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