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 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 190    and the remainder is found in wrap_hash, return the real symbol.  */
 191
 192 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 193   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 194
 195 /* Traverse a link hash table.  */
 196 extern void bfd_link_hash_traverse
 197   (struct bfd_link_hash_table *,
 198     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 199     void *);
 200
 201 /* Add an entry to the undefs list.  */
 202 extern void bfd_link_add_undef
 203   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 204
 205 /* Remove symbols from the undefs list that don't belong there.  */
 206 extern void bfd_link_repair_undef_list
 207   (struct bfd_link_hash_table *table);
 208
 209 /* Read symbols and cache symbol pointer array in outsymbols.  */
 210 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 211
 212 struct bfd_sym_chain
 213 {
 214   struct bfd_sym_chain *next;
 215   const char *name;
 216 };
 217 \f
 218 /* How to handle unresolved symbols.
 219    There are four possibilities which are enumerated below:  */
 220 enum report_method
 221 {
 222   /* This is the initial value when then link_info structure is created.
 223      It allows the various stages of the linker to determine whether they
 224      allowed to set the value.  */
 225   RM_NOT_YET_SET = 0,
 226   RM_IGNORE,
 227   RM_GENERATE_WARNING,
 228   RM_GENERATE_ERROR
 229 };
 230
 231 typedef enum {with_flags, without_flags} flag_type;
 232
 233 /* A section flag list.  */
 234 struct flag_info_list
 235 {
 236   flag_type with;
 237   const char *name;
 238   bfd_boolean valid;
 239   struct flag_info_list *next;
 240 };
 241
 242 /* Section flag info.  */
 243 struct flag_info
 244 {
 245   flagword only_with_flags;
 246   flagword not_with_flags;
 247   struct flag_info_list *flag_list;
 248   bfd_boolean flags_initialized;
 249 };
 250
 251 struct bfd_elf_dynamic_list;
 252 struct bfd_elf_version_tree;
 253
 254 /* This structure holds all the information needed to communicate
 255    between BFD and the linker when doing a link.  */
 256
 257 struct bfd_link_info
 258 {
 259   /* TRUE if BFD should generate a shared object (or a pie).  */
 260   unsigned int shared: 1;
 261
 262   /* TRUE if generating an executable, position independent or not.  */
 263   unsigned int executable : 1;
 264
 265   /* TRUE if generating a position independent executable.  */
 266   unsigned int pie: 1;
 267
 268   /* TRUE if BFD should generate a relocatable object file.  */
 269   unsigned int relocatable: 1;
 270
 271   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 272   unsigned int symbolic: 1;
 273
 274   /* TRUE if executable should not contain copy relocs.
 275      Setting this true may result in a non-sharable text segment.  */
 276   unsigned int nocopyreloc: 1;
 277
 278   /* TRUE if BFD should export all symbols in the dynamic symbol table
 279      of an executable, rather than only those used.  */
 280   unsigned int export_dynamic: 1;
 281
 282   /* TRUE if a default symbol version should be created and used for
 283      exported symbols.  */
 284   unsigned int create_default_symver: 1;
 285
 286   /* TRUE if unreferenced sections should be removed.  */
 287   unsigned int gc_sections: 1;
 288
 289   /* TRUE if every symbol should be reported back via the notice
 290      callback.  */
 291   unsigned int notice_all: 1;
 292
 293   /* TRUE if we are loading LTO outputs.  */
 294   unsigned int loading_lto_outputs: 1;
 295
 296   /* TRUE if global symbols in discarded sections should be stripped.  */
 297   unsigned int strip_discarded: 1;
 298
 299   /* TRUE if all data symbols should be dynamic.  */
 300   unsigned int dynamic_data: 1;
 301
 302   /* Which symbols to strip.  */
 303   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 304
 305   /* Which local symbols to discard.  */
 306   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 307
 308   /* Criteria for skipping symbols when determining
 309      whether to include an object from an archive. */
 310   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 311
 312   /* What to do with unresolved symbols in an object file.
 313      When producing executables the default is GENERATE_ERROR.
 314      When producing shared libraries the default is IGNORE.  The
 315      assumption with shared libraries is that the reference will be
 316      resolved at load/execution time.  */
 317   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 318
 319   /* What to do with unresolved symbols in a shared library.
 320      The same defaults apply.  */
 321   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 322
 323   /* TRUE if shared objects should be linked directly, not shared.  */
 324   unsigned int static_link: 1;
 325
 326   /* TRUE if symbols should be retained in memory, FALSE if they
 327      should be freed and reread.  */
 328   unsigned int keep_memory: 1;
 329
 330   /* TRUE if BFD should generate relocation information in the final
 331      executable.  */
 332   unsigned int emitrelocations: 1;
 333
 334   /* TRUE if PT_GNU_RELRO segment should be created.  */
 335   unsigned int relro: 1;
 336
 337   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 338      should be created.  */
 339   unsigned int eh_frame_hdr: 1;
 340
 341   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 342   unsigned int warn_shared_textrel: 1;
 343
 344   /* TRUE if we should error when adding a DT_TEXTREL.  */
 345   unsigned int error_textrel: 1;
 346
 347   /* TRUE if .hash section should be created.  */
 348   unsigned int emit_hash: 1;
 349
 350   /* TRUE if .gnu.hash section should be created.  */
 351   unsigned int emit_gnu_hash: 1;
 352
 353   /* If TRUE reduce memory overheads, at the expense of speed. This will
 354      cause map file generation to use an O(N^2) algorithm and disable
 355      caching ELF symbol buffer.  */
 356   unsigned int reduce_memory_overheads: 1;
 357
 358   /* TRUE if the output file should be in a traditional format.  This
 359      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 360      on the output file, but may be checked when reading the input
 361      files.  */
 362   unsigned int traditional_format: 1;
 363
 364   /* TRUE if non-PLT relocs should be merged into one reloc section
 365      and sorted so that relocs against the same symbol come together.  */
 366   unsigned int combreloc: 1;
 367
 368   /* TRUE if a default symbol version should be created and used for
 369      imported symbols.  */
 370   unsigned int default_imported_symver: 1;
 371
 372   /* TRUE if the new ELF dynamic tags are enabled. */
 373   unsigned int new_dtags: 1;
 374
 375   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 376      linker created sections, TRUE if it should be omitted.  */
 377   unsigned int no_ld_generated_unwind_info: 1;
 378
 379   /* TRUE if BFD should generate a "task linked" object file,
 380      similar to relocatable but also with globals converted to
 381      statics.  */
 382   unsigned int task_link: 1;
 383
 384   /* TRUE if ok to have multiple definition.  */
 385   unsigned int allow_multiple_definition: 1;
 386
 387   /* TRUE if ok to have version with no definition.  */
 388   unsigned int allow_undefined_version: 1;
 389
 390   /* TRUE if some symbols have to be dynamic, controlled by
 391      --dynamic-list command line options.  */
 392   unsigned int dynamic: 1;
 393
 394   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 395      flags.  */
 396   unsigned int execstack: 1;
 397
 398   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 399      flags.  */
 400   unsigned int noexecstack: 1;
 401
 402   /* TRUE if we want to produced optimized output files.  This might
 403      need much more time and therefore must be explicitly selected.  */
 404   unsigned int optimize: 1;
 405
 406   /* TRUE if user should be informed of removed unreferenced sections.  */
 407   unsigned int print_gc_sections: 1;
 408
 409   /* TRUE if we should warn alternate ELF machine code.  */
 410   unsigned int warn_alternate_em: 1;
 411
 412   /* TRUE if the linker script contained an explicit PHDRS command.  */
 413   unsigned int user_phdrs: 1;
 414
 415   /* Char that may appear as the first char of a symbol, but should be
 416      skipped (like symbol_leading_char) when looking up symbols in
 417      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 418   char wrap_char;
 419
 420   /* Separator between archive and filename in linker script filespecs.  */
 421   char path_separator;
 422
 423   /* Default stack size.  Zero means default (often zero itself), -1
 424      means explicitly zero-sized.  */
 425   bfd_signed_vma stacksize;
 426
 427   /* Enable or disable target specific optimizations.
 428
 429      Not all targets have optimizations to enable.
 430
 431      Normally these optimizations are disabled by default but some targets
 432      prefer to enable them by default.  So this field is a tri-state variable.
 433      The values are:
 434
 435      zero: Enable the optimizations (either from --relax being specified on
 436        the command line or the backend's before_allocation emulation function.
 437
 438      positive: The user has requested that these optimizations be disabled.
 439        (Via the --no-relax command line option).
 440
 441      negative: The optimizations are disabled.  (Set when initializing the
 442        args_type structure in ldmain.c:main.  */
 443   signed int disable_target_specific_optimizations;
 444
 445   /* Function callbacks.  */
 446   const struct bfd_link_callbacks *callbacks;
 447
 448   /* Hash table handled by BFD.  */
 449   struct bfd_link_hash_table *hash;
 450
 451   /* Hash table of symbols to keep.  This is NULL unless strip is
 452      strip_some.  */
 453   struct bfd_hash_table *keep_hash;
 454
 455   /* Hash table of symbols to report back via the notice callback.  If
 456      this is NULL, and notice_all is FALSE, then no symbols are
 457      reported back.  */
 458   struct bfd_hash_table *notice_hash;
 459
 460   /* Hash table of symbols which are being wrapped (the --wrap linker
 461      option).  If this is NULL, no symbols are being wrapped.  */
 462   struct bfd_hash_table *wrap_hash;
 463
 464   /* Hash table of symbols which may be left unresolved during
 465      a link.  If this is NULL, no symbols can be left unresolved.  */
 466   struct bfd_hash_table *ignore_hash;
 467
 468   /* The output BFD.  */
 469   bfd *output_bfd;
 470
 471   /* The list of input BFD's involved in the link.  These are chained
 472      together via the link_next field.  */
 473   bfd *input_bfds;
 474   bfd **input_bfds_tail;
 475
 476   /* If a symbol should be created for each input BFD, this is section
 477      where those symbols should be placed.  It must be a section in
 478      the output BFD.  It may be NULL, in which case no such symbols
 479      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 480      linker command language.  */
 481   asection *create_object_symbols_section;
 482
 483   /* List of global symbol names that are starting points for marking
 484      sections against garbage collection.  */
 485   struct bfd_sym_chain *gc_sym_list;
 486
 487   /* If a base output file is wanted, then this points to it */
 488   void *base_file;
 489
 490   /* The function to call when the executable or shared object is
 491      loaded.  */
 492   const char *init_function;
 493
 494   /* The function to call when the executable or shared object is
 495      unloaded.  */
 496   const char *fini_function;
 497
 498   /* Number of relaxation passes.  Usually only one relaxation pass
 499      is needed.  But a backend can have as many relaxation passes as
 500      necessary.  During bfd_relax_section call, it is set to the
 501      current pass, starting from 0.  */
 502   int relax_pass;
 503
 504   /* Number of relaxation trips.  This number is incremented every
 505      time the relaxation pass is restarted due to a previous
 506      relaxation returning true in *AGAIN.  */
 507   int relax_trip;
 508
 509   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 510      should be generated/linked against.  Set to 1 if this feature
 511      is explicitly requested by the user, -1 if enabled by default.  */
 512   int pei386_auto_import;
 513
 514   /* Non-zero if runtime relocs for DATA items with non-zero addends
 515      in pei386 DLLs should be generated.  Set to 1 if this feature
 516      is explicitly requested by the user, -1 if enabled by default.  */
 517   int pei386_runtime_pseudo_reloc;
 518
 519   /* How many spare .dynamic DT_NULL entries should be added?  */
 520   unsigned int spare_dynamic_tags;
 521
 522   /* May be used to set DT_FLAGS for ELF. */
 523   bfd_vma flags;
 524
 525   /* May be used to set DT_FLAGS_1 for ELF. */
 526   bfd_vma flags_1;
 527
 528   /* Start and end of RELRO region.  */
 529   bfd_vma relro_start, relro_end;
 530
 531   /* List of symbols should be dynamic.  */
 532   struct bfd_elf_dynamic_list *dynamic_list;
 533
 534   /* The version information.  */
 535   struct bfd_elf_version_tree *version_info;
 536 };
 537
 538 /* This structures holds a set of callback functions.  These are called
 539    by the BFD linker routines.  Except for the info functions, the first
 540    argument to each callback function is the bfd_link_info structure
 541    being used and each function returns a boolean value.  If the
 542    function returns FALSE, then the BFD function which called it should
 543    return with a failure indication.  */
 544
 545 struct bfd_link_callbacks
 546 {
 547   /* A function which is called when an object is added from an
 548      archive.  ABFD is the archive element being added.  NAME is the
 549      name of the symbol which caused the archive element to be pulled
 550      in.  This function may set *SUBSBFD to point to an alternative
 551      BFD from which symbols should in fact be added in place of the
 552      original BFD's symbols.  */
 553   bfd_boolean (*add_archive_element)
 554     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 555   /* A function which is called when a symbol is found with multiple
 556      definitions.  H is the symbol which is defined multiple times.
 557      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 558      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 559   bfd_boolean (*multiple_definition)
 560     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 561      bfd *nbfd, asection *nsec, bfd_vma nval);
 562   /* A function which is called when a common symbol is defined
 563      multiple times.  H is the symbol appearing multiple times.
 564      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 565      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 566      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 567      is the size of the new symbol.  */
 568   bfd_boolean (*multiple_common)
 569     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 570      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 571   /* A function which is called to add a symbol to a set.  ENTRY is
 572      the link hash table entry for the set itself (e.g.,
 573      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 574      the set when generating a relocatable file, and is also used to
 575      get the size of the entry when generating an executable file.
 576      ABFD, SEC and VALUE identify the value to add to the set.  */
 577   bfd_boolean (*add_to_set)
 578     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 579      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 580   /* A function which is called when the name of a g++ constructor or
 581      destructor is found.  This is only called by some object file
 582      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 583      destructor.  This will use BFD_RELOC_CTOR when generating a
 584      relocatable file.  NAME is the name of the symbol found.  ABFD,
 585      SECTION and VALUE are the value of the symbol.  */
 586   bfd_boolean (*constructor)
 587     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 588      bfd *abfd, asection *sec, bfd_vma value);
 589   /* A function which is called to issue a linker warning.  For
 590      example, this is called when there is a reference to a warning
 591      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 592      of the symbol which triggered the warning; it may be NULL if
 593      there is none.  ABFD, SECTION and ADDRESS identify the location
 594      which trigerred the warning; either ABFD or SECTION or both may
 595      be NULL if the location is not known.  */
 596   bfd_boolean (*warning)
 597     (struct bfd_link_info *, const char *warning, const char *symbol,
 598      bfd *abfd, asection *section, bfd_vma address);
 599   /* A function which is called when a relocation is attempted against
 600      an undefined symbol.  NAME is the symbol which is undefined.
 601      ABFD, SECTION and ADDRESS identify the location from which the
 602      reference is made. IS_FATAL indicates whether an undefined symbol is
 603      a fatal error or not. In some cases SECTION may be NULL.  */
 604   bfd_boolean (*undefined_symbol)
 605     (struct bfd_link_info *, const char *name, bfd *abfd,
 606      asection *section, bfd_vma address, bfd_boolean is_fatal);
 607   /* A function which is called when a reloc overflow occurs. ENTRY is
 608      the link hash table entry for the symbol the reloc is against.
 609      NAME is the name of the local symbol or section the reloc is
 610      against, RELOC_NAME is the name of the relocation, and ADDEND is
 611      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 612      location at which the overflow occurs; if this is the result of a
 613      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 614      ABFD will be NULL.  */
 615   bfd_boolean (*reloc_overflow)
 616     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 617      const char *name, const char *reloc_name, bfd_vma addend,
 618      bfd *abfd, asection *section, bfd_vma address);
 619   /* A function which is called when a dangerous reloc is performed.
 620      MESSAGE is an appropriate message.
 621      ABFD, SECTION and ADDRESS identify the location at which the
 622      problem occurred; if this is the result of a
 623      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 624      ABFD will be NULL.  */
 625   bfd_boolean (*reloc_dangerous)
 626     (struct bfd_link_info *, const char *message,
 627      bfd *abfd, asection *section, bfd_vma address);
 628   /* A function which is called when a reloc is found to be attached
 629      to a symbol which is not being written out.  NAME is the name of
 630      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 631      the reloc; if this is the result of a
 632      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 633      ABFD will be NULL.  */
 634   bfd_boolean (*unattached_reloc)
 635     (struct bfd_link_info *, const char *name,
 636      bfd *abfd, asection *section, bfd_vma address);
 637   /* A function which is called when a symbol in notice_hash is
 638      defined or referenced.  H is the symbol.  ABFD, SECTION and
 639      ADDRESS are the (new) value of the symbol.  If SECTION is
 640      bfd_und_section, this is a reference.  FLAGS are the symbol
 641      BSF_* flags.  STRING is the name of the symbol to indirect to if
 642      the sym is indirect, or the warning string if a warning sym.  */
 643   bfd_boolean (*notice)
 644     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 645      bfd *abfd, asection *section, bfd_vma address, flagword flags,
 646      const char *string);
 647   /* Error or warning link info message.  */
 648   void (*einfo)
 649     (const char *fmt, ...);
 650   /* General link info message.  */
 651   void (*info)
 652     (const char *fmt, ...);
 653   /* Message to be printed in linker map file.  */
 654   void (*minfo)
 655     (const char *fmt, ...);
 656   /* This callback provides a chance for users of the BFD library to
 657      override its decision about whether to place two adjacent sections
 658      into the same segment.  */
 659   bfd_boolean (*override_segment_assignment)
 660     (struct bfd_link_info *, bfd * abfd,
 661      asection * current_section, asection * previous_section,
 662      bfd_boolean new_segment);
 663 };
 664 \f
 665 /* The linker builds link_order structures which tell the code how to
 666    include input data in the output file.  */
 667
 668 /* These are the types of link_order structures.  */
 669
 670 enum bfd_link_order_type
 671 {
 672   bfd_undefined_link_order,     /* Undefined.  */
 673   bfd_indirect_link_order,      /* Built from a section.  */
 674   bfd_data_link_order,          /* Set to explicit data.  */
 675   bfd_section_reloc_link_order, /* Relocate against a section.  */
 676   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 677 };
 678
 679 /* This is the link_order structure itself.  These form a chain
 680    attached to the output section whose contents they are describing.  */
 681
 682 struct bfd_link_order
 683 {
 684   /* Next link_order in chain.  */
 685   struct bfd_link_order *next;
 686   /* Type of link_order.  */
 687   enum bfd_link_order_type type;
 688   /* Offset within output section.  */
 689   bfd_vma offset;
 690   /* Size within output section.  */
 691   bfd_size_type size;
 692   /* Type specific information.  */
 693   union
 694     {
 695       struct
 696         {
 697           /* Section to include.  If this is used, then
 698              section->output_section must be the section the
 699              link_order is attached to, section->output_offset must
 700              equal the link_order offset field, and section->size
 701              must equal the link_order size field.  Maybe these
 702              restrictions should be relaxed someday.  */
 703           asection *section;
 704         } indirect;
 705       struct
 706         {
 707           /* Size of contents, or zero when contents should be filled by
 708              the architecture-dependent fill function.
 709              A non-zero value allows filling of the output section
 710              with an arbitrary repeated pattern.  */
 711           unsigned int size;
 712           /* Data to put into file.  */
 713           bfd_byte *contents;
 714         } data;
 715       struct
 716         {
 717           /* Description of reloc to generate.  Used for
 718              bfd_section_reloc_link_order and
 719              bfd_symbol_reloc_link_order.  */
 720           struct bfd_link_order_reloc *p;
 721         } reloc;
 722     } u;
 723 };
 724
 725 /* A linker order of type bfd_section_reloc_link_order or
 726    bfd_symbol_reloc_link_order means to create a reloc against a
 727    section or symbol, respectively.  This is used to implement -Ur to
 728    generate relocs for the constructor tables.  The
 729    bfd_link_order_reloc structure describes the reloc that BFD should
 730    create.  It is similar to a arelent, but I didn't use arelent
 731    because the linker does not know anything about most symbols, and
 732    any asymbol structure it creates will be partially meaningless.
 733    This information could logically be in the bfd_link_order struct,
 734    but I didn't want to waste the space since these types of relocs
 735    are relatively rare.  */
 736
 737 struct bfd_link_order_reloc
 738 {
 739   /* Reloc type.  */
 740   bfd_reloc_code_real_type reloc;
 741
 742   union
 743     {
 744       /* For type bfd_section_reloc_link_order, this is the section
 745          the reloc should be against.  This must be a section in the
 746          output BFD, not any of the input BFDs.  */
 747       asection *section;
 748       /* For type bfd_symbol_reloc_link_order, this is the name of the
 749          symbol the reloc should be against.  */
 750       const char *name;
 751     } u;
 752
 753   /* Addend to use.  The object file should contain zero.  The BFD
 754      backend is responsible for filling in the contents of the object
 755      file correctly.  For some object file formats (e.g., COFF) the
 756      addend must be stored into in the object file, and for some
 757      (e.g., SPARC a.out) it is kept in the reloc.  */
 758   bfd_vma addend;
 759 };
 760
 761 /* Allocate a new link_order for a section.  */
 762 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 763
 764 /* These structures are used to describe version information for the
 765    ELF linker.  These structures could be manipulated entirely inside
 766    BFD, but it would be a pain.  Instead, the regular linker sets up
 767    these structures, and then passes them into BFD.  */
 768
 769 /* Glob pattern for a version.  */
 770
 771 struct bfd_elf_version_expr
 772 {
 773   /* Next glob pattern for this version.  */
 774   struct bfd_elf_version_expr *next;
 775   /* Glob pattern.  */
 776   const char *pattern;
 777   /* Set if pattern is not a glob.  */
 778   unsigned int literal : 1;
 779   /* Defined by ".symver".  */
 780   unsigned int symver : 1;
 781   /* Defined by version script.  */
 782   unsigned int script : 1;
 783   /* Pattern type.  */
 784 #define BFD_ELF_VERSION_C_TYPE          1
 785 #define BFD_ELF_VERSION_CXX_TYPE        2
 786 #define BFD_ELF_VERSION_JAVA_TYPE       4
 787   unsigned int mask : 3;
 788 };
 789
 790 struct bfd_elf_version_expr_head
 791 {
 792   /* List of all patterns, both wildcards and non-wildcards.  */
 793   struct bfd_elf_version_expr *list;
 794   /* Hash table for non-wildcards.  */
 795   void *htab;
 796   /* Remaining patterns.  */
 797   struct bfd_elf_version_expr *remaining;
 798   /* What kind of pattern types are present in list (bitmask).  */
 799   unsigned int mask;
 800 };
 801
 802 /* Version dependencies.  */
 803
 804 struct bfd_elf_version_deps
 805 {
 806   /* Next dependency for this version.  */
 807   struct bfd_elf_version_deps *next;
 808   /* The version which this version depends upon.  */
 809   struct bfd_elf_version_tree *version_needed;
 810 };
 811
 812 /* A node in the version tree.  */
 813
 814 struct bfd_elf_version_tree
 815 {
 816   /* Next version.  */
 817   struct bfd_elf_version_tree *next;
 818   /* Name of this version.  */
 819   const char *name;
 820   /* Version number.  */
 821   unsigned int vernum;
 822   /* Regular expressions for global symbols in this version.  */
 823   struct bfd_elf_version_expr_head globals;
 824   /* Regular expressions for local symbols in this version.  */
 825   struct bfd_elf_version_expr_head locals;
 826   /* List of versions which this version depends upon.  */
 827   struct bfd_elf_version_deps *deps;
 828   /* Index of the version name.  This is used within BFD.  */
 829   unsigned int name_indx;
 830   /* Whether this version tree was used.  This is used within BFD.  */
 831   int used;
 832   /* Matching hook.  */
 833   struct bfd_elf_version_expr *(*match)
 834     (struct bfd_elf_version_expr_head *head,
 835      struct bfd_elf_version_expr *prev, const char *sym);
 836 };
 837
 838 struct bfd_elf_dynamic_list
 839 {
 840   struct bfd_elf_version_expr_head head;
 841   struct bfd_elf_version_expr *(*match)
 842     (struct bfd_elf_version_expr_head *head,
 843      struct bfd_elf_version_expr *prev, const char *sym);
 844 };
 845
 846 #endif