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