section.c revision 107492
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. 6 7This file is part of BFD, the Binary File Descriptor library. 8 9This program is free software; you can redistribute it and/or modify 10it under the terms of the GNU General Public License as published by 11the Free Software Foundation; either version 2 of the License, or 12(at your option) any later version. 13 14This program is distributed in the hope that it will be useful, 15but WITHOUT ANY WARRANTY; without even the implied warranty of 16MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17GNU General Public License for more details. 18 19You should have received a copy of the GNU General Public License 20along with this program; if not, write to the Free Software 21Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 22 23/* 24SECTION 25 Sections 26 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. 31 32 Sections are supported in BFD in <<section.c>>. 33 34@menu 35@* Section Input:: 36@* Section Output:: 37@* typedef asection:: 38@* section prototypes:: 39@end menu 40 41INODE 42Section Input, Section Output, Sections, Sections 43SUBSECTION 44 Section input 45 46 When a BFD is opened for reading, the section structures are 47 created and attached to the BFD. 48 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>>. 52 53 Names need not be unique; for example a COFF file may have several 54 sections named <<.data>>. 55 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. 63 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. 73 74INODE 75Section Output, typedef asection, Section Input, Sections 76 77SUBSECTION 78 Section output 79 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>>. 84 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.) 91 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. 99 100 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: 104 105| 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 --------| 114 115SUBSECTION 116 Link orders 117 118 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. 121 122 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. 125 126 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. 133 134*/ 135 136#include "bfd.h" 137#include "sysdep.h" 138#include "libbfd.h" 139#include "bfdlink.h" 140 141/* 142DOCDD 143INODE 144typedef asection, section prototypes, Section Output, Sections 145SUBSECTION 146 typedef asection 147 148 Here is the section structure: 149 150CODE_FRAGMENT 151. 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. *} 156. 157.struct bfd_comdat_info 158.{ 159. {* The name of the symbol associated with a comdat section. *} 160. const char *name; 161. 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; 167.}; 168. 169.typedef struct sec 170.{ 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; 174. 175. {* A unique sequence number. *} 176. int id; 177. 178. {* Which section in the bfd; 0..n-1 as sections are created in a bfd. *} 179. int index; 180. 181. {* The next section in the list belonging to the BFD, or NULL. *} 182. struct sec *next; 183. 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; 188. 189.#define SEC_NO_FLAGS 0x000 190. 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 194. 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 198. 199. {* The section contains data still to be relocated, so there is 200. some relocation information too. *} 201.#define SEC_RELOC 0x004 202. 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 208. 209. {* A signal to the OS that the section contains read only data. *} 210.#define SEC_READONLY 0x010 211. 212. {* The section contains code only. *} 213.#define SEC_CODE 0x020 214. 215. {* The section contains data only. *} 216.#define SEC_DATA 0x040 217. 218. {* The section will reside in ROM. *} 219.#define SEC_ROM 0x080 220. 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 232. 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 237. 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 241. 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 252. 253. {* The section contains thread local data. *} 254.#define SEC_THREAD_LOCAL 0x1000 255. 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 263. 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 270. 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 276. 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 281. 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 286. 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 292. 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 298. 299. {* If SEC_LINK_ONCE is set, this bitfield describes how the linker 300. should handle duplicate sections. *} 301.#define SEC_LINK_DUPLICATES 0x600000 302. 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 306. 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 311. 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 315. 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 320. 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 326. 327. {* This section should not be subject to garbage collection. *} 328.#define SEC_KEEP 0x1000000 329. 330. {* This section contains "short" data, and should be placed 331. "near" the GP. *} 332.#define SEC_SMALL_DATA 0x2000000 333. 334. {* This section contains data which may be shared with other 335. executables or shared objects. *} 336.#define SEC_SHARED 0x4000000 337. 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 343. 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 347. 348. {* Attempt to merge identical entities in the section. 349. Entity size is given in the entsize field. *} 350.#define SEC_MERGE 0x20000000 351. 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 356. 357. {* This section contains data about section groups. *} 358.#define SEC_GROUP 0x80000000 359. 360. {* End of section flags. *} 361. 362. {* Some internal packed boolean fields. *} 363. 364. {* See the vma field. *} 365. unsigned int user_set_vma : 1; 366. 367. {* Whether relocations have been processed. *} 368. unsigned int reloc_done : 1; 369. 370. {* A mark flag used by some of the linker backends. *} 371. unsigned int linker_mark : 1; 372. 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; 376. 377. {* A mark flag used by some linker backends for garbage collection. *} 378. unsigned int gc_mark : 1; 379. 380. {* Used by the ELF code to mark sections which have been allocated 381. to segments. *} 382. unsigned int segment_mark : 1; 383. 384. {* End of internal packed boolean fields. *} 385. 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; 393. 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; 398. 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; 403. 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; 408. 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; 417. 418. {* The output section through which to map on output. *} 419. struct sec *output_section; 420. 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; 424. 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; 428. 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; 432. 433. {* The number of relocation records in one of the above. *} 434. unsigned reloc_count; 435. 436. {* Information below is back end specific - and not always used 437. or updated. *} 438. 439. {* File position of section data. *} 440. file_ptr filepos; 441. 442. {* File position of relocation info. *} 443. file_ptr rel_filepos; 444. 445. {* File position of line data. *} 446. file_ptr line_filepos; 447. 448. {* Pointer to data for applications. *} 449. PTR userdata; 450. 451. {* If the SEC_IN_MEMORY flag is set, this points to the actual 452. contents. *} 453. unsigned char *contents; 454. 455. {* Attached line number information. *} 456. alent *lineno; 457. 458. {* Number of line number records. *} 459. unsigned int lineno_count; 460. 461. {* Entity size for merging purposes. *} 462. unsigned int entsize; 463. 464. {* Optional information about a COMDAT entry; NULL if not COMDAT. *} 465. struct bfd_comdat_info *comdat; 466. 467. {* When a section is being output, this value changes as more 468. linenumbers are written out. *} 469. file_ptr moving_line_filepos; 470. 471. {* What the section number is in the target world. *} 472. int target_index; 473. 474. PTR used_by_bfd; 475. 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; 479. 480. {* The BFD which owns the section. *} 481. bfd *owner; 482. 483. {* A symbol which points at this section only. *} 484. struct symbol_cache_entry *symbol; 485. struct symbol_cache_entry **symbol_ptr_ptr; 486. 487. struct bfd_link_order *link_order_head; 488. struct bfd_link_order *link_order_tail; 489.} asection; 490. 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*" 500. 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) 516. 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)) 522. 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)) 533. 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) 558. 559*/ 560 561/* 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 572 573/* These symbols are global, not specific to any BFD. Therefore, anything 574 that tries to change them is broken, and should be repaired. */ 575 576static const asymbol global_syms[] = 577{ 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) 582}; 583 584#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, \ 589 \ 590 /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \ 591 0, 0, 1, 0, \ 592 \ 593 /* vma, lma, _cooked_size, _raw_size, */ \ 594 0, 0, 0, 0, \ 595 \ 596 /* output_offset, output_section, alignment_power, */ \ 597 0, (struct sec *) &SEC, 0, \ 598 \ 599 /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \ 600 NULL, NULL, 0, 0, 0, \ 601 \ 602 /* line_filepos, userdata, contents, lineno, lineno_count, */ \ 603 0, NULL, NULL, NULL, 0, \ 604 \ 605 /* entsize, comdat, moving_line_filepos, */ \ 606 0, NULL, 0, \ 607 \ 608 /* target_index, used_by_bfd, constructor_chain, owner, */ \ 609 0, NULL, NULL, NULL, \ 610 \ 611 /* symbol, */ \ 612 (struct symbol_cache_entry *) &global_syms[IDX], \ 613 \ 614 /* symbol_ptr_ptr, */ \ 615 (struct symbol_cache_entry **) &SYM, \ 616 \ 617 /* link_order_head, link_order_tail */ \ 618 NULL, NULL \ 619 } 620 621STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol, 622 BFD_COM_SECTION_NAME, 0); 623STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1); 624STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2); 625STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3); 626#undef STD_SECTION 627 628struct section_hash_entry 629{ 630 struct bfd_hash_entry root; 631 asection section; 632}; 633 634/* Initialize an entry in the section hash table. */ 635 636struct bfd_hash_entry * 637bfd_section_hash_newfunc (entry, table, string) 638 struct bfd_hash_entry *entry; 639 struct bfd_hash_table *table; 640 const char *string; 641{ 642 /* Allocate the structure if it has not already been allocated by a 643 subclass. */ 644 if (entry == NULL) 645 { 646 entry = (struct bfd_hash_entry *) 647 bfd_hash_allocate (table, sizeof (struct section_hash_entry)); 648 if (entry == NULL) 649 return entry; 650 } 651 652 /* Call the allocation method of the superclass. */ 653 entry = bfd_hash_newfunc (entry, table, string); 654 if (entry != NULL) 655 { 656 memset ((PTR) &((struct section_hash_entry *) entry)->section, 657 0, sizeof (asection)); 658 } 659 660 return entry; 661} 662 663#define section_hash_lookup(table, string, create, copy) \ 664 ((struct section_hash_entry *) \ 665 bfd_hash_lookup ((table), (string), (create), (copy))) 666 667/* Initializes a new section. NEWSECT->NAME is already set. */ 668 669static asection *bfd_section_init PARAMS ((bfd *, asection *)); 670 671static asection * 672bfd_section_init (abfd, newsect) 673 bfd *abfd; 674 asection *newsect; 675{ 676 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */ 677 678 newsect->id = section_id; 679 newsect->index = abfd->section_count; 680 newsect->owner = abfd; 681 682 /* 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; 688 689 newsect->symbol->name = newsect->name; 690 newsect->symbol->value = 0; 691 newsect->symbol->section = newsect; 692 newsect->symbol->flags = BSF_SECTION_SYM; 693 694 newsect->symbol_ptr_ptr = &newsect->symbol; 695 696 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect))) 697 return NULL; 698 699 section_id++; 700 abfd->section_count++; 701 *abfd->section_tail = newsect; 702 abfd->section_tail = &newsect->next; 703 return newsect; 704} 705 706/* 707DOCDD 708INODE 709section prototypes, , typedef asection, Sections 710SUBSECTION 711 Section prototypes 712 713These are the functions exported by the section handling part of BFD. 714*/ 715 716/* 717FUNCTION 718 bfd_section_list_clear 719 720SYNOPSIS 721 void bfd_section_list_clear (bfd *); 722 723DESCRIPTION 724 Clears the section list, and also resets the section count and 725 hash table entries. 726*/ 727 728void 729bfd_section_list_clear (abfd) 730 bfd *abfd; 731{ 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 *)); 737} 738 739/* 740FUNCTION 741 bfd_get_section_by_name 742 743SYNOPSIS 744 asection *bfd_get_section_by_name(bfd *abfd, const char *name); 745 746DESCRIPTION 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. 750 751 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. 755*/ 756 757asection * 758bfd_get_section_by_name (abfd, name) 759 bfd *abfd; 760 const char *name; 761{ 762 struct section_hash_entry *sh; 763 764 sh = section_hash_lookup (&abfd->section_htab, name, false, false); 765 if (sh != NULL) 766 return &sh->section; 767 768 return NULL; 769} 770 771/* 772FUNCTION 773 bfd_get_unique_section_name 774 775SYNOPSIS 776 char *bfd_get_unique_section_name(bfd *abfd, 777 const char *templat, 778 int *count); 779 780DESCRIPTION 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. 786*/ 787 788char * 789bfd_get_unique_section_name (abfd, templat, count) 790 bfd *abfd; 791 const char *templat; 792 int *count; 793{ 794 int num; 795 unsigned int len; 796 char *sname; 797 798 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; 806 807 do 808 { 809 /* If we have a million sections, something is badly wrong. */ 810 if (num > 999999) 811 abort (); 812 sprintf (sname + len, ".%d", num++); 813 } 814 while (section_hash_lookup (&abfd->section_htab, sname, false, false)); 815 816 if (count != NULL) 817 *count = num; 818 return sname; 819} 820 821/* 822FUNCTION 823 bfd_make_section_old_way 824 825SYNOPSIS 826 asection *bfd_make_section_old_way(bfd *abfd, const char *name); 827 828DESCRIPTION 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. 834 835 It has the funny name since this is the way it used to be 836 before it was rewritten.... 837 838 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. 843 844*/ 845 846asection * 847bfd_make_section_old_way (abfd, name) 848 bfd *abfd; 849 const char *name; 850{ 851 struct section_hash_entry *sh; 852 asection *newsect; 853 854 if (abfd->output_has_begun) 855 { 856 bfd_set_error (bfd_error_invalid_operation); 857 return NULL; 858 } 859 860 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0) 861 return bfd_abs_section_ptr; 862 863 if (strcmp (name, BFD_COM_SECTION_NAME) == 0) 864 return bfd_com_section_ptr; 865 866 if (strcmp (name, BFD_UND_SECTION_NAME) == 0) 867 return bfd_und_section_ptr; 868 869 if (strcmp (name, BFD_IND_SECTION_NAME) == 0) 870 return bfd_ind_section_ptr; 871 872 sh = section_hash_lookup (&abfd->section_htab, name, true, false); 873 if (sh == NULL) 874 return NULL; 875 876 newsect = &sh->section; 877 if (newsect->name != NULL) 878 { 879 /* Section already exists. */ 880 return newsect; 881 } 882 883 newsect->name = name; 884 return bfd_section_init (abfd, newsect); 885} 886 887/* 888FUNCTION 889 bfd_make_section_anyway 890 891SYNOPSIS 892 asection *bfd_make_section_anyway(bfd *abfd, const char *name); 893 894DESCRIPTION 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. 898 899 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. 902*/ 903 904sec_ptr 905bfd_make_section_anyway (abfd, name) 906 bfd *abfd; 907 const char *name; 908{ 909 struct section_hash_entry *sh; 910 asection *newsect; 911 912 if (abfd->output_has_begun) 913 { 914 bfd_set_error (bfd_error_invalid_operation); 915 return NULL; 916 } 917 918 sh = section_hash_lookup (&abfd->section_htab, name, true, false); 919 if (sh == NULL) 920 return NULL; 921 922 newsect = &sh->section; 923 if (newsect->name != NULL) 924 { 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; 932 } 933 934 newsect->name = name; 935 return bfd_section_init (abfd, newsect); 936} 937 938/* 939FUNCTION 940 bfd_make_section 941 942SYNOPSIS 943 asection *bfd_make_section(bfd *, const char *name); 944 945DESCRIPTION 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>>. 950*/ 951 952asection * 953bfd_make_section (abfd, name) 954 bfd *abfd; 955 const char *name; 956{ 957 struct section_hash_entry *sh; 958 asection *newsect; 959 960 if (abfd->output_has_begun) 961 { 962 bfd_set_error (bfd_error_invalid_operation); 963 return NULL; 964 } 965 966 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; 971 972 sh = section_hash_lookup (&abfd->section_htab, name, true, false); 973 if (sh == NULL) 974 return NULL; 975 976 newsect = &sh->section; 977 if (newsect->name != NULL) 978 { 979 /* Section already exists. */ 980 return newsect; 981 } 982 983 newsect->name = name; 984 return bfd_section_init (abfd, newsect); 985} 986 987/* 988FUNCTION 989 bfd_set_section_flags 990 991SYNOPSIS 992 boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags); 993 994DESCRIPTION 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: 998 999 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. 1003 1004*/ 1005 1006/*ARGSUSED*/ 1007boolean 1008bfd_set_section_flags (abfd, section, flags) 1009 bfd *abfd ATTRIBUTE_UNUSED; 1010 sec_ptr section; 1011 flagword flags; 1012{ 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 */ 1018 1019 if ((flags & bfd_applicable_section_flags (abfd)) != flags) 1020 { 1021 bfd_set_error (bfd_error_invalid_operation); 1022 return false; 1023 } 1024#endif 1025 1026 section->flags = flags; 1027 return true; 1028} 1029 1030/* 1031FUNCTION 1032 bfd_map_over_sections 1033 1034SYNOPSIS 1035 void bfd_map_over_sections(bfd *abfd, 1036 void (*func) (bfd *abfd, 1037 asection *sect, 1038 PTR obj), 1039 PTR obj); 1040 1041DESCRIPTION 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 1045 1046| func(abfd, the_section, obj); 1047 1048 This is the prefered method for iterating over sections; an 1049 alternative would be to use a loop: 1050 1051| section *p; 1052| for (p = abfd->sections; p != NULL; p = p->next) 1053| func(abfd, p, ...) 1054 1055*/ 1056 1057/*VARARGS2*/ 1058void 1059bfd_map_over_sections (abfd, operation, user_storage) 1060 bfd *abfd; 1061 void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj)); 1062 PTR user_storage; 1063{ 1064 asection *sect; 1065 unsigned int i = 0; 1066 1067 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next) 1068 (*operation) (abfd, sect, user_storage); 1069 1070 if (i != abfd->section_count) /* Debugging */ 1071 abort (); 1072} 1073 1074/* 1075FUNCTION 1076 bfd_set_section_size 1077 1078SYNOPSIS 1079 boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val); 1080 1081DESCRIPTION 1082 Set @var{sec} to the size @var{val}. If the operation is 1083 ok, then <<true>> is returned, else <<false>>. 1084 1085 Possible error returns: 1086 o <<bfd_error_invalid_operation>> - 1087 Writing has started to the BFD, so setting the size is invalid. 1088 1089*/ 1090 1091boolean 1092bfd_set_section_size (abfd, ptr, val) 1093 bfd *abfd; 1094 sec_ptr ptr; 1095 bfd_size_type val; 1096{ 1097 /* Once you've started writing to any section you cannot create or change 1098 the size of any others. */ 1099 1100 if (abfd->output_has_begun) 1101 { 1102 bfd_set_error (bfd_error_invalid_operation); 1103 return false; 1104 } 1105 1106 ptr->_cooked_size = val; 1107 ptr->_raw_size = val; 1108 1109 return true; 1110} 1111 1112/* 1113FUNCTION 1114 bfd_set_section_contents 1115 1116SYNOPSIS 1117 boolean bfd_set_section_contents (bfd *abfd, asection *section, 1118 PTR data, file_ptr offset, 1119 bfd_size_type count); 1120 1121DESCRIPTION 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. 1126 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 1133 1134 This routine is front end to the back end function 1135 <<_bfd_set_section_contents>>. 1136 1137*/ 1138 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)) 1143 1144boolean 1145bfd_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; 1151{ 1152 bfd_size_type sz; 1153 1154 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS)) 1155 { 1156 bfd_set_error (bfd_error_no_contents); 1157 return (false); 1158 } 1159 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) 1165 { 1166 bfd_set_error (bfd_error_bad_value); 1167 return false; 1168 } 1169 1170 switch (abfd->direction) 1171 { 1172 case read_direction: 1173 case no_direction: 1174 bfd_set_error (bfd_error_invalid_operation); 1175 return false; 1176 1177 case write_direction: 1178 break; 1179 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; 1186 } 1187 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); 1192 1193 if (BFD_SEND (abfd, _bfd_set_section_contents, 1194 (abfd, section, location, offset, count))) 1195 { 1196 abfd->output_has_begun = true; 1197 return true; 1198 } 1199 1200 return false; 1201} 1202 1203/* 1204FUNCTION 1205 bfd_get_section_contents 1206 1207SYNOPSIS 1208 boolean bfd_get_section_contents (bfd *abfd, asection *section, 1209 PTR location, file_ptr offset, 1210 bfd_size_type count); 1211 1212DESCRIPTION 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. 1217 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>>. 1223 1224*/ 1225boolean 1226bfd_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; 1232{ 1233 bfd_size_type sz; 1234 1235 if (section->flags & SEC_CONSTRUCTOR) 1236 { 1237 memset (location, 0, (size_t) count); 1238 return true; 1239 } 1240 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) 1248 { 1249 bfd_set_error (bfd_error_bad_value); 1250 return false; 1251 } 1252 1253 if (count == 0) 1254 /* Don't bother. */ 1255 return true; 1256 1257 if ((section->flags & SEC_HAS_CONTENTS) == 0) 1258 { 1259 memset (location, 0, (size_t) count); 1260 return true; 1261 } 1262 1263 if ((section->flags & SEC_IN_MEMORY) != 0) 1264 { 1265 memcpy (location, section->contents + offset, (size_t) count); 1266 return true; 1267 } 1268 1269 return BFD_SEND (abfd, _bfd_get_section_contents, 1270 (abfd, section, location, offset, count)); 1271} 1272 1273/* 1274FUNCTION 1275 bfd_copy_private_section_data 1276 1277SYNOPSIS 1278 boolean bfd_copy_private_section_data (bfd *ibfd, asection *isec, 1279 bfd *obfd, asection *osec); 1280 1281DESCRIPTION 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: 1286 1287 o <<bfd_error_no_memory>> - 1288 Not enough memory exists to create private data for @var{osec}. 1289 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)) 1293*/ 1294 1295/* 1296FUNCTION 1297 _bfd_strip_section_from_output 1298 1299SYNOPSIS 1300 void _bfd_strip_section_from_output 1301 (struct bfd_link_info *info, asection *section); 1302 1303DESCRIPTION 1304 Remove @var{section} from the output. If the output section 1305 becomes empty, remove it from the output bfd. 1306 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. 1310*/ 1311void 1312_bfd_strip_section_from_output (info, s) 1313 struct bfd_link_info *info; 1314 asection *s; 1315{ 1316 asection *os; 1317 asection *is; 1318 bfd *abfd; 1319 1320 s->flags |= SEC_EXCLUDE; 1321 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; 1328 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; 1335 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; 1339} 1340 1341/* 1342FUNCTION 1343 bfd_generic_discard_group 1344 1345SYNOPSIS 1346 boolean bfd_generic_discard_group (bfd *abfd, asection *group); 1347 1348DESCRIPTION 1349 Remove all members of @var{group} from the output. 1350*/ 1351 1352boolean 1353bfd_generic_discard_group (abfd, group) 1354 bfd *abfd ATTRIBUTE_UNUSED; 1355 asection *group ATTRIBUTE_UNUSED; 1356{ 1357 return true; 1358} 1359