* config/tc-mn10200.c (md_parse_option <c, arg>): Add ATTRIBUTE_UNUSED.
[binutils.git] / bfd / section.c
blob35a0e5a6a05a31defb396d58ec2e35747515504f
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
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. */
24 SECTION
25 Sections
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>>.
34 @menu
35 @* Section Input::
36 @* Section Output::
37 @* typedef asection::
38 @* section prototypes::
39 @end menu
41 INODE
42 Section Input, Section Output, Sections, Sections
43 SUBSECTION
44 Section input
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
62 common storage.
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
72 relocations.
74 INODE
75 Section Output, typedef asection, Section Input, Sections
77 SUBSECTION
78 Section output
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:
105 | section name "A"
106 | output_offset 0x00
107 | size 0x20
108 | output_section -----------> section name "O"
109 | | vma 0x100
110 | section name "B" | size 0x123
111 | output_offset 0x20 |
112 | size 0x103 |
113 | output_section --------|
115 SUBSECTION
116 Link orders
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.
136 #include "bfd.h"
137 #include "sysdep.h"
138 #include "libbfd.h"
139 #include "bfdlink.h"
142 DOCDD
143 INODE
144 typedef asection, section prototypes, Section Output, Sections
145 SUBSECTION
146 typedef asection
148 Here is the section structure:
150 CODE_FRAGMENT
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. *}
160 . const char *name;
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. *}
166 . long symbol;
169 .typedef struct sec
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. *}
173 . const char *name;
175 . {* A unique sequence number. *}
176 . int id;
178 . {* Which section in the bfd; 0..n-1 as sections are created in a bfd. *}
179 . int index;
181 . {* The next section in the list belonging to the BFD, or NULL. *}
182 . struct sec *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. *}
187 . flagword flags;
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
230 . standard data. *}
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
250 . sections. *}
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
261 . static link. *}
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
274 . discarded. *}
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
318 . contents. *}
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
331 . "near" the GP. *}
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
354 . size entries. *}
355 .#define SEC_STRINGS 0x40000000
357 . {* This section contains data about section groups. *}
358 .#define SEC_GROUP 0x80000000
360 . {* End of section flags. *}
362 . {* Some internal packed boolean fields. *}
364 . {* See the vma field. *}
365 . unsigned int user_set_vma : 1;
367 . {* Whether relocations have been processed. *}
368 . unsigned int reloc_done : 1;
370 . {* A mark flag used by some of the linker backends. *}
371 . unsigned int linker_mark : 1;
373 . {* Another mark flag used by some of the linker backends. Set for
374 . output sections that have an input section. *}
375 . unsigned int linker_has_input : 1;
377 . {* A mark flag used by some linker backends for garbage collection. *}
378 . unsigned int gc_mark : 1;
380 . {* Used by the ELF code to mark sections which have been allocated
381 . to segments. *}
382 . unsigned int segment_mark : 1;
384 . {* End of internal packed boolean fields. *}
386 . {* The virtual memory address of the section - where it will be
387 . at run time. The symbols are relocated against this. The
388 . user_set_vma flag is maintained by bfd; if it's not set, the
389 . backend can assign addresses (for example, in <<a.out>>, where
390 . the default address for <<.data>> is dependent on the specific
391 . target and various flags). *}
392 . bfd_vma vma;
394 . {* The load address of the section - where it would be in a
395 . rom image; really only used for writing section header
396 . information. *}
397 . bfd_vma lma;
399 . {* The size of the section in octets, as it will be output.
400 . Contains a value even if the section has no contents (e.g., the
401 . size of <<.bss>>). This will be filled in after relocation. *}
402 . bfd_size_type _cooked_size;
404 . {* The original size on disk of the section, in octets. Normally this
405 . value is the same as the size, but if some relaxing has
406 . been done, then this value will be bigger. *}
407 . bfd_size_type _raw_size;
409 . {* If this section is going to be output, then this value is the
410 . offset in *bytes* into the output section of the first byte in the
411 . input section (byte ==> smallest addressable unit on the
412 . target). In most cases, if this was going to start at the
413 . 100th octet (8-bit quantity) in the output section, this value
414 . would be 100. However, if the target byte size is 16 bits
415 . (bfd_octets_per_byte is "2"), this value would be 50. *}
416 . bfd_vma output_offset;
418 . {* The output section through which to map on output. *}
419 . struct sec *output_section;
421 . {* The alignment requirement of the section, as an exponent of 2 -
422 . e.g., 3 aligns to 2^3 (or 8). *}
423 . unsigned int alignment_power;
425 . {* If an input section, a pointer to a vector of relocation
426 . records for the data in this section. *}
427 . struct reloc_cache_entry *relocation;
429 . {* If an output section, a pointer to a vector of pointers to
430 . relocation records for the data in this section. *}
431 . struct reloc_cache_entry **orelocation;
433 . {* The number of relocation records in one of the above. *}
434 . unsigned reloc_count;
436 . {* Information below is back end specific - and not always used
437 . or updated. *}
439 . {* File position of section data. *}
440 . file_ptr filepos;
442 . {* File position of relocation info. *}
443 . file_ptr rel_filepos;
445 . {* File position of line data. *}
446 . file_ptr line_filepos;
448 . {* Pointer to data for applications. *}
449 . PTR userdata;
451 . {* If the SEC_IN_MEMORY flag is set, this points to the actual
452 . contents. *}
453 . unsigned char *contents;
455 . {* Attached line number information. *}
456 . alent *lineno;
458 . {* Number of line number records. *}
459 . unsigned int lineno_count;
461 . {* Entity size for merging purposes. *}
462 . unsigned int entsize;
464 . {* Optional information about a COMDAT entry; NULL if not COMDAT. *}
465 . struct bfd_comdat_info *comdat;
467 . {* When a section is being output, this value changes as more
468 . linenumbers are written out. *}
469 . file_ptr moving_line_filepos;
471 . {* What the section number is in the target world. *}
472 . int target_index;
474 . PTR used_by_bfd;
476 . {* If this is a constructor section then here is a list of the
477 . relocations created to relocate items within it. *}
478 . struct relent_chain *constructor_chain;
480 . {* The BFD which owns the section. *}
481 . bfd *owner;
483 . {* A symbol which points at this section only. *}
484 . struct symbol_cache_entry *symbol;
485 . struct symbol_cache_entry **symbol_ptr_ptr;
487 . struct bfd_link_order *link_order_head;
488 . struct bfd_link_order *link_order_tail;
489 .} asection;
491 .{* These sections are global, and are managed by BFD. The application
492 . and target back end are not permitted to change the values in
493 . these sections. New code should use the section_ptr macros rather
494 . than referring directly to the const sections. The const sections
495 . may eventually vanish. *}
496 .#define BFD_ABS_SECTION_NAME "*ABS*"
497 .#define BFD_UND_SECTION_NAME "*UND*"
498 .#define BFD_COM_SECTION_NAME "*COM*"
499 .#define BFD_IND_SECTION_NAME "*IND*"
501 .{* The absolute section. *}
502 .extern const asection bfd_abs_section;
503 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
504 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
505 .{* Pointer to the undefined section. *}
506 .extern const asection bfd_und_section;
507 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
508 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
509 .{* Pointer to the common section. *}
510 .extern const asection bfd_com_section;
511 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
512 .{* Pointer to the indirect section. *}
513 .extern const asection bfd_ind_section;
514 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
515 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
517 .#define bfd_is_const_section(SEC) \
518 . ( ((SEC) == bfd_abs_section_ptr) \
519 . || ((SEC) == bfd_und_section_ptr) \
520 . || ((SEC) == bfd_com_section_ptr) \
521 . || ((SEC) == bfd_ind_section_ptr))
523 .extern const struct symbol_cache_entry * const bfd_abs_symbol;
524 .extern const struct symbol_cache_entry * const bfd_com_symbol;
525 .extern const struct symbol_cache_entry * const bfd_und_symbol;
526 .extern const struct symbol_cache_entry * const bfd_ind_symbol;
527 .#define bfd_get_section_size_before_reloc(section) \
528 . ((section)->reloc_done ? (abort (), (bfd_size_type) 1) \
529 . : (section)->_raw_size)
530 .#define bfd_get_section_size_after_reloc(section) \
531 . ((section)->reloc_done ? (section)->_cooked_size \
532 . : (abort (), (bfd_size_type) 1))
534 .{* Macros to handle insertion and deletion of a bfd's sections. These
535 . only handle the list pointers, ie. do not adjust section_count,
536 . target_index etc. *}
537 .#define bfd_section_list_remove(ABFD, PS) \
538 . do \
539 . { \
540 . asection **_ps = PS; \
541 . asection *_s = *_ps; \
542 . *_ps = _s->next; \
543 . if (_s->next == NULL) \
544 . (ABFD)->section_tail = _ps; \
545 . } \
546 . while (0)
547 .#define bfd_section_list_insert(ABFD, PS, S) \
548 . do \
549 . { \
550 . asection **_ps = PS; \
551 . asection *_s = S; \
552 . _s->next = *_ps; \
553 . *_ps = _s; \
554 . if (_s->next == NULL) \
555 . (ABFD)->section_tail = &_s->next; \
556 . } \
557 . while (0)
561 /* We use a macro to initialize the static asymbol structures because
562 traditional C does not permit us to initialize a union member while
563 gcc warns if we don't initialize it. */
564 /* the_bfd, name, value, attr, section [, udata] */
565 #ifdef __STDC__
566 #define GLOBAL_SYM_INIT(NAME, SECTION) \
567 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION, { 0 }}
568 #else
569 #define GLOBAL_SYM_INIT(NAME, SECTION) \
570 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION }
571 #endif
573 /* These symbols are global, not specific to any BFD. Therefore, anything
574 that tries to change them is broken, and should be repaired. */
576 static const asymbol global_syms[] =
578 GLOBAL_SYM_INIT (BFD_COM_SECTION_NAME, &bfd_com_section),
579 GLOBAL_SYM_INIT (BFD_UND_SECTION_NAME, &bfd_und_section),
580 GLOBAL_SYM_INIT (BFD_ABS_SECTION_NAME, &bfd_abs_section),
581 GLOBAL_SYM_INIT (BFD_IND_SECTION_NAME, &bfd_ind_section)
584 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
585 const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
586 const asection SEC = \
587 /* name, id, index, next, flags, user_set_vma, reloc_done, */ \
588 { NAME, IDX, 0, NULL, FLAGS, 0, 0, \
590 /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \
591 0, 0, 1, 0, \
593 /* vma, lma, _cooked_size, _raw_size, */ \
594 0, 0, 0, 0, \
596 /* output_offset, output_section, alignment_power, */ \
597 0, (struct sec *) &SEC, 0, \
599 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
600 NULL, NULL, 0, 0, 0, \
602 /* line_filepos, userdata, contents, lineno, lineno_count, */ \
603 0, NULL, NULL, NULL, 0, \
605 /* entsize, comdat, moving_line_filepos, */ \
606 0, NULL, 0, \
608 /* target_index, used_by_bfd, constructor_chain, owner, */ \
609 0, NULL, NULL, NULL, \
611 /* symbol, */ \
612 (struct symbol_cache_entry *) &global_syms[IDX], \
614 /* symbol_ptr_ptr, */ \
615 (struct symbol_cache_entry **) &SYM, \
617 /* link_order_head, link_order_tail */ \
618 NULL, NULL \
621 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
622 BFD_COM_SECTION_NAME, 0);
623 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
624 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
625 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
626 #undef STD_SECTION
628 struct section_hash_entry
630 struct bfd_hash_entry root;
631 asection section;
634 /* Initialize an entry in the section hash table. */
636 struct bfd_hash_entry *
637 bfd_section_hash_newfunc (entry, table, string)
638 struct bfd_hash_entry *entry;
639 struct bfd_hash_table *table;
640 const char *string;
642 /* Allocate the structure if it has not already been allocated by a
643 subclass. */
644 if (entry == NULL)
646 entry = (struct bfd_hash_entry *)
647 bfd_hash_allocate (table, sizeof (struct section_hash_entry));
648 if (entry == NULL)
649 return entry;
652 /* Call the allocation method of the superclass. */
653 entry = bfd_hash_newfunc (entry, table, string);
654 if (entry != NULL)
656 memset ((PTR) &((struct section_hash_entry *) entry)->section,
657 0, sizeof (asection));
660 return entry;
663 #define section_hash_lookup(table, string, create, copy) \
664 ((struct section_hash_entry *) \
665 bfd_hash_lookup ((table), (string), (create), (copy)))
667 /* Initializes a new section. NEWSECT->NAME is already set. */
669 static asection *bfd_section_init PARAMS ((bfd *, asection *));
671 static asection *
672 bfd_section_init (abfd, newsect)
673 bfd *abfd;
674 asection *newsect;
676 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */
678 newsect->id = section_id;
679 newsect->index = abfd->section_count;
680 newsect->owner = abfd;
682 /* Create a symbol whose only job is to point to this section. This
683 is useful for things like relocs which are relative to the base
684 of a section. */
685 newsect->symbol = bfd_make_empty_symbol (abfd);
686 if (newsect->symbol == NULL)
687 return NULL;
689 newsect->symbol->name = newsect->name;
690 newsect->symbol->value = 0;
691 newsect->symbol->section = newsect;
692 newsect->symbol->flags = BSF_SECTION_SYM;
694 newsect->symbol_ptr_ptr = &newsect->symbol;
696 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect)))
697 return NULL;
699 section_id++;
700 abfd->section_count++;
701 *abfd->section_tail = newsect;
702 abfd->section_tail = &newsect->next;
703 return newsect;
707 DOCDD
708 INODE
709 section prototypes, , typedef asection, Sections
710 SUBSECTION
711 Section prototypes
713 These are the functions exported by the section handling part of BFD.
717 FUNCTION
718 bfd_section_list_clear
720 SYNOPSIS
721 void bfd_section_list_clear (bfd *);
723 DESCRIPTION
724 Clears the section list, and also resets the section count and
725 hash table entries.
728 void
729 bfd_section_list_clear (abfd)
730 bfd *abfd;
732 abfd->sections = NULL;
733 abfd->section_tail = &abfd->sections;
734 abfd->section_count = 0;
735 memset ((PTR) abfd->section_htab.table, 0,
736 abfd->section_htab.size * sizeof (struct bfd_hash_entry *));
740 FUNCTION
741 bfd_get_section_by_name
743 SYNOPSIS
744 asection *bfd_get_section_by_name(bfd *abfd, const char *name);
746 DESCRIPTION
747 Run through @var{abfd} and return the one of the
748 <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
749 @xref{Sections}, for more information.
751 This should only be used in special cases; the normal way to process
752 all sections of a given name is to use <<bfd_map_over_sections>> and
753 <<strcmp>> on the name (or better yet, base it on the section flags
754 or something else) for each section.
757 asection *
758 bfd_get_section_by_name (abfd, name)
759 bfd *abfd;
760 const char *name;
762 struct section_hash_entry *sh;
764 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
765 if (sh != NULL)
766 return &sh->section;
768 return NULL;
772 FUNCTION
773 bfd_get_unique_section_name
775 SYNOPSIS
776 char *bfd_get_unique_section_name(bfd *abfd,
777 const char *templat,
778 int *count);
780 DESCRIPTION
781 Invent a section name that is unique in @var{abfd} by tacking
782 a dot and a digit suffix onto the original @var{templat}. If
783 @var{count} is non-NULL, then it specifies the first number
784 tried as a suffix to generate a unique name. The value
785 pointed to by @var{count} will be incremented in this case.
788 char *
789 bfd_get_unique_section_name (abfd, templat, count)
790 bfd *abfd;
791 const char *templat;
792 int *count;
794 int num;
795 unsigned int len;
796 char *sname;
798 len = strlen (templat);
799 sname = bfd_malloc ((bfd_size_type) len + 8);
800 if (sname == NULL)
801 return NULL;
802 memcpy (sname, templat, len);
803 num = 1;
804 if (count != NULL)
805 num = *count;
809 /* If we have a million sections, something is badly wrong. */
810 if (num > 999999)
811 abort ();
812 sprintf (sname + len, ".%d", num++);
814 while (section_hash_lookup (&abfd->section_htab, sname, FALSE, FALSE));
816 if (count != NULL)
817 *count = num;
818 return sname;
822 FUNCTION
823 bfd_make_section_old_way
825 SYNOPSIS
826 asection *bfd_make_section_old_way(bfd *abfd, const char *name);
828 DESCRIPTION
829 Create a new empty section called @var{name}
830 and attach it to the end of the chain of sections for the
831 BFD @var{abfd}. An attempt to create a section with a name which
832 is already in use returns its pointer without changing the
833 section chain.
835 It has the funny name since this is the way it used to be
836 before it was rewritten....
838 Possible errors are:
839 o <<bfd_error_invalid_operation>> -
840 If output has already started for this BFD.
841 o <<bfd_error_no_memory>> -
842 If memory allocation fails.
846 asection *
847 bfd_make_section_old_way (abfd, name)
848 bfd *abfd;
849 const char *name;
851 struct section_hash_entry *sh;
852 asection *newsect;
854 if (abfd->output_has_begun)
856 bfd_set_error (bfd_error_invalid_operation);
857 return NULL;
860 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
861 return bfd_abs_section_ptr;
863 if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
864 return bfd_com_section_ptr;
866 if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
867 return bfd_und_section_ptr;
869 if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
870 return bfd_ind_section_ptr;
872 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
873 if (sh == NULL)
874 return NULL;
876 newsect = &sh->section;
877 if (newsect->name != NULL)
879 /* Section already exists. */
880 return newsect;
883 newsect->name = name;
884 return bfd_section_init (abfd, newsect);
888 FUNCTION
889 bfd_make_section_anyway
891 SYNOPSIS
892 asection *bfd_make_section_anyway(bfd *abfd, const char *name);
894 DESCRIPTION
895 Create a new empty section called @var{name} and attach it to the end of
896 the chain of sections for @var{abfd}. Create a new section even if there
897 is already a section with that name.
899 Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
900 o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
901 o <<bfd_error_no_memory>> - If memory allocation fails.
904 sec_ptr
905 bfd_make_section_anyway (abfd, name)
906 bfd *abfd;
907 const char *name;
909 struct section_hash_entry *sh;
910 asection *newsect;
912 if (abfd->output_has_begun)
914 bfd_set_error (bfd_error_invalid_operation);
915 return NULL;
918 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
919 if (sh == NULL)
920 return NULL;
922 newsect = &sh->section;
923 if (newsect->name != NULL)
925 /* We are making a section of the same name. It can't go in
926 section_htab without generating a unique section name and
927 that would be pointless; We don't need to traverse the
928 hash table. */
929 newsect = (asection *) bfd_zalloc (abfd, sizeof (asection));
930 if (newsect == NULL)
931 return NULL;
934 newsect->name = name;
935 return bfd_section_init (abfd, newsect);
939 FUNCTION
940 bfd_make_section
942 SYNOPSIS
943 asection *bfd_make_section(bfd *, const char *name);
945 DESCRIPTION
946 Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
947 bfd_set_error ()) without changing the section chain if there is already a
948 section named @var{name}. If there is an error, return <<NULL>> and set
949 <<bfd_error>>.
952 asection *
953 bfd_make_section (abfd, name)
954 bfd *abfd;
955 const char *name;
957 struct section_hash_entry *sh;
958 asection *newsect;
960 if (abfd->output_has_begun)
962 bfd_set_error (bfd_error_invalid_operation);
963 return NULL;
966 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0
967 || strcmp (name, BFD_COM_SECTION_NAME) == 0
968 || strcmp (name, BFD_UND_SECTION_NAME) == 0
969 || strcmp (name, BFD_IND_SECTION_NAME) == 0)
970 return NULL;
972 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
973 if (sh == NULL)
974 return NULL;
976 newsect = &sh->section;
977 if (newsect->name != NULL)
979 /* Section already exists. */
980 return newsect;
983 newsect->name = name;
984 return bfd_section_init (abfd, newsect);
988 FUNCTION
989 bfd_set_section_flags
991 SYNOPSIS
992 bfd_boolean bfd_set_section_flags (bfd *abfd, asection *sec, flagword flags);
994 DESCRIPTION
995 Set the attributes of the section @var{sec} in the BFD
996 @var{abfd} to the value @var{flags}. Return <<TRUE>> on success,
997 <<FALSE>> on error. Possible error returns are:
999 o <<bfd_error_invalid_operation>> -
1000 The section cannot have one or more of the attributes
1001 requested. For example, a .bss section in <<a.out>> may not
1002 have the <<SEC_HAS_CONTENTS>> field set.
1006 /*ARGSUSED*/
1007 bfd_boolean
1008 bfd_set_section_flags (abfd, section, flags)
1009 bfd *abfd ATTRIBUTE_UNUSED;
1010 sec_ptr section;
1011 flagword flags;
1013 #if 0
1014 /* If you try to copy a text section from an input file (where it
1015 has the SEC_CODE flag set) to an output file, this loses big if
1016 the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
1017 set - which it doesn't, at least not for a.out. FIXME */
1019 if ((flags & bfd_applicable_section_flags (abfd)) != flags)
1021 bfd_set_error (bfd_error_invalid_operation);
1022 return FALSE;
1024 #endif
1026 section->flags = flags;
1027 return TRUE;
1031 FUNCTION
1032 bfd_map_over_sections
1034 SYNOPSIS
1035 void bfd_map_over_sections(bfd *abfd,
1036 void (*func) (bfd *abfd,
1037 asection *sect,
1038 PTR obj),
1039 PTR obj);
1041 DESCRIPTION
1042 Call the provided function @var{func} for each section
1043 attached to the BFD @var{abfd}, passing @var{obj} as an
1044 argument. The function will be called as if by
1046 | func(abfd, the_section, obj);
1048 This is the prefered method for iterating over sections; an
1049 alternative would be to use a loop:
1051 | section *p;
1052 | for (p = abfd->sections; p != NULL; p = p->next)
1053 | func(abfd, p, ...)
1057 /*VARARGS2*/
1058 void
1059 bfd_map_over_sections (abfd, operation, user_storage)
1060 bfd *abfd;
1061 void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj));
1062 PTR user_storage;
1064 asection *sect;
1065 unsigned int i = 0;
1067 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
1068 (*operation) (abfd, sect, user_storage);
1070 if (i != abfd->section_count) /* Debugging */
1071 abort ();
1075 FUNCTION
1076 bfd_set_section_size
1078 SYNOPSIS
1079 bfd_boolean bfd_set_section_size (bfd *abfd, asection *sec, bfd_size_type val);
1081 DESCRIPTION
1082 Set @var{sec} to the size @var{val}. If the operation is
1083 ok, then <<TRUE>> is returned, else <<FALSE>>.
1085 Possible error returns:
1086 o <<bfd_error_invalid_operation>> -
1087 Writing has started to the BFD, so setting the size is invalid.
1091 bfd_boolean
1092 bfd_set_section_size (abfd, ptr, val)
1093 bfd *abfd;
1094 sec_ptr ptr;
1095 bfd_size_type val;
1097 /* Once you've started writing to any section you cannot create or change
1098 the size of any others. */
1100 if (abfd->output_has_begun)
1102 bfd_set_error (bfd_error_invalid_operation);
1103 return FALSE;
1106 ptr->_cooked_size = val;
1107 ptr->_raw_size = val;
1109 return TRUE;
1113 FUNCTION
1114 bfd_set_section_contents
1116 SYNOPSIS
1117 bfd_boolean bfd_set_section_contents (bfd *abfd, asection *section,
1118 PTR data, file_ptr offset,
1119 bfd_size_type count);
1121 DESCRIPTION
1122 Sets the contents of the section @var{section} in BFD
1123 @var{abfd} to the data starting in memory at @var{data}. The
1124 data is written to the output section starting at offset
1125 @var{offset} for @var{count} octets.
1127 Normally <<TRUE>> is returned, else <<FALSE>>. Possible error
1128 returns are:
1129 o <<bfd_error_no_contents>> -
1130 The output section does not have the <<SEC_HAS_CONTENTS>>
1131 attribute, so nothing can be written to it.
1132 o and some more too
1134 This routine is front end to the back end function
1135 <<_bfd_set_section_contents>>.
1139 #define bfd_get_section_size_now(abfd,sec) \
1140 (sec->reloc_done \
1141 ? bfd_get_section_size_after_reloc (sec) \
1142 : bfd_get_section_size_before_reloc (sec))
1144 bfd_boolean
1145 bfd_set_section_contents (abfd, section, location, offset, count)
1146 bfd *abfd;
1147 sec_ptr section;
1148 PTR location;
1149 file_ptr offset;
1150 bfd_size_type count;
1152 bfd_size_type sz;
1154 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
1156 bfd_set_error (bfd_error_no_contents);
1157 return FALSE;
1160 sz = bfd_get_section_size_now (abfd, section);
1161 if ((bfd_size_type) offset > sz
1162 || count > sz
1163 || offset + count > sz
1164 || count != (size_t) count)
1166 bfd_set_error (bfd_error_bad_value);
1167 return FALSE;
1170 switch (abfd->direction)
1172 case read_direction:
1173 case no_direction:
1174 bfd_set_error (bfd_error_invalid_operation);
1175 return FALSE;
1177 case write_direction:
1178 break;
1180 case both_direction:
1181 /* File is opened for update. `output_has_begun' some time ago when
1182 the file was created. Do not recompute sections sizes or alignments
1183 in _bfd_set_section_content. */
1184 abfd->output_has_begun = TRUE;
1185 break;
1188 /* Record a copy of the data in memory if desired. */
1189 if (section->contents
1190 && location != (PTR) (section->contents + offset))
1191 memcpy (section->contents + offset, location, (size_t) count);
1193 if (BFD_SEND (abfd, _bfd_set_section_contents,
1194 (abfd, section, location, offset, count)))
1196 abfd->output_has_begun = TRUE;
1197 return TRUE;
1200 return FALSE;
1204 FUNCTION
1205 bfd_get_section_contents
1207 SYNOPSIS
1208 bfd_boolean bfd_get_section_contents (bfd *abfd, asection *section,
1209 PTR location, file_ptr offset,
1210 bfd_size_type count);
1212 DESCRIPTION
1213 Read data from @var{section} in BFD @var{abfd}
1214 into memory starting at @var{location}. The data is read at an
1215 offset of @var{offset} from the start of the input section,
1216 and is read for @var{count} bytes.
1218 If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
1219 flag set are requested or if the section does not have the
1220 <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
1221 with zeroes. If no errors occur, <<TRUE>> is returned, else
1222 <<FALSE>>.
1225 bfd_boolean
1226 bfd_get_section_contents (abfd, section, location, offset, count)
1227 bfd *abfd;
1228 sec_ptr section;
1229 PTR location;
1230 file_ptr offset;
1231 bfd_size_type count;
1233 bfd_size_type sz;
1235 if (section->flags & SEC_CONSTRUCTOR)
1237 memset (location, 0, (size_t) count);
1238 return TRUE;
1241 /* Even if reloc_done is TRUE, this function reads unrelocated
1242 contents, so we want the raw size. */
1243 sz = section->_raw_size;
1244 if ((bfd_size_type) offset > sz
1245 || count > sz
1246 || offset + count > sz
1247 || count != (size_t) count)
1249 bfd_set_error (bfd_error_bad_value);
1250 return FALSE;
1253 if (count == 0)
1254 /* Don't bother. */
1255 return TRUE;
1257 if ((section->flags & SEC_HAS_CONTENTS) == 0)
1259 memset (location, 0, (size_t) count);
1260 return TRUE;
1263 if ((section->flags & SEC_IN_MEMORY) != 0)
1265 memcpy (location, section->contents + offset, (size_t) count);
1266 return TRUE;
1269 return BFD_SEND (abfd, _bfd_get_section_contents,
1270 (abfd, section, location, offset, count));
1274 FUNCTION
1275 bfd_copy_private_section_data
1277 SYNOPSIS
1278 bfd_boolean bfd_copy_private_section_data (bfd *ibfd, asection *isec,
1279 bfd *obfd, asection *osec);
1281 DESCRIPTION
1282 Copy private section information from @var{isec} in the BFD
1283 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1284 Return <<TRUE>> on success, <<FALSE>> on error. Possible error
1285 returns are:
1287 o <<bfd_error_no_memory>> -
1288 Not enough memory exists to create private data for @var{osec}.
1290 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1291 . BFD_SEND (obfd, _bfd_copy_private_section_data, \
1292 . (ibfd, isection, obfd, osection))
1296 FUNCTION
1297 _bfd_strip_section_from_output
1299 SYNOPSIS
1300 void _bfd_strip_section_from_output
1301 (struct bfd_link_info *info, asection *section);
1303 DESCRIPTION
1304 Remove @var{section} from the output. If the output section
1305 becomes empty, remove it from the output bfd.
1307 This function won't actually do anything except twiddle flags
1308 if called too late in the linking process, when it's not safe
1309 to remove sections.
1311 void
1312 _bfd_strip_section_from_output (info, s)
1313 struct bfd_link_info *info;
1314 asection *s;
1316 asection *os;
1317 asection *is;
1318 bfd *abfd;
1320 s->flags |= SEC_EXCLUDE;
1322 /* If the section wasn't assigned to an output section, or the
1323 section has been discarded by the linker script, there's nothing
1324 more to do. */
1325 os = s->output_section;
1326 if (os == NULL || os->owner == NULL)
1327 return;
1329 /* If the output section has other (non-excluded) input sections, we
1330 can't remove it. */
1331 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
1332 for (is = abfd->sections; is != NULL; is = is->next)
1333 if (is->output_section == os && (is->flags & SEC_EXCLUDE) == 0)
1334 return;
1336 /* If the output section is empty, flag it for removal too.
1337 See ldlang.c:strip_excluded_output_sections for the action. */
1338 os->flags |= SEC_EXCLUDE;
1342 FUNCTION
1343 bfd_generic_discard_group
1345 SYNOPSIS
1346 bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group);
1348 DESCRIPTION
1349 Remove all members of @var{group} from the output.
1352 bfd_boolean
1353 bfd_generic_discard_group (abfd, group)
1354 bfd *abfd ATTRIBUTE_UNUSED;
1355 asection *group ATTRIBUTE_UNUSED;
1357 return TRUE;