include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
   3    2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
   4    Free Software Foundation, Inc.
   5    Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
   6
   7    This file is part of BFD, the Binary File Descriptor library.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  22    MA 02110-1301, USA.  */
  23
  24 #ifndef BFDLINK_H
  25 #define BFDLINK_H
  26
  27 /* Which symbols to strip during a link.  */
  28 enum bfd_link_strip
  29 {
  30   strip_none,           /* Don't strip any symbols.  */
  31   strip_debugger,       /* Strip debugging symbols.  */
  32   strip_some,           /* keep_hash is the list of symbols to keep.  */
  33   strip_all             /* Strip all symbols.  */
  34 };
  35
  36 /* Which local symbols to discard during a link.  This is irrelevant
  37    if strip_all is used.  */
  38 enum bfd_link_discard
  39 {
  40   discard_sec_merge,    /* Discard local temporary symbols in SEC_MERGE
  41                            sections.  */
  42   discard_none,         /* Don't discard any locals.  */
  43   discard_l,            /* Discard local temporary symbols.  */
  44   discard_all           /* Discard all locals.  */
  45 };
  46
  47 /* Describes the type of hash table entry structure being used.
  48    Different hash table structure have different fields and so
  49    support different linking features.  */
  50 enum bfd_link_hash_table_type
  51   {
  52     bfd_link_generic_hash_table,
  53     bfd_link_elf_hash_table
  54   };
  55 \f
  56 /* These are the possible types of an entry in the BFD link hash
  57    table.  */
  58
  59 enum bfd_link_hash_type
  60 {
  61   bfd_link_hash_new,            /* Symbol is new.  */
  62   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  63   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  64   bfd_link_hash_defined,        /* Symbol is defined.  */
  65   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  66   bfd_link_hash_common,         /* Symbol is common.  */
  67   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  68   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  69 };
  70
  71 enum bfd_link_common_skip_ar_symbols
  72 {
  73   bfd_link_common_skip_none,
  74   bfd_link_common_skip_text,
  75   bfd_link_common_skip_data,
  76   bfd_link_common_skip_all
  77 };
  78
  79 struct bfd_link_hash_common_entry
  80   {
  81     unsigned int alignment_power;       /* Alignment.  */
  82     asection *section;          /* Symbol section.  */
  83   };
  84
  85 /* The linking routines use a hash table which uses this structure for
  86    its elements.  */
  87
  88 struct bfd_link_hash_entry
  89 {
  90   /* Base hash table entry structure.  */
  91   struct bfd_hash_entry root;
  92
  93   /* Type of this entry.  */
  94   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
  95
  96   unsigned int non_ir_ref : 1;
  97
  98   /* A union of information depending upon the type.  */
  99   union
 100     {
 101       /* Nothing is kept for bfd_hash_new.  */
 102       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 103       struct
 104         {
 105           /* Undefined and common symbols are kept in a linked list through
 106              this field.  This field is present in all of the union element
 107              so that we don't need to remove entries from the list when we
 108              change their type.  Removing entries would either require the
 109              list to be doubly linked, which would waste more memory, or
 110              require a traversal.  When an undefined or common symbol is
 111              created, it should be added to this list, the head of which is in
 112              the link hash table itself.  As symbols are defined, they need
 113              not be removed from the list; anything which reads the list must
 114              doublecheck the symbol type.
 115
 116              Weak symbols are not kept on this list.
 117
 118              Defined and defweak symbols use this field as a reference marker.
 119              If the field is not NULL, or this structure is the tail of the
 120              undefined symbol list, the symbol has been referenced.  If the
 121              symbol is undefined and becomes defined, this field will
 122              automatically be non-NULL since the symbol will have been on the
 123              undefined symbol list.  */
 124           struct bfd_link_hash_entry *next;
 125           bfd *abfd;            /* BFD symbol was found in.  */
 126         } undef;
 127       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 128       struct
 129         {
 130           struct bfd_link_hash_entry *next;
 131           asection *section;    /* Symbol section.  */
 132           bfd_vma value;        /* Symbol value.  */
 133         } def;
 134       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 135       struct
 136         {
 137           struct bfd_link_hash_entry *next;
 138           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 139           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 140         } i;
 141       /* bfd_link_hash_common.  */
 142       struct
 143         {
 144           struct bfd_link_hash_entry *next;
 145           /* The linker needs to know three things about common
 146              symbols: the size, the alignment, and the section in
 147              which the symbol should be placed.  We store the size
 148              here, and we allocate a small structure to hold the
 149              section and the alignment.  The alignment is stored as a
 150              power of two.  We don't store all the information
 151              directly because we don't want to increase the size of
 152              the union; this structure is a major space user in the
 153              linker.  */
 154           struct bfd_link_hash_common_entry *p;
 155           bfd_size_type size;   /* Common symbol size.  */
 156         } c;
 157     } u;
 158 };
 159
 160 /* This is the link hash table.  It is a derived class of
 161    bfd_hash_table.  */
 162
 163 struct bfd_link_hash_table
 164 {
 165   /* The hash table itself.  */
 166   struct bfd_hash_table table;
 167   /* A linked list of undefined and common symbols, linked through the
 168      next field in the bfd_link_hash_entry structure.  */
 169   struct bfd_link_hash_entry *undefs;
 170   /* Entries are added to the tail of the undefs list.  */
 171   struct bfd_link_hash_entry *undefs_tail;
 172   /* The type of the link hash table.  */
 173   enum bfd_link_hash_table_type type;
 174 };
 175
 176 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 177    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 178    the real symbol.  */
 179 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 180   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 181    bfd_boolean copy, bfd_boolean follow);
 182
 183 /* Look up an entry in the main linker hash table if the symbol might
 184    be wrapped.  This should only be used for references to an
 185    undefined symbol, not for definitions of a symbol.  */
 186
 187 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 188   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 189    bfd_boolean, bfd_boolean);
 190
 191 /* Traverse a link hash table.  */
 192 extern void bfd_link_hash_traverse
 193   (struct bfd_link_hash_table *,
 194     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 195     void *);
 196
 197 /* Add an entry to the undefs list.  */
 198 extern void bfd_link_add_undef
 199   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 200
 201 /* Remove symbols from the undefs list that don't belong there.  */
 202 extern void bfd_link_repair_undef_list
 203   (struct bfd_link_hash_table *table);
 204
 205 /* Read symbols and cache symbol pointer array in outsymbols.  */
 206 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 207
 208 struct bfd_sym_chain
 209 {
 210   struct bfd_sym_chain *next;
 211   const char *name;
 212 };
 213 \f
 214 /* How to handle unresolved symbols.
 215    There are four possibilities which are enumerated below:  */
 216 enum report_method
 217 {
 218   /* This is the initial value when then link_info structure is created.
 219      It allows the various stages of the linker to determine whether they
 220      allowed to set the value.  */
 221   RM_NOT_YET_SET = 0,
 222   RM_IGNORE,
 223   RM_GENERATE_WARNING,
 224   RM_GENERATE_ERROR
 225 };
 226
 227 typedef enum {with_flags, without_flags} flag_type;
 228
 229 /* A section flag list.  */
 230 struct flag_info_list
 231 {
 232   flag_type with;
 233   const char *name;
 234   bfd_boolean valid;
 235   struct flag_info_list *next;
 236 };
 237
 238 /* Section flag info.  */
 239 struct flag_info
 240 {
 241   flagword only_with_flags;
 242   flagword not_with_flags;
 243   struct flag_info_list *flag_list;
 244   bfd_boolean flags_initialized;
 245 };
 246
 247 struct bfd_elf_dynamic_list;
 248
 249 /* This structure holds all the information needed to communicate
 250    between BFD and the linker when doing a link.  */
 251
 252 struct bfd_link_info
 253 {
 254   /* TRUE if BFD should generate a relocatable object file.  */
 255   unsigned int relocatable: 1;
 256
 257   /* TRUE if BFD should generate relocation information in the final
 258      executable.  */
 259   unsigned int emitrelocations: 1;
 260
 261   /* TRUE if BFD should generate a "task linked" object file,
 262      similar to relocatable but also with globals converted to
 263      statics.  */
 264   unsigned int task_link: 1;
 265
 266   /* TRUE if BFD should generate a shared object.  */
 267   unsigned int shared: 1;
 268
 269   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 270   unsigned int symbolic: 1;
 271
 272   /* TRUE if BFD should export all symbols in the dynamic symbol table
 273      of an executable, rather than only those used.  */
 274   unsigned int export_dynamic: 1;
 275
 276   /* TRUE if shared objects should be linked directly, not shared.  */
 277   unsigned int static_link: 1;
 278
 279   /* TRUE if the output file should be in a traditional format.  This
 280      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 281      on the output file, but may be checked when reading the input
 282      files.  */
 283   unsigned int traditional_format: 1;
 284
 285   /* TRUE if we want to produced optimized output files.  This might
 286      need much more time and therefore must be explicitly selected.  */
 287   unsigned int optimize: 1;
 288
 289   /* TRUE if ok to have multiple definition.  */
 290   unsigned int allow_multiple_definition: 1;
 291
 292   /* TRUE if ok to have version with no definition.  */
 293   unsigned int allow_undefined_version: 1;
 294
 295   /* TRUE if a default symbol version should be created and used for
 296      exported symbols.  */
 297   unsigned int create_default_symver: 1;
 298
 299   /* TRUE if a default symbol version should be created and used for
 300      imported symbols.  */
 301   unsigned int default_imported_symver: 1;
 302
 303   /* TRUE if symbols should be retained in memory, FALSE if they
 304      should be freed and reread.  */
 305   unsigned int keep_memory: 1;
 306
 307   /* TRUE if every symbol should be reported back via the notice
 308      callback.  */
 309   unsigned int notice_all: 1;
 310
 311   /* TRUE if executable should not contain copy relocs.
 312      Setting this true may result in a non-sharable text segment.  */
 313   unsigned int nocopyreloc: 1;
 314
 315   /* TRUE if the new ELF dynamic tags are enabled. */
 316   unsigned int new_dtags: 1;
 317
 318   /* TRUE if non-PLT relocs should be merged into one reloc section
 319      and sorted so that relocs against the same symbol come together.  */
 320   unsigned int combreloc: 1;
 321
 322   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 323      should be created.  */
 324   unsigned int eh_frame_hdr: 1;
 325
 326   /* TRUE if global symbols in discarded sections should be stripped.  */
 327   unsigned int strip_discarded: 1;
 328
 329   /* TRUE if generating a position independent executable.  */
 330   unsigned int pie: 1;
 331
 332   /* TRUE if generating an executable, position independent or not.  */
 333   unsigned int executable : 1;
 334
 335   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 336      flags.  */
 337   unsigned int execstack: 1;
 338
 339   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 340      flags.  */
 341   unsigned int noexecstack: 1;
 342
 343   /* TRUE if PT_GNU_RELRO segment should be created.  */
 344   unsigned int relro: 1;
 345
 346   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 347   unsigned int warn_shared_textrel: 1;
 348
 349   /* TRUE if we should warn alternate ELF machine code.  */
 350   unsigned int warn_alternate_em: 1;
 351
 352   /* TRUE if unreferenced sections should be removed.  */
 353   unsigned int gc_sections: 1;
 354
 355   /* TRUE if user shoudl be informed of removed unreferenced sections.  */
 356   unsigned int print_gc_sections: 1;
 357
 358   /* TRUE if .hash section should be created.  */
 359   unsigned int emit_hash: 1;
 360
 361   /* TRUE if .gnu.hash section should be created.  */
 362   unsigned int emit_gnu_hash: 1;
 363
 364   /* If TRUE reduce memory overheads, at the expense of speed. This will
 365      cause map file generation to use an O(N^2) algorithm and disable
 366      caching ELF symbol buffer.  */
 367   unsigned int reduce_memory_overheads: 1;
 368
 369   /* TRUE if all data symbols should be dynamic.  */
 370    unsigned int dynamic_data: 1;
 371
 372   /* TRUE if some symbols have to be dynamic, controlled by
 373      --dynamic-list command line options.  */
 374   unsigned int dynamic: 1;
 375
 376   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 377      linker created sections, TRUE if it should be omitted.  */
 378   unsigned int no_ld_generated_unwind_info: 1;
 379
 380   /* TRUE if we are loading LTO outputs.  */
 381   unsigned int loading_lto_outputs: 1;
 382
 383   /* Non-NULL if .note.gnu.build-id section should be created.  */
 384   char *emit_note_gnu_build_id;
 385
 386   /* What to do with unresolved symbols in an object file.
 387      When producing executables the default is GENERATE_ERROR.
 388      When producing shared libraries the default is IGNORE.  The
 389      assumption with shared libraries is that the reference will be
 390      resolved at load/execution time.  */
 391   enum report_method unresolved_syms_in_objects;
 392
 393   /* What to do with unresolved symbols in a shared library.
 394      The same defaults apply.  */
 395   enum report_method unresolved_syms_in_shared_libs;
 396
 397   /* Which symbols to strip.  */
 398   enum bfd_link_strip strip;
 399
 400   /* Which local symbols to discard.  */
 401   enum bfd_link_discard discard;
 402
 403   /* Criteria for skipping symbols when determining
 404      whether to include an object from an archive. */
 405   enum bfd_link_common_skip_ar_symbols common_skip_ar_symbols;
 406
 407   /* Char that may appear as the first char of a symbol, but should be
 408      skipped (like symbol_leading_char) when looking up symbols in
 409      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 410   char wrap_char;
 411
 412   /* Separator between archive and filename in linker script filespecs.  */
 413   char path_separator;
 414
 415   /* Function callbacks.  */
 416   const struct bfd_link_callbacks *callbacks;
 417
 418   /* Hash table handled by BFD.  */
 419   struct bfd_link_hash_table *hash;
 420
 421   /* Hash table of symbols to keep.  This is NULL unless strip is
 422      strip_some.  */
 423   struct bfd_hash_table *keep_hash;
 424
 425   /* Hash table of symbols to report back via the notice callback.  If
 426      this is NULL, and notice_all is FALSE, then no symbols are
 427      reported back.  */
 428   struct bfd_hash_table *notice_hash;
 429
 430   /* Hash table of symbols which are being wrapped (the --wrap linker
 431      option).  If this is NULL, no symbols are being wrapped.  */
 432   struct bfd_hash_table *wrap_hash;
 433
 434   /* The output BFD.  */
 435   bfd *output_bfd;
 436
 437   /* The list of input BFD's involved in the link.  These are chained
 438      together via the link_next field.  */
 439   bfd *input_bfds;
 440   bfd **input_bfds_tail;
 441
 442   /* If a symbol should be created for each input BFD, this is section
 443      where those symbols should be placed.  It must be a section in
 444      the output BFD.  It may be NULL, in which case no such symbols
 445      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 446      linker command language.  */
 447   asection *create_object_symbols_section;
 448
 449   /* List of global symbol names that are starting points for marking
 450      sections against garbage collection.  */
 451   struct bfd_sym_chain *gc_sym_list;
 452
 453   /* If a base output file is wanted, then this points to it */
 454   void *base_file;
 455
 456   /* The function to call when the executable or shared object is
 457      loaded.  */
 458   const char *init_function;
 459
 460   /* The function to call when the executable or shared object is
 461      unloaded.  */
 462   const char *fini_function;
 463
 464   /* Number of relaxation passes.  Usually only one relaxation pass
 465      is needed.  But a backend can have as many relaxation passes as
 466      necessary.  During bfd_relax_section call, it is set to the
 467      current pass, starting from 0.  */
 468   int relax_pass;
 469
 470   /* Number of relaxation trips.  This number is incremented every
 471      time the relaxation pass is restarted due to a previous
 472      relaxation returning true in *AGAIN.  */
 473   int relax_trip;
 474
 475   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 476      should be generated/linked against.  Set to 1 if this feature
 477      is explicitly requested by the user, -1 if enabled by default.  */
 478   int pei386_auto_import;
 479
 480   /* Non-zero if runtime relocs for DATA items with non-zero addends
 481      in pei386 DLLs should be generated.  Set to 1 if this feature
 482      is explicitly requested by the user, -1 if enabled by default.  */
 483   int pei386_runtime_pseudo_reloc;
 484
 485   /* How many spare .dynamic DT_NULL entries should be added?  */
 486   unsigned int spare_dynamic_tags;
 487
 488   /* May be used to set DT_FLAGS for ELF. */
 489   bfd_vma flags;
 490
 491   /* May be used to set DT_FLAGS_1 for ELF. */
 492   bfd_vma flags_1;
 493
 494   /* Start and end of RELRO region.  */
 495   bfd_vma relro_start, relro_end;
 496
 497   /* List of symbols should be dynamic.  */
 498   struct bfd_elf_dynamic_list *dynamic_list;
 499 };
 500
 501 /* This structures holds a set of callback functions.  These are called
 502    by the BFD linker routines.  Except for the info functions, the first
 503    argument to each callback function is the bfd_link_info structure
 504    being used and each function returns a boolean value.  If the
 505    function returns FALSE, then the BFD function which called it should
 506    return with a failure indication.  */
 507
 508 struct bfd_link_callbacks
 509 {
 510   /* A function which is called when an object is added from an
 511      archive.  ABFD is the archive element being added.  NAME is the
 512      name of the symbol which caused the archive element to be pulled
 513      in.  This function may set *SUBSBFD to point to an alternative
 514      BFD from which symbols should in fact be added in place of the
 515      original BFD's symbols.  */
 516   bfd_boolean (*add_archive_element)
 517     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 518   /* A function which is called when a symbol is found with multiple
 519      definitions.  H is the symbol which is defined multiple times.
 520      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 521      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 522   bfd_boolean (*multiple_definition)
 523     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 524      bfd *nbfd, asection *nsec, bfd_vma nval);
 525   /* A function which is called when a common symbol is defined
 526      multiple times.  H is the symbol appearing multiple times.
 527      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 528      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 529      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 530      is the size of the new symbol.  */
 531   bfd_boolean (*multiple_common)
 532     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 533      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 534   /* A function which is called to add a symbol to a set.  ENTRY is
 535      the link hash table entry for the set itself (e.g.,
 536      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 537      the set when generating a relocatable file, and is also used to
 538      get the size of the entry when generating an executable file.
 539      ABFD, SEC and VALUE identify the value to add to the set.  */
 540   bfd_boolean (*add_to_set)
 541     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 542      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 543   /* A function which is called when the name of a g++ constructor or
 544      destructor is found.  This is only called by some object file
 545      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 546      destructor.  This will use BFD_RELOC_CTOR when generating a
 547      relocatable file.  NAME is the name of the symbol found.  ABFD,
 548      SECTION and VALUE are the value of the symbol.  */
 549   bfd_boolean (*constructor)
 550     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 551      bfd *abfd, asection *sec, bfd_vma value);
 552   /* A function which is called to issue a linker warning.  For
 553      example, this is called when there is a reference to a warning
 554      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 555      of the symbol which triggered the warning; it may be NULL if
 556      there is none.  ABFD, SECTION and ADDRESS identify the location
 557      which trigerred the warning; either ABFD or SECTION or both may
 558      be NULL if the location is not known.  */
 559   bfd_boolean (*warning)
 560     (struct bfd_link_info *, const char *warning, const char *symbol,
 561      bfd *abfd, asection *section, bfd_vma address);
 562   /* A function which is called when a relocation is attempted against
 563      an undefined symbol.  NAME is the symbol which is undefined.
 564      ABFD, SECTION and ADDRESS identify the location from which the
 565      reference is made. IS_FATAL indicates whether an undefined symbol is
 566      a fatal error or not. In some cases SECTION may be NULL.  */
 567   bfd_boolean (*undefined_symbol)
 568     (struct bfd_link_info *, const char *name, bfd *abfd,
 569      asection *section, bfd_vma address, bfd_boolean is_fatal);
 570   /* A function which is called when a reloc overflow occurs. ENTRY is
 571      the link hash table entry for the symbol the reloc is against.
 572      NAME is the name of the local symbol or section the reloc is
 573      against, RELOC_NAME is the name of the relocation, and ADDEND is
 574      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 575      location at which the overflow occurs; if this is the result of a
 576      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 577      ABFD will be NULL.  */
 578   bfd_boolean (*reloc_overflow)
 579     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 580      const char *name, const char *reloc_name, bfd_vma addend,
 581      bfd *abfd, asection *section, bfd_vma address);
 582   /* A function which is called when a dangerous reloc is performed.
 583      MESSAGE is an appropriate message.
 584      ABFD, SECTION and ADDRESS identify the location at which the
 585      problem occurred; if this is the result of a
 586      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 587      ABFD will be NULL.  */
 588   bfd_boolean (*reloc_dangerous)
 589     (struct bfd_link_info *, const char *message,
 590      bfd *abfd, asection *section, bfd_vma address);
 591   /* A function which is called when a reloc is found to be attached
 592      to a symbol which is not being written out.  NAME is the name of
 593      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 594      the reloc; if this is the result of a
 595      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 596      ABFD will be NULL.  */
 597   bfd_boolean (*unattached_reloc)
 598     (struct bfd_link_info *, const char *name,
 599      bfd *abfd, asection *section, bfd_vma address);
 600   /* A function which is called when a symbol in notice_hash is
 601      defined or referenced.  H is the symbol.  ABFD, SECTION and
 602      ADDRESS are the (new) value of the symbol.  If SECTION is
 603      bfd_und_section, this is a reference.  FLAGS are the symbol
 604      BSF_* flags.  STRING is the name of the symbol to indirect to if
 605      the sym is indirect, or the warning string if a warning sym.  */
 606   bfd_boolean (*notice)
 607     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 608      bfd *abfd, asection *section, bfd_vma address, flagword flags,
 609      const char *string);
 610   /* Error or warning link info message.  */
 611   void (*einfo)
 612     (const char *fmt, ...);
 613   /* General link info message.  */
 614   void (*info)
 615     (const char *fmt, ...);
 616   /* Message to be printed in linker map file.  */
 617   void (*minfo)
 618     (const char *fmt, ...);
 619   /* This callback provides a chance for users of the BFD library to
 620      override its decision about whether to place two adjacent sections
 621      into the same segment.  */
 622   bfd_boolean (*override_segment_assignment)
 623     (struct bfd_link_info *, bfd * abfd,
 624      asection * current_section, asection * previous_section,
 625      bfd_boolean new_segment);
 626 };
 627 \f
 628 /* The linker builds link_order structures which tell the code how to
 629    include input data in the output file.  */
 630
 631 /* These are the types of link_order structures.  */
 632
 633 enum bfd_link_order_type
 634 {
 635   bfd_undefined_link_order,     /* Undefined.  */
 636   bfd_indirect_link_order,      /* Built from a section.  */
 637   bfd_data_link_order,          /* Set to explicit data.  */
 638   bfd_section_reloc_link_order, /* Relocate against a section.  */
 639   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 640 };
 641
 642 /* This is the link_order structure itself.  These form a chain
 643    attached to the output section whose contents they are describing.  */
 644
 645 struct bfd_link_order
 646 {
 647   /* Next link_order in chain.  */
 648   struct bfd_link_order *next;
 649   /* Type of link_order.  */
 650   enum bfd_link_order_type type;
 651   /* Offset within output section.  */
 652   bfd_vma offset;
 653   /* Size within output section.  */
 654   bfd_size_type size;
 655   /* Type specific information.  */
 656   union
 657     {
 658       struct
 659         {
 660           /* Section to include.  If this is used, then
 661              section->output_section must be the section the
 662              link_order is attached to, section->output_offset must
 663              equal the link_order offset field, and section->size
 664              must equal the link_order size field.  Maybe these
 665              restrictions should be relaxed someday.  */
 666           asection *section;
 667         } indirect;
 668       struct
 669         {
 670           /* Size of contents, or zero when contents size == size
 671              within output section.
 672              A non-zero value allows filling of the output section
 673              with an arbitrary repeated pattern.  */
 674           unsigned int size;
 675           /* Data to put into file.  */
 676           bfd_byte *contents;
 677         } data;
 678       struct
 679         {
 680           /* Description of reloc to generate.  Used for
 681              bfd_section_reloc_link_order and
 682              bfd_symbol_reloc_link_order.  */
 683           struct bfd_link_order_reloc *p;
 684         } reloc;
 685     } u;
 686 };
 687
 688 /* A linker order of type bfd_section_reloc_link_order or
 689    bfd_symbol_reloc_link_order means to create a reloc against a
 690    section or symbol, respectively.  This is used to implement -Ur to
 691    generate relocs for the constructor tables.  The
 692    bfd_link_order_reloc structure describes the reloc that BFD should
 693    create.  It is similar to a arelent, but I didn't use arelent
 694    because the linker does not know anything about most symbols, and
 695    any asymbol structure it creates will be partially meaningless.
 696    This information could logically be in the bfd_link_order struct,
 697    but I didn't want to waste the space since these types of relocs
 698    are relatively rare.  */
 699
 700 struct bfd_link_order_reloc
 701 {
 702   /* Reloc type.  */
 703   bfd_reloc_code_real_type reloc;
 704
 705   union
 706     {
 707       /* For type bfd_section_reloc_link_order, this is the section
 708          the reloc should be against.  This must be a section in the
 709          output BFD, not any of the input BFDs.  */
 710       asection *section;
 711       /* For type bfd_symbol_reloc_link_order, this is the name of the
 712          symbol the reloc should be against.  */
 713       const char *name;
 714     } u;
 715
 716   /* Addend to use.  The object file should contain zero.  The BFD
 717      backend is responsible for filling in the contents of the object
 718      file correctly.  For some object file formats (e.g., COFF) the
 719      addend must be stored into in the object file, and for some
 720      (e.g., SPARC a.out) it is kept in the reloc.  */
 721   bfd_vma addend;
 722 };
 723
 724 /* Allocate a new link_order for a section.  */
 725 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 726
 727 /* These structures are used to describe version information for the
 728    ELF linker.  These structures could be manipulated entirely inside
 729    BFD, but it would be a pain.  Instead, the regular linker sets up
 730    these structures, and then passes them into BFD.  */
 731
 732 /* Glob pattern for a version.  */
 733
 734 struct bfd_elf_version_expr
 735 {
 736   /* Next glob pattern for this version.  */
 737   struct bfd_elf_version_expr *next;
 738   /* Glob pattern.  */
 739   const char *pattern;
 740   /* Set if pattern is not a glob.  */
 741   unsigned int literal : 1;
 742   /* Defined by ".symver".  */
 743   unsigned int symver : 1;
 744   /* Defined by version script.  */
 745   unsigned int script : 1;
 746   /* Pattern type.  */
 747 #define BFD_ELF_VERSION_C_TYPE          1
 748 #define BFD_ELF_VERSION_CXX_TYPE        2
 749 #define BFD_ELF_VERSION_JAVA_TYPE       4
 750   unsigned int mask : 3;
 751 };
 752
 753 struct bfd_elf_version_expr_head
 754 {
 755   /* List of all patterns, both wildcards and non-wildcards.  */
 756   struct bfd_elf_version_expr *list;
 757   /* Hash table for non-wildcards.  */
 758   void *htab;
 759   /* Remaining patterns.  */
 760   struct bfd_elf_version_expr *remaining;
 761   /* What kind of pattern types are present in list (bitmask).  */
 762   unsigned int mask;
 763 };
 764
 765 /* Version dependencies.  */
 766
 767 struct bfd_elf_version_deps
 768 {
 769   /* Next dependency for this version.  */
 770   struct bfd_elf_version_deps *next;
 771   /* The version which this version depends upon.  */
 772   struct bfd_elf_version_tree *version_needed;
 773 };
 774
 775 /* A node in the version tree.  */
 776
 777 struct bfd_elf_version_tree
 778 {
 779   /* Next version.  */
 780   struct bfd_elf_version_tree *next;
 781   /* Name of this version.  */
 782   const char *name;
 783   /* Version number.  */
 784   unsigned int vernum;
 785   /* Regular expressions for global symbols in this version.  */
 786   struct bfd_elf_version_expr_head globals;
 787   /* Regular expressions for local symbols in this version.  */
 788   struct bfd_elf_version_expr_head locals;
 789   /* List of versions which this version depends upon.  */
 790   struct bfd_elf_version_deps *deps;
 791   /* Index of the version name.  This is used within BFD.  */
 792   unsigned int name_indx;
 793   /* Whether this version tree was used.  This is used within BFD.  */
 794   int used;
 795   /* Matching hook.  */
 796   struct bfd_elf_version_expr *(*match)
 797     (struct bfd_elf_version_expr_head *head,
 798      struct bfd_elf_version_expr *prev, const char *sym);
 799 };
 800
 801 struct bfd_elf_dynamic_list
 802 {
 803   struct bfd_elf_version_expr_head head;
 804   struct bfd_elf_version_expr *(*match)
 805     (struct bfd_elf_version_expr_head *head,
 806      struct bfd_elf_version_expr *prev, const char *sym);
 807 };
 808
 809 #endif