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         Seclets
 116
 117         The data within a section is stored in a <<seclet>>.  These
 118         are much like the fixups in <<gas>>.  The seclet abstraction
 119         allows a section to grow and shrink within itself.
 120
 121         A seclet knows how big it is, and which is the next seclet and
 122         where the raw data for it is; it also points to a list of
 123         relocations which apply to it.
 124
 125         The seclet is used by the linker to perform relaxing on final
 126         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 seclet by seclet 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_seclet *seclets_head;
 365 .   struct bfd_seclet *seclets_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
 426 <<libbfd>>.
 427 */
 428
 429 /*
 430 FUNCTION
 431         bfd_get_section_by_name
 432
 433 SYNOPSIS
 434         asection *bfd_get_section_by_name(bfd *abfd, CONST char *name);
 435
 436 DESCRIPTION
 437         Run through the provided @var{abfd} and return the one of the
 438         <<asection>>s whose name matches @var{name}, otherwise NULL.
 439         @xref{Sections}, for more information.
 440
 441         This should only be used in special cases; the normal way to process
 442         all sections of a given name is to use bfd_map_over_sections and
 443         strcmp on the name (or better yet, base it on the section flags
 444         or something else) for each section.
 445 */
 446
 447 asection *
 448 DEFUN(bfd_get_section_by_name,(abfd, name),
 449       bfd *abfd AND
 450       CONST char *name)
 451 {
 452   asection *sect;
 453
 454   for (sect = abfd->sections; sect != NULL; sect = sect->next)
 455     if (!strcmp (sect->name, name)) return sect;
 456   return NULL;
 457 }
 458
 459
 460 /*
 461 FUNCTION
 462         bfd_make_section_old_way
 463
 464 SYNOPSIS
 465         asection *bfd_make_section_old_way(bfd *abfd, CONST char *name);
 466
 467 DESCRIPTION
 468         Create a new empty section called @var{name}
 469         and attach it to the end of the chain of sections for the
 470         BFD @var{abfd}. An attempt to create a section with a name which
 471         is already in use, returns its pointer without changing the
 472         section chain.
 473
 474         It has the funny name since this is the way it used to be
 475         before it was rewritten....
 476
 477         Possible errors are:
 478         o invalid_operation -
 479         If output has already started for this BFD.
 480         o no_memory -
 481         If obstack alloc fails.
 482
 483 */
 484
 485
 486 asection *
 487 DEFUN(bfd_make_section_old_way,(abfd, name),
 488       bfd *abfd AND
 489       CONST char * name)
 490 {
 491   asection *sec = bfd_get_section_by_name(abfd, name);
 492   if (sec == (asection *)NULL)
 493     {
 494       sec = bfd_make_section(abfd, name);
 495     }
 496   return sec;
 497 }
 498
 499 /*
 500 FUNCTION
 501         bfd_make_section_anyway
 502
 503 SYNOPSIS
 504         asection *bfd_make_section_anyway(bfd *abfd, CONST char *name);
 505
 506 DESCRIPTION
 507    Create a new empty section called @var{name} and attach it to the end of
 508    the chain of sections for @var{abfd}.  Create a new section even if there
 509    is already a section with that name.
 510
 511    Returns NULL and sets bfd_error on error; possible errors are:
 512    o invalid_operation - If output has already started for @var{abfd}.
 513    o no_memory - If obstack alloc fails.
 514 */
 515
 516 sec_ptr
 517 bfd_make_section_anyway (abfd, name)
 518      bfd *abfd;
 519      CONST char *name;
 520 {
 521   asection *newsect;
 522   asection **prev = &abfd->sections;
 523   asection * sect = abfd->sections;
 524
 525   if (abfd->output_has_begun)
 526     {
 527       bfd_error = invalid_operation;
 528       return NULL;
 529     }
 530
 531   while (sect) {
 532     prev = &sect->next;
 533     sect = sect->next;
 534   }
 535
 536   newsect = (asection *) bfd_zalloc(abfd, sizeof (asection));
 537   if (newsect == NULL) {
 538     bfd_error = no_memory;
 539     return NULL;
 540   }
 541
 542   newsect->name = name;
 543   newsect->index = abfd->section_count++;
 544   newsect->flags = SEC_NO_FLAGS;
 545
 546   newsect->userdata = 0;
 547   newsect->next = (asection *)NULL;
 548   newsect->relocation = (arelent *)NULL;
 549   newsect->reloc_count = 0;
 550   newsect->line_filepos =0;
 551   newsect->owner = abfd;
 552
 553   /* Create a symbol whos only job is to point to this section. This is
 554      useful for things like relocs which are relative to the base of a
 555      section.  */
 556   newsect->symbol = bfd_make_empty_symbol(abfd);
 557   newsect->symbol->name = name;
 558   newsect->symbol->value = 0;
 559   newsect->symbol->section = newsect;
 560   newsect->symbol->flags = BSF_SECTION_SYM;
 561
 562   newsect->symbol_ptr_ptr = &newsect->symbol;
 563
 564   if (BFD_SEND (abfd, _new_section_hook, (abfd, newsect)) != true) {
 565     free (newsect);
 566     return NULL;
 567   }
 568
 569   *prev = newsect;
 570   return newsect;
 571 }
 572
 573 /*
 574 FUNCTION
 575         bfd_make_section
 576
 577 SYNOPSIS
 578         asection *bfd_make_section(bfd *, CONST char *name);
 579
 580 DESCRIPTION
 581    Like <<bfd_make_section_anyway>>, but return NULL (without setting
 582    bfd_error) without changing the section chain if there is already a
 583    section named @var{name}.  If there is an error, return NULL and set
 584    bfd_error.
 585 */
 586
 587 sec_ptr
 588 DEFUN(bfd_make_section,(abfd, name),
 589       bfd *abfd AND
 590       CONST char * name)
 591 {
 592   asection * sect = abfd->sections;
 593
 594   if (strcmp(name, BFD_ABS_SECTION_NAME) == 0)
 595   {
 596     return &bfd_abs_section;
 597   }
 598   if (strcmp(name, BFD_COM_SECTION_NAME) == 0)
 599   {
 600     return &bfd_com_section;
 601   }
 602   if (strcmp(name, BFD_UND_SECTION_NAME) == 0)
 603   {
 604     return &bfd_und_section;
 605   }
 606
 607   if (strcmp(name, BFD_IND_SECTION_NAME) == 0)
 608   {
 609     return &bfd_ind_section;
 610   }
 611
 612   while (sect) {
 613     if (!strcmp(sect->name, name)) return NULL;
 614     sect = sect->next;
 615   }
 616
 617   /* The name is not already used; go ahead and make a new section.  */
 618   return bfd_make_section_anyway (abfd, name);
 619 }
 620
 621
 622 /*
 623 FUNCTION
 624         bfd_set_section_flags
 625
 626 SYNOPSIS
 627         boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags);
 628
 629 DESCRIPTION
 630         Set the attributes of the section @var{sec} in the BFD
 631         @var{abfd} to the value @var{flags}. Returns <<true>> on success,
 632         <<false>> on error. Possible error returns are:
 633
 634         o invalid operation -
 635         The section cannot have one or more of the attributes
 636         requested. For example, a .bss section in <<a.out>> may not
 637         have the <<SEC_HAS_CONTENTS>> field set.
 638
 639 */
 640
 641 boolean
 642 DEFUN(bfd_set_section_flags,(abfd, section, flags),
 643      bfd *abfd AND
 644      sec_ptr section AND
 645      flagword flags)
 646 {
 647 #if 0
 648   /* If you try to copy a text section from an input file (where it
 649      has the SEC_CODE flag set) to an output file, this loses big if
 650      the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
 651      set - which it doesn't, at least not for a.out.  FIXME */
 652
 653   if ((flags & bfd_applicable_section_flags (abfd)) != flags) {
 654     bfd_error = invalid_operation;
 655     return false;
 656   }
 657 #endif
 658
 659   section->flags = flags;
 660   return true;
 661 }
 662
 663
 664 /*
 665 FUNCTION
 666         bfd_map_over_sections
 667
 668 SYNOPSIS
 669         void bfd_map_over_sections(bfd *abfd,
 670                                    void (*func)(bfd *abfd,
 671                                                 asection *sect,
 672                                                 PTR obj),
 673                                    PTR obj);
 674
 675 DESCRIPTION
 676         Call the provided function @var{func} for each section
 677         attached to the BFD @var{abfd}, passing @var{obj} as an
 678         argument. The function will be called as if by
 679
 680 |       func(abfd, the_section, obj);
 681
 682         This is the prefered method for iterating over sections; an
 683         alternative would be to use a loop:
 684
 685 |          section *p;
 686 |          for (p = abfd->sections; p != NULL; p = p->next)
 687 |             func(abfd, p, ...)
 688
 689
 690 */
 691
 692 /*VARARGS2*/
 693 void
 694 DEFUN(bfd_map_over_sections,(abfd, operation, user_storage),
 695       bfd *abfd AND
 696       void (*operation) PARAMS ((bfd *abfd, asection *sect, PTR obj)) AND
 697       PTR user_storage)
 698 {
 699   asection *sect;
 700   int i = 0;
 701
 702   for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
 703     (*operation) (abfd, sect, user_storage);
 704
 705   if (i != abfd->section_count)         /* Debugging */
 706     abort();
 707 }
 708
 709
 710 /*
 711 FUNCTION
 712         bfd_set_section_size
 713
 714 SYNOPSIS
 715         boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val);
 716
 717 DESCRIPTION
 718         Set @var{sec} to the size @var{val}. If the operation is
 719         ok, then <<true>> is returned, else <<false>>.
 720
 721         Possible error returns:
 722         o invalid_operation -
 723         Writing has started to the BFD, so setting the size is invalid
 724
 725 */
 726
 727 boolean
 728 DEFUN(bfd_set_section_size,(abfd, ptr, val),
 729       bfd *abfd AND
 730       sec_ptr ptr AND
 731       bfd_size_type val)
 732 {
 733   /* Once you've started writing to any section you cannot create or change
 734      the size of any others. */
 735
 736   if (abfd->output_has_begun) {
 737     bfd_error = invalid_operation;
 738     return false;
 739   }
 740
 741   ptr->_cooked_size = val;
 742   ptr->_raw_size = val;
 743
 744   return true;
 745 }
 746
 747 /*
 748 FUNCTION
 749         bfd_set_section_contents
 750
 751 SYNOPSIS
 752         boolean bfd_set_section_contents
 753          (bfd *abfd,
 754          asection *section,
 755          PTR data,
 756          file_ptr offset,
 757          bfd_size_type count);
 758
 759
 760 DESCRIPTION
 761         Sets the contents of the section @var{section} in BFD
 762         @var{abfd} to the data starting in memory at @var{data}. The
 763         data is written to the output section starting at offset
 764         @var{offset} for @var{count} bytes.
 765
 766
 767
 768         Normally <<true>> is returned, else <<false>>. Possible error
 769         returns are:
 770         o no_contents -
 771         The output section does not have the <<SEC_HAS_CONTENTS>>
 772         attribute, so nothing can be written to it.
 773         o and some more too
 774
 775         This routine is front end to the back end function
 776         <<_bfd_set_section_contents>>.
 777
 778
 779 */
 780
 781 #define bfd_get_section_size_now(abfd,sec) \
 782 (sec->reloc_done \
 783  ? bfd_get_section_size_after_reloc (sec) \
 784  : bfd_get_section_size_before_reloc (sec))
 785
 786 boolean
 787 DEFUN(bfd_set_section_contents,(abfd, section, location, offset, count),
 788       bfd *abfd AND
 789       sec_ptr section AND
 790       PTR location AND
 791       file_ptr offset AND
 792       bfd_size_type count)
 793 {
 794   bfd_size_type sz;
 795
 796   if (!bfd_get_section_flags(abfd, section) & SEC_HAS_CONTENTS)
 797       {
 798         bfd_error = no_contents;
 799         return(false);
 800       }
 801
 802   if (offset < 0)
 803     {
 804     bad_val:
 805       bfd_error = bad_value;
 806       return false;
 807     }
 808   sz = bfd_get_section_size_now (abfd, section);
 809   if (offset > sz
 810       || count > sz
 811       || offset + count > sz)
 812     goto bad_val;
 813
 814   switch (abfd->direction)
 815     {
 816       case read_direction:
 817       case no_direction:
 818         bfd_error = invalid_operation;
 819         return false;
 820
 821       case write_direction:
 822         break;
 823
 824       case both_direction:
 825         /* File is opened for update. `output_has_begun' some time ago when
 826            the file was created.  Do not recompute sections sizes or alignments
 827            in _bfd_set_section_content.  */
 828         abfd->output_has_begun = true;
 829         break;
 830     }
 831
 832   if (BFD_SEND (abfd, _bfd_set_section_contents,
 833                 (abfd, section, location, offset, count)))
 834       {
 835         abfd->output_has_begun = true;
 836         return true;
 837       }
 838
 839   return false;
 840 }
 841
 842 /*
 843 FUNCTION
 844         bfd_get_section_contents
 845
 846 SYNOPSIS
 847         boolean bfd_get_section_contents
 848         (bfd *abfd, asection *section, PTR location,
 849          file_ptr offset, bfd_size_type count);
 850
 851 DESCRIPTION
 852         Read data from @var{section} in BFD @var{abfd}
 853         into memory starting at @var{location}. The data is read at an
 854         offset of @var{offset} from the start of the input section,
 855         and is read for @var{count} bytes.
 856
 857         If the contents of a constuctor with the <<SEC_CONSTUCTOR>>
 858         flag set are requested, then the @var{location} is filled with
 859         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   return BFD_SEND (abfd, _bfd_get_section_contents,
 898                    (abfd, section, location, offset, count));
 899 }