include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2017 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   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 390      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 391   unsigned int eh_frame_hdr_type: 2;
 392
 393   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 394   unsigned int warn_shared_textrel: 1;
 395
 396   /* TRUE if we should error when adding a DT_TEXTREL.  */
 397   unsigned int error_textrel: 1;
 398
 399   /* TRUE if .hash section should be created.  */
 400   unsigned int emit_hash: 1;
 401
 402   /* TRUE if .gnu.hash section should be created.  */
 403   unsigned int emit_gnu_hash: 1;
 404
 405   /* If TRUE reduce memory overheads, at the expense of speed. This will
 406      cause map file generation to use an O(N^2) algorithm and disable
 407      caching ELF symbol buffer.  */
 408   unsigned int reduce_memory_overheads: 1;
 409
 410   /* TRUE if the output file should be in a traditional format.  This
 411      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 412      on the output file, but may be checked when reading the input
 413      files.  */
 414   unsigned int traditional_format: 1;
 415
 416   /* TRUE if non-PLT relocs should be merged into one reloc section
 417      and sorted so that relocs against the same symbol come together.  */
 418   unsigned int combreloc: 1;
 419
 420   /* TRUE if a default symbol version should be created and used for
 421      imported symbols.  */
 422   unsigned int default_imported_symver: 1;
 423
 424   /* TRUE if the new ELF dynamic tags are enabled. */
 425   unsigned int new_dtags: 1;
 426
 427   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 428      linker created sections, TRUE if it should be omitted.  */
 429   unsigned int no_ld_generated_unwind_info: 1;
 430
 431   /* TRUE if BFD should generate a "task linked" object file,
 432      similar to relocatable but also with globals converted to
 433      statics.  */
 434   unsigned int task_link: 1;
 435
 436   /* TRUE if ok to have multiple definition.  */
 437   unsigned int allow_multiple_definition: 1;
 438
 439   /* TRUE if ok to have version with no definition.  */
 440   unsigned int allow_undefined_version: 1;
 441
 442   /* TRUE if some symbols have to be dynamic, controlled by
 443      --dynamic-list command line options.  */
 444   unsigned int dynamic: 1;
 445
 446   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 447      flags.  */
 448   unsigned int execstack: 1;
 449
 450   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 451      flags.  */
 452   unsigned int noexecstack: 1;
 453
 454   /* TRUE if we want to produced optimized output files.  This might
 455      need much more time and therefore must be explicitly selected.  */
 456   unsigned int optimize: 1;
 457
 458   /* TRUE if user should be informed of removed unreferenced sections.  */
 459   unsigned int print_gc_sections: 1;
 460
 461   /* TRUE if we should warn alternate ELF machine code.  */
 462   unsigned int warn_alternate_em: 1;
 463
 464   /* TRUE if the linker script contained an explicit PHDRS command.  */
 465   unsigned int user_phdrs: 1;
 466
 467   /* TRUE if we should check relocations after all input files have
 468      been opened.  */
 469   unsigned int check_relocs_after_open_input: 1;
 470
 471   /* TRUE if BND prefix in PLT entries is always generated.  */
 472   unsigned int bndplt: 1;
 473
 474   /* TRUE if IBT-enabled PLT entries should be generated.  */
 475   unsigned int ibtplt: 1;
 476
 477   /* TRUE if GNU_PROPERTY_X86_FEATURE_1_IBT should be generated.  */
 478   unsigned int ibt: 1;
 479
 480   /* TRUE if GNU_PROPERTY_X86_FEATURE_1_SHSTK should be generated.  */
 481   unsigned int shstk: 1;
 482
 483   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 484   unsigned int nointerp: 1;
 485
 486   /* TRUE if we shouldn't check relocation overflow.  */
 487   unsigned int no_reloc_overflow_check: 1;
 488
 489   /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction.  */
 490   unsigned int call_nop_as_suffix : 1;
 491
 492   /* The 1-byte NOP for x86 call instruction.  */
 493   char call_nop_byte;
 494
 495   /* Char that may appear as the first char of a symbol, but should be
 496      skipped (like symbol_leading_char) when looking up symbols in
 497      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 498   char wrap_char;
 499
 500   /* Separator between archive and filename in linker script filespecs.  */
 501   char path_separator;
 502
 503   /* Compress DWARF debug sections.  */
 504   enum compressed_debug_section_type compress_debug;
 505
 506   /* Default stack size.  Zero means default (often zero itself), -1
 507      means explicitly zero-sized.  */
 508   bfd_signed_vma stacksize;
 509
 510   /* Enable or disable target specific optimizations.
 511
 512      Not all targets have optimizations to enable.
 513
 514      Normally these optimizations are disabled by default but some targets
 515      prefer to enable them by default.  So this field is a tri-state variable.
 516      The values are:
 517
 518      zero: Enable the optimizations (either from --relax being specified on
 519        the command line or the backend's before_allocation emulation function.
 520
 521      positive: The user has requested that these optimizations be disabled.
 522        (Via the --no-relax command line option).
 523
 524      negative: The optimizations are disabled.  (Set when initializing the
 525        args_type structure in ldmain.c:main.  */
 526   signed int disable_target_specific_optimizations;
 527
 528   /* Function callbacks.  */
 529   const struct bfd_link_callbacks *callbacks;
 530
 531   /* Hash table handled by BFD.  */
 532   struct bfd_link_hash_table *hash;
 533
 534   /* Hash table of symbols to keep.  This is NULL unless strip is
 535      strip_some.  */
 536   struct bfd_hash_table *keep_hash;
 537
 538   /* Hash table of symbols to report back via the notice callback.  If
 539      this is NULL, and notice_all is FALSE, then no symbols are
 540      reported back.  */
 541   struct bfd_hash_table *notice_hash;
 542
 543   /* Hash table of symbols which are being wrapped (the --wrap linker
 544      option).  If this is NULL, no symbols are being wrapped.  */
 545   struct bfd_hash_table *wrap_hash;
 546
 547   /* Hash table of symbols which may be left unresolved during
 548      a link.  If this is NULL, no symbols can be left unresolved.  */
 549   struct bfd_hash_table *ignore_hash;
 550
 551   /* The output BFD.  */
 552   bfd *output_bfd;
 553
 554   /* The import library generated.  */
 555   bfd *out_implib_bfd;
 556
 557   /* The list of input BFD's involved in the link.  These are chained
 558      together via the link.next field.  */
 559   bfd *input_bfds;
 560   bfd **input_bfds_tail;
 561
 562   /* If a symbol should be created for each input BFD, this is section
 563      where those symbols should be placed.  It must be a section in
 564      the output BFD.  It may be NULL, in which case no such symbols
 565      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 566      linker command language.  */
 567   asection *create_object_symbols_section;
 568
 569   /* List of global symbol names that are starting points for marking
 570      sections against garbage collection.  */
 571   struct bfd_sym_chain *gc_sym_list;
 572
 573   /* If a base output file is wanted, then this points to it */
 574   void *base_file;
 575
 576   /* The function to call when the executable or shared object is
 577      loaded.  */
 578   const char *init_function;
 579
 580   /* The function to call when the executable or shared object is
 581      unloaded.  */
 582   const char *fini_function;
 583
 584   /* Number of relaxation passes.  Usually only one relaxation pass
 585      is needed.  But a backend can have as many relaxation passes as
 586      necessary.  During bfd_relax_section call, it is set to the
 587      current pass, starting from 0.  */
 588   int relax_pass;
 589
 590   /* Number of relaxation trips.  This number is incremented every
 591      time the relaxation pass is restarted due to a previous
 592      relaxation returning true in *AGAIN.  */
 593   int relax_trip;
 594
 595   /* > 0 to treat protected data defined in the shared library as
 596      reference external.  0 to treat it as internal.  -1 to let
 597      backend to decide.  */
 598   int extern_protected_data;
 599
 600   /* 1 to make undefined weak symbols dynamic when building a dynamic
 601      object.  0 to resolve undefined weak symbols to zero.  -1 to let
 602      the backend decide.  */
 603   int dynamic_undefined_weak;
 604
 605   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 606      should be generated/linked against.  Set to 1 if this feature
 607      is explicitly requested by the user, -1 if enabled by default.  */
 608   int pei386_auto_import;
 609
 610   /* Non-zero if runtime relocs for DATA items with non-zero addends
 611      in pei386 DLLs should be generated.  Set to 1 if this feature
 612      is explicitly requested by the user, -1 if enabled by default.  */
 613   int pei386_runtime_pseudo_reloc;
 614
 615   /* How many spare .dynamic DT_NULL entries should be added?  */
 616   unsigned int spare_dynamic_tags;
 617
 618   /* May be used to set DT_FLAGS for ELF. */
 619   bfd_vma flags;
 620
 621   /* May be used to set DT_FLAGS_1 for ELF. */
 622   bfd_vma flags_1;
 623
 624   /* Start and end of RELRO region.  */
 625   bfd_vma relro_start, relro_end;
 626
 627   /* List of symbols should be dynamic.  */
 628   struct bfd_elf_dynamic_list *dynamic_list;
 629
 630   /* The version information.  */
 631   struct bfd_elf_version_tree *version_info;
 632 };
 633
 634 /* This structures holds a set of callback functions.  These are called
 635    by the BFD linker routines.  */
 636
 637 struct bfd_link_callbacks
 638 {
 639   /* A function which is called when an object is added from an
 640      archive.  ABFD is the archive element being added.  NAME is the
 641      name of the symbol which caused the archive element to be pulled
 642      in.  This function may set *SUBSBFD to point to an alternative
 643      BFD from which symbols should in fact be added in place of the
 644      original BFD's symbols.  Returns TRUE if the object should be
 645      added, FALSE if it should be skipped.  */
 646   bfd_boolean (*add_archive_element)
 647     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 648   /* A function which is called when a symbol is found with multiple
 649      definitions.  H is the symbol which is defined multiple times.
 650      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 651      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 652   void (*multiple_definition)
 653     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 654      bfd *nbfd, asection *nsec, bfd_vma nval);
 655   /* A function which is called when a common symbol is defined
 656      multiple times.  H is the symbol appearing multiple times.
 657      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 658      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 659      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 660      is the size of the new symbol.  */
 661   void (*multiple_common)
 662     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 663      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 664   /* A function which is called to add a symbol to a set.  ENTRY is
 665      the link hash table entry for the set itself (e.g.,
 666      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 667      the set when generating a relocatable file, and is also used to
 668      get the size of the entry when generating an executable file.
 669      ABFD, SEC and VALUE identify the value to add to the set.  */
 670   void (*add_to_set)
 671     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 672      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 673   /* A function which is called when the name of a g++ constructor or
 674      destructor is found.  This is only called by some object file
 675      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 676      destructor.  This will use BFD_RELOC_CTOR when generating a
 677      relocatable file.  NAME is the name of the symbol found.  ABFD,
 678      SECTION and VALUE are the value of the symbol.  */
 679   void (*constructor)
 680     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 681      bfd *abfd, asection *sec, bfd_vma value);
 682   /* A function which is called to issue a linker warning.  For
 683      example, this is called when there is a reference to a warning
 684      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 685      of the symbol which triggered the warning; it may be NULL if
 686      there is none.  ABFD, SECTION and ADDRESS identify the location
 687      which trigerred the warning; either ABFD or SECTION or both may
 688      be NULL if the location is not known.  */
 689   void (*warning)
 690     (struct bfd_link_info *, const char *warning, const char *symbol,
 691      bfd *abfd, asection *section, bfd_vma address);
 692   /* A function which is called when a relocation is attempted against
 693      an undefined symbol.  NAME is the symbol which is undefined.
 694      ABFD, SECTION and ADDRESS identify the location from which the
 695      reference is made. IS_FATAL indicates whether an undefined symbol is
 696      a fatal error or not. In some cases SECTION may be NULL.  */
 697   void (*undefined_symbol)
 698     (struct bfd_link_info *, const char *name, bfd *abfd,
 699      asection *section, bfd_vma address, bfd_boolean is_fatal);
 700   /* A function which is called when a reloc overflow occurs. ENTRY is
 701      the link hash table entry for the symbol the reloc is against.
 702      NAME is the name of the local symbol or section the reloc is
 703      against, RELOC_NAME is the name of the relocation, and ADDEND is
 704      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 705      location at which the overflow occurs; if this is the result of a
 706      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 707      ABFD will be NULL.  */
 708   void (*reloc_overflow)
 709     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 710      const char *name, const char *reloc_name, bfd_vma addend,
 711      bfd *abfd, asection *section, bfd_vma address);
 712   /* A function which is called when a dangerous reloc is performed.
 713      MESSAGE is an appropriate message.
 714      ABFD, SECTION and ADDRESS identify the location at which the
 715      problem occurred; if this is the result of a
 716      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 717      ABFD will be NULL.  */
 718   void (*reloc_dangerous)
 719     (struct bfd_link_info *, const char *message,
 720      bfd *abfd, asection *section, bfd_vma address);
 721   /* A function which is called when a reloc is found to be attached
 722      to a symbol which is not being written out.  NAME is the name of
 723      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 724      the reloc; if this is the result of a
 725      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 726      ABFD will be NULL.  */
 727   void (*unattached_reloc)
 728     (struct bfd_link_info *, const char *name,
 729      bfd *abfd, asection *section, bfd_vma address);
 730   /* A function which is called when a symbol in notice_hash is
 731      defined or referenced.  H is the symbol, INH the indirect symbol
 732      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 733      the symbol.  If SECTION is bfd_und_section, this is a reference.
 734      FLAGS are the symbol BSF_* flags.  */
 735   bfd_boolean (*notice)
 736     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 737      struct bfd_link_hash_entry *inh,
 738      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 739   /* Error or warning link info message.  */
 740   void (*einfo)
 741     (const char *fmt, ...);
 742   /* General link info message.  */
 743   void (*info)
 744     (const char *fmt, ...);
 745   /* Message to be printed in linker map file.  */
 746   void (*minfo)
 747     (const char *fmt, ...);
 748   /* This callback provides a chance for users of the BFD library to
 749      override its decision about whether to place two adjacent sections
 750      into the same segment.  */
 751   bfd_boolean (*override_segment_assignment)
 752     (struct bfd_link_info *, bfd * abfd,
 753      asection * current_section, asection * previous_section,
 754      bfd_boolean new_segment);
 755 };
 756 \f
 757 /* The linker builds link_order structures which tell the code how to
 758    include input data in the output file.  */
 759
 760 /* These are the types of link_order structures.  */
 761
 762 enum bfd_link_order_type
 763 {
 764   bfd_undefined_link_order,     /* Undefined.  */
 765   bfd_indirect_link_order,      /* Built from a section.  */
 766   bfd_data_link_order,          /* Set to explicit data.  */
 767   bfd_section_reloc_link_order, /* Relocate against a section.  */
 768   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 769 };
 770
 771 /* This is the link_order structure itself.  These form a chain
 772    attached to the output section whose contents they are describing.  */
 773
 774 struct bfd_link_order
 775 {
 776   /* Next link_order in chain.  */
 777   struct bfd_link_order *next;
 778   /* Type of link_order.  */
 779   enum bfd_link_order_type type;
 780   /* Offset within output section.  */
 781   bfd_vma offset;
 782   /* Size within output section.  */
 783   bfd_size_type size;
 784   /* Type specific information.  */
 785   union
 786     {
 787       struct
 788         {
 789           /* Section to include.  If this is used, then
 790              section->output_section must be the section the
 791              link_order is attached to, section->output_offset must
 792              equal the link_order offset field, and section->size
 793              must equal the link_order size field.  Maybe these
 794              restrictions should be relaxed someday.  */
 795           asection *section;
 796         } indirect;
 797       struct
 798         {
 799           /* Size of contents, or zero when contents should be filled by
 800              the architecture-dependent fill function.
 801              A non-zero value allows filling of the output section
 802              with an arbitrary repeated pattern.  */
 803           unsigned int size;
 804           /* Data to put into file.  */
 805           bfd_byte *contents;
 806         } data;
 807       struct
 808         {
 809           /* Description of reloc to generate.  Used for
 810              bfd_section_reloc_link_order and
 811              bfd_symbol_reloc_link_order.  */
 812           struct bfd_link_order_reloc *p;
 813         } reloc;
 814     } u;
 815 };
 816
 817 /* A linker order of type bfd_section_reloc_link_order or
 818    bfd_symbol_reloc_link_order means to create a reloc against a
 819    section or symbol, respectively.  This is used to implement -Ur to
 820    generate relocs for the constructor tables.  The
 821    bfd_link_order_reloc structure describes the reloc that BFD should
 822    create.  It is similar to a arelent, but I didn't use arelent
 823    because the linker does not know anything about most symbols, and
 824    any asymbol structure it creates will be partially meaningless.
 825    This information could logically be in the bfd_link_order struct,
 826    but I didn't want to waste the space since these types of relocs
 827    are relatively rare.  */
 828
 829 struct bfd_link_order_reloc
 830 {
 831   /* Reloc type.  */
 832   bfd_reloc_code_real_type reloc;
 833
 834   union
 835     {
 836       /* For type bfd_section_reloc_link_order, this is the section
 837          the reloc should be against.  This must be a section in the
 838          output BFD, not any of the input BFDs.  */
 839       asection *section;
 840       /* For type bfd_symbol_reloc_link_order, this is the name of the
 841          symbol the reloc should be against.  */
 842       const char *name;
 843     } u;
 844
 845   /* Addend to use.  The object file should contain zero.  The BFD
 846      backend is responsible for filling in the contents of the object
 847      file correctly.  For some object file formats (e.g., COFF) the
 848      addend must be stored into in the object file, and for some
 849      (e.g., SPARC a.out) it is kept in the reloc.  */
 850   bfd_vma addend;
 851 };
 852
 853 /* Allocate a new link_order for a section.  */
 854 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 855
 856 /* These structures are used to describe version information for the
 857    ELF linker.  These structures could be manipulated entirely inside
 858    BFD, but it would be a pain.  Instead, the regular linker sets up
 859    these structures, and then passes them into BFD.  */
 860
 861 /* Glob pattern for a version.  */
 862
 863 struct bfd_elf_version_expr
 864 {
 865   /* Next glob pattern for this version.  */
 866   struct bfd_elf_version_expr *next;
 867   /* Glob pattern.  */
 868   const char *pattern;
 869   /* Set if pattern is not a glob.  */
 870   unsigned int literal : 1;
 871   /* Defined by ".symver".  */
 872   unsigned int symver : 1;
 873   /* Defined by version script.  */
 874   unsigned int script : 1;
 875   /* Pattern type.  */
 876 #define BFD_ELF_VERSION_C_TYPE          1
 877 #define BFD_ELF_VERSION_CXX_TYPE        2
 878 #define BFD_ELF_VERSION_JAVA_TYPE       4
 879   unsigned int mask : 3;
 880 };
 881
 882 struct bfd_elf_version_expr_head
 883 {
 884   /* List of all patterns, both wildcards and non-wildcards.  */
 885   struct bfd_elf_version_expr *list;
 886   /* Hash table for non-wildcards.  */
 887   void *htab;
 888   /* Remaining patterns.  */
 889   struct bfd_elf_version_expr *remaining;
 890   /* What kind of pattern types are present in list (bitmask).  */
 891   unsigned int mask;
 892 };
 893
 894 /* Version dependencies.  */
 895
 896 struct bfd_elf_version_deps
 897 {
 898   /* Next dependency for this version.  */
 899   struct bfd_elf_version_deps *next;
 900   /* The version which this version depends upon.  */
 901   struct bfd_elf_version_tree *version_needed;
 902 };
 903
 904 /* A node in the version tree.  */
 905
 906 struct bfd_elf_version_tree
 907 {
 908   /* Next version.  */
 909   struct bfd_elf_version_tree *next;
 910   /* Name of this version.  */
 911   const char *name;
 912   /* Version number.  */
 913   unsigned int vernum;
 914   /* Regular expressions for global symbols in this version.  */
 915   struct bfd_elf_version_expr_head globals;
 916   /* Regular expressions for local symbols in this version.  */
 917   struct bfd_elf_version_expr_head locals;
 918   /* List of versions which this version depends upon.  */
 919   struct bfd_elf_version_deps *deps;
 920   /* Index of the version name.  This is used within BFD.  */
 921   unsigned int name_indx;
 922   /* Whether this version tree was used.  This is used within BFD.  */
 923   int used;
 924   /* Matching hook.  */
 925   struct bfd_elf_version_expr *(*match)
 926     (struct bfd_elf_version_expr_head *head,
 927      struct bfd_elf_version_expr *prev, const char *sym);
 928 };
 929
 930 struct bfd_elf_dynamic_list
 931 {
 932   struct bfd_elf_version_expr_head head;
 933   struct bfd_elf_version_expr *(*match)
 934     (struct bfd_elf_version_expr_head *head,
 935      struct bfd_elf_version_expr *prev, const char *sym);
 936 };
 937
 938 #endif