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 contains common symbols (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 .       {* When linking, duplicate sections of the same name should be
 273 .          discarded, rather than being combined into a single section as
 274 .          is usually done.  This is similar to how common symbols are
 275 .          handled.  See SEC_LINK_DUPLICATES below.  *}
 276 .#define SEC_LINK_ONCE 0x100000
 277 .
 278 .       {* If SEC_LINK_ONCE is set, this bitfield describes how the linker
 279 .          should handle duplicate sections.  *}
 280 .#define SEC_LINK_DUPLICATES 0x600000
 281 .
 282 .       {* This value for SEC_LINK_DUPLICATES means that duplicate
 283 .          sections with the same name should simply be discarded. *}
 284 .#define SEC_LINK_DUPLICATES_DISCARD 0x0
 285 .
 286 .       {* This value for SEC_LINK_DUPLICATES means that the linker
 287 .          should warn if there are any duplicate sections, although
 288 .          it should still only link one copy.  *}
 289 .#define SEC_LINK_DUPLICATES_ONE_ONLY 0x200000
 290 .
 291 .       {* This value for SEC_LINK_DUPLICATES means that the linker
 292 .          should warn if any duplicate sections are a different size.  *}
 293 .#define SEC_LINK_DUPLICATES_SAME_SIZE 0x400000
 294 .
 295 .       {* This value for SEC_LINK_DUPLICATES means that the linker
 296 .          should warn if any duplicate sections contain different
 297 .          contents.  *}
 298 .#define SEC_LINK_DUPLICATES_SAME_CONTENTS 0x600000
 299 .
 300 .       {* This section was created by the linker as part of dynamic
 301 .          relocation or other arcane processing.  It is skipped when
 302 .          going through the first-pass output, trusting that someone
 303 .          else up the line will take care of it later.  *}
 304 .#define SEC_LINKER_CREATED 0x800000
 305 .
 306 .       {*  End of section flags.  *}
 307 .
 308 .       {* Some internal packed boolean fields.  *}
 309 .
 310 .       {* See the vma field.  *}
 311 .       unsigned int user_set_vma : 1;
 312 .
 313 .       {* Whether relocations have been processed.  *}
 314 .       unsigned int reloc_done : 1;
 315 .
 316 .       {* A mark flag used by some of the linker backends.  *}
 317 .       unsigned int linker_mark : 1;
 318 .
 319 .       {* End of internal packed boolean fields.  *}
 320 .
 321 .       {*  The virtual memory address of the section - where it will be
 322 .           at run time.  The symbols are relocated against this.  The
 323 .           user_set_vma flag is maintained by bfd; if it's not set, the
 324 .           backend can assign addresses (for example, in <<a.out>>, where
 325 .           the default address for <<.data>> is dependent on the specific
 326 .           target and various flags).  *}
 327 .
 328 .   bfd_vma vma;
 329 .
 330 .       {*  The load address of the section - where it would be in a
 331 .           rom image; really only used for writing section header
 332 .           information. *}
 333 .
 334 .   bfd_vma lma;
 335 .
 336 .        {* The size of the section in bytes, as it will be output.
 337 .           contains a value even if the section has no contents (e.g., the
 338 .           size of <<.bss>>). This will be filled in after relocation *}
 339 .
 340 .   bfd_size_type _cooked_size;
 341 .
 342 .        {* The original size on disk of the section, in bytes.  Normally this
 343 .           value is the same as the size, but if some relaxing has
 344 .           been done, then this value will be bigger.  *}
 345 .
 346 .   bfd_size_type _raw_size;
 347 .
 348 .        {* If this section is going to be output, then this value is the
 349 .           offset into the output section of the first byte in the input
 350 .           section. E.g., if this was going to start at the 100th byte in
 351 .           the output section, this value would be 100. *}
 352 .
 353 .   bfd_vma output_offset;
 354 .
 355 .        {* The output section through which to map on output. *}
 356 .
 357 .   struct sec *output_section;
 358 .
 359 .        {* The alignment requirement of the section, as an exponent of 2 -
 360 .           e.g., 3 aligns to 2^3 (or 8). *}
 361 .
 362 .   unsigned int alignment_power;
 363 .
 364 .        {* If an input section, a pointer to a vector of relocation
 365 .           records for the data in this section. *}
 366 .
 367 .   struct reloc_cache_entry *relocation;
 368 .
 369 .        {* If an output section, a pointer to a vector of pointers to
 370 .           relocation records for the data in this section. *}
 371 .
 372 .   struct reloc_cache_entry **orelocation;
 373 .
 374 .        {* The number of relocation records in one of the above  *}
 375 .
 376 .   unsigned reloc_count;
 377 .
 378 .        {* Information below is back end specific - and not always used
 379 .           or updated.  *}
 380 .
 381 .        {* File position of section data    *}
 382 .
 383 .   file_ptr filepos;
 384 .
 385 .        {* File position of relocation info *}
 386 .
 387 .   file_ptr rel_filepos;
 388 .
 389 .        {* File position of line data       *}
 390 .
 391 .   file_ptr line_filepos;
 392 .
 393 .        {* Pointer to data for applications *}
 394 .
 395 .   PTR userdata;
 396 .
 397 .        {* If the SEC_IN_MEMORY flag is set, this points to the actual
 398 .           contents.  *}
 399 .   unsigned char *contents;
 400 .
 401 .        {* Attached line number information *}
 402 .
 403 .   alent *lineno;
 404 .
 405 .        {* Number of line number records   *}
 406 .
 407 .   unsigned int lineno_count;
 408 .
 409 .        {* When a section is being output, this value changes as more
 410 .           linenumbers are written out *}
 411 .
 412 .   file_ptr moving_line_filepos;
 413 .
 414 .        {* What the section number is in the target world  *}
 415 .
 416 .   int target_index;
 417 .
 418 .   PTR used_by_bfd;
 419 .
 420 .        {* If this is a constructor section then here is a list of the
 421 .           relocations created to relocate items within it. *}
 422 .
 423 .   struct relent_chain *constructor_chain;
 424 .
 425 .        {* The BFD which owns the section. *}
 426 .
 427 .   bfd *owner;
 428 .
 429 .        {* A symbol which points at this section only *}
 430 .   struct symbol_cache_entry *symbol;
 431 .   struct symbol_cache_entry **symbol_ptr_ptr;
 432 .
 433 .   struct bfd_link_order *link_order_head;
 434 .   struct bfd_link_order *link_order_tail;
 435 .} asection ;
 436 .
 437 .    {* These sections are global, and are managed by BFD.  The application
 438 .       and target back end are not permitted to change the values in
 439 .       these sections.  New code should use the section_ptr macros rather
 440 .       than referring directly to the const sections.  The const sections
 441 .       may eventually vanish.  *}
 442 .#define BFD_ABS_SECTION_NAME "*ABS*"
 443 .#define BFD_UND_SECTION_NAME "*UND*"
 444 .#define BFD_COM_SECTION_NAME "*COM*"
 445 .#define BFD_IND_SECTION_NAME "*IND*"
 446 .
 447 .    {* the absolute section *}
 448 .extern const asection bfd_abs_section;
 449 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
 450 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
 451 .    {* Pointer to the undefined section *}
 452 .extern const asection bfd_und_section;
 453 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
 454 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
 455 .    {* Pointer to the common section *}
 456 .extern const asection bfd_com_section;
 457 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
 458 .    {* Pointer to the indirect section *}
 459 .extern const asection bfd_ind_section;
 460 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
 461 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
 462 .
 463 .extern const struct symbol_cache_entry * const bfd_abs_symbol;
 464 .extern const struct symbol_cache_entry * const bfd_com_symbol;
 465 .extern const struct symbol_cache_entry * const bfd_und_symbol;
 466 .extern const struct symbol_cache_entry * const bfd_ind_symbol;
 467 .#define bfd_get_section_size_before_reloc(section) \
 468 .     (section->reloc_done ? (abort(),1): (section)->_raw_size)
 469 .#define bfd_get_section_size_after_reloc(section) \
 470 .     ((section->reloc_done) ? (section)->_cooked_size: (abort(),1))
 471 */
 472
 473 /* These symbols are global, not specific to any BFD.  Therefore, anything
 474    that tries to change them is broken, and should be repaired.  */
 475 static const asymbol global_syms[] =
 476 {
 477  /* the_bfd, name, value, attr, section [, udata] */
 478   {0, BFD_COM_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_com_section},
 479   {0, BFD_UND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_und_section},
 480   {0, BFD_ABS_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_abs_section},
 481   {0, BFD_IND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_ind_section},
 482 };
 483
 484 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
 485   const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
 486   const asection SEC = \
 487     { NAME, 0, 0, FLAGS, 0, 0, 0, 0, 0, 0, 0, 0, (asection *) &SEC, \
 488       0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0, \
 489       (asymbol *) &global_syms[IDX], (asymbol **) &SYM, 0, 0 }
 490
 491 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
 492              BFD_COM_SECTION_NAME, 0);
 493 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
 494 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
 495 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
 496 #undef STD_SECTION
 497
 498 /*
 499 DOCDD
 500 INODE
 501 section prototypes,  , typedef asection, Sections
 502 SUBSECTION
 503         Section prototypes
 504
 505 These are the functions exported by the section handling part of BFD.
 506 */
 507
 508 /*
 509 FUNCTION
 510         bfd_get_section_by_name
 511
 512 SYNOPSIS
 513         asection *bfd_get_section_by_name(bfd *abfd, CONST char *name);
 514
 515 DESCRIPTION
 516         Run through @var{abfd} and return the one of the
 517         <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
 518         @xref{Sections}, for more information.
 519
 520         This should only be used in special cases; the normal way to process
 521         all sections of a given name is to use <<bfd_map_over_sections>> and
 522         <<strcmp>> on the name (or better yet, base it on the section flags
 523         or something else) for each section.
 524 */
 525
 526 asection *
 527 bfd_get_section_by_name (abfd, name)
 528      bfd *abfd;
 529      CONST char *name;
 530 {
 531   asection *sect;
 532
 533   for (sect = abfd->sections; sect != NULL; sect = sect->next)
 534     if (!strcmp (sect->name, name))
 535       return sect;
 536   return NULL;
 537 }
 538
 539
 540 /*
 541 FUNCTION
 542         bfd_make_section_old_way
 543
 544 SYNOPSIS
 545         asection *bfd_make_section_old_way(bfd *abfd, CONST char *name);
 546
 547 DESCRIPTION
 548         Create a new empty section called @var{name}
 549         and attach it to the end of the chain of sections for the
 550         BFD @var{abfd}. An attempt to create a section with a name which
 551         is already in use returns its pointer without changing the
 552         section chain.
 553
 554         It has the funny name since this is the way it used to be
 555         before it was rewritten....
 556
 557         Possible errors are:
 558         o <<bfd_error_invalid_operation>> -
 559         If output has already started for this BFD.
 560         o <<bfd_error_no_memory>> -
 561         If obstack alloc fails.
 562
 563 */
 564
 565
 566 asection *
 567 bfd_make_section_old_way (abfd, name)
 568      bfd *abfd;
 569      CONST char *name;
 570 {
 571   asection *sec = bfd_get_section_by_name (abfd, name);
 572   if (sec == (asection *) NULL)
 573     {
 574       sec = bfd_make_section (abfd, name);
 575     }
 576   return sec;
 577 }
 578
 579 /*
 580 FUNCTION
 581         bfd_make_section_anyway
 582
 583 SYNOPSIS
 584         asection *bfd_make_section_anyway(bfd *abfd, CONST char *name);
 585
 586 DESCRIPTION
 587    Create a new empty section called @var{name} and attach it to the end of
 588    the chain of sections for @var{abfd}.  Create a new section even if there
 589    is already a section with that name.
 590
 591    Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
 592    o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
 593    o <<bfd_error_no_memory>> - If obstack alloc fails.
 594 */
 595
 596 sec_ptr
 597 bfd_make_section_anyway (abfd, name)
 598      bfd *abfd;
 599      CONST char *name;
 600 {
 601   asection *newsect;
 602   asection **prev = &abfd->sections;
 603   asection *sect = abfd->sections;
 604
 605   if (abfd->output_has_begun)
 606     {
 607       bfd_set_error (bfd_error_invalid_operation);
 608       return NULL;
 609     }
 610
 611   while (sect)
 612     {
 613       prev = &sect->next;
 614       sect = sect->next;
 615     }
 616
 617   newsect = (asection *) bfd_zalloc (abfd, sizeof (asection));
 618   if (newsect == NULL)
 619     return NULL;
 620
 621   newsect->name = name;
 622   newsect->index = abfd->section_count++;
 623   newsect->flags = SEC_NO_FLAGS;
 624
 625   newsect->userdata = NULL;
 626   newsect->contents = NULL;
 627   newsect->next = (asection *) NULL;
 628   newsect->relocation = (arelent *) NULL;
 629   newsect->reloc_count = 0;
 630   newsect->line_filepos = 0;
 631   newsect->owner = abfd;
 632
 633   /* Create a symbol whos only job is to point to this section. This is
 634      useful for things like relocs which are relative to the base of a
 635      section.  */
 636   newsect->symbol = bfd_make_empty_symbol (abfd);
 637   if (newsect->symbol == NULL)
 638     return NULL;
 639   newsect->symbol->name = name;
 640   newsect->symbol->value = 0;
 641   newsect->symbol->section = newsect;
 642   newsect->symbol->flags = BSF_SECTION_SYM;
 643
 644   newsect->symbol_ptr_ptr = &newsect->symbol;
 645
 646   if (BFD_SEND (abfd, _new_section_hook, (abfd, newsect)) != true)
 647     {
 648       free (newsect);
 649       return NULL;
 650     }
 651
 652   *prev = newsect;
 653   return newsect;
 654 }
 655
 656 /*
 657 FUNCTION
 658         bfd_make_section
 659
 660 SYNOPSIS
 661         asection *bfd_make_section(bfd *, CONST char *name);
 662
 663 DESCRIPTION
 664    Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
 665    bfd_set_error ()) without changing the section chain if there is already a
 666    section named @var{name}.  If there is an error, return <<NULL>> and set
 667    <<bfd_error>>.
 668 */
 669
 670 asection *
 671 bfd_make_section (abfd, name)
 672      bfd *abfd;
 673      CONST char *name;
 674 {
 675   asection *sect = abfd->sections;
 676
 677   if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
 678     {
 679       return bfd_abs_section_ptr;
 680     }
 681   if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
 682     {
 683       return bfd_com_section_ptr;
 684     }
 685   if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
 686     {
 687       return bfd_und_section_ptr;
 688     }
 689
 690   if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
 691     {
 692       return bfd_ind_section_ptr;
 693     }
 694
 695   while (sect)
 696     {
 697       if (!strcmp (sect->name, name))
 698         return NULL;
 699       sect = sect->next;
 700     }
 701
 702   /* The name is not already used; go ahead and make a new section.  */
 703   return bfd_make_section_anyway (abfd, name);
 704 }
 705
 706
 707 /*
 708 FUNCTION
 709         bfd_set_section_flags
 710
 711 SYNOPSIS
 712         boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags);
 713
 714 DESCRIPTION
 715         Set the attributes of the section @var{sec} in the BFD
 716         @var{abfd} to the value @var{flags}. Return <<true>> on success,
 717         <<false>> on error. Possible error returns are:
 718
 719         o <<bfd_error_invalid_operation>> -
 720         The section cannot have one or more of the attributes
 721         requested. For example, a .bss section in <<a.out>> may not
 722         have the <<SEC_HAS_CONTENTS>> field set.
 723
 724 */
 725
 726 /*ARGSUSED*/
 727 boolean
 728 bfd_set_section_flags (abfd, section, flags)
 729      bfd *abfd;
 730      sec_ptr section;
 731      flagword flags;
 732 {
 733 #if 0
 734   /* If you try to copy a text section from an input file (where it
 735      has the SEC_CODE flag set) to an output file, this loses big if
 736      the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
 737      set - which it doesn't, at least not for a.out.  FIXME */
 738
 739   if ((flags & bfd_applicable_section_flags (abfd)) != flags)
 740     {
 741       bfd_set_error (bfd_error_invalid_operation);
 742       return false;
 743     }
 744 #endif
 745
 746   section->flags = flags;
 747   return true;
 748 }
 749
 750
 751 /*
 752 FUNCTION
 753         bfd_map_over_sections
 754
 755 SYNOPSIS
 756         void bfd_map_over_sections(bfd *abfd,
 757                                    void (*func)(bfd *abfd,
 758                                                 asection *sect,
 759                                                 PTR obj),
 760                                    PTR obj);
 761
 762 DESCRIPTION
 763         Call the provided function @var{func} for each section
 764         attached to the BFD @var{abfd}, passing @var{obj} as an
 765         argument. The function will be called as if by
 766
 767 |       func(abfd, the_section, obj);
 768
 769         This is the prefered method for iterating over sections; an
 770         alternative would be to use a loop:
 771
 772 |          section *p;
 773 |          for (p = abfd->sections; p != NULL; p = p->next)
 774 |             func(abfd, p, ...)
 775
 776
 777 */
 778
 779 /*VARARGS2*/
 780 void
 781 bfd_map_over_sections (abfd, operation, user_storage)
 782      bfd *abfd;
 783      void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj));
 784      PTR user_storage;
 785 {
 786   asection *sect;
 787   unsigned int i = 0;
 788
 789   for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
 790     (*operation) (abfd, sect, user_storage);
 791
 792   if (i != abfd->section_count) /* Debugging */
 793     abort ();
 794 }
 795
 796
 797 /*
 798 FUNCTION
 799         bfd_set_section_size
 800
 801 SYNOPSIS
 802         boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val);
 803
 804 DESCRIPTION
 805         Set @var{sec} to the size @var{val}. If the operation is
 806         ok, then <<true>> is returned, else <<false>>.
 807
 808         Possible error returns:
 809         o <<bfd_error_invalid_operation>> -
 810         Writing has started to the BFD, so setting the size is invalid.
 811
 812 */
 813
 814 boolean
 815 bfd_set_section_size (abfd, ptr, val)
 816      bfd *abfd;
 817      sec_ptr ptr;
 818      bfd_size_type val;
 819 {
 820   /* Once you've started writing to any section you cannot create or change
 821      the size of any others. */
 822
 823   if (abfd->output_has_begun)
 824     {
 825       bfd_set_error (bfd_error_invalid_operation);
 826       return false;
 827     }
 828
 829   ptr->_cooked_size = val;
 830   ptr->_raw_size = val;
 831
 832   return true;
 833 }
 834
 835 /*
 836 FUNCTION
 837         bfd_set_section_contents
 838
 839 SYNOPSIS
 840         boolean bfd_set_section_contents
 841          (bfd *abfd,
 842          asection *section,
 843          PTR data,
 844          file_ptr offset,
 845          bfd_size_type count);
 846
 847
 848 DESCRIPTION
 849         Sets the contents of the section @var{section} in BFD
 850         @var{abfd} to the data starting in memory at @var{data}. The
 851         data is written to the output section starting at offset
 852         @var{offset} for @var{count} bytes.
 853
 854
 855
 856         Normally <<true>> is returned, else <<false>>. Possible error
 857         returns are:
 858         o <<bfd_error_no_contents>> -
 859         The output section does not have the <<SEC_HAS_CONTENTS>>
 860         attribute, so nothing can be written to it.
 861         o and some more too
 862
 863         This routine is front end to the back end function
 864         <<_bfd_set_section_contents>>.
 865
 866
 867 */
 868
 869 #define bfd_get_section_size_now(abfd,sec) \
 870 (sec->reloc_done \
 871  ? bfd_get_section_size_after_reloc (sec) \
 872  : bfd_get_section_size_before_reloc (sec))
 873
 874 boolean
 875 bfd_set_section_contents (abfd, section, location, offset, count)
 876      bfd *abfd;
 877      sec_ptr section;
 878      PTR location;
 879      file_ptr offset;
 880      bfd_size_type count;
 881 {
 882   bfd_size_type sz;
 883
 884   if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
 885     {
 886       bfd_set_error (bfd_error_no_contents);
 887       return (false);
 888     }
 889
 890   if (offset < 0)
 891     {
 892     bad_val:
 893       bfd_set_error (bfd_error_bad_value);
 894       return false;
 895     }
 896   sz = bfd_get_section_size_now (abfd, section);
 897   if ((bfd_size_type) offset > sz
 898       || count > sz
 899       || offset + count > sz)
 900     goto bad_val;
 901
 902   switch (abfd->direction)
 903     {
 904     case read_direction:
 905     case no_direction:
 906       bfd_set_error (bfd_error_invalid_operation);
 907       return false;
 908
 909     case write_direction:
 910       break;
 911
 912     case both_direction:
 913       /* File is opened for update. `output_has_begun' some time ago when
 914            the file was created.  Do not recompute sections sizes or alignments
 915            in _bfd_set_section_content.  */
 916       abfd->output_has_begun = true;
 917       break;
 918     }
 919
 920   if (BFD_SEND (abfd, _bfd_set_section_contents,
 921                 (abfd, section, location, offset, count)))
 922     {
 923       abfd->output_has_begun = true;
 924       return true;
 925     }
 926
 927   return false;
 928 }
 929
 930 /*
 931 FUNCTION
 932         bfd_get_section_contents
 933
 934 SYNOPSIS
 935         boolean bfd_get_section_contents
 936         (bfd *abfd, asection *section, PTR location,
 937          file_ptr offset, bfd_size_type count);
 938
 939 DESCRIPTION
 940         Read data from @var{section} in BFD @var{abfd}
 941         into memory starting at @var{location}. The data is read at an
 942         offset of @var{offset} from the start of the input section,
 943         and is read for @var{count} bytes.
 944
 945         If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
 946         flag set are requested or if the section does not have the
 947         <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
 948         with zeroes. If no errors occur, <<true>> is returned, else
 949         <<false>>.
 950
 951
 952
 953 */
 954 boolean
 955 bfd_get_section_contents (abfd, section, location, offset, count)
 956      bfd *abfd;
 957      sec_ptr section;
 958      PTR location;
 959      file_ptr offset;
 960      bfd_size_type count;
 961 {
 962   bfd_size_type sz;
 963
 964   if (section->flags & SEC_CONSTRUCTOR)
 965     {
 966       memset (location, 0, (unsigned) count);
 967       return true;
 968     }
 969
 970   if (offset < 0)
 971     {
 972     bad_val:
 973       bfd_set_error (bfd_error_bad_value);
 974       return false;
 975     }
 976   /* Even if reloc_done is true, this function reads unrelocated
 977      contents, so we want the raw size.  */
 978   sz = section->_raw_size;
 979   if ((bfd_size_type) offset > sz || count > sz || offset + count > sz)
 980     goto bad_val;
 981
 982   if (count == 0)
 983     /* Don't bother.  */
 984     return true;
 985
 986   if ((section->flags & SEC_HAS_CONTENTS) == 0)
 987     {
 988       memset (location, 0, (unsigned) count);
 989       return true;
 990     }
 991
 992   if ((section->flags & SEC_IN_MEMORY) != 0)
 993     {
 994       memcpy (location, section->contents + offset, (size_t) count);
 995       return true;
 996     }
 997
 998   return BFD_SEND (abfd, _bfd_get_section_contents,
 999                    (abfd, section, location, offset, count));
1000 }
1001
1002 /*
1003 FUNCTION
1004         bfd_copy_private_section_data
1005
1006 SYNOPSIS
1007         boolean bfd_copy_private_section_data(bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
1008
1009 DESCRIPTION
1010         Copy private section information from @var{isec} in the BFD
1011         @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1012         Return <<true>> on success, <<false>> on error.  Possible error
1013         returns are:
1014
1015         o <<bfd_error_no_memory>> -
1016         Not enough memory exists to create private data for @var{osec}.
1017
1018 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1019 .     BFD_SEND (obfd, _bfd_copy_private_section_data, \
1020 .               (ibfd, isection, obfd, osection))
1021 */