include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2016 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 object file, as distict from a LTO
 104      IR object file.  */
 105   unsigned int non_ir_ref : 1;
 106
 107   /* Symbol is a built-in define.  These will be overridden by PROVIDE
 108      in a linker script.  */
 109   unsigned int linker_def : 1;
 110
 111   /* A union of information depending upon the type.  */
 112   union
 113     {
 114       /* Nothing is kept for bfd_hash_new.  */
 115       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 116       struct
 117         {
 118           /* Undefined and common symbols are kept in a linked list through
 119              this field.  This field is present in all of the union element
 120              so that we don't need to remove entries from the list when we
 121              change their type.  Removing entries would either require the
 122              list to be doubly linked, which would waste more memory, or
 123              require a traversal.  When an undefined or common symbol is
 124              created, it should be added to this list, the head of which is in
 125              the link hash table itself.  As symbols are defined, they need
 126              not be removed from the list; anything which reads the list must
 127              doublecheck the symbol type.
 128
 129              Weak symbols are not kept on this list.
 130
 131              Defined and defweak symbols use this field as a reference marker.
 132              If the field is not NULL, or this structure is the tail of the
 133              undefined symbol list, the symbol has been referenced.  If the
 134              symbol is undefined and becomes defined, this field will
 135              automatically be non-NULL since the symbol will have been on the
 136              undefined symbol list.  */
 137           struct bfd_link_hash_entry *next;
 138           bfd *abfd;            /* BFD symbol was found in.  */
 139         } undef;
 140       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 141       struct
 142         {
 143           struct bfd_link_hash_entry *next;
 144           asection *section;    /* Symbol section.  */
 145           bfd_vma value;        /* Symbol value.  */
 146         } def;
 147       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 148       struct
 149         {
 150           struct bfd_link_hash_entry *next;
 151           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 152           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 153         } i;
 154       /* bfd_link_hash_common.  */
 155       struct
 156         {
 157           struct bfd_link_hash_entry *next;
 158           /* The linker needs to know three things about common
 159              symbols: the size, the alignment, and the section in
 160              which the symbol should be placed.  We store the size
 161              here, and we allocate a small structure to hold the
 162              section and the alignment.  The alignment is stored as a
 163              power of two.  We don't store all the information
 164              directly because we don't want to increase the size of
 165              the union; this structure is a major space user in the
 166              linker.  */
 167           struct bfd_link_hash_common_entry *p;
 168           bfd_size_type size;   /* Common symbol size.  */
 169         } c;
 170     } u;
 171 };
 172
 173 /* This is the link hash table.  It is a derived class of
 174    bfd_hash_table.  */
 175
 176 struct bfd_link_hash_table
 177 {
 178   /* The hash table itself.  */
 179   struct bfd_hash_table table;
 180   /* A linked list of undefined and common symbols, linked through the
 181      next field in the bfd_link_hash_entry structure.  */
 182   struct bfd_link_hash_entry *undefs;
 183   /* Entries are added to the tail of the undefs list.  */
 184   struct bfd_link_hash_entry *undefs_tail;
 185   /* Function to free the hash table on closing BFD.  */
 186   void (*hash_table_free) (bfd *);
 187   /* The type of the link hash table.  */
 188   enum bfd_link_hash_table_type type;
 189 };
 190
 191 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 192    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 193    the real symbol.  */
 194 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 195   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 196    bfd_boolean copy, bfd_boolean follow);
 197
 198 /* Look up an entry in the main linker hash table if the symbol might
 199    be wrapped.  This should only be used for references to an
 200    undefined symbol, not for definitions of a symbol.  */
 201
 202 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 203   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 204    bfd_boolean, bfd_boolean);
 205
 206 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 207    and the remainder is found in wrap_hash, return the real symbol.  */
 208
 209 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 210   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 211
 212 /* Traverse a link hash table.  */
 213 extern void bfd_link_hash_traverse
 214   (struct bfd_link_hash_table *,
 215     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 216     void *);
 217
 218 /* Add an entry to the undefs list.  */
 219 extern void bfd_link_add_undef
 220   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 221
 222 /* Remove symbols from the undefs list that don't belong there.  */
 223 extern void bfd_link_repair_undef_list
 224   (struct bfd_link_hash_table *table);
 225
 226 /* Read symbols and cache symbol pointer array in outsymbols.  */
 227 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 228
 229 struct bfd_sym_chain
 230 {
 231   struct bfd_sym_chain *next;
 232   const char *name;
 233 };
 234 \f
 235 /* How to handle unresolved symbols.
 236    There are four possibilities which are enumerated below:  */
 237 enum report_method
 238 {
 239   /* This is the initial value when then link_info structure is created.
 240      It allows the various stages of the linker to determine whether they
 241      allowed to set the value.  */
 242   RM_NOT_YET_SET = 0,
 243   RM_IGNORE,
 244   RM_GENERATE_WARNING,
 245   RM_GENERATE_ERROR
 246 };
 247
 248 typedef enum {with_flags, without_flags} flag_type;
 249
 250 /* A section flag list.  */
 251 struct flag_info_list
 252 {
 253   flag_type with;
 254   const char *name;
 255   bfd_boolean valid;
 256   struct flag_info_list *next;
 257 };
 258
 259 /* Section flag info.  */
 260 struct flag_info
 261 {
 262   flagword only_with_flags;
 263   flagword not_with_flags;
 264   struct flag_info_list *flag_list;
 265   bfd_boolean flags_initialized;
 266 };
 267
 268 struct bfd_elf_dynamic_list;
 269 struct bfd_elf_version_tree;
 270
 271 /* Types of output.  */
 272
 273 enum output_type
 274 {
 275   type_pde,
 276   type_pie,
 277   type_relocatable,
 278   type_dll,
 279 };
 280
 281 #define bfd_link_pde(info)         ((info)->type == type_pde)
 282 #define bfd_link_dll(info)         ((info)->type == type_dll)
 283 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 284 #define bfd_link_pie(info)         ((info)->type == type_pie)
 285 #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
 286 #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
 287
 288 /* This structure holds all the information needed to communicate
 289    between BFD and the linker when doing a link.  */
 290
 291 struct bfd_link_info
 292 {
 293   /* Output type.  */
 294   ENUM_BITFIELD (output_type) type : 2;
 295
 296   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 297   unsigned int symbolic: 1;
 298
 299   /* TRUE if executable should not contain copy relocs.
 300      Setting this true may result in a non-sharable text segment.  */
 301   unsigned int nocopyreloc: 1;
 302
 303   /* TRUE if BFD should export all symbols in the dynamic symbol table
 304      of an executable, rather than only those used.  */
 305   unsigned int export_dynamic: 1;
 306
 307   /* TRUE if a default symbol version should be created and used for
 308      exported symbols.  */
 309   unsigned int create_default_symver: 1;
 310
 311   /* TRUE if unreferenced sections should be removed.  */
 312   unsigned int gc_sections: 1;
 313
 314   /* TRUE if every symbol should be reported back via the notice
 315      callback.  */
 316   unsigned int notice_all: 1;
 317
 318   /* TRUE if the LTO plugin is active.  */
 319   unsigned int lto_plugin_active: 1;
 320
 321   /* TRUE if global symbols in discarded sections should be stripped.  */
 322   unsigned int strip_discarded: 1;
 323
 324   /* TRUE if all data symbols should be dynamic.  */
 325   unsigned int dynamic_data: 1;
 326
 327   /* Which symbols to strip.  */
 328   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 329
 330   /* Which local symbols to discard.  */
 331   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 332
 333   /* Whether to generate ELF common symbols with the STT_COMMON type.  */
 334   ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
 335
 336   /* Criteria for skipping symbols when determining
 337      whether to include an object from an archive. */
 338   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 339
 340   /* What to do with unresolved symbols in an object file.
 341      When producing executables the default is GENERATE_ERROR.
 342      When producing shared libraries the default is IGNORE.  The
 343      assumption with shared libraries is that the reference will be
 344      resolved at load/execution time.  */
 345   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 346
 347   /* What to do with unresolved symbols in a shared library.
 348      The same defaults apply.  */
 349   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 350
 351   /* TRUE if shared objects should be linked directly, not shared.  */
 352   unsigned int static_link: 1;
 353
 354   /* TRUE if symbols should be retained in memory, FALSE if they
 355      should be freed and reread.  */
 356   unsigned int keep_memory: 1;
 357
 358   /* TRUE if BFD should generate relocation information in the final
 359      executable.  */
 360   unsigned int emitrelocations: 1;
 361
 362   /* TRUE if PT_GNU_RELRO segment should be created.  */
 363   unsigned int relro: 1;
 364
 365   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 366      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 367   unsigned int eh_frame_hdr_type: 2;
 368
 369   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 370   unsigned int warn_shared_textrel: 1;
 371
 372   /* TRUE if we should error when adding a DT_TEXTREL.  */
 373   unsigned int error_textrel: 1;
 374
 375   /* TRUE if .hash section should be created.  */
 376   unsigned int emit_hash: 1;
 377
 378   /* TRUE if .gnu.hash section should be created.  */
 379   unsigned int emit_gnu_hash: 1;
 380
 381   /* If TRUE reduce memory overheads, at the expense of speed. This will
 382      cause map file generation to use an O(N^2) algorithm and disable
 383      caching ELF symbol buffer.  */
 384   unsigned int reduce_memory_overheads: 1;
 385
 386   /* TRUE if the output file should be in a traditional format.  This
 387      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 388      on the output file, but may be checked when reading the input
 389      files.  */
 390   unsigned int traditional_format: 1;
 391
 392   /* TRUE if non-PLT relocs should be merged into one reloc section
 393      and sorted so that relocs against the same symbol come together.  */
 394   unsigned int combreloc: 1;
 395
 396   /* TRUE if a default symbol version should be created and used for
 397      imported symbols.  */
 398   unsigned int default_imported_symver: 1;
 399
 400   /* TRUE if the new ELF dynamic tags are enabled. */
 401   unsigned int new_dtags: 1;
 402
 403   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 404      linker created sections, TRUE if it should be omitted.  */
 405   unsigned int no_ld_generated_unwind_info: 1;
 406
 407   /* TRUE if BFD should generate a "task linked" object file,
 408      similar to relocatable but also with globals converted to
 409      statics.  */
 410   unsigned int task_link: 1;
 411
 412   /* TRUE if ok to have multiple definition.  */
 413   unsigned int allow_multiple_definition: 1;
 414
 415   /* TRUE if ok to have version with no definition.  */
 416   unsigned int allow_undefined_version: 1;
 417
 418   /* TRUE if some symbols have to be dynamic, controlled by
 419      --dynamic-list command line options.  */
 420   unsigned int dynamic: 1;
 421
 422   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 423      flags.  */
 424   unsigned int execstack: 1;
 425
 426   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 427      flags.  */
 428   unsigned int noexecstack: 1;
 429
 430   /* TRUE if we want to produced optimized output files.  This might
 431      need much more time and therefore must be explicitly selected.  */
 432   unsigned int optimize: 1;
 433
 434   /* TRUE if user should be informed of removed unreferenced sections.  */
 435   unsigned int print_gc_sections: 1;
 436
 437   /* TRUE if we should warn alternate ELF machine code.  */
 438   unsigned int warn_alternate_em: 1;
 439
 440   /* TRUE if the linker script contained an explicit PHDRS command.  */
 441   unsigned int user_phdrs: 1;
 442
 443   /* TRUE if BND prefix in PLT entries is always generated.  */
 444   unsigned int bndplt: 1;
 445
 446   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 447   unsigned int nointerp: 1;
 448
 449   /* TRUE if we shouldn't check relocation overflow.  */
 450   unsigned int no_reloc_overflow_check: 1;
 451
 452   /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction.  */
 453   unsigned int call_nop_as_suffix : 1;
 454
 455   /* The 1-byte NOP for x86 call instruction.  */
 456   char call_nop_byte;
 457
 458   /* Char that may appear as the first char of a symbol, but should be
 459      skipped (like symbol_leading_char) when looking up symbols in
 460      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 461   char wrap_char;
 462
 463   /* Separator between archive and filename in linker script filespecs.  */
 464   char path_separator;
 465
 466   /* Compress DWARF debug sections.  */
 467   enum compressed_debug_section_type compress_debug;
 468
 469   /* Default stack size.  Zero means default (often zero itself), -1
 470      means explicitly zero-sized.  */
 471   bfd_signed_vma stacksize;
 472
 473   /* Enable or disable target specific optimizations.
 474
 475      Not all targets have optimizations to enable.
 476
 477      Normally these optimizations are disabled by default but some targets
 478      prefer to enable them by default.  So this field is a tri-state variable.
 479      The values are:
 480
 481      zero: Enable the optimizations (either from --relax being specified on
 482        the command line or the backend's before_allocation emulation function.
 483
 484      positive: The user has requested that these optimizations be disabled.
 485        (Via the --no-relax command line option).
 486
 487      negative: The optimizations are disabled.  (Set when initializing the
 488        args_type structure in ldmain.c:main.  */
 489   signed int disable_target_specific_optimizations;
 490
 491   /* Function callbacks.  */
 492   const struct bfd_link_callbacks *callbacks;
 493
 494   /* Hash table handled by BFD.  */
 495   struct bfd_link_hash_table *hash;
 496
 497   /* Hash table of symbols to keep.  This is NULL unless strip is
 498      strip_some.  */
 499   struct bfd_hash_table *keep_hash;
 500
 501   /* Hash table of symbols to report back via the notice callback.  If
 502      this is NULL, and notice_all is FALSE, then no symbols are
 503      reported back.  */
 504   struct bfd_hash_table *notice_hash;
 505
 506   /* Hash table of symbols which are being wrapped (the --wrap linker
 507      option).  If this is NULL, no symbols are being wrapped.  */
 508   struct bfd_hash_table *wrap_hash;
 509
 510   /* Hash table of symbols which may be left unresolved during
 511      a link.  If this is NULL, no symbols can be left unresolved.  */
 512   struct bfd_hash_table *ignore_hash;
 513
 514   /* The output BFD.  */
 515   bfd *output_bfd;
 516
 517   /* The list of input BFD's involved in the link.  These are chained
 518      together via the link.next field.  */
 519   bfd *input_bfds;
 520   bfd **input_bfds_tail;
 521
 522   /* If a symbol should be created for each input BFD, this is section
 523      where those symbols should be placed.  It must be a section in
 524      the output BFD.  It may be NULL, in which case no such symbols
 525      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 526      linker command language.  */
 527   asection *create_object_symbols_section;
 528
 529   /* List of global symbol names that are starting points for marking
 530      sections against garbage collection.  */
 531   struct bfd_sym_chain *gc_sym_list;
 532
 533   /* If a base output file is wanted, then this points to it */
 534   void *base_file;
 535
 536   /* The function to call when the executable or shared object is
 537      loaded.  */
 538   const char *init_function;
 539
 540   /* The function to call when the executable or shared object is
 541      unloaded.  */
 542   const char *fini_function;
 543
 544   /* Number of relaxation passes.  Usually only one relaxation pass
 545      is needed.  But a backend can have as many relaxation passes as
 546      necessary.  During bfd_relax_section call, it is set to the
 547      current pass, starting from 0.  */
 548   int relax_pass;
 549
 550   /* Number of relaxation trips.  This number is incremented every
 551      time the relaxation pass is restarted due to a previous
 552      relaxation returning true in *AGAIN.  */
 553   int relax_trip;
 554
 555   /* > 0 to treat protected data defined in the shared library as
 556      reference external.  0 to treat it as internal.  -1 to let
 557      backend to decide.  */
 558   int extern_protected_data;
 559
 560   /* > 0 to treat undefined weak symbol in the executable as dynamic,
 561      requiring dynamic relocation.  */
 562   int dynamic_undefined_weak;
 563
 564   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 565      should be generated/linked against.  Set to 1 if this feature
 566      is explicitly requested by the user, -1 if enabled by default.  */
 567   int pei386_auto_import;
 568
 569   /* Non-zero if runtime relocs for DATA items with non-zero addends
 570      in pei386 DLLs should be generated.  Set to 1 if this feature
 571      is explicitly requested by the user, -1 if enabled by default.  */
 572   int pei386_runtime_pseudo_reloc;
 573
 574   /* How many spare .dynamic DT_NULL entries should be added?  */
 575   unsigned int spare_dynamic_tags;
 576
 577   /* May be used to set DT_FLAGS for ELF. */
 578   bfd_vma flags;
 579
 580   /* May be used to set DT_FLAGS_1 for ELF. */
 581   bfd_vma flags_1;
 582
 583   /* Start and end of RELRO region.  */
 584   bfd_vma relro_start, relro_end;
 585
 586   /* List of symbols should be dynamic.  */
 587   struct bfd_elf_dynamic_list *dynamic_list;
 588
 589   /* The version information.  */
 590   struct bfd_elf_version_tree *version_info;
 591 };
 592
 593 /* This structures holds a set of callback functions.  These are called
 594    by the BFD linker routines.  Except for the info functions, the first
 595    argument to each callback function is the bfd_link_info structure
 596    being used and each function returns a boolean value.  If the
 597    function returns FALSE, then the BFD function which called it should
 598    return with a failure indication.  */
 599
 600 struct bfd_link_callbacks
 601 {
 602   /* A function which is called when an object is added from an
 603      archive.  ABFD is the archive element being added.  NAME is the
 604      name of the symbol which caused the archive element to be pulled
 605      in.  This function may set *SUBSBFD to point to an alternative
 606      BFD from which symbols should in fact be added in place of the
 607      original BFD's symbols.  */
 608   bfd_boolean (*add_archive_element)
 609     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 610   /* A function which is called when a symbol is found with multiple
 611      definitions.  H is the symbol which is defined multiple times.
 612      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 613      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 614   bfd_boolean (*multiple_definition)
 615     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 616      bfd *nbfd, asection *nsec, bfd_vma nval);
 617   /* A function which is called when a common symbol is defined
 618      multiple times.  H is the symbol appearing multiple times.
 619      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 620      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 621      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 622      is the size of the new symbol.  */
 623   bfd_boolean (*multiple_common)
 624     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 625      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 626   /* A function which is called to add a symbol to a set.  ENTRY is
 627      the link hash table entry for the set itself (e.g.,
 628      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 629      the set when generating a relocatable file, and is also used to
 630      get the size of the entry when generating an executable file.
 631      ABFD, SEC and VALUE identify the value to add to the set.  */
 632   bfd_boolean (*add_to_set)
 633     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 634      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 635   /* A function which is called when the name of a g++ constructor or
 636      destructor is found.  This is only called by some object file
 637      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 638      destructor.  This will use BFD_RELOC_CTOR when generating a
 639      relocatable file.  NAME is the name of the symbol found.  ABFD,
 640      SECTION and VALUE are the value of the symbol.  */
 641   bfd_boolean (*constructor)
 642     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 643      bfd *abfd, asection *sec, bfd_vma value);
 644   /* A function which is called to issue a linker warning.  For
 645      example, this is called when there is a reference to a warning
 646      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 647      of the symbol which triggered the warning; it may be NULL if
 648      there is none.  ABFD, SECTION and ADDRESS identify the location
 649      which trigerred the warning; either ABFD or SECTION or both may
 650      be NULL if the location is not known.  */
 651   bfd_boolean (*warning)
 652     (struct bfd_link_info *, const char *warning, const char *symbol,
 653      bfd *abfd, asection *section, bfd_vma address);
 654   /* A function which is called when a relocation is attempted against
 655      an undefined symbol.  NAME is the symbol which is undefined.
 656      ABFD, SECTION and ADDRESS identify the location from which the
 657      reference is made. IS_FATAL indicates whether an undefined symbol is
 658      a fatal error or not. In some cases SECTION may be NULL.  */
 659   bfd_boolean (*undefined_symbol)
 660     (struct bfd_link_info *, const char *name, bfd *abfd,
 661      asection *section, bfd_vma address, bfd_boolean is_fatal);
 662   /* A function which is called when a reloc overflow occurs. ENTRY is
 663      the link hash table entry for the symbol the reloc is against.
 664      NAME is the name of the local symbol or section the reloc is
 665      against, RELOC_NAME is the name of the relocation, and ADDEND is
 666      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 667      location at which the overflow occurs; if this is the result of a
 668      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 669      ABFD will be NULL.  */
 670   bfd_boolean (*reloc_overflow)
 671     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 672      const char *name, const char *reloc_name, bfd_vma addend,
 673      bfd *abfd, asection *section, bfd_vma address);
 674   /* A function which is called when a dangerous reloc is performed.
 675      MESSAGE is an appropriate message.
 676      ABFD, SECTION and ADDRESS identify the location at which the
 677      problem occurred; if this is the result of a
 678      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 679      ABFD will be NULL.  */
 680   bfd_boolean (*reloc_dangerous)
 681     (struct bfd_link_info *, const char *message,
 682      bfd *abfd, asection *section, bfd_vma address);
 683   /* A function which is called when a reloc is found to be attached
 684      to a symbol which is not being written out.  NAME is the name of
 685      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 686      the reloc; if this is the result of a
 687      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 688      ABFD will be NULL.  */
 689   bfd_boolean (*unattached_reloc)
 690     (struct bfd_link_info *, const char *name,
 691      bfd *abfd, asection *section, bfd_vma address);
 692   /* A function which is called when a symbol in notice_hash is
 693      defined or referenced.  H is the symbol, INH the indirect symbol
 694      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 695      the symbol.  If SECTION is bfd_und_section, this is a reference.
 696      FLAGS are the symbol BSF_* flags.  */
 697   bfd_boolean (*notice)
 698     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 699      struct bfd_link_hash_entry *inh,
 700      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 701   /* Error or warning link info message.  */
 702   void (*einfo)
 703     (const char *fmt, ...);
 704   /* General link info message.  */
 705   void (*info)
 706     (const char *fmt, ...);
 707   /* Message to be printed in linker map file.  */
 708   void (*minfo)
 709     (const char *fmt, ...);
 710   /* This callback provides a chance for users of the BFD library to
 711      override its decision about whether to place two adjacent sections
 712      into the same segment.  */
 713   bfd_boolean (*override_segment_assignment)
 714     (struct bfd_link_info *, bfd * abfd,
 715      asection * current_section, asection * previous_section,
 716      bfd_boolean new_segment);
 717 };
 718 \f
 719 /* The linker builds link_order structures which tell the code how to
 720    include input data in the output file.  */
 721
 722 /* These are the types of link_order structures.  */
 723
 724 enum bfd_link_order_type
 725 {
 726   bfd_undefined_link_order,     /* Undefined.  */
 727   bfd_indirect_link_order,      /* Built from a section.  */
 728   bfd_data_link_order,          /* Set to explicit data.  */
 729   bfd_section_reloc_link_order, /* Relocate against a section.  */
 730   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 731 };
 732
 733 /* This is the link_order structure itself.  These form a chain
 734    attached to the output section whose contents they are describing.  */
 735
 736 struct bfd_link_order
 737 {
 738   /* Next link_order in chain.  */
 739   struct bfd_link_order *next;
 740   /* Type of link_order.  */
 741   enum bfd_link_order_type type;
 742   /* Offset within output section.  */
 743   bfd_vma offset;
 744   /* Size within output section.  */
 745   bfd_size_type size;
 746   /* Type specific information.  */
 747   union
 748     {
 749       struct
 750         {
 751           /* Section to include.  If this is used, then
 752              section->output_section must be the section the
 753              link_order is attached to, section->output_offset must
 754              equal the link_order offset field, and section->size
 755              must equal the link_order size field.  Maybe these
 756              restrictions should be relaxed someday.  */
 757           asection *section;
 758         } indirect;
 759       struct
 760         {
 761           /* Size of contents, or zero when contents should be filled by
 762              the architecture-dependent fill function.
 763              A non-zero value allows filling of the output section
 764              with an arbitrary repeated pattern.  */
 765           unsigned int size;
 766           /* Data to put into file.  */
 767           bfd_byte *contents;
 768         } data;
 769       struct
 770         {
 771           /* Description of reloc to generate.  Used for
 772              bfd_section_reloc_link_order and
 773              bfd_symbol_reloc_link_order.  */
 774           struct bfd_link_order_reloc *p;
 775         } reloc;
 776     } u;
 777 };
 778
 779 /* A linker order of type bfd_section_reloc_link_order or
 780    bfd_symbol_reloc_link_order means to create a reloc against a
 781    section or symbol, respectively.  This is used to implement -Ur to
 782    generate relocs for the constructor tables.  The
 783    bfd_link_order_reloc structure describes the reloc that BFD should
 784    create.  It is similar to a arelent, but I didn't use arelent
 785    because the linker does not know anything about most symbols, and
 786    any asymbol structure it creates will be partially meaningless.
 787    This information could logically be in the bfd_link_order struct,
 788    but I didn't want to waste the space since these types of relocs
 789    are relatively rare.  */
 790
 791 struct bfd_link_order_reloc
 792 {
 793   /* Reloc type.  */
 794   bfd_reloc_code_real_type reloc;
 795
 796   union
 797     {
 798       /* For type bfd_section_reloc_link_order, this is the section
 799          the reloc should be against.  This must be a section in the
 800          output BFD, not any of the input BFDs.  */
 801       asection *section;
 802       /* For type bfd_symbol_reloc_link_order, this is the name of the
 803          symbol the reloc should be against.  */
 804       const char *name;
 805     } u;
 806
 807   /* Addend to use.  The object file should contain zero.  The BFD
 808      backend is responsible for filling in the contents of the object
 809      file correctly.  For some object file formats (e.g., COFF) the
 810      addend must be stored into in the object file, and for some
 811      (e.g., SPARC a.out) it is kept in the reloc.  */
 812   bfd_vma addend;
 813 };
 814
 815 /* Allocate a new link_order for a section.  */
 816 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 817
 818 /* These structures are used to describe version information for the
 819    ELF linker.  These structures could be manipulated entirely inside
 820    BFD, but it would be a pain.  Instead, the regular linker sets up
 821    these structures, and then passes them into BFD.  */
 822
 823 /* Glob pattern for a version.  */
 824
 825 struct bfd_elf_version_expr
 826 {
 827   /* Next glob pattern for this version.  */
 828   struct bfd_elf_version_expr *next;
 829   /* Glob pattern.  */
 830   const char *pattern;
 831   /* Set if pattern is not a glob.  */
 832   unsigned int literal : 1;
 833   /* Defined by ".symver".  */
 834   unsigned int symver : 1;
 835   /* Defined by version script.  */
 836   unsigned int script : 1;
 837   /* Pattern type.  */
 838 #define BFD_ELF_VERSION_C_TYPE          1
 839 #define BFD_ELF_VERSION_CXX_TYPE        2
 840 #define BFD_ELF_VERSION_JAVA_TYPE       4
 841   unsigned int mask : 3;
 842 };
 843
 844 struct bfd_elf_version_expr_head
 845 {
 846   /* List of all patterns, both wildcards and non-wildcards.  */
 847   struct bfd_elf_version_expr *list;
 848   /* Hash table for non-wildcards.  */
 849   void *htab;
 850   /* Remaining patterns.  */
 851   struct bfd_elf_version_expr *remaining;
 852   /* What kind of pattern types are present in list (bitmask).  */
 853   unsigned int mask;
 854 };
 855
 856 /* Version dependencies.  */
 857
 858 struct bfd_elf_version_deps
 859 {
 860   /* Next dependency for this version.  */
 861   struct bfd_elf_version_deps *next;
 862   /* The version which this version depends upon.  */
 863   struct bfd_elf_version_tree *version_needed;
 864 };
 865
 866 /* A node in the version tree.  */
 867
 868 struct bfd_elf_version_tree
 869 {
 870   /* Next version.  */
 871   struct bfd_elf_version_tree *next;
 872   /* Name of this version.  */
 873   const char *name;
 874   /* Version number.  */
 875   unsigned int vernum;
 876   /* Regular expressions for global symbols in this version.  */
 877   struct bfd_elf_version_expr_head globals;
 878   /* Regular expressions for local symbols in this version.  */
 879   struct bfd_elf_version_expr_head locals;
 880   /* List of versions which this version depends upon.  */
 881   struct bfd_elf_version_deps *deps;
 882   /* Index of the version name.  This is used within BFD.  */
 883   unsigned int name_indx;
 884   /* Whether this version tree was used.  This is used within BFD.  */
 885   int used;
 886   /* Matching hook.  */
 887   struct bfd_elf_version_expr *(*match)
 888     (struct bfd_elf_version_expr_head *head,
 889      struct bfd_elf_version_expr *prev, const char *sym);
 890 };
 891
 892 struct bfd_elf_dynamic_list
 893 {
 894   struct bfd_elf_version_expr_head head;
 895   struct bfd_elf_version_expr *(*match)
 896     (struct bfd_elf_version_expr_head *head,
 897      struct bfd_elf_version_expr *prev, const char *sym);
 898 };
 899
 900 #endif