bfd/section.c

   1 /* Object file "section" support for the BFD library.
   2    Copyright (C) 1990, 91, 92, 93, 94, 95, 1996 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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 COFF shared library section.  This flag is
 233 .           only for the linker.  If this type of section appears in
 234 .           the input file, the linker must copy it to the output file
 235 .           without changing the vma or size.  FIXME: Although this
 236 .           was originally intended to be general, it really is COFF
 237 .           specific (and the flag was renamed to indicate this).  It
 238 .           might be cleaner to have some more general mechanism to
 239 .           allow the back end to control what the linker does with
 240 .           sections. *}
 241 .#define SEC_COFF_SHARED_LIBRARY 0x800
 242 .
 243 .        {* The section is a common section (symbols may be defined
 244 .           multiple times, the value of a symbol is the amount of
 245 .           space it requires, and the largest symbol value is the one
 246 .           used).  Most targets have exactly one of these (which we
 247 .           translate to bfd_com_section_ptr), but ECOFF has two. *}
 248 .#define SEC_IS_COMMON 0x8000
 249 .
 250 .        {* The section contains only debugging information.  For
 251 .           example, this is set for ELF .debug and .stab sections.
 252 .           strip tests this flag to see if a section can be
 253 .           discarded. *}
 254 .#define SEC_DEBUGGING 0x10000
 255 .
 256 .        {* The contents of this section are held in memory pointed to
 257 .           by the contents field.  This is checked by
 258 .           bfd_get_section_contents, and the data is retrieved from
 259 .           memory if appropriate.  *}
 260 .#define SEC_IN_MEMORY 0x20000
 261 .
 262 .        {* The contents of this section are to be excluded by the
 263 .           linker for executable and shared objects unless those
 264 .           objects are to be further relocated.  *}
 265 .#define SEC_EXCLUDE 0x40000
 266 .
 267 .       {* The contents of this section are to be sorted by the
 268 .          based on the address specified in the associated symbol
 269 .          table.  *}
 270 .#define SEC_SORT_ENTRIES 0x80000
 271 .
 272 .       {*  End of section flags.  *}
 273 .
 274 .       {* Some internal packed boolean fields.  *}
 275 .
 276 .       {* See the vma field.  *}
 277 .       unsigned int user_set_vma : 1;
 278 .
 279 .       {* Whether relocations have been processed.  *}
 280 .       unsigned int reloc_done : 1;
 281 .
 282 .       {* A mark flag used by some of the linker backends.  *}
 283 .       unsigned int linker_mark : 1;
 284 .
 285 .       {* End of internal packed boolean fields.  *}
 286 .
 287 .       {*  The virtual memory address of the section - where it will be
 288 .           at run time.  The symbols are relocated against this.  The
 289 .           user_set_vma flag is maintained by bfd; if it's not set, the
 290 .           backend can assign addresses (for example, in <<a.out>>, where
 291 .           the default address for <<.data>> is dependent on the specific
 292 .           target and various flags).  *}
 293 .
 294 .   bfd_vma vma;
 295 .
 296 .       {*  The load address of the section - where it would be in a
 297 .           rom image; really only used for writing section header
 298 .           information. *}
 299 .
 300 .   bfd_vma lma;
 301 .
 302 .        {* The size of the section in bytes, as it will be output.
 303 .           contains a value even if the section has no contents (e.g., the
 304 .           size of <<.bss>>). This will be filled in after relocation *}
 305 .
 306 .   bfd_size_type _cooked_size;
 307 .
 308 .        {* The original size on disk of the section, in bytes.  Normally this
 309 .           value is the same as the size, but if some relaxing has
 310 .           been done, then this value will be bigger.  *}
 311 .
 312 .   bfd_size_type _raw_size;
 313 .
 314 .        {* If this section is going to be output, then this value is the
 315 .           offset into the output section of the first byte in the input
 316 .           section. E.g., if this was going to start at the 100th byte in
 317 .           the output section, this value would be 100. *}
 318 .
 319 .   bfd_vma output_offset;
 320 .
 321 .        {* The output section through which to map on output. *}
 322 .
 323 .   struct sec *output_section;
 324 .
 325 .        {* The alignment requirement of the section, as an exponent of 2 -
 326 .           e.g., 3 aligns to 2^3 (or 8). *}
 327 .
 328 .   unsigned int alignment_power;
 329 .
 330 .        {* If an input section, a pointer to a vector of relocation
 331 .           records for the data in this section. *}
 332 .
 333 .   struct reloc_cache_entry *relocation;
 334 .
 335 .        {* If an output section, a pointer to a vector of pointers to
 336 .           relocation records for the data in this section. *}
 337 .
 338 .   struct reloc_cache_entry **orelocation;
 339 .
 340 .        {* The number of relocation records in one of the above  *}
 341 .
 342 .   unsigned reloc_count;
 343 .
 344 .        {* Information below is back end specific - and not always used
 345 .           or updated.  *}
 346 .
 347 .        {* File position of section data    *}
 348 .
 349 .   file_ptr filepos;
 350 .
 351 .        {* File position of relocation info *}
 352 .
 353 .   file_ptr rel_filepos;
 354 .
 355 .        {* File position of line data       *}
 356 .
 357 .   file_ptr line_filepos;
 358 .
 359 .        {* Pointer to data for applications *}
 360 .
 361 .   PTR userdata;
 362 .
 363 .        {* If the SEC_IN_MEMORY flag is set, this points to the actual
 364 .           contents.  *}
 365 .   unsigned char *contents;
 366 .
 367 .        {* Attached line number information *}
 368 .
 369 .   alent *lineno;
 370 .
 371 .        {* Number of line number records   *}
 372 .
 373 .   unsigned int lineno_count;
 374 .
 375 .        {* When a section is being output, this value changes as more
 376 .           linenumbers are written out *}
 377 .
 378 .   file_ptr moving_line_filepos;
 379 .
 380 .        {* What the section number is in the target world  *}
 381 .
 382 .   int target_index;
 383 .
 384 .   PTR used_by_bfd;
 385 .
 386 .        {* If this is a constructor section then here is a list of the
 387 .           relocations created to relocate items within it. *}
 388 .
 389 .   struct relent_chain *constructor_chain;
 390 .
 391 .        {* The BFD which owns the section. *}
 392 .
 393 .   bfd *owner;
 394 .
 395 .        {* A symbol which points at this section only *}
 396 .   struct symbol_cache_entry *symbol;
 397 .   struct symbol_cache_entry **symbol_ptr_ptr;
 398 .
 399 .   struct bfd_link_order *link_order_head;
 400 .   struct bfd_link_order *link_order_tail;
 401 .} asection ;
 402 .
 403 .    {* These sections are global, and are managed by BFD.  The application
 404 .       and target back end are not permitted to change the values in
 405 .       these sections.  New code should use the section_ptr macros rather
 406 .       than referring directly to the const sections.  The const sections
 407 .       may eventually vanish.  *}
 408 .#define BFD_ABS_SECTION_NAME "*ABS*"
 409 .#define BFD_UND_SECTION_NAME "*UND*"
 410 .#define BFD_COM_SECTION_NAME "*COM*"
 411 .#define BFD_IND_SECTION_NAME "*IND*"
 412 .
 413 .    {* the absolute section *}
 414 .extern const asection bfd_abs_section;
 415 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
 416 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
 417 .    {* Pointer to the undefined section *}
 418 .extern const asection bfd_und_section;
 419 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
 420 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
 421 .    {* Pointer to the common section *}
 422 .extern const asection bfd_com_section;
 423 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
 424 .    {* Pointer to the indirect section *}
 425 .extern const asection bfd_ind_section;
 426 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
 427 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
 428 .
 429 .extern const struct symbol_cache_entry * const bfd_abs_symbol;
 430 .extern const struct symbol_cache_entry * const bfd_com_symbol;
 431 .extern const struct symbol_cache_entry * const bfd_und_symbol;
 432 .extern const struct symbol_cache_entry * const bfd_ind_symbol;
 433 .#define bfd_get_section_size_before_reloc(section) \
 434 .     (section->reloc_done ? (abort(),1): (section)->_raw_size)
 435 .#define bfd_get_section_size_after_reloc(section) \
 436 .     ((section->reloc_done) ? (section)->_cooked_size: (abort(),1))
 437 */
 438
 439 /* These symbols are global, not specific to any BFD.  Therefore, anything
 440    that tries to change them is broken, and should be repaired.  */
 441 static const asymbol global_syms[] =
 442 {
 443  /* the_bfd, name, value, attr, section [, udata] */
 444   {0, BFD_COM_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_com_section},
 445   {0, BFD_UND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_und_section},
 446   {0, BFD_ABS_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_abs_section},
 447   {0, BFD_IND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_ind_section},
 448 };
 449
 450 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
 451   const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
 452   const asection SEC = \
 453     { NAME, 0, 0, FLAGS, 0, 0, 0, 0, 0, 0, 0, 0, (asection *) &SEC, \
 454       0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0, \
 455       (asymbol *) &global_syms[IDX], (asymbol **) &SYM, 0, 0 }
 456
 457 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
 458              BFD_COM_SECTION_NAME, 0);
 459 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
 460 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
 461 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
 462 #undef STD_SECTION
 463
 464 /*
 465 DOCDD
 466 INODE
 467 section prototypes,  , typedef asection, Sections
 468 SUBSECTION
 469         Section prototypes
 470
 471 These are the functions exported by the section handling part of BFD.
 472 */
 473
 474 /*
 475 FUNCTION
 476         bfd_get_section_by_name
 477
 478 SYNOPSIS
 479         asection *bfd_get_section_by_name(bfd *abfd, CONST char *name);
 480
 481 DESCRIPTION
 482         Run through @var{abfd} and return the one of the
 483         <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
 484         @xref{Sections}, for more information.
 485
 486         This should only be used in special cases; the normal way to process
 487         all sections of a given name is to use <<bfd_map_over_sections>> and
 488         <<strcmp>> on the name (or better yet, base it on the section flags
 489         or something else) for each section.
 490 */
 491
 492 asection *
 493 bfd_get_section_by_name (abfd, name)
 494      bfd *abfd;
 495      CONST char *name;
 496 {
 497   asection *sect;
 498
 499   for (sect = abfd->sections; sect != NULL; sect = sect->next)
 500     if (!strcmp (sect->name, name))
 501       return sect;
 502   return NULL;
 503 }
 504
 505
 506 /*
 507 FUNCTION
 508         bfd_make_section_old_way
 509
 510 SYNOPSIS
 511         asection *bfd_make_section_old_way(bfd *abfd, CONST char *name);
 512
 513 DESCRIPTION
 514         Create a new empty section called @var{name}
 515         and attach it to the end of the chain of sections for the
 516         BFD @var{abfd}. An attempt to create a section with a name which
 517         is already in use returns its pointer without changing the
 518         section chain.
 519
 520         It has the funny name since this is the way it used to be
 521         before it was rewritten....
 522
 523         Possible errors are:
 524         o <<bfd_error_invalid_operation>> -
 525         If output has already started for this BFD.
 526         o <<bfd_error_no_memory>> -
 527         If obstack alloc fails.
 528
 529 */
 530
 531
 532 asection *
 533 bfd_make_section_old_way (abfd, name)
 534      bfd *abfd;
 535      CONST char *name;
 536 {
 537   asection *sec = bfd_get_section_by_name (abfd, name);
 538   if (sec == (asection *) NULL)
 539     {
 540       sec = bfd_make_section (abfd, name);
 541     }
 542   return sec;
 543 }
 544
 545 /*
 546 FUNCTION
 547         bfd_make_section_anyway
 548
 549 SYNOPSIS
 550         asection *bfd_make_section_anyway(bfd *abfd, CONST char *name);
 551
 552 DESCRIPTION
 553    Create a new empty section called @var{name} and attach it to the end of
 554    the chain of sections for @var{abfd}.  Create a new section even if there
 555    is already a section with that name.
 556
 557    Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
 558    o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
 559    o <<bfd_error_no_memory>> - If obstack alloc fails.
 560 */
 561
 562 sec_ptr
 563 bfd_make_section_anyway (abfd, name)
 564      bfd *abfd;
 565      CONST char *name;
 566 {
 567   asection *newsect;
 568   asection **prev = &abfd->sections;
 569   asection *sect = abfd->sections;
 570
 571   if (abfd->output_has_begun)
 572     {
 573       bfd_set_error (bfd_error_invalid_operation);
 574       return NULL;
 575     }
 576
 577   while (sect)
 578     {
 579       prev = &sect->next;
 580       sect = sect->next;
 581     }
 582
 583   newsect = (asection *) bfd_zalloc (abfd, sizeof (asection));
 584   if (newsect == NULL)
 585     return NULL;
 586
 587   newsect->name = name;
 588   newsect->index = abfd->section_count++;
 589   newsect->flags = SEC_NO_FLAGS;
 590
 591   newsect->userdata = NULL;
 592   newsect->contents = NULL;
 593   newsect->next = (asection *) NULL;
 594   newsect->relocation = (arelent *) NULL;
 595   newsect->reloc_count = 0;
 596   newsect->line_filepos = 0;
 597   newsect->owner = abfd;
 598
 599   /* Create a symbol whos only job is to point to this section. This is
 600      useful for things like relocs which are relative to the base of a
 601      section.  */
 602   newsect->symbol = bfd_make_empty_symbol (abfd);
 603   if (newsect->symbol == NULL)
 604     return NULL;
 605   newsect->symbol->name = name;
 606   newsect->symbol->value = 0;
 607   newsect->symbol->section = newsect;
 608   newsect->symbol->flags = BSF_SECTION_SYM;
 609
 610   newsect->symbol_ptr_ptr = &newsect->symbol;
 611
 612   if (BFD_SEND (abfd, _new_section_hook, (abfd, newsect)) != true)
 613     {
 614       free (newsect);
 615       return NULL;
 616     }
 617
 618   *prev = newsect;
 619   return newsect;
 620 }
 621
 622 /*
 623 FUNCTION
 624         bfd_make_section
 625
 626 SYNOPSIS
 627         asection *bfd_make_section(bfd *, CONST char *name);
 628
 629 DESCRIPTION
 630    Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
 631    bfd_set_error ()) without changing the section chain if there is already a
 632    section named @var{name}.  If there is an error, return <<NULL>> and set
 633    <<bfd_error>>.
 634 */
 635
 636 asection *
 637 bfd_make_section (abfd, name)
 638      bfd *abfd;
 639      CONST char *name;
 640 {
 641   asection *sect = abfd->sections;
 642
 643   if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
 644     {
 645       return bfd_abs_section_ptr;
 646     }
 647   if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
 648     {
 649       return bfd_com_section_ptr;
 650     }
 651   if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
 652     {
 653       return bfd_und_section_ptr;
 654     }
 655
 656   if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
 657     {
 658       return bfd_ind_section_ptr;
 659     }
 660
 661   while (sect)
 662     {
 663       if (!strcmp (sect->name, name))
 664         return NULL;
 665       sect = sect->next;
 666     }
 667
 668   /* The name is not already used; go ahead and make a new section.  */
 669   return bfd_make_section_anyway (abfd, name);
 670 }
 671
 672
 673 /*
 674 FUNCTION
 675         bfd_set_section_flags
 676
 677 SYNOPSIS
 678         boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags);
 679
 680 DESCRIPTION
 681         Set the attributes of the section @var{sec} in the BFD
 682         @var{abfd} to the value @var{flags}. Return <<true>> on success,
 683         <<false>> on error. Possible error returns are:
 684
 685         o <<bfd_error_invalid_operation>> -
 686         The section cannot have one or more of the attributes
 687         requested. For example, a .bss section in <<a.out>> may not
 688         have the <<SEC_HAS_CONTENTS>> field set.
 689
 690 */
 691
 692 /*ARGSUSED*/
 693 boolean
 694 bfd_set_section_flags (abfd, section, flags)
 695      bfd *abfd;
 696      sec_ptr section;
 697      flagword flags;
 698 {
 699 #if 0
 700   /* If you try to copy a text section from an input file (where it
 701      has the SEC_CODE flag set) to an output file, this loses big if
 702      the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
 703      set - which it doesn't, at least not for a.out.  FIXME */
 704
 705   if ((flags & bfd_applicable_section_flags (abfd)) != flags)
 706     {
 707       bfd_set_error (bfd_error_invalid_operation);
 708       return false;
 709     }
 710 #endif
 711
 712   section->flags = flags;
 713   return true;
 714 }
 715
 716
 717 /*
 718 FUNCTION
 719         bfd_map_over_sections
 720
 721 SYNOPSIS
 722         void bfd_map_over_sections(bfd *abfd,
 723                                    void (*func)(bfd *abfd,
 724                                                 asection *sect,
 725                                                 PTR obj),
 726                                    PTR obj);
 727
 728 DESCRIPTION
 729         Call the provided function @var{func} for each section
 730         attached to the BFD @var{abfd}, passing @var{obj} as an
 731         argument. The function will be called as if by
 732
 733 |       func(abfd, the_section, obj);
 734
 735         This is the prefered method for iterating over sections; an
 736         alternative would be to use a loop:
 737
 738 |          section *p;
 739 |          for (p = abfd->sections; p != NULL; p = p->next)
 740 |             func(abfd, p, ...)
 741
 742
 743 */
 744
 745 /*VARARGS2*/
 746 void
 747 bfd_map_over_sections (abfd, operation, user_storage)
 748      bfd *abfd;
 749      void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj));
 750      PTR user_storage;
 751 {
 752   asection *sect;
 753   unsigned int i = 0;
 754
 755   for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
 756     (*operation) (abfd, sect, user_storage);
 757
 758   if (i != abfd->section_count) /* Debugging */
 759     abort ();
 760 }
 761
 762
 763 /*
 764 FUNCTION
 765         bfd_set_section_size
 766
 767 SYNOPSIS
 768         boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val);
 769
 770 DESCRIPTION
 771         Set @var{sec} to the size @var{val}. If the operation is
 772         ok, then <<true>> is returned, else <<false>>.
 773
 774         Possible error returns:
 775         o <<bfd_error_invalid_operation>> -
 776         Writing has started to the BFD, so setting the size is invalid.
 777
 778 */
 779
 780 boolean
 781 bfd_set_section_size (abfd, ptr, val)
 782      bfd *abfd;
 783      sec_ptr ptr;
 784      bfd_size_type val;
 785 {
 786   /* Once you've started writing to any section you cannot create or change
 787      the size of any others. */
 788
 789   if (abfd->output_has_begun)
 790     {
 791       bfd_set_error (bfd_error_invalid_operation);
 792       return false;
 793     }
 794
 795   ptr->_cooked_size = val;
 796   ptr->_raw_size = val;
 797
 798   return true;
 799 }
 800
 801 /*
 802 FUNCTION
 803         bfd_set_section_contents
 804
 805 SYNOPSIS
 806         boolean bfd_set_section_contents
 807          (bfd *abfd,
 808          asection *section,
 809          PTR data,
 810          file_ptr offset,
 811          bfd_size_type count);
 812
 813
 814 DESCRIPTION
 815         Sets the contents of the section @var{section} in BFD
 816         @var{abfd} to the data starting in memory at @var{data}. The
 817         data is written to the output section starting at offset
 818         @var{offset} for @var{count} bytes.
 819
 820
 821
 822         Normally <<true>> is returned, else <<false>>. Possible error
 823         returns are:
 824         o <<bfd_error_no_contents>> -
 825         The output section does not have the <<SEC_HAS_CONTENTS>>
 826         attribute, so nothing can be written to it.
 827         o and some more too
 828
 829         This routine is front end to the back end function
 830         <<_bfd_set_section_contents>>.
 831
 832
 833 */
 834
 835 #define bfd_get_section_size_now(abfd,sec) \
 836 (sec->reloc_done \
 837  ? bfd_get_section_size_after_reloc (sec) \
 838  : bfd_get_section_size_before_reloc (sec))
 839
 840 boolean
 841 bfd_set_section_contents (abfd, section, location, offset, count)
 842      bfd *abfd;
 843      sec_ptr section;
 844      PTR location;
 845      file_ptr offset;
 846      bfd_size_type count;
 847 {
 848   bfd_size_type sz;
 849
 850   if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
 851     {
 852       bfd_set_error (bfd_error_no_contents);
 853       return (false);
 854     }
 855
 856   if (offset < 0)
 857     {
 858     bad_val:
 859       bfd_set_error (bfd_error_bad_value);
 860       return false;
 861     }
 862   sz = bfd_get_section_size_now (abfd, section);
 863   if ((bfd_size_type) offset > sz
 864       || count > sz
 865       || offset + count > sz)
 866     goto bad_val;
 867
 868   switch (abfd->direction)
 869     {
 870     case read_direction:
 871     case no_direction:
 872       bfd_set_error (bfd_error_invalid_operation);
 873       return false;
 874
 875     case write_direction:
 876       break;
 877
 878     case both_direction:
 879       /* File is opened for update. `output_has_begun' some time ago when
 880            the file was created.  Do not recompute sections sizes or alignments
 881            in _bfd_set_section_content.  */
 882       abfd->output_has_begun = true;
 883       break;
 884     }
 885
 886   if (BFD_SEND (abfd, _bfd_set_section_contents,
 887                 (abfd, section, location, offset, count)))
 888     {
 889       abfd->output_has_begun = true;
 890       return true;
 891     }
 892
 893   return false;
 894 }
 895
 896 /*
 897 FUNCTION
 898         bfd_get_section_contents
 899
 900 SYNOPSIS
 901         boolean bfd_get_section_contents
 902         (bfd *abfd, asection *section, PTR location,
 903          file_ptr offset, bfd_size_type count);
 904
 905 DESCRIPTION
 906         Read data from @var{section} in BFD @var{abfd}
 907         into memory starting at @var{location}. The data is read at an
 908         offset of @var{offset} from the start of the input section,
 909         and is read for @var{count} bytes.
 910
 911         If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
 912         flag set are requested or if the section does not have the
 913         <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
 914         with zeroes. If no errors occur, <<true>> is returned, else
 915         <<false>>.
 916
 917
 918
 919 */
 920 boolean
 921 bfd_get_section_contents (abfd, section, location, offset, count)
 922      bfd *abfd;
 923      sec_ptr section;
 924      PTR location;
 925      file_ptr offset;
 926      bfd_size_type count;
 927 {
 928   bfd_size_type sz;
 929
 930   if (section->flags & SEC_CONSTRUCTOR)
 931     {
 932       memset (location, 0, (unsigned) count);
 933       return true;
 934     }
 935
 936   if (offset < 0)
 937     {
 938     bad_val:
 939       bfd_set_error (bfd_error_bad_value);
 940       return false;
 941     }
 942   /* Even if reloc_done is true, this function reads unrelocated
 943      contents, so we want the raw size.  */
 944   sz = section->_raw_size;
 945   if ((bfd_size_type) offset > sz || count > sz || offset + count > sz)
 946     goto bad_val;
 947
 948   if (count == 0)
 949     /* Don't bother.  */
 950     return true;
 951
 952   if ((section->flags & SEC_HAS_CONTENTS) == 0)
 953     {
 954       memset (location, 0, (unsigned) count);
 955       return true;
 956     }
 957
 958   if ((section->flags & SEC_IN_MEMORY) != 0)
 959     {
 960       memcpy (location, section->contents + offset, (size_t) count);
 961       return true;
 962     }
 963
 964   return BFD_SEND (abfd, _bfd_get_section_contents,
 965                    (abfd, section, location, offset, count));
 966 }
 967
 968 /*
 969 FUNCTION
 970         bfd_copy_private_section_data
 971
 972 SYNOPSIS
 973         boolean bfd_copy_private_section_data(bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
 974
 975 DESCRIPTION
 976         Copy private section information from @var{isec} in the BFD
 977         @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
 978         Return <<true>> on success, <<false>> on error.  Possible error
 979         returns are:
 980
 981         o <<bfd_error_no_memory>> -
 982         Not enough memory exists to create private data for @var{osec}.
 983
 984 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
 985 .     BFD_SEND (ibfd, _bfd_copy_private_section_data, \
 986 .               (ibfd, isection, obfd, osection))
 987 */