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 .       {* This section contains "short" data, and should be placed
 311 .          "near" the GP.  *}
 312 .#define SEC_SHORT 0x2000000
 313 .
 314 .       {*  End of section flags.  *}
 315 .
 316 .       {* Some internal packed boolean fields.  *}
 317 .
 318 .       {* See the vma field.  *}
 319 .       unsigned int user_set_vma : 1;
 320 .
 321 .       {* Whether relocations have been processed.  *}
 322 .       unsigned int reloc_done : 1;
 323 .
 324 .       {* A mark flag used by some of the linker backends.  *}
 325 .       unsigned int linker_mark : 1;
 326 .
 327 .       {* A mark flag used by some linker backends for garbage collection.  *}
 328 .       unsigned int gc_mark : 1;
 329 .
 330 .       {* End of internal packed boolean fields.  *}
 331 .
 332 .       {*  The virtual memory address of the section - where it will be
 333 .           at run time.  The symbols are relocated against this.  The
 334 .           user_set_vma flag is maintained by bfd; if it's not set, the
 335 .           backend can assign addresses (for example, in <<a.out>>, where
 336 .           the default address for <<.data>> is dependent on the specific
 337 .           target and various flags).  *}
 338 .
 339 .   bfd_vma vma;
 340 .
 341 .       {*  The load address of the section - where it would be in a
 342 .           rom image; really only used for writing section header
 343 .           information. *}
 344 .
 345 .   bfd_vma lma;
 346 .
 347 .        {* The size of the section in bytes, as it will be output.
 348 .           contains a value even if the section has no contents (e.g., the
 349 .           size of <<.bss>>). This will be filled in after relocation *}
 350 .
 351 .   bfd_size_type _cooked_size;
 352 .
 353 .        {* The original size on disk of the section, in bytes.  Normally this
 354 .           value is the same as the size, but if some relaxing has
 355 .           been done, then this value will be bigger.  *}
 356 .
 357 .   bfd_size_type _raw_size;
 358 .
 359 .        {* If this section is going to be output, then this value is the
 360 .           offset into the output section of the first byte in the input
 361 .           section. E.g., if this was going to start at the 100th byte in
 362 .           the output section, this value would be 100. *}
 363 .
 364 .   bfd_vma output_offset;
 365 .
 366 .        {* The output section through which to map on output. *}
 367 .
 368 .   struct sec *output_section;
 369 .
 370 .        {* The alignment requirement of the section, as an exponent of 2 -
 371 .           e.g., 3 aligns to 2^3 (or 8). *}
 372 .
 373 .   unsigned int alignment_power;
 374 .
 375 .        {* If an input section, a pointer to a vector of relocation
 376 .           records for the data in this section. *}
 377 .
 378 .   struct reloc_cache_entry *relocation;
 379 .
 380 .        {* If an output section, a pointer to a vector of pointers to
 381 .           relocation records for the data in this section. *}
 382 .
 383 .   struct reloc_cache_entry **orelocation;
 384 .
 385 .        {* The number of relocation records in one of the above  *}
 386 .
 387 .   unsigned reloc_count;
 388 .
 389 .        {* Information below is back end specific - and not always used
 390 .           or updated.  *}
 391 .
 392 .        {* File position of section data    *}
 393 .
 394 .   file_ptr filepos;
 395 .
 396 .        {* File position of relocation info *}
 397 .
 398 .   file_ptr rel_filepos;
 399 .
 400 .        {* File position of line data       *}
 401 .
 402 .   file_ptr line_filepos;
 403 .
 404 .        {* Pointer to data for applications *}
 405 .
 406 .   PTR userdata;
 407 .
 408 .        {* If the SEC_IN_MEMORY flag is set, this points to the actual
 409 .           contents.  *}
 410 .   unsigned char *contents;
 411 .
 412 .        {* Attached line number information *}
 413 .
 414 .   alent *lineno;
 415 .
 416 .        {* Number of line number records   *}
 417 .
 418 .   unsigned int lineno_count;
 419 .
 420 .        {* When a section is being output, this value changes as more
 421 .           linenumbers are written out *}
 422 .
 423 .   file_ptr moving_line_filepos;
 424 .
 425 .        {* What the section number is in the target world  *}
 426 .
 427 .   int target_index;
 428 .
 429 .   PTR used_by_bfd;
 430 .
 431 .        {* If this is a constructor section then here is a list of the
 432 .           relocations created to relocate items within it. *}
 433 .
 434 .   struct relent_chain *constructor_chain;
 435 .
 436 .        {* The BFD which owns the section. *}
 437 .
 438 .   bfd *owner;
 439 .
 440 .        {* A symbol which points at this section only *}
 441 .   struct symbol_cache_entry *symbol;
 442 .   struct symbol_cache_entry **symbol_ptr_ptr;
 443 .
 444 .   struct bfd_link_order *link_order_head;
 445 .   struct bfd_link_order *link_order_tail;
 446 .} asection ;
 447 .
 448 .    {* These sections are global, and are managed by BFD.  The application
 449 .       and target back end are not permitted to change the values in
 450 .       these sections.  New code should use the section_ptr macros rather
 451 .       than referring directly to the const sections.  The const sections
 452 .       may eventually vanish.  *}
 453 .#define BFD_ABS_SECTION_NAME "*ABS*"
 454 .#define BFD_UND_SECTION_NAME "*UND*"
 455 .#define BFD_COM_SECTION_NAME "*COM*"
 456 .#define BFD_IND_SECTION_NAME "*IND*"
 457 .
 458 .    {* the absolute section *}
 459 .extern const asection bfd_abs_section;
 460 .#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)
 461 .#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)
 462 .    {* Pointer to the undefined section *}
 463 .extern const asection bfd_und_section;
 464 .#define bfd_und_section_ptr ((asection *) &bfd_und_section)
 465 .#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)
 466 .    {* Pointer to the common section *}
 467 .extern const asection bfd_com_section;
 468 .#define bfd_com_section_ptr ((asection *) &bfd_com_section)
 469 .    {* Pointer to the indirect section *}
 470 .extern const asection bfd_ind_section;
 471 .#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)
 472 .#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)
 473 .
 474 .extern const struct symbol_cache_entry * const bfd_abs_symbol;
 475 .extern const struct symbol_cache_entry * const bfd_com_symbol;
 476 .extern const struct symbol_cache_entry * const bfd_und_symbol;
 477 .extern const struct symbol_cache_entry * const bfd_ind_symbol;
 478 .#define bfd_get_section_size_before_reloc(section) \
 479 .     (section->reloc_done ? (abort(),1): (section)->_raw_size)
 480 .#define bfd_get_section_size_after_reloc(section) \
 481 .     ((section->reloc_done) ? (section)->_cooked_size: (abort(),1))
 482 */
 483
 484 /* These symbols are global, not specific to any BFD.  Therefore, anything
 485    that tries to change them is broken, and should be repaired.  */
 486 static const asymbol global_syms[] =
 487 {
 488  /* the_bfd, name, value, attr, section [, udata] */
 489   {0, BFD_COM_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_com_section},
 490   {0, BFD_UND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_und_section},
 491   {0, BFD_ABS_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_abs_section},
 492   {0, BFD_IND_SECTION_NAME, 0, BSF_SECTION_SYM, (asection *) &bfd_ind_section},
 493 };
 494
 495 #define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
 496   const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
 497   const asection SEC = \
 498     { NAME, 0, 0, FLAGS, 0, 0, 0, 0, 0, 0, 0, 0, 0, (asection *) &SEC, \
 499       0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0, \
 500       (asymbol *) &global_syms[IDX], (asymbol **) &SYM, 0, 0 }
 501
 502 STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
 503              BFD_COM_SECTION_NAME, 0);
 504 STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
 505 STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
 506 STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
 507 #undef STD_SECTION
 508
 509 /*
 510 DOCDD
 511 INODE
 512 section prototypes,  , typedef asection, Sections
 513 SUBSECTION
 514         Section prototypes
 515
 516 These are the functions exported by the section handling part of BFD.
 517 */
 518
 519 /*
 520 FUNCTION
 521         bfd_get_section_by_name
 522
 523 SYNOPSIS
 524         asection *bfd_get_section_by_name(bfd *abfd, CONST char *name);
 525
 526 DESCRIPTION
 527         Run through @var{abfd} and return the one of the
 528         <<asection>>s whose name matches @var{name}, otherwise <<NULL>>.
 529         @xref{Sections}, for more information.
 530
 531         This should only be used in special cases; the normal way to process
 532         all sections of a given name is to use <<bfd_map_over_sections>> and
 533         <<strcmp>> on the name (or better yet, base it on the section flags
 534         or something else) for each section.
 535 */
 536
 537 asection *
 538 bfd_get_section_by_name (abfd, name)
 539      bfd *abfd;
 540      CONST char *name;
 541 {
 542   asection *sect;
 543
 544   for (sect = abfd->sections; sect != NULL; sect = sect->next)
 545     if (!strcmp (sect->name, name))
 546       return sect;
 547   return NULL;
 548 }
 549
 550
 551 /*
 552 FUNCTION
 553         bfd_make_section_old_way
 554
 555 SYNOPSIS
 556         asection *bfd_make_section_old_way(bfd *abfd, CONST char *name);
 557
 558 DESCRIPTION
 559         Create a new empty section called @var{name}
 560         and attach it to the end of the chain of sections for the
 561         BFD @var{abfd}. An attempt to create a section with a name which
 562         is already in use returns its pointer without changing the
 563         section chain.
 564
 565         It has the funny name since this is the way it used to be
 566         before it was rewritten....
 567
 568         Possible errors are:
 569         o <<bfd_error_invalid_operation>> -
 570         If output has already started for this BFD.
 571         o <<bfd_error_no_memory>> -
 572         If memory allocation fails.
 573
 574 */
 575
 576
 577 asection *
 578 bfd_make_section_old_way (abfd, name)
 579      bfd *abfd;
 580      CONST char *name;
 581 {
 582   asection *sec = bfd_get_section_by_name (abfd, name);
 583   if (sec == (asection *) NULL)
 584     {
 585       sec = bfd_make_section (abfd, name);
 586     }
 587   return sec;
 588 }
 589
 590 /*
 591 FUNCTION
 592         bfd_make_section_anyway
 593
 594 SYNOPSIS
 595         asection *bfd_make_section_anyway(bfd *abfd, CONST char *name);
 596
 597 DESCRIPTION
 598    Create a new empty section called @var{name} and attach it to the end of
 599    the chain of sections for @var{abfd}.  Create a new section even if there
 600    is already a section with that name.
 601
 602    Return <<NULL>> and set <<bfd_error>> on error; possible errors are:
 603    o <<bfd_error_invalid_operation>> - If output has already started for @var{abfd}.
 604    o <<bfd_error_no_memory>> - If memory allocation fails.
 605 */
 606
 607 sec_ptr
 608 bfd_make_section_anyway (abfd, name)
 609      bfd *abfd;
 610      CONST char *name;
 611 {
 612   asection *newsect;
 613   asection **prev = &abfd->sections;
 614   asection *sect = abfd->sections;
 615
 616   if (abfd->output_has_begun)
 617     {
 618       bfd_set_error (bfd_error_invalid_operation);
 619       return NULL;
 620     }
 621
 622   while (sect)
 623     {
 624       prev = &sect->next;
 625       sect = sect->next;
 626     }
 627
 628   newsect = (asection *) bfd_zalloc (abfd, sizeof (asection));
 629   if (newsect == NULL)
 630     return NULL;
 631
 632   newsect->name = name;
 633   newsect->index = abfd->section_count++;
 634   newsect->flags = SEC_NO_FLAGS;
 635
 636   newsect->userdata = NULL;
 637   newsect->contents = NULL;
 638   newsect->next = (asection *) NULL;
 639   newsect->relocation = (arelent *) NULL;
 640   newsect->reloc_count = 0;
 641   newsect->line_filepos = 0;
 642   newsect->owner = abfd;
 643
 644   /* Create a symbol whos only job is to point to this section. This is
 645      useful for things like relocs which are relative to the base of a
 646      section.  */
 647   newsect->symbol = bfd_make_empty_symbol (abfd);
 648   if (newsect->symbol == NULL)
 649     return NULL;
 650   newsect->symbol->name = name;
 651   newsect->symbol->value = 0;
 652   newsect->symbol->section = newsect;
 653   newsect->symbol->flags = BSF_SECTION_SYM;
 654
 655   newsect->symbol_ptr_ptr = &newsect->symbol;
 656
 657   if (BFD_SEND (abfd, _new_section_hook, (abfd, newsect)) != true)
 658     {
 659       free (newsect);
 660       return NULL;
 661     }
 662
 663   *prev = newsect;
 664   return newsect;
 665 }
 666
 667 /*
 668 FUNCTION
 669         bfd_make_section
 670
 671 SYNOPSIS
 672         asection *bfd_make_section(bfd *, CONST char *name);
 673
 674 DESCRIPTION
 675    Like <<bfd_make_section_anyway>>, but return <<NULL>> (without calling
 676    bfd_set_error ()) without changing the section chain if there is already a
 677    section named @var{name}.  If there is an error, return <<NULL>> and set
 678    <<bfd_error>>.
 679 */
 680
 681 asection *
 682 bfd_make_section (abfd, name)
 683      bfd *abfd;
 684      CONST char *name;
 685 {
 686   asection *sect = abfd->sections;
 687
 688   if (strcmp (name, BFD_ABS_SECTION_NAME) == 0)
 689     {
 690       return bfd_abs_section_ptr;
 691     }
 692   if (strcmp (name, BFD_COM_SECTION_NAME) == 0)
 693     {
 694       return bfd_com_section_ptr;
 695     }
 696   if (strcmp (name, BFD_UND_SECTION_NAME) == 0)
 697     {
 698       return bfd_und_section_ptr;
 699     }
 700
 701   if (strcmp (name, BFD_IND_SECTION_NAME) == 0)
 702     {
 703       return bfd_ind_section_ptr;
 704     }
 705
 706   while (sect)
 707     {
 708       if (!strcmp (sect->name, name))
 709         return NULL;
 710       sect = sect->next;
 711     }
 712
 713   /* The name is not already used; go ahead and make a new section.  */
 714   return bfd_make_section_anyway (abfd, name);
 715 }
 716
 717
 718 /*
 719 FUNCTION
 720         bfd_set_section_flags
 721
 722 SYNOPSIS
 723         boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags);
 724
 725 DESCRIPTION
 726         Set the attributes of the section @var{sec} in the BFD
 727         @var{abfd} to the value @var{flags}. Return <<true>> on success,
 728         <<false>> on error. Possible error returns are:
 729
 730         o <<bfd_error_invalid_operation>> -
 731         The section cannot have one or more of the attributes
 732         requested. For example, a .bss section in <<a.out>> may not
 733         have the <<SEC_HAS_CONTENTS>> field set.
 734
 735 */
 736
 737 /*ARGSUSED*/
 738 boolean
 739 bfd_set_section_flags (abfd, section, flags)
 740      bfd *abfd;
 741      sec_ptr section;
 742      flagword flags;
 743 {
 744 #if 0
 745   /* If you try to copy a text section from an input file (where it
 746      has the SEC_CODE flag set) to an output file, this loses big if
 747      the bfd_applicable_section_flags (abfd) doesn't have the SEC_CODE
 748      set - which it doesn't, at least not for a.out.  FIXME */
 749
 750   if ((flags & bfd_applicable_section_flags (abfd)) != flags)
 751     {
 752       bfd_set_error (bfd_error_invalid_operation);
 753       return false;
 754     }
 755 #endif
 756
 757   section->flags = flags;
 758   return true;
 759 }
 760
 761
 762 /*
 763 FUNCTION
 764         bfd_map_over_sections
 765
 766 SYNOPSIS
 767         void bfd_map_over_sections(bfd *abfd,
 768                                    void (*func)(bfd *abfd,
 769                                                 asection *sect,
 770                                                 PTR obj),
 771                                    PTR obj);
 772
 773 DESCRIPTION
 774         Call the provided function @var{func} for each section
 775         attached to the BFD @var{abfd}, passing @var{obj} as an
 776         argument. The function will be called as if by
 777
 778 |       func(abfd, the_section, obj);
 779
 780         This is the prefered method for iterating over sections; an
 781         alternative would be to use a loop:
 782
 783 |          section *p;
 784 |          for (p = abfd->sections; p != NULL; p = p->next)
 785 |             func(abfd, p, ...)
 786
 787
 788 */
 789
 790 /*VARARGS2*/
 791 void
 792 bfd_map_over_sections (abfd, operation, user_storage)
 793      bfd *abfd;
 794      void (*operation) PARAMS ((bfd * abfd, asection * sect, PTR obj));
 795      PTR user_storage;
 796 {
 797   asection *sect;
 798   unsigned int i = 0;
 799
 800   for (sect = abfd->sections; sect != NULL; i++, sect = sect->next)
 801     (*operation) (abfd, sect, user_storage);
 802
 803   if (i != abfd->section_count) /* Debugging */
 804     abort ();
 805 }
 806
 807
 808 /*
 809 FUNCTION
 810         bfd_set_section_size
 811
 812 SYNOPSIS
 813         boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val);
 814
 815 DESCRIPTION
 816         Set @var{sec} to the size @var{val}. If the operation is
 817         ok, then <<true>> is returned, else <<false>>.
 818
 819         Possible error returns:
 820         o <<bfd_error_invalid_operation>> -
 821         Writing has started to the BFD, so setting the size is invalid.
 822
 823 */
 824
 825 boolean
 826 bfd_set_section_size (abfd, ptr, val)
 827      bfd *abfd;
 828      sec_ptr ptr;
 829      bfd_size_type val;
 830 {
 831   /* Once you've started writing to any section you cannot create or change
 832      the size of any others. */
 833
 834   if (abfd->output_has_begun)
 835     {
 836       bfd_set_error (bfd_error_invalid_operation);
 837       return false;
 838     }
 839
 840   ptr->_cooked_size = val;
 841   ptr->_raw_size = val;
 842
 843   return true;
 844 }
 845
 846 /*
 847 FUNCTION
 848         bfd_set_section_contents
 849
 850 SYNOPSIS
 851         boolean bfd_set_section_contents
 852          (bfd *abfd,
 853          asection *section,
 854          PTR data,
 855          file_ptr offset,
 856          bfd_size_type count);
 857
 858
 859 DESCRIPTION
 860         Sets the contents of the section @var{section} in BFD
 861         @var{abfd} to the data starting in memory at @var{data}. The
 862         data is written to the output section starting at offset
 863         @var{offset} for @var{count} bytes.
 864
 865
 866
 867         Normally <<true>> is returned, else <<false>>. Possible error
 868         returns are:
 869         o <<bfd_error_no_contents>> -
 870         The output section does not have the <<SEC_HAS_CONTENTS>>
 871         attribute, so nothing can be written to it.
 872         o and some more too
 873
 874         This routine is front end to the back end function
 875         <<_bfd_set_section_contents>>.
 876
 877
 878 */
 879
 880 #define bfd_get_section_size_now(abfd,sec) \
 881 (sec->reloc_done \
 882  ? bfd_get_section_size_after_reloc (sec) \
 883  : bfd_get_section_size_before_reloc (sec))
 884
 885 boolean
 886 bfd_set_section_contents (abfd, section, location, offset, count)
 887      bfd *abfd;
 888      sec_ptr section;
 889      PTR location;
 890      file_ptr offset;
 891      bfd_size_type count;
 892 {
 893   bfd_size_type sz;
 894
 895   if (!(bfd_get_section_flags (abfd, section) & SEC_HAS_CONTENTS))
 896     {
 897       bfd_set_error (bfd_error_no_contents);
 898       return (false);
 899     }
 900
 901   if (offset < 0)
 902     {
 903     bad_val:
 904       bfd_set_error (bfd_error_bad_value);
 905       return false;
 906     }
 907   sz = bfd_get_section_size_now (abfd, section);
 908   if ((bfd_size_type) offset > sz
 909       || count > sz
 910       || offset + count > sz)
 911     goto bad_val;
 912
 913   switch (abfd->direction)
 914     {
 915     case read_direction:
 916     case no_direction:
 917       bfd_set_error (bfd_error_invalid_operation);
 918       return false;
 919
 920     case write_direction:
 921       break;
 922
 923     case both_direction:
 924       /* File is opened for update. `output_has_begun' some time ago when
 925            the file was created.  Do not recompute sections sizes or alignments
 926            in _bfd_set_section_content.  */
 927       abfd->output_has_begun = true;
 928       break;
 929     }
 930
 931   if (BFD_SEND (abfd, _bfd_set_section_contents,
 932                 (abfd, section, location, offset, count)))
 933     {
 934       abfd->output_has_begun = true;
 935       return true;
 936     }
 937
 938   return false;
 939 }
 940
 941 /*
 942 FUNCTION
 943         bfd_get_section_contents
 944
 945 SYNOPSIS
 946         boolean bfd_get_section_contents
 947         (bfd *abfd, asection *section, PTR location,
 948          file_ptr offset, bfd_size_type count);
 949
 950 DESCRIPTION
 951         Read data from @var{section} in BFD @var{abfd}
 952         into memory starting at @var{location}. The data is read at an
 953         offset of @var{offset} from the start of the input section,
 954         and is read for @var{count} bytes.
 955
 956         If the contents of a constructor with the <<SEC_CONSTRUCTOR>>
 957         flag set are requested or if the section does not have the
 958         <<SEC_HAS_CONTENTS>> flag set, then the @var{location} is filled
 959         with zeroes. If no errors occur, <<true>> is returned, else
 960         <<false>>.
 961
 962
 963
 964 */
 965 boolean
 966 bfd_get_section_contents (abfd, section, location, offset, count)
 967      bfd *abfd;
 968      sec_ptr section;
 969      PTR location;
 970      file_ptr offset;
 971      bfd_size_type count;
 972 {
 973   bfd_size_type sz;
 974
 975   if (section->flags & SEC_CONSTRUCTOR)
 976     {
 977       memset (location, 0, (unsigned) count);
 978       return true;
 979     }
 980
 981   if (offset < 0)
 982     {
 983     bad_val:
 984       bfd_set_error (bfd_error_bad_value);
 985       return false;
 986     }
 987   /* Even if reloc_done is true, this function reads unrelocated
 988      contents, so we want the raw size.  */
 989   sz = section->_raw_size;
 990   if ((bfd_size_type) offset > sz || count > sz || offset + count > sz)
 991     goto bad_val;
 992
 993   if (count == 0)
 994     /* Don't bother.  */
 995     return true;
 996
 997   if ((section->flags & SEC_HAS_CONTENTS) == 0)
 998     {
 999       memset (location, 0, (unsigned) count);
1000       return true;
1001     }
1002
1003   if ((section->flags & SEC_IN_MEMORY) != 0)
1004     {
1005       memcpy (location, section->contents + offset, (size_t) count);
1006       return true;
1007     }
1008
1009   return BFD_SEND (abfd, _bfd_get_section_contents,
1010                    (abfd, section, location, offset, count));
1011 }
1012
1013 /*
1014 FUNCTION
1015         bfd_copy_private_section_data
1016
1017 SYNOPSIS
1018         boolean bfd_copy_private_section_data(bfd *ibfd, asection *isec, bfd *obfd, asection *osec);
1019
1020 DESCRIPTION
1021         Copy private section information from @var{isec} in the BFD
1022         @var{ibfd} to the section @var{osec} in the BFD @var{obfd}.
1023         Return <<true>> on success, <<false>> on error.  Possible error
1024         returns are:
1025
1026         o <<bfd_error_no_memory>> -
1027         Not enough memory exists to create private data for @var{osec}.
1028
1029 .#define bfd_copy_private_section_data(ibfd, isection, obfd, osection) \
1030 .     BFD_SEND (obfd, _bfd_copy_private_section_data, \
1031 .               (ibfd, isection, obfd, osection))
1032 */
1033
1034 /*
1035 FUNCTION
1036         _bfd_strip_section_from_output
1037
1038 SYNOPSIS
1039         void _bfd_strip_section_from_output
1040         (asection *section);
1041
1042 DESCRIPTION
1043         Remove @var{section} from the output.  If the output section becomes
1044         empty, remove it from the output bfd.
1045 */
1046 void
1047 _bfd_strip_section_from_output (s)
1048      asection *s;
1049 {
1050   asection **spp, *os;
1051   struct bfd_link_order *p, *pp;
1052
1053   /* Excise the input section from the link order.  */
1054   os = s->output_section;
1055   for (p = os->link_order_head, pp = NULL; p != NULL; pp = p, p = p->next)
1056     if (p->type == bfd_indirect_link_order
1057         && p->u.indirect.section == s)
1058       {
1059         if (pp)
1060           pp->next = p->next;
1061         else
1062           os->link_order_head = p->next;
1063         if (!p->next)
1064           os->link_order_tail = pp;
1065         break;
1066       }
1067
1068   /* If the output section is empty, remove it too.  */
1069   if (!os->link_order_head)
1070     {
1071       for (spp = &os->owner->sections; *spp; spp = &(*spp)->next)
1072         if (*spp == os)
1073           {
1074             *spp = os->next;
1075             os->owner->section_count--;
1076             break;
1077           }
1078     }
1079 }