include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
   3    2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
   4    Free Software Foundation, Inc.
   5    Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
   6
   7    This file is part of BFD, the Binary File Descriptor library.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  22    MA 02110-1301, USA.  */
  23
  24 #ifndef BFDLINK_H
  25 #define BFDLINK_H
  26
  27 #if (__GNUC__ * 1000 + __GNUC_MINOR__ > 2000)
  28 #define ENUM_BITFIELD(TYPE) __extension__ enum TYPE
  29 #else
  30 #define ENUM_BITFIELD(TYPE) unsigned int
  31 #endif
  32
  33 /* Which symbols to strip during a link.  */
  34 enum bfd_link_strip
  35 {
  36   strip_none,           /* Don't strip any symbols.  */
  37   strip_debugger,       /* Strip debugging symbols.  */
  38   strip_some,           /* keep_hash is the list of symbols to keep.  */
  39   strip_all             /* Strip all symbols.  */
  40 };
  41
  42 /* Which local symbols to discard during a link.  This is irrelevant
  43    if strip_all is used.  */
  44 enum bfd_link_discard
  45 {
  46   discard_sec_merge,    /* Discard local temporary symbols in SEC_MERGE
  47                            sections.  */
  48   discard_none,         /* Don't discard any locals.  */
  49   discard_l,            /* Discard local temporary symbols.  */
  50   discard_all           /* Discard all locals.  */
  51 };
  52
  53 /* Describes the type of hash table entry structure being used.
  54    Different hash table structure have different fields and so
  55    support different linking features.  */
  56 enum bfd_link_hash_table_type
  57   {
  58     bfd_link_generic_hash_table,
  59     bfd_link_elf_hash_table
  60   };
  61 \f
  62 /* These are the possible types of an entry in the BFD link hash
  63    table.  */
  64
  65 enum bfd_link_hash_type
  66 {
  67   bfd_link_hash_new,            /* Symbol is new.  */
  68   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  69   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  70   bfd_link_hash_defined,        /* Symbol is defined.  */
  71   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  72   bfd_link_hash_common,         /* Symbol is common.  */
  73   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  74   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  75 };
  76
  77 enum bfd_link_common_skip_ar_symbols
  78 {
  79   bfd_link_common_skip_none,
  80   bfd_link_common_skip_text,
  81   bfd_link_common_skip_data,
  82   bfd_link_common_skip_all
  83 };
  84
  85 struct bfd_link_hash_common_entry
  86   {
  87     unsigned int alignment_power;       /* Alignment.  */
  88     asection *section;          /* Symbol section.  */
  89   };
  90
  91 /* The linking routines use a hash table which uses this structure for
  92    its elements.  */
  93
  94 struct bfd_link_hash_entry
  95 {
  96   /* Base hash table entry structure.  */
  97   struct bfd_hash_entry root;
  98
  99   /* Type of this entry.  */
 100   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
 101
 102   unsigned int non_ir_ref : 1;
 103
 104   /* A union of information depending upon the type.  */
 105   union
 106     {
 107       /* Nothing is kept for bfd_hash_new.  */
 108       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 109       struct
 110         {
 111           /* Undefined and common symbols are kept in a linked list through
 112              this field.  This field is present in all of the union element
 113              so that we don't need to remove entries from the list when we
 114              change their type.  Removing entries would either require the
 115              list to be doubly linked, which would waste more memory, or
 116              require a traversal.  When an undefined or common symbol is
 117              created, it should be added to this list, the head of which is in
 118              the link hash table itself.  As symbols are defined, they need
 119              not be removed from the list; anything which reads the list must
 120              doublecheck the symbol type.
 121
 122              Weak symbols are not kept on this list.
 123
 124              Defined and defweak symbols use this field as a reference marker.
 125              If the field is not NULL, or this structure is the tail of the
 126              undefined symbol list, the symbol has been referenced.  If the
 127              symbol is undefined and becomes defined, this field will
 128              automatically be non-NULL since the symbol will have been on the
 129              undefined symbol list.  */
 130           struct bfd_link_hash_entry *next;
 131           bfd *abfd;            /* BFD symbol was found in.  */
 132           bfd *weak;            /* BFD weak symbol was found in.  */
 133         } undef;
 134       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 135       struct
 136         {
 137           struct bfd_link_hash_entry *next;
 138           asection *section;    /* Symbol section.  */
 139           bfd_vma value;        /* Symbol value.  */
 140         } def;
 141       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 142       struct
 143         {
 144           struct bfd_link_hash_entry *next;
 145           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 146           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 147         } i;
 148       /* bfd_link_hash_common.  */
 149       struct
 150         {
 151           struct bfd_link_hash_entry *next;
 152           /* The linker needs to know three things about common
 153              symbols: the size, the alignment, and the section in
 154              which the symbol should be placed.  We store the size
 155              here, and we allocate a small structure to hold the
 156              section and the alignment.  The alignment is stored as a
 157              power of two.  We don't store all the information
 158              directly because we don't want to increase the size of
 159              the union; this structure is a major space user in the
 160              linker.  */
 161           struct bfd_link_hash_common_entry *p;
 162           bfd_size_type size;   /* Common symbol size.  */
 163         } c;
 164     } u;
 165 };
 166
 167 /* This is the link hash table.  It is a derived class of
 168    bfd_hash_table.  */
 169
 170 struct bfd_link_hash_table
 171 {
 172   /* The hash table itself.  */
 173   struct bfd_hash_table table;
 174   /* A linked list of undefined and common symbols, linked through the
 175      next field in the bfd_link_hash_entry structure.  */
 176   struct bfd_link_hash_entry *undefs;
 177   /* Entries are added to the tail of the undefs list.  */
 178   struct bfd_link_hash_entry *undefs_tail;
 179   /* The type of the link hash table.  */
 180   enum bfd_link_hash_table_type type;
 181 };
 182
 183 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 184    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 185    the real symbol.  */
 186 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 187   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 188    bfd_boolean copy, bfd_boolean follow);
 189
 190 /* Look up an entry in the main linker hash table if the symbol might
 191    be wrapped.  This should only be used for references to an
 192    undefined symbol, not for definitions of a symbol.  */
 193
 194 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 195   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 196    bfd_boolean, bfd_boolean);
 197
 198 /* Traverse a link hash table.  */
 199 extern void bfd_link_hash_traverse
 200   (struct bfd_link_hash_table *,
 201     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 202     void *);
 203
 204 /* Add an entry to the undefs list.  */
 205 extern void bfd_link_add_undef
 206   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 207
 208 /* Remove symbols from the undefs list that don't belong there.  */
 209 extern void bfd_link_repair_undef_list
 210   (struct bfd_link_hash_table *table);
 211
 212 /* Read symbols and cache symbol pointer array in outsymbols.  */
 213 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 214
 215 struct bfd_sym_chain
 216 {
 217   struct bfd_sym_chain *next;
 218   const char *name;
 219 };
 220 \f
 221 /* How to handle unresolved symbols.
 222    There are four possibilities which are enumerated below:  */
 223 enum report_method
 224 {
 225   /* This is the initial value when then link_info structure is created.
 226      It allows the various stages of the linker to determine whether they
 227      allowed to set the value.  */
 228   RM_NOT_YET_SET = 0,
 229   RM_IGNORE,
 230   RM_GENERATE_WARNING,
 231   RM_GENERATE_ERROR
 232 };
 233
 234 struct bfd_elf_dynamic_list;
 235
 236 /* This structure holds all the information needed to communicate
 237    between BFD and the linker when doing a link.  */
 238
 239 struct bfd_link_info
 240 {
 241   /* TRUE if BFD should generate a relocatable object file.  */
 242   unsigned int relocatable: 1;
 243
 244   /* TRUE if BFD should generate relocation information in the final
 245      executable.  */
 246   unsigned int emitrelocations: 1;
 247
 248   /* TRUE if BFD should generate a "task linked" object file,
 249      similar to relocatable but also with globals converted to
 250      statics.  */
 251   unsigned int task_link: 1;
 252
 253   /* TRUE if BFD should generate a shared object.  */
 254   unsigned int shared: 1;
 255
 256   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 257   unsigned int symbolic: 1;
 258
 259   /* TRUE if BFD should export all symbols in the dynamic symbol table
 260      of an executable, rather than only those used.  */
 261   unsigned int export_dynamic: 1;
 262
 263   /* TRUE if shared objects should be linked directly, not shared.  */
 264   unsigned int static_link: 1;
 265
 266   /* TRUE if the output file should be in a traditional format.  This
 267      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 268      on the output file, but may be checked when reading the input
 269      files.  */
 270   unsigned int traditional_format: 1;
 271
 272   /* TRUE if we want to produced optimized output files.  This might
 273      need much more time and therefore must be explicitly selected.  */
 274   unsigned int optimize: 1;
 275
 276   /* TRUE if ok to have multiple definition.  */
 277   unsigned int allow_multiple_definition: 1;
 278
 279   /* TRUE if ok to have version with no definition.  */
 280   unsigned int allow_undefined_version: 1;
 281
 282   /* TRUE if a default symbol version should be created and used for
 283      exported symbols.  */
 284   unsigned int create_default_symver: 1;
 285
 286   /* TRUE if a default symbol version should be created and used for
 287      imported symbols.  */
 288   unsigned int default_imported_symver: 1;
 289
 290   /* TRUE if symbols should be retained in memory, FALSE if they
 291      should be freed and reread.  */
 292   unsigned int keep_memory: 1;
 293
 294   /* TRUE if every symbol should be reported back via the notice
 295      callback.  */
 296   unsigned int notice_all: 1;
 297
 298   /* TRUE if executable should not contain copy relocs.
 299      Setting this true may result in a non-sharable text segment.  */
 300   unsigned int nocopyreloc: 1;
 301
 302   /* TRUE if the new ELF dynamic tags are enabled. */
 303   unsigned int new_dtags: 1;
 304
 305   /* TRUE if non-PLT relocs should be merged into one reloc section
 306      and sorted so that relocs against the same symbol come together.  */
 307   unsigned int combreloc: 1;
 308
 309   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 310      should be created.  */
 311   unsigned int eh_frame_hdr: 1;
 312
 313   /* TRUE if global symbols in discarded sections should be stripped.  */
 314   unsigned int strip_discarded: 1;
 315
 316   /* TRUE if generating a position independent executable.  */
 317   unsigned int pie: 1;
 318
 319   /* TRUE if generating an executable, position independent or not.  */
 320   unsigned int executable : 1;
 321
 322   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 323      flags.  */
 324   unsigned int execstack: 1;
 325
 326   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 327      flags.  */
 328   unsigned int noexecstack: 1;
 329
 330   /* TRUE if PT_GNU_RELRO segment should be created.  */
 331   unsigned int relro: 1;
 332
 333   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 334   unsigned int warn_shared_textrel: 1;
 335
 336   /* TRUE if we should warn alternate ELF machine code.  */
 337   unsigned int warn_alternate_em: 1;
 338
 339   /* TRUE if unreferenced sections should be removed.  */
 340   unsigned int gc_sections: 1;
 341
 342   /* TRUE if user shoudl be informed of removed unreferenced sections.  */
 343   unsigned int print_gc_sections: 1;
 344
 345   /* TRUE if .hash section should be created.  */
 346   unsigned int emit_hash: 1;
 347
 348   /* TRUE if .gnu.hash section should be created.  */
 349   unsigned int emit_gnu_hash: 1;
 350
 351   /* If TRUE reduce memory overheads, at the expense of speed. This will
 352      cause map file generation to use an O(N^2) algorithm and disable
 353      caching ELF symbol buffer.  */
 354   unsigned int reduce_memory_overheads: 1;
 355
 356   /* TRUE if all data symbols should be dynamic.  */
 357    unsigned int dynamic_data: 1;
 358
 359   /* TRUE if some symbols have to be dynamic, controlled by
 360      --dynamic-list command line options.  */
 361   unsigned int dynamic: 1;
 362
 363   /* Non-NULL if .note.gnu.build-id section should be created.  */
 364   char *emit_note_gnu_build_id;
 365
 366   /* What to do with unresolved symbols in an object file.
 367      When producing executables the default is GENERATE_ERROR.
 368      When producing shared libraries the default is IGNORE.  The
 369      assumption with shared libraries is that the reference will be
 370      resolved at load/execution time.  */
 371   enum report_method unresolved_syms_in_objects;
 372
 373   /* What to do with unresolved symbols in a shared library.
 374      The same defaults apply.  */
 375   enum report_method unresolved_syms_in_shared_libs;
 376
 377   /* Which symbols to strip.  */
 378   enum bfd_link_strip strip;
 379
 380   /* Which local symbols to discard.  */
 381   enum bfd_link_discard discard;
 382
 383   /* Criteria for skipping symbols when determining
 384      whether to include an object from an archive. */
 385   enum bfd_link_common_skip_ar_symbols common_skip_ar_symbols;
 386
 387   /* Char that may appear as the first char of a symbol, but should be
 388      skipped (like symbol_leading_char) when looking up symbols in
 389      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 390   char wrap_char;
 391
 392   /* Separator between archive and filename in linker script filespecs.  */
 393   char path_separator;
 394
 395   /* Function callbacks.  */
 396   const struct bfd_link_callbacks *callbacks;
 397
 398   /* Hash table handled by BFD.  */
 399   struct bfd_link_hash_table *hash;
 400
 401   /* Hash table of symbols to keep.  This is NULL unless strip is
 402      strip_some.  */
 403   struct bfd_hash_table *keep_hash;
 404
 405   /* Hash table of symbols to report back via the notice callback.  If
 406      this is NULL, and notice_all is FALSE, then no symbols are
 407      reported back.  */
 408   struct bfd_hash_table *notice_hash;
 409
 410   /* Hash table of symbols which are being wrapped (the --wrap linker
 411      option).  If this is NULL, no symbols are being wrapped.  */
 412   struct bfd_hash_table *wrap_hash;
 413
 414   /* The output BFD.  */
 415   bfd *output_bfd;
 416
 417   /* The list of input BFD's involved in the link.  These are chained
 418      together via the link_next field.  */
 419   bfd *input_bfds;
 420   bfd **input_bfds_tail;
 421
 422   /* If a symbol should be created for each input BFD, this is section
 423      where those symbols should be placed.  It must be a section in
 424      the output BFD.  It may be NULL, in which case no such symbols
 425      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 426      linker command language.  */
 427   asection *create_object_symbols_section;
 428
 429   /* List of global symbol names that are starting points for marking
 430      sections against garbage collection.  */
 431   struct bfd_sym_chain *gc_sym_list;
 432
 433   /* If a base output file is wanted, then this points to it */
 434   void *base_file;
 435
 436   /* The function to call when the executable or shared object is
 437      loaded.  */
 438   const char *init_function;
 439
 440   /* The function to call when the executable or shared object is
 441      unloaded.  */
 442   const char *fini_function;
 443
 444   /* Number of relaxation passes.  Usually only one relaxation pass
 445      is needed.  But a backend can have as many relaxation passes as
 446      necessary.  During bfd_relax_section call, it is set to the
 447      current pass, starting from 0.  */
 448   int relax_pass;
 449
 450   /* Number of relaxation trips.  This number is incremented every
 451      time the relaxation pass is restarted due to a previous
 452      relaxation returning true in *AGAIN.  */
 453   int relax_trip;
 454
 455   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 456      should be generated/linked against.  Set to 1 if this feature
 457      is explicitly requested by the user, -1 if enabled by default.  */
 458   int pei386_auto_import;
 459
 460   /* Non-zero if runtime relocs for DATA items with non-zero addends
 461      in pei386 DLLs should be generated.  Set to 1 if this feature
 462      is explicitly requested by the user, -1 if enabled by default.  */
 463   int pei386_runtime_pseudo_reloc;
 464
 465   /* How many spare .dynamic DT_NULL entries should be added?  */
 466   unsigned int spare_dynamic_tags;
 467
 468   /* May be used to set DT_FLAGS for ELF. */
 469   bfd_vma flags;
 470
 471   /* May be used to set DT_FLAGS_1 for ELF. */
 472   bfd_vma flags_1;
 473
 474   /* Start and end of RELRO region.  */
 475   bfd_vma relro_start, relro_end;
 476
 477   /* List of symbols should be dynamic.  */
 478   struct bfd_elf_dynamic_list *dynamic_list;
 479 };
 480
 481 /* This structures holds a set of callback functions.  These are called
 482    by the BFD linker routines.  Except for the info functions, the first
 483    argument to each callback function is the bfd_link_info structure
 484    being used and each function returns a boolean value.  If the
 485    function returns FALSE, then the BFD function which called it should
 486    return with a failure indication.  */
 487
 488 struct bfd_link_callbacks
 489 {
 490   /* A function which is called when an object is added from an
 491      archive.  ABFD is the archive element being added.  NAME is the
 492      name of the symbol which caused the archive element to be pulled
 493      in.  This function may set *SUBSBFD to point to an alternative
 494      BFD from which symbols should in fact be added in place of the
 495      original BFD's symbols.  */
 496   bfd_boolean (*add_archive_element)
 497     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 498   /* A function which is called when a symbol is found with multiple
 499      definitions.  H is the symbol which is defined multiple times.
 500      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 501      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 502   bfd_boolean (*multiple_definition)
 503     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 504      bfd *nbfd, asection *nsec, bfd_vma nval);
 505   /* A function which is called when a common symbol is defined
 506      multiple times.  H is the symbol appearing multiple times.
 507      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 508      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 509      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 510      is the size of the new symbol.  */
 511   bfd_boolean (*multiple_common)
 512     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 513      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 514   /* A function which is called to add a symbol to a set.  ENTRY is
 515      the link hash table entry for the set itself (e.g.,
 516      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 517      the set when generating a relocatable file, and is also used to
 518      get the size of the entry when generating an executable file.
 519      ABFD, SEC and VALUE identify the value to add to the set.  */
 520   bfd_boolean (*add_to_set)
 521     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 522      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 523   /* A function which is called when the name of a g++ constructor or
 524      destructor is found.  This is only called by some object file
 525      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 526      destructor.  This will use BFD_RELOC_CTOR when generating a
 527      relocatable file.  NAME is the name of the symbol found.  ABFD,
 528      SECTION and VALUE are the value of the symbol.  */
 529   bfd_boolean (*constructor)
 530     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 531      bfd *abfd, asection *sec, bfd_vma value);
 532   /* A function which is called to issue a linker warning.  For
 533      example, this is called when there is a reference to a warning
 534      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 535      of the symbol which triggered the warning; it may be NULL if
 536      there is none.  ABFD, SECTION and ADDRESS identify the location
 537      which trigerred the warning; either ABFD or SECTION or both may
 538      be NULL if the location is not known.  */
 539   bfd_boolean (*warning)
 540     (struct bfd_link_info *, const char *warning, const char *symbol,
 541      bfd *abfd, asection *section, bfd_vma address);
 542   /* A function which is called when a relocation is attempted against
 543      an undefined symbol.  NAME is the symbol which is undefined.
 544      ABFD, SECTION and ADDRESS identify the location from which the
 545      reference is made. IS_FATAL indicates whether an undefined symbol is
 546      a fatal error or not. In some cases SECTION may be NULL.  */
 547   bfd_boolean (*undefined_symbol)
 548     (struct bfd_link_info *, const char *name, bfd *abfd,
 549      asection *section, bfd_vma address, bfd_boolean is_fatal);
 550   /* A function which is called when a reloc overflow occurs. ENTRY is
 551      the link hash table entry for the symbol the reloc is against.
 552      NAME is the name of the local symbol or section the reloc is
 553      against, RELOC_NAME is the name of the relocation, and ADDEND is
 554      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 555      location at which the overflow occurs; if this is the result of a
 556      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 557      ABFD will be NULL.  */
 558   bfd_boolean (*reloc_overflow)
 559     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 560      const char *name, const char *reloc_name, bfd_vma addend,
 561      bfd *abfd, asection *section, bfd_vma address);
 562   /* A function which is called when a dangerous reloc is performed.
 563      MESSAGE is an appropriate message.
 564      ABFD, SECTION and ADDRESS identify the location at which the
 565      problem occurred; if this is the result of a
 566      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 567      ABFD will be NULL.  */
 568   bfd_boolean (*reloc_dangerous)
 569     (struct bfd_link_info *, const char *message,
 570      bfd *abfd, asection *section, bfd_vma address);
 571   /* A function which is called when a reloc is found to be attached
 572      to a symbol which is not being written out.  NAME is the name of
 573      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 574      the reloc; if this is the result of a
 575      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 576      ABFD will be NULL.  */
 577   bfd_boolean (*unattached_reloc)
 578     (struct bfd_link_info *, const char *name,
 579      bfd *abfd, asection *section, bfd_vma address);
 580   /* A function which is called when a symbol in notice_hash is
 581      defined or referenced.  H is the symbol.  ABFD, SECTION and
 582      ADDRESS are the (new) value of the symbol.  If SECTION is
 583      bfd_und_section, this is a reference.  */
 584   bfd_boolean (*notice)
 585     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 586      bfd *abfd, asection *section, bfd_vma address);
 587   /* Error or warning link info message.  */
 588   void (*einfo)
 589     (const char *fmt, ...);
 590   /* General link info message.  */
 591   void (*info)
 592     (const char *fmt, ...);
 593   /* Message to be printed in linker map file.  */
 594   void (*minfo)
 595     (const char *fmt, ...);
 596   /* This callback provides a chance for users of the BFD library to
 597      override its decision about whether to place two adjacent sections
 598      into the same segment.  */
 599   bfd_boolean (*override_segment_assignment)
 600     (struct bfd_link_info *, bfd * abfd,
 601      asection * current_section, asection * previous_section,
 602      bfd_boolean new_segment);
 603 };
 604 \f
 605 /* The linker builds link_order structures which tell the code how to
 606    include input data in the output file.  */
 607
 608 /* These are the types of link_order structures.  */
 609
 610 enum bfd_link_order_type
 611 {
 612   bfd_undefined_link_order,     /* Undefined.  */
 613   bfd_indirect_link_order,      /* Built from a section.  */
 614   bfd_data_link_order,          /* Set to explicit data.  */
 615   bfd_section_reloc_link_order, /* Relocate against a section.  */
 616   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 617 };
 618
 619 /* This is the link_order structure itself.  These form a chain
 620    attached to the output section whose contents they are describing.  */
 621
 622 struct bfd_link_order
 623 {
 624   /* Next link_order in chain.  */
 625   struct bfd_link_order *next;
 626   /* Type of link_order.  */
 627   enum bfd_link_order_type type;
 628   /* Offset within output section.  */
 629   bfd_vma offset;
 630   /* Size within output section.  */
 631   bfd_size_type size;
 632   /* Type specific information.  */
 633   union
 634     {
 635       struct
 636         {
 637           /* Section to include.  If this is used, then
 638              section->output_section must be the section the
 639              link_order is attached to, section->output_offset must
 640              equal the link_order offset field, and section->size
 641              must equal the link_order size field.  Maybe these
 642              restrictions should be relaxed someday.  */
 643           asection *section;
 644         } indirect;
 645       struct
 646         {
 647           /* Size of contents, or zero when contents size == size
 648              within output section.
 649              A non-zero value allows filling of the output section
 650              with an arbitrary repeated pattern.  */
 651           unsigned int size;
 652           /* Data to put into file.  */
 653           bfd_byte *contents;
 654         } data;
 655       struct
 656         {
 657           /* Description of reloc to generate.  Used for
 658              bfd_section_reloc_link_order and
 659              bfd_symbol_reloc_link_order.  */
 660           struct bfd_link_order_reloc *p;
 661         } reloc;
 662     } u;
 663 };
 664
 665 /* A linker order of type bfd_section_reloc_link_order or
 666    bfd_symbol_reloc_link_order means to create a reloc against a
 667    section or symbol, respectively.  This is used to implement -Ur to
 668    generate relocs for the constructor tables.  The
 669    bfd_link_order_reloc structure describes the reloc that BFD should
 670    create.  It is similar to a arelent, but I didn't use arelent
 671    because the linker does not know anything about most symbols, and
 672    any asymbol structure it creates will be partially meaningless.
 673    This information could logically be in the bfd_link_order struct,
 674    but I didn't want to waste the space since these types of relocs
 675    are relatively rare.  */
 676
 677 struct bfd_link_order_reloc
 678 {
 679   /* Reloc type.  */
 680   bfd_reloc_code_real_type reloc;
 681
 682   union
 683     {
 684       /* For type bfd_section_reloc_link_order, this is the section
 685          the reloc should be against.  This must be a section in the
 686          output BFD, not any of the input BFDs.  */
 687       asection *section;
 688       /* For type bfd_symbol_reloc_link_order, this is the name of the
 689          symbol the reloc should be against.  */
 690       const char *name;
 691     } u;
 692
 693   /* Addend to use.  The object file should contain zero.  The BFD
 694      backend is responsible for filling in the contents of the object
 695      file correctly.  For some object file formats (e.g., COFF) the
 696      addend must be stored into in the object file, and for some
 697      (e.g., SPARC a.out) it is kept in the reloc.  */
 698   bfd_vma addend;
 699 };
 700
 701 /* Allocate a new link_order for a section.  */
 702 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 703
 704 /* These structures are used to describe version information for the
 705    ELF linker.  These structures could be manipulated entirely inside
 706    BFD, but it would be a pain.  Instead, the regular linker sets up
 707    these structures, and then passes them into BFD.  */
 708
 709 /* Glob pattern for a version.  */
 710
 711 struct bfd_elf_version_expr
 712 {
 713   /* Next glob pattern for this version.  */
 714   struct bfd_elf_version_expr *next;
 715   /* Glob pattern.  */
 716   const char *pattern;
 717   /* Set if pattern is not a glob.  */
 718   unsigned int literal : 1;
 719   /* Defined by ".symver".  */
 720   unsigned int symver : 1;
 721   /* Defined by version script.  */
 722   unsigned int script : 1;
 723   /* Pattern type.  */
 724 #define BFD_ELF_VERSION_C_TYPE          1
 725 #define BFD_ELF_VERSION_CXX_TYPE        2
 726 #define BFD_ELF_VERSION_JAVA_TYPE       4
 727   unsigned int mask : 3;
 728 };
 729
 730 struct bfd_elf_version_expr_head
 731 {
 732   /* List of all patterns, both wildcards and non-wildcards.  */
 733   struct bfd_elf_version_expr *list;
 734   /* Hash table for non-wildcards.  */
 735   void *htab;
 736   /* Remaining patterns.  */
 737   struct bfd_elf_version_expr *remaining;
 738   /* What kind of pattern types are present in list (bitmask).  */
 739   unsigned int mask;
 740 };
 741
 742 /* Version dependencies.  */
 743
 744 struct bfd_elf_version_deps
 745 {
 746   /* Next dependency for this version.  */
 747   struct bfd_elf_version_deps *next;
 748   /* The version which this version depends upon.  */
 749   struct bfd_elf_version_tree *version_needed;
 750 };
 751
 752 /* A node in the version tree.  */
 753
 754 struct bfd_elf_version_tree
 755 {
 756   /* Next version.  */
 757   struct bfd_elf_version_tree *next;
 758   /* Name of this version.  */
 759   const char *name;
 760   /* Version number.  */
 761   unsigned int vernum;
 762   /* Regular expressions for global symbols in this version.  */
 763   struct bfd_elf_version_expr_head globals;
 764   /* Regular expressions for local symbols in this version.  */
 765   struct bfd_elf_version_expr_head locals;
 766   /* List of versions which this version depends upon.  */
 767   struct bfd_elf_version_deps *deps;
 768   /* Index of the version name.  This is used within BFD.  */
 769   unsigned int name_indx;
 770   /* Whether this version tree was used.  This is used within BFD.  */
 771   int used;
 772   /* Matching hook.  */
 773   struct bfd_elf_version_expr *(*match)
 774     (struct bfd_elf_version_expr_head *head,
 775      struct bfd_elf_version_expr *prev, const char *sym);
 776 };
 777
 778 struct bfd_elf_dynamic_list
 779 {
 780   struct bfd_elf_version_expr_head head;
 781   struct bfd_elf_version_expr *(*match)
 782     (struct bfd_elf_version_expr_head *head,
 783      struct bfd_elf_version_expr *prev, const char *sym);
 784 };
 785
 786 #endif