfd->sections = _s; \
556 @} \
557 while (0)
558 #define bfd_section_list_insert_after(ABFD, A, S) \
559 do \
560 @{ \
561 asection *_a = A; \
562 asection *_s = S; \
563 asection *_next = _a->next; \
564 _s->next = _next; \
565 _s->prev = _a; \
566 _a->next = _s; \
567 if (_next) \
568 _next->prev = _s; \
569 else \
570 (ABFD)->section_last = _s; \
571 @} \
572 while (0)
573 #define bfd_section_list_insert_before(ABFD, B, S) \
574 do \
575 @{ \
576 asection *_b = B; \
577 asection *_s = S; \
578 asection *_prev = _b->prev; \
579 _s->prev = _prev; \
580 _s->next = _b; \
581 _b->prev = _s; \
582 if (_prev) \
583 _prev->next = _s; \
584 else \
585 (ABFD)->sections = _s; \
586 @} \
587 while (0)
588 #define bfd_section_removed_from_list(ABFD, S) \
589 ((S)->next == NULL ? (ABFD)->section_last != (S) : (S)->next->prev != (S))
591 #define BFD_FAKE_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
592 /* name, id, index, next, prev, flags, user_set_vma, */ \
593 @{ NAME, IDX, 0, NULL, NULL, FLAGS, 0, \
594 \
595 /* linker_mark, linker_has_input, gc_mark, gc_mark_from_eh, */ \
596 0, 0, 1, 0, \
597 \
598 /* segment_mark, sec_info_type, use_rela_p, has_tls_reloc, */ \
599 0, 0, 0, 0, \
600 \
601 /* has_gp_reloc, need_finalize_relax, reloc_done, */ \
602 0, 0, 0, \
603 \
604 /* vma, lma, size, rawsize */ \
605 0, 0, 0, 0, \
606 \
607 /* output_offset, output_section, alignment_power, */ \
608 0, (struct bfd_section *) &SEC, 0, \
609 \
610 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
611 NULL, NULL, 0, 0, 0, \
612 \
613 /* line_filepos, userdata, contents, lineno, lineno_count, */ \
614 0, NULL, NULL, NULL, 0, \
615 \
616 /* entsize, kept_section, moving_line_filepos, */ \
617 0, NULL, 0, \
618 \
619 /* target_index, used_by_bfd, constructor_chain, owner, */ \
620 0, NULL, NULL, NULL, \
621 \
622 /* symbol, symbol_ptr_ptr, */ \
623 (struct bfd_symbol *) SYM, &SEC.symbol, \
624 \
625 /* map_head, map_tail */ \
626 @{ NULL @}, @{ NULL @} \
627 @}
629 @end example
631 @node section prototypes, , typedef asection, Sections
632 @subsection Section prototypes
633 These are the functions exported by the section handling part of BFD.
635 @findex bfd_section_list_clear
636 @subsubsection @code{bfd_section_list_clear}
637 @strong{Synopsis}
638 @example
639 void bfd_section_list_clear (bfd *);
640 @end example
641 @strong{Description}@*
642 Clears the section list, and also resets the section count and
643 hash table entries.
645 @findex bfd_get_section_by_name
646 @subsubsection @code{bfd_get_section_by_name}
647 @strong{Synopsis}
648 @example
649 asection *bfd_get_section_by_name (bfd *abfd, const char *name);
650 @end example
651 @strong{Description}@*
652 Run through @var{abfd} and return the one of the
653 @code{asection}s whose name matches @var{name}, otherwise @code{NULL}.
654 @xref{Sections}, for more information.
656 This should only be used in special cases; the normal way to process
657 all sections of a given name is to use @code{bfd_map_over_sections} and
658 @code{strcmp} on the name (or better yet, base it on the section flags
659 or something else) for each section.
661 @findex bfd_get_section_by_name_if
662 @subsubsection @code{bfd_get_section_by_name_if}
663 @strong{Synopsis}
664 @example
665 asection *bfd_get_section_by_name_if
666 (bfd *abfd,
667 const char *name,
668 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),
669 void *obj);
670 @end example
671 @strong{Description}@*
672 Call the provided function @var{func} for each section
673 attached to the BFD @var{abfd} whose name matches @var{name},
674 passing @var{obj} as an argument. The function will be called
675 as if by
677 @example
678 func (abfd, the_section, obj);
679 @end example
681 It returns the first section for which @var{func} returns true,
682 otherwise @code{NULL}.
684 @findex bfd_get_unique_section_name
685 @subsubsection @code{bfd_get_unique_section_name}
686 @strong{Synopsis}
687 @example
688 char *bfd_get_unique_section_name
689 (bfd *abfd, const char *templat, int *count);
690 @end example
691 @strong{Description}@*
692 Invent a section name that is unique in @var{abfd} by tacking
693 a dot and a digit suffix onto the original @var{templat}. If
694 @var{count} is non-NULL, then it specifies the first number
695 tried as a suffix to generate a unique name. The value
696 pointed to by @var{count} will be incremented in this case.
698 @findex bfd_make_section_old_way
699 @subsubsection @code{bfd_make_section_old_way}
700 @strong{Synopsis}
701 @example
702 asection *bfd_make_section_old_way (bfd *abfd, const char *name);
703 @end example
704 @strong{Description}@*
705 Create a new empty section called @var{name}
706 and attach it to the end of the chain of sections for the
707 BFD @var{abfd}. An attempt to create a section with a name which
708 is already in use returns its pointer without changing the
709 section chain.
711 It has the funny name since this is the way it used to be
712 before it was rewritten....
714 Possible errors are:
715 @itemize @bullet
717 @item
718 @code{bfd_error_invalid_operation} -
719 If output has already started for this BFD.
720 @item
721 @code{bfd_error_no_memory} -
722 If memory allocation fails.
723 @end itemize
725 @findex bfd_make_section_anyway_with_flags
726 @subsubsection @code{bfd_make_section_anyway_with_flags}
727 @strong{Synopsis}
728 @example
729 asection *bfd_make_section_anyway_with_flags
730 (bfd *abfd, const char *name, flagword flags);
731 @end example
732 @strong{Description}@*
733 Create a new empty section called @var{name} and attach it to the end of
734 the chain of sections for @var{abfd}. Create a new section even if there
735 is already a section with that name. Also set the attributes of the
736 new section to the value @var{flags}.
738 Return @code{NULL} and set @code{bfd_error} on error; possible errors are:
739 @itemize @bullet
741 @item
742 @code{bfd_error_invalid_operation} - If output has already started for @var{abfd}.
743 @item
744 @code{bfd_error_no_memory} - If memory allocation fails.
745 @end itemize
747 @findex bfd_make_section_anyway
748 @subsubsection @code{bfd_make_section_anyway}
749 @strong{Synopsis}
750 @example
751 asection *bfd_make_section_anyway (bfd *abfd, const char *name);
752 @end example
753 @strong{Description}@*
754 Create a new empty section called @var{name} and attach it to the end of
755 the chain of sections for @var{abfd}. Create a new section even if there
756 is already a section with that name.
758 Return @code{NULL} and set @code{bfd_error} on error; possible errors are:
759 @itemize @bullet
761 @item
762 @code{bfd_error_invalid_operation} - If output has already started for @var{abfd}.
763 @item
764 @code{bfd_error_no_memory} - If memory allocation fails.
765 @end itemize
767 @findex bfd_make_section_with_flags
768 @subsubsection @code{bfd_make_section_with_flags}
769 @strong{Synopsis}
770 @example
771 asection *bfd_make_section_with_flags
772 (bfd *, const char *name, flagword flags);
773 @end example
774 @strong{Description}@*
775 Like @code{bfd_make_section_anyway}, but return @code{NULL} (without calling
776 bfd_set_error ()) without changing the section chain if there is already a
777 section named @var{name}. Also set the attributes of the new section to
778 the value @var{flags}. If there is an error, return @code{NULL} and set
779 @code{bfd_error}.
781 @findex bfd_make_section
782 @subsubsection @code{bfd_make_section}
783 @strong{Synopsis}
784 @example
785 asection *bfd_make_section (bfd *, const char *name);
786 @end example
787 @strong{Description}@*
788 Like @code{bfd_make_section_anyway}, but return @code{NULL} (without calling
789 bfd_set_error ()) without changing the section chain if there is already a
790 section named @var{name}. If there is an error, return @code{NULL} and set
791 @code{bfd_error}.
793 @findex bfd_set_section_flags
794 @subsubsection @code{bfd_set_section_flags}
795 @strong{Synopsis}
796 @example
797 bfd_boolean bfd_set_section_flags
798 (bfd *abfd, asection *sec, flagword flags);
799 @end example
800 @strong{Description}@*
801 Set the attributes of the section @var{sec} in the BFD
802 @var{abfd} to the value @var{flags}. Return @code{TRUE} on success,
803 @code{FALSE} on error. Possible error returns are:
805 @itemize @bullet
807 @item
808 @code{bfd_error_invalid_operation} -
809 The section cannot have one or more of the attributes
810 requested. For example, a .bss section in @code{a.out} may not
811 have the @code{SEC_HAS_CONTENTS} field set.
812 @end itemize
814 @findex bfd_map_over_sections
815 @subsubsection @code{bfd_map_over_sections}
816 @strong{Synopsis}
817 @example
818 void bfd_map_over_sections
819 (bfd *abfd,
820 void (*func) (bfd *abfd, asection *sect, void *obj),
821 void *obj);
822 @end example
823 @strong{Description}@*
824 Call the provided function @var{func} for each section
825 attached to the BFD @var{abfd}, passing @var{obj} as an
826 argument. The function will be called as if by
828 @example
829 func (abfd, the_section, obj);
830 @end example
832 This is the preferred method for iterating over sections; an
833 alternative would be to use a loop:
835 @example
836 section *p;
837 for (p = abfd->sections; p != NULL; p = p->next)
838 func (abfd, p, ...)
839 @end example
841 @findex bfd_sections_find_if
842 @subsubsection @code{bfd_sections_find_if}
843 @strong{Synopsis}
844 @example
845 asection *bfd_sections_find_if
846 (bfd *abfd,
847 bfd_boolean (*operation) (bfd *abfd, asection *sect, void *obj),
848 void *obj);
849 @end example
850 @strong{Description}@*
851 Call the provided function @var{operation} for each section
852 attached to the BFD @var{abfd}, passing @var{obj} as an
853 argument. The function will be called as if by
855 @example
856 operation (abfd, the_section, obj);
857 @end example
859 It returns the first section for which @var{operation} returns true.
861 @findex bfd_set_section_size
862 @subsubsection @code{bfd_set_section_size}
863 @strong{Synopsis}
864 @example
865 bfd_boolean bfd_set_section_size
866 (bfd *abfd, asection *sec, bfd_size_type val);
867 @end example
868 @strong{Description}@*
869 Set @var{sec} to the size @var{val}. If the operation is
870 ok, then @code{TRUE} is returned, else @code{FALSE}.
872 Possible error returns:
873 @itemize @bullet
875 @item
876 @code{bfd_error_invalid_operation} -
877 Writing has started to the BFD, so setting the size is invalid.
878 @end itemize
880 @findex bfd_set_section_contents
881 @subsubsection @code{bfd_set_section_contents}
882 @strong{Synopsis}
883 @example
884 bfd_boolean bfd_set_section_contents
885 (bfd *abfd, asection *section, const void *data,
886 file_ptr offset, bfd_size_type count);
887 @end example
888 @strong{Description}@*
889 Sets the contents of the section @var{section} in BFD
890 @var{abfd} to the data starting in memory at @var{data}. The
891 data is written to the output section starting at offset
892 @var{offset} for @var{count} octets.
894 Normally @code{TRUE} is returned, else @code{FALSE}. Possible error
895 returns are:
896 @itemize @bullet
898 @item
899 @code{bfd_error_no_contents} -
900 The output section does not have the @code{SEC_HAS_CONTENTS}
901 attribute, so nothing can be written to it.
902 @item
903 and some more too
904 @end itemize
905 This routine is front end to the back end function
906 @code{_bfd_set_section_contents}.
908 @findex bfd_get_section_contents
909 @subsubsection @code{bfd_get_section_contents}
910 @strong{Synopsis}
911 @example
912 bfd_boolean bfd_get_section_contents
913 (bfd *abfd, asection *section, void *location, file_ptr offset,
914 bfd_size_type count);
915 @end example
916 @strong{Description}@*
917 Read data from @var{section} in BFD @var{abfd}
918 into memory starting at @var{location}. The data is read at an
919 offset of @var{offset} from the start of the input section,
920 and is read for @var{count} bytes.
922 If the contents of a constructor with the @code{SEC_CONSTRUCTOR}
923 flag set are requested or if the section does not have the
924 @code{SEC_HAS_CONTENTS} flag set, then the @var{location} is filled
925 with zeroes. If no errors occur, @code{TRUE} is returned, else
926 @code{FALSE}.
928 @findex bfd_malloc_and_get_section
929 @subsubsection @code{bfd_malloc_and_get_section}
930 @strong{Synopsis}
931 @example
932 bfd_boolean bfd_malloc_and_get_section
933 (bfd *abfd, asection *section, bfd_byte **buf);
934 @end example
935 @strong{Description}@*
936 Read all data from @var{section} in BFD @var{abfd}
937 into a buffer, *@var{buf}, malloc'd by this function.
939 @findex bfd_copy_private_section_data
940 @subsubsection @code{bfd_copy_private_section_data}
941 @strong{Synopsis}
942 @example
943 bfd_boolean bfd_copy_private_section_data
944 (bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
945 @end example
946 @strong{Description}@*
947 Copy private section information from @var{isec} in the BFD
948 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
949 Return @code{TRUE} on success, @code{FALSE} on error. Possible error
950 returns are:
952 @itemize @bullet
954 @item
955 @code{bfd_error_no_memory} -
956 Not enough memory exists to create private data for @var{osec}.
957 @end itemize
958 @example
959 #define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
960 BFD_SEND (obfd, _bfd_copy_private_section_data, \
961 (ibfd, isection, obfd, osection))
962 @end example
964 @findex bfd_generic_is_group_section
965 @subsubsection @code{bfd_generic_is_group_section}
966 @strong{Synopsis}
967 @example
968 bfd_boolean bfd_generic_is_group_section (bfd *, const asection *sec);
969 @end example
970 @strong{Description}@*
971 Returns TRUE if @var{sec} is a member of a group.
973 @findex bfd_generic_discard_group
974 @subsubsection @code{bfd_generic_discard_group}
975 @strong{Synopsis}
976 @example
977 bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group);
978 @end example
979 @strong{Description}@*
980 Remove all members of @var{group} from the output.