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 /* Which symbols to strip during a link.  */
  28 enum bfd_link_strip
  29 {
  30   strip_none,           /* Don't strip any symbols.  */
  31   strip_debugger,       /* Strip debugging symbols.  */
  32   strip_some,           /* keep_hash is the list of symbols to keep.  */
  33   strip_all             /* Strip all symbols.  */
  34 };
  35
  36 /* Which local symbols to discard during a link.  This is irrelevant
  37    if strip_all is used.  */
  38 enum bfd_link_discard
  39 {
  40   discard_sec_merge,    /* Discard local temporary symbols in SEC_MERGE
  41                            sections.  */
  42   discard_none,         /* Don't discard any locals.  */
  43   discard_l,            /* Discard local temporary symbols.  */
  44   discard_all           /* Discard all locals.  */
  45 };
  46
  47 /* Describes the type of hash table entry structure being used.
  48    Different hash table structure have different fields and so
  49    support different linking features.  */
  50 enum bfd_link_hash_table_type
  51   {
  52     bfd_link_generic_hash_table,
  53     bfd_link_elf_hash_table
  54   };
  55 \f
  56 /* These are the possible types of an entry in the BFD link hash
  57    table.  */
  58
  59 enum bfd_link_hash_type
  60 {
  61   bfd_link_hash_new,            /* Symbol is new.  */
  62   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  63   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  64   bfd_link_hash_defined,        /* Symbol is defined.  */
  65   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  66   bfd_link_hash_common,         /* Symbol is common.  */
  67   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  68   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  69 };
  70
  71 enum bfd_link_common_skip_ar_symbols
  72 {
  73   bfd_link_common_skip_none,
  74   bfd_link_common_skip_text,
  75   bfd_link_common_skip_data,
  76   bfd_link_common_skip_all
  77 };
  78
  79 struct bfd_link_hash_common_entry
  80   {
  81     unsigned int alignment_power;       /* Alignment.  */
  82     asection *section;          /* Symbol section.  */
  83   };
  84
  85 /* The linking routines use a hash table which uses this structure for
  86    its elements.  */
  87
  88 struct bfd_link_hash_entry
  89 {
  90   /* Base hash table entry structure.  */
  91   struct bfd_hash_entry root;
  92
  93   /* Type of this entry.  */
  94   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
  95
  96   unsigned int non_ir_ref : 1;
  97
  98   /* A union of information depending upon the type.  */
  99   union
 100     {
 101       /* Nothing is kept for bfd_hash_new.  */
 102       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 103       struct
 104         {
 105           /* Undefined and common symbols are kept in a linked list through
 106              this field.  This field is present in all of the union element
 107              so that we don't need to remove entries from the list when we
 108              change their type.  Removing entries would either require the
 109              list to be doubly linked, which would waste more memory, or
 110              require a traversal.  When an undefined or common symbol is
 111              created, it should be added to this list, the head of which is in
 112              the link hash table itself.  As symbols are defined, they need
 113              not be removed from the list; anything which reads the list must
 114              doublecheck the symbol type.
 115
 116              Weak symbols are not kept on this list.
 117
 118              Defined and defweak symbols use this field as a reference marker.
 119              If the field is not NULL, or this structure is the tail of the
 120              undefined symbol list, the symbol has been referenced.  If the
 121              symbol is undefined and becomes defined, this field will
 122              automatically be non-NULL since the symbol will have been on the
 123              undefined symbol list.  */
 124           struct bfd_link_hash_entry *next;
 125           bfd *abfd;            /* BFD symbol was found in.  */
 126         } undef;
 127       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 128       struct
 129         {
 130           struct bfd_link_hash_entry *next;
 131           asection *section;    /* Symbol section.  */
 132           bfd_vma value;        /* Symbol value.  */
 133         } def;
 134       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 135       struct
 136         {
 137           struct bfd_link_hash_entry *next;
 138           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 139           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 140         } i;
 141       /* bfd_link_hash_common.  */
 142       struct
 143         {
 144           struct bfd_link_hash_entry *next;
 145           /* The linker needs to know three things about common
 146              symbols: the size, the alignment, and the section in
 147              which the symbol should be placed.  We store the size
 148              here, and we allocate a small structure to hold the
 149              section and the alignment.  The alignment is stored as a
 150              power of two.  We don't store all the information
 151              directly because we don't want to increase the size of
 152              the union; this structure is a major space user in the
 153              linker.  */
 154           struct bfd_link_hash_common_entry *p;
 155           bfd_size_type size;   /* Common symbol size.  */
 156         } c;
 157     } u;
 158 };
 159
 160 /* This is the link hash table.  It is a derived class of
 161    bfd_hash_table.  */
 162
 163 struct bfd_link_hash_table
 164 {
 165   /* The hash table itself.  */
 166   struct bfd_hash_table table;
 167   /* A linked list of undefined and common symbols, linked through the
 168      next field in the bfd_link_hash_entry structure.  */
 169   struct bfd_link_hash_entry *undefs;
 170   /* Entries are added to the tail of the undefs list.  */
 171   struct bfd_link_hash_entry *undefs_tail;
 172   /* The type of the link hash table.  */
 173   enum bfd_link_hash_table_type type;
 174 };
 175
 176 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 177    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 178    the real symbol.  */
 179 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 180   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 181    bfd_boolean copy, bfd_boolean follow);
 182
 183 /* Look up an entry in the main linker hash table if the symbol might
 184    be wrapped.  This should only be used for references to an
 185    undefined symbol, not for definitions of a symbol.  */
 186
 187 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 188   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 189    bfd_boolean, bfd_boolean);
 190
 191 /* Traverse a link hash table.  */
 192 extern void bfd_link_hash_traverse
 193   (struct bfd_link_hash_table *,
 194     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 195     void *);
 196
 197 /* Add an entry to the undefs list.  */
 198 extern void bfd_link_add_undef
 199   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 200
 201 /* Remove symbols from the undefs list that don't belong there.  */
 202 extern void bfd_link_repair_undef_list
 203   (struct bfd_link_hash_table *table);
 204
 205 /* Read symbols and cache symbol pointer array in outsymbols.  */
 206 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 207
 208 struct bfd_sym_chain
 209 {
 210   struct bfd_sym_chain *next;
 211   const char *name;
 212 };
 213 \f
 214 /* How to handle unresolved symbols.
 215    There are four possibilities which are enumerated below:  */
 216 enum report_method
 217 {
 218   /* This is the initial value when then link_info structure is created.
 219      It allows the various stages of the linker to determine whether they
 220      allowed to set the value.  */
 221   RM_NOT_YET_SET = 0,
 222   RM_IGNORE,
 223   RM_GENERATE_WARNING,
 224   RM_GENERATE_ERROR
 225 };
 226
 227 struct bfd_elf_dynamic_list;
 228
 229 /* This structure holds all the information needed to communicate
 230    between BFD and the linker when doing a link.  */
 231
 232 struct bfd_link_info
 233 {
 234   /* TRUE if BFD should generate a relocatable object file.  */
 235   unsigned int relocatable: 1;
 236
 237   /* TRUE if BFD should generate relocation information in the final
 238      executable.  */
 239   unsigned int emitrelocations: 1;
 240
 241   /* TRUE if BFD should generate a "task linked" object file,
 242      similar to relocatable but also with globals converted to
 243      statics.  */
 244   unsigned int task_link: 1;
 245
 246   /* TRUE if BFD should generate a shared object.  */
 247   unsigned int shared: 1;
 248
 249   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 250   unsigned int symbolic: 1;
 251
 252   /* TRUE if BFD should export all symbols in the dynamic symbol table
 253      of an executable, rather than only those used.  */
 254   unsigned int export_dynamic: 1;
 255
 256   /* TRUE if shared objects should be linked directly, not shared.  */
 257   unsigned int static_link: 1;
 258
 259   /* TRUE if the output file should be in a traditional format.  This
 260      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 261      on the output file, but may be checked when reading the input
 262      files.  */
 263   unsigned int traditional_format: 1;
 264
 265   /* TRUE if we want to produced optimized output files.  This might
 266      need much more time and therefore must be explicitly selected.  */
 267   unsigned int optimize: 1;
 268
 269   /* TRUE if ok to have multiple definition.  */
 270   unsigned int allow_multiple_definition: 1;
 271
 272   /* TRUE if ok to have version with no definition.  */
 273   unsigned int allow_undefined_version: 1;
 274
 275   /* TRUE if a default symbol version should be created and used for
 276      exported symbols.  */
 277   unsigned int create_default_symver: 1;
 278
 279   /* TRUE if a default symbol version should be created and used for
 280      imported symbols.  */
 281   unsigned int default_imported_symver: 1;
 282
 283   /* TRUE if symbols should be retained in memory, FALSE if they
 284      should be freed and reread.  */
 285   unsigned int keep_memory: 1;
 286
 287   /* TRUE if every symbol should be reported back via the notice
 288      callback.  */
 289   unsigned int notice_all: 1;
 290
 291   /* TRUE if executable should not contain copy relocs.
 292      Setting this true may result in a non-sharable text segment.  */
 293   unsigned int nocopyreloc: 1;
 294
 295   /* TRUE if the new ELF dynamic tags are enabled. */
 296   unsigned int new_dtags: 1;
 297
 298   /* TRUE if non-PLT relocs should be merged into one reloc section
 299      and sorted so that relocs against the same symbol come together.  */
 300   unsigned int combreloc: 1;
 301
 302   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 303      should be created.  */
 304   unsigned int eh_frame_hdr: 1;
 305
 306   /* TRUE if global symbols in discarded sections should be stripped.  */
 307   unsigned int strip_discarded: 1;
 308
 309   /* TRUE if generating a position independent executable.  */
 310   unsigned int pie: 1;
 311
 312   /* TRUE if generating an executable, position independent or not.  */
 313   unsigned int executable : 1;
 314
 315   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 316      flags.  */
 317   unsigned int execstack: 1;
 318
 319   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 320      flags.  */
 321   unsigned int noexecstack: 1;
 322
 323   /* TRUE if PT_GNU_RELRO segment should be created.  */
 324   unsigned int relro: 1;
 325
 326   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 327   unsigned int warn_shared_textrel: 1;
 328
 329   /* TRUE if we should warn alternate ELF machine code.  */
 330   unsigned int warn_alternate_em: 1;
 331
 332   /* TRUE if unreferenced sections should be removed.  */
 333   unsigned int gc_sections: 1;
 334
 335   /* TRUE if user shoudl be informed of removed unreferenced sections.  */
 336   unsigned int print_gc_sections: 1;
 337
 338   /* TRUE if .hash section should be created.  */
 339   unsigned int emit_hash: 1;
 340
 341   /* TRUE if .gnu.hash section should be created.  */
 342   unsigned int emit_gnu_hash: 1;
 343
 344   /* If TRUE reduce memory overheads, at the expense of speed. This will
 345      cause map file generation to use an O(N^2) algorithm and disable
 346      caching ELF symbol buffer.  */
 347   unsigned int reduce_memory_overheads: 1;
 348
 349   /* TRUE if all data symbols should be dynamic.  */
 350    unsigned int dynamic_data: 1;
 351
 352   /* TRUE if some symbols have to be dynamic, controlled by
 353      --dynamic-list command line options.  */
 354   unsigned int dynamic: 1;
 355
 356   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 357      linker created sections, TRUE if it should be omitted.  */
 358   unsigned int no_ld_generated_unwind_info: 1;
 359
 360   /* Non-NULL if .note.gnu.build-id section should be created.  */
 361   char *emit_note_gnu_build_id;
 362
 363   /* What to do with unresolved symbols in an object file.
 364      When producing executables the default is GENERATE_ERROR.
 365      When producing shared libraries the default is IGNORE.  The
 366      assumption with shared libraries is that the reference will be
 367      resolved at load/execution time.  */
 368   enum report_method unresolved_syms_in_objects;
 369
 370   /* What to do with unresolved symbols in a shared library.
 371      The same defaults apply.  */
 372   enum report_method unresolved_syms_in_shared_libs;
 373
 374   /* Which symbols to strip.  */
 375   enum bfd_link_strip strip;
 376
 377   /* Which local symbols to discard.  */
 378   enum bfd_link_discard discard;
 379
 380   /* Criteria for skipping symbols when determining
 381      whether to include an object from an archive. */
 382   enum bfd_link_common_skip_ar_symbols common_skip_ar_symbols;
 383
 384   /* Char that may appear as the first char of a symbol, but should be
 385      skipped (like symbol_leading_char) when looking up symbols in
 386      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 387   char wrap_char;
 388
 389   /* Separator between archive and filename in linker script filespecs.  */
 390   char path_separator;
 391
 392   /* Function callbacks.  */
 393   const struct bfd_link_callbacks *callbacks;
 394
 395   /* Hash table handled by BFD.  */
 396   struct bfd_link_hash_table *hash;
 397
 398   /* Hash table of symbols to keep.  This is NULL unless strip is
 399      strip_some.  */
 400   struct bfd_hash_table *keep_hash;
 401
 402   /* Hash table of symbols to report back via the notice callback.  If
 403      this is NULL, and notice_all is FALSE, then no symbols are
 404      reported back.  */
 405   struct bfd_hash_table *notice_hash;
 406
 407   /* Hash table of symbols which are being wrapped (the --wrap linker
 408      option).  If this is NULL, no symbols are being wrapped.  */
 409   struct bfd_hash_table *wrap_hash;
 410
 411   /* The output BFD.  */
 412   bfd *output_bfd;
 413
 414   /* The list of input BFD's involved in the link.  These are chained
 415      together via the link_next field.  */
 416   bfd *input_bfds;
 417   bfd **input_bfds_tail;
 418
 419   /* If a symbol should be created for each input BFD, this is section
 420      where those symbols should be placed.  It must be a section in
 421      the output BFD.  It may be NULL, in which case no such symbols
 422      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 423      linker command language.  */
 424   asection *create_object_symbols_section;
 425
 426   /* List of global symbol names that are starting points for marking
 427      sections against garbage collection.  */
 428   struct bfd_sym_chain *gc_sym_list;
 429
 430   /* If a base output file is wanted, then this points to it */
 431   void *base_file;
 432
 433   /* The function to call when the executable or shared object is
 434      loaded.  */
 435   const char *init_function;
 436
 437   /* The function to call when the executable or shared object is
 438      unloaded.  */
 439   const char *fini_function;
 440
 441   /* Number of relaxation passes.  Usually only one relaxation pass
 442      is needed.  But a backend can have as many relaxation passes as
 443      necessary.  During bfd_relax_section call, it is set to the
 444      current pass, starting from 0.  */
 445   int relax_pass;
 446
 447   /* Number of relaxation trips.  This number is incremented every
 448      time the relaxation pass is restarted due to a previous
 449      relaxation returning true in *AGAIN.  */
 450   int relax_trip;
 451
 452   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 453      should be generated/linked against.  Set to 1 if this feature
 454      is explicitly requested by the user, -1 if enabled by default.  */
 455   int pei386_auto_import;
 456
 457   /* Non-zero if runtime relocs for DATA items with non-zero addends
 458      in pei386 DLLs should be generated.  Set to 1 if this feature
 459      is explicitly requested by the user, -1 if enabled by default.  */
 460   int pei386_runtime_pseudo_reloc;
 461
 462   /* How many spare .dynamic DT_NULL entries should be added?  */
 463   unsigned int spare_dynamic_tags;
 464
 465   /* May be used to set DT_FLAGS for ELF. */
 466   bfd_vma flags;
 467
 468   /* May be used to set DT_FLAGS_1 for ELF. */
 469   bfd_vma flags_1;
 470
 471   /* Start and end of RELRO region.  */
 472   bfd_vma relro_start, relro_end;
 473
 474   /* List of symbols should be dynamic.  */
 475   struct bfd_elf_dynamic_list *dynamic_list;
 476 };
 477
 478 /* This structures holds a set of callback functions.  These are called
 479    by the BFD linker routines.  Except for the info functions, the first
 480    argument to each callback function is the bfd_link_info structure
 481    being used and each function returns a boolean value.  If the
 482    function returns FALSE, then the BFD function which called it should
 483    return with a failure indication.  */
 484
 485 struct bfd_link_callbacks
 486 {
 487   /* A function which is called when an object is added from an
 488      archive.  ABFD is the archive element being added.  NAME is the
 489      name of the symbol which caused the archive element to be pulled
 490      in.  This function may set *SUBSBFD to point to an alternative
 491      BFD from which symbols should in fact be added in place of the
 492      original BFD's symbols.  */
 493   bfd_boolean (*add_archive_element)
 494     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 495   /* A function which is called when a symbol is found with multiple
 496      definitions.  H is the symbol which is defined multiple times.
 497      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 498      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 499   bfd_boolean (*multiple_definition)
 500     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 501      bfd *nbfd, asection *nsec, bfd_vma nval);
 502   /* A function which is called when a common symbol is defined
 503      multiple times.  H is the symbol appearing multiple times.
 504      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 505      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 506      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 507      is the size of the new symbol.  */
 508   bfd_boolean (*multiple_common)
 509     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 510      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 511   /* A function which is called to add a symbol to a set.  ENTRY is
 512      the link hash table entry for the set itself (e.g.,
 513      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 514      the set when generating a relocatable file, and is also used to
 515      get the size of the entry when generating an executable file.
 516      ABFD, SEC and VALUE identify the value to add to the set.  */
 517   bfd_boolean (*add_to_set)
 518     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 519      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 520   /* A function which is called when the name of a g++ constructor or
 521      destructor is found.  This is only called by some object file
 522      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 523      destructor.  This will use BFD_RELOC_CTOR when generating a
 524      relocatable file.  NAME is the name of the symbol found.  ABFD,
 525      SECTION and VALUE are the value of the symbol.  */
 526   bfd_boolean (*constructor)
 527     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 528      bfd *abfd, asection *sec, bfd_vma value);
 529   /* A function which is called to issue a linker warning.  For
 530      example, this is called when there is a reference to a warning
 531      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 532      of the symbol which triggered the warning; it may be NULL if
 533      there is none.  ABFD, SECTION and ADDRESS identify the location
 534      which trigerred the warning; either ABFD or SECTION or both may
 535      be NULL if the location is not known.  */
 536   bfd_boolean (*warning)
 537     (struct bfd_link_info *, const char *warning, const char *symbol,
 538      bfd *abfd, asection *section, bfd_vma address);
 539   /* A function which is called when a relocation is attempted against
 540      an undefined symbol.  NAME is the symbol which is undefined.
 541      ABFD, SECTION and ADDRESS identify the location from which the
 542      reference is made. IS_FATAL indicates whether an undefined symbol is
 543      a fatal error or not. In some cases SECTION may be NULL.  */
 544   bfd_boolean (*undefined_symbol)
 545     (struct bfd_link_info *, const char *name, bfd *abfd,
 546      asection *section, bfd_vma address, bfd_boolean is_fatal);
 547   /* A function which is called when a reloc overflow occurs. ENTRY is
 548      the link hash table entry for the symbol the reloc is against.
 549      NAME is the name of the local symbol or section the reloc is
 550      against, RELOC_NAME is the name of the relocation, and ADDEND is
 551      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 552      location at which the overflow occurs; if this is the result of a
 553      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 554      ABFD will be NULL.  */
 555   bfd_boolean (*reloc_overflow)
 556     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 557      const char *name, const char *reloc_name, bfd_vma addend,
 558      bfd *abfd, asection *section, bfd_vma address);
 559   /* A function which is called when a dangerous reloc is performed.
 560      MESSAGE is an appropriate message.
 561      ABFD, SECTION and ADDRESS identify the location at which the
 562      problem occurred; if this is the result of a
 563      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 564      ABFD will be NULL.  */
 565   bfd_boolean (*reloc_dangerous)
 566     (struct bfd_link_info *, const char *message,
 567      bfd *abfd, asection *section, bfd_vma address);
 568   /* A function which is called when a reloc is found to be attached
 569      to a symbol which is not being written out.  NAME is the name of
 570      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 571      the reloc; if this is the result of a
 572      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 573      ABFD will be NULL.  */
 574   bfd_boolean (*unattached_reloc)
 575     (struct bfd_link_info *, const char *name,
 576      bfd *abfd, asection *section, bfd_vma address);
 577   /* A function which is called when a symbol in notice_hash is
 578      defined or referenced.  H is the symbol.  ABFD, SECTION and
 579      ADDRESS are the (new) value of the symbol.  If SECTION is
 580      bfd_und_section, this is a reference.  FLAGS are the symbol
 581      BSF_* flags.  STRING is the name of the symbol to indirect to if
 582      the sym is indirect, or the warning string if a warning sym.  */
 583   bfd_boolean (*notice)
 584     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 585      bfd *abfd, asection *section, bfd_vma address, flagword flags,
 586      const char *string);
 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