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