include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2014 Free Software Foundation, Inc.
   3    Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
   4
   5    This file is part of BFD, the Binary File Descriptor library.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    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_symbols
  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 struct bfd_link_hash_common_entry
  78   {
  79     unsigned int alignment_power;       /* Alignment.  */
  80     asection *section;          /* Symbol section.  */
  81   };
  82
  83 /* The linking routines use a hash table which uses this structure for
  84    its elements.  */
  85
  86 struct bfd_link_hash_entry
  87 {
  88   /* Base hash table entry structure.  */
  89   struct bfd_hash_entry root;
  90
  91   /* Type of this entry.  */
  92   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
  93
  94   unsigned int non_ir_ref : 1;
  95
  96   /* A union of information depending upon the type.  */
  97   union
  98     {
  99       /* Nothing is kept for bfd_hash_new.  */
 100       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 101       struct
 102         {
 103           /* Undefined and common symbols are kept in a linked list through
 104              this field.  This field is present in all of the union element
 105              so that we don't need to remove entries from the list when we
 106              change their type.  Removing entries would either require the
 107              list to be doubly linked, which would waste more memory, or
 108              require a traversal.  When an undefined or common symbol is
 109              created, it should be added to this list, the head of which is in
 110              the link hash table itself.  As symbols are defined, they need
 111              not be removed from the list; anything which reads the list must
 112              doublecheck the symbol type.
 113
 114              Weak symbols are not kept on this list.
 115
 116              Defined and defweak symbols use this field as a reference marker.
 117              If the field is not NULL, or this structure is the tail of the
 118              undefined symbol list, the symbol has been referenced.  If the
 119              symbol is undefined and becomes defined, this field will
 120              automatically be non-NULL since the symbol will have been on the
 121              undefined symbol list.  */
 122           struct bfd_link_hash_entry *next;
 123           bfd *abfd;            /* BFD symbol was found in.  */
 124         } undef;
 125       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 126       struct
 127         {
 128           struct bfd_link_hash_entry *next;
 129           asection *section;    /* Symbol section.  */
 130           bfd_vma value;        /* Symbol value.  */
 131         } def;
 132       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 133       struct
 134         {
 135           struct bfd_link_hash_entry *next;
 136           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 137           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 138         } i;
 139       /* bfd_link_hash_common.  */
 140       struct
 141         {
 142           struct bfd_link_hash_entry *next;
 143           /* The linker needs to know three things about common
 144              symbols: the size, the alignment, and the section in
 145              which the symbol should be placed.  We store the size
 146              here, and we allocate a small structure to hold the
 147              section and the alignment.  The alignment is stored as a
 148              power of two.  We don't store all the information
 149              directly because we don't want to increase the size of
 150              the union; this structure is a major space user in the
 151              linker.  */
 152           struct bfd_link_hash_common_entry *p;
 153           bfd_size_type size;   /* Common symbol size.  */
 154         } c;
 155     } u;
 156 };
 157
 158 /* This is the link hash table.  It is a derived class of
 159    bfd_hash_table.  */
 160
 161 struct bfd_link_hash_table
 162 {
 163   /* The hash table itself.  */
 164   struct bfd_hash_table table;
 165   /* A linked list of undefined and common symbols, linked through the
 166      next field in the bfd_link_hash_entry structure.  */
 167   struct bfd_link_hash_entry *undefs;
 168   /* Entries are added to the tail of the undefs list.  */
 169   struct bfd_link_hash_entry *undefs_tail;
 170   /* Function to free the hash table on closing BFD.  */
 171   void (*hash_table_free) (bfd *);
 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 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 192    and the remainder is found in wrap_hash, return the real symbol.  */
 193
 194 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 195   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 196
 197 /* Traverse a link hash table.  */
 198 extern void bfd_link_hash_traverse
 199   (struct bfd_link_hash_table *,
 200     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 201     void *);
 202
 203 /* Add an entry to the undefs list.  */
 204 extern void bfd_link_add_undef
 205   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 206
 207 /* Remove symbols from the undefs list that don't belong there.  */
 208 extern void bfd_link_repair_undef_list
 209   (struct bfd_link_hash_table *table);
 210
 211 /* Read symbols and cache symbol pointer array in outsymbols.  */
 212 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 213
 214 struct bfd_sym_chain
 215 {
 216   struct bfd_sym_chain *next;
 217   const char *name;
 218 };
 219 \f
 220 /* How to handle unresolved symbols.
 221    There are four possibilities which are enumerated below:  */
 222 enum report_method
 223 {
 224   /* This is the initial value when then link_info structure is created.
 225      It allows the various stages of the linker to determine whether they
 226      allowed to set the value.  */
 227   RM_NOT_YET_SET = 0,
 228   RM_IGNORE,
 229   RM_GENERATE_WARNING,
 230   RM_GENERATE_ERROR
 231 };
 232
 233 typedef enum {with_flags, without_flags} flag_type;
 234
 235 /* A section flag list.  */
 236 struct flag_info_list
 237 {
 238   flag_type with;
 239   const char *name;
 240   bfd_boolean valid;
 241   struct flag_info_list *next;
 242 };
 243
 244 /* Section flag info.  */
 245 struct flag_info
 246 {
 247   flagword only_with_flags;
 248   flagword not_with_flags;
 249   struct flag_info_list *flag_list;
 250   bfd_boolean flags_initialized;
 251 };
 252
 253 struct bfd_elf_dynamic_list;
 254 struct bfd_elf_version_tree;
 255
 256 /* This structure holds all the information needed to communicate
 257    between BFD and the linker when doing a link.  */
 258
 259 struct bfd_link_info
 260 {
 261   /* TRUE if BFD should generate a shared object (or a pie).  */
 262   unsigned int shared: 1;
 263
 264   /* TRUE if generating an executable, position independent or not.  */
 265   unsigned int executable : 1;
 266
 267   /* TRUE if generating a position independent executable.  */
 268   unsigned int pie: 1;
 269
 270   /* TRUE if BFD should generate a relocatable object file.  */
 271   unsigned int relocatable: 1;
 272
 273   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 274   unsigned int symbolic: 1;
 275
 276   /* TRUE if executable should not contain copy relocs.
 277      Setting this true may result in a non-sharable text segment.  */
 278   unsigned int nocopyreloc: 1;
 279
 280   /* TRUE if BFD should export all symbols in the dynamic symbol table
 281      of an executable, rather than only those used.  */
 282   unsigned int export_dynamic: 1;
 283
 284   /* TRUE if a default symbol version should be created and used for
 285      exported symbols.  */
 286   unsigned int create_default_symver: 1;
 287
 288   /* TRUE if unreferenced sections should be removed.  */
 289   unsigned int gc_sections: 1;
 290
 291   /* TRUE if every symbol should be reported back via the notice
 292      callback.  */
 293   unsigned int notice_all: 1;
 294
 295   /* TRUE if we are loading LTO outputs.  */
 296   unsigned int loading_lto_outputs: 1;
 297
 298   /* TRUE if global symbols in discarded sections should be stripped.  */
 299   unsigned int strip_discarded: 1;
 300
 301   /* TRUE if all data symbols should be dynamic.  */
 302   unsigned int dynamic_data: 1;
 303
 304   /* Which symbols to strip.  */
 305   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 306
 307   /* Which local symbols to discard.  */
 308   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 309
 310   /* Criteria for skipping symbols when determining
 311      whether to include an object from an archive. */
 312   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 313
 314   /* What to do with unresolved symbols in an object file.
 315      When producing executables the default is GENERATE_ERROR.
 316      When producing shared libraries the default is IGNORE.  The
 317      assumption with shared libraries is that the reference will be
 318      resolved at load/execution time.  */
 319   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 320
 321   /* What to do with unresolved symbols in a shared library.
 322      The same defaults apply.  */
 323   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 324
 325   /* TRUE if shared objects should be linked directly, not shared.  */
 326   unsigned int static_link: 1;
 327
 328   /* TRUE if symbols should be retained in memory, FALSE if they
 329      should be freed and reread.  */
 330   unsigned int keep_memory: 1;
 331
 332   /* TRUE if BFD should generate relocation information in the final
 333      executable.  */
 334   unsigned int emitrelocations: 1;
 335
 336   /* TRUE if PT_GNU_RELRO segment should be created.  */
 337   unsigned int relro: 1;
 338
 339   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 340      should be created.  */
 341   unsigned int eh_frame_hdr: 1;
 342
 343   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 344   unsigned int warn_shared_textrel: 1;
 345
 346   /* TRUE if we should error when adding a DT_TEXTREL.  */
 347   unsigned int error_textrel: 1;
 348
 349   /* TRUE if .hash section should be created.  */
 350   unsigned int emit_hash: 1;
 351
 352   /* TRUE if .gnu.hash section should be created.  */
 353   unsigned int emit_gnu_hash: 1;
 354
 355   /* If TRUE reduce memory overheads, at the expense of speed. This will
 356      cause map file generation to use an O(N^2) algorithm and disable
 357      caching ELF symbol buffer.  */
 358   unsigned int reduce_memory_overheads: 1;
 359
 360   /* TRUE if the output file should be in a traditional format.  This
 361      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 362      on the output file, but may be checked when reading the input
 363      files.  */
 364   unsigned int traditional_format: 1;
 365
 366   /* TRUE if non-PLT relocs should be merged into one reloc section
 367      and sorted so that relocs against the same symbol come together.  */
 368   unsigned int combreloc: 1;
 369
 370   /* TRUE if a default symbol version should be created and used for
 371      imported symbols.  */
 372   unsigned int default_imported_symver: 1;
 373
 374   /* TRUE if the new ELF dynamic tags are enabled. */
 375   unsigned int new_dtags: 1;
 376
 377   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 378      linker created sections, TRUE if it should be omitted.  */
 379   unsigned int no_ld_generated_unwind_info: 1;
 380
 381   /* TRUE if BFD should generate a "task linked" object file,
 382      similar to relocatable but also with globals converted to
 383      statics.  */
 384   unsigned int task_link: 1;
 385
 386   /* TRUE if ok to have multiple definition.  */
 387   unsigned int allow_multiple_definition: 1;
 388
 389   /* TRUE if ok to have version with no definition.  */
 390   unsigned int allow_undefined_version: 1;
 391
 392   /* TRUE if some symbols have to be dynamic, controlled by
 393      --dynamic-list command line options.  */
 394   unsigned int dynamic: 1;
 395
 396   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 397      flags.  */
 398   unsigned int execstack: 1;
 399
 400   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 401      flags.  */
 402   unsigned int noexecstack: 1;
 403
 404   /* TRUE if we want to produced optimized output files.  This might
 405      need much more time and therefore must be explicitly selected.  */
 406   unsigned int optimize: 1;
 407
 408   /* TRUE if user should be informed of removed unreferenced sections.  */
 409   unsigned int print_gc_sections: 1;
 410
 411   /* TRUE if we should warn alternate ELF machine code.  */
 412   unsigned int warn_alternate_em: 1;
 413
 414   /* TRUE if the linker script contained an explicit PHDRS command.  */
 415   unsigned int user_phdrs: 1;
 416
 417   /* Char that may appear as the first char of a symbol, but should be
 418      skipped (like symbol_leading_char) when looking up symbols in
 419      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 420   char wrap_char;
 421
 422   /* Separator between archive and filename in linker script filespecs.  */
 423   char path_separator;
 424
 425   /* Default stack size.  Zero means default (often zero itself), -1
 426      means explicitly zero-sized.  */
 427   bfd_signed_vma stacksize;
 428
 429   /* Enable or disable target specific optimizations.
 430
 431      Not all targets have optimizations to enable.
 432
 433      Normally these optimizations are disabled by default but some targets
 434      prefer to enable them by default.  So this field is a tri-state variable.
 435      The values are:
 436
 437      zero: Enable the optimizations (either from --relax being specified on
 438        the command line or the backend's before_allocation emulation function.
 439
 440      positive: The user has requested that these optimizations be disabled.
 441        (Via the --no-relax command line option).
 442
 443      negative: The optimizations are disabled.  (Set when initializing the
 444        args_type structure in ldmain.c:main.  */
 445   signed int disable_target_specific_optimizations;
 446
 447   /* Function callbacks.  */
 448   const struct bfd_link_callbacks *callbacks;
 449
 450   /* Hash table handled by BFD.  */
 451   struct bfd_link_hash_table *hash;
 452
 453   /* Hash table of symbols to keep.  This is NULL unless strip is
 454      strip_some.  */
 455   struct bfd_hash_table *keep_hash;
 456
 457   /* Hash table of symbols to report back via the notice callback.  If
 458      this is NULL, and notice_all is FALSE, then no symbols are
 459      reported back.  */
 460   struct bfd_hash_table *notice_hash;
 461
 462   /* Hash table of symbols which are being wrapped (the --wrap linker
 463      option).  If this is NULL, no symbols are being wrapped.  */
 464   struct bfd_hash_table *wrap_hash;
 465
 466   /* Hash table of symbols which may be left unresolved during
 467      a link.  If this is NULL, no symbols can be left unresolved.  */
 468   struct bfd_hash_table *ignore_hash;
 469
 470   /* The output BFD.  */
 471   bfd *output_bfd;
 472
 473   /* The list of input BFD's involved in the link.  These are chained
 474      together via the link.next field.  */
 475   bfd *input_bfds;
 476   bfd **input_bfds_tail;
 477
 478   /* If a symbol should be created for each input BFD, this is section
 479      where those symbols should be placed.  It must be a section in
 480      the output BFD.  It may be NULL, in which case no such symbols
 481      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 482      linker command language.  */
 483   asection *create_object_symbols_section;
 484
 485   /* List of global symbol names that are starting points for marking
 486      sections against garbage collection.  */
 487   struct bfd_sym_chain *gc_sym_list;
 488
 489   /* If a base output file is wanted, then this points to it */
 490   void *base_file;
 491
 492   /* The function to call when the executable or shared object is
 493      loaded.  */
 494   const char *init_function;
 495
 496   /* The function to call when the executable or shared object is
 497      unloaded.  */
 498   const char *fini_function;
 499
 500   /* Number of relaxation passes.  Usually only one relaxation pass
 501      is needed.  But a backend can have as many relaxation passes as
 502      necessary.  During bfd_relax_section call, it is set to the
 503      current pass, starting from 0.  */
 504   int relax_pass;
 505
 506   /* Number of relaxation trips.  This number is incremented every
 507      time the relaxation pass is restarted due to a previous
 508      relaxation returning true in *AGAIN.  */
 509   int relax_trip;
 510
 511   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 512      should be generated/linked against.  Set to 1 if this feature
 513      is explicitly requested by the user, -1 if enabled by default.  */
 514   int pei386_auto_import;
 515
 516   /* Non-zero if runtime relocs for DATA items with non-zero addends
 517      in pei386 DLLs should be generated.  Set to 1 if this feature
 518      is explicitly requested by the user, -1 if enabled by default.  */
 519   int pei386_runtime_pseudo_reloc;
 520
 521   /* How many spare .dynamic DT_NULL entries should be added?  */
 522   unsigned int spare_dynamic_tags;
 523
 524   /* May be used to set DT_FLAGS for ELF. */
 525   bfd_vma flags;
 526
 527   /* May be used to set DT_FLAGS_1 for ELF. */
 528   bfd_vma flags_1;
 529
 530   /* Start and end of RELRO region.  */
 531   bfd_vma relro_start, relro_end;
 532
 533   /* List of symbols should be dynamic.  */
 534   struct bfd_elf_dynamic_list *dynamic_list;
 535
 536   /* The version information.  */
 537   struct bfd_elf_version_tree *version_info;
 538 };
 539
 540 /* This structures holds a set of callback functions.  These are called
 541    by the BFD linker routines.  Except for the info functions, the first
 542    argument to each callback function is the bfd_link_info structure
 543    being used and each function returns a boolean value.  If the
 544    function returns FALSE, then the BFD function which called it should
 545    return with a failure indication.  */
 546
 547 struct bfd_link_callbacks
 548 {
 549   /* A function which is called when an object is added from an
 550      archive.  ABFD is the archive element being added.  NAME is the
 551      name of the symbol which caused the archive element to be pulled
 552      in.  This function may set *SUBSBFD to point to an alternative
 553      BFD from which symbols should in fact be added in place of the
 554      original BFD's symbols.  */
 555   bfd_boolean (*add_archive_element)
 556     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 557   /* A function which is called when a symbol is found with multiple
 558      definitions.  H is the symbol which is defined multiple times.
 559      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 560      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 561   bfd_boolean (*multiple_definition)
 562     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 563      bfd *nbfd, asection *nsec, bfd_vma nval);
 564   /* A function which is called when a common symbol is defined
 565      multiple times.  H is the symbol appearing multiple times.
 566      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 567      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 568      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 569      is the size of the new symbol.  */
 570   bfd_boolean (*multiple_common)
 571     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 572      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 573   /* A function which is called to add a symbol to a set.  ENTRY is
 574      the link hash table entry for the set itself (e.g.,
 575      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 576      the set when generating a relocatable file, and is also used to
 577      get the size of the entry when generating an executable file.
 578      ABFD, SEC and VALUE identify the value to add to the set.  */
 579   bfd_boolean (*add_to_set)
 580     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 581      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 582   /* A function which is called when the name of a g++ constructor or
 583      destructor is found.  This is only called by some object file
 584      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 585      destructor.  This will use BFD_RELOC_CTOR when generating a
 586      relocatable file.  NAME is the name of the symbol found.  ABFD,
 587      SECTION and VALUE are the value of the symbol.  */
 588   bfd_boolean (*constructor)
 589     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 590      bfd *abfd, asection *sec, bfd_vma value);
 591   /* A function which is called to issue a linker warning.  For
 592      example, this is called when there is a reference to a warning
 593      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 594      of the symbol which triggered the warning; it may be NULL if
 595      there is none.  ABFD, SECTION and ADDRESS identify the location
 596      which trigerred the warning; either ABFD or SECTION or both may
 597      be NULL if the location is not known.  */
 598   bfd_boolean (*warning)
 599     (struct bfd_link_info *, const char *warning, const char *symbol,
 600      bfd *abfd, asection *section, bfd_vma address);
 601   /* A function which is called when a relocation is attempted against
 602      an undefined symbol.  NAME is the symbol which is undefined.
 603      ABFD, SECTION and ADDRESS identify the location from which the
 604      reference is made. IS_FATAL indicates whether an undefined symbol is
 605      a fatal error or not. In some cases SECTION may be NULL.  */
 606   bfd_boolean (*undefined_symbol)
 607     (struct bfd_link_info *, const char *name, bfd *abfd,
 608      asection *section, bfd_vma address, bfd_boolean is_fatal);
 609   /* A function which is called when a reloc overflow occurs. ENTRY is
 610      the link hash table entry for the symbol the reloc is against.
 611      NAME is the name of the local symbol or section the reloc is
 612      against, RELOC_NAME is the name of the relocation, and ADDEND is
 613      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 614      location at which the overflow occurs; if this is the result of a
 615      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 616      ABFD will be NULL.  */
 617   bfd_boolean (*reloc_overflow)
 618     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 619      const char *name, const char *reloc_name, bfd_vma addend,
 620      bfd *abfd, asection *section, bfd_vma address);
 621   /* A function which is called when a dangerous reloc is performed.
 622      MESSAGE is an appropriate message.
 623      ABFD, SECTION and ADDRESS identify the location at which the
 624      problem occurred; if this is the result of a
 625      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 626      ABFD will be NULL.  */
 627   bfd_boolean (*reloc_dangerous)
 628     (struct bfd_link_info *, const char *message,
 629      bfd *abfd, asection *section, bfd_vma address);
 630   /* A function which is called when a reloc is found to be attached
 631      to a symbol which is not being written out.  NAME is the name of
 632      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 633      the reloc; if this is the result of a
 634      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 635      ABFD will be NULL.  */
 636   bfd_boolean (*unattached_reloc)
 637     (struct bfd_link_info *, const char *name,
 638      bfd *abfd, asection *section, bfd_vma address);
 639   /* A function which is called when a symbol in notice_hash is
 640      defined or referenced.  H is the symbol.  ABFD, SECTION and
 641      ADDRESS are the (new) value of the symbol.  If SECTION is
 642      bfd_und_section, this is a reference.  FLAGS are the symbol
 643      BSF_* flags.  STRING is the name of the symbol to indirect to if
 644      the sym is indirect, or the warning string if a warning sym.  */
 645   bfd_boolean (*notice)
 646     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 647      bfd *abfd, asection *section, bfd_vma address, flagword flags,
 648      const char *string);
 649   /* Error or warning link info message.  */
 650   void (*einfo)
 651     (const char *fmt, ...);
 652   /* General link info message.  */
 653   void (*info)
 654     (const char *fmt, ...);
 655   /* Message to be printed in linker map file.  */
 656   void (*minfo)
 657     (const char *fmt, ...);
 658   /* This callback provides a chance for users of the BFD library to
 659      override its decision about whether to place two adjacent sections
 660      into the same segment.  */
 661   bfd_boolean (*override_segment_assignment)
 662     (struct bfd_link_info *, bfd * abfd,
 663      asection * current_section, asection * previous_section,
 664      bfd_boolean new_segment);
 665 };
 666 \f
 667 /* The linker builds link_order structures which tell the code how to
 668    include input data in the output file.  */
 669
 670 /* These are the types of link_order structures.  */
 671
 672 enum bfd_link_order_type
 673 {
 674   bfd_undefined_link_order,     /* Undefined.  */
 675   bfd_indirect_link_order,      /* Built from a section.  */
 676   bfd_data_link_order,          /* Set to explicit data.  */
 677   bfd_section_reloc_link_order, /* Relocate against a section.  */
 678   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 679 };
 680
 681 /* This is the link_order structure itself.  These form a chain
 682    attached to the output section whose contents they are describing.  */
 683
 684 struct bfd_link_order
 685 {
 686   /* Next link_order in chain.  */
 687   struct bfd_link_order *next;
 688   /* Type of link_order.  */
 689   enum bfd_link_order_type type;
 690   /* Offset within output section.  */
 691   bfd_vma offset;
 692   /* Size within output section.  */
 693   bfd_size_type size;
 694   /* Type specific information.  */
 695   union
 696     {
 697       struct
 698         {
 699           /* Section to include.  If this is used, then
 700              section->output_section must be the section the
 701              link_order is attached to, section->output_offset must
 702              equal the link_order offset field, and section->size
 703              must equal the link_order size field.  Maybe these
 704              restrictions should be relaxed someday.  */
 705           asection *section;
 706         } indirect;
 707       struct
 708         {
 709           /* Size of contents, or zero when contents should be filled by
 710              the architecture-dependent fill function.
 711              A non-zero value allows filling of the output section
 712              with an arbitrary repeated pattern.  */
 713           unsigned int size;
 714           /* Data to put into file.  */
 715           bfd_byte *contents;
 716         } data;
 717       struct
 718         {
 719           /* Description of reloc to generate.  Used for
 720              bfd_section_reloc_link_order and
 721              bfd_symbol_reloc_link_order.  */
 722           struct bfd_link_order_reloc *p;
 723         } reloc;
 724     } u;
 725 };
 726
 727 /* A linker order of type bfd_section_reloc_link_order or
 728    bfd_symbol_reloc_link_order means to create a reloc against a
 729    section or symbol, respectively.  This is used to implement -Ur to
 730    generate relocs for the constructor tables.  The
 731    bfd_link_order_reloc structure describes the reloc that BFD should
 732    create.  It is similar to a arelent, but I didn't use arelent
 733    because the linker does not know anything about most symbols, and
 734    any asymbol structure it creates will be partially meaningless.
 735    This information could logically be in the bfd_link_order struct,
 736    but I didn't want to waste the space since these types of relocs
 737    are relatively rare.  */
 738
 739 struct bfd_link_order_reloc
 740 {
 741   /* Reloc type.  */
 742   bfd_reloc_code_real_type reloc;
 743
 744   union
 745     {
 746       /* For type bfd_section_reloc_link_order, this is the section
 747          the reloc should be against.  This must be a section in the
 748          output BFD, not any of the input BFDs.  */
 749       asection *section;
 750       /* For type bfd_symbol_reloc_link_order, this is the name of the
 751          symbol the reloc should be against.  */
 752       const char *name;
 753     } u;
 754
 755   /* Addend to use.  The object file should contain zero.  The BFD
 756      backend is responsible for filling in the contents of the object
 757      file correctly.  For some object file formats (e.g., COFF) the
 758      addend must be stored into in the object file, and for some
 759      (e.g., SPARC a.out) it is kept in the reloc.  */
 760   bfd_vma addend;
 761 };
 762
 763 /* Allocate a new link_order for a section.  */
 764 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 765
 766 /* These structures are used to describe version information for the
 767    ELF linker.  These structures could be manipulated entirely inside
 768    BFD, but it would be a pain.  Instead, the regular linker sets up
 769    these structures, and then passes them into BFD.  */
 770
 771 /* Glob pattern for a version.  */
 772
 773 struct bfd_elf_version_expr
 774 {
 775   /* Next glob pattern for this version.  */
 776   struct bfd_elf_version_expr *next;
 777   /* Glob pattern.  */
 778   const char *pattern;
 779   /* Set if pattern is not a glob.  */
 780   unsigned int literal : 1;
 781   /* Defined by ".symver".  */
 782   unsigned int symver : 1;
 783   /* Defined by version script.  */
 784   unsigned int script : 1;
 785   /* Pattern type.  */
 786 #define BFD_ELF_VERSION_C_TYPE          1
 787 #define BFD_ELF_VERSION_CXX_TYPE        2
 788 #define BFD_ELF_VERSION_JAVA_TYPE       4
 789   unsigned int mask : 3;
 790 };
 791
 792 struct bfd_elf_version_expr_head
 793 {
 794   /* List of all patterns, both wildcards and non-wildcards.  */
 795   struct bfd_elf_version_expr *list;
 796   /* Hash table for non-wildcards.  */
 797   void *htab;
 798   /* Remaining patterns.  */
 799   struct bfd_elf_version_expr *remaining;
 800   /* What kind of pattern types are present in list (bitmask).  */
 801   unsigned int mask;
 802 };
 803
 804 /* Version dependencies.  */
 805
 806 struct bfd_elf_version_deps
 807 {
 808   /* Next dependency for this version.  */
 809   struct bfd_elf_version_deps *next;
 810   /* The version which this version depends upon.  */
 811   struct bfd_elf_version_tree *version_needed;
 812 };
 813
 814 /* A node in the version tree.  */
 815
 816 struct bfd_elf_version_tree
 817 {
 818   /* Next version.  */
 819   struct bfd_elf_version_tree *next;
 820   /* Name of this version.  */
 821   const char *name;
 822   /* Version number.  */
 823   unsigned int vernum;
 824   /* Regular expressions for global symbols in this version.  */
 825   struct bfd_elf_version_expr_head globals;
 826   /* Regular expressions for local symbols in this version.  */
 827   struct bfd_elf_version_expr_head locals;
 828   /* List of versions which this version depends upon.  */
 829   struct bfd_elf_version_deps *deps;
 830   /* Index of the version name.  This is used within BFD.  */
 831   unsigned int name_indx;
 832   /* Whether this version tree was used.  This is used within BFD.  */
 833   int used;
 834   /* Matching hook.  */
 835   struct bfd_elf_version_expr *(*match)
 836     (struct bfd_elf_version_expr_head *head,
 837      struct bfd_elf_version_expr *prev, const char *sym);
 838 };
 839
 840 struct bfd_elf_dynamic_list
 841 {
 842   struct bfd_elf_version_expr_head head;
 843   struct bfd_elf_version_expr *(*match)
 844     (struct bfd_elf_version_expr_head *head,
 845      struct bfd_elf_version_expr *prev, const char *sym);
 846 };
 847
 848 #endif