include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2015 Free Software Foundation, Inc.
   3    Written by Steve Chamberlain and Ian Lance Taylor, 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 3 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., 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22 #ifndef BFDLINK_H
  23 #define BFDLINK_H
  24
  25 /* Which symbols to strip during a link.  */
  26 enum bfd_link_strip
  27 {
  28   strip_none,           /* Don't strip any symbols.  */
  29   strip_debugger,       /* Strip debugging symbols.  */
  30   strip_some,           /* keep_hash is the list of symbols to keep.  */
  31   strip_all             /* Strip all symbols.  */
  32 };
  33
  34 /* Which local symbols to discard during a link.  This is irrelevant
  35    if strip_all is used.  */
  36 enum bfd_link_discard
  37 {
  38   discard_sec_merge,    /* Discard local temporary symbols in SEC_MERGE
  39                            sections.  */
  40   discard_none,         /* Don't discard any locals.  */
  41   discard_l,            /* Discard local temporary symbols.  */
  42   discard_all           /* Discard all locals.  */
  43 };
  44
  45 /* Describes the type of hash table entry structure being used.
  46    Different hash table structure have different fields and so
  47    support different linking features.  */
  48 enum bfd_link_hash_table_type
  49   {
  50     bfd_link_generic_hash_table,
  51     bfd_link_elf_hash_table
  52   };
  53 \f
  54 /* These are the possible types of an entry in the BFD link hash
  55    table.  */
  56
  57 enum bfd_link_hash_type
  58 {
  59   bfd_link_hash_new,            /* Symbol is new.  */
  60   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  61   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  62   bfd_link_hash_defined,        /* Symbol is defined.  */
  63   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  64   bfd_link_hash_common,         /* Symbol is common.  */
  65   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  66   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  67 };
  68
  69 enum bfd_link_common_skip_ar_symbols
  70 {
  71   bfd_link_common_skip_none,
  72   bfd_link_common_skip_text,
  73   bfd_link_common_skip_data,
  74   bfd_link_common_skip_all
  75 };
  76
  77 struct bfd_link_hash_common_entry
  78   {
  79     unsigned int alignment_power;       /* Alignment.  */
  80     asection *section;          /* Symbol section.  */
  81   };
  82
  83 /* The linking routines use a hash table which uses this structure for
  84    its elements.  */
  85
  86 struct bfd_link_hash_entry
  87 {
  88   /* Base hash table entry structure.  */
  89   struct bfd_hash_entry root;
  90
  91   /* Type of this entry.  */
  92   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
  93
  94   /* Symbol is referenced in a normal object file, as distict from a LTO
  95      IR object file.  */
  96   unsigned int non_ir_ref : 1;
  97
  98   /* Symbol is a built-in define.  These will be overridden by PROVIDE
  99      in a linker script.  */
 100   unsigned int linker_def : 1;
 101
 102   /* A union of information depending upon the type.  */
 103   union
 104     {
 105       /* Nothing is kept for bfd_hash_new.  */
 106       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 107       struct
 108         {
 109           /* Undefined and common symbols are kept in a linked list through
 110              this field.  This field is present in all of the union element
 111              so that we don't need to remove entries from the list when we
 112              change their type.  Removing entries would either require the
 113              list to be doubly linked, which would waste more memory, or
 114              require a traversal.  When an undefined or common symbol is
 115              created, it should be added to this list, the head of which is in
 116              the link hash table itself.  As symbols are defined, they need
 117              not be removed from the list; anything which reads the list must
 118              doublecheck the symbol type.
 119
 120              Weak symbols are not kept on this list.
 121
 122              Defined and defweak symbols use this field as a reference marker.
 123              If the field is not NULL, or this structure is the tail of the
 124              undefined symbol list, the symbol has been referenced.  If the
 125              symbol is undefined and becomes defined, this field will
 126              automatically be non-NULL since the symbol will have been on the
 127              undefined symbol list.  */
 128           struct bfd_link_hash_entry *next;
 129           bfd *abfd;            /* BFD symbol was found in.  */
 130         } undef;
 131       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 132       struct
 133         {
 134           struct bfd_link_hash_entry *next;
 135           asection *section;    /* Symbol section.  */
 136           bfd_vma value;        /* Symbol value.  */
 137         } def;
 138       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 139       struct
 140         {
 141           struct bfd_link_hash_entry *next;
 142           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 143           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 144         } i;
 145       /* bfd_link_hash_common.  */
 146       struct
 147         {
 148           struct bfd_link_hash_entry *next;
 149           /* The linker needs to know three things about common
 150              symbols: the size, the alignment, and the section in
 151              which the symbol should be placed.  We store the size
 152              here, and we allocate a small structure to hold the
 153              section and the alignment.  The alignment is stored as a
 154              power of two.  We don't store all the information
 155              directly because we don't want to increase the size of
 156              the union; this structure is a major space user in the
 157              linker.  */
 158           struct bfd_link_hash_common_entry *p;
 159           bfd_size_type size;   /* Common symbol size.  */
 160         } c;
 161     } u;
 162 };
 163
 164 /* This is the link hash table.  It is a derived class of
 165    bfd_hash_table.  */
 166
 167 struct bfd_link_hash_table
 168 {
 169   /* The hash table itself.  */
 170   struct bfd_hash_table table;
 171   /* A linked list of undefined and common symbols, linked through the
 172      next field in the bfd_link_hash_entry structure.  */
 173   struct bfd_link_hash_entry *undefs;
 174   /* Entries are added to the tail of the undefs list.  */
 175   struct bfd_link_hash_entry *undefs_tail;
 176   /* Function to free the hash table on closing BFD.  */
 177   void (*hash_table_free) (bfd *);
 178   /* The type of the link hash table.  */
 179   enum bfd_link_hash_table_type type;
 180 };
 181
 182 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 183    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 184    the real symbol.  */
 185 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 186   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 187    bfd_boolean copy, bfd_boolean follow);
 188
 189 /* Look up an entry in the main linker hash table if the symbol might
 190    be wrapped.  This should only be used for references to an
 191    undefined symbol, not for definitions of a symbol.  */
 192
 193 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 194   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 195    bfd_boolean, bfd_boolean);
 196
 197 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 198    and the remainder is found in wrap_hash, return the real symbol.  */
 199
 200 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 201   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 202
 203 /* Traverse a link hash table.  */
 204 extern void bfd_link_hash_traverse
 205   (struct bfd_link_hash_table *,
 206     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 207     void *);
 208
 209 /* Add an entry to the undefs list.  */
 210 extern void bfd_link_add_undef
 211   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 212
 213 /* Remove symbols from the undefs list that don't belong there.  */
 214 extern void bfd_link_repair_undef_list
 215   (struct bfd_link_hash_table *table);
 216
 217 /* Read symbols and cache symbol pointer array in outsymbols.  */
 218 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 219
 220 struct bfd_sym_chain
 221 {
 222   struct bfd_sym_chain *next;
 223   const char *name;
 224 };
 225 \f
 226 /* How to handle unresolved symbols.
 227    There are four possibilities which are enumerated below:  */
 228 enum report_method
 229 {
 230   /* This is the initial value when then link_info structure is created.
 231      It allows the various stages of the linker to determine whether they
 232      allowed to set the value.  */
 233   RM_NOT_YET_SET = 0,
 234   RM_IGNORE,
 235   RM_GENERATE_WARNING,
 236   RM_GENERATE_ERROR
 237 };
 238
 239 typedef enum {with_flags, without_flags} flag_type;
 240
 241 /* A section flag list.  */
 242 struct flag_info_list
 243 {
 244   flag_type with;
 245   const char *name;
 246   bfd_boolean valid;
 247   struct flag_info_list *next;
 248 };
 249
 250 /* Section flag info.  */
 251 struct flag_info
 252 {
 253   flagword only_with_flags;
 254   flagword not_with_flags;
 255   struct flag_info_list *flag_list;
 256   bfd_boolean flags_initialized;
 257 };
 258
 259 struct bfd_elf_dynamic_list;
 260 struct bfd_elf_version_tree;
 261
 262 /* Types of output.  */
 263
 264 enum output_type
 265 {
 266   type_executable = 0,
 267   type_dll,
 268   type_relocatable
 269 };
 270
 271 #define bfd_link_executable(info)  ((info)->type == type_executable)
 272 #define bfd_link_dll(info)         ((info)->type == type_dll)
 273 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 274 #define bfd_link_pic(info)         (info)->pic
 275 #define bfd_link_pie(info)         (bfd_link_executable (info) \
 276                                     && bfd_link_pic (info))
 277 #define bfd_link_pde(info)         (bfd_link_executable (info) \
 278                                     && !bfd_link_pic (info))
 279
 280 /* This structure holds all the information needed to communicate
 281    between BFD and the linker when doing a link.  */
 282
 283 struct bfd_link_info
 284 {
 285   /* Output type.  */
 286   ENUM_BITFIELD (output_type) type : 2;
 287
 288   /* TRUE if BFD should generate a position independent object.  */
 289   unsigned int pic : 1;
 290
 291   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 292   unsigned int symbolic: 1;
 293
 294   /* TRUE if executable should not contain copy relocs.
 295      Setting this true may result in a non-sharable text segment.  */
 296   unsigned int nocopyreloc: 1;
 297
 298   /* TRUE if BFD should export all symbols in the dynamic symbol table
 299      of an executable, rather than only those used.  */
 300   unsigned int export_dynamic: 1;
 301
 302   /* TRUE if a default symbol version should be created and used for
 303      exported symbols.  */
 304   unsigned int create_default_symver: 1;
 305
 306   /* TRUE if unreferenced sections should be removed.  */
 307   unsigned int gc_sections: 1;
 308
 309   /* TRUE if every symbol should be reported back via the notice
 310      callback.  */
 311   unsigned int notice_all: 1;
 312
 313   /* TRUE if the LTO plugin is active.  */
 314   unsigned int lto_plugin_active: 1;
 315
 316   /* TRUE if global symbols in discarded sections should be stripped.  */
 317   unsigned int strip_discarded: 1;
 318
 319   /* TRUE if all data symbols should be dynamic.  */
 320   unsigned int dynamic_data: 1;
 321
 322   /* Which symbols to strip.  */
 323   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 324
 325   /* Which local symbols to discard.  */
 326   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 327
 328   /* Criteria for skipping symbols when determining
 329      whether to include an object from an archive. */
 330   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 331
 332   /* What to do with unresolved symbols in an object file.
 333      When producing executables the default is GENERATE_ERROR.
 334      When producing shared libraries the default is IGNORE.  The
 335      assumption with shared libraries is that the reference will be
 336      resolved at load/execution time.  */
 337   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 338
 339   /* What to do with unresolved symbols in a shared library.
 340      The same defaults apply.  */
 341   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 342
 343   /* TRUE if shared objects should be linked directly, not shared.  */
 344   unsigned int static_link: 1;
 345
 346   /* TRUE if symbols should be retained in memory, FALSE if they
 347      should be freed and reread.  */
 348   unsigned int keep_memory: 1;
 349
 350   /* TRUE if BFD should generate relocation information in the final
 351      executable.  */
 352   unsigned int emitrelocations: 1;
 353
 354   /* TRUE if PT_GNU_RELRO segment should be created.  */
 355   unsigned int relro: 1;
 356
 357   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 358      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 359   unsigned int eh_frame_hdr_type: 2;
 360
 361   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 362   unsigned int warn_shared_textrel: 1;
 363
 364   /* TRUE if we should error when adding a DT_TEXTREL.  */
 365   unsigned int error_textrel: 1;
 366
 367   /* TRUE if .hash section should be created.  */
 368   unsigned int emit_hash: 1;
 369
 370   /* TRUE if .gnu.hash section should be created.  */
 371   unsigned int emit_gnu_hash: 1;
 372
 373   /* If TRUE reduce memory overheads, at the expense of speed. This will
 374      cause map file generation to use an O(N^2) algorithm and disable
 375      caching ELF symbol buffer.  */
 376   unsigned int reduce_memory_overheads: 1;
 377
 378   /* TRUE if the output file should be in a traditional format.  This
 379      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 380      on the output file, but may be checked when reading the input
 381      files.  */
 382   unsigned int traditional_format: 1;
 383
 384   /* TRUE if non-PLT relocs should be merged into one reloc section
 385      and sorted so that relocs against the same symbol come together.  */
 386   unsigned int combreloc: 1;
 387
 388   /* TRUE if a default symbol version should be created and used for
 389      imported symbols.  */
 390   unsigned int default_imported_symver: 1;
 391
 392   /* TRUE if the new ELF dynamic tags are enabled. */
 393   unsigned int new_dtags: 1;
 394
 395   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 396      linker created sections, TRUE if it should be omitted.  */
 397   unsigned int no_ld_generated_unwind_info: 1;
 398
 399   /* TRUE if BFD should generate a "task linked" object file,
 400      similar to relocatable but also with globals converted to
 401      statics.  */
 402   unsigned int task_link: 1;
 403
 404   /* TRUE if ok to have multiple definition.  */
 405   unsigned int allow_multiple_definition: 1;
 406
 407   /* TRUE if ok to have version with no definition.  */
 408   unsigned int allow_undefined_version: 1;
 409
 410   /* TRUE if some symbols have to be dynamic, controlled by
 411      --dynamic-list command line options.  */
 412   unsigned int dynamic: 1;
 413
 414   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 415      flags.  */
 416   unsigned int execstack: 1;
 417
 418   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 419      flags.  */
 420   unsigned int noexecstack: 1;
 421
 422   /* TRUE if we want to produced optimized output files.  This might
 423      need much more time and therefore must be explicitly selected.  */
 424   unsigned int optimize: 1;
 425
 426   /* TRUE if user should be informed of removed unreferenced sections.  */
 427   unsigned int print_gc_sections: 1;
 428
 429   /* TRUE if we should warn alternate ELF machine code.  */
 430   unsigned int warn_alternate_em: 1;
 431
 432   /* TRUE if the linker script contained an explicit PHDRS command.  */
 433   unsigned int user_phdrs: 1;
 434
 435   /* TRUE if BND prefix in PLT entries is always generated.  */
 436   unsigned int bndplt: 1;
 437
 438   /* Char that may appear as the first char of a symbol, but should be
 439      skipped (like symbol_leading_char) when looking up symbols in
 440      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 441   char wrap_char;
 442
 443   /* Separator between archive and filename in linker script filespecs.  */
 444   char path_separator;
 445
 446   /* Compress DWARF debug sections.  */
 447   enum compressed_debug_section_type compress_debug;
 448
 449   /* Default stack size.  Zero means default (often zero itself), -1
 450      means explicitly zero-sized.  */
 451   bfd_signed_vma stacksize;
 452
 453   /* Enable or disable target specific optimizations.
 454
 455      Not all targets have optimizations to enable.
 456
 457      Normally these optimizations are disabled by default but some targets
 458      prefer to enable them by default.  So this field is a tri-state variable.
 459      The values are:
 460
 461      zero: Enable the optimizations (either from --relax being specified on
 462        the command line or the backend's before_allocation emulation function.
 463
 464      positive: The user has requested that these optimizations be disabled.
 465        (Via the --no-relax command line option).
 466
 467      negative: The optimizations are disabled.  (Set when initializing the
 468        args_type structure in ldmain.c:main.  */
 469   signed int disable_target_specific_optimizations;
 470
 471   /* Function callbacks.  */
 472   const struct bfd_link_callbacks *callbacks;
 473
 474   /* Hash table handled by BFD.  */
 475   struct bfd_link_hash_table *hash;
 476
 477   /* Hash table of symbols to keep.  This is NULL unless strip is
 478      strip_some.  */
 479   struct bfd_hash_table *keep_hash;
 480
 481   /* Hash table of symbols to report back via the notice callback.  If
 482      this is NULL, and notice_all is FALSE, then no symbols are
 483      reported back.  */
 484   struct bfd_hash_table *notice_hash;
 485
 486   /* Hash table of symbols which are being wrapped (the --wrap linker
 487      option).  If this is NULL, no symbols are being wrapped.  */
 488   struct bfd_hash_table *wrap_hash;
 489
 490   /* Hash table of symbols which may be left unresolved during
 491      a link.  If this is NULL, no symbols can be left unresolved.  */
 492   struct bfd_hash_table *ignore_hash;
 493
 494   /* The output BFD.  */
 495   bfd *output_bfd;
 496
 497   /* The list of input BFD's involved in the link.  These are chained
 498      together via the link.next field.  */
 499   bfd *input_bfds;
 500   bfd **input_bfds_tail;
 501
 502   /* If a symbol should be created for each input BFD, this is section
 503      where those symbols should be placed.  It must be a section in
 504      the output BFD.  It may be NULL, in which case no such symbols
 505      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 506      linker command language.  */
 507   asection *create_object_symbols_section;
 508
 509   /* List of global symbol names that are starting points for marking
 510      sections against garbage collection.  */
 511   struct bfd_sym_chain *gc_sym_list;
 512
 513   /* If a base output file is wanted, then this points to it */
 514   void *base_file;
 515
 516   /* The function to call when the executable or shared object is
 517      loaded.  */
 518   const char *init_function;
 519
 520   /* The function to call when the executable or shared object is
 521      unloaded.  */
 522   const char *fini_function;
 523
 524   /* Number of relaxation passes.  Usually only one relaxation pass
 525      is needed.  But a backend can have as many relaxation passes as
 526      necessary.  During bfd_relax_section call, it is set to the
 527      current pass, starting from 0.  */
 528   int relax_pass;
 529
 530   /* Number of relaxation trips.  This number is incremented every
 531      time the relaxation pass is restarted due to a previous
 532      relaxation returning true in *AGAIN.  */
 533   int relax_trip;
 534
 535   /* > 0 to treat protected data defined in the shared library as
 536      reference external.  0 to treat it as internal.  -1 to let
 537      backend to decide.  */
 538   int extern_protected_data;
 539
 540   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 541      should be generated/linked against.  Set to 1 if this feature
 542      is explicitly requested by the user, -1 if enabled by default.  */
 543   int pei386_auto_import;
 544
 545   /* Non-zero if runtime relocs for DATA items with non-zero addends
 546      in pei386 DLLs should be generated.  Set to 1 if this feature
 547      is explicitly requested by the user, -1 if enabled by default.  */
 548   int pei386_runtime_pseudo_reloc;
 549
 550   /* How many spare .dynamic DT_NULL entries should be added?  */
 551   unsigned int spare_dynamic_tags;
 552
 553   /* May be used to set DT_FLAGS for ELF. */
 554   bfd_vma flags;
 555
 556   /* May be used to set DT_FLAGS_1 for ELF. */
 557   bfd_vma flags_1;
 558
 559   /* Start and end of RELRO region.  */
 560   bfd_vma relro_start, relro_end;
 561
 562   /* List of symbols should be dynamic.  */
 563   struct bfd_elf_dynamic_list *dynamic_list;
 564
 565   /* The version information.  */
 566   struct bfd_elf_version_tree *version_info;
 567 };
 568
 569 /* This structures holds a set of callback functions.  These are called
 570    by the BFD linker routines.  Except for the info functions, the first
 571    argument to each callback function is the bfd_link_info structure
 572    being used and each function returns a boolean value.  If the
 573    function returns FALSE, then the BFD function which called it should
 574    return with a failure indication.  */
 575
 576 struct bfd_link_callbacks
 577 {
 578   /* A function which is called when an object is added from an
 579      archive.  ABFD is the archive element being added.  NAME is the
 580      name of the symbol which caused the archive element to be pulled
 581      in.  This function may set *SUBSBFD to point to an alternative
 582      BFD from which symbols should in fact be added in place of the
 583      original BFD's symbols.  */
 584   bfd_boolean (*add_archive_element)
 585     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 586   /* A function which is called when a symbol is found with multiple
 587      definitions.  H is the symbol which is defined multiple times.
 588      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 589      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 590   bfd_boolean (*multiple_definition)
 591     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 592      bfd *nbfd, asection *nsec, bfd_vma nval);
 593   /* A function which is called when a common symbol is defined
 594      multiple times.  H is the symbol appearing multiple times.
 595      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 596      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 597      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 598      is the size of the new symbol.  */
 599   bfd_boolean (*multiple_common)
 600     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 601      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 602   /* A function which is called to add a symbol to a set.  ENTRY is
 603      the link hash table entry for the set itself (e.g.,
 604      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 605      the set when generating a relocatable file, and is also used to
 606      get the size of the entry when generating an executable file.
 607      ABFD, SEC and VALUE identify the value to add to the set.  */
 608   bfd_boolean (*add_to_set)
 609     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 610      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 611   /* A function which is called when the name of a g++ constructor or
 612      destructor is found.  This is only called by some object file
 613      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 614      destructor.  This will use BFD_RELOC_CTOR when generating a
 615      relocatable file.  NAME is the name of the symbol found.  ABFD,
 616      SECTION and VALUE are the value of the symbol.  */
 617   bfd_boolean (*constructor)
 618     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 619      bfd *abfd, asection *sec, bfd_vma value);
 620   /* A function which is called to issue a linker warning.  For
 621      example, this is called when there is a reference to a warning
 622      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 623      of the symbol which triggered the warning; it may be NULL if
 624      there is none.  ABFD, SECTION and ADDRESS identify the location
 625      which trigerred the warning; either ABFD or SECTION or both may
 626      be NULL if the location is not known.  */
 627   bfd_boolean (*warning)
 628     (struct bfd_link_info *, const char *warning, const char *symbol,
 629      bfd *abfd, asection *section, bfd_vma address);
 630   /* A function which is called when a relocation is attempted against
 631      an undefined symbol.  NAME is the symbol which is undefined.
 632      ABFD, SECTION and ADDRESS identify the location from which the
 633      reference is made. IS_FATAL indicates whether an undefined symbol is
 634      a fatal error or not. In some cases SECTION may be NULL.  */
 635   bfd_boolean (*undefined_symbol)
 636     (struct bfd_link_info *, const char *name, bfd *abfd,
 637      asection *section, bfd_vma address, bfd_boolean is_fatal);
 638   /* A function which is called when a reloc overflow occurs. ENTRY is
 639      the link hash table entry for the symbol the reloc is against.
 640      NAME is the name of the local symbol or section the reloc is
 641      against, RELOC_NAME is the name of the relocation, and ADDEND is
 642      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 643      location at which the overflow occurs; if this is the result of a
 644      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 645      ABFD will be NULL.  */
 646   bfd_boolean (*reloc_overflow)
 647     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 648      const char *name, const char *reloc_name, bfd_vma addend,
 649      bfd *abfd, asection *section, bfd_vma address);
 650   /* A function which is called when a dangerous reloc is performed.
 651      MESSAGE is an appropriate message.
 652      ABFD, SECTION and ADDRESS identify the location at which the
 653      problem occurred; if this is the result of a
 654      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 655      ABFD will be NULL.  */
 656   bfd_boolean (*reloc_dangerous)
 657     (struct bfd_link_info *, const char *message,
 658      bfd *abfd, asection *section, bfd_vma address);
 659   /* A function which is called when a reloc is found to be attached
 660      to a symbol which is not being written out.  NAME is the name of
 661      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 662      the reloc; if this is the result of a
 663      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 664      ABFD will be NULL.  */
 665   bfd_boolean (*unattached_reloc)
 666     (struct bfd_link_info *, const char *name,
 667      bfd *abfd, asection *section, bfd_vma address);
 668   /* A function which is called when a symbol in notice_hash is
 669      defined or referenced.  H is the symbol, INH the indirect symbol
 670      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 671      the symbol.  If SECTION is bfd_und_section, this is a reference.
 672      FLAGS are the symbol BSF_* flags.  */
 673   bfd_boolean (*notice)
 674     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 675      struct bfd_link_hash_entry *inh,
 676      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 677   /* Error or warning link info message.  */
 678   void (*einfo)
 679     (const char *fmt, ...);
 680   /* General link info message.  */
 681   void (*info)
 682     (const char *fmt, ...);
 683   /* Message to be printed in linker map file.  */
 684   void (*minfo)
 685     (const char *fmt, ...);
 686   /* This callback provides a chance for users of the BFD library to
 687      override its decision about whether to place two adjacent sections
 688      into the same segment.  */
 689   bfd_boolean (*override_segment_assignment)
 690     (struct bfd_link_info *, bfd * abfd,
 691      asection * current_section, asection * previous_section,
 692      bfd_boolean new_segment);
 693 };
 694 \f
 695 /* The linker builds link_order structures which tell the code how to
 696    include input data in the output file.  */
 697
 698 /* These are the types of link_order structures.  */
 699
 700 enum bfd_link_order_type
 701 {
 702   bfd_undefined_link_order,     /* Undefined.  */
 703   bfd_indirect_link_order,      /* Built from a section.  */
 704   bfd_data_link_order,          /* Set to explicit data.  */
 705   bfd_section_reloc_link_order, /* Relocate against a section.  */
 706   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 707 };
 708
 709 /* This is the link_order structure itself.  These form a chain
 710    attached to the output section whose contents they are describing.  */
 711
 712 struct bfd_link_order
 713 {
 714   /* Next link_order in chain.  */
 715   struct bfd_link_order *next;
 716   /* Type of link_order.  */
 717   enum bfd_link_order_type type;
 718   /* Offset within output section.  */
 719   bfd_vma offset;
 720   /* Size within output section.  */
 721   bfd_size_type size;
 722   /* Type specific information.  */
 723   union
 724     {
 725       struct
 726         {
 727           /* Section to include.  If this is used, then
 728              section->output_section must be the section the
 729              link_order is attached to, section->output_offset must
 730              equal the link_order offset field, and section->size
 731              must equal the link_order size field.  Maybe these
 732              restrictions should be relaxed someday.  */
 733           asection *section;
 734         } indirect;
 735       struct
 736         {
 737           /* Size of contents, or zero when contents should be filled by
 738              the architecture-dependent fill function.
 739              A non-zero value allows filling of the output section
 740              with an arbitrary repeated pattern.  */
 741           unsigned int size;
 742           /* Data to put into file.  */
 743           bfd_byte *contents;
 744         } data;
 745       struct
 746         {
 747           /* Description of reloc to generate.  Used for
 748              bfd_section_reloc_link_order and
 749              bfd_symbol_reloc_link_order.  */
 750           struct bfd_link_order_reloc *p;
 751         } reloc;
 752     } u;
 753 };
 754
 755 /* A linker order of type bfd_section_reloc_link_order or
 756    bfd_symbol_reloc_link_order means to create a reloc against a
 757    section or symbol, respectively.  This is used to implement -Ur to
 758    generate relocs for the constructor tables.  The
 759    bfd_link_order_reloc structure describes the reloc that BFD should
 760    create.  It is similar to a arelent, but I didn't use arelent
 761    because the linker does not know anything about most symbols, and
 762    any asymbol structure it creates will be partially meaningless.
 763    This information could logically be in the bfd_link_order struct,
 764    but I didn't want to waste the space since these types of relocs
 765    are relatively rare.  */
 766
 767 struct bfd_link_order_reloc
 768 {
 769   /* Reloc type.  */
 770   bfd_reloc_code_real_type reloc;
 771
 772   union
 773     {
 774       /* For type bfd_section_reloc_link_order, this is the section
 775          the reloc should be against.  This must be a section in the
 776          output BFD, not any of the input BFDs.  */
 777       asection *section;
 778       /* For type bfd_symbol_reloc_link_order, this is the name of the
 779          symbol the reloc should be against.  */
 780       const char *name;
 781     } u;
 782
 783   /* Addend to use.  The object file should contain zero.  The BFD
 784      backend is responsible for filling in the contents of the object
 785      file correctly.  For some object file formats (e.g., COFF) the
 786      addend must be stored into in the object file, and for some
 787      (e.g., SPARC a.out) it is kept in the reloc.  */
 788   bfd_vma addend;
 789 };
 790
 791 /* Allocate a new link_order for a section.  */
 792 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 793
 794 /* These structures are used to describe version information for the
 795    ELF linker.  These structures could be manipulated entirely inside
 796    BFD, but it would be a pain.  Instead, the regular linker sets up
 797    these structures, and then passes them into BFD.  */
 798
 799 /* Glob pattern for a version.  */
 800
 801 struct bfd_elf_version_expr
 802 {
 803   /* Next glob pattern for this version.  */
 804   struct bfd_elf_version_expr *next;
 805   /* Glob pattern.  */
 806   const char *pattern;
 807   /* Set if pattern is not a glob.  */
 808   unsigned int literal : 1;
 809   /* Defined by ".symver".  */
 810   unsigned int symver : 1;
 811   /* Defined by version script.  */
 812   unsigned int script : 1;
 813   /* Pattern type.  */
 814 #define BFD_ELF_VERSION_C_TYPE          1
 815 #define BFD_ELF_VERSION_CXX_TYPE        2
 816 #define BFD_ELF_VERSION_JAVA_TYPE       4
 817   unsigned int mask : 3;
 818 };
 819
 820 struct bfd_elf_version_expr_head
 821 {
 822   /* List of all patterns, both wildcards and non-wildcards.  */
 823   struct bfd_elf_version_expr *list;
 824   /* Hash table for non-wildcards.  */
 825   void *htab;
 826   /* Remaining patterns.  */
 827   struct bfd_elf_version_expr *remaining;
 828   /* What kind of pattern types are present in list (bitmask).  */
 829   unsigned int mask;
 830 };
 831
 832 /* Version dependencies.  */
 833
 834 struct bfd_elf_version_deps
 835 {
 836   /* Next dependency for this version.  */
 837   struct bfd_elf_version_deps *next;
 838   /* The version which this version depends upon.  */
 839   struct bfd_elf_version_tree *version_needed;
 840 };
 841
 842 /* A node in the version tree.  */
 843
 844 struct bfd_elf_version_tree
 845 {
 846   /* Next version.  */
 847   struct bfd_elf_version_tree *next;
 848   /* Name of this version.  */
 849   const char *name;
 850   /* Version number.  */
 851   unsigned int vernum;
 852   /* Regular expressions for global symbols in this version.  */
 853   struct bfd_elf_version_expr_head globals;
 854   /* Regular expressions for local symbols in this version.  */
 855   struct bfd_elf_version_expr_head locals;
 856   /* List of versions which this version depends upon.  */
 857   struct bfd_elf_version_deps *deps;
 858   /* Index of the version name.  This is used within BFD.  */
 859   unsigned int name_indx;
 860   /* Whether this version tree was used.  This is used within BFD.  */
 861   int used;
 862   /* Matching hook.  */
 863   struct bfd_elf_version_expr *(*match)
 864     (struct bfd_elf_version_expr_head *head,
 865      struct bfd_elf_version_expr *prev, const char *sym);
 866 };
 867
 868 struct bfd_elf_dynamic_list
 869 {
 870   struct bfd_elf_version_expr_head head;
 871   struct bfd_elf_version_expr *(*match)
 872     (struct bfd_elf_version_expr_head *head,
 873      struct bfd_elf_version_expr *prev, const char *sym);
 874 };
 875
 876 #endif