bfd/
[binutils.git] / bfd / section.c
blobb9272dbba7c453ab118a284578e99bdbf9d69fbd
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. */
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 .typedef struct bfd_section
154 . {* The name of the section; the name isn't a copy, the pointer is
155 . the same as that passed to bfd_make_section. *}
156 . const char *name;
158 . {* A unique sequence number. *}
159 . int id;
161 . {* Which section in the bfd; 0..n-1 as sections are created in a bfd. *}
162 . int index;
164 . {* The next section in the list belonging to the BFD, or NULL. *}
165 . struct bfd_section *next;
167 . {* The field flags contains attributes of the section. Some
168 . flags are read in from the object file, and some are
169 . synthesized from other information. *}
170 . flagword flags;
172 .#define SEC_NO_FLAGS 0x000
174 . {* Tells the OS to allocate space for this section when loading.
175 . This is clear for a section containing debug information only. *}
176 .#define SEC_ALLOC 0x001
178 . {* Tells the OS to load the section from the file when loading.
179 . This is clear for a .bss section. *}
180 .#define SEC_LOAD 0x002
182 . {* The section contains data still to be relocated, so there is
183 . some relocation information too. *}
184 .#define SEC_RELOC 0x004
186 . {* ELF reserves 4 processor specific bits and 8 operating system
187 . specific bits in sh_flags; at present we can get away with just
188 . one in communicating between the assembler and BFD, but this
189 . isn't a good long-term solution. *}
190 .#define SEC_ARCH_BIT_0 0x008
192 . {* A signal to the OS that the section contains read only data. *}
193 .#define SEC_READONLY 0x010
195 . {* The section contains code only. *}
196 .#define SEC_CODE 0x020
198 . {* The section contains data only. *}
199 .#define SEC_DATA 0x040
201 . {* The section will reside in ROM. *}
202 .#define SEC_ROM 0x080
204 . {* The section contains constructor information. This section
205 . type is used by the linker to create lists of constructors and
206 . destructors used by <<g++>>. When a back end sees a symbol
207 . which should be used in a constructor list, it creates a new
208 . section for the type of name (e.g., <<__CTOR_LIST__>>), attaches
209 . the symbol to it, and builds a relocation. To build the lists
210 . of constructors, all the linker has to do is catenate all the
211 . sections called <<__CTOR_LIST__>> and relocate the data
212 . contained within - exactly the operations it would peform on
213 . standard data. *}
214 .#define SEC_CONSTRUCTOR 0x100
216 . {* The section has contents - a data section could be
217 . <<SEC_ALLOC>> | <<SEC_HAS_CONTENTS>>; a debug section could be
218 . <<SEC_HAS_CONTENTS>> *}
219 .#define SEC_HAS_CONTENTS 0x200
221 . {* An instruction to the linker to not output the section
222 . even if it has information which would normally be written. *}
223 .#define SEC_NEVER_LOAD 0x400
225 . {* The section is a COFF shared library section. This flag is
226 . only for the linker. If this type of section appears in
227 . the input file, the linker must copy it to the output file
228 . without changing the vma or size. FIXME: Although this
229 . was originally intended to be general, it really is COFF
230 . specific (and the flag was renamed to indicate this). It
231 . might be cleaner to have some more general mechanism to
232 . allow the back end to control what the linker does with
233 . sections. *}
234 .#define SEC_COFF_SHARED_LIBRARY 0x800
236 . {* The section contains thread local data. *}
237 .#define SEC_THREAD_LOCAL 0x1000
239 . {* The section has GOT references. This flag is only for the
240 . linker, and is currently only used by the elf32-hppa back end.
241 . It will be set if global offset table references were detected
242 . in this section, which indicate to the linker that the section
243 . contains PIC code, and must be handled specially when doing a
244 . static link. *}
245 .#define SEC_HAS_GOT_REF 0x4000
247 . {* The section contains common symbols (symbols may be defined
248 . multiple times, the value of a symbol is the amount of
249 . space it requires, and the largest symbol value is the one
250 . used). Most targets have exactly one of these (which we
251 . translate to bfd_com_section_ptr), but ECOFF has two. *}
252 .#define SEC_IS_COMMON 0x8000
254 . {* The section contains only debugging information. For
255 . example, this is set for ELF .debug and .stab sections.
256 . strip tests this flag to see if a section can be
257 . discarded. *}
258 .#define SEC_DEBUGGING 0x10000
260 . {* The contents of this section are held in memory pointed to
261 . by the contents field. This is checked by bfd_get_section_contents,
262 . and the data is retrieved from memory if appropriate. *}
263 .#define SEC_IN_MEMORY 0x20000
265 . {* The contents of this section are to be excluded by the
266 . linker for executable and shared objects unless those
267 . objects are to be further relocated. *}
268 .#define SEC_EXCLUDE 0x40000
270 . {* The contents of this section are to be sorted based on the sum of
271 . the symbol and addend values specified by the associated relocation
272 . entries. Entries without associated relocation entries will be
273 . appended to the end of the section in an unspecified order. *}
274 .#define SEC_SORT_ENTRIES 0x80000
276 . {* When linking, duplicate sections of the same name should be
277 . discarded, rather than being combined into a single section as
278 . is usually done. This is similar to how common symbols are
279 . handled. See SEC_LINK_DUPLICATES below. *}
280 .#define SEC_LINK_ONCE 0x100000
282 . {* If SEC_LINK_ONCE is set, this bitfield describes how the linker
283 . should handle duplicate sections. *}
284 .#define SEC_LINK_DUPLICATES 0x600000
286 . {* This value for SEC_LINK_DUPLICATES means that duplicate
287 . sections with the same name should simply be discarded. *}
288 .#define SEC_LINK_DUPLICATES_DISCARD 0x0
290 . {* This value for SEC_LINK_DUPLICATES means that the linker
291 . should warn if there are any duplicate sections, although
292 . it should still only link one copy. *}
293 .#define SEC_LINK_DUPLICATES_ONE_ONLY 0x200000
295 . {* This value for SEC_LINK_DUPLICATES means that the linker
296 . should warn if any duplicate sections are a different size. *}
297 .#define SEC_LINK_DUPLICATES_SAME_SIZE 0x400000
299 . {* This value for SEC_LINK_DUPLICATES means that the linker
300 . should warn if any duplicate sections contain different
301 . contents. *}
302 .#define SEC_LINK_DUPLICATES_SAME_CONTENTS 0x600000
304 . {* This section was created by the linker as part of dynamic
305 . relocation or other arcane processing. It is skipped when
306 . going through the first-pass output, trusting that someone
307 . else up the line will take care of it later. *}
308 .#define SEC_LINKER_CREATED 0x800000
310 . {* This section should not be subject to garbage collection. *}
311 .#define SEC_KEEP 0x1000000
313 . {* This section contains "short" data, and should be placed
314 . "near" the GP. *}
315 .#define SEC_SMALL_DATA 0x2000000
317 . {* This section contains data which may be shared with other
318 . executables or shared objects. *}
319 .#define SEC_SHARED 0x4000000
321 . {* When a section with this flag is being linked, then if the size of
322 . the input section is less than a page, it should not cross a page
323 . boundary. If the size of the input section is one page or more, it
324 . should be aligned on a page boundary. *}
325 .#define SEC_BLOCK 0x8000000
327 . {* Conditionally link this section; do not link if there are no
328 . references found to any symbol in the section. *}
329 .#define SEC_CLINK 0x10000000
331 . {* Attempt to merge identical entities in the section.
332 . Entity size is given in the entsize field. *}
333 .#define SEC_MERGE 0x20000000
335 . {* If given with SEC_MERGE, entities to merge are zero terminated
336 . strings where entsize specifies character size instead of fixed
337 . size entries. *}
338 .#define SEC_STRINGS 0x40000000
340 . {* This section contains data about section groups. *}
341 .#define SEC_GROUP 0x80000000
343 . {* End of section flags. *}
345 . {* Some internal packed boolean fields. *}
347 . {* See the vma field. *}
348 . unsigned int user_set_vma : 1;
350 . {* A mark flag used by some of the linker backends. *}
351 . unsigned int linker_mark : 1;
353 . {* Another mark flag used by some of the linker backends. Set for
354 . output sections that have an input section. *}
355 . unsigned int linker_has_input : 1;
357 . {* A mark flag used by some linker backends for garbage collection. *}
358 . unsigned int gc_mark : 1;
360 . {* The following flags are used by the ELF linker. *}
362 . {* Mark sections which have been allocated to segments. *}
363 . unsigned int segment_mark : 1;
365 . {* Type of sec_info information. *}
366 . unsigned int sec_info_type:3;
367 .#define ELF_INFO_TYPE_NONE 0
368 .#define ELF_INFO_TYPE_STABS 1
369 .#define ELF_INFO_TYPE_MERGE 2
370 .#define ELF_INFO_TYPE_EH_FRAME 3
371 .#define ELF_INFO_TYPE_JUST_SYMS 4
373 . {* Nonzero if this section uses RELA relocations, rather than REL. *}
374 . unsigned int use_rela_p:1;
376 . {* Bits used by various backends. *}
378 . {* Nonzero if this section has TLS related relocations. *}
379 . unsigned int has_tls_reloc:1;
381 . {* Nonzero if this section has a gp reloc. *}
382 . unsigned int has_gp_reloc:1;
384 . {* Nonzero if this section needs the relax finalize pass. *}
385 . unsigned int need_finalize_relax:1;
387 . {* Whether relocations have been processed. *}
388 . unsigned int reloc_done : 1;
390 . {* End of internal packed boolean fields. *}
392 . {* The virtual memory address of the section - where it will be
393 . at run time. The symbols are relocated against this. The
394 . user_set_vma flag is maintained by bfd; if it's not set, the
395 . backend can assign addresses (for example, in <<a.out>>, where
396 . the default address for <<.data>> is dependent on the specific
397 . target and various flags). *}
398 . bfd_vma vma;
400 . {* The load address of the section - where it would be in a
401 . rom image; really only used for writing section header
402 . information. *}
403 . bfd_vma lma;
405 . {* The size of the section in octets, as it will be output.
406 . Contains a value even if the section has no contents (e.g., the
407 . size of <<.bss>>). *}
408 . bfd_size_type size;
410 . {* For input sections, the original size on disk of the section, in
411 . octets. This field is used by the linker relaxation code. It is
412 . currently only set for sections where the linker relaxation scheme
413 . doesn't cache altered section and reloc contents (stabs, eh_frame,
414 . SEC_MERGE, some coff relaxing targets), and thus the original size
415 . needs to be kept to read the section multiple times.
416 . For output sections, rawsize holds the section size calculated on
417 . a previous linker relaxation pass. *}
418 . bfd_size_type rawsize;
420 . {* If this section is going to be output, then this value is the
421 . offset in *bytes* into the output section of the first byte in the
422 . input section (byte ==> smallest addressable unit on the
423 . target). In most cases, if this was going to start at the
424 . 100th octet (8-bit quantity) in the output section, this value
425 . would be 100. However, if the target byte size is 16 bits
426 . (bfd_octets_per_byte is "2"), this value would be 50. *}
427 . bfd_vma output_offset;
429 . {* The output section through which to map on output. *}
430 . struct bfd_section *output_section;
432 . {* The alignment requirement of the section, as an exponent of 2 -
433 . e.g., 3 aligns to 2^3 (or 8). *}
434 . unsigned int alignment_power;
436 . {* If an input section, a pointer to a vector of relocation
437 . records for the data in this section. *}
438 . struct reloc_cache_entry *relocation;
440 . {* If an output section, a pointer to a vector of pointers to
441 . relocation records for the data in this section. *}
442 . struct reloc_cache_entry **orelocation;
444 . {* The number of relocation records in one of the above. *}
445 . unsigned reloc_count;
447 . {* Information below is back end specific - and not always used
448 . or updated. *}
450 . {* File position of section data. *}
451 . file_ptr filepos;
453 . {* File position of relocation info. *}
454 . file_ptr rel_filepos;
456 . {* File position of line data. *}
457 . file_ptr line_filepos;
459 . {* Pointer to data for applications. *}
460 . void *userdata;
462 . {* If the SEC_IN_MEMORY flag is set, this points to the actual
463 . contents. *}
464 . unsigned char *contents;
466 . {* Attached line number information. *}
467 . alent *lineno;
469 . {* Number of line number records. *}
470 . unsigned int lineno_count;
472 . {* Entity size for merging purposes. *}
473 . unsigned int entsize;
475 . {* Points to the kept section if this section is a link-once section,
476 . and is discarded. *}
477 . struct bfd_section *kept_section;
479 . {* When a section is being output, this value changes as more
480 . linenumbers are written out. *}
481 . file_ptr moving_line_filepos;
483 . {* What the section number is in the target world. *}
484 . int target_index;
486 . void *used_by_bfd;
488 . {* If this is a constructor section then here is a list of the
489 . relocations created to relocate items within it. *}
490 . struct relent_chain *constructor_chain;
492 . {* The BFD which owns the section. *}
493 . bfd *owner;
495 . {* A symbol which points at this section only. *}
496 . struct bfd_symbol *symbol;
497 . struct bfd_symbol **symbol_ptr_ptr;
499 . struct bfd_link_order *link_order_head;
500 . struct bfd_link_order *link_order_tail;
501 .} asection;
503 .{* These sections are global, and are managed by BFD. The application
504 . and target back end are not permitted to change the values in
505 . these sections. New code should use the section_ptr macros rather
506 . than referring directly to the const sections. The const sections
507 . may eventually vanish. *}
508 .#define BFD_ABS_SECTION_NAME "*ABS*"
509 .#define BFD_UND_SECTION_NAME "*UND*"
510 .#define BFD_COM_SECTION_NAME "*COM*"
511 .#define BFD_IND_SECTION_NAME "*IND*"
513 .{* The absolute section. *}
514 .extern asection bfd_abs_section;
515 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
516 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
517 .{* Pointer to the undefined section. *}
518 .extern asection bfd_und_section;
519 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
520 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
521 .{* Pointer to the common section. *}
522 .extern asection bfd_com_section;
523 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
524 .{* Pointer to the indirect section. *}
525 .extern asection bfd_ind_section;
526 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
527 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
529 .#define bfd_is_const_section(SEC) \
530 . ( ((SEC) == bfd_abs_section_ptr) \
531 . || ((SEC) == bfd_und_section_ptr) \
532 . || ((SEC) == bfd_com_section_ptr) \
533 . || ((SEC) == bfd_ind_section_ptr))
535 .extern const struct bfd_symbol * const bfd_abs_symbol;
536 .extern const struct bfd_symbol * const bfd_com_symbol;
537 .extern const struct bfd_symbol * const bfd_und_symbol;
538 .extern const struct bfd_symbol * const bfd_ind_symbol;
540 .{* Macros to handle insertion and deletion of a bfd's sections. These
541 . only handle the list pointers, ie. do not adjust section_count,
542 . target_index etc. *}
543 .#define bfd_section_list_remove(ABFD, PS) \
544 . do \
545 . { \
546 . asection **_ps = PS; \
547 . asection *_s = *_ps; \
548 . *_ps = _s->next; \
549 . if (_s->next == NULL) \
550 . (ABFD)->section_tail = _ps; \
551 . } \
552 . while (0)
553 .#define bfd_section_list_insert(ABFD, PS, S) \
554 . do \
555 . { \
556 . asection **_ps = PS; \
557 . asection *_s = S; \
558 . _s->next = *_ps; \
559 . *_ps = _s; \
560 . if (_s->next == NULL) \
561 . (ABFD)->section_tail = &_s->next; \
562 . } \
563 . while (0)
567 /* We use a macro to initialize the static asymbol structures because
568 traditional C does not permit us to initialize a union member while
569 gcc warns if we don't initialize it. */
570 /* the_bfd, name, value, attr, section [, udata] */
571 #ifdef __STDC__
572 #define GLOBAL_SYM_INIT(NAME, SECTION) \
573 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION, { 0 }}
574 #else
575 #define GLOBAL_SYM_INIT(NAME, SECTION) \
576 { 0, NAME, 0, BSF_SECTION_SYM, (asection *) SECTION }
577 #endif
579 /* These symbols are global, not specific to any BFD. Therefore, anything
580 that tries to change them is broken, and should be repaired. */
582 static const asymbol global_syms[] =
584 GLOBAL_SYM_INIT (BFD_COM_SECTION_NAME, &bfd_com_section),
585 GLOBAL_SYM_INIT (BFD_UND_SECTION_NAME, &bfd_und_section),
586 GLOBAL_SYM_INIT (BFD_ABS_SECTION_NAME, &bfd_abs_section),
587 GLOBAL_SYM_INIT (BFD_IND_SECTION_NAME, &bfd_ind_section)
590 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
591 const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
592 asection SEC = \
593 /* name, id, index, next, flags, user_set_vma, */ \
594 { NAME, IDX, 0, NULL, FLAGS, 0, \
596 /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \
597 0, 0, 1, 0, \
599 /* sec_info_type, use_rela_p, has_tls_reloc, has_gp_reloc, */ \
600 0, 0, 0, 0, \
602 /* need_finalize_relax, reloc_done, */ \
603 0, 0, \
605 /* vma, lma, size, rawsize */ \
606 0, 0, 0, 0, \
608 /* output_offset, output_section, alignment_power, */ \
609 0, (struct bfd_section *) &SEC, 0, \
611 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
612 NULL, NULL, 0, 0, 0, \
614 /* line_filepos, userdata, contents, lineno, lineno_count, */ \
615 0, NULL, NULL, NULL, 0, \
617 /* entsize, kept_section, moving_line_filepos, */ \
618 0, NULL, 0, \
620 /* target_index, used_by_bfd, constructor_chain, owner, */ \
621 0, NULL, NULL, NULL, \
623 /* symbol, */ \
624 (struct bfd_symbol *) &global_syms[IDX], \
626 /* symbol_ptr_ptr, */ \
627 (struct bfd_symbol **) &SYM, \
629 /* link_order_head, link_order_tail */ \
630 NULL, NULL \
633 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
634 BFD_COM_SECTION_NAME, 0);
635 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
636 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
637 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
638 #undef STD_SECTION
640 struct section_hash_entry
642 struct bfd_hash_entry root;
643 asection section;
646 /* Initialize an entry in the section hash table. */
648 struct bfd_hash_entry *
649 bfd_section_hash_newfunc (struct bfd_hash_entry *entry,
650 struct bfd_hash_table *table,
651 const char *string)
653 /* Allocate the structure if it has not already been allocated by a
654 subclass. */
655 if (entry == NULL)
657 entry = (struct bfd_hash_entry *)
658 bfd_hash_allocate (table, sizeof (struct section_hash_entry));
659 if (entry == NULL)
660 return entry;
663 /* Call the allocation method of the superclass. */
664 entry = bfd_hash_newfunc (entry, table, string);
665 if (entry != NULL)
666 memset (&((struct section_hash_entry *) entry)->section, 0,
667 sizeof (asection));
669 return entry;
672 #define section_hash_lookup(table, string, create, copy) \
673 ((struct section_hash_entry *) \
674 bfd_hash_lookup ((table), (string), (create), (copy)))
676 /* Initializes a new section. NEWSECT->NAME is already set. */
678 static asection *
679 bfd_section_init (bfd *abfd, asection *newsect)
681 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */
683 newsect->id = section_id;
684 newsect->index = abfd->section_count;
685 newsect->owner = abfd;
687 /* Create a symbol whose only job is to point to this section. This
688 is useful for things like relocs which are relative to the base
689 of a section. */
690 newsect->symbol = bfd_make_empty_symbol (abfd);
691 if (newsect->symbol == NULL)
692 return NULL;
694 newsect->symbol->name = newsect->name;
695 newsect->symbol->value = 0;
696 newsect->symbol->section = newsect;
697 newsect->symbol->flags = BSF_SECTION_SYM;
699 newsect->symbol_ptr_ptr = &newsect->symbol;
701 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect)))
702 return NULL;
704 section_id++;
705 abfd->section_count++;
706 *abfd->section_tail = newsect;
707 abfd->section_tail = &newsect->next;
708 return newsect;
712 DOCDD
713 INODE
714 section prototypes, , typedef asection, Sections
715 SUBSECTION
716 Section prototypes
718 These are the functions exported by the section handling part of BFD.
722 FUNCTION
723 bfd_section_list_clear
725 SYNOPSIS
726 void bfd_section_list_clear (bfd *);
728 DESCRIPTION
729 Clears the section list, and also resets the section count and
730 hash table entries.
733 void
734 bfd_section_list_clear (bfd *abfd)
736 abfd->sections = NULL;
737 abfd->section_tail = &abfd->sections;
738 abfd->section_count = 0;
739 memset (abfd->section_htab.table, 0,
740 abfd->section_htab.size * sizeof (struct bfd_hash_entry *));
744 FUNCTION
745 bfd_get_section_by_name
747 SYNOPSIS
748 asection *bfd_get_section_by_name (bfd *abfd, const char *name);
750 DESCRIPTION
751 Run through @var{abfd} and return the one of the
752 <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
753 @xref{Sections}, for more information.
755 This should only be used in special cases; the normal way to process
756 all sections of a given name is to use <<bfd_map_over_sections>> and
757 <<strcmp>> on the name (or better yet, base it on the section flags
758 or something else) for each section.
761 asection *
762 bfd_get_section_by_name (bfd *abfd, const char *name)
764 struct section_hash_entry *sh;
766 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
767 if (sh != NULL)
768 return &sh->section;
770 return NULL;
774 FUNCTION
775 bfd_get_section_by_name_if
777 SYNOPSIS
778 asection *bfd_get_section_by_name_if
779 (bfd *abfd,
780 const char *name,
781 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),
782 void *obj);
784 DESCRIPTION
785 Call the provided function @var{func} for each section
786 attached to the BFD @var{abfd} whose name matches @var{name},
787 passing @var{obj} as an argument. The function will be called
788 as if by
790 | func (abfd, the_section, obj);
792 It returns the first section for which @var{func} returns true,
793 otherwise <<NULL>>.
797 asection *
798 bfd_get_section_by_name_if (bfd *abfd, const char *name,
799 bfd_boolean (*operation) (bfd *,
800 asection *,
801 void *),
802 void *user_storage)
804 struct section_hash_entry *sh;
805 unsigned long hash;
807 sh = section_hash_lookup (&abfd->section_htab, name, FALSE, FALSE);
808 if (sh == NULL)
809 return NULL;
811 hash = sh->root.hash;
814 if ((*operation) (abfd, &sh->section, user_storage))
815 return &sh->section;
816 sh = (struct section_hash_entry *) sh->root.next;
818 while (sh != NULL && sh->root.hash == hash
819 && strcmp (sh->root.string, name) == 0);
821 return NULL;
825 FUNCTION
826 bfd_get_unique_section_name
828 SYNOPSIS
829 char *bfd_get_unique_section_name
830 (bfd *abfd, const char *templat, int *count);
832 DESCRIPTION
833 Invent a section name that is unique in @var{abfd} by tacking
834 a dot and a digit suffix onto the original @var{templat}. If
835 @var{count} is non-NULL, then it specifies the first number
836 tried as a suffix to generate a unique name. The value
837 pointed to by @var{count} will be incremented in this case.
840 char *
841 bfd_get_unique_section_name (bfd *abfd, const char *templat, int *count)
843 int num;
844 unsigned int len;
845 char *sname;
847 len = strlen (templat);
848 sname = bfd_malloc (len + 8);
849 if (sname == NULL)
850 return NULL;
851 memcpy (sname, templat, len);
852 num = 1;
853 if (count != NULL)
854 num = *count;
858 /* If we have a million sections, something is badly wrong. */
859 if (num > 999999)
860 abort ();
861 sprintf (sname + len, ".%d", num++);
863 while (section_hash_lookup (&abfd->section_htab, sname, FALSE, FALSE));
865 if (count != NULL)
866 *count = num;
867 return sname;
871 FUNCTION
872 bfd_make_section_old_way
874 SYNOPSIS
875 asection *bfd_make_section_old_way (bfd *abfd, const char *name);
877 DESCRIPTION
878 Create a new empty section called @var{name}
879 and attach it to the end of the chain of sections for the
880 BFD @var{abfd}. An attempt to create a section with a name which
881 is already in use returns its pointer without changing the
882 section chain.
884 It has the funny name since this is the way it used to be
885 before it was rewritten....
887 Possible errors are:
888 o <<bfd_error_invalid_operation>> -
889 If output has already started for this BFD.
890 o <<bfd_error_no_memory>> -
891 If memory allocation fails.
895 asection *
896 bfd_make_section_old_way (bfd *abfd, const char *name)
898 struct section_hash_entry *sh;
899 asection *newsect;
901 if (abfd->output_has_begun)
903 bfd_set_error (bfd_error_invalid_operation);
904 return NULL;
907 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
908 return bfd_abs_section_ptr;
910 if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
911 return bfd_com_section_ptr;
913 if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
914 return bfd_und_section_ptr;
916 if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
917 return bfd_ind_section_ptr;
919 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
920 if (sh == NULL)
921 return NULL;
923 newsect = &sh->section;
924 if (newsect->name != NULL)
926 /* Section already exists. */
927 return newsect;
930 newsect->name = name;
931 return bfd_section_init (abfd, newsect);
935 FUNCTION
936 bfd_make_section_anyway
938 SYNOPSIS
939 asection *bfd_make_section_anyway (bfd *abfd, const char *name);
941 DESCRIPTION
942 Create a new empty section called @var{name} and attach it to the end of
943 the chain of sections for @var{abfd}. Create a new section even if there
944 is already a section with that name.
946 Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
947 o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
948 o <<bfd_error_no_memory>> - If memory allocation fails.
951 sec_ptr
952 bfd_make_section_anyway (bfd *abfd, const char *name)
954 struct section_hash_entry *sh;
955 asection *newsect;
957 if (abfd->output_has_begun)
959 bfd_set_error (bfd_error_invalid_operation);
960 return NULL;
963 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
964 if (sh == NULL)
965 return NULL;
967 newsect = &sh->section;
968 if (newsect->name != NULL)
970 /* We are making a section of the same name. Put it in the
971 section hash table. Even though we can't find it directly by a
972 hash lookup, we'll be able to find the section by traversing
973 sh->root.next quicker than looking at all the bfd sections. */
974 struct section_hash_entry *new_sh;
975 new_sh = (struct section_hash_entry *)
976 bfd_section_hash_newfunc (NULL, &abfd->section_htab, name);
977 if (new_sh == NULL)
978 return NULL;
980 new_sh->root = sh->root;
981 sh->root.next = &new_sh->root;
982 newsect = &new_sh->section;
985 newsect->name = name;
986 return bfd_section_init (abfd, newsect);
990 FUNCTION
991 bfd_make_section
993 SYNOPSIS
994 asection *bfd_make_section (bfd *, const char *name);
996 DESCRIPTION
997 Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
998 bfd_set_error ()) without changing the section chain if there is already a
999 section named @var{name}. If there is an error, return <<NULL>> and set
1000 <<bfd_error>>.
1003 asection *
1004 bfd_make_section (bfd *abfd, const char *name)
1006 struct section_hash_entry *sh;
1007 asection *newsect;
1009 if (abfd->output_has_begun)
1011 bfd_set_error (bfd_error_invalid_operation);
1012 return NULL;
1015 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0
1016 || strcmp (name, BFD_COM_SECTION_NAME) == 0
1017 || strcmp (name, BFD_UND_SECTION_NAME) == 0
1018 || strcmp (name, BFD_IND_SECTION_NAME) == 0)
1019 return NULL;
1021 sh = section_hash_lookup (&abfd->section_htab, name, TRUE, FALSE);
1022 if (sh == NULL)
1023 return NULL;
1025 newsect = &sh->section;
1026 if (newsect->name != NULL)
1028 /* Section already exists. */
1029 return NULL;
1032 newsect->name = name;
1033 return bfd_section_init (abfd, newsect);
1037 FUNCTION
1038 bfd_set_section_flags
1040 SYNOPSIS
1041 bfd_boolean bfd_set_section_flags
1042 (bfd *abfd, asection *sec, flagword flags);
1044 DESCRIPTION
1045 Set the attributes of the section @var{sec} in the BFD
1046 @var{abfd} to the value @var{flags}. Return <<TRUE>> on success,
1047 <<FALSE>> on error. Possible error returns are:
1049 o <<bfd_error_invalid_operation>> -
1050 The section cannot have one or more of the attributes
1051 requested. For example, a .bss section in <<a.out>> may not
1052 have the <<SEC_HAS_CONTENTS>> field set.
1056 bfd_boolean
1057 bfd_set_section_flags (bfd *abfd ATTRIBUTE_UNUSED,
1058 sec_ptr section,
1059 flagword flags)
1061 #if 0
1062 /* If you try to copy a text section from an input file (where it
1063 has the SEC_CODE flag set) to an output file, this loses big if
1064 the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
1065 set - which it doesn't, at least not for a.out. FIXME */
1067 if ((flags & bfd_applicable_section_flags (abfd)) != flags)
1069 bfd_set_error (bfd_error_invalid_operation);
1070 return FALSE;
1072 #endif
1074 section->flags = flags;
1075 return TRUE;
1079 FUNCTION
1080 bfd_map_over_sections
1082 SYNOPSIS
1083 void bfd_map_over_sections
1084 (bfd *abfd,
1085 void (*func) (bfd *abfd, asection *sect, void *obj),
1086 void *obj);
1088 DESCRIPTION
1089 Call the provided function @var{func} for each section
1090 attached to the BFD @var{abfd}, passing @var{obj} as an
1091 argument. The function will be called as if by
1093 | func (abfd, the_section, obj);
1095 This is the preferred method for iterating over sections; an
1096 alternative would be to use a loop:
1098 | section *p;
1099 | for (p = abfd->sections; p != NULL; p = p->next)
1100 | func (abfd, p, ...)
1104 void
1105 bfd_map_over_sections (bfd *abfd,
1106 void (*operation) (bfd *, asection *, void *),
1107 void *user_storage)
1109 asection *sect;
1110 unsigned int i = 0;
1112 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
1113 (*operation) (abfd, sect, user_storage);
1115 if (i != abfd->section_count) /* Debugging */
1116 abort ();
1120 FUNCTION
1121 bfd_sections_find_if
1123 SYNOPSIS
1124 asection *bfd_sections_find_if
1125 (bfd *abfd,
1126 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),
1127 void *obj);
1129 DESCRIPTION
1130 Call the provided function @var{func} for each section
1131 attached to the BFD @var{abfd}, passing @var{obj} as an
1132 argument. The function will be called as if by
1134 | func (abfd, the_section, obj);
1136 It returns the first section for which @var{func} returns true.
1140 asection *
1141 bfd_sections_find_if (bfd *abfd,
1142 bfd_boolean (*operation) (bfd *, asection *, void *),
1143 void *user_storage)
1145 asection *sect;
1147 for (sect = abfd->sections; sect != NULL; sect = sect->next)
1148 if ((*operation) (abfd, sect, user_storage))
1149 break;
1151 return sect;
1155 FUNCTION
1156 bfd_set_section_size
1158 SYNOPSIS
1159 bfd_boolean bfd_set_section_size
1160 (bfd *abfd, asection *sec, bfd_size_type val);
1162 DESCRIPTION
1163 Set @var{sec} to the size @var{val}. If the operation is
1164 ok, then <<TRUE>> is returned, else <<FALSE>>.
1166 Possible error returns:
1167 o <<bfd_error_invalid_operation>> -
1168 Writing has started to the BFD, so setting the size is invalid.
1172 bfd_boolean
1173 bfd_set_section_size (bfd *abfd, sec_ptr ptr, bfd_size_type val)
1175 /* Once you've started writing to any section you cannot create or change
1176 the size of any others. */
1178 if (abfd->output_has_begun)
1180 bfd_set_error (bfd_error_invalid_operation);
1181 return FALSE;
1184 ptr->size = val;
1185 return TRUE;
1189 FUNCTION
1190 bfd_set_section_contents
1192 SYNOPSIS
1193 bfd_boolean bfd_set_section_contents
1194 (bfd *abfd, asection *section, const void *data,
1195 file_ptr offset, bfd_size_type count);
1197 DESCRIPTION
1198 Sets the contents of the section @var{section} in BFD
1199 @var{abfd} to the data starting in memory at @var{data}. The
1200 data is written to the output section starting at offset
1201 @var{offset} for @var{count} octets.
1203 Normally <<TRUE>> is returned, else <<FALSE>>. Possible error
1204 returns are:
1205 o <<bfd_error_no_contents>> -
1206 The output section does not have the <<SEC_HAS_CONTENTS>>
1207 attribute, so nothing can be written to it.
1208 o and some more too
1210 This routine is front end to the back end function
1211 <<_bfd_set_section_contents>>.
1215 bfd_boolean
1216 bfd_set_section_contents (bfd *abfd,
1217 sec_ptr section,
1218 const void *location,
1219 file_ptr offset,
1220 bfd_size_type count)
1222 bfd_size_type sz;
1224 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
1226 bfd_set_error (bfd_error_no_contents);
1227 return FALSE;
1230 sz = section->size;
1231 if ((bfd_size_type) offset > sz
1232 || count > sz
1233 || offset + count > sz
1234 || count != (size_t) count)
1236 bfd_set_error (bfd_error_bad_value);
1237 return FALSE;
1240 switch (abfd->direction)
1242 case read_direction:
1243 case no_direction:
1244 bfd_set_error (bfd_error_invalid_operation);
1245 return FALSE;
1247 case write_direction:
1248 break;
1250 case both_direction:
1251 /* File is opened for update. `output_has_begun' some time ago when
1252 the file was created. Do not recompute sections sizes or alignments
1253 in _bfd_set_section_content. */
1254 abfd->output_has_begun = TRUE;
1255 break;
1258 /* Record a copy of the data in memory if desired. */
1259 if (section->contents
1260 && location != section->contents + offset)
1261 memcpy (section->contents + offset, location, (size_t) count);
1263 if (BFD_SEND (abfd, _bfd_set_section_contents,
1264 (abfd, section, location, offset, count)))
1266 abfd->output_has_begun = TRUE;
1267 return TRUE;
1270 return FALSE;
1274 FUNCTION
1275 bfd_get_section_contents
1277 SYNOPSIS
1278 bfd_boolean bfd_get_section_contents
1279 (bfd *abfd, asection *section, void *location, file_ptr offset,
1280 bfd_size_type count);
1282 DESCRIPTION
1283 Read data from @var{section} in BFD @var{abfd}
1284 into memory starting at @var{location}. The data is read at an
1285 offset of @var{offset} from the start of the input section,
1286 and is read for @var{count} bytes.
1288 If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
1289 flag set are requested or if the section does not have the
1290 <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
1291 with zeroes. If no errors occur, <<TRUE>> is returned, else
1292 <<FALSE>>.
1295 bfd_boolean
1296 bfd_get_section_contents (bfd *abfd,
1297 sec_ptr section,
1298 void *location,
1299 file_ptr offset,
1300 bfd_size_type count)
1302 bfd_size_type sz;
1304 if (section->flags & SEC_CONSTRUCTOR)
1306 memset (location, 0, (size_t) count);
1307 return TRUE;
1310 sz = section->rawsize ? section->rawsize : section->size;
1311 if ((bfd_size_type) offset > sz
1312 || count > sz
1313 || offset + count > sz
1314 || count != (size_t) count)
1316 bfd_set_error (bfd_error_bad_value);
1317 return FALSE;
1320 if (count == 0)
1321 /* Don't bother. */
1322 return TRUE;
1324 if ((section->flags & SEC_HAS_CONTENTS) == 0)
1326 memset (location, 0, (size_t) count);
1327 return TRUE;
1330 if ((section->flags & SEC_IN_MEMORY) != 0)
1332 memcpy (location, section->contents + offset, (size_t) count);
1333 return TRUE;
1336 return BFD_SEND (abfd, _bfd_get_section_contents,
1337 (abfd, section, location, offset, count));
1341 FUNCTION
1342 bfd_malloc_and_get_section
1344 SYNOPSIS
1345 bfd_boolean bfd_malloc_and_get_section
1346 (bfd *abfd, asection *section, bfd_byte **buf);
1348 DESCRIPTION
1349 Read all data from @var{section} in BFD @var{abfd}
1350 into a buffer, *@var{buf}, malloc'd by this function.
1353 bfd_boolean
1354 bfd_malloc_and_get_section (bfd *abfd, sec_ptr sec, bfd_byte **buf)
1356 bfd_size_type sz = sec->rawsize ? sec->rawsize : sec->size;
1357 bfd_byte *p = NULL;
1359 *buf = p;
1360 if (sz == 0)
1361 return TRUE;
1363 p = bfd_malloc (sec->rawsize > sec->size ? sec->rawsize : sec->size);
1364 if (p == NULL)
1365 return FALSE;
1366 *buf = p;
1368 return bfd_get_section_contents (abfd, sec, p, 0, sz);
1371 FUNCTION
1372 bfd_copy_private_section_data
1374 SYNOPSIS
1375 bfd_boolean bfd_copy_private_section_data
1376 (bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
1378 DESCRIPTION
1379 Copy private section information from @var{isec} in the BFD
1380 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1381 Return <<TRUE>> on success, <<FALSE>> on error. Possible error
1382 returns are:
1384 o <<bfd_error_no_memory>> -
1385 Not enough memory exists to create private data for @var{osec}.
1387 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1388 . BFD_SEND (obfd, _bfd_copy_private_section_data, \
1389 . (ibfd, isection, obfd, osection))
1393 FUNCTION
1394 _bfd_strip_section_from_output
1396 SYNOPSIS
1397 void _bfd_strip_section_from_output
1398 (struct bfd_link_info *info, asection *section);
1400 DESCRIPTION
1401 Remove @var{section} from the output. If the output section
1402 becomes empty, remove it from the output bfd.
1404 This function won't actually do anything except twiddle flags
1405 if called too late in the linking process, when it's not safe
1406 to remove sections.
1408 void
1409 _bfd_strip_section_from_output (struct bfd_link_info *info, asection *s)
1411 asection *os;
1412 asection *is;
1413 bfd *abfd;
1415 s->flags |= SEC_EXCLUDE;
1417 /* If the section wasn't assigned to an output section, or the
1418 section has been discarded by the linker script, there's nothing
1419 more to do. */
1420 os = s->output_section;
1421 if (os == NULL || os->owner == NULL)
1422 return;
1424 /* If the output section has other (non-excluded) input sections, we
1425 can't remove it. */
1426 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
1427 for (is = abfd->sections; is != NULL; is = is->next)
1428 if (is->output_section == os && (is->flags & SEC_EXCLUDE) == 0)
1429 return;
1431 /* If the output section is empty, flag it for removal too.
1432 See ldlang.c:strip_excluded_output_sections for the action. */
1433 os->flags |= SEC_EXCLUDE;
1437 FUNCTION
1438 bfd_generic_is_group_section
1440 SYNOPSIS
1441 bfd_boolean bfd_generic_is_group_section (bfd *, const asection *sec);
1443 DESCRIPTION
1444 Returns TRUE if @var{sec} is a member of a group.
1447 bfd_boolean
1448 bfd_generic_is_group_section (bfd *abfd ATTRIBUTE_UNUSED,
1449 const asection *sec ATTRIBUTE_UNUSED)
1451 return FALSE;
1455 FUNCTION
1456 bfd_generic_discard_group
1458 SYNOPSIS
1459 bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group);
1461 DESCRIPTION
1462 Remove all members of @var{group} from the output.
1465 bfd_boolean
1466 bfd_generic_discard_group (bfd *abfd ATTRIBUTE_UNUSED,
1467 asection *group ATTRIBUTE_UNUSED)
1469 return TRUE;