section.c revision 104834
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 = bfd_hash_allocate (table, sizeof (struct section_hash_entry)); 647 if (entry == NULL) 648 return entry; 649 } 650 651 /* Call the allocation method of the superclass. */ 652 entry = bfd_hash_newfunc (entry, table, string); 653 if (entry != NULL) 654 { 655 memset ((PTR) &((struct section_hash_entry *) entry)->section, 656 0, sizeof (asection)); 657 } 658 659 return entry; 660} 661 662#define section_hash_lookup(table, string, create, copy) \ 663 ((struct section_hash_entry *) \ 664 bfd_hash_lookup ((table), (string), (create), (copy))) 665 666/* Initializes a new section. NEWSECT->NAME is already set. */ 667 668static asection *bfd_section_init PARAMS ((bfd *, asection *)); 669 670static asection * 671bfd_section_init (abfd, newsect) 672 bfd *abfd; 673 asection *newsect; 674{ 675 static int section_id = 0x10; /* id 0 to 3 used by STD_SECTION. */ 676 677 newsect->id = section_id; 678 newsect->index = abfd->section_count; 679 newsect->owner = abfd; 680 681 /* Create a symbol whose only job is to point to this section. This 682 is useful for things like relocs which are relative to the base 683 of a section. */ 684 newsect->symbol = bfd_make_empty_symbol (abfd); 685 if (newsect->symbol == NULL) 686 return NULL; 687 688 newsect->symbol->name = newsect->name; 689 newsect->symbol->value = 0; 690 newsect->symbol->section = newsect; 691 newsect->symbol->flags = BSF_SECTION_SYM; 692 693 newsect->symbol_ptr_ptr = &newsect->symbol; 694 695 if (! BFD_SEND (abfd, _new_section_hook, (abfd, newsect))) 696 return NULL; 697 698 section_id++; 699 abfd->section_count++; 700 *abfd->section_tail = newsect; 701 abfd->section_tail = &newsect->next; 702 return newsect; 703} 704 705/* 706DOCDD 707INODE 708section prototypes, , typedef asection, Sections 709SUBSECTION 710 Section prototypes 711 712These are the functions exported by the section handling part of BFD. 713*/ 714 715/* 716FUNCTION 717 bfd_section_list_clear 718 719SYNOPSIS 720 void bfd_section_list_clear (bfd *); 721 722DESCRIPTION 723 Clears the section list, and also resets the section count and 724 hash table entries. 725*/ 726 727void 728bfd_section_list_clear (abfd) 729 bfd *abfd; 730{ 731 abfd->sections = NULL; 732 abfd->section_tail = &abfd->sections; 733 abfd->section_count = 0; 734 memset ((PTR) abfd->section_htab.table, 0, 735 abfd->section_htab.size * sizeof (struct bfd_hash_entry *)); 736} 737 738/* 739FUNCTION 740 bfd_get_section_by_name 741 742SYNOPSIS 743 asection *bfd_get_section_by_name(bfd *abfd, const char *name); 744 745DESCRIPTION 746 Run through @var{abfd} and return the one of the 747 <<asection>>s whose name matches @var{name}, otherwise <<NULL>>. 748 @xref{Sections}, for more information. 749 750 This should only be used in special cases; the normal way to process 751 all sections of a given name is to use <<bfd_map_over_sections>> and 752 <<strcmp>> on the name (or better yet, base it on the section flags 753 or something else) for each section. 754*/ 755 756asection * 757bfd_get_section_by_name (abfd, name) 758 bfd *abfd; 759 const char *name; 760{ 761 struct section_hash_entry *sh; 762 763 sh = section_hash_lookup (&abfd->section_htab, name, false, false); 764 if (sh != NULL) 765 return &sh->section; 766 767 return NULL; 768} 769 770/* 771FUNCTION 772 bfd_get_unique_section_name 773 774SYNOPSIS 775 char *bfd_get_unique_section_name(bfd *abfd, 776 const char *templat, 777 int *count); 778 779DESCRIPTION 780 Invent a section name that is unique in @var{abfd} by tacking 781 a dot and a digit suffix onto the original @var{templat}. If 782 @var{count} is non-NULL, then it specifies the first number 783 tried as a suffix to generate a unique name. The value 784 pointed to by @var{count} will be incremented in this case. 785*/ 786 787char * 788bfd_get_unique_section_name (abfd, templat, count) 789 bfd *abfd; 790 const char *templat; 791 int *count; 792{ 793 int num; 794 unsigned int len; 795 char *sname; 796 797 len = strlen (templat); 798 sname = bfd_malloc ((bfd_size_type) len + 8); 799 if (sname == NULL) 800 return NULL; 801 memcpy (sname, templat, len); 802 num = 1; 803 if (count != NULL) 804 num = *count; 805 806 do 807 { 808 /* If we have a million sections, something is badly wrong. */ 809 if (num > 999999) 810 abort (); 811 sprintf (sname + len, ".%d", num++); 812 } 813 while (section_hash_lookup (&abfd->section_htab, sname, false, false)); 814 815 if (count != NULL) 816 *count = num; 817 return sname; 818} 819 820/* 821FUNCTION 822 bfd_make_section_old_way 823 824SYNOPSIS 825 asection *bfd_make_section_old_way(bfd *abfd, const char *name); 826 827DESCRIPTION 828 Create a new empty section called @var{name} 829 and attach it to the end of the chain of sections for the 830 BFD @var{abfd}. An attempt to create a section with a name which 831 is already in use returns its pointer without changing the 832 section chain. 833 834 It has the funny name since this is the way it used to be 835 before it was rewritten.... 836 837 Possible errors are: 838 o <<bfd_error_invalid_operation>> - 839 If output has already started for this BFD. 840 o <<bfd_error_no_memory>> - 841 If memory allocation fails. 842 843*/ 844 845asection * 846bfd_make_section_old_way (abfd, name) 847 bfd *abfd; 848 const char *name; 849{ 850 struct section_hash_entry *sh; 851 asection *newsect; 852 853 if (abfd->output_has_begun) 854 { 855 bfd_set_error (bfd_error_invalid_operation); 856 return NULL; 857 } 858 859 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0) 860 return bfd_abs_section_ptr; 861 862 if (strcmp (name, BFD_COM_SECTION_NAME) == 0) 863 return bfd_com_section_ptr; 864 865 if (strcmp (name, BFD_UND_SECTION_NAME) == 0) 866 return bfd_und_section_ptr; 867 868 if (strcmp (name, BFD_IND_SECTION_NAME) == 0) 869 return bfd_ind_section_ptr; 870 871 sh = section_hash_lookup (&abfd->section_htab, name, true, false); 872 if (sh == NULL) 873 return NULL; 874 875 newsect = &sh->section; 876 if (newsect->name != NULL) 877 { 878 /* Section already exists. */ 879 return newsect; 880 } 881 882 newsect->name = name; 883 return bfd_section_init (abfd, newsect); 884} 885 886/* 887FUNCTION 888 bfd_make_section_anyway 889 890SYNOPSIS 891 asection *bfd_make_section_anyway(bfd *abfd, const char *name); 892 893DESCRIPTION 894 Create a new empty section called @var{name} and attach it to the end of 895 the chain of sections for @var{abfd}. Create a new section even if there 896 is already a section with that name. 897 898 Return <<NULL>> and set <<bfd_error>> on error; possible errors are: 899 o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}. 900 o <<bfd_error_no_memory>> - If memory allocation fails. 901*/ 902 903sec_ptr 904bfd_make_section_anyway (abfd, name) 905 bfd *abfd; 906 const char *name; 907{ 908 struct section_hash_entry *sh; 909 asection *newsect; 910 911 if (abfd->output_has_begun) 912 { 913 bfd_set_error (bfd_error_invalid_operation); 914 return NULL; 915 } 916 917 sh = section_hash_lookup (&abfd->section_htab, name, true, false); 918 if (sh == NULL) 919 return NULL; 920 921 newsect = &sh->section; 922 if (newsect->name != NULL) 923 { 924 /* We are making a section of the same name. It can't go in 925 section_htab without generating a unique section name and 926 that would be pointless; We don't need to traverse the 927 hash table. */ 928 newsect = (asection *) bfd_zalloc (abfd, sizeof (asection)); 929 if (newsect == NULL) 930 return NULL; 931 } 932 933 newsect->name = name; 934 return bfd_section_init (abfd, newsect); 935} 936 937/* 938FUNCTION 939 bfd_make_section 940 941SYNOPSIS 942 asection *bfd_make_section(bfd *, const char *name); 943 944DESCRIPTION 945 Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling 946 bfd_set_error ()) without changing the section chain if there is already a 947 section named @var{name}. If there is an error, return <<NULL>> and set 948 <<bfd_error>>. 949*/ 950 951asection * 952bfd_make_section (abfd, name) 953 bfd *abfd; 954 const char *name; 955{ 956 struct section_hash_entry *sh; 957 asection *newsect; 958 959 if (abfd->output_has_begun) 960 { 961 bfd_set_error (bfd_error_invalid_operation); 962 return NULL; 963 } 964 965 if (strcmp (name, BFD_ABS_SECTION_NAME) == 0 966 || strcmp (name, BFD_COM_SECTION_NAME) == 0 967 || strcmp (name, BFD_UND_SECTION_NAME) == 0 968 || strcmp (name, BFD_IND_SECTION_NAME) == 0) 969 return NULL; 970 971 sh = section_hash_lookup (&abfd->section_htab, name, true, false); 972 if (sh == NULL) 973 return NULL; 974 975 newsect = &sh->section; 976 if (newsect->name != NULL) 977 { 978 /* Section already exists. */ 979 return newsect; 980 } 981 982 newsect->name = name; 983 return bfd_section_init (abfd, newsect); 984} 985 986/* 987FUNCTION 988 bfd_set_section_flags 989 990SYNOPSIS 991 boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags); 992 993DESCRIPTION 994 Set the attributes of the section @var{sec} in the BFD 995 @var{abfd} to the value @var{flags}. Return <<true>> on success, 996 <<false>> on error. Possible error returns are: 997 998 o <<bfd_error_invalid_operation>> - 999 The section cannot have one or more of the attributes 1000 requested. For example, a .bss section in <<a.out>> may not 1001 have the <<SEC_HAS_CONTENTS>> field set. 1002 1003*/ 1004 1005/*ARGSUSED*/ 1006boolean 1007bfd_set_section_flags (abfd, section, flags) 1008 bfd *abfd ATTRIBUTE_UNUSED; 1009 sec_ptr section; 1010 flagword flags; 1011{ 1012#if 0 1013 /* If you try to copy a text section from an input file (where it 1014 has the SEC_CODE flag set) to an output file, this loses big if 1015 the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE 1016 set - which it doesn't, at least not for a.out. FIXME */ 1017 1018 if ((flags & bfd_applicable_section_flags (abfd)) != flags) 1019 { 1020 bfd_set_error (bfd_error_invalid_operation); 1021 return false; 1022 } 1023#endif 1024 1025 section->flags = flags; 1026 return true; 1027} 1028 1029/* 1030FUNCTION 1031 bfd_map_over_sections 1032 1033SYNOPSIS 1034 void bfd_map_over_sections(bfd *abfd, 1035 void (*func) (bfd *abfd, 1036 asection *sect, 1037 PTR obj), 1038 PTR obj); 1039 1040DESCRIPTION 1041 Call the provided function @var{func} for each section 1042 attached to the BFD @var{abfd}, passing @var{obj} as an 1043 argument. The function will be called as if by 1044 1045| func(abfd, the_section, obj); 1046 1047 This is the prefered method for iterating over sections; an 1048 alternative would be to use a loop: 1049 1050| section *p; 1051| for (p = abfd->sections; p != NULL; p = p->next) 1052| func(abfd, p, ...) 1053 1054*/ 1055 1056/*VARARGS2*/ 1057void 1058bfd_map_over_sections (abfd, operation, user_storage) 1059 bfd *abfd; 1060 void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj)); 1061 PTR user_storage; 1062{ 1063 asection *sect; 1064 unsigned int i = 0; 1065 1066 for (sect = abfd->sections; sect != NULL; i++, sect = sect->next) 1067 (*operation) (abfd, sect, user_storage); 1068 1069 if (i != abfd->section_count) /* Debugging */ 1070 abort (); 1071} 1072 1073/* 1074FUNCTION 1075 bfd_set_section_size 1076 1077SYNOPSIS 1078 boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val); 1079 1080DESCRIPTION 1081 Set @var{sec} to the size @var{val}. If the operation is 1082 ok, then <<true>> is returned, else <<false>>. 1083 1084 Possible error returns: 1085 o <<bfd_error_invalid_operation>> - 1086 Writing has started to the BFD, so setting the size is invalid. 1087 1088*/ 1089 1090boolean 1091bfd_set_section_size (abfd, ptr, val) 1092 bfd *abfd; 1093 sec_ptr ptr; 1094 bfd_size_type val; 1095{ 1096 /* Once you've started writing to any section you cannot create or change 1097 the size of any others. */ 1098 1099 if (abfd->output_has_begun) 1100 { 1101 bfd_set_error (bfd_error_invalid_operation); 1102 return false; 1103 } 1104 1105 ptr->_cooked_size = val; 1106 ptr->_raw_size = val; 1107 1108 return true; 1109} 1110 1111/* 1112FUNCTION 1113 bfd_set_section_contents 1114 1115SYNOPSIS 1116 boolean bfd_set_section_contents (bfd *abfd, asection *section, 1117 PTR data, file_ptr offset, 1118 bfd_size_type count); 1119 1120DESCRIPTION 1121 Sets the contents of the section @var{section} in BFD 1122 @var{abfd} to the data starting in memory at @var{data}. The 1123 data is written to the output section starting at offset 1124 @var{offset} for @var{count} octets. 1125 1126 Normally <<true>> is returned, else <<false>>. Possible error 1127 returns are: 1128 o <<bfd_error_no_contents>> - 1129 The output section does not have the <<SEC_HAS_CONTENTS>> 1130 attribute, so nothing can be written to it. 1131 o and some more too 1132 1133 This routine is front end to the back end function 1134 <<_bfd_set_section_contents>>. 1135 1136*/ 1137 1138#define bfd_get_section_size_now(abfd,sec) \ 1139(sec->reloc_done \ 1140 ? bfd_get_section_size_after_reloc (sec) \ 1141 : bfd_get_section_size_before_reloc (sec)) 1142 1143boolean 1144bfd_set_section_contents (abfd, section, location, offset, count) 1145 bfd *abfd; 1146 sec_ptr section; 1147 PTR location; 1148 file_ptr offset; 1149 bfd_size_type count; 1150{ 1151 bfd_size_type sz; 1152 1153 if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS)) 1154 { 1155 bfd_set_error (bfd_error_no_contents); 1156 return (false); 1157 } 1158 1159 sz = bfd_get_section_size_now (abfd, section); 1160 if ((bfd_size_type) offset > sz 1161 || count > sz 1162 || offset + count > sz 1163 || count != (size_t) count) 1164 { 1165 bfd_set_error (bfd_error_bad_value); 1166 return false; 1167 } 1168 1169 switch (abfd->direction) 1170 { 1171 case read_direction: 1172 case no_direction: 1173 bfd_set_error (bfd_error_invalid_operation); 1174 return false; 1175 1176 case write_direction: 1177 break; 1178 1179 case both_direction: 1180 /* File is opened for update. `output_has_begun' some time ago when 1181 the file was created. Do not recompute sections sizes or alignments 1182 in _bfd_set_section_content. */ 1183 abfd->output_has_begun = true; 1184 break; 1185 } 1186 1187 /* Record a copy of the data in memory if desired. */ 1188 if (section->contents 1189 && location != section->contents + offset) 1190 memcpy (section->contents + offset, location, (size_t) count); 1191 1192 if (BFD_SEND (abfd, _bfd_set_section_contents, 1193 (abfd, section, location, offset, count))) 1194 { 1195 abfd->output_has_begun = true; 1196 return true; 1197 } 1198 1199 return false; 1200} 1201 1202/* 1203FUNCTION 1204 bfd_get_section_contents 1205 1206SYNOPSIS 1207 boolean bfd_get_section_contents (bfd *abfd, asection *section, 1208 PTR location, file_ptr offset, 1209 bfd_size_type count); 1210 1211DESCRIPTION 1212 Read data from @var{section} in BFD @var{abfd} 1213 into memory starting at @var{location}. The data is read at an 1214 offset of @var{offset} from the start of the input section, 1215 and is read for @var{count} bytes. 1216 1217 If the contents of a constructor with the <<SEC_CONSTRUCTOR>> 1218 flag set are requested or if the section does not have the 1219 <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled 1220 with zeroes. If no errors occur, <<true>> is returned, else 1221 <<false>>. 1222 1223*/ 1224boolean 1225bfd_get_section_contents (abfd, section, location, offset, count) 1226 bfd *abfd; 1227 sec_ptr section; 1228 PTR location; 1229 file_ptr offset; 1230 bfd_size_type count; 1231{ 1232 bfd_size_type sz; 1233 1234 if (section->flags & SEC_CONSTRUCTOR) 1235 { 1236 memset (location, 0, (size_t) count); 1237 return true; 1238 } 1239 1240 /* Even if reloc_done is true, this function reads unrelocated 1241 contents, so we want the raw size. */ 1242 sz = section->_raw_size; 1243 if ((bfd_size_type) offset > sz 1244 || count > sz 1245 || offset + count > sz 1246 || count != (size_t) count) 1247 { 1248 bfd_set_error (bfd_error_bad_value); 1249 return false; 1250 } 1251 1252 if (count == 0) 1253 /* Don't bother. */ 1254 return true; 1255 1256 if ((section->flags & SEC_HAS_CONTENTS) == 0) 1257 { 1258 memset (location, 0, (size_t) count); 1259 return true; 1260 } 1261 1262 if ((section->flags & SEC_IN_MEMORY) != 0) 1263 { 1264 memcpy (location, section->contents + offset, (size_t) count); 1265 return true; 1266 } 1267 1268 return BFD_SEND (abfd, _bfd_get_section_contents, 1269 (abfd, section, location, offset, count)); 1270} 1271 1272/* 1273FUNCTION 1274 bfd_copy_private_section_data 1275 1276SYNOPSIS 1277 boolean bfd_copy_private_section_data (bfd *ibfd, asection *isec, 1278 bfd *obfd, asection *osec); 1279 1280DESCRIPTION 1281 Copy private section information from @var{isec} in the BFD 1282 @var{ibfd} to the section @var{osec} in the BFD @var{obfd}. 1283 Return <<true>> on success, <<false>> on error. Possible error 1284 returns are: 1285 1286 o <<bfd_error_no_memory>> - 1287 Not enough memory exists to create private data for @var{osec}. 1288 1289.#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \ 1290. BFD_SEND (obfd, _bfd_copy_private_section_data, \ 1291. (ibfd, isection, obfd, osection)) 1292*/ 1293 1294/* 1295FUNCTION 1296 _bfd_strip_section_from_output 1297 1298SYNOPSIS 1299 void _bfd_strip_section_from_output 1300 (struct bfd_link_info *info, asection *section); 1301 1302DESCRIPTION 1303 Remove @var{section} from the output. If the output section 1304 becomes empty, remove it from the output bfd. 1305 1306 This function won't actually do anything except twiddle flags 1307 if called too late in the linking process, when it's not safe 1308 to remove sections. 1309*/ 1310void 1311_bfd_strip_section_from_output (info, s) 1312 struct bfd_link_info *info; 1313 asection *s; 1314{ 1315 asection *os; 1316 asection *is; 1317 bfd *abfd; 1318 1319 s->flags |= SEC_EXCLUDE; 1320 1321 /* If the section wasn't assigned to an output section, or the 1322 section has been discarded by the linker script, there's nothing 1323 more to do. */ 1324 os = s->output_section; 1325 if (os == NULL || os->owner == NULL) 1326 return; 1327 1328 /* If the output section has other (non-excluded) input sections, we 1329 can't remove it. */ 1330 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next) 1331 for (is = abfd->sections; is != NULL; is = is->next) 1332 if (is->output_section == os && (is->flags & SEC_EXCLUDE) == 0) 1333 return; 1334 1335 /* If the output section is empty, flag it for removal too. 1336 See ldlang.c:strip_excluded_output_sections for the action. */ 1337 os->flags |= SEC_EXCLUDE; 1338} 1339 1340/* 1341FUNCTION 1342 bfd_generic_discard_group 1343 1344SYNOPSIS 1345 boolean bfd_generic_discard_group (bfd *abfd, asection *group); 1346 1347DESCRIPTION 1348 Remove all members of @var{group} from the output. 1349*/ 1350 1351boolean 1352bfd_generic_discard_group (abfd, group) 1353 bfd *abfd ATTRIBUTE_UNUSED; 1354 asection *group ATTRIBUTE_UNUSED; 1355{ 1356 return true; 1357} 1358