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 struct bfd_elf_version_tree;
 249
 250 /* This structure holds all the information needed to communicate
 251    between BFD and the linker when doing a link.  */
 252
 253 struct bfd_link_info
 254 {
 255   /* TRUE if BFD should generate a shared object (or a pie).  */
 256   unsigned int shared: 1;
 257
 258   /* TRUE if generating an executable, position independent or not.  */
 259   unsigned int executable : 1;
 260
 261   /* TRUE if generating a position independent executable.  */
 262   unsigned int pie: 1;
 263
 264   /* TRUE if BFD should generate a relocatable object file.  */
 265   unsigned int relocatable: 1;
 266
 267   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 268   unsigned int symbolic: 1;
 269
 270   /* TRUE if executable should not contain copy relocs.
 271      Setting this true may result in a non-sharable text segment.  */
 272   unsigned int nocopyreloc: 1;
 273
 274   /* TRUE if BFD should export all symbols in the dynamic symbol table
 275      of an executable, rather than only those used.  */
 276   unsigned int export_dynamic: 1;
 277
 278   /* TRUE if a default symbol version should be created and used for
 279      exported symbols.  */
 280   unsigned int create_default_symver: 1;
 281
 282   /* TRUE if unreferenced sections should be removed.  */
 283   unsigned int gc_sections: 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 we are loading LTO outputs.  */
 290   unsigned int loading_lto_outputs: 1;
 291
 292   /* TRUE if global symbols in discarded sections should be stripped.  */
 293   unsigned int strip_discarded: 1;
 294
 295   /* TRUE if all data symbols should be dynamic.  */
 296   unsigned int dynamic_data: 1;
 297
 298   /* Which symbols to strip.  */
 299   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 300
 301   /* Which local symbols to discard.  */
 302   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 303
 304   /* Criteria for skipping symbols when determining
 305      whether to include an object from an archive. */
 306   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 307
 308   /* What to do with unresolved symbols in an object file.
 309      When producing executables the default is GENERATE_ERROR.
 310      When producing shared libraries the default is IGNORE.  The
 311      assumption with shared libraries is that the reference will be
 312      resolved at load/execution time.  */
 313   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 314
 315   /* What to do with unresolved symbols in a shared library.
 316      The same defaults apply.  */
 317   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 318
 319   /* TRUE if shared objects should be linked directly, not shared.  */
 320   unsigned int static_link: 1;
 321
 322   /* TRUE if symbols should be retained in memory, FALSE if they
 323      should be freed and reread.  */
 324   unsigned int keep_memory: 1;
 325
 326   /* TRUE if BFD should generate relocation information in the final
 327      executable.  */
 328   unsigned int emitrelocations: 1;
 329
 330   /* TRUE if PT_GNU_RELRO segment should be created.  */
 331   unsigned int relro: 1;
 332
 333   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 334      should be created.  */
 335   unsigned int eh_frame_hdr: 1;
 336
 337   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 338   unsigned int warn_shared_textrel: 1;
 339
 340   /* TRUE if we should error when adding a DT_TEXTREL.  */
 341   unsigned int error_textrel: 1;
 342
 343   /* TRUE if .hash section should be created.  */
 344   unsigned int emit_hash: 1;
 345
 346   /* TRUE if .gnu.hash section should be created.  */
 347   unsigned int emit_gnu_hash: 1;
 348
 349   /* If TRUE reduce memory overheads, at the expense of speed. This will
 350      cause map file generation to use an O(N^2) algorithm and disable
 351      caching ELF symbol buffer.  */
 352   unsigned int reduce_memory_overheads: 1;
 353
 354   /* TRUE if the output file should be in a traditional format.  This
 355      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 356      on the output file, but may be checked when reading the input
 357      files.  */
 358   unsigned int traditional_format: 1;
 359
 360   /* TRUE if non-PLT relocs should be merged into one reloc section
 361      and sorted so that relocs against the same symbol come together.  */
 362   unsigned int combreloc: 1;
 363
 364   /* TRUE if a default symbol version should be created and used for
 365      imported symbols.  */
 366   unsigned int default_imported_symver: 1;
 367
 368   /* TRUE if the new ELF dynamic tags are enabled. */
 369   unsigned int new_dtags: 1;
 370
 371   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 372      linker created sections, TRUE if it should be omitted.  */
 373   unsigned int no_ld_generated_unwind_info: 1;
 374
 375   /* TRUE if BFD should generate a "task linked" object file,
 376      similar to relocatable but also with globals converted to
 377      statics.  */
 378   unsigned int task_link: 1;
 379
 380   /* TRUE if ok to have multiple definition.  */
 381   unsigned int allow_multiple_definition: 1;
 382
 383   /* TRUE if ok to have version with no definition.  */
 384   unsigned int allow_undefined_version: 1;
 385
 386   /* TRUE if some symbols have to be dynamic, controlled by
 387      --dynamic-list command line options.  */
 388   unsigned int dynamic: 1;
 389
 390   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 391      flags.  */
 392   unsigned int execstack: 1;
 393
 394   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 395      flags.  */
 396   unsigned int noexecstack: 1;
 397
 398   /* TRUE if we want to produced optimized output files.  This might
 399      need much more time and therefore must be explicitly selected.  */
 400   unsigned int optimize: 1;
 401
 402   /* TRUE if user should be informed of removed unreferenced sections.  */
 403   unsigned int print_gc_sections: 1;
 404
 405   /* TRUE if we should warn alternate ELF machine code.  */
 406   unsigned int warn_alternate_em: 1;
 407
 408   /* TRUE if the linker script contained an explicit PHDRS command.  */
 409   unsigned int user_phdrs: 1;
 410
 411   /* Char that may appear as the first char of a symbol, but should be
 412      skipped (like symbol_leading_char) when looking up symbols in
 413      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 414   char wrap_char;
 415
 416   /* Separator between archive and filename in linker script filespecs.  */
 417   char path_separator;
 418
 419   /* Default stack size.  Zero means default (often zero itself), -1
 420      means explicitly zero-sized.  */
 421   bfd_signed_vma stacksize;
 422
 423   /* Enable or disable target specific optimizations.
 424
 425      Not all targets have optimizations to enable.
 426
 427      Normally these optimizations are disabled by default but some targets
 428      prefer to enable them by default.  So this field is a tri-state variable.
 429      The values are:
 430
 431      zero: Enable the optimizations (either from --relax being specified on
 432        the command line or the backend's before_allocation emulation function.
 433
 434      positive: The user has requested that these optimizations be disabled.
 435        (Via the --no-relax command line option).
 436
 437      negative: The optimizations are disabled.  (Set when initializing the
 438        args_type structure in ldmain.c:main.  */
 439   signed int disable_target_specific_optimizations;
 440
 441   /* Function callbacks.  */
 442   const struct bfd_link_callbacks *callbacks;
 443
 444   /* Hash table handled by BFD.  */
 445   struct bfd_link_hash_table *hash;
 446
 447   /* Hash table of symbols to keep.  This is NULL unless strip is
 448      strip_some.  */
 449   struct bfd_hash_table *keep_hash;
 450
 451   /* Hash table of symbols to report back via the notice callback.  If
 452      this is NULL, and notice_all is FALSE, then no symbols are
 453      reported back.  */
 454   struct bfd_hash_table *notice_hash;
 455
 456   /* Hash table of symbols which are being wrapped (the --wrap linker
 457      option).  If this is NULL, no symbols are being wrapped.  */
 458   struct bfd_hash_table *wrap_hash;
 459
 460   /* Hash table of symbols which may be left unresolved during
 461      a link.  If this is NULL, no symbols can be left unresolved.  */
 462   struct bfd_hash_table *ignore_hash;
 463
 464   /* The output BFD.  */
 465   bfd *output_bfd;
 466
 467   /* The list of input BFD's involved in the link.  These are chained
 468      together via the link_next field.  */
 469   bfd *input_bfds;
 470   bfd **input_bfds_tail;
 471
 472   /* Non-NULL if .note.gnu.build-id section should be created.  */
 473   char *emit_note_gnu_build_id;
 474
 475   /* If a symbol should be created for each input BFD, this is section
 476      where those symbols should be placed.  It must be a section in
 477      the output BFD.  It may be NULL, in which case no such symbols
 478      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 479      linker command language.  */
 480   asection *create_object_symbols_section;
 481
 482   /* List of global symbol names that are starting points for marking
 483      sections against garbage collection.  */
 484   struct bfd_sym_chain *gc_sym_list;
 485
 486   /* If a base output file is wanted, then this points to it */
 487   void *base_file;
 488
 489   /* The function to call when the executable or shared object is
 490      loaded.  */
 491   const char *init_function;
 492
 493   /* The function to call when the executable or shared object is
 494      unloaded.  */
 495   const char *fini_function;
 496
 497   /* Number of relaxation passes.  Usually only one relaxation pass
 498      is needed.  But a backend can have as many relaxation passes as
 499      necessary.  During bfd_relax_section call, it is set to the
 500      current pass, starting from 0.  */
 501   int relax_pass;
 502
 503   /* Number of relaxation trips.  This number is incremented every
 504      time the relaxation pass is restarted due to a previous
 505      relaxation returning true in *AGAIN.  */
 506   int relax_trip;
 507
 508   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 509      should be generated/linked against.  Set to 1 if this feature
 510      is explicitly requested by the user, -1 if enabled by default.  */
 511   int pei386_auto_import;
 512
 513   /* Non-zero if runtime relocs for DATA items with non-zero addends
 514      in pei386 DLLs should be generated.  Set to 1 if this feature
 515      is explicitly requested by the user, -1 if enabled by default.  */
 516   int pei386_runtime_pseudo_reloc;
 517
 518   /* How many spare .dynamic DT_NULL entries should be added?  */
 519   unsigned int spare_dynamic_tags;
 520
 521   /* May be used to set DT_FLAGS for ELF. */
 522   bfd_vma flags;
 523
 524   /* May be used to set DT_FLAGS_1 for ELF. */
 525   bfd_vma flags_1;
 526
 527   /* Start and end of RELRO region.  */
 528   bfd_vma relro_start, relro_end;
 529
 530   /* List of symbols should be dynamic.  */
 531   struct bfd_elf_dynamic_list *dynamic_list;
 532
 533   /* The version information.  */
 534   struct bfd_elf_version_tree *version_info;
 535 };
 536
 537 /* This structures holds a set of callback functions.  These are called
 538    by the BFD linker routines.  Except for the info functions, the first
 539    argument to each callback function is the bfd_link_info structure
 540    being used and each function returns a boolean value.  If the
 541    function returns FALSE, then the BFD function which called it should
 542    return with a failure indication.  */
 543
 544 struct bfd_link_callbacks
 545 {
 546   /* A function which is called when an object is added from an
 547      archive.  ABFD is the archive element being added.  NAME is the
 548      name of the symbol which caused the archive element to be pulled
 549      in.  This function may set *SUBSBFD to point to an alternative
 550      BFD from which symbols should in fact be added in place of the
 551      original BFD's symbols.  */
 552   bfd_boolean (*add_archive_element)
 553     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 554   /* A function which is called when a symbol is found with multiple
 555      definitions.  H is the symbol which is defined multiple times.
 556      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 557      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 558   bfd_boolean (*multiple_definition)
 559     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 560      bfd *nbfd, asection *nsec, bfd_vma nval);
 561   /* A function which is called when a common symbol is defined
 562      multiple times.  H is the symbol appearing multiple times.
 563      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 564      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 565      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 566      is the size of the new symbol.  */
 567   bfd_boolean (*multiple_common)
 568     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 569      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 570   /* A function which is called to add a symbol to a set.  ENTRY is
 571      the link hash table entry for the set itself (e.g.,
 572      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 573      the set when generating a relocatable file, and is also used to
 574      get the size of the entry when generating an executable file.
 575      ABFD, SEC and VALUE identify the value to add to the set.  */
 576   bfd_boolean (*add_to_set)
 577     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 578      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 579   /* A function which is called when the name of a g++ constructor or
 580      destructor is found.  This is only called by some object file
 581      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 582      destructor.  This will use BFD_RELOC_CTOR when generating a
 583      relocatable file.  NAME is the name of the symbol found.  ABFD,
 584      SECTION and VALUE are the value of the symbol.  */
 585   bfd_boolean (*constructor)
 586     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 587      bfd *abfd, asection *sec, bfd_vma value);
 588   /* A function which is called to issue a linker warning.  For
 589      example, this is called when there is a reference to a warning
 590      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 591      of the symbol which triggered the warning; it may be NULL if
 592      there is none.  ABFD, SECTION and ADDRESS identify the location
 593      which trigerred the warning; either ABFD or SECTION or both may
 594      be NULL if the location is not known.  */
 595   bfd_boolean (*warning)
 596     (struct bfd_link_info *, const char *warning, const char *symbol,
 597      bfd *abfd, asection *section, bfd_vma address);
 598   /* A function which is called when a relocation is attempted against
 599      an undefined symbol.  NAME is the symbol which is undefined.
 600      ABFD, SECTION and ADDRESS identify the location from which the
 601      reference is made. IS_FATAL indicates whether an undefined symbol is
 602      a fatal error or not. In some cases SECTION may be NULL.  */
 603   bfd_boolean (*undefined_symbol)
 604     (struct bfd_link_info *, const char *name, bfd *abfd,
 605      asection *section, bfd_vma address, bfd_boolean is_fatal);
 606   /* A function which is called when a reloc overflow occurs. ENTRY is
 607      the link hash table entry for the symbol the reloc is against.
 608      NAME is the name of the local symbol or section the reloc is
 609      against, RELOC_NAME is the name of the relocation, and ADDEND is
 610      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 611      location at which the overflow occurs; if this is the result of a
 612      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 613      ABFD will be NULL.  */
 614   bfd_boolean (*reloc_overflow)
 615     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 616      const char *name, const char *reloc_name, bfd_vma addend,
 617      bfd *abfd, asection *section, bfd_vma address);
 618   /* A function which is called when a dangerous reloc is performed.
 619      MESSAGE is an appropriate message.
 620      ABFD, SECTION and ADDRESS identify the location at which the
 621      problem occurred; if this is the result of a
 622      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 623      ABFD will be NULL.  */
 624   bfd_boolean (*reloc_dangerous)
 625     (struct bfd_link_info *, const char *message,
 626      bfd *abfd, asection *section, bfd_vma address);
 627   /* A function which is called when a reloc is found to be attached
 628      to a symbol which is not being written out.  NAME is the name of
 629      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 630      the reloc; if this is the result of a
 631      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 632      ABFD will be NULL.  */
 633   bfd_boolean (*unattached_reloc)
 634     (struct bfd_link_info *, const char *name,
 635      bfd *abfd, asection *section, bfd_vma address);
 636   /* A function which is called when a symbol in notice_hash is
 637      defined or referenced.  H is the symbol.  ABFD, SECTION and
 638      ADDRESS are the (new) value of the symbol.  If SECTION is
 639      bfd_und_section, this is a reference.  FLAGS are the symbol
 640      BSF_* flags.  STRING is the name of the symbol to indirect to if
 641      the sym is indirect, or the warning string if a warning sym.  */
 642   bfd_boolean (*notice)
 643     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 644      bfd *abfd, asection *section, bfd_vma address, flagword flags,
 645      const char *string);
 646   /* Error or warning link info message.  */
 647   void (*einfo)
 648     (const char *fmt, ...);
 649   /* General link info message.  */
 650   void (*info)
 651     (const char *fmt, ...);
 652   /* Message to be printed in linker map file.  */
 653   void (*minfo)
 654     (const char *fmt, ...);
 655   /* This callback provides a chance for users of the BFD library to
 656      override its decision about whether to place two adjacent sections
 657      into the same segment.  */
 658   bfd_boolean (*override_segment_assignment)
 659     (struct bfd_link_info *, bfd * abfd,
 660      asection * current_section, asection * previous_section,
 661      bfd_boolean new_segment);
 662 };
 663 \f
 664 /* The linker builds link_order structures which tell the code how to
 665    include input data in the output file.  */
 666
 667 /* These are the types of link_order structures.  */
 668
 669 enum bfd_link_order_type
 670 {
 671   bfd_undefined_link_order,     /* Undefined.  */
 672   bfd_indirect_link_order,      /* Built from a section.  */
 673   bfd_data_link_order,          /* Set to explicit data.  */
 674   bfd_section_reloc_link_order, /* Relocate against a section.  */
 675   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 676 };
 677
 678 /* This is the link_order structure itself.  These form a chain
 679    attached to the output section whose contents they are describing.  */
 680
 681 struct bfd_link_order
 682 {
 683   /* Next link_order in chain.  */
 684   struct bfd_link_order *next;
 685   /* Type of link_order.  */
 686   enum bfd_link_order_type type;
 687   /* Offset within output section.  */
 688   bfd_vma offset;
 689   /* Size within output section.  */
 690   bfd_size_type size;
 691   /* Type specific information.  */
 692   union
 693     {
 694       struct
 695         {
 696           /* Section to include.  If this is used, then
 697              section->output_section must be the section the
 698              link_order is attached to, section->output_offset must
 699              equal the link_order offset field, and section->size
 700              must equal the link_order size field.  Maybe these
 701              restrictions should be relaxed someday.  */
 702           asection *section;
 703         } indirect;
 704       struct
 705         {
 706           /* Size of contents, or zero when contents should be filled by
 707              the architecture-dependent fill function.
 708              A non-zero value allows filling of the output section
 709              with an arbitrary repeated pattern.  */
 710           unsigned int size;
 711           /* Data to put into file.  */
 712           bfd_byte *contents;
 713         } data;
 714       struct
 715         {
 716           /* Description of reloc to generate.  Used for
 717              bfd_section_reloc_link_order and
 718              bfd_symbol_reloc_link_order.  */
 719           struct bfd_link_order_reloc *p;
 720         } reloc;
 721     } u;
 722 };
 723
 724 /* A linker order of type bfd_section_reloc_link_order or
 725    bfd_symbol_reloc_link_order means to create a reloc against a
 726    section or symbol, respectively.  This is used to implement -Ur to
 727    generate relocs for the constructor tables.  The
 728    bfd_link_order_reloc structure describes the reloc that BFD should
 729    create.  It is similar to a arelent, but I didn't use arelent
 730    because the linker does not know anything about most symbols, and
 731    any asymbol structure it creates will be partially meaningless.
 732    This information could logically be in the bfd_link_order struct,
 733    but I didn't want to waste the space since these types of relocs
 734    are relatively rare.  */
 735
 736 struct bfd_link_order_reloc
 737 {
 738   /* Reloc type.  */
 739   bfd_reloc_code_real_type reloc;
 740
 741   union
 742     {
 743       /* For type bfd_section_reloc_link_order, this is the section
 744          the reloc should be against.  This must be a section in the
 745          output BFD, not any of the input BFDs.  */
 746       asection *section;
 747       /* For type bfd_symbol_reloc_link_order, this is the name of the
 748          symbol the reloc should be against.  */
 749       const char *name;
 750     } u;
 751
 752   /* Addend to use.  The object file should contain zero.  The BFD
 753      backend is responsible for filling in the contents of the object
 754      file correctly.  For some object file formats (e.g., COFF) the
 755      addend must be stored into in the object file, and for some
 756      (e.g., SPARC a.out) it is kept in the reloc.  */
 757   bfd_vma addend;
 758 };
 759
 760 /* Allocate a new link_order for a section.  */
 761 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 762
 763 /* These structures are used to describe version information for the
 764    ELF linker.  These structures could be manipulated entirely inside
 765    BFD, but it would be a pain.  Instead, the regular linker sets up
 766    these structures, and then passes them into BFD.  */
 767
 768 /* Glob pattern for a version.  */
 769
 770 struct bfd_elf_version_expr
 771 {
 772   /* Next glob pattern for this version.  */
 773   struct bfd_elf_version_expr *next;
 774   /* Glob pattern.  */
 775   const char *pattern;
 776   /* Set if pattern is not a glob.  */
 777   unsigned int literal : 1;
 778   /* Defined by ".symver".  */
 779   unsigned int symver : 1;
 780   /* Defined by version script.  */
 781   unsigned int script : 1;
 782   /* Pattern type.  */
 783 #define BFD_ELF_VERSION_C_TYPE          1
 784 #define BFD_ELF_VERSION_CXX_TYPE        2
 785 #define BFD_ELF_VERSION_JAVA_TYPE       4
 786   unsigned int mask : 3;
 787 };
 788
 789 struct bfd_elf_version_expr_head
 790 {
 791   /* List of all patterns, both wildcards and non-wildcards.  */
 792   struct bfd_elf_version_expr *list;
 793   /* Hash table for non-wildcards.  */
 794   void *htab;
 795   /* Remaining patterns.  */
 796   struct bfd_elf_version_expr *remaining;
 797   /* What kind of pattern types are present in list (bitmask).  */
 798   unsigned int mask;
 799 };
 800
 801 /* Version dependencies.  */
 802
 803 struct bfd_elf_version_deps
 804 {
 805   /* Next dependency for this version.  */
 806   struct bfd_elf_version_deps *next;
 807   /* The version which this version depends upon.  */
 808   struct bfd_elf_version_tree *version_needed;
 809 };
 810
 811 /* A node in the version tree.  */
 812
 813 struct bfd_elf_version_tree
 814 {
 815   /* Next version.  */
 816   struct bfd_elf_version_tree *next;
 817   /* Name of this version.  */
 818   const char *name;
 819   /* Version number.  */
 820   unsigned int vernum;
 821   /* Regular expressions for global symbols in this version.  */
 822   struct bfd_elf_version_expr_head globals;
 823   /* Regular expressions for local symbols in this version.  */
 824   struct bfd_elf_version_expr_head locals;
 825   /* List of versions which this version depends upon.  */
 826   struct bfd_elf_version_deps *deps;
 827   /* Index of the version name.  This is used within BFD.  */
 828   unsigned int name_indx;
 829   /* Whether this version tree was used.  This is used within BFD.  */
 830   int used;
 831   /* Matching hook.  */
 832   struct bfd_elf_version_expr *(*match)
 833     (struct bfd_elf_version_expr_head *head,
 834      struct bfd_elf_version_expr *prev, const char *sym);
 835 };
 836
 837 struct bfd_elf_dynamic_list
 838 {
 839   struct bfd_elf_version_expr_head head;
 840   struct bfd_elf_version_expr *(*match)
 841     (struct bfd_elf_version_expr_head *head,
 842      struct bfd_elf_version_expr *prev, const char *sym);
 843 };
 844
 845 #endif