bfd/section.c

   1 /* Object file "section" support for the BFD library.
   2    Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
   3    Written by Cygnus Support.
   4
   5 This file is part of BFD, the Binary File Descriptor library.
   6
   7 This program is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program; if not, write to the Free Software
  19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 /*
  22 SECTION
  23         Sections
  24
  25         The raw data contained within a BFD is maintained through the
  26         section abstraction.  A single BFD may have any number of
  27         sections.  It keeps hold of them by pointing to the first;
  28         each one points to the next in the list.
  29
  30         Sections are supported in BFD in <<section.c>>.
  31
  32 @menu
  33 @* Section Input::
  34 @* Section Output::
  35 @* typedef asection::
  36 @* section prototypes::
  37 @end menu
  38
  39 INODE
  40 Section Input, Section Output, Sections, Sections
  41 SUBSECTION
  42         Section input
  43
  44         When a BFD is opened for reading, the section structures are
  45         created and attached to the BFD.
  46
  47         Each section has a name which describes the section in the
  48         outside world---for example, <<a.out>> would contain at least
  49         three sections, called <<.text>>, <<.data>> and <<.bss>>.
  50
  51         Names need not be unique; for example a COFF file may have several
  52         sections named <<.data>>.
  53
  54         Sometimes a BFD will contain more than the ``natural'' number of
  55         sections. A back end may attach other sections containing
  56         constructor data, or an application may add a section (using
  57         <<bfd_make_section>>) to the sections attached to an already open
  58         BFD. For example, the linker creates an extra section
  59         <<COMMON>> for each input file's BFD to hold information about
  60         common storage.
  61
  62         The raw data is not necessarily read in when
  63         the section descriptor is created. Some targets may leave the
  64         data in place until a <<bfd_get_section_contents>> call is
  65         made. Other back ends may read in all the data at once.  For
  66         example, an S-record file has to be read once to determine the
  67         size of the data. An IEEE-695 file doesn't contain raw data in
  68         sections, but data and relocation expressions intermixed, so
  69         the data area has to be parsed to get out the data and
  70         relocations.
  71
  72 INODE
  73 Section Output, typedef asection, Section Input, Sections
  74
  75 SUBSECTION
  76         Section output
  77
  78         To write a new object style BFD, the various sections to be
  79         written have to be created. They are attached to the BFD in
  80         the same way as input sections; data is written to the
  81         sections using <<bfd_set_section_contents>>.
  82
  83         Any program that creates or combines sections (e.g., the assembler
  84         and linker) must use the <<asection>> fields <<output_section>> and
  85         <<output_offset>> to indicate the file sections to which each
  86         section must be written.  (If the section is being created from
  87         scratch, <<output_section>> should probably point to the section
  88         itself and <<output_offset>> should probably be zero.)
  89
  90         The data to be written comes from input sections attached
  91         (via <<output_section>> pointers) to
  92         the output sections.  The output section structure can be
  93         considered a filter for the input section: the output section
  94         determines the vma of the output data and the name, but the
  95         input section determines the offset into the output section of
  96         the data to be written.
  97
  98         E.g., to create a section "O", starting at 0x100, 0x123 long,
  99         containing two subsections, "A" at offset 0x0 (i.e., at vma
 100         0x100) and "B" at offset 0x20 (i.e., at vma 0x120) the <<asection>>
 101         structures would look like:
 102
 103 |   section name          "A"
 104 |     output_offset   0x00
 105 |     size            0x20
 106 |     output_section ----------->  section name    "O"
 107 |                             |    vma             0x100
 108 |   section name          "B" |    size            0x123
 109 |     output_offset   0x20    |
 110 |     size            0x103   |
 111 |     output_section  --------|
 112
 113
 114 SUBSECTION
 115         Link orders
 116
 117         The data within a section is stored in a @dfn{link_order}.
 118         These are much like the fixups in <<gas>>.  The link_order
 119         abstraction allows a section to grow and shrink within itself.
 120
 121         A link_order knows how big it is, and which is the next
 122         link_order and where the raw data for it is; it also points to
 123         a list of relocations which apply to it.
 124
 125         The link_order is used by the linker to perform relaxing on
 126         final code.  The compiler creates code which is as big as
 127         necessary to make it work without relaxing, and the user can
 128         select whether to relax.  Sometimes relaxing takes a lot of
 129         time.  The linker runs around the relocations to see if any
 130         are attached to data which can be shrunk, if so it does it on
 131         a link_order by link_order basis.
 132
 133 */
 134
 135
 136 #include "bfd.h"
 137 #include "sysdep.h"
 138 #include "libbfd.h"
 139
 140
 141 /*
 142 DOCDD
 143 INODE
 144 typedef asection, section prototypes, Section Output, Sections
 145 SUBSECTION
 146         typedef asection
 147
 148         Here is the section structure:
 149
 150 CODE_FRAGMENT
 151 .
 152 .typedef struct sec
 153 .{
 154 .        {* The name of the section; the name isn't a copy, the pointer is
 155 .        the same as that passed to bfd_make_section. *}
 156 .
 157 .    CONST char *name;
 158 .
 159 .        {* Which section is it; 0..nth.      *}
 160 .
 161 .   int index;
 162 .
 163 .        {* The next section in the list belonging to the BFD, or NULL. *}
 164 .
 165 .    struct sec *next;
 166 .
 167 .        {* The field flags contains attributes of the section. Some
 168 .           flags are read in from the object file, and some are
 169 .           synthesized from other information.  *}
 170 .
 171 .    flagword flags;
 172 .
 173 .#define SEC_NO_FLAGS   0x000
 174 .
 175 .        {* Tells the OS to allocate space for this section when loading.
 176 .           This is clear for a section containing debug information
 177 .           only. *}
 178 .#define SEC_ALLOC      0x001
 179 .
 180 .        {* Tells the OS to load the section from the file when loading.
 181 .           This is clear for a .bss section. *}
 182 .#define SEC_LOAD       0x002
 183 .
 184 .        {* The section contains data still to be relocated, so there is
 185 .           some relocation information too. *}
 186 .#define SEC_RELOC      0x004
 187 .
 188 .#if 0   {* Obsolete ? *}
 189 .#define SEC_BALIGN     0x008
 190 .#endif
 191 .
 192 .        {* A signal to the OS that the section contains read only
 193 .          data. *}
 194 .#define SEC_READONLY   0x010
 195 .
 196 .        {* The section contains code only. *}
 197 .#define SEC_CODE       0x020
 198 .
 199 .        {* The section contains data only. *}
 200 .#define SEC_DATA       0x040
 201 .
 202 .        {* The section will reside in ROM. *}
 203 .#define SEC_ROM        0x080
 204 .
 205 .        {* The section contains constructor information. This section
 206 .           type is used by the linker to create lists of constructors and
 207 .           destructors used by <<g++>>. When a back end sees a symbol
 208 .           which should be used in a constructor list, it creates a new
 209 .           section for the type of name (e.g., <<__CTOR_LIST__>>), attaches
 210 .           the symbol to it, and builds a relocation. To build the lists
 211 .           of constructors, all the linker has to do is catenate all the
 212 .           sections called <<__CTOR_LIST__>> and relocate the data
 213 .           contained within - exactly the operations it would peform on
 214 .           standard data. *}
 215 .#define SEC_CONSTRUCTOR 0x100
 216 .
 217 .        {* The section is a constuctor, and should be placed at the
 218 .          end of the text, data, or bss section(?). *}
 219 .#define SEC_CONSTRUCTOR_TEXT 0x1100
 220 .#define SEC_CONSTRUCTOR_DATA 0x2100
 221 .#define SEC_CONSTRUCTOR_BSS  0x3100
 222 .
 223 .        {* The section has contents - a data section could be
 224 .           <<SEC_ALLOC>> | <<SEC_HAS_CONTENTS>>; a debug section could be
 225 .           <<SEC_HAS_CONTENTS>> *}
 226 .#define SEC_HAS_CONTENTS 0x200
 227 .
 228 .        {* An instruction to the linker to not output the section
 229 .          even if it has information which would normally be written. *}
 230 .#define SEC_NEVER_LOAD 0x400
 231 .
 232 .        {* The section is a shared library section.  The linker must leave
 233 .           these completely alone, as the vma and size are used when
 234 .           the executable is loaded. *}
 235 .#define SEC_SHARED_LIBRARY 0x800
 236 .
 237 .        {* The section is a common section (symbols may be defined
 238 .           multiple times, the value of a symbol is the amount of
 239 .           space it requires, and the largest symbol value is the one
 240 .           used).  Most targets have exactly one of these (which we
 241 .           translate to bfd_com_section), but ECOFF has two. *}
 242 .#define SEC_IS_COMMON 0x8000
 243 .
 244 .        {* The section contains only debugging information.  For
 245 .           example, this is set for ELF .debug and .stab sections.
 246 .           strip tests this flag to see if a section can be
 247 .           discarded. *}
 248 .#define SEC_DEBUGGING 0x10000
 249 .
 250 .       {*  End of section flags.  *}
 251 .
 252 .       {*  The virtual memory address of the section - where it will be
 253 .           at run time.  The symbols are relocated against this.  The
 254 .           user_set_vma flag is maintained by bfd; if it's not set, the
 255 .           backend can assign addresses (for example, in <<a.out>>, where
 256 .           the default address for <<.data>> is dependent on the specific
 257 .           target and various flags).  *}
 258 .
 259 .   bfd_vma vma;
 260 .   boolean user_set_vma;
 261 .
 262 .       {*  The load address of the section - where it would be in a
 263 .           rom image; really only used for writing section header
 264 .           information. *}
 265 .
 266 .   bfd_vma lma;
 267 .
 268 .        {* The size of the section in bytes, as it will be output.
 269 .           contains a value even if the section has no contents (e.g., the
 270 .           size of <<.bss>>). This will be filled in after relocation *}
 271 .
 272 .   bfd_size_type _cooked_size;
 273 .
 274 .        {* The original size on disk of the section, in bytes.  Normally this
 275 .           value is the same as the size, but if some relaxing has
 276 .           been done, then this value will be bigger.  *}
 277 .
 278 .   bfd_size_type _raw_size;
 279 .
 280 .        {* If this section is going to be output, then this value is the
 281 .           offset into the output section of the first byte in the input
 282 .           section. E.g., if this was going to start at the 100th byte in
 283 .           the output section, this value would be 100. *}
 284 .
 285 .   bfd_vma output_offset;
 286 .
 287 .        {* The output section through which to map on output. *}
 288 .
 289 .   struct sec *output_section;
 290 .
 291 .        {* The alignment requirement of the section, as an exponent of 2 -
 292 .           e.g., 3 aligns to 2^3 (or 8). *}
 293 .
 294 .   unsigned int alignment_power;
 295 .
 296 .        {* If an input section, a pointer to a vector of relocation
 297 .           records for the data in this section. *}
 298 .
 299 .   struct reloc_cache_entry *relocation;
 300 .
 301 .        {* If an output section, a pointer to a vector of pointers to
 302 .           relocation records for the data in this section. *}
 303 .
 304 .   struct reloc_cache_entry **orelocation;
 305 .
 306 .        {* The number of relocation records in one of the above  *}
 307 .
 308 .   unsigned reloc_count;
 309 .
 310 .        {* Information below is back end specific - and not always used
 311 .           or updated.  *}
 312 .
 313 .        {* File position of section data    *}
 314 .
 315 .   file_ptr filepos;
 316 .
 317 .        {* File position of relocation info *}
 318 .
 319 .   file_ptr rel_filepos;
 320 .
 321 .        {* File position of line data       *}
 322 .
 323 .   file_ptr line_filepos;
 324 .
 325 .        {* Pointer to data for applications *}
 326 .
 327 .   PTR userdata;
 328 .
 329 .   struct lang_output_section *otheruserdata;
 330 .
 331 .        {* Attached line number information *}
 332 .
 333 .   alent *lineno;
 334 .
 335 .        {* Number of line number records   *}
 336 .
 337 .   unsigned int lineno_count;
 338 .
 339 .        {* When a section is being output, this value changes as more
 340 .           linenumbers are written out *}
 341 .
 342 .   file_ptr moving_line_filepos;
 343 .
 344 .        {* What the section number is in the target world  *}
 345 .
 346 .   int target_index;
 347 .
 348 .   PTR used_by_bfd;
 349 .
 350 .        {* If this is a constructor section then here is a list of the
 351 .           relocations created to relocate items within it. *}
 352 .
 353 .   struct relent_chain *constructor_chain;
 354 .
 355 .        {* The BFD which owns the section. *}
 356 .
 357 .   bfd *owner;
 358 .
 359 .   boolean reloc_done;
 360 .        {* A symbol which points at this section only *}
 361 .   struct symbol_cache_entry *symbol;
 362 .   struct symbol_cache_entry **symbol_ptr_ptr;
 363 .
 364 .   struct bfd_link_order *link_order_head;
 365 .   struct bfd_link_order *link_order_tail;
 366 .} asection ;
 367 .
 368 .
 369 .    {* These sections are global, and are managed by BFD.  The application
 370 .       and target back end are not permitted to change the values in
 371 .       these sections.  *}
 372 .#define BFD_ABS_SECTION_NAME "*ABS*"
 373 .#define BFD_UND_SECTION_NAME "*UND*"
 374 .#define BFD_COM_SECTION_NAME "*COM*"
 375 .#define BFD_IND_SECTION_NAME "*IND*"
 376 .
 377 .    {* the absolute section *}
 378 .extern asection bfd_abs_section;
 379 .    {* Pointer to the undefined section *}
 380 .extern asection bfd_und_section;
 381 .    {* Pointer to the common section *}
 382 .extern asection bfd_com_section;
 383 .    {* Pointer to the indirect section *}
 384 .extern asection bfd_ind_section;
 385 .
 386 .extern struct symbol_cache_entry *bfd_abs_symbol;
 387 .extern struct symbol_cache_entry *bfd_com_symbol;
 388 .extern struct symbol_cache_entry *bfd_und_symbol;
 389 .extern struct symbol_cache_entry *bfd_ind_symbol;
 390 .#define bfd_get_section_size_before_reloc(section) \
 391 .     (section->reloc_done ? (abort(),1): (section)->_raw_size)
 392 .#define bfd_get_section_size_after_reloc(section) \
 393 .     ((section->reloc_done) ? (section)->_cooked_size: (abort(),1))
 394 */
 395
 396 /* These symbols are global, not specific to any BFD.  Therefore, anything
 397    that tries to change them is broken, and should be repaired.  */
 398 static CONST asymbol global_syms[] = {
 399   /* the_bfd, name, value, attr, section [, udata] */
 400   { 0, BFD_COM_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_com_section },
 401   { 0, BFD_UND_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_und_section },
 402   { 0, BFD_ABS_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_abs_section },
 403   { 0, BFD_IND_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_ind_section },
 404 };
 405
 406 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
 407   asymbol *SYM = (asymbol *) &global_syms[IDX]; \
 408   asection SEC = { NAME, 0, 0, FLAGS, 0, 0, (boolean) 0, 0, 0, 0, &SEC,\
 409                     0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0, (boolean) 0, \
 410                      (asymbol *) &global_syms[IDX], &SYM, }
 411
 412 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol, BFD_COM_SECTION_NAME, 0);
 413 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
 414 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
 415 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
 416 #undef STD_SECTION
 417
 418 /*
 419 DOCDD
 420 INODE
 421 section prototypes,  , typedef asection, Sections
 422 SUBSECTION
 423         Section prototypes
 424
 425 These are the functions exported by the section handling part of BFD.
 426 */
 427
 428 /*
 429 FUNCTION
 430         bfd_get_section_by_name
 431
 432 SYNOPSIS
 433         asection *bfd_get_section_by_name(bfd *abfd, CONST char *name);
 434
 435 DESCRIPTION
 436         Run through @var{abfd} and return the one of the
 437         <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
 438         @xref{Sections}, for more information.
 439
 440         This should only be used in special cases; the normal way to process
 441         all sections of a given name is to use <<bfd_map_over_sections>> and
 442         <<strcmp>> on the name (or better yet, base it on the section flags
 443         or something else) for each section.
 444 */
 445
 446 asection *
 447 DEFUN(bfd_get_section_by_name,(abfd, name),
 448       bfd *abfd AND
 449       CONST char *name)
 450 {
 451   asection *sect;
 452
 453   for (sect = abfd->sections; sect != NULL; sect = sect->next)
 454     if (!strcmp (sect->name, name)) return sect;
 455   return NULL;
 456 }
 457
 458
 459 /*
 460 FUNCTION
 461         bfd_make_section_old_way
 462
 463 SYNOPSIS
 464         asection *bfd_make_section_old_way(bfd *abfd, CONST char *name);
 465
 466 DESCRIPTION
 467         Create a new empty section called @var{name}
 468         and attach it to the end of the chain of sections for the
 469         BFD @var{abfd}. An attempt to create a section with a name which
 470         is already in use returns its pointer without changing the
 471         section chain.
 472
 473         It has the funny name since this is the way it used to be
 474         before it was rewritten....
 475
 476         Possible errors are:
 477         o <<invalid_operation>> -
 478         If output has already started for this BFD.
 479         o <<no_memory>> -
 480         If obstack alloc fails.
 481
 482 */
 483
 484
 485 asection *
 486 DEFUN(bfd_make_section_old_way,(abfd, name),
 487       bfd *abfd AND
 488       CONST char * name)
 489 {
 490   asection *sec = bfd_get_section_by_name(abfd, name);
 491   if (sec == (asection *)NULL)
 492     {
 493       sec = bfd_make_section(abfd, name);
 494     }
 495   return sec;
 496 }
 497
 498 /*
 499 FUNCTION
 500         bfd_make_section_anyway
 501
 502 SYNOPSIS
 503         asection *bfd_make_section_anyway(bfd *abfd, CONST char *name);
 504
 505 DESCRIPTION
 506    Create a new empty section called @var{name} and attach it to the end of
 507    the chain of sections for @var{abfd}.  Create a new section even if there
 508    is already a section with that name.
 509
 510    Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
 511    o <<invalid_operation>> - If output has already started for @var{abfd}.
 512    o <<no_memory>> - If obstack alloc fails.
 513 */
 514
 515 sec_ptr
 516 bfd_make_section_anyway (abfd, name)
 517      bfd *abfd;
 518      CONST char *name;
 519 {
 520   asection *newsect;
 521   asection **prev = &abfd->sections;
 522   asection * sect = abfd->sections;
 523
 524   if (abfd->output_has_begun)
 525     {
 526       bfd_error = invalid_operation;
 527       return NULL;
 528     }
 529
 530   while (sect) {
 531     prev = &sect->next;
 532     sect = sect->next;
 533   }
 534
 535   newsect = (asection *) bfd_zalloc(abfd, sizeof (asection));
 536   if (newsect == NULL) {
 537     bfd_error = no_memory;
 538     return NULL;
 539   }
 540
 541   newsect->name = name;
 542   newsect->index = abfd->section_count++;
 543   newsect->flags = SEC_NO_FLAGS;
 544
 545   newsect->userdata = 0;
 546   newsect->next = (asection *)NULL;
 547   newsect->relocation = (arelent *)NULL;
 548   newsect->reloc_count = 0;
 549   newsect->line_filepos =0;
 550   newsect->owner = abfd;
 551
 552   /* Create a symbol whos only job is to point to this section. This is
 553      useful for things like relocs which are relative to the base of a
 554      section.  */
 555   newsect->symbol = bfd_make_empty_symbol(abfd);
 556   newsect->symbol->name = name;
 557   newsect->symbol->value = 0;
 558   newsect->symbol->section = newsect;
 559   newsect->symbol->flags = BSF_SECTION_SYM;
 560
 561   newsect->symbol_ptr_ptr = &newsect->symbol;
 562
 563   if (BFD_SEND (abfd, _new_section_hook, (abfd, newsect)) != true) {
 564     free (newsect);
 565     return NULL;
 566   }
 567
 568   *prev = newsect;
 569   return newsect;
 570 }
 571
 572 /*
 573 FUNCTION
 574         bfd_make_section
 575
 576 SYNOPSIS
 577         asection *bfd_make_section(bfd *, CONST char *name);
 578
 579 DESCRIPTION
 580    Like <<bfd_make_section_anyway>>, but return <<NULL>> (without setting
 581    bfd_error) without changing the section chain if there is already a
 582    section named @var{name}.  If there is an error, return <<NULL>> and set
 583    <<bfd_error>>.
 584 */
 585
 586 sec_ptr
 587 DEFUN(bfd_make_section,(abfd, name),
 588       bfd *abfd AND
 589       CONST char * name)
 590 {
 591   asection * sect = abfd->sections;
 592
 593   if (strcmp(name, BFD_ABS_SECTION_NAME) == 0)
 594   {
 595     return &bfd_abs_section;
 596   }
 597   if (strcmp(name, BFD_COM_SECTION_NAME) == 0)
 598   {
 599     return &bfd_com_section;
 600   }
 601   if (strcmp(name, BFD_UND_SECTION_NAME) == 0)
 602   {
 603     return &bfd_und_section;
 604   }
 605
 606   if (strcmp(name, BFD_IND_SECTION_NAME) == 0)
 607   {
 608     return &bfd_ind_section;
 609   }
 610
 611   while (sect) {
 612     if (!strcmp(sect->name, name)) return NULL;
 613     sect = sect->next;
 614   }
 615
 616   /* The name is not already used; go ahead and make a new section.  */
 617   return bfd_make_section_anyway (abfd, name);
 618 }
 619
 620
 621 /*
 622 FUNCTION
 623         bfd_set_section_flags
 624
 625 SYNOPSIS
 626         boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags);
 627
 628 DESCRIPTION
 629         Set the attributes of the section @var{sec} in the BFD
 630         @var{abfd} to the value @var{flags}. Return <<true>> on success,
 631         <<false>> on error. Possible error returns are:
 632
 633         o <<invalid_operation>> -
 634         The section cannot have one or more of the attributes
 635         requested. For example, a .bss section in <<a.out>> may not
 636         have the <<SEC_HAS_CONTENTS>> field set.
 637
 638 */
 639
 640 boolean
 641 DEFUN(bfd_set_section_flags,(abfd, section, flags),
 642      bfd *abfd AND
 643      sec_ptr section AND
 644      flagword flags)
 645 {
 646 #if 0
 647   /* If you try to copy a text section from an input file (where it
 648      has the SEC_CODE flag set) to an output file, this loses big if
 649      the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
 650      set - which it doesn't, at least not for a.out.  FIXME */
 651
 652   if ((flags & bfd_applicable_section_flags (abfd)) != flags) {
 653     bfd_error = invalid_operation;
 654     return false;
 655   }
 656 #endif
 657
 658   section->flags = flags;
 659   return true;
 660 }
 661
 662
 663 /*
 664 FUNCTION
 665         bfd_map_over_sections
 666
 667 SYNOPSIS
 668         void bfd_map_over_sections(bfd *abfd,
 669                                    void (*func)(bfd *abfd,
 670                                                 asection *sect,
 671                                                 PTR obj),
 672                                    PTR obj);
 673
 674 DESCRIPTION
 675         Call the provided function @var{func} for each section
 676         attached to the BFD @var{abfd}, passing @var{obj} as an
 677         argument. The function will be called as if by
 678
 679 |       func(abfd, the_section, obj);
 680
 681         This is the prefered method for iterating over sections; an
 682         alternative would be to use a loop:
 683
 684 |          section *p;
 685 |          for (p = abfd->sections; p != NULL; p = p->next)
 686 |             func(abfd, p, ...)
 687
 688
 689 */
 690
 691 /*VARARGS2*/
 692 void
 693 DEFUN(bfd_map_over_sections,(abfd, operation, user_storage),
 694       bfd *abfd AND
 695       void (*operation) PARAMS ((bfd *abfd, asection *sect, PTR obj)) AND
 696       PTR user_storage)
 697 {
 698   asection *sect;
 699   int i = 0;
 700
 701   for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
 702     (*operation) (abfd, sect, user_storage);
 703
 704   if (i != abfd->section_count)         /* Debugging */
 705     abort();
 706 }
 707
 708
 709 /*
 710 FUNCTION
 711         bfd_set_section_size
 712
 713 SYNOPSIS
 714         boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val);
 715
 716 DESCRIPTION
 717         Set @var{sec} to the size @var{val}. If the operation is
 718         ok, then <<true>> is returned, else <<false>>.
 719
 720         Possible error returns:
 721         o <<invalid_operation>> -
 722         Writing has started to the BFD, so setting the size is invalid.
 723
 724 */
 725
 726 boolean
 727 DEFUN(bfd_set_section_size,(abfd, ptr, val),
 728       bfd *abfd AND
 729       sec_ptr ptr AND
 730       bfd_size_type val)
 731 {
 732   /* Once you've started writing to any section you cannot create or change
 733      the size of any others. */
 734
 735   if (abfd->output_has_begun) {
 736     bfd_error = invalid_operation;
 737     return false;
 738   }
 739
 740   ptr->_cooked_size = val;
 741   ptr->_raw_size = val;
 742
 743   return true;
 744 }
 745
 746 /*
 747 FUNCTION
 748         bfd_set_section_contents
 749
 750 SYNOPSIS
 751         boolean bfd_set_section_contents
 752          (bfd *abfd,
 753          asection *section,
 754          PTR data,
 755          file_ptr offset,
 756          bfd_size_type count);
 757
 758
 759 DESCRIPTION
 760         Sets the contents of the section @var{section} in BFD
 761         @var{abfd} to the data starting in memory at @var{data}. The
 762         data is written to the output section starting at offset
 763         @var{offset} for @var{count} bytes.
 764
 765
 766
 767         Normally <<true>> is returned, else <<false>>. Possible error
 768         returns are:
 769         o <<no_contents>> -
 770         The output section does not have the <<SEC_HAS_CONTENTS>>
 771         attribute, so nothing can be written to it.
 772         o and some more too
 773
 774         This routine is front end to the back end function
 775         <<_bfd_set_section_contents>>.
 776
 777
 778 */
 779
 780 #define bfd_get_section_size_now(abfd,sec) \
 781 (sec->reloc_done \
 782  ? bfd_get_section_size_after_reloc (sec) \
 783  : bfd_get_section_size_before_reloc (sec))
 784
 785 boolean
 786 DEFUN(bfd_set_section_contents,(abfd, section, location, offset, count),
 787       bfd *abfd AND
 788       sec_ptr section AND
 789       PTR location AND
 790       file_ptr offset AND
 791       bfd_size_type count)
 792 {
 793   bfd_size_type sz;
 794
 795   if (!bfd_get_section_flags(abfd, section) & SEC_HAS_CONTENTS)
 796       {
 797         bfd_error = no_contents;
 798         return(false);
 799       }
 800
 801   if (offset < 0)
 802     {
 803     bad_val:
 804       bfd_error = bad_value;
 805       return false;
 806     }
 807   sz = bfd_get_section_size_now (abfd, section);
 808   if (offset > sz
 809       || count > sz
 810       || offset + count > sz)
 811     goto bad_val;
 812
 813   switch (abfd->direction)
 814     {
 815       case read_direction:
 816       case no_direction:
 817         bfd_error = invalid_operation;
 818         return false;
 819
 820       case write_direction:
 821         break;
 822
 823       case both_direction:
 824         /* File is opened for update. `output_has_begun' some time ago when
 825            the file was created.  Do not recompute sections sizes or alignments
 826            in _bfd_set_section_content.  */
 827         abfd->output_has_begun = true;
 828         break;
 829     }
 830
 831   if (BFD_SEND (abfd, _bfd_set_section_contents,
 832                 (abfd, section, location, offset, count)))
 833       {
 834         abfd->output_has_begun = true;
 835         return true;
 836       }
 837
 838   return false;
 839 }
 840
 841 /*
 842 FUNCTION
 843         bfd_get_section_contents
 844
 845 SYNOPSIS
 846         boolean bfd_get_section_contents
 847         (bfd *abfd, asection *section, PTR location,
 848          file_ptr offset, bfd_size_type count);
 849
 850 DESCRIPTION
 851         Read data from @var{section} in BFD @var{abfd}
 852         into memory starting at @var{location}. The data is read at an
 853         offset of @var{offset} from the start of the input section,
 854         and is read for @var{count} bytes.
 855
 856         If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
 857         flag set are requested or if the section does not have the
 858         <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
 859         with zeroes. If no errors occur, <<true>> is returned, else
 860         <<false>>.
 861
 862
 863
 864 */
 865 boolean
 866 DEFUN(bfd_get_section_contents,(abfd, section, location, offset, count),
 867       bfd *abfd AND
 868       sec_ptr section AND
 869       PTR location AND
 870       file_ptr offset AND
 871       bfd_size_type count)
 872 {
 873   bfd_size_type sz;
 874
 875   if (section->flags & SEC_CONSTRUCTOR)
 876     {
 877       memset(location, 0, (unsigned)count);
 878       return true;
 879     }
 880
 881   if (offset < 0)
 882     {
 883     bad_val:
 884       bfd_error = bad_value;
 885       return false;
 886     }
 887   sz = bfd_get_section_size_now (abfd, section);
 888   if (offset > sz
 889       || count > sz
 890       || offset + count > sz)
 891     goto bad_val;
 892
 893   if (count == 0)
 894     /* Don't bother.  */
 895     return true;
 896
 897   if ((section->flags & SEC_HAS_CONTENTS) == 0)
 898     {
 899       memset(location, 0, (unsigned)count);
 900       return true;
 901     }
 902
 903   return BFD_SEND (abfd, _bfd_get_section_contents,
 904                    (abfd, section, location, offset, count));
 905 }