section.texi revision 1.1.1.2
1@section Sections 2The raw data contained within a BFD is maintained through the 3section abstraction. A single BFD may have any number of 4sections. It keeps hold of them by pointing to the first; 5each one points to the next in the list. 6 7Sections are supported in BFD in @code{section.c}. 8 9@menu 10* Section Input:: 11* Section Output:: 12* typedef asection:: 13* section prototypes:: 14@end menu 15 16@node Section Input, Section Output, Sections, Sections 17@subsection Section input 18When a BFD is opened for reading, the section structures are 19created and attached to the BFD. 20 21Each section has a name which describes the section in the 22outside world---for example, @code{a.out} would contain at least 23three sections, called @code{.text}, @code{.data} and @code{.bss}. 24 25Names need not be unique; for example a COFF file may have several 26sections named @code{.data}. 27 28Sometimes a BFD will contain more than the ``natural'' number of 29sections. A back end may attach other sections containing 30constructor data, or an application may add a section (using 31@code{bfd_make_section}) to the sections attached to an already open 32BFD. For example, the linker creates an extra section 33@code{COMMON} for each input file's BFD to hold information about 34common storage. 35 36The raw data is not necessarily read in when 37the section descriptor is created. Some targets may leave the 38data in place until a @code{bfd_get_section_contents} call is 39made. Other back ends may read in all the data at once. For 40example, an S-record file has to be read once to determine the 41size of the data. An IEEE-695 file doesn't contain raw data in 42sections, but data and relocation expressions intermixed, so 43the data area has to be parsed to get out the data and 44relocations. 45 46@node Section Output, typedef asection, Section Input, Sections 47@subsection Section output 48To write a new object style BFD, the various sections to be 49written have to be created. They are attached to the BFD in 50the same way as input sections; data is written to the 51sections using @code{bfd_set_section_contents}. 52 53Any program that creates or combines sections (e.g., the assembler 54and linker) must use the @code{asection} fields @code{output_section} and 55@code{output_offset} to indicate the file sections to which each 56section must be written. (If the section is being created from 57scratch, @code{output_section} should probably point to the section 58itself and @code{output_offset} should probably be zero.) 59 60The data to be written comes from input sections attached 61(via @code{output_section} pointers) to 62the output sections. The output section structure can be 63considered a filter for the input section: the output section 64determines the vma of the output data and the name, but the 65input section determines the offset into the output section of 66the data to be written. 67 68E.g., to create a section "O", starting at 0x100, 0x123 long, 69containing two subsections, "A" at offset 0x0 (i.e., at vma 700x100) and "B" at offset 0x20 (i.e., at vma 0x120) the @code{asection} 71structures would look like: 72 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 84 85@subsection Link orders 86The data within a section is stored in a @dfn{link_order}. 87These are much like the fixups in @code{gas}. The link_order 88abstraction allows a section to grow and shrink within itself. 89 90A link_order knows how big it is, and which is the next 91link_order and where the raw data for it is; it also points to 92a list of relocations which apply to it. 93 94The link_order is used by the linker to perform relaxing on 95final code. The compiler creates code which is as big as 96necessary to make it work without relaxing, and the user can 97select whether to relax. Sometimes relaxing takes a lot of 98time. The linker runs around the relocations to see if any 99are attached to data which can be shrunk, if so it does it on 100a link_order by link_order basis. 101 102 103@node typedef asection, section prototypes, Section Output, Sections 104@subsection typedef asection 105Here is the section structure: 106 107 108@example 109 110typedef 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; 115 116 /* A unique sequence number. */ 117 int id; 118 119 /* Which section in the bfd; 0..n-1 as sections are created in a bfd. */ 120 int index; 121 122 /* The next section in the list belonging to the BFD, or NULL. */ 123 struct bfd_section *next; 124 125 /* The previous section in the list belonging to the BFD, or NULL. */ 126 struct bfd_section *prev; 127 128 /* 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; 132 133#define SEC_NO_FLAGS 0x000 134 135 /* 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 138 139 /* 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 142 143 /* The section contains data still to be relocated, so there is 144 some relocation information too. */ 145#define SEC_RELOC 0x004 146 147 /* A signal to the OS that the section contains read only data. */ 148#define SEC_READONLY 0x008 149 150 /* The section contains code only. */ 151#define SEC_CODE 0x010 152 153 /* The section contains data only. */ 154#define SEC_DATA 0x020 155 156 /* The section will reside in ROM. */ 157#define SEC_ROM 0x040 158 159 /* 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 170 171 /* 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 175 176 /* 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 179 180 /* The section contains thread local data. */ 181#define SEC_THREAD_LOCAL 0x400 182 183 /* 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 190 191 /* 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 197 198 /* 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 203 204 /* 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 208 209 /* 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 213 214 /* 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 219 220 /* 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 225 226 /* If SEC_LINK_ONCE is set, this bitfield describes how the linker 227 should handle duplicate sections. */ 228#define SEC_LINK_DUPLICATES 0xc0000 229 230 /* 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 233 234 /* 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 0x40000 238 239 /* 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 0x80000 242 243 /* 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) 248 249 /* 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 0x100000 254 255 /* This section should not be subject to garbage collection. 256 Also set to inform the linker that this section should not be 257 listed in the link map as discarded. */ 258#define SEC_KEEP 0x200000 259 260 /* This section contains "short" data, and should be placed 261 "near" the GP. */ 262#define SEC_SMALL_DATA 0x400000 263 264 /* Attempt to merge identical entities in the section. 265 Entity size is given in the entsize field. */ 266#define SEC_MERGE 0x800000 267 268 /* If given with SEC_MERGE, entities to merge are zero terminated 269 strings where entsize specifies character size instead of fixed 270 size entries. */ 271#define SEC_STRINGS 0x1000000 272 273 /* This section contains data about section groups. */ 274#define SEC_GROUP 0x2000000 275 276 /* The section is a COFF shared library section. This flag is 277 only for the linker. If this type of section appears in 278 the input file, the linker must copy it to the output file 279 without changing the vma or size. FIXME: Although this 280 was originally intended to be general, it really is COFF 281 specific (and the flag was renamed to indicate this). It 282 might be cleaner to have some more general mechanism to 283 allow the back end to control what the linker does with 284 sections. */ 285#define SEC_COFF_SHARED_LIBRARY 0x4000000 286 287 /* This section contains data which may be shared with other 288 executables or shared objects. This is for COFF only. */ 289#define SEC_COFF_SHARED 0x8000000 290 291 /* When a section with this flag is being linked, then if the size of 292 the input section is less than a page, it should not cross a page 293 boundary. If the size of the input section is one page or more, 294 it should be aligned on a page boundary. This is for TI 295 TMS320C54X only. */ 296#define SEC_TIC54X_BLOCK 0x10000000 297 298 /* Conditionally link this section; do not link if there are no 299 references found to any symbol in the section. This is for TI 300 TMS320C54X only. */ 301#define SEC_TIC54X_CLINK 0x20000000 302 303 /* Indicate that section has the no read flag set. This happens 304 when memory read flag isn't set. */ 305#define SEC_COFF_NOREAD 0x40000000 306 307 /* End of section flags. */ 308 309 /* Some internal packed boolean fields. */ 310 311 /* See the vma field. */ 312 unsigned int user_set_vma : 1; 313 314 /* A mark flag used by some of the linker backends. */ 315 unsigned int linker_mark : 1; 316 317 /* Another mark flag used by some of the linker backends. Set for 318 output sections that have an input section. */ 319 unsigned int linker_has_input : 1; 320 321 /* Mark flag used by some linker backends for garbage collection. */ 322 unsigned int gc_mark : 1; 323 324 /* Section compression status. */ 325 unsigned int compress_status : 2; 326#define COMPRESS_SECTION_NONE 0 327#define COMPRESS_SECTION_DONE 1 328#define DECOMPRESS_SECTION_SIZED 2 329 330 /* The following flags are used by the ELF linker. */ 331 332 /* Mark sections which have been allocated to segments. */ 333 unsigned int segment_mark : 1; 334 335 /* Type of sec_info information. */ 336 unsigned int sec_info_type:3; 337#define ELF_INFO_TYPE_NONE 0 338#define ELF_INFO_TYPE_STABS 1 339#define ELF_INFO_TYPE_MERGE 2 340#define ELF_INFO_TYPE_EH_FRAME 3 341#define ELF_INFO_TYPE_JUST_SYMS 4 342 343 /* Nonzero if this section uses RELA relocations, rather than REL. */ 344 unsigned int use_rela_p:1; 345 346 /* Bits used by various backends. The generic code doesn't touch 347 these fields. */ 348 349 unsigned int sec_flg0:1; 350 unsigned int sec_flg1:1; 351 unsigned int sec_flg2:1; 352 unsigned int sec_flg3:1; 353 unsigned int sec_flg4:1; 354 unsigned int sec_flg5:1; 355 356 /* End of internal packed boolean fields. */ 357 358 /* The virtual memory address of the section - where it will be 359 at run time. The symbols are relocated against this. The 360 user_set_vma flag is maintained by bfd; if it's not set, the 361 backend can assign addresses (for example, in @code{a.out}, where 362 the default address for @code{.data} is dependent on the specific 363 target and various flags). */ 364 bfd_vma vma; 365 366 /* The load address of the section - where it would be in a 367 rom image; really only used for writing section header 368 information. */ 369 bfd_vma lma; 370 371 /* The size of the section in octets, as it will be output. 372 Contains a value even if the section has no contents (e.g., the 373 size of @code{.bss}). */ 374 bfd_size_type size; 375 376 /* For input sections, the original size on disk of the section, in 377 octets. This field should be set for any section whose size is 378 changed by linker relaxation. It is required for sections where 379 the linker relaxation scheme doesn't cache altered section and 380 reloc contents (stabs, eh_frame, SEC_MERGE, some coff relaxing 381 targets), and thus the original size needs to be kept to read the 382 section multiple times. For output sections, rawsize holds the 383 section size calculated on a previous linker relaxation pass. */ 384 bfd_size_type rawsize; 385 386 /* The compressed size of the section in octets. */ 387 bfd_size_type compressed_size; 388 389 /* Relaxation table. */ 390 struct relax_table *relax; 391 392 /* Count of used relaxation table entries. */ 393 int relax_count; 394 395 396 /* If this section is going to be output, then this value is the 397 offset in *bytes* into the output section of the first byte in the 398 input section (byte ==> smallest addressable unit on the 399 target). In most cases, if this was going to start at the 400 100th octet (8-bit quantity) in the output section, this value 401 would be 100. However, if the target byte size is 16 bits 402 (bfd_octets_per_byte is "2"), this value would be 50. */ 403 bfd_vma output_offset; 404 405 /* The output section through which to map on output. */ 406 struct bfd_section *output_section; 407 408 /* The alignment requirement of the section, as an exponent of 2 - 409 e.g., 3 aligns to 2^3 (or 8). */ 410 unsigned int alignment_power; 411 412 /* If an input section, a pointer to a vector of relocation 413 records for the data in this section. */ 414 struct reloc_cache_entry *relocation; 415 416 /* If an output section, a pointer to a vector of pointers to 417 relocation records for the data in this section. */ 418 struct reloc_cache_entry **orelocation; 419 420 /* The number of relocation records in one of the above. */ 421 unsigned reloc_count; 422 423 /* Information below is back end specific - and not always used 424 or updated. */ 425 426 /* File position of section data. */ 427 file_ptr filepos; 428 429 /* File position of relocation info. */ 430 file_ptr rel_filepos; 431 432 /* File position of line data. */ 433 file_ptr line_filepos; 434 435 /* Pointer to data for applications. */ 436 void *userdata; 437 438 /* If the SEC_IN_MEMORY flag is set, this points to the actual 439 contents. */ 440 unsigned char *contents; 441 442 /* Attached line number information. */ 443 alent *lineno; 444 445 /* Number of line number records. */ 446 unsigned int lineno_count; 447 448 /* Entity size for merging purposes. */ 449 unsigned int entsize; 450 451 /* Points to the kept section if this section is a link-once section, 452 and is discarded. */ 453 struct bfd_section *kept_section; 454 455 /* When a section is being output, this value changes as more 456 linenumbers are written out. */ 457 file_ptr moving_line_filepos; 458 459 /* What the section number is in the target world. */ 460 int target_index; 461 462 void *used_by_bfd; 463 464 /* If this is a constructor section then here is a list of the 465 relocations created to relocate items within it. */ 466 struct relent_chain *constructor_chain; 467 468 /* The BFD which owns the section. */ 469 bfd *owner; 470 471 /* A symbol which points at this section only. */ 472 struct bfd_symbol *symbol; 473 struct bfd_symbol **symbol_ptr_ptr; 474 475 /* Early in the link process, map_head and map_tail are used to build 476 a list of input sections attached to an output section. Later, 477 output sections use these fields for a list of bfd_link_order 478 structs. */ 479 union @{ 480 struct bfd_link_order *link_order; 481 struct bfd_section *s; 482 @} map_head, map_tail; 483@} asection; 484 485/* Relax table contains information about instructions which can 486 be removed by relaxation -- replacing a long address with a 487 short address. */ 488struct relax_table @{ 489 /* Address where bytes may be deleted. */ 490 bfd_vma addr; 491 492 /* Number of bytes to be deleted. */ 493 int size; 494@}; 495 496/* These sections are global, and are managed by BFD. The application 497 and target back end are not permitted to change the values in 498 these sections. New code should use the section_ptr macros rather 499 than referring directly to the const sections. The const sections 500 may eventually vanish. */ 501#define BFD_ABS_SECTION_NAME "*ABS*" 502#define BFD_UND_SECTION_NAME "*UND*" 503#define BFD_COM_SECTION_NAME "*COM*" 504#define BFD_IND_SECTION_NAME "*IND*" 505 506/* The absolute section. */ 507extern asection bfd_abs_section; 508#define bfd_abs_section_ptr ((asection *) &bfd_abs_section) 509#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr) 510/* Pointer to the undefined section. */ 511extern asection bfd_und_section; 512#define bfd_und_section_ptr ((asection *) &bfd_und_section) 513#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr) 514/* Pointer to the common section. */ 515extern asection bfd_com_section; 516#define bfd_com_section_ptr ((asection *) &bfd_com_section) 517/* Pointer to the indirect section. */ 518extern asection bfd_ind_section; 519#define bfd_ind_section_ptr ((asection *) &bfd_ind_section) 520#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr) 521 522#define bfd_is_const_section(SEC) \ 523 ( ((SEC) == bfd_abs_section_ptr) \ 524 || ((SEC) == bfd_und_section_ptr) \ 525 || ((SEC) == bfd_com_section_ptr) \ 526 || ((SEC) == bfd_ind_section_ptr)) 527 528/* Macros to handle insertion and deletion of a bfd's sections. These 529 only handle the list pointers, ie. do not adjust section_count, 530 target_index etc. */ 531#define bfd_section_list_remove(ABFD, S) \ 532 do \ 533 @{ \ 534 asection *_s = S; \ 535 asection *_next = _s->next; \ 536 asection *_prev = _s->prev; \ 537 if (_prev) \ 538 _prev->next = _next; \ 539 else \ 540 (ABFD)->sections = _next; \ 541 if (_next) \ 542 _next->prev = _prev; \ 543 else \ 544 (ABFD)->section_last = _prev; \ 545 @} \ 546 while (0) 547#define bfd_section_list_append(ABFD, S) \ 548 do \ 549 @{ \ 550 asection *_s = S; \ 551 bfd *_abfd = ABFD; \ 552 _s->next = NULL; \ 553 if (_abfd->section_last) \ 554 @{ \ 555 _s->prev = _abfd->section_last; \ 556 _abfd->section_last->next = _s; \ 557 @} \ 558 else \ 559 @{ \ 560 _s->prev = NULL; \ 561 _abfd->sections = _s; \ 562 @} \ 563 _abfd->section_last = _s; \ 564 @} \ 565 while (0) 566#define bfd_section_list_prepend(ABFD, S) \ 567 do \ 568 @{ \ 569 asection *_s = S; \ 570 bfd *_abfd = ABFD; \ 571 _s->prev = NULL; \ 572 if (_abfd->sections) \ 573 @{ \ 574 _s->next = _abfd->sections; \ 575 _abfd->sections->prev = _s; \ 576 @} \ 577 else \ 578 @{ \ 579 _s->next = NULL; \ 580 _abfd->section_last = _s; \ 581 @} \ 582 _abfd->sections = _s; \ 583 @} \ 584 while (0) 585#define bfd_section_list_insert_after(ABFD, A, S) \ 586 do \ 587 @{ \ 588 asection *_a = A; \ 589 asection *_s = S; \ 590 asection *_next = _a->next; \ 591 _s->next = _next; \ 592 _s->prev = _a; \ 593 _a->next = _s; \ 594 if (_next) \ 595 _next->prev = _s; \ 596 else \ 597 (ABFD)->section_last = _s; \ 598 @} \ 599 while (0) 600#define bfd_section_list_insert_before(ABFD, B, S) \ 601 do \ 602 @{ \ 603 asection *_b = B; \ 604 asection *_s = S; \ 605 asection *_prev = _b->prev; \ 606 _s->prev = _prev; \ 607 _s->next = _b; \ 608 _b->prev = _s; \ 609 if (_prev) \ 610 _prev->next = _s; \ 611 else \ 612 (ABFD)->sections = _s; \ 613 @} \ 614 while (0) 615#define bfd_section_removed_from_list(ABFD, S) \ 616 ((S)->next == NULL ? (ABFD)->section_last != (S) : (S)->next->prev != (S)) 617 618#define BFD_FAKE_SECTION(SEC, FLAGS, SYM, NAME, IDX) \ 619 /* name, id, index, next, prev, flags, user_set_vma, */ \ 620 @{ NAME, IDX, 0, NULL, NULL, FLAGS, 0, \ 621 \ 622 /* linker_mark, linker_has_input, gc_mark, decompress_status, */ \ 623 0, 0, 1, 0, \ 624 \ 625 /* segment_mark, sec_info_type, use_rela_p, */ \ 626 0, 0, 0, \ 627 \ 628 /* sec_flg0, sec_flg1, sec_flg2, sec_flg3, sec_flg4, sec_flg5, */ \ 629 0, 0, 0, 0, 0, 0, \ 630 \ 631 /* vma, lma, size, rawsize, compressed_size, relax, relax_count, */ \ 632 0, 0, 0, 0, 0, 0, 0, \ 633 \ 634 /* output_offset, output_section, alignment_power, */ \ 635 0, (struct bfd_section *) &SEC, 0, \ 636 \ 637 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \ 638 NULL, NULL, 0, 0, 0, \ 639 \ 640 /* line_filepos, userdata, contents, lineno, lineno_count, */ \ 641 0, NULL, NULL, NULL, 0, \ 642 \ 643 /* entsize, kept_section, moving_line_filepos, */ \ 644 0, NULL, 0, \ 645 \ 646 /* target_index, used_by_bfd, constructor_chain, owner, */ \ 647 0, NULL, NULL, NULL, \ 648 \ 649 /* symbol, symbol_ptr_ptr, */ \ 650 (struct bfd_symbol *) SYM, &SEC.symbol, \ 651 \ 652 /* map_head, map_tail */ \ 653 @{ NULL @}, @{ NULL @} \ 654 @} 655 656@end example 657 658@node section prototypes, , typedef asection, Sections 659@subsection Section prototypes 660These are the functions exported by the section handling part of BFD. 661 662@findex bfd_section_list_clear 663@subsubsection @code{bfd_section_list_clear} 664@strong{Synopsis} 665@example 666void bfd_section_list_clear (bfd *); 667@end example 668@strong{Description}@* 669Clears the section list, and also resets the section count and 670hash table entries. 671 672@findex bfd_get_section_by_name 673@subsubsection @code{bfd_get_section_by_name} 674@strong{Synopsis} 675@example 676asection *bfd_get_section_by_name (bfd *abfd, const char *name); 677@end example 678@strong{Description}@* 679Run through @var{abfd} and return the one of the 680@code{asection}s whose name matches @var{name}, otherwise @code{NULL}. 681@xref{Sections}, for more information. 682 683This should only be used in special cases; the normal way to process 684all sections of a given name is to use @code{bfd_map_over_sections} and 685@code{strcmp} on the name (or better yet, base it on the section flags 686or something else) for each section. 687 688@findex bfd_get_section_by_name_if 689@subsubsection @code{bfd_get_section_by_name_if} 690@strong{Synopsis} 691@example 692asection *bfd_get_section_by_name_if 693 (bfd *abfd, 694 const char *name, 695 bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj), 696 void *obj); 697@end example 698@strong{Description}@* 699Call the provided function @var{func} for each section 700attached to the BFD @var{abfd} whose name matches @var{name}, 701passing @var{obj} as an argument. The function will be called 702as if by 703 704@example 705 func (abfd, the_section, obj); 706@end example 707 708It returns the first section for which @var{func} returns true, 709otherwise @code{NULL}. 710 711@findex bfd_get_unique_section_name 712@subsubsection @code{bfd_get_unique_section_name} 713@strong{Synopsis} 714@example 715char *bfd_get_unique_section_name 716 (bfd *abfd, const char *templat, int *count); 717@end example 718@strong{Description}@* 719Invent a section name that is unique in @var{abfd} by tacking 720a dot and a digit suffix onto the original @var{templat}. If 721@var{count} is non-NULL, then it specifies the first number 722tried as a suffix to generate a unique name. The value 723pointed to by @var{count} will be incremented in this case. 724 725@findex bfd_make_section_old_way 726@subsubsection @code{bfd_make_section_old_way} 727@strong{Synopsis} 728@example 729asection *bfd_make_section_old_way (bfd *abfd, const char *name); 730@end example 731@strong{Description}@* 732Create a new empty section called @var{name} 733and attach it to the end of the chain of sections for the 734BFD @var{abfd}. An attempt to create a section with a name which 735is already in use returns its pointer without changing the 736section chain. 737 738It has the funny name since this is the way it used to be 739before it was rewritten.... 740 741Possible errors are: 742@itemize @bullet 743 744@item 745@code{bfd_error_invalid_operation} - 746If output has already started for this BFD. 747@item 748@code{bfd_error_no_memory} - 749If memory allocation fails. 750@end itemize 751 752@findex bfd_make_section_anyway_with_flags 753@subsubsection @code{bfd_make_section_anyway_with_flags} 754@strong{Synopsis} 755@example 756asection *bfd_make_section_anyway_with_flags 757 (bfd *abfd, const char *name, flagword flags); 758@end example 759@strong{Description}@* 760Create a new empty section called @var{name} and attach it to the end of 761the chain of sections for @var{abfd}. Create a new section even if there 762is already a section with that name. Also set the attributes of the 763new section to the value @var{flags}. 764 765Return @code{NULL} and set @code{bfd_error} on error; possible errors are: 766@itemize @bullet 767 768@item 769@code{bfd_error_invalid_operation} - If output has already started for @var{abfd}. 770@item 771@code{bfd_error_no_memory} - If memory allocation fails. 772@end itemize 773 774@findex bfd_make_section_anyway 775@subsubsection @code{bfd_make_section_anyway} 776@strong{Synopsis} 777@example 778asection *bfd_make_section_anyway (bfd *abfd, const char *name); 779@end example 780@strong{Description}@* 781Create a new empty section called @var{name} and attach it to the end of 782the chain of sections for @var{abfd}. Create a new section even if there 783is already a section with that name. 784 785Return @code{NULL} and set @code{bfd_error} on error; possible errors are: 786@itemize @bullet 787 788@item 789@code{bfd_error_invalid_operation} - If output has already started for @var{abfd}. 790@item 791@code{bfd_error_no_memory} - If memory allocation fails. 792@end itemize 793 794@findex bfd_make_section_with_flags 795@subsubsection @code{bfd_make_section_with_flags} 796@strong{Synopsis} 797@example 798asection *bfd_make_section_with_flags 799 (bfd *, const char *name, flagword flags); 800@end example 801@strong{Description}@* 802Like @code{bfd_make_section_anyway}, but return @code{NULL} (without calling 803bfd_set_error ()) without changing the section chain if there is already a 804section named @var{name}. Also set the attributes of the new section to 805the value @var{flags}. If there is an error, return @code{NULL} and set 806@code{bfd_error}. 807 808@findex bfd_make_section 809@subsubsection @code{bfd_make_section} 810@strong{Synopsis} 811@example 812asection *bfd_make_section (bfd *, const char *name); 813@end example 814@strong{Description}@* 815Like @code{bfd_make_section_anyway}, but return @code{NULL} (without calling 816bfd_set_error ()) without changing the section chain if there is already a 817section named @var{name}. If there is an error, return @code{NULL} and set 818@code{bfd_error}. 819 820@findex bfd_set_section_flags 821@subsubsection @code{bfd_set_section_flags} 822@strong{Synopsis} 823@example 824bfd_boolean bfd_set_section_flags 825 (bfd *abfd, asection *sec, flagword flags); 826@end example 827@strong{Description}@* 828Set the attributes of the section @var{sec} in the BFD 829@var{abfd} to the value @var{flags}. Return @code{TRUE} on success, 830@code{FALSE} on error. Possible error returns are: 831 832@itemize @bullet 833 834@item 835@code{bfd_error_invalid_operation} - 836The section cannot have one or more of the attributes 837requested. For example, a .bss section in @code{a.out} may not 838have the @code{SEC_HAS_CONTENTS} field set. 839@end itemize 840 841@findex bfd_rename_section 842@subsubsection @code{bfd_rename_section} 843@strong{Synopsis} 844@example 845void bfd_rename_section 846 (bfd *abfd, asection *sec, const char *newname); 847@end example 848@strong{Description}@* 849Rename section @var{sec} in @var{abfd} to @var{newname}. 850 851@findex bfd_map_over_sections 852@subsubsection @code{bfd_map_over_sections} 853@strong{Synopsis} 854@example 855void bfd_map_over_sections 856 (bfd *abfd, 857 void (*func) (bfd *abfd, asection *sect, void *obj), 858 void *obj); 859@end example 860@strong{Description}@* 861Call the provided function @var{func} for each section 862attached to the BFD @var{abfd}, passing @var{obj} as an 863argument. The function will be called as if by 864 865@example 866 func (abfd, the_section, obj); 867@end example 868 869This is the preferred method for iterating over sections; an 870alternative would be to use a loop: 871 872@example 873 section *p; 874 for (p = abfd->sections; p != NULL; p = p->next) 875 func (abfd, p, ...) 876@end example 877 878@findex bfd_sections_find_if 879@subsubsection @code{bfd_sections_find_if} 880@strong{Synopsis} 881@example 882asection *bfd_sections_find_if 883 (bfd *abfd, 884 bfd_boolean (*operation) (bfd *abfd, asection *sect, void *obj), 885 void *obj); 886@end example 887@strong{Description}@* 888Call the provided function @var{operation} for each section 889attached to the BFD @var{abfd}, passing @var{obj} as an 890argument. The function will be called as if by 891 892@example 893 operation (abfd, the_section, obj); 894@end example 895 896It returns the first section for which @var{operation} returns true. 897 898@findex bfd_set_section_size 899@subsubsection @code{bfd_set_section_size} 900@strong{Synopsis} 901@example 902bfd_boolean bfd_set_section_size 903 (bfd *abfd, asection *sec, bfd_size_type val); 904@end example 905@strong{Description}@* 906Set @var{sec} to the size @var{val}. If the operation is 907ok, then @code{TRUE} is returned, else @code{FALSE}. 908 909Possible error returns: 910@itemize @bullet 911 912@item 913@code{bfd_error_invalid_operation} - 914Writing has started to the BFD, so setting the size is invalid. 915@end itemize 916 917@findex bfd_set_section_contents 918@subsubsection @code{bfd_set_section_contents} 919@strong{Synopsis} 920@example 921bfd_boolean bfd_set_section_contents 922 (bfd *abfd, asection *section, const void *data, 923 file_ptr offset, bfd_size_type count); 924@end example 925@strong{Description}@* 926Sets the contents of the section @var{section} in BFD 927@var{abfd} to the data starting in memory at @var{data}. The 928data is written to the output section starting at offset 929@var{offset} for @var{count} octets. 930 931Normally @code{TRUE} is returned, else @code{FALSE}. Possible error 932returns are: 933@itemize @bullet 934 935@item 936@code{bfd_error_no_contents} - 937The output section does not have the @code{SEC_HAS_CONTENTS} 938attribute, so nothing can be written to it. 939@item 940and some more too 941@end itemize 942This routine is front end to the back end function 943@code{_bfd_set_section_contents}. 944 945@findex bfd_get_section_contents 946@subsubsection @code{bfd_get_section_contents} 947@strong{Synopsis} 948@example 949bfd_boolean bfd_get_section_contents 950 (bfd *abfd, asection *section, void *location, file_ptr offset, 951 bfd_size_type count); 952@end example 953@strong{Description}@* 954Read data from @var{section} in BFD @var{abfd} 955into memory starting at @var{location}. The data is read at an 956offset of @var{offset} from the start of the input section, 957and is read for @var{count} bytes. 958 959If the contents of a constructor with the @code{SEC_CONSTRUCTOR} 960flag set are requested or if the section does not have the 961@code{SEC_HAS_CONTENTS} flag set, then the @var{location} is filled 962with zeroes. If no errors occur, @code{TRUE} is returned, else 963@code{FALSE}. 964 965@findex bfd_malloc_and_get_section 966@subsubsection @code{bfd_malloc_and_get_section} 967@strong{Synopsis} 968@example 969bfd_boolean bfd_malloc_and_get_section 970 (bfd *abfd, asection *section, bfd_byte **buf); 971@end example 972@strong{Description}@* 973Read all data from @var{section} in BFD @var{abfd} 974into a buffer, *@var{buf}, malloc'd by this function. 975 976@findex bfd_copy_private_section_data 977@subsubsection @code{bfd_copy_private_section_data} 978@strong{Synopsis} 979@example 980bfd_boolean bfd_copy_private_section_data 981 (bfd *ibfd, asection *isec, bfd *obfd, asection *osec); 982@end example 983@strong{Description}@* 984Copy private section information from @var{isec} in the BFD 985@var{ibfd} to the section @var{osec} in the BFD @var{obfd}. 986Return @code{TRUE} on success, @code{FALSE} on error. Possible error 987returns are: 988 989@itemize @bullet 990 991@item 992@code{bfd_error_no_memory} - 993Not enough memory exists to create private data for @var{osec}. 994@end itemize 995@example 996#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \ 997 BFD_SEND (obfd, _bfd_copy_private_section_data, \ 998 (ibfd, isection, obfd, osection)) 999@end example 1000 1001@findex bfd_generic_is_group_section 1002@subsubsection @code{bfd_generic_is_group_section} 1003@strong{Synopsis} 1004@example 1005bfd_boolean bfd_generic_is_group_section (bfd *, const asection *sec); 1006@end example 1007@strong{Description}@* 1008Returns TRUE if @var{sec} is a member of a group. 1009 1010@findex bfd_generic_discard_group 1011@subsubsection @code{bfd_generic_discard_group} 1012@strong{Synopsis} 1013@example 1014bfd_boolean bfd_generic_discard_group (bfd *abfd, asection *group); 1015@end example 1016@strong{Description}@* 1017Remove all members of @var{group} from the output. 1018 1019