bfd/section.c

   1 /* Object file "section" support for the BFD library.
   2    Copyright (C) 1990, 91, 92, 93, 94, 95, 96, 1997
   3    Free Software Foundation, Inc.
   4    Written by Cygnus Support.
   5
   6 This file is part of BFD, the Binary File Descriptor library.
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or
  11 (at your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 /*
  23 SECTION
  24         Sections
  25
  26         The raw data contained within a BFD is maintained through the
  27         section abstraction.  A single BFD may have any number of
  28         sections.  It keeps hold of them by pointing to the first;
  29         each one points to the next in the list.
  30
  31         Sections are supported in BFD in <<section.c>>.
  32
  33 @menu
  34 @* Section Input::
  35 @* Section Output::
  36 @* typedef asection::
  37 @* section prototypes::
  38 @end menu
  39
  40 INODE
  41 Section Input, Section Output, Sections, Sections
  42 SUBSECTION
  43         Section input
  44
  45         When a BFD is opened for reading, the section structures are
  46         created and attached to the BFD.
  47
  48         Each section has a name which describes the section in the
  49         outside world---for example, <<a.out>> would contain at least
  50         three sections, called <<.text>>, <<.data>> and <<.bss>>.
  51
  52         Names need not be unique; for example a COFF file may have several
  53         sections named <<.data>>.
  54
  55         Sometimes a BFD will contain more than the ``natural'' number of
  56         sections. A back end may attach other sections containing
  57         constructor data, or an application may add a section (using
  58         <<bfd_make_section>>) to the sections attached to an already open
  59         BFD. For example, the linker creates an extra section
  60         <<COMMON>> for each input file's BFD to hold information about
  61         common storage.
  62
  63         The raw data is not necessarily read in when
  64         the section descriptor is created. Some targets may leave the
  65         data in place until a <<bfd_get_section_contents>> call is
  66         made. Other back ends may read in all the data at once.  For
  67         example, an S-record file has to be read once to determine the
  68         size of the data. An IEEE-695 file doesn't contain raw data in
  69         sections, but data and relocation expressions intermixed, so
  70         the data area has to be parsed to get out the data and
  71         relocations.
  72
  73 INODE
  74 Section Output, typedef asection, Section Input, Sections
  75
  76 SUBSECTION
  77         Section output
  78
  79         To write a new object style BFD, the various sections to be
  80         written have to be created. They are attached to the BFD in
  81         the same way as input sections; data is written to the
  82         sections using <<bfd_set_section_contents>>.
  83
  84         Any program that creates or combines sections (e.g., the assembler
  85         and linker) must use the <<asection>> fields <<output_section>> and
  86         <<output_offset>> to indicate the file sections to which each
  87         section must be written.  (If the section is being created from
  88         scratch, <<output_section>> should probably point to the section
  89         itself and <<output_offset>> should probably be zero.)
  90
  91         The data to be written comes from input sections attached
  92         (via <<output_section>> pointers) to
  93         the output sections.  The output section structure can be
  94         considered a filter for the input section: the output section
  95         determines the vma of the output data and the name, but the
  96         input section determines the offset into the output section of
  97         the data to be written.
  98
  99         E.g., to create a section "O", starting at 0x100, 0x123 long,
 100         containing two subsections, "A" at offset 0x0 (i.e., at vma
 101         0x100) and "B" at offset 0x20 (i.e., at vma 0x120) the <<asection>>
 102         structures would look like:
 103
 104 |   section name          "A"
 105 |     output_offset   0x00
 106 |     size            0x20
 107 |     output_section ----------->  section name    "O"
 108 |                             |    vma             0x100
 109 |   section name          "B" |    size            0x123
 110 |     output_offset   0x20    |
 111 |     size            0x103   |
 112 |     output_section  --------|
 113
 114
 115 SUBSECTION
 116         Link orders
 117
 118         The data within a section is stored in a @dfn{link_order}.
 119         These are much like the fixups in <<gas>>.  The link_order
 120         abstraction allows a section to grow and shrink within itself.
 121
 122         A link_order knows how big it is, and which is the next
 123         link_order and where the raw data for it is; it also points to
 124         a list of relocations which apply to it.
 125
 126         The link_order is used by the linker to perform relaxing on
 127         final code.  The compiler creates code which is as big as
 128         necessary to make it work without relaxing, and the user can
 129         select whether to relax.  Sometimes relaxing takes a lot of
 130         time.  The linker runs around the relocations to see if any
 131         are attached to data which can be shrunk, if so it does it on
 132         a link_order by link_order basis.
 133
 134 */
 135
 136
 137 #include "bfd.h"
 138 #include "sysdep.h"
 139 #include "libbfd.h"
 140 #include "bfdlink.h"
 141
 142 /*
 143 DOCDD
 144 INODE
 145 typedef asection, section prototypes, Section Output, Sections
 146 SUBSECTION
 147         typedef asection
 148
 149         Here is the section structure:
 150
 151 CODE_FRAGMENT
 152 .
 153 .typedef struct sec
 154 .{
 155 .        {* The name of the section; the name isn't a copy, the pointer is
 156 .        the same as that passed to bfd_make_section. *}
 157 .
 158 .    CONST char *name;
 159 .
 160 .        {* Which section is it; 0..nth.      *}
 161 .
 162 .   int index;
 163 .
 164 .        {* The next section in the list belonging to the BFD, or NULL. *}
 165 .
 166 .    struct sec *next;
 167 .
 168 .        {* The field flags contains attributes of the section. Some
 169 .           flags are read in from the object file, and some are
 170 .           synthesized from other information.  *}
 171 .
 172 .    flagword flags;
 173 .
 174 .#define SEC_NO_FLAGS   0x000
 175 .
 176 .        {* Tells the OS to allocate space for this section when loading.
 177 .           This is clear for a section containing debug information
 178 .           only. *}
 179 .#define SEC_ALLOC      0x001
 180 .
 181 .        {* Tells the OS to load the section from the file when loading.
 182 .           This is clear for a .bss section. *}
 183 .#define SEC_LOAD       0x002
 184 .
 185 .        {* The section contains data still to be relocated, so there is
 186 .           some relocation information too. *}
 187 .#define SEC_RELOC      0x004
 188 .
 189 .#if 0   {* Obsolete ? *}
 190 .#define SEC_BALIGN     0x008
 191 .#endif
 192 .
 193 .        {* A signal to the OS that the section contains read only
 194 .          data. *}
 195 .#define SEC_READONLY   0x010
 196 .
 197 .        {* The section contains code only. *}
 198 .#define SEC_CODE       0x020
 199 .
 200 .        {* The section contains data only. *}
 201 .#define SEC_DATA       0x040
 202 .
 203 .        {* The section will reside in ROM. *}
 204 .#define SEC_ROM        0x080
 205 .
 206 .        {* The section contains constructor information. This section
 207 .           type is used by the linker to create lists of constructors and
 208 .           destructors used by <<g++>>. When a back end sees a symbol
 209 .           which should be used in a constructor list, it creates a new
 210 .           section for the type of name (e.g., <<__CTOR_LIST__>>), attaches
 211 .           the symbol to it, and builds a relocation. To build the lists
 212 .           of constructors, all the linker has to do is catenate all the
 213 .           sections called <<__CTOR_LIST__>> and relocate the data
 214 .           contained within - exactly the operations it would peform on
 215 .           standard data. *}
 216 .#define SEC_CONSTRUCTOR 0x100
 217 .
 218 .        {* The section is a constructor, and should be placed at the
 219 .          end of the text, data, or bss section(?). *}
 220 .#define SEC_CONSTRUCTOR_TEXT 0x1100
 221 .#define SEC_CONSTRUCTOR_DATA 0x2100
 222 .#define SEC_CONSTRUCTOR_BSS  0x3100
 223 .
 224 .        {* The section has contents - a data section could be
 225 .           <<SEC_ALLOC>> | <<SEC_HAS_CONTENTS>>; a debug section could be
 226 .           <<SEC_HAS_CONTENTS>> *}
 227 .#define SEC_HAS_CONTENTS 0x200
 228 .
 229 .        {* An instruction to the linker to not output the section
 230 .           even if it has information which would normally be written. *}
 231 .#define SEC_NEVER_LOAD 0x400
 232 .
 233 .        {* The section is a COFF shared library section.  This flag is
 234 .           only for the linker.  If this type of section appears in
 235 .           the input file, the linker must copy it to the output file
 236 .           without changing the vma or size.  FIXME: Although this
 237 .           was originally intended to be general, it really is COFF
 238 .           specific (and the flag was renamed to indicate this).  It
 239 .           might be cleaner to have some more general mechanism to
 240 .           allow the back end to control what the linker does with
 241 .           sections. *}
 242 .#define SEC_COFF_SHARED_LIBRARY 0x800
 243 .
 244 .        {* The section contains common symbols (symbols may be defined
 245 .           multiple times, the value of a symbol is the amount of
 246 .           space it requires, and the largest symbol value is the one
 247 .           used).  Most targets have exactly one of these (which we
 248 .           translate to bfd_com_section_ptr), but ECOFF has two. *}
 249 .#define SEC_IS_COMMON 0x8000
 250 .
 251 .        {* The section contains only debugging information.  For
 252 .           example, this is set for ELF .debug and .stab sections.
 253 .           strip tests this flag to see if a section can be
 254 .           discarded. *}
 255 .#define SEC_DEBUGGING 0x10000
 256 .
 257 .        {* The contents of this section are held in memory pointed to
 258 .           by the contents field.  This is checked by
 259 .           bfd_get_section_contents, and the data is retrieved from
 260 .           memory if appropriate.  *}
 261 .#define SEC_IN_MEMORY 0x20000
 262 .
 263 .        {* The contents of this section are to be excluded by the
 264 .           linker for executable and shared objects unless those
 265 .           objects are to be further relocated.  *}
 266 .#define SEC_EXCLUDE 0x40000
 267 .
 268 .       {* The contents of this section are to be sorted by the
 269 .          based on the address specified in the associated symbol
 270 .          table.  *}
 271 .#define SEC_SORT_ENTRIES 0x80000
 272 .
 273 .       {* When linking, duplicate sections of the same name should be
 274 .          discarded, rather than being combined into a single section as
 275 .          is usually done.  This is similar to how common symbols are
 276 .          handled.  See SEC_LINK_DUPLICATES below.  *}
 277 .#define SEC_LINK_ONCE 0x100000
 278 .
 279 .       {* If SEC_LINK_ONCE is set, this bitfield describes how the linker
 280 .          should handle duplicate sections.  *}
 281 .#define SEC_LINK_DUPLICATES 0x600000
 282 .
 283 .       {* This value for SEC_LINK_DUPLICATES means that duplicate
 284 .          sections with the same name should simply be discarded. *}
 285 .#define SEC_LINK_DUPLICATES_DISCARD 0x0
 286 .
 287 .       {* This value for SEC_LINK_DUPLICATES means that the linker
 288 .          should warn if there are any duplicate sections, although
 289 .          it should still only link one copy.  *}
 290 .#define SEC_LINK_DUPLICATES_ONE_ONLY 0x200000
 291 .
 292 .       {* This value for SEC_LINK_DUPLICATES means that the linker
 293 .          should warn if any duplicate sections are a different size.  *}
 294 .#define SEC_LINK_DUPLICATES_SAME_SIZE 0x400000
 295 .
 296 .       {* This value for SEC_LINK_DUPLICATES means that the linker
 297 .          should warn if any duplicate sections contain different
 298 .          contents.  *}
 299 .#define SEC_LINK_DUPLICATES_SAME_CONTENTS 0x600000
 300 .
 301 .       {* This section was created by the linker as part of dynamic
 302 .          relocation or other arcane processing.  It is skipped when
 303 .          going through the first-pass output, trusting that someone
 304 .          else up the line will take care of it later.  *}
 305 .#define SEC_LINKER_CREATED 0x800000
 306 .
 307 .       {* This section should not be subject to garbage collection.  *}
 308 .#define SEC_KEEP 0x1000000
 309 .
 310 .       {*  End of section flags.  *}
 311 .
 312 .       {* Some internal packed boolean fields.  *}
 313 .
 314 .       {* See the vma field.  *}
 315 .       unsigned int user_set_vma : 1;
 316 .
 317 .       {* Whether relocations have been processed.  *}
 318 .       unsigned int reloc_done : 1;
 319 .
 320 .       {* A mark flag used by some of the linker backends.  *}
 321 .       unsigned int linker_mark : 1;
 322 .
 323 .       {* A mark flag used by some linker backends for garbage collection.  *}
 324 .       unsigned int gc_mark : 1;
 325 .
 326 .       {* End of internal packed boolean fields.  *}
 327 .
 328 .       {*  The virtual memory address of the section - where it will be
 329 .           at run time.  The symbols are relocated against this.  The
 330 .           user_set_vma flag is maintained by bfd; if it's not set, the
 331 .           backend can assign addresses (for example, in <<a.out>>, where
 332 .           the default address for <<.data>> is dependent on the specific
 333 .           target and various flags).  *}
 334 .
 335 .   bfd_vma vma;
 336 .
 337 .       {*  The load address of the section - where it would be in a
 338 .           rom image; really only used for writing section header
 339 .           information. *}
 340 .
 341 .   bfd_vma lma;
 342 .
 343 .        {* The size of the section in bytes, as it will be output.
 344 .           contains a value even if the section has no contents (e.g., the
 345 .           size of <<.bss>>). This will be filled in after relocation *}
 346 .
 347 .   bfd_size_type _cooked_size;
 348 .
 349 .        {* The original size on disk of the section, in bytes.  Normally this
 350 .           value is the same as the size, but if some relaxing has
 351 .           been done, then this value will be bigger.  *}
 352 .
 353 .   bfd_size_type _raw_size;
 354 .
 355 .        {* If this section is going to be output, then this value is the
 356 .           offset into the output section of the first byte in the input
 357 .           section. E.g., if this was going to start at the 100th byte in
 358 .           the output section, this value would be 100. *}
 359 .
 360 .   bfd_vma output_offset;
 361 .
 362 .        {* The output section through which to map on output. *}
 363 .
 364 .   struct sec *output_section;
 365 .
 366 .        {* The alignment requirement of the section, as an exponent of 2 -
 367 .           e.g., 3 aligns to 2^3 (or 8). *}
 368 .
 369 .   unsigned int alignment_power;
 370 .
 371 .        {* If an input section, a pointer to a vector of relocation
 372 .           records for the data in this section. *}
 373 .
 374 .   struct reloc_cache_entry *relocation;
 375 .
 376 .        {* If an output section, a pointer to a vector of pointers to
 377 .           relocation records for the data in this section. *}
 378 .
 379 .   struct reloc_cache_entry **orelocation;
 380 .
 381 .        {* The number of relocation records in one of the above  *}
 382 .
 383 .   unsigned reloc_count;
 384 .
 385 .        {* Information below is back end specific - and not always used
 386 .           or updated.  *}
 387 .
 388 .        {* File position of section data    *}
 389 .
 390 .   file_ptr filepos;
 391 .
 392 .        {* File position of relocation info *}
 393 .
 394 .   file_ptr rel_filepos;
 395 .
 396 .        {* File position of line data       *}
 397 .
 398 .   file_ptr line_filepos;
 399 .
 400 .        {* Pointer to data for applications *}
 401 .
 402 .   PTR userdata;
 403 .
 404 .        {* If the SEC_IN_MEMORY flag is set, this points to the actual
 405 .           contents.  *}
 406 .   unsigned char *contents;
 407 .
 408 .        {* Attached line number information *}
 409 .
 410 .   alent *lineno;
 411 .
 412 .        {* Number of line number records   *}
 413 .
 414 .   unsigned int lineno_count;
 415 .
 416 .        {* When a section is being output, this value changes as more
 417 .           linenumbers are written out *}
 418 .
 419 .   file_ptr moving_line_filepos;
 420 .
 421 .        {* What the section number is in the target world  *}
 422 .
 423 .   int target_index;
 424 .
 425 .   PTR used_by_bfd;
 426 .
 427 .        {* If this is a constructor section then here is a list of the
 428 .           relocations created to relocate items within it. *}
 429 .
 430 .   struct relent_chain *constructor_chain;
 431 .
 432 .        {* The BFD which owns the section. *}
 433 .
 434 .   bfd *owner;
 435 .
 436 .        {* A symbol which points at this section only *}
 437 .   struct symbol_cache_entry *symbol;
 438 .   struct symbol_cache_entry **symbol_ptr_ptr;
 439 .
 440 .   struct bfd_link_order *link_order_head;
 441 .   struct bfd_link_order *link_order_tail;
 442 .} asection ;
 443 .
 444 .    {* These sections are global, and are managed by BFD.  The application
 445 .       and target back end are not permitted to change the values in
 446 .       these sections.  New code should use the section_ptr macros rather
 447 .       than referring directly to the const sections.  The const sections
 448 .       may eventually vanish.  *}
 449 .#define BFD_ABS_SECTION_NAME "*ABS*"
 450 .#define BFD_UND_SECTION_NAME "*UND*"
 451 .#define BFD_COM_SECTION_NAME "*COM*"
 452 .#define BFD_IND_SECTION_NAME "*IND*"
 453 .
 454 .    {* the absolute section *}
 455 .extern const asection bfd_abs_section;
 456 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
 457 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
 458 .    {* Pointer to the undefined section *}
 459 .extern const asection bfd_und_section;
 460 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
 461 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
 462 .    {* Pointer to the common section *}
 463 .extern const asection bfd_com_section;
 464 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
 465 .    {* Pointer to the indirect section *}
 466 .extern const asection bfd_ind_section;
 467 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
 468 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
 469 .
 470 .extern const struct symbol_cache_entry * const bfd_abs_symbol;
 471 .extern const struct symbol_cache_entry * const bfd_com_symbol;
 472 .extern const struct symbol_cache_entry * const bfd_und_symbol;
 473 .extern const struct symbol_cache_entry * const bfd_ind_symbol;
 474 .#define bfd_get_section_size_before_reloc(section) \
 475 .     (section->reloc_done ? (abort(),1): (section)->_raw_size)
 476 .#define bfd_get_section_size_after_reloc(section) \
 477 .     ((section->reloc_done) ? (section)->_cooked_size: (abort(),1))
 478 */
 479
 480 /* These symbols are global, not specific to any BFD.  Therefore, anything
 481    that tries to change them is broken, and should be repaired.  */
 482 static const asymbol global_syms[] =
 483 {
 484  /* the_bfd, name, value, attr, section [, udata] */
 485   {0, BFD_COM_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_com_section},
 486   {0, BFD_UND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_und_section},
 487   {0, BFD_ABS_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_abs_section},
 488   {0, BFD_IND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_ind_section},
 489 };
 490
 491 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
 492   const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
 493   const asection SEC = \
 494     { NAME, 0, 0, FLAGS, 0, 0, 0, 0, 0, 0, 0, 0, 0, (asection *) &SEC, \
 495       0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0, \
 496       (asymbol *) &global_syms[IDX], (asymbol **) &SYM, 0, 0 }
 497
 498 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
 499              BFD_COM_SECTION_NAME, 0);
 500 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
 501 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
 502 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
 503 #undef STD_SECTION
 504
 505 /*
 506 DOCDD
 507 INODE
 508 section prototypes,  , typedef asection, Sections
 509 SUBSECTION
 510         Section prototypes
 511
 512 These are the functions exported by the section handling part of BFD.
 513 */
 514
 515 /*
 516 FUNCTION
 517         bfd_get_section_by_name
 518
 519 SYNOPSIS
 520         asection *bfd_get_section_by_name(bfd *abfd, CONST char *name);
 521
 522 DESCRIPTION
 523         Run through @var{abfd} and return the one of the
 524         <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
 525         @xref{Sections}, for more information.
 526
 527         This should only be used in special cases; the normal way to process
 528         all sections of a given name is to use <<bfd_map_over_sections>> and
 529         <<strcmp>> on the name (or better yet, base it on the section flags
 530         or something else) for each section.
 531 */
 532
 533 asection *
 534 bfd_get_section_by_name (abfd, name)
 535      bfd *abfd;
 536      CONST char *name;
 537 {
 538   asection *sect;
 539
 540   for (sect = abfd->sections; sect != NULL; sect = sect->next)
 541     if (!strcmp (sect->name, name))
 542       return sect;
 543   return NULL;
 544 }
 545
 546
 547 /*
 548 FUNCTION
 549         bfd_make_section_old_way
 550
 551 SYNOPSIS
 552         asection *bfd_make_section_old_way(bfd *abfd, CONST char *name);
 553
 554 DESCRIPTION
 555         Create a new empty section called @var{name}
 556         and attach it to the end of the chain of sections for the
 557         BFD @var{abfd}. An attempt to create a section with a name which
 558         is already in use returns its pointer without changing the
 559         section chain.
 560
 561         It has the funny name since this is the way it used to be
 562         before it was rewritten....
 563
 564         Possible errors are:
 565         o <<bfd_error_invalid_operation>> -
 566         If output has already started for this BFD.
 567         o <<bfd_error_no_memory>> -
 568         If memory allocation fails.
 569
 570 */
 571
 572
 573 asection *
 574 bfd_make_section_old_way (abfd, name)
 575      bfd *abfd;
 576      CONST char *name;
 577 {
 578   asection *sec = bfd_get_section_by_name (abfd, name);
 579   if (sec == (asection *) NULL)
 580     {
 581       sec = bfd_make_section (abfd, name);
 582     }
 583   return sec;
 584 }
 585
 586 /*
 587 FUNCTION
 588         bfd_make_section_anyway
 589
 590 SYNOPSIS
 591         asection *bfd_make_section_anyway(bfd *abfd, CONST char *name);
 592
 593 DESCRIPTION
 594    Create a new empty section called @var{name} and attach it to the end of
 595    the chain of sections for @var{abfd}.  Create a new section even if there
 596    is already a section with that name.
 597
 598    Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
 599    o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
 600    o <<bfd_error_no_memory>> - If memory allocation fails.
 601 */
 602
 603 sec_ptr
 604 bfd_make_section_anyway (abfd, name)
 605      bfd *abfd;
 606      CONST char *name;
 607 {
 608   asection *newsect;
 609   asection **prev = &abfd->sections;
 610   asection *sect = abfd->sections;
 611
 612   if (abfd->output_has_begun)
 613     {
 614       bfd_set_error (bfd_error_invalid_operation);
 615       return NULL;
 616     }
 617
 618   while (sect)
 619     {
 620       prev = &sect->next;
 621       sect = sect->next;
 622     }
 623
 624   newsect = (asection *) bfd_zalloc (abfd, sizeof (asection));
 625   if (newsect == NULL)
 626     return NULL;
 627
 628   newsect->name = name;
 629   newsect->index = abfd->section_count++;
 630   newsect->flags = SEC_NO_FLAGS;
 631
 632   newsect->userdata = NULL;
 633   newsect->contents = NULL;
 634   newsect->next = (asection *) NULL;
 635   newsect->relocation = (arelent *) NULL;
 636   newsect->reloc_count = 0;
 637   newsect->line_filepos = 0;
 638   newsect->owner = abfd;
 639
 640   /* Create a symbol whos only job is to point to this section. This is
 641      useful for things like relocs which are relative to the base of a
 642      section.  */
 643   newsect->symbol = bfd_make_empty_symbol (abfd);
 644   if (newsect->symbol == NULL)
 645     return NULL;
 646   newsect->symbol->name = name;
 647   newsect->symbol->value = 0;
 648   newsect->symbol->section = newsect;
 649   newsect->symbol->flags = BSF_SECTION_SYM;
 650
 651   newsect->symbol_ptr_ptr = &newsect->symbol;
 652
 653   if (BFD_SEND (abfd, _new_section_hook, (abfd, newsect)) != true)
 654     {
 655       free (newsect);
 656       return NULL;
 657     }
 658
 659   *prev = newsect;
 660   return newsect;
 661 }
 662
 663 /*
 664 FUNCTION
 665         bfd_make_section
 666
 667 SYNOPSIS
 668         asection *bfd_make_section(bfd *, CONST char *name);
 669
 670 DESCRIPTION
 671    Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
 672    bfd_set_error ()) without changing the section chain if there is already a
 673    section named @var{name}.  If there is an error, return <<NULL>> and set
 674    <<bfd_error>>.
 675 */
 676
 677 asection *
 678 bfd_make_section (abfd, name)
 679      bfd *abfd;
 680      CONST char *name;
 681 {
 682   asection *sect = abfd->sections;
 683
 684   if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
 685     {
 686       return bfd_abs_section_ptr;
 687     }
 688   if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
 689     {
 690       return bfd_com_section_ptr;
 691     }
 692   if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
 693     {
 694       return bfd_und_section_ptr;
 695     }
 696
 697   if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
 698     {
 699       return bfd_ind_section_ptr;
 700     }
 701
 702   while (sect)
 703     {
 704       if (!strcmp (sect->name, name))
 705         return NULL;
 706       sect = sect->next;
 707     }
 708
 709   /* The name is not already used; go ahead and make a new section.  */
 710   return bfd_make_section_anyway (abfd, name);
 711 }
 712
 713
 714 /*
 715 FUNCTION
 716         bfd_set_section_flags
 717
 718 SYNOPSIS
 719         boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags);
 720
 721 DESCRIPTION
 722         Set the attributes of the section @var{sec} in the BFD
 723         @var{abfd} to the value @var{flags}. Return <<true>> on success,
 724         <<false>> on error. Possible error returns are:
 725
 726         o <<bfd_error_invalid_operation>> -
 727         The section cannot have one or more of the attributes
 728         requested. For example, a .bss section in <<a.out>> may not
 729         have the <<SEC_HAS_CONTENTS>> field set.
 730
 731 */
 732
 733 /*ARGSUSED*/
 734 boolean
 735 bfd_set_section_flags (abfd, section, flags)
 736      bfd *abfd;
 737      sec_ptr section;
 738      flagword flags;
 739 {
 740 #if 0
 741   /* If you try to copy a text section from an input file (where it
 742      has the SEC_CODE flag set) to an output file, this loses big if
 743      the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
 744      set - which it doesn't, at least not for a.out.  FIXME */
 745
 746   if ((flags & bfd_applicable_section_flags (abfd)) != flags)
 747     {
 748       bfd_set_error (bfd_error_invalid_operation);
 749       return false;
 750     }
 751 #endif
 752
 753   section->flags = flags;
 754   return true;
 755 }
 756
 757
 758 /*
 759 FUNCTION
 760         bfd_map_over_sections
 761
 762 SYNOPSIS
 763         void bfd_map_over_sections(bfd *abfd,
 764                                    void (*func)(bfd *abfd,
 765                                                 asection *sect,
 766                                                 PTR obj),
 767                                    PTR obj);
 768
 769 DESCRIPTION
 770         Call the provided function @var{func} for each section
 771         attached to the BFD @var{abfd}, passing @var{obj} as an
 772         argument. The function will be called as if by
 773
 774 |       func(abfd, the_section, obj);
 775
 776         This is the prefered method for iterating over sections; an
 777         alternative would be to use a loop:
 778
 779 |          section *p;
 780 |          for (p = abfd->sections; p != NULL; p = p->next)
 781 |             func(abfd, p, ...)
 782
 783
 784 */
 785
 786 /*VARARGS2*/
 787 void
 788 bfd_map_over_sections (abfd, operation, user_storage)
 789      bfd *abfd;
 790      void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj));
 791      PTR user_storage;
 792 {
 793   asection *sect;
 794   unsigned int i = 0;
 795
 796   for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
 797     (*operation) (abfd, sect, user_storage);
 798
 799   if (i != abfd->section_count) /* Debugging */
 800     abort ();
 801 }
 802
 803
 804 /*
 805 FUNCTION
 806         bfd_set_section_size
 807
 808 SYNOPSIS
 809         boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val);
 810
 811 DESCRIPTION
 812         Set @var{sec} to the size @var{val}. If the operation is
 813         ok, then <<true>> is returned, else <<false>>.
 814
 815         Possible error returns:
 816         o <<bfd_error_invalid_operation>> -
 817         Writing has started to the BFD, so setting the size is invalid.
 818
 819 */
 820
 821 boolean
 822 bfd_set_section_size (abfd, ptr, val)
 823      bfd *abfd;
 824      sec_ptr ptr;
 825      bfd_size_type val;
 826 {
 827   /* Once you've started writing to any section you cannot create or change
 828      the size of any others. */
 829
 830   if (abfd->output_has_begun)
 831     {
 832       bfd_set_error (bfd_error_invalid_operation);
 833       return false;
 834     }
 835
 836   ptr->_cooked_size = val;
 837   ptr->_raw_size = val;
 838
 839   return true;
 840 }
 841
 842 /*
 843 FUNCTION
 844         bfd_set_section_contents
 845
 846 SYNOPSIS
 847         boolean bfd_set_section_contents
 848          (bfd *abfd,
 849          asection *section,
 850          PTR data,
 851          file_ptr offset,
 852          bfd_size_type count);
 853
 854
 855 DESCRIPTION
 856         Sets the contents of the section @var{section} in BFD
 857         @var{abfd} to the data starting in memory at @var{data}. The
 858         data is written to the output section starting at offset
 859         @var{offset} for @var{count} bytes.
 860
 861
 862
 863         Normally <<true>> is returned, else <<false>>. Possible error
 864         returns are:
 865         o <<bfd_error_no_contents>> -
 866         The output section does not have the <<SEC_HAS_CONTENTS>>
 867         attribute, so nothing can be written to it.
 868         o and some more too
 869
 870         This routine is front end to the back end function
 871         <<_bfd_set_section_contents>>.
 872
 873
 874 */
 875
 876 #define bfd_get_section_size_now(abfd,sec) \
 877 (sec->reloc_done \
 878  ? bfd_get_section_size_after_reloc (sec) \
 879  : bfd_get_section_size_before_reloc (sec))
 880
 881 boolean
 882 bfd_set_section_contents (abfd, section, location, offset, count)
 883      bfd *abfd;
 884      sec_ptr section;
 885      PTR location;
 886      file_ptr offset;
 887      bfd_size_type count;
 888 {
 889   bfd_size_type sz;
 890
 891   if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
 892     {
 893       bfd_set_error (bfd_error_no_contents);
 894       return (false);
 895     }
 896
 897   if (offset < 0)
 898     {
 899     bad_val:
 900       bfd_set_error (bfd_error_bad_value);
 901       return false;
 902     }
 903   sz = bfd_get_section_size_now (abfd, section);
 904   if ((bfd_size_type) offset > sz
 905       || count > sz
 906       || offset + count > sz)
 907     goto bad_val;
 908
 909   switch (abfd->direction)
 910     {
 911     case read_direction:
 912     case no_direction:
 913       bfd_set_error (bfd_error_invalid_operation);
 914       return false;
 915
 916     case write_direction:
 917       break;
 918
 919     case both_direction:
 920       /* File is opened for update. `output_has_begun' some time ago when
 921            the file was created.  Do not recompute sections sizes or alignments
 922            in _bfd_set_section_content.  */
 923       abfd->output_has_begun = true;
 924       break;
 925     }
 926
 927   if (BFD_SEND (abfd, _bfd_set_section_contents,
 928                 (abfd, section, location, offset, count)))
 929     {
 930       abfd->output_has_begun = true;
 931       return true;
 932     }
 933
 934   return false;
 935 }
 936
 937 /*
 938 FUNCTION
 939         bfd_get_section_contents
 940
 941 SYNOPSIS
 942         boolean bfd_get_section_contents
 943         (bfd *abfd, asection *section, PTR location,
 944          file_ptr offset, bfd_size_type count);
 945
 946 DESCRIPTION
 947         Read data from @var{section} in BFD @var{abfd}
 948         into memory starting at @var{location}. The data is read at an
 949         offset of @var{offset} from the start of the input section,
 950         and is read for @var{count} bytes.
 951
 952         If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
 953         flag set are requested or if the section does not have the
 954         <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
 955         with zeroes. If no errors occur, <<true>> is returned, else
 956         <<false>>.
 957
 958
 959
 960 */
 961 boolean
 962 bfd_get_section_contents (abfd, section, location, offset, count)
 963      bfd *abfd;
 964      sec_ptr section;
 965      PTR location;
 966      file_ptr offset;
 967      bfd_size_type count;
 968 {
 969   bfd_size_type sz;
 970
 971   if (section->flags & SEC_CONSTRUCTOR)
 972     {
 973       memset (location, 0, (unsigned) count);
 974       return true;
 975     }
 976
 977   if (offset < 0)
 978     {
 979     bad_val:
 980       bfd_set_error (bfd_error_bad_value);
 981       return false;
 982     }
 983   /* Even if reloc_done is true, this function reads unrelocated
 984      contents, so we want the raw size.  */
 985   sz = section->_raw_size;
 986   if ((bfd_size_type) offset > sz || count > sz || offset + count > sz)
 987     goto bad_val;
 988
 989   if (count == 0)
 990     /* Don't bother.  */
 991     return true;
 992
 993   if ((section->flags & SEC_HAS_CONTENTS) == 0)
 994     {
 995       memset (location, 0, (unsigned) count);
 996       return true;
 997     }
 998
 999   if ((section->flags & SEC_IN_MEMORY) != 0)
1000     {
1001       memcpy (location, section->contents + offset, (size_t) count);
1002       return true;
1003     }
1004
1005   return BFD_SEND (abfd, _bfd_get_section_contents,
1006                    (abfd, section, location, offset, count));
1007 }
1008
1009 /*
1010 FUNCTION
1011         bfd_copy_private_section_data
1012
1013 SYNOPSIS
1014         boolean bfd_copy_private_section_data(bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
1015
1016 DESCRIPTION
1017         Copy private section information from @var{isec} in the BFD
1018         @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1019         Return <<true>> on success, <<false>> on error.  Possible error
1020         returns are:
1021
1022         o <<bfd_error_no_memory>> -
1023         Not enough memory exists to create private data for @var{osec}.
1024
1025 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1026 .     BFD_SEND (obfd, _bfd_copy_private_section_data, \
1027 .               (ibfd, isection, obfd, osection))
1028 */
1029
1030 /*
1031 FUNCTION
1032         _bfd_strip_section_from_output
1033
1034 SYNOPSIS
1035         void _bfd_strip_section_from_output
1036         (asection *section);
1037
1038 DESCRIPTION
1039         Remove @var{section} from the output.  If the output section becomes
1040         empty, remove it from the output bfd.
1041 */
1042 void
1043 _bfd_strip_section_from_output (s)
1044      asection *s;
1045 {
1046   asection **spp, *os;
1047   struct bfd_link_order *p, *pp;
1048
1049   os = s->output_section;
1050   for (p = os->link_order_head, pp = NULL; p != NULL; pp = p, p = p->next)
1051     if (p->type == bfd_indirect_link_order
1052         && p->u.indirect.section == s)
1053       {
1054         /* Excise the input section.  */
1055         if (pp)
1056           pp->next = p->next;
1057         else
1058           os->link_order_head = p->next;
1059         if (!p->next)
1060           os->link_order_tail = pp;
1061
1062         if (!os->link_order_head)
1063           {
1064             /* Excise the output section.  */
1065             for (spp = &os->owner->sections; *spp; spp = &(*spp)->next)
1066               if (*spp == os)
1067                 {
1068                   *spp = os->next;
1069                   os->owner->section_count--;
1070                   break;
1071                 }
1072           }
1073         break;
1074       }
1075 }