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 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_aymbols
  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 /* The linking routines use a hash table which uses this structure for
  79    its elements.  */
  80
  81 struct bfd_link_hash_entry
  82 {
  83   /* Base hash table entry structure.  */
  84   struct bfd_hash_entry root;
  85
  86   /* Type of this entry.  */
  87   enum bfd_link_hash_type type;
  88
  89   /* A union of information depending upon the type.  */
  90   union
  91     {
  92       /* Nothing is kept for bfd_hash_new.  */
  93       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
  94       struct
  95         {
  96           /* Undefined and common symbols are kept in a linked list through
  97              this field.  This field is present in all of the union element
  98              so that we don't need to remove entries from the list when we
  99              change their type.  Removing entries would either require the
 100              list to be doubly linked, which would waste more memory, or
 101              require a traversal.  When an undefined or common symbol is
 102              created, it should be added to this list, the head of which is in
 103              the link hash table itself.  As symbols are defined, they need
 104              not be removed from the list; anything which reads the list must
 105              doublecheck the symbol type.
 106
 107              Weak symbols are not kept on this list.
 108
 109              Defined and defweak symbols use this field as a reference marker.
 110              If the field is not NULL, or this structure is the tail of the
 111              undefined symbol list, the symbol has been referenced.  If the
 112              symbol is undefined and becomes defined, this field will
 113              automatically be non-NULL since the symbol will have been on the
 114              undefined symbol list.  */
 115           struct bfd_link_hash_entry *next;
 116           bfd *abfd;            /* BFD symbol was found in.  */
 117           bfd *weak;            /* BFD weak symbol was found in.  */
 118         } undef;
 119       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 120       struct
 121         {
 122           struct bfd_link_hash_entry *next;
 123           asection *section;    /* Symbol section.  */
 124           bfd_vma value;        /* Symbol value.  */
 125         } def;
 126       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 127       struct
 128         {
 129           struct bfd_link_hash_entry *next;
 130           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 131           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 132         } i;
 133       /* bfd_link_hash_common.  */
 134       struct
 135         {
 136           struct bfd_link_hash_entry *next;
 137           /* The linker needs to know three things about common
 138              symbols: the size, the alignment, and the section in
 139              which the symbol should be placed.  We store the size
 140              here, and we allocate a small structure to hold the
 141              section and the alignment.  The alignment is stored as a
 142              power of two.  We don't store all the information
 143              directly because we don't want to increase the size of
 144              the union; this structure is a major space user in the
 145              linker.  */
 146           struct bfd_link_hash_common_entry
 147             {
 148               unsigned int alignment_power;     /* Alignment.  */
 149               asection *section;                /* Symbol section.  */
 150             } *p;
 151           bfd_size_type size;   /* Common symbol size.  */
 152         } c;
 153     } u;
 154 };
 155
 156 /* This is the link hash table.  It is a derived class of
 157    bfd_hash_table.  */
 158
 159 struct bfd_link_hash_table
 160 {
 161   /* The hash table itself.  */
 162   struct bfd_hash_table table;
 163   /* The back end which created this hash table.  This indicates the
 164      type of the entries in the hash table, which is sometimes
 165      important information when linking object files of different
 166      types together.  */
 167   const bfd_target *creator;
 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 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 unreferenced sections should be removed.  */
 328   unsigned int gc_sections: 1;
 329
 330   /* TRUE if user shoudl be informed of removed unreferenced sections.  */
 331   unsigned int print_gc_sections: 1;
 332
 333   /* TRUE if .hash section should be created.  */
 334   unsigned int emit_hash: 1;
 335
 336   /* TRUE if .gnu.hash section should be created.  */
 337   unsigned int emit_gnu_hash: 1;
 338
 339   /* If TRUE reduce memory overheads, at the expense of speed. This will
 340      cause map file generation to use an O(N^2) algorithm and disable
 341      caching ELF symbol buffer.  */
 342   unsigned int reduce_memory_overheads: 1;
 343
 344   /* TRUE if all data symbols should be dynamic.  */
 345    unsigned int dynamic_data: 1;
 346
 347   /* TRUE if some symbols have to be dynamic, controlled by
 348      --dynamic-list command line options.  */
 349   unsigned int dynamic: 1;
 350
 351   /* Non-NULL if .note.gnu.build-id section should be created.  */
 352   char *emit_note_gnu_build_id;
 353
 354   /* What to do with unresolved symbols in an object file.
 355      When producing executables the default is GENERATE_ERROR.
 356      When producing shared libraries the default is IGNORE.  The
 357      assumption with shared libraries is that the reference will be
 358      resolved at load/execution time.  */
 359   enum report_method unresolved_syms_in_objects;
 360
 361   /* What to do with unresolved symbols in a shared library.
 362      The same defaults apply.  */
 363   enum report_method unresolved_syms_in_shared_libs;
 364
 365   /* Which symbols to strip.  */
 366   enum bfd_link_strip strip;
 367
 368   /* Which local symbols to discard.  */
 369   enum bfd_link_discard discard;
 370
 371   /* Criteria for skipping symbols when detemining
 372      whether to include an object from an archive. */
 373   enum bfd_link_common_skip_ar_aymbols common_skip_ar_aymbols;
 374
 375   /* Char that may appear as the first char of a symbol, but should be
 376      skipped (like symbol_leading_char) when looking up symbols in
 377      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 378   char wrap_char;
 379
 380   /* Function callbacks.  */
 381   const struct bfd_link_callbacks *callbacks;
 382
 383   /* Hash table handled by BFD.  */
 384   struct bfd_link_hash_table *hash;
 385
 386   /* Hash table of symbols to keep.  This is NULL unless strip is
 387      strip_some.  */
 388   struct bfd_hash_table *keep_hash;
 389
 390   /* Hash table of symbols to report back via the notice callback.  If
 391      this is NULL, and notice_all is FALSE, then no symbols are
 392      reported back.  */
 393   struct bfd_hash_table *notice_hash;
 394
 395   /* Hash table of symbols which are being wrapped (the --wrap linker
 396      option).  If this is NULL, no symbols are being wrapped.  */
 397   struct bfd_hash_table *wrap_hash;
 398
 399   /* The list of input BFD's involved in the link.  These are chained
 400      together via the link_next field.  */
 401   bfd *input_bfds;
 402   bfd **input_bfds_tail;
 403
 404   /* If a symbol should be created for each input BFD, this is section
 405      where those symbols should be placed.  It must be a section in
 406      the output BFD.  It may be NULL, in which case no such symbols
 407      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 408      linker command language.  */
 409   asection *create_object_symbols_section;
 410
 411   /* List of global symbol names that are starting points for marking
 412      sections against garbage collection.  */
 413   struct bfd_sym_chain *gc_sym_list;
 414
 415   /* If a base output file is wanted, then this points to it */
 416   void *base_file;
 417
 418   /* The function to call when the executable or shared object is
 419      loaded.  */
 420   const char *init_function;
 421
 422   /* The function to call when the executable or shared object is
 423      unloaded.  */
 424   const char *fini_function;
 425
 426   /* Number of relaxation passes.  Usually only one relaxation pass
 427      is needed.  But a backend can have as many relaxation passes as
 428      necessary.  During bfd_relax_section call, it is set to the
 429      current pass, starting from 0.  */
 430   int relax_pass;
 431
 432   /* Number of relaxation trips.  This number is incremented every
 433      time the relaxation pass is restarted due to a previous
 434      relaxation returning true in *AGAIN.  */
 435   int relax_trip;
 436
 437   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 438      should be generated/linked against.  Set to 1 if this feature
 439      is explicitly requested by the user, -1 if enabled by default.  */
 440   int pei386_auto_import;
 441
 442   /* Non-zero if runtime relocs for DATA items with non-zero addends
 443      in pei386 DLLs should be generated.  Set to 1 if this feature
 444      is explicitly requested by the user, -1 if enabled by default.  */
 445   int pei386_runtime_pseudo_reloc;
 446
 447   /* How many spare .dynamic DT_NULL entries should be added?  */
 448   unsigned int spare_dynamic_tags;
 449
 450   /* May be used to set DT_FLAGS for ELF. */
 451   bfd_vma flags;
 452
 453   /* May be used to set DT_FLAGS_1 for ELF. */
 454   bfd_vma flags_1;
 455
 456   /* Start and end of RELRO region.  */
 457   bfd_vma relro_start, relro_end;
 458
 459   /* List of symbols should be dynamic.  */
 460   struct bfd_elf_dynamic_list *dynamic_list;
 461 };
 462
 463 /* This structures holds a set of callback functions.  These are called
 464    by the BFD linker routines.  Except for the info functions, the first
 465    argument to each callback function is the bfd_link_info structure
 466    being used and each function returns a boolean value.  If the
 467    function returns FALSE, then the BFD function which called it should
 468    return with a failure indication.  */
 469
 470 struct bfd_link_callbacks
 471 {
 472   /* A function which is called when an object is added from an
 473      archive.  ABFD is the archive element being added.  NAME is the
 474      name of the symbol which caused the archive element to be pulled
 475      in.  */
 476   bfd_boolean (*add_archive_element)
 477     (struct bfd_link_info *, bfd *abfd, const char *name);
 478   /* A function which is called when a symbol is found with multiple
 479      definitions.  NAME is the symbol which is defined multiple times.
 480      OBFD is the old BFD, OSEC is the old section, OVAL is the old
 481      value, NBFD is the new BFD, NSEC is the new section, and NVAL is
 482      the new value.  OBFD may be NULL.  OSEC and NSEC may be
 483      bfd_com_section or bfd_ind_section.  */
 484   bfd_boolean (*multiple_definition)
 485     (struct bfd_link_info *, const char *name,
 486      bfd *obfd, asection *osec, bfd_vma oval,
 487      bfd *nbfd, asection *nsec, bfd_vma nval);
 488   /* A function which is called when a common symbol is defined
 489      multiple times.  NAME is the symbol appearing multiple times.
 490      OBFD is the BFD of the existing symbol; it may be NULL if this is
 491      not known.  OTYPE is the type of the existing symbol, which may
 492      be bfd_link_hash_defined, bfd_link_hash_defweak,
 493      bfd_link_hash_common, or bfd_link_hash_indirect.  If OTYPE is
 494      bfd_link_hash_common, OSIZE is the size of the existing symbol.
 495      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 496      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 497      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 498      is the size of the new symbol.  */
 499   bfd_boolean (*multiple_common)
 500     (struct bfd_link_info *, const char *name,
 501      bfd *obfd, enum bfd_link_hash_type otype, bfd_vma osize,
 502      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 503   /* A function which is called to add a symbol to a set.  ENTRY is
 504      the link hash table entry for the set itself (e.g.,
 505      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 506      the set when generating a relocatable file, and is also used to
 507      get the size of the entry when generating an executable file.
 508      ABFD, SEC and VALUE identify the value to add to the set.  */
 509   bfd_boolean (*add_to_set)
 510     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 511      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 512   /* A function which is called when the name of a g++ constructor or
 513      destructor is found.  This is only called by some object file
 514      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 515      destructor.  This will use BFD_RELOC_CTOR when generating a
 516      relocatable file.  NAME is the name of the symbol found.  ABFD,
 517      SECTION and VALUE are the value of the symbol.  */
 518   bfd_boolean (*constructor)
 519     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 520      bfd *abfd, asection *sec, bfd_vma value);
 521   /* A function which is called to issue a linker warning.  For
 522      example, this is called when there is a reference to a warning
 523      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 524      of the symbol which triggered the warning; it may be NULL if
 525      there is none.  ABFD, SECTION and ADDRESS identify the location
 526      which trigerred the warning; either ABFD or SECTION or both may
 527      be NULL if the location is not known.  */
 528   bfd_boolean (*warning)
 529     (struct bfd_link_info *, const char *warning, const char *symbol,
 530      bfd *abfd, asection *section, bfd_vma address);
 531   /* A function which is called when a relocation is attempted against
 532      an undefined symbol.  NAME is the symbol which is undefined.
 533      ABFD, SECTION and ADDRESS identify the location from which the
 534      reference is made. FATAL indicates whether an undefined symbol is
 535      a fatal error or not. In some cases SECTION may be NULL.  */
 536   bfd_boolean (*undefined_symbol)
 537     (struct bfd_link_info *, const char *name, bfd *abfd,
 538      asection *section, bfd_vma address, bfd_boolean fatal);
 539   /* A function which is called when a reloc overflow occurs. ENTRY is
 540      the link hash table entry for the symbol the reloc is against.
 541      NAME is the name of the local symbol or section the reloc is
 542      against, RELOC_NAME is the name of the relocation, and ADDEND is
 543      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 544      location at which the overflow occurs; if this is the result of a
 545      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 546      ABFD will be NULL.  */
 547   bfd_boolean (*reloc_overflow)
 548     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 549      const char *name, const char *reloc_name, bfd_vma addend,
 550      bfd *abfd, asection *section, bfd_vma address);
 551   /* A function which is called when a dangerous reloc is performed.
 552      MESSAGE is an appropriate message.
 553      ABFD, SECTION and ADDRESS identify the location at which the
 554      problem occurred; if this is the result of a
 555      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 556      ABFD will be NULL.  */
 557   bfd_boolean (*reloc_dangerous)
 558     (struct bfd_link_info *, const char *message,
 559      bfd *abfd, asection *section, bfd_vma address);
 560   /* A function which is called when a reloc is found to be attached
 561      to a symbol which is not being written out.  NAME is the name of
 562      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 563      the reloc; 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 (*unattached_reloc)
 567     (struct bfd_link_info *, const char *name,
 568      bfd *abfd, asection *section, bfd_vma address);
 569   /* A function which is called when a symbol in notice_hash is
 570      defined or referenced.  NAME is the symbol.  ABFD, SECTION and
 571      ADDRESS are the value of the symbol.  If SECTION is
 572      bfd_und_section, this is a reference.  */
 573   bfd_boolean (*notice)
 574     (struct bfd_link_info *, const char *name,
 575      bfd *abfd, asection *section, bfd_vma address);
 576   /* Error or warning link info message.  */
 577   void (*einfo)
 578     (const char *fmt, ...);
 579   /* General link info message.  */
 580   void (*info)
 581     (const char *fmt, ...);
 582   /* Message to be printed in linker map file.  */
 583   void (*minfo)
 584     (const char *fmt, ...);
 585   /* This callback provides a chance for users of the BFD library to
 586      override its decision about whether to place two adjacent sections
 587      into the same segment.  */
 588   bfd_boolean (*override_segment_assignment)
 589     (struct bfd_link_info *, bfd * abfd,
 590      asection * current_section, asection * previous_section,
 591      bfd_boolean new_segment);
 592 };
 593 \f
 594 /* The linker builds link_order structures which tell the code how to
 595    include input data in the output file.  */
 596
 597 /* These are the types of link_order structures.  */
 598
 599 enum bfd_link_order_type
 600 {
 601   bfd_undefined_link_order,     /* Undefined.  */
 602   bfd_indirect_link_order,      /* Built from a section.  */
 603   bfd_data_link_order,          /* Set to explicit data.  */
 604   bfd_section_reloc_link_order, /* Relocate against a section.  */
 605   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 606 };
 607
 608 /* This is the link_order structure itself.  These form a chain
 609    attached to the output section whose contents they are describing.  */
 610
 611 struct bfd_link_order
 612 {
 613   /* Next link_order in chain.  */
 614   struct bfd_link_order *next;
 615   /* Type of link_order.  */
 616   enum bfd_link_order_type type;
 617   /* Offset within output section.  */
 618   bfd_vma offset;
 619   /* Size within output section.  */
 620   bfd_size_type size;
 621   /* Type specific information.  */
 622   union
 623     {
 624       struct
 625         {
 626           /* Section to include.  If this is used, then
 627              section->output_section must be the section the
 628              link_order is attached to, section->output_offset must
 629              equal the link_order offset field, and section->size
 630              must equal the link_order size field.  Maybe these
 631              restrictions should be relaxed someday.  */
 632           asection *section;
 633         } indirect;
 634       struct
 635         {
 636           /* Size of contents, or zero when contents size == size
 637              within output section.
 638              A non-zero value allows filling of the output section
 639              with an arbitrary repeated pattern.  */
 640           unsigned int size;
 641           /* Data to put into file.  */
 642           bfd_byte *contents;
 643         } data;
 644       struct
 645         {
 646           /* Description of reloc to generate.  Used for
 647              bfd_section_reloc_link_order and
 648              bfd_symbol_reloc_link_order.  */
 649           struct bfd_link_order_reloc *p;
 650         } reloc;
 651     } u;
 652 };
 653
 654 /* A linker order of type bfd_section_reloc_link_order or
 655    bfd_symbol_reloc_link_order means to create a reloc against a
 656    section or symbol, respectively.  This is used to implement -Ur to
 657    generate relocs for the constructor tables.  The
 658    bfd_link_order_reloc structure describes the reloc that BFD should
 659    create.  It is similar to a arelent, but I didn't use arelent
 660    because the linker does not know anything about most symbols, and
 661    any asymbol structure it creates will be partially meaningless.
 662    This information could logically be in the bfd_link_order struct,
 663    but I didn't want to waste the space since these types of relocs
 664    are relatively rare.  */
 665
 666 struct bfd_link_order_reloc
 667 {
 668   /* Reloc type.  */
 669   bfd_reloc_code_real_type reloc;
 670
 671   union
 672     {
 673       /* For type bfd_section_reloc_link_order, this is the section
 674          the reloc should be against.  This must be a section in the
 675          output BFD, not any of the input BFDs.  */
 676       asection *section;
 677       /* For type bfd_symbol_reloc_link_order, this is the name of the
 678          symbol the reloc should be against.  */
 679       const char *name;
 680     } u;
 681
 682   /* Addend to use.  The object file should contain zero.  The BFD
 683      backend is responsible for filling in the contents of the object
 684      file correctly.  For some object file formats (e.g., COFF) the
 685      addend must be stored into in the object file, and for some
 686      (e.g., SPARC a.out) it is kept in the reloc.  */
 687   bfd_vma addend;
 688 };
 689
 690 /* Allocate a new link_order for a section.  */
 691 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 692
 693 /* These structures are used to describe version information for the
 694    ELF linker.  These structures could be manipulated entirely inside
 695    BFD, but it would be a pain.  Instead, the regular linker sets up
 696    these structures, and then passes them into BFD.  */
 697
 698 /* Glob pattern for a version.  */
 699
 700 struct bfd_elf_version_expr
 701 {
 702   /* Next glob pattern for this version.  */
 703   struct bfd_elf_version_expr *next;
 704   /* Glob pattern.  */
 705   const char *pattern;
 706   /* NULL for a glob pattern, otherwise a straight symbol.  */
 707   const char *symbol;
 708   /* Defined by ".symver".  */
 709   unsigned int symver : 1;
 710   /* Defined by version script.  */
 711   unsigned int script : 1;
 712   /* Pattern type.  */
 713 #define BFD_ELF_VERSION_C_TYPE          1
 714 #define BFD_ELF_VERSION_CXX_TYPE        2
 715 #define BFD_ELF_VERSION_JAVA_TYPE       4
 716   unsigned int mask : 3;
 717 };
 718
 719 struct bfd_elf_version_expr_head
 720 {
 721   /* List of all patterns, both wildcards and non-wildcards.  */
 722   struct bfd_elf_version_expr *list;
 723   /* Hash table for non-wildcards.  */
 724   void *htab;
 725   /* Remaining patterns.  */
 726   struct bfd_elf_version_expr *remaining;
 727   /* What kind of pattern types are present in list (bitmask).  */
 728   unsigned int mask;
 729 };
 730
 731 /* Version dependencies.  */
 732
 733 struct bfd_elf_version_deps
 734 {
 735   /* Next dependency for this version.  */
 736   struct bfd_elf_version_deps *next;
 737   /* The version which this version depends upon.  */
 738   struct bfd_elf_version_tree *version_needed;
 739 };
 740
 741 /* A node in the version tree.  */
 742
 743 struct bfd_elf_version_tree
 744 {
 745   /* Next version.  */
 746   struct bfd_elf_version_tree *next;
 747   /* Name of this version.  */
 748   const char *name;
 749   /* Version number.  */
 750   unsigned int vernum;
 751   /* Regular expressions for global symbols in this version.  */
 752   struct bfd_elf_version_expr_head globals;
 753   /* Regular expressions for local symbols in this version.  */
 754   struct bfd_elf_version_expr_head locals;
 755   /* List of versions which this version depends upon.  */
 756   struct bfd_elf_version_deps *deps;
 757   /* Index of the version name.  This is used within BFD.  */
 758   unsigned int name_indx;
 759   /* Whether this version tree was used.  This is used within BFD.  */
 760   int used;
 761   /* Matching hook.  */
 762   struct bfd_elf_version_expr *(*match)
 763     (struct bfd_elf_version_expr_head *head,
 764      struct bfd_elf_version_expr *prev, const char *sym);
 765 };
 766
 767 struct bfd_elf_dynamic_list
 768 {
 769   struct bfd_elf_version_expr_head head;
 770   struct bfd_elf_version_expr *(*match)
 771     (struct bfd_elf_version_expr_head *head,
 772      struct bfd_elf_version_expr *prev, const char *sym);
 773 };
 774
 775 #endif