include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2018 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 /* Whether to generate ELF common symbols with the STT_COMMON type
  46    during a relocatable link.  */
  47 enum bfd_link_elf_stt_common
  48 {
  49   unchanged,
  50   elf_stt_common,
  51   no_elf_stt_common
  52 };
  53
  54 /* Describes the type of hash table entry structure being used.
  55    Different hash table structure have different fields and so
  56    support different linking features.  */
  57 enum bfd_link_hash_table_type
  58   {
  59     bfd_link_generic_hash_table,
  60     bfd_link_elf_hash_table
  61   };
  62 \f
  63 /* These are the possible types of an entry in the BFD link hash
  64    table.  */
  65
  66 enum bfd_link_hash_type
  67 {
  68   bfd_link_hash_new,            /* Symbol is new.  */
  69   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  70   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  71   bfd_link_hash_defined,        /* Symbol is defined.  */
  72   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  73   bfd_link_hash_common,         /* Symbol is common.  */
  74   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  75   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  76 };
  77
  78 enum bfd_link_common_skip_ar_symbols
  79 {
  80   bfd_link_common_skip_none,
  81   bfd_link_common_skip_text,
  82   bfd_link_common_skip_data,
  83   bfd_link_common_skip_all
  84 };
  85
  86 struct bfd_link_hash_common_entry
  87   {
  88     unsigned int alignment_power;       /* Alignment.  */
  89     asection *section;          /* Symbol section.  */
  90   };
  91
  92 /* The linking routines use a hash table which uses this structure for
  93    its elements.  */
  94
  95 struct bfd_link_hash_entry
  96 {
  97   /* Base hash table entry structure.  */
  98   struct bfd_hash_entry root;
  99
 100   /* Type of this entry.  */
 101   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
 102
 103   /* Symbol is referenced in a normal regular object file,
 104      as distinct from a LTO IR object file.  */
 105   unsigned int non_ir_ref_regular : 1;
 106
 107   /* Symbol is referenced in a normal dynamic object file,
 108      as distinct from a LTO IR object file.  */
 109   unsigned int non_ir_ref_dynamic : 1;
 110
 111   /* Symbol is a built-in define.  These will be overridden by PROVIDE
 112      in a linker script.  */
 113   unsigned int linker_def : 1;
 114
 115   /* Symbol defined in a linker script.  */
 116   unsigned int ldscript_def : 1;
 117
 118   /* A union of information depending upon the type.  */
 119   union
 120     {
 121       /* Nothing is kept for bfd_hash_new.  */
 122       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 123       struct
 124         {
 125           /* Undefined and common symbols are kept in a linked list through
 126              this field.  This field is present in all of the union element
 127              so that we don't need to remove entries from the list when we
 128              change their type.  Removing entries would either require the
 129              list to be doubly linked, which would waste more memory, or
 130              require a traversal.  When an undefined or common symbol is
 131              created, it should be added to this list, the head of which is in
 132              the link hash table itself.  As symbols are defined, they need
 133              not be removed from the list; anything which reads the list must
 134              doublecheck the symbol type.
 135
 136              Weak symbols are not kept on this list.
 137
 138              Defined and defweak symbols use this field as a reference marker.
 139              If the field is not NULL, or this structure is the tail of the
 140              undefined symbol list, the symbol has been referenced.  If the
 141              symbol is undefined and becomes defined, this field will
 142              automatically be non-NULL since the symbol will have been on the
 143              undefined symbol list.  */
 144           struct bfd_link_hash_entry *next;
 145           /* BFD symbol was found in.  */
 146           bfd *abfd;
 147         } undef;
 148       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 149       struct
 150         {
 151           struct bfd_link_hash_entry *next;
 152           /* Symbol section.  */
 153           asection *section;
 154           /* Symbol value.  */
 155           bfd_vma value;
 156         } def;
 157       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 158       struct
 159         {
 160           struct bfd_link_hash_entry *next;
 161           /* Real symbol.  */
 162           struct bfd_link_hash_entry *link;
 163           /* Warning message (bfd_link_hash_warning only).  */
 164           const char *warning;
 165         } i;
 166       /* bfd_link_hash_common.  */
 167       struct
 168         {
 169           struct bfd_link_hash_entry *next;
 170           /* The linker needs to know three things about common
 171              symbols: the size, the alignment, and the section in
 172              which the symbol should be placed.  We store the size
 173              here, and we allocate a small structure to hold the
 174              section and the alignment.  The alignment is stored as a
 175              power of two.  We don't store all the information
 176              directly because we don't want to increase the size of
 177              the union; this structure is a major space user in the
 178              linker.  */
 179           struct bfd_link_hash_common_entry *p;
 180           /* Common symbol size.  */
 181           bfd_size_type size;
 182         } c;
 183     } u;
 184 };
 185
 186 /* This is the link hash table.  It is a derived class of
 187    bfd_hash_table.  */
 188
 189 struct bfd_link_hash_table
 190 {
 191   /* The hash table itself.  */
 192   struct bfd_hash_table table;
 193   /* A linked list of undefined and common symbols, linked through the
 194      next field in the bfd_link_hash_entry structure.  */
 195   struct bfd_link_hash_entry *undefs;
 196   /* Entries are added to the tail of the undefs list.  */
 197   struct bfd_link_hash_entry *undefs_tail;
 198   /* Function to free the hash table on closing BFD.  */
 199   void (*hash_table_free) (bfd *);
 200   /* The type of the link hash table.  */
 201   enum bfd_link_hash_table_type type;
 202 };
 203
 204 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 205    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 206    the real symbol.  */
 207 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 208   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 209    bfd_boolean copy, bfd_boolean follow);
 210
 211 /* Look up an entry in the main linker hash table if the symbol might
 212    be wrapped.  This should only be used for references to an
 213    undefined symbol, not for definitions of a symbol.  */
 214
 215 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 216   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 217    bfd_boolean, bfd_boolean);
 218
 219 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 220    and the remainder is found in wrap_hash, return the real symbol.  */
 221
 222 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 223   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 224
 225 /* Traverse a link hash table.  */
 226 extern void bfd_link_hash_traverse
 227   (struct bfd_link_hash_table *,
 228     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 229     void *);
 230
 231 /* Add an entry to the undefs list.  */
 232 extern void bfd_link_add_undef
 233   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 234
 235 /* Remove symbols from the undefs list that don't belong there.  */
 236 extern void bfd_link_repair_undef_list
 237   (struct bfd_link_hash_table *table);
 238
 239 /* Read symbols and cache symbol pointer array in outsymbols.  */
 240 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 241
 242 /* Check the relocs in the BFD.  Called after all the input
 243    files have been loaded, and garbage collection has tagged
 244    any unneeded sections.  */
 245 extern bfd_boolean bfd_link_check_relocs (bfd *,struct bfd_link_info *);
 246
 247 struct bfd_sym_chain
 248 {
 249   struct bfd_sym_chain *next;
 250   const char *name;
 251 };
 252 \f
 253 /* How to handle unresolved symbols.
 254    There are four possibilities which are enumerated below:  */
 255 enum report_method
 256 {
 257   /* This is the initial value when then link_info structure is created.
 258      It allows the various stages of the linker to determine whether they
 259      allowed to set the value.  */
 260   RM_NOT_YET_SET = 0,
 261   RM_IGNORE,
 262   RM_GENERATE_WARNING,
 263   RM_GENERATE_ERROR
 264 };
 265
 266 typedef enum {with_flags, without_flags} flag_type;
 267
 268 /* A section flag list.  */
 269 struct flag_info_list
 270 {
 271   flag_type with;
 272   const char *name;
 273   bfd_boolean valid;
 274   struct flag_info_list *next;
 275 };
 276
 277 /* Section flag info.  */
 278 struct flag_info
 279 {
 280   flagword only_with_flags;
 281   flagword not_with_flags;
 282   struct flag_info_list *flag_list;
 283   bfd_boolean flags_initialized;
 284 };
 285
 286 struct bfd_elf_dynamic_list;
 287 struct bfd_elf_version_tree;
 288
 289 /* Types of output.  */
 290
 291 enum output_type
 292 {
 293   type_pde,
 294   type_pie,
 295   type_relocatable,
 296   type_dll,
 297 };
 298
 299 #define bfd_link_pde(info)         ((info)->type == type_pde)
 300 #define bfd_link_dll(info)         ((info)->type == type_dll)
 301 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 302 #define bfd_link_pie(info)         ((info)->type == type_pie)
 303 #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
 304 #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
 305
 306 /* This structure holds all the information needed to communicate
 307    between BFD and the linker when doing a link.  */
 308
 309 struct bfd_link_info
 310 {
 311   /* Output type.  */
 312   ENUM_BITFIELD (output_type) type : 2;
 313
 314   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 315   unsigned int symbolic: 1;
 316
 317   /* TRUE if executable should not contain copy relocs.
 318      Setting this true may result in a non-sharable text segment.  */
 319   unsigned int nocopyreloc: 1;
 320
 321   /* TRUE if BFD should export all symbols in the dynamic symbol table
 322      of an executable, rather than only those used.  */
 323   unsigned int export_dynamic: 1;
 324
 325   /* TRUE if a default symbol version should be created and used for
 326      exported symbols.  */
 327   unsigned int create_default_symver: 1;
 328
 329   /* TRUE if unreferenced sections should be removed.  */
 330   unsigned int gc_sections: 1;
 331
 332   /* TRUE if exported symbols should be kept during section gc.  */
 333   unsigned int gc_keep_exported: 1;
 334
 335   /* TRUE if every symbol should be reported back via the notice
 336      callback.  */
 337   unsigned int notice_all: 1;
 338
 339   /* TRUE if the LTO plugin is active.  */
 340   unsigned int lto_plugin_active: 1;
 341
 342   /* TRUE if global symbols in discarded sections should be stripped.  */
 343   unsigned int strip_discarded: 1;
 344
 345   /* TRUE if all data symbols should be dynamic.  */
 346   unsigned int dynamic_data: 1;
 347
 348   /* TRUE if section groups should be resolved.  */
 349   unsigned int resolve_section_groups: 1;
 350
 351   /* Which symbols to strip.  */
 352   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 353
 354   /* Which local symbols to discard.  */
 355   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 356
 357   /* Whether to generate ELF common symbols with the STT_COMMON type.  */
 358   ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
 359
 360   /* Criteria for skipping symbols when determining
 361      whether to include an object from an archive. */
 362   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 363
 364   /* What to do with unresolved symbols in an object file.
 365      When producing executables the default is GENERATE_ERROR.
 366      When producing shared libraries the default is IGNORE.  The
 367      assumption with shared libraries is that the reference will be
 368      resolved at load/execution time.  */
 369   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 370
 371   /* What to do with unresolved symbols in a shared library.
 372      The same defaults apply.  */
 373   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 374
 375   /* TRUE if shared objects should be linked directly, not shared.  */
 376   unsigned int static_link: 1;
 377
 378   /* TRUE if symbols should be retained in memory, FALSE if they
 379      should be freed and reread.  */
 380   unsigned int keep_memory: 1;
 381
 382   /* TRUE if BFD should generate relocation information in the final
 383      executable.  */
 384   unsigned int emitrelocations: 1;
 385
 386   /* TRUE if PT_GNU_RELRO segment should be created.  */
 387   unsigned int relro: 1;
 388
 389   /* TRUE if separate code segment should be created.  */
 390   unsigned int separate_code: 1;
 391
 392   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 393      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 394   unsigned int eh_frame_hdr_type: 2;
 395
 396   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 397   unsigned int warn_shared_textrel: 1;
 398
 399   /* TRUE if we should error when adding a DT_TEXTREL.  */
 400   unsigned int error_textrel: 1;
 401
 402   /* TRUE if .hash section should be created.  */
 403   unsigned int emit_hash: 1;
 404
 405   /* TRUE if .gnu.hash section should be created.  */
 406   unsigned int emit_gnu_hash: 1;
 407
 408   /* If TRUE reduce memory overheads, at the expense of speed. This will
 409      cause map file generation to use an O(N^2) algorithm and disable
 410      caching ELF symbol buffer.  */
 411   unsigned int reduce_memory_overheads: 1;
 412
 413   /* TRUE if the output file should be in a traditional format.  This
 414      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 415      on the output file, but may be checked when reading the input
 416      files.  */
 417   unsigned int traditional_format: 1;
 418
 419   /* TRUE if non-PLT relocs should be merged into one reloc section
 420      and sorted so that relocs against the same symbol come together.  */
 421   unsigned int combreloc: 1;
 422
 423   /* TRUE if a default symbol version should be created and used for
 424      imported symbols.  */
 425   unsigned int default_imported_symver: 1;
 426
 427   /* TRUE if the new ELF dynamic tags are enabled. */
 428   unsigned int new_dtags: 1;
 429
 430   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 431      linker created sections, TRUE if it should be omitted.  */
 432   unsigned int no_ld_generated_unwind_info: 1;
 433
 434   /* TRUE if BFD should generate a "task linked" object file,
 435      similar to relocatable but also with globals converted to
 436      statics.  */
 437   unsigned int task_link: 1;
 438
 439   /* TRUE if ok to have multiple definition.  */
 440   unsigned int allow_multiple_definition: 1;
 441
 442   /* TRUE if ok to have version with no definition.  */
 443   unsigned int allow_undefined_version: 1;
 444
 445   /* TRUE if some symbols have to be dynamic, controlled by
 446      --dynamic-list command line options.  */
 447   unsigned int dynamic: 1;
 448
 449   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 450      flags.  */
 451   unsigned int execstack: 1;
 452
 453   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 454      flags.  */
 455   unsigned int noexecstack: 1;
 456
 457   /* TRUE if we want to produced optimized output files.  This might
 458      need much more time and therefore must be explicitly selected.  */
 459   unsigned int optimize: 1;
 460
 461   /* TRUE if user should be informed of removed unreferenced sections.  */
 462   unsigned int print_gc_sections: 1;
 463
 464   /* TRUE if we should warn alternate ELF machine code.  */
 465   unsigned int warn_alternate_em: 1;
 466
 467   /* TRUE if the linker script contained an explicit PHDRS command.  */
 468   unsigned int user_phdrs: 1;
 469
 470   /* TRUE if we should check relocations after all input files have
 471      been opened.  */
 472   unsigned int check_relocs_after_open_input: 1;
 473
 474   /* TRUE if BND prefix in PLT entries is always generated.  */
 475   unsigned int bndplt: 1;
 476
 477   /* TRUE if IBT-enabled PLT entries should be generated.  */
 478   unsigned int ibtplt: 1;
 479
 480   /* TRUE if GNU_PROPERTY_X86_FEATURE_1_IBT should be generated.  */
 481   unsigned int ibt: 1;
 482
 483   /* TRUE if GNU_PROPERTY_X86_FEATURE_1_SHSTK should be generated.  */
 484   unsigned int shstk: 1;
 485
 486   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 487   unsigned int nointerp: 1;
 488
 489   /* TRUE if we shouldn't check relocation overflow.  */
 490   unsigned int no_reloc_overflow_check: 1;
 491
 492   /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction.  */
 493   unsigned int call_nop_as_suffix : 1;
 494
 495   /* TRUE if common symbols should be treated as undefined.  */
 496   unsigned int inhibit_common_definition : 1;
 497
 498   /* The 1-byte NOP for x86 call instruction.  */
 499   char call_nop_byte;
 500
 501   /* Char that may appear as the first char of a symbol, but should be
 502      skipped (like symbol_leading_char) when looking up symbols in
 503      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 504   char wrap_char;
 505
 506   /* Separator between archive and filename in linker script filespecs.  */
 507   char path_separator;
 508
 509   /* Compress DWARF debug sections.  */
 510   enum compressed_debug_section_type compress_debug;
 511
 512   /* Default stack size.  Zero means default (often zero itself), -1
 513      means explicitly zero-sized.  */
 514   bfd_signed_vma stacksize;
 515
 516   /* Enable or disable target specific optimizations.
 517
 518      Not all targets have optimizations to enable.
 519
 520      Normally these optimizations are disabled by default but some targets
 521      prefer to enable them by default.  So this field is a tri-state variable.
 522      The values are:
 523
 524      zero: Enable the optimizations (either from --relax being specified on
 525        the command line or the backend's before_allocation emulation function.
 526
 527      positive: The user has requested that these optimizations be disabled.
 528        (Via the --no-relax command line option).
 529
 530      negative: The optimizations are disabled.  (Set when initializing the
 531        args_type structure in ldmain.c:main.  */
 532   signed int disable_target_specific_optimizations;
 533
 534   /* Function callbacks.  */
 535   const struct bfd_link_callbacks *callbacks;
 536
 537   /* Hash table handled by BFD.  */
 538   struct bfd_link_hash_table *hash;
 539
 540   /* Hash table of symbols to keep.  This is NULL unless strip is
 541      strip_some.  */
 542   struct bfd_hash_table *keep_hash;
 543
 544   /* Hash table of symbols to report back via the notice callback.  If
 545      this is NULL, and notice_all is FALSE, then no symbols are
 546      reported back.  */
 547   struct bfd_hash_table *notice_hash;
 548
 549   /* Hash table of symbols which are being wrapped (the --wrap linker
 550      option).  If this is NULL, no symbols are being wrapped.  */
 551   struct bfd_hash_table *wrap_hash;
 552
 553   /* Hash table of symbols which may be left unresolved during
 554      a link.  If this is NULL, no symbols can be left unresolved.  */
 555   struct bfd_hash_table *ignore_hash;
 556
 557   /* The output BFD.  */
 558   bfd *output_bfd;
 559
 560   /* The import library generated.  */
 561   bfd *out_implib_bfd;
 562
 563   /* The list of input BFD's involved in the link.  These are chained
 564      together via the link.next field.  */
 565   bfd *input_bfds;
 566   bfd **input_bfds_tail;
 567
 568   /* If a symbol should be created for each input BFD, this is section
 569      where those symbols should be placed.  It must be a section in
 570      the output BFD.  It may be NULL, in which case no such symbols
 571      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 572      linker command language.  */
 573   asection *create_object_symbols_section;
 574
 575   /* List of global symbol names that are starting points for marking
 576      sections against garbage collection.  */
 577   struct bfd_sym_chain *gc_sym_list;
 578
 579   /* If a base output file is wanted, then this points to it */
 580   void *base_file;
 581
 582   /* The function to call when the executable or shared object is
 583      loaded.  */
 584   const char *init_function;
 585
 586   /* The function to call when the executable or shared object is
 587      unloaded.  */
 588   const char *fini_function;
 589
 590   /* Number of relaxation passes.  Usually only one relaxation pass
 591      is needed.  But a backend can have as many relaxation passes as
 592      necessary.  During bfd_relax_section call, it is set to the
 593      current pass, starting from 0.  */
 594   int relax_pass;
 595
 596   /* Number of relaxation trips.  This number is incremented every
 597      time the relaxation pass is restarted due to a previous
 598      relaxation returning true in *AGAIN.  */
 599   int relax_trip;
 600
 601   /* > 0 to treat protected data defined in the shared library as
 602      reference external.  0 to treat it as internal.  -1 to let
 603      backend to decide.  */
 604   int extern_protected_data;
 605
 606   /* 1 to make undefined weak symbols dynamic when building a dynamic
 607      object.  0 to resolve undefined weak symbols to zero.  -1 to let
 608      the backend decide.  */
 609   int dynamic_undefined_weak;
 610
 611   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 612      should be generated/linked against.  Set to 1 if this feature
 613      is explicitly requested by the user, -1 if enabled by default.  */
 614   int pei386_auto_import;
 615
 616   /* Non-zero if runtime relocs for DATA items with non-zero addends
 617      in pei386 DLLs should be generated.  Set to 1 if this feature
 618      is explicitly requested by the user, -1 if enabled by default.  */
 619   int pei386_runtime_pseudo_reloc;
 620
 621   /* How many spare .dynamic DT_NULL entries should be added?  */
 622   unsigned int spare_dynamic_tags;
 623
 624   /* May be used to set DT_FLAGS for ELF. */
 625   bfd_vma flags;
 626
 627   /* May be used to set DT_FLAGS_1 for ELF. */
 628   bfd_vma flags_1;
 629
 630   /* Start and end of RELRO region.  */
 631   bfd_vma relro_start, relro_end;
 632
 633   /* List of symbols should be dynamic.  */
 634   struct bfd_elf_dynamic_list *dynamic_list;
 635
 636   /* The version information.  */
 637   struct bfd_elf_version_tree *version_info;
 638 };
 639
 640 /* This structures holds a set of callback functions.  These are called
 641    by the BFD linker routines.  */
 642
 643 struct bfd_link_callbacks
 644 {
 645   /* A function which is called when an object is added from an
 646      archive.  ABFD is the archive element being added.  NAME is the
 647      name of the symbol which caused the archive element to be pulled
 648      in.  This function may set *SUBSBFD to point to an alternative
 649      BFD from which symbols should in fact be added in place of the
 650      original BFD's symbols.  Returns TRUE if the object should be
 651      added, FALSE if it should be skipped.  */
 652   bfd_boolean (*add_archive_element)
 653     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 654   /* A function which is called when a symbol is found with multiple
 655      definitions.  H is the symbol which is defined multiple times.
 656      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 657      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 658   void (*multiple_definition)
 659     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 660      bfd *nbfd, asection *nsec, bfd_vma nval);
 661   /* A function which is called when a common symbol is defined
 662      multiple times.  H is the symbol appearing multiple times.
 663      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 664      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 665      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 666      is the size of the new symbol.  */
 667   void (*multiple_common)
 668     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 669      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 670   /* A function which is called to add a symbol to a set.  ENTRY is
 671      the link hash table entry for the set itself (e.g.,
 672      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 673      the set when generating a relocatable file, and is also used to
 674      get the size of the entry when generating an executable file.
 675      ABFD, SEC and VALUE identify the value to add to the set.  */
 676   void (*add_to_set)
 677     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 678      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 679   /* A function which is called when the name of a g++ constructor or
 680      destructor is found.  This is only called by some object file
 681      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 682      destructor.  This will use BFD_RELOC_CTOR when generating a
 683      relocatable file.  NAME is the name of the symbol found.  ABFD,
 684      SECTION and VALUE are the value of the symbol.  */
 685   void (*constructor)
 686     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 687      bfd *abfd, asection *sec, bfd_vma value);
 688   /* A function which is called to issue a linker warning.  For
 689      example, this is called when there is a reference to a warning
 690      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 691      of the symbol which triggered the warning; it may be NULL if
 692      there is none.  ABFD, SECTION and ADDRESS identify the location
 693      which trigerred the warning; either ABFD or SECTION or both may
 694      be NULL if the location is not known.  */
 695   void (*warning)
 696     (struct bfd_link_info *, const char *warning, const char *symbol,
 697      bfd *abfd, asection *section, bfd_vma address);
 698   /* A function which is called when a relocation is attempted against
 699      an undefined symbol.  NAME is the symbol which is undefined.
 700      ABFD, SECTION and ADDRESS identify the location from which the
 701      reference is made. IS_FATAL indicates whether an undefined symbol is
 702      a fatal error or not. In some cases SECTION may be NULL.  */
 703   void (*undefined_symbol)
 704     (struct bfd_link_info *, const char *name, bfd *abfd,
 705      asection *section, bfd_vma address, bfd_boolean is_fatal);
 706   /* A function which is called when a reloc overflow occurs. ENTRY is
 707      the link hash table entry for the symbol the reloc is against.
 708      NAME is the name of the local symbol or section the reloc is
 709      against, RELOC_NAME is the name of the relocation, and ADDEND is
 710      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 711      location at which the overflow occurs; if this is the result of a
 712      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 713      ABFD will be NULL.  */
 714   void (*reloc_overflow)
 715     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 716      const char *name, const char *reloc_name, bfd_vma addend,
 717      bfd *abfd, asection *section, bfd_vma address);
 718   /* A function which is called when a dangerous reloc is performed.
 719      MESSAGE is an appropriate message.
 720      ABFD, SECTION and ADDRESS identify the location at which the
 721      problem occurred; if this is the result of a
 722      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 723      ABFD will be NULL.  */
 724   void (*reloc_dangerous)
 725     (struct bfd_link_info *, const char *message,
 726      bfd *abfd, asection *section, bfd_vma address);
 727   /* A function which is called when a reloc is found to be attached
 728      to a symbol which is not being written out.  NAME is the name of
 729      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 730      the reloc; if this is the result of a
 731      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 732      ABFD will be NULL.  */
 733   void (*unattached_reloc)
 734     (struct bfd_link_info *, const char *name,
 735      bfd *abfd, asection *section, bfd_vma address);
 736   /* A function which is called when a symbol in notice_hash is
 737      defined or referenced.  H is the symbol, INH the indirect symbol
 738      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 739      the symbol.  If SECTION is bfd_und_section, this is a reference.
 740      FLAGS are the symbol BSF_* flags.  */
 741   bfd_boolean (*notice)
 742     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 743      struct bfd_link_hash_entry *inh,
 744      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 745   /* Error or warning link info message.  */
 746   void (*einfo)
 747     (const char *fmt, ...);
 748   /* General link info message.  */
 749   void (*info)
 750     (const char *fmt, ...);
 751   /* Message to be printed in linker map file.  */
 752   void (*minfo)
 753     (const char *fmt, ...);
 754   /* This callback provides a chance for users of the BFD library to
 755      override its decision about whether to place two adjacent sections
 756      into the same segment.  */
 757   bfd_boolean (*override_segment_assignment)
 758     (struct bfd_link_info *, bfd * abfd,
 759      asection * current_section, asection * previous_section,
 760      bfd_boolean new_segment);
 761 };
 762 \f
 763 /* The linker builds link_order structures which tell the code how to
 764    include input data in the output file.  */
 765
 766 /* These are the types of link_order structures.  */
 767
 768 enum bfd_link_order_type
 769 {
 770   bfd_undefined_link_order,     /* Undefined.  */
 771   bfd_indirect_link_order,      /* Built from a section.  */
 772   bfd_data_link_order,          /* Set to explicit data.  */
 773   bfd_section_reloc_link_order, /* Relocate against a section.  */
 774   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 775 };
 776
 777 /* This is the link_order structure itself.  These form a chain
 778    attached to the output section whose contents they are describing.  */
 779
 780 struct bfd_link_order
 781 {
 782   /* Next link_order in chain.  */
 783   struct bfd_link_order *next;
 784   /* Type of link_order.  */
 785   enum bfd_link_order_type type;
 786   /* Offset within output section.  */
 787   bfd_vma offset;
 788   /* Size within output section.  */
 789   bfd_size_type size;
 790   /* Type specific information.  */
 791   union
 792     {
 793       struct
 794         {
 795           /* Section to include.  If this is used, then
 796              section->output_section must be the section the
 797              link_order is attached to, section->output_offset must
 798              equal the link_order offset field, and section->size
 799              must equal the link_order size field.  Maybe these
 800              restrictions should be relaxed someday.  */
 801           asection *section;
 802         } indirect;
 803       struct
 804         {
 805           /* Size of contents, or zero when contents should be filled by
 806              the architecture-dependent fill function.
 807              A non-zero value allows filling of the output section
 808              with an arbitrary repeated pattern.  */
 809           unsigned int size;
 810           /* Data to put into file.  */
 811           bfd_byte *contents;
 812         } data;
 813       struct
 814         {
 815           /* Description of reloc to generate.  Used for
 816              bfd_section_reloc_link_order and
 817              bfd_symbol_reloc_link_order.  */
 818           struct bfd_link_order_reloc *p;
 819         } reloc;
 820     } u;
 821 };
 822
 823 /* A linker order of type bfd_section_reloc_link_order or
 824    bfd_symbol_reloc_link_order means to create a reloc against a
 825    section or symbol, respectively.  This is used to implement -Ur to
 826    generate relocs for the constructor tables.  The
 827    bfd_link_order_reloc structure describes the reloc that BFD should
 828    create.  It is similar to a arelent, but I didn't use arelent
 829    because the linker does not know anything about most symbols, and
 830    any asymbol structure it creates will be partially meaningless.
 831    This information could logically be in the bfd_link_order struct,
 832    but I didn't want to waste the space since these types of relocs
 833    are relatively rare.  */
 834
 835 struct bfd_link_order_reloc
 836 {
 837   /* Reloc type.  */
 838   bfd_reloc_code_real_type reloc;
 839
 840   union
 841     {
 842       /* For type bfd_section_reloc_link_order, this is the section
 843          the reloc should be against.  This must be a section in the
 844          output BFD, not any of the input BFDs.  */
 845       asection *section;
 846       /* For type bfd_symbol_reloc_link_order, this is the name of the
 847          symbol the reloc should be against.  */
 848       const char *name;
 849     } u;
 850
 851   /* Addend to use.  The object file should contain zero.  The BFD
 852      backend is responsible for filling in the contents of the object
 853      file correctly.  For some object file formats (e.g., COFF) the
 854      addend must be stored into in the object file, and for some
 855      (e.g., SPARC a.out) it is kept in the reloc.  */
 856   bfd_vma addend;
 857 };
 858
 859 /* Allocate a new link_order for a section.  */
 860 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 861
 862 /* These structures are used to describe version information for the
 863    ELF linker.  These structures could be manipulated entirely inside
 864    BFD, but it would be a pain.  Instead, the regular linker sets up
 865    these structures, and then passes them into BFD.  */
 866
 867 /* Glob pattern for a version.  */
 868
 869 struct bfd_elf_version_expr
 870 {
 871   /* Next glob pattern for this version.  */
 872   struct bfd_elf_version_expr *next;
 873   /* Glob pattern.  */
 874   const char *pattern;
 875   /* Set if pattern is not a glob.  */
 876   unsigned int literal : 1;
 877   /* Defined by ".symver".  */
 878   unsigned int symver : 1;
 879   /* Defined by version script.  */
 880   unsigned int script : 1;
 881   /* Pattern type.  */
 882 #define BFD_ELF_VERSION_C_TYPE          1
 883 #define BFD_ELF_VERSION_CXX_TYPE        2
 884 #define BFD_ELF_VERSION_JAVA_TYPE       4
 885   unsigned int mask : 3;
 886 };
 887
 888 struct bfd_elf_version_expr_head
 889 {
 890   /* List of all patterns, both wildcards and non-wildcards.  */
 891   struct bfd_elf_version_expr *list;
 892   /* Hash table for non-wildcards.  */
 893   void *htab;
 894   /* Remaining patterns.  */
 895   struct bfd_elf_version_expr *remaining;
 896   /* What kind of pattern types are present in list (bitmask).  */
 897   unsigned int mask;
 898 };
 899
 900 /* Version dependencies.  */
 901
 902 struct bfd_elf_version_deps
 903 {
 904   /* Next dependency for this version.  */
 905   struct bfd_elf_version_deps *next;
 906   /* The version which this version depends upon.  */
 907   struct bfd_elf_version_tree *version_needed;
 908 };
 909
 910 /* A node in the version tree.  */
 911
 912 struct bfd_elf_version_tree
 913 {
 914   /* Next version.  */
 915   struct bfd_elf_version_tree *next;
 916   /* Name of this version.  */
 917   const char *name;
 918   /* Version number.  */
 919   unsigned int vernum;
 920   /* Regular expressions for global symbols in this version.  */
 921   struct bfd_elf_version_expr_head globals;
 922   /* Regular expressions for local symbols in this version.  */
 923   struct bfd_elf_version_expr_head locals;
 924   /* List of versions which this version depends upon.  */
 925   struct bfd_elf_version_deps *deps;
 926   /* Index of the version name.  This is used within BFD.  */
 927   unsigned int name_indx;
 928   /* Whether this version tree was used.  This is used within BFD.  */
 929   int used;
 930   /* Matching hook.  */
 931   struct bfd_elf_version_expr *(*match)
 932     (struct bfd_elf_version_expr_head *head,
 933      struct bfd_elf_version_expr *prev, const char *sym);
 934 };
 935
 936 struct bfd_elf_dynamic_list
 937 {
 938   struct bfd_elf_version_expr_head head;
 939   struct bfd_elf_version_expr *(*match)
 940     (struct bfd_elf_version_expr_head *head,
 941      struct bfd_elf_version_expr *prev, const char *sym);
 942 };
 943
 944 #endif