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   /* The type of the link hash table.  */
 171   enum bfd_link_hash_table_type type;
 172 };
 173
 174 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 175    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 176    the real symbol.  */
 177 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 178   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 179    bfd_boolean copy, bfd_boolean follow);
 180
 181 /* Look up an entry in the main linker hash table if the symbol might
 182    be wrapped.  This should only be used for references to an
 183    undefined symbol, not for definitions of a symbol.  */
 184
 185 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 186   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 187    bfd_boolean, bfd_boolean);
 188
 189 /* Traverse a link hash table.  */
 190 extern void bfd_link_hash_traverse
 191   (struct bfd_link_hash_table *,
 192     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 193     void *);
 194
 195 /* Add an entry to the undefs list.  */
 196 extern void bfd_link_add_undef
 197   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 198
 199 /* Remove symbols from the undefs list that don't belong there.  */
 200 extern void bfd_link_repair_undef_list
 201   (struct bfd_link_hash_table *table);
 202
 203 /* Read symbols and cache symbol pointer array in outsymbols.  */
 204 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 205
 206 struct bfd_sym_chain
 207 {
 208   struct bfd_sym_chain *next;
 209   const char *name;
 210 };
 211 \f
 212 /* How to handle unresolved symbols.
 213    There are four possibilities which are enumerated below:  */
 214 enum report_method
 215 {
 216   /* This is the initial value when then link_info structure is created.
 217      It allows the various stages of the linker to determine whether they
 218      allowed to set the value.  */
 219   RM_NOT_YET_SET = 0,
 220   RM_IGNORE,
 221   RM_GENERATE_WARNING,
 222   RM_GENERATE_ERROR
 223 };
 224
 225 typedef enum {with_flags, without_flags} flag_type;
 226
 227 /* A section flag list.  */
 228 struct flag_info_list
 229 {
 230   flag_type with;
 231   const char *name;
 232   bfd_boolean valid;
 233   struct flag_info_list *next;
 234 };
 235
 236 /* Section flag info.  */
 237 struct flag_info
 238 {
 239   flagword only_with_flags;
 240   flagword not_with_flags;
 241   struct flag_info_list *flag_list;
 242   bfd_boolean flags_initialized;
 243 };
 244
 245 struct bfd_elf_dynamic_list;
 246 struct bfd_elf_version_tree;
 247
 248 /* This structure holds all the information needed to communicate
 249    between BFD and the linker when doing a link.  */
 250
 251 struct bfd_link_info
 252 {
 253   /* TRUE if BFD should generate a shared object (or a pie).  */
 254   unsigned int shared: 1;
 255
 256   /* TRUE if generating an executable, position independent or not.  */
 257   unsigned int executable : 1;
 258
 259   /* TRUE if generating a position independent executable.  */
 260   unsigned int pie: 1;
 261
 262   /* TRUE if BFD should generate a relocatable object file.  */
 263   unsigned int relocatable: 1;
 264
 265   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 266   unsigned int symbolic: 1;
 267
 268   /* TRUE if executable should not contain copy relocs.
 269      Setting this true may result in a non-sharable text segment.  */
 270   unsigned int nocopyreloc: 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 a default symbol version should be created and used for
 277      exported symbols.  */
 278   unsigned int create_default_symver: 1;
 279
 280   /* TRUE if unreferenced sections should be removed.  */
 281   unsigned int gc_sections: 1;
 282
 283   /* TRUE if every symbol should be reported back via the notice
 284      callback.  */
 285   unsigned int notice_all: 1;
 286
 287   /* TRUE if we are loading LTO outputs.  */
 288   unsigned int loading_lto_outputs: 1;
 289
 290   /* TRUE if global symbols in discarded sections should be stripped.  */
 291   unsigned int strip_discarded: 1;
 292
 293   /* TRUE if all data symbols should be dynamic.  */
 294   unsigned int dynamic_data: 1;
 295
 296   /* Which symbols to strip.  */
 297   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 298
 299   /* Which local symbols to discard.  */
 300   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 301
 302   /* Criteria for skipping symbols when determining
 303      whether to include an object from an archive. */
 304   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 305
 306   /* What to do with unresolved symbols in an object file.
 307      When producing executables the default is GENERATE_ERROR.
 308      When producing shared libraries the default is IGNORE.  The
 309      assumption with shared libraries is that the reference will be
 310      resolved at load/execution time.  */
 311   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 312
 313   /* What to do with unresolved symbols in a shared library.
 314      The same defaults apply.  */
 315   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 316
 317   /* TRUE if shared objects should be linked directly, not shared.  */
 318   unsigned int static_link: 1;
 319
 320   /* TRUE if symbols should be retained in memory, FALSE if they
 321      should be freed and reread.  */
 322   unsigned int keep_memory: 1;
 323
 324   /* TRUE if BFD should generate relocation information in the final
 325      executable.  */
 326   unsigned int emitrelocations: 1;
 327
 328   /* TRUE if PT_GNU_RELRO segment should be created.  */
 329   unsigned int relro: 1;
 330
 331   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 332      should be created.  */
 333   unsigned int eh_frame_hdr: 1;
 334
 335   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 336   unsigned int warn_shared_textrel: 1;
 337
 338   /* TRUE if we should error when adding a DT_TEXTREL.  */
 339   unsigned int error_textrel: 1;
 340
 341   /* TRUE if .hash section should be created.  */
 342   unsigned int emit_hash: 1;
 343
 344   /* TRUE if .gnu.hash section should be created.  */
 345   unsigned int emit_gnu_hash: 1;
 346
 347   /* If TRUE reduce memory overheads, at the expense of speed. This will
 348      cause map file generation to use an O(N^2) algorithm and disable
 349      caching ELF symbol buffer.  */
 350   unsigned int reduce_memory_overheads: 1;
 351
 352   /* TRUE if the output file should be in a traditional format.  This
 353      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 354      on the output file, but may be checked when reading the input
 355      files.  */
 356   unsigned int traditional_format: 1;
 357
 358   /* TRUE if non-PLT relocs should be merged into one reloc section
 359      and sorted so that relocs against the same symbol come together.  */
 360   unsigned int combreloc: 1;
 361
 362   /* TRUE if a default symbol version should be created and used for
 363      imported symbols.  */
 364   unsigned int default_imported_symver: 1;
 365
 366   /* TRUE if the new ELF dynamic tags are enabled. */
 367   unsigned int new_dtags: 1;
 368
 369   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 370      linker created sections, TRUE if it should be omitted.  */
 371   unsigned int no_ld_generated_unwind_info: 1;
 372
 373   /* TRUE if BFD should generate a "task linked" object file,
 374      similar to relocatable but also with globals converted to
 375      statics.  */
 376   unsigned int task_link: 1;
 377
 378   /* TRUE if ok to have multiple definition.  */
 379   unsigned int allow_multiple_definition: 1;
 380
 381   /* TRUE if ok to have version with no definition.  */
 382   unsigned int allow_undefined_version: 1;
 383
 384   /* TRUE if some symbols have to be dynamic, controlled by
 385      --dynamic-list command line options.  */
 386   unsigned int dynamic: 1;
 387
 388   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 389      flags.  */
 390   unsigned int execstack: 1;
 391
 392   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 393      flags.  */
 394   unsigned int noexecstack: 1;
 395
 396   /* TRUE if we want to produced optimized output files.  This might
 397      need much more time and therefore must be explicitly selected.  */
 398   unsigned int optimize: 1;
 399
 400   /* TRUE if user should be informed of removed unreferenced sections.  */
 401   unsigned int print_gc_sections: 1;
 402
 403   /* TRUE if we should warn alternate ELF machine code.  */
 404   unsigned int warn_alternate_em: 1;
 405
 406   /* TRUE if the linker script contained an explicit PHDRS command.  */
 407   unsigned int user_phdrs: 1;
 408
 409   /* Char that may appear as the first char of a symbol, but should be
 410      skipped (like symbol_leading_char) when looking up symbols in
 411      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 412   char wrap_char;
 413
 414   /* Separator between archive and filename in linker script filespecs.  */
 415   char path_separator;
 416
 417   /* Default stack size.  Zero means default (often zero itself), -1
 418      means explicitly zero-sized.  */
 419   bfd_signed_vma stacksize;
 420
 421   /* Enable or disable target specific optimizations.
 422
 423      Not all targets have optimizations to enable.
 424
 425      Normally these optimizations are disabled by default but some targets
 426      prefer to enable them by default.  So this field is a tri-state variable.
 427      The values are:
 428
 429      zero: Enable the optimizations (either from --relax being specified on
 430        the command line or the backend's before_allocation emulation function.
 431
 432      positive: The user has requested that these optimizations be disabled.
 433        (Via the --no-relax command line option).
 434
 435      negative: The optimizations are disabled.  (Set when initializing the
 436        args_type structure in ldmain.c:main.  */
 437   signed int disable_target_specific_optimizations;
 438
 439   /* Function callbacks.  */
 440   const struct bfd_link_callbacks *callbacks;
 441
 442   /* Hash table handled by BFD.  */
 443   struct bfd_link_hash_table *hash;
 444
 445   /* Hash table of symbols to keep.  This is NULL unless strip is
 446      strip_some.  */
 447   struct bfd_hash_table *keep_hash;
 448
 449   /* Hash table of symbols to report back via the notice callback.  If
 450      this is NULL, and notice_all is FALSE, then no symbols are
 451      reported back.  */
 452   struct bfd_hash_table *notice_hash;
 453
 454   /* Hash table of symbols which are being wrapped (the --wrap linker
 455      option).  If this is NULL, no symbols are being wrapped.  */
 456   struct bfd_hash_table *wrap_hash;
 457
 458   /* Hash table of symbols which may be left unresolved during
 459      a link.  If this is NULL, no symbols can be left unresolved.  */
 460   struct bfd_hash_table *ignore_hash;
 461
 462   /* The output BFD.  */
 463   bfd *output_bfd;
 464
 465   /* The list of input BFD's involved in the link.  These are chained
 466      together via the link_next field.  */
 467   bfd *input_bfds;
 468   bfd **input_bfds_tail;
 469
 470   /* If a symbol should be created for each input BFD, this is section
 471      where those symbols should be placed.  It must be a section in
 472      the output BFD.  It may be NULL, in which case no such symbols
 473      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 474      linker command language.  */
 475   asection *create_object_symbols_section;
 476
 477   /* List of global symbol names that are starting points for marking
 478      sections against garbage collection.  */
 479   struct bfd_sym_chain *gc_sym_list;
 480
 481   /* If a base output file is wanted, then this points to it */
 482   void *base_file;
 483
 484   /* The function to call when the executable or shared object is
 485      loaded.  */
 486   const char *init_function;
 487
 488   /* The function to call when the executable or shared object is
 489      unloaded.  */
 490   const char *fini_function;
 491
 492   /* Number of relaxation passes.  Usually only one relaxation pass
 493      is needed.  But a backend can have as many relaxation passes as
 494      necessary.  During bfd_relax_section call, it is set to the
 495      current pass, starting from 0.  */
 496   int relax_pass;
 497
 498   /* Number of relaxation trips.  This number is incremented every
 499      time the relaxation pass is restarted due to a previous
 500      relaxation returning true in *AGAIN.  */
 501   int relax_trip;
 502
 503   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 504      should be generated/linked against.  Set to 1 if this feature
 505      is explicitly requested by the user, -1 if enabled by default.  */
 506   int pei386_auto_import;
 507
 508   /* Non-zero if runtime relocs for DATA items with non-zero addends
 509      in pei386 DLLs should be generated.  Set to 1 if this feature
 510      is explicitly requested by the user, -1 if enabled by default.  */
 511   int pei386_runtime_pseudo_reloc;
 512
 513   /* How many spare .dynamic DT_NULL entries should be added?  */
 514   unsigned int spare_dynamic_tags;
 515
 516   /* May be used to set DT_FLAGS for ELF. */
 517   bfd_vma flags;
 518
 519   /* May be used to set DT_FLAGS_1 for ELF. */
 520   bfd_vma flags_1;
 521
 522   /* Start and end of RELRO region.  */
 523   bfd_vma relro_start, relro_end;
 524
 525   /* List of symbols should be dynamic.  */
 526   struct bfd_elf_dynamic_list *dynamic_list;
 527
 528   /* The version information.  */
 529   struct bfd_elf_version_tree *version_info;
 530 };
 531
 532 /* This structures holds a set of callback functions.  These are called
 533    by the BFD linker routines.  Except for the info functions, the first
 534    argument to each callback function is the bfd_link_info structure
 535    being used and each function returns a boolean value.  If the
 536    function returns FALSE, then the BFD function which called it should
 537    return with a failure indication.  */
 538
 539 struct bfd_link_callbacks
 540 {
 541   /* A function which is called when an object is added from an
 542      archive.  ABFD is the archive element being added.  NAME is the
 543      name of the symbol which caused the archive element to be pulled
 544      in.  This function may set *SUBSBFD to point to an alternative
 545      BFD from which symbols should in fact be added in place of the
 546      original BFD's symbols.  */
 547   bfd_boolean (*add_archive_element)
 548     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 549   /* A function which is called when a symbol is found with multiple
 550      definitions.  H is the symbol which is defined multiple times.
 551      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 552      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 553   bfd_boolean (*multiple_definition)
 554     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 555      bfd *nbfd, asection *nsec, bfd_vma nval);
 556   /* A function which is called when a common symbol is defined
 557      multiple times.  H is the symbol appearing multiple times.
 558      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 559      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 560      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 561      is the size of the new symbol.  */
 562   bfd_boolean (*multiple_common)
 563     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 564      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 565   /* A function which is called to add a symbol to a set.  ENTRY is
 566      the link hash table entry for the set itself (e.g.,
 567      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 568      the set when generating a relocatable file, and is also used to
 569      get the size of the entry when generating an executable file.
 570      ABFD, SEC and VALUE identify the value to add to the set.  */
 571   bfd_boolean (*add_to_set)
 572     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 573      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 574   /* A function which is called when the name of a g++ constructor or
 575      destructor is found.  This is only called by some object file
 576      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 577      destructor.  This will use BFD_RELOC_CTOR when generating a
 578      relocatable file.  NAME is the name of the symbol found.  ABFD,
 579      SECTION and VALUE are the value of the symbol.  */
 580   bfd_boolean (*constructor)
 581     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 582      bfd *abfd, asection *sec, bfd_vma value);
 583   /* A function which is called to issue a linker warning.  For
 584      example, this is called when there is a reference to a warning
 585      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 586      of the symbol which triggered the warning; it may be NULL if
 587      there is none.  ABFD, SECTION and ADDRESS identify the location
 588      which trigerred the warning; either ABFD or SECTION or both may
 589      be NULL if the location is not known.  */
 590   bfd_boolean (*warning)
 591     (struct bfd_link_info *, const char *warning, const char *symbol,
 592      bfd *abfd, asection *section, bfd_vma address);
 593   /* A function which is called when a relocation is attempted against
 594      an undefined symbol.  NAME is the symbol which is undefined.
 595      ABFD, SECTION and ADDRESS identify the location from which the
 596      reference is made. IS_FATAL indicates whether an undefined symbol is
 597      a fatal error or not. In some cases SECTION may be NULL.  */
 598   bfd_boolean (*undefined_symbol)
 599     (struct bfd_link_info *, const char *name, bfd *abfd,
 600      asection *section, bfd_vma address, bfd_boolean is_fatal);
 601   /* A function which is called when a reloc overflow occurs. ENTRY is
 602      the link hash table entry for the symbol the reloc is against.
 603      NAME is the name of the local symbol or section the reloc is
 604      against, RELOC_NAME is the name of the relocation, and ADDEND is
 605      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 606      location at which the overflow occurs; if this is the result of a
 607      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 608      ABFD will be NULL.  */
 609   bfd_boolean (*reloc_overflow)
 610     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 611      const char *name, const char *reloc_name, bfd_vma addend,
 612      bfd *abfd, asection *section, bfd_vma address);
 613   /* A function which is called when a dangerous reloc is performed.
 614      MESSAGE is an appropriate message.
 615      ABFD, SECTION and ADDRESS identify the location at which the
 616      problem occurred; if this is the result of a
 617      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 618      ABFD will be NULL.  */
 619   bfd_boolean (*reloc_dangerous)
 620     (struct bfd_link_info *, const char *message,
 621      bfd *abfd, asection *section, bfd_vma address);
 622   /* A function which is called when a reloc is found to be attached
 623      to a symbol which is not being written out.  NAME is the name of
 624      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 625      the reloc; if this is the result of a
 626      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 627      ABFD will be NULL.  */
 628   bfd_boolean (*unattached_reloc)
 629     (struct bfd_link_info *, const char *name,
 630      bfd *abfd, asection *section, bfd_vma address);
 631   /* A function which is called when a symbol in notice_hash is
 632      defined or referenced.  H is the symbol.  ABFD, SECTION and
 633      ADDRESS are the (new) value of the symbol.  If SECTION is
 634      bfd_und_section, this is a reference.  FLAGS are the symbol
 635      BSF_* flags.  STRING is the name of the symbol to indirect to if
 636      the sym is indirect, or the warning string if a warning sym.  */
 637   bfd_boolean (*notice)
 638     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 639      bfd *abfd, asection *section, bfd_vma address, flagword flags,
 640      const char *string);
 641   /* Error or warning link info message.  */
 642   void (*einfo)
 643     (const char *fmt, ...);
 644   /* General link info message.  */
 645   void (*info)
 646     (const char *fmt, ...);
 647   /* Message to be printed in linker map file.  */
 648   void (*minfo)
 649     (const char *fmt, ...);
 650   /* This callback provides a chance for users of the BFD library to
 651      override its decision about whether to place two adjacent sections
 652      into the same segment.  */
 653   bfd_boolean (*override_segment_assignment)
 654     (struct bfd_link_info *, bfd * abfd,
 655      asection * current_section, asection * previous_section,
 656      bfd_boolean new_segment);
 657 };
 658 \f
 659 /* The linker builds link_order structures which tell the code how to
 660    include input data in the output file.  */
 661
 662 /* These are the types of link_order structures.  */
 663
 664 enum bfd_link_order_type
 665 {
 666   bfd_undefined_link_order,     /* Undefined.  */
 667   bfd_indirect_link_order,      /* Built from a section.  */
 668   bfd_data_link_order,          /* Set to explicit data.  */
 669   bfd_section_reloc_link_order, /* Relocate against a section.  */
 670   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 671 };
 672
 673 /* This is the link_order structure itself.  These form a chain
 674    attached to the output section whose contents they are describing.  */
 675
 676 struct bfd_link_order
 677 {
 678   /* Next link_order in chain.  */
 679   struct bfd_link_order *next;
 680   /* Type of link_order.  */
 681   enum bfd_link_order_type type;
 682   /* Offset within output section.  */
 683   bfd_vma offset;
 684   /* Size within output section.  */
 685   bfd_size_type size;
 686   /* Type specific information.  */
 687   union
 688     {
 689       struct
 690         {
 691           /* Section to include.  If this is used, then
 692              section->output_section must be the section the
 693              link_order is attached to, section->output_offset must
 694              equal the link_order offset field, and section->size
 695              must equal the link_order size field.  Maybe these
 696              restrictions should be relaxed someday.  */
 697           asection *section;
 698         } indirect;
 699       struct
 700         {
 701           /* Size of contents, or zero when contents should be filled by
 702              the architecture-dependent fill function.
 703              A non-zero value allows filling of the output section
 704              with an arbitrary repeated pattern.  */
 705           unsigned int size;
 706           /* Data to put into file.  */
 707           bfd_byte *contents;
 708         } data;
 709       struct
 710         {
 711           /* Description of reloc to generate.  Used for
 712              bfd_section_reloc_link_order and
 713              bfd_symbol_reloc_link_order.  */
 714           struct bfd_link_order_reloc *p;
 715         } reloc;
 716     } u;
 717 };
 718
 719 /* A linker order of type bfd_section_reloc_link_order or
 720    bfd_symbol_reloc_link_order means to create a reloc against a
 721    section or symbol, respectively.  This is used to implement -Ur to
 722    generate relocs for the constructor tables.  The
 723    bfd_link_order_reloc structure describes the reloc that BFD should
 724    create.  It is similar to a arelent, but I didn't use arelent
 725    because the linker does not know anything about most symbols, and
 726    any asymbol structure it creates will be partially meaningless.
 727    This information could logically be in the bfd_link_order struct,
 728    but I didn't want to waste the space since these types of relocs
 729    are relatively rare.  */
 730
 731 struct bfd_link_order_reloc
 732 {
 733   /* Reloc type.  */
 734   bfd_reloc_code_real_type reloc;
 735
 736   union
 737     {
 738       /* For type bfd_section_reloc_link_order, this is the section
 739          the reloc should be against.  This must be a section in the
 740          output BFD, not any of the input BFDs.  */
 741       asection *section;
 742       /* For type bfd_symbol_reloc_link_order, this is the name of the
 743          symbol the reloc should be against.  */
 744       const char *name;
 745     } u;
 746
 747   /* Addend to use.  The object file should contain zero.  The BFD
 748      backend is responsible for filling in the contents of the object
 749      file correctly.  For some object file formats (e.g., COFF) the
 750      addend must be stored into in the object file, and for some
 751      (e.g., SPARC a.out) it is kept in the reloc.  */
 752   bfd_vma addend;
 753 };
 754
 755 /* Allocate a new link_order for a section.  */
 756 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 757
 758 /* These structures are used to describe version information for the
 759    ELF linker.  These structures could be manipulated entirely inside
 760    BFD, but it would be a pain.  Instead, the regular linker sets up
 761    these structures, and then passes them into BFD.  */
 762
 763 /* Glob pattern for a version.  */
 764
 765 struct bfd_elf_version_expr
 766 {
 767   /* Next glob pattern for this version.  */
 768   struct bfd_elf_version_expr *next;
 769   /* Glob pattern.  */
 770   const char *pattern;
 771   /* Set if pattern is not a glob.  */
 772   unsigned int literal : 1;
 773   /* Defined by ".symver".  */
 774   unsigned int symver : 1;
 775   /* Defined by version script.  */
 776   unsigned int script : 1;
 777   /* Pattern type.  */
 778 #define BFD_ELF_VERSION_C_TYPE          1
 779 #define BFD_ELF_VERSION_CXX_TYPE        2
 780 #define BFD_ELF_VERSION_JAVA_TYPE       4
 781   unsigned int mask : 3;
 782 };
 783
 784 struct bfd_elf_version_expr_head
 785 {
 786   /* List of all patterns, both wildcards and non-wildcards.  */
 787   struct bfd_elf_version_expr *list;
 788   /* Hash table for non-wildcards.  */
 789   void *htab;
 790   /* Remaining patterns.  */
 791   struct bfd_elf_version_expr *remaining;
 792   /* What kind of pattern types are present in list (bitmask).  */
 793   unsigned int mask;
 794 };
 795
 796 /* Version dependencies.  */
 797
 798 struct bfd_elf_version_deps
 799 {
 800   /* Next dependency for this version.  */
 801   struct bfd_elf_version_deps *next;
 802   /* The version which this version depends upon.  */
 803   struct bfd_elf_version_tree *version_needed;
 804 };
 805
 806 /* A node in the version tree.  */
 807
 808 struct bfd_elf_version_tree
 809 {
 810   /* Next version.  */
 811   struct bfd_elf_version_tree *next;
 812   /* Name of this version.  */
 813   const char *name;
 814   /* Version number.  */
 815   unsigned int vernum;
 816   /* Regular expressions for global symbols in this version.  */
 817   struct bfd_elf_version_expr_head globals;
 818   /* Regular expressions for local symbols in this version.  */
 819   struct bfd_elf_version_expr_head locals;
 820   /* List of versions which this version depends upon.  */
 821   struct bfd_elf_version_deps *deps;
 822   /* Index of the version name.  This is used within BFD.  */
 823   unsigned int name_indx;
 824   /* Whether this version tree was used.  This is used within BFD.  */
 825   int used;
 826   /* Matching hook.  */
 827   struct bfd_elf_version_expr *(*match)
 828     (struct bfd_elf_version_expr_head *head,
 829      struct bfd_elf_version_expr *prev, const char *sym);
 830 };
 831
 832 struct bfd_elf_dynamic_list
 833 {
 834   struct bfd_elf_version_expr_head head;
 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 #endif