include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2015 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   /* Symbol is referenced in a normal object file, as distict from a LTO
  95      IR object file.  */
  96   unsigned int non_ir_ref : 1;
  97
  98   /* Symbol is a built-in define.  These will be overridden by PROVIDE
  99      in a linker script.  */
 100   unsigned int linker_def : 1;
 101
 102   /* A union of information depending upon the type.  */
 103   union
 104     {
 105       /* Nothing is kept for bfd_hash_new.  */
 106       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 107       struct
 108         {
 109           /* Undefined and common symbols are kept in a linked list through
 110              this field.  This field is present in all of the union element
 111              so that we don't need to remove entries from the list when we
 112              change their type.  Removing entries would either require the
 113              list to be doubly linked, which would waste more memory, or
 114              require a traversal.  When an undefined or common symbol is
 115              created, it should be added to this list, the head of which is in
 116              the link hash table itself.  As symbols are defined, they need
 117              not be removed from the list; anything which reads the list must
 118              doublecheck the symbol type.
 119
 120              Weak symbols are not kept on this list.
 121
 122              Defined and defweak symbols use this field as a reference marker.
 123              If the field is not NULL, or this structure is the tail of the
 124              undefined symbol list, the symbol has been referenced.  If the
 125              symbol is undefined and becomes defined, this field will
 126              automatically be non-NULL since the symbol will have been on the
 127              undefined symbol list.  */
 128           struct bfd_link_hash_entry *next;
 129           bfd *abfd;            /* BFD symbol was found in.  */
 130         } undef;
 131       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 132       struct
 133         {
 134           struct bfd_link_hash_entry *next;
 135           asection *section;    /* Symbol section.  */
 136           bfd_vma value;        /* Symbol value.  */
 137         } def;
 138       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 139       struct
 140         {
 141           struct bfd_link_hash_entry *next;
 142           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 143           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 144         } i;
 145       /* bfd_link_hash_common.  */
 146       struct
 147         {
 148           struct bfd_link_hash_entry *next;
 149           /* The linker needs to know three things about common
 150              symbols: the size, the alignment, and the section in
 151              which the symbol should be placed.  We store the size
 152              here, and we allocate a small structure to hold the
 153              section and the alignment.  The alignment is stored as a
 154              power of two.  We don't store all the information
 155              directly because we don't want to increase the size of
 156              the union; this structure is a major space user in the
 157              linker.  */
 158           struct bfd_link_hash_common_entry *p;
 159           bfd_size_type size;   /* Common symbol size.  */
 160         } c;
 161     } u;
 162 };
 163
 164 /* This is the link hash table.  It is a derived class of
 165    bfd_hash_table.  */
 166
 167 struct bfd_link_hash_table
 168 {
 169   /* The hash table itself.  */
 170   struct bfd_hash_table table;
 171   /* A linked list of undefined and common symbols, linked through the
 172      next field in the bfd_link_hash_entry structure.  */
 173   struct bfd_link_hash_entry *undefs;
 174   /* Entries are added to the tail of the undefs list.  */
 175   struct bfd_link_hash_entry *undefs_tail;
 176   /* Function to free the hash table on closing BFD.  */
 177   void (*hash_table_free) (bfd *);
 178   /* The type of the link hash table.  */
 179   enum bfd_link_hash_table_type type;
 180 };
 181
 182 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 183    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 184    the real symbol.  */
 185 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 186   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 187    bfd_boolean copy, bfd_boolean follow);
 188
 189 /* Look up an entry in the main linker hash table if the symbol might
 190    be wrapped.  This should only be used for references to an
 191    undefined symbol, not for definitions of a symbol.  */
 192
 193 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 194   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 195    bfd_boolean, bfd_boolean);
 196
 197 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 198    and the remainder is found in wrap_hash, return the real symbol.  */
 199
 200 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 201   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 202
 203 /* Traverse a link hash table.  */
 204 extern void bfd_link_hash_traverse
 205   (struct bfd_link_hash_table *,
 206     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 207     void *);
 208
 209 /* Add an entry to the undefs list.  */
 210 extern void bfd_link_add_undef
 211   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 212
 213 /* Remove symbols from the undefs list that don't belong there.  */
 214 extern void bfd_link_repair_undef_list
 215   (struct bfd_link_hash_table *table);
 216
 217 /* Read symbols and cache symbol pointer array in outsymbols.  */
 218 extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
 219
 220 struct bfd_sym_chain
 221 {
 222   struct bfd_sym_chain *next;
 223   const char *name;
 224 };
 225 \f
 226 /* How to handle unresolved symbols.
 227    There are four possibilities which are enumerated below:  */
 228 enum report_method
 229 {
 230   /* This is the initial value when then link_info structure is created.
 231      It allows the various stages of the linker to determine whether they
 232      allowed to set the value.  */
 233   RM_NOT_YET_SET = 0,
 234   RM_IGNORE,
 235   RM_GENERATE_WARNING,
 236   RM_GENERATE_ERROR
 237 };
 238
 239 typedef enum {with_flags, without_flags} flag_type;
 240
 241 /* A section flag list.  */
 242 struct flag_info_list
 243 {
 244   flag_type with;
 245   const char *name;
 246   bfd_boolean valid;
 247   struct flag_info_list *next;
 248 };
 249
 250 /* Section flag info.  */
 251 struct flag_info
 252 {
 253   flagword only_with_flags;
 254   flagword not_with_flags;
 255   struct flag_info_list *flag_list;
 256   bfd_boolean flags_initialized;
 257 };
 258
 259 struct bfd_elf_dynamic_list;
 260 struct bfd_elf_version_tree;
 261
 262 /* Types of output.  */
 263
 264 enum output_type
 265 {
 266   type_executable = 0,
 267   type_dll,
 268   type_relocatable
 269 };
 270
 271 #define bfd_link_executable(info)  ((info)->type == type_executable)
 272 #define bfd_link_dll(info)         ((info)->type == type_dll)
 273 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 274 #define bfd_link_pic(info)         (info)->pic
 275 #define bfd_link_pie(info)         (bfd_link_executable (info) \
 276                                     && bfd_link_pic (info))
 277
 278 /* This structure holds all the information needed to communicate
 279    between BFD and the linker when doing a link.  */
 280
 281 struct bfd_link_info
 282 {
 283   /* Output type.  */
 284   ENUM_BITFIELD (output_type) type : 2;
 285
 286   /* TRUE if BFD should generate a position independent object.  */
 287   unsigned int pic : 1;
 288
 289   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 290   unsigned int symbolic: 1;
 291
 292   /* TRUE if executable should not contain copy relocs.
 293      Setting this true may result in a non-sharable text segment.  */
 294   unsigned int nocopyreloc: 1;
 295
 296   /* TRUE if BFD should export all symbols in the dynamic symbol table
 297      of an executable, rather than only those used.  */
 298   unsigned int export_dynamic: 1;
 299
 300   /* TRUE if a default symbol version should be created and used for
 301      exported symbols.  */
 302   unsigned int create_default_symver: 1;
 303
 304   /* TRUE if unreferenced sections should be removed.  */
 305   unsigned int gc_sections: 1;
 306
 307   /* TRUE if every symbol should be reported back via the notice
 308      callback.  */
 309   unsigned int notice_all: 1;
 310
 311   /* TRUE if the LTO plugin is active.  */
 312   unsigned int lto_plugin_active: 1;
 313
 314   /* TRUE if global symbols in discarded sections should be stripped.  */
 315   unsigned int strip_discarded: 1;
 316
 317   /* TRUE if all data symbols should be dynamic.  */
 318   unsigned int dynamic_data: 1;
 319
 320   /* Which symbols to strip.  */
 321   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 322
 323   /* Which local symbols to discard.  */
 324   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 325
 326   /* Criteria for skipping symbols when determining
 327      whether to include an object from an archive. */
 328   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 329
 330   /* What to do with unresolved symbols in an object file.
 331      When producing executables the default is GENERATE_ERROR.
 332      When producing shared libraries the default is IGNORE.  The
 333      assumption with shared libraries is that the reference will be
 334      resolved at load/execution time.  */
 335   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 336
 337   /* What to do with unresolved symbols in a shared library.
 338      The same defaults apply.  */
 339   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 340
 341   /* TRUE if shared objects should be linked directly, not shared.  */
 342   unsigned int static_link: 1;
 343
 344   /* TRUE if symbols should be retained in memory, FALSE if they
 345      should be freed and reread.  */
 346   unsigned int keep_memory: 1;
 347
 348   /* TRUE if BFD should generate relocation information in the final
 349      executable.  */
 350   unsigned int emitrelocations: 1;
 351
 352   /* TRUE if PT_GNU_RELRO segment should be created.  */
 353   unsigned int relro: 1;
 354
 355   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 356      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 357   unsigned int eh_frame_hdr_type: 2;
 358
 359   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 360   unsigned int warn_shared_textrel: 1;
 361
 362   /* TRUE if we should error when adding a DT_TEXTREL.  */
 363   unsigned int error_textrel: 1;
 364
 365   /* TRUE if .hash section should be created.  */
 366   unsigned int emit_hash: 1;
 367
 368   /* TRUE if .gnu.hash section should be created.  */
 369   unsigned int emit_gnu_hash: 1;
 370
 371   /* If TRUE reduce memory overheads, at the expense of speed. This will
 372      cause map file generation to use an O(N^2) algorithm and disable
 373      caching ELF symbol buffer.  */
 374   unsigned int reduce_memory_overheads: 1;
 375
 376   /* TRUE if the output file should be in a traditional format.  This
 377      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 378      on the output file, but may be checked when reading the input
 379      files.  */
 380   unsigned int traditional_format: 1;
 381
 382   /* TRUE if non-PLT relocs should be merged into one reloc section
 383      and sorted so that relocs against the same symbol come together.  */
 384   unsigned int combreloc: 1;
 385
 386   /* TRUE if a default symbol version should be created and used for
 387      imported symbols.  */
 388   unsigned int default_imported_symver: 1;
 389
 390   /* TRUE if the new ELF dynamic tags are enabled. */
 391   unsigned int new_dtags: 1;
 392
 393   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 394      linker created sections, TRUE if it should be omitted.  */
 395   unsigned int no_ld_generated_unwind_info: 1;
 396
 397   /* TRUE if BFD should generate a "task linked" object file,
 398      similar to relocatable but also with globals converted to
 399      statics.  */
 400   unsigned int task_link: 1;
 401
 402   /* TRUE if ok to have multiple definition.  */
 403   unsigned int allow_multiple_definition: 1;
 404
 405   /* TRUE if ok to have version with no definition.  */
 406   unsigned int allow_undefined_version: 1;
 407
 408   /* TRUE if some symbols have to be dynamic, controlled by
 409      --dynamic-list command line options.  */
 410   unsigned int dynamic: 1;
 411
 412   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 413      flags.  */
 414   unsigned int execstack: 1;
 415
 416   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 417      flags.  */
 418   unsigned int noexecstack: 1;
 419
 420   /* TRUE if we want to produced optimized output files.  This might
 421      need much more time and therefore must be explicitly selected.  */
 422   unsigned int optimize: 1;
 423
 424   /* TRUE if user should be informed of removed unreferenced sections.  */
 425   unsigned int print_gc_sections: 1;
 426
 427   /* TRUE if we should warn alternate ELF machine code.  */
 428   unsigned int warn_alternate_em: 1;
 429
 430   /* TRUE if the linker script contained an explicit PHDRS command.  */
 431   unsigned int user_phdrs: 1;
 432
 433   /* TRUE if BND prefix in PLT entries is always generated.  */
 434   unsigned int bndplt: 1;
 435
 436   /* Char that may appear as the first char of a symbol, but should be
 437      skipped (like symbol_leading_char) when looking up symbols in
 438      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 439   char wrap_char;
 440
 441   /* Separator between archive and filename in linker script filespecs.  */
 442   char path_separator;
 443
 444   /* Compress DWARF debug sections.  */
 445   enum compressed_debug_section_type compress_debug;
 446
 447   /* Default stack size.  Zero means default (often zero itself), -1
 448      means explicitly zero-sized.  */
 449   bfd_signed_vma stacksize;
 450
 451   /* Enable or disable target specific optimizations.
 452
 453      Not all targets have optimizations to enable.
 454
 455      Normally these optimizations are disabled by default but some targets
 456      prefer to enable them by default.  So this field is a tri-state variable.
 457      The values are:
 458
 459      zero: Enable the optimizations (either from --relax being specified on
 460        the command line or the backend's before_allocation emulation function.
 461
 462      positive: The user has requested that these optimizations be disabled.
 463        (Via the --no-relax command line option).
 464
 465      negative: The optimizations are disabled.  (Set when initializing the
 466        args_type structure in ldmain.c:main.  */
 467   signed int disable_target_specific_optimizations;
 468
 469   /* Function callbacks.  */
 470   const struct bfd_link_callbacks *callbacks;
 471
 472   /* Hash table handled by BFD.  */
 473   struct bfd_link_hash_table *hash;
 474
 475   /* Hash table of symbols to keep.  This is NULL unless strip is
 476      strip_some.  */
 477   struct bfd_hash_table *keep_hash;
 478
 479   /* Hash table of symbols to report back via the notice callback.  If
 480      this is NULL, and notice_all is FALSE, then no symbols are
 481      reported back.  */
 482   struct bfd_hash_table *notice_hash;
 483
 484   /* Hash table of symbols which are being wrapped (the --wrap linker
 485      option).  If this is NULL, no symbols are being wrapped.  */
 486   struct bfd_hash_table *wrap_hash;
 487
 488   /* Hash table of symbols which may be left unresolved during
 489      a link.  If this is NULL, no symbols can be left unresolved.  */
 490   struct bfd_hash_table *ignore_hash;
 491
 492   /* The output BFD.  */
 493   bfd *output_bfd;
 494
 495   /* The list of input BFD's involved in the link.  These are chained
 496      together via the link.next field.  */
 497   bfd *input_bfds;
 498   bfd **input_bfds_tail;
 499
 500   /* If a symbol should be created for each input BFD, this is section
 501      where those symbols should be placed.  It must be a section in
 502      the output BFD.  It may be NULL, in which case no such symbols
 503      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 504      linker command language.  */
 505   asection *create_object_symbols_section;
 506
 507   /* List of global symbol names that are starting points for marking
 508      sections against garbage collection.  */
 509   struct bfd_sym_chain *gc_sym_list;
 510
 511   /* If a base output file is wanted, then this points to it */
 512   void *base_file;
 513
 514   /* The function to call when the executable or shared object is
 515      loaded.  */
 516   const char *init_function;
 517
 518   /* The function to call when the executable or shared object is
 519      unloaded.  */
 520   const char *fini_function;
 521
 522   /* Number of relaxation passes.  Usually only one relaxation pass
 523      is needed.  But a backend can have as many relaxation passes as
 524      necessary.  During bfd_relax_section call, it is set to the
 525      current pass, starting from 0.  */
 526   int relax_pass;
 527
 528   /* Number of relaxation trips.  This number is incremented every
 529      time the relaxation pass is restarted due to a previous
 530      relaxation returning true in *AGAIN.  */
 531   int relax_trip;
 532
 533   /* > 0 to treat protected data defined in the shared library as
 534      reference external.  0 to treat it as internal.  -1 to let
 535      backend to decide.  */
 536   int extern_protected_data;
 537
 538   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 539      should be generated/linked against.  Set to 1 if this feature
 540      is explicitly requested by the user, -1 if enabled by default.  */
 541   int pei386_auto_import;
 542
 543   /* Non-zero if runtime relocs for DATA items with non-zero addends
 544      in pei386 DLLs should be generated.  Set to 1 if this feature
 545      is explicitly requested by the user, -1 if enabled by default.  */
 546   int pei386_runtime_pseudo_reloc;
 547
 548   /* How many spare .dynamic DT_NULL entries should be added?  */
 549   unsigned int spare_dynamic_tags;
 550
 551   /* May be used to set DT_FLAGS for ELF. */
 552   bfd_vma flags;
 553
 554   /* May be used to set DT_FLAGS_1 for ELF. */
 555   bfd_vma flags_1;
 556
 557   /* Start and end of RELRO region.  */
 558   bfd_vma relro_start, relro_end;
 559
 560   /* List of symbols should be dynamic.  */
 561   struct bfd_elf_dynamic_list *dynamic_list;
 562
 563   /* The version information.  */
 564   struct bfd_elf_version_tree *version_info;
 565 };
 566
 567 /* This structures holds a set of callback functions.  These are called
 568    by the BFD linker routines.  Except for the info functions, the first
 569    argument to each callback function is the bfd_link_info structure
 570    being used and each function returns a boolean value.  If the
 571    function returns FALSE, then the BFD function which called it should
 572    return with a failure indication.  */
 573
 574 struct bfd_link_callbacks
 575 {
 576   /* A function which is called when an object is added from an
 577      archive.  ABFD is the archive element being added.  NAME is the
 578      name of the symbol which caused the archive element to be pulled
 579      in.  This function may set *SUBSBFD to point to an alternative
 580      BFD from which symbols should in fact be added in place of the
 581      original BFD's symbols.  */
 582   bfd_boolean (*add_archive_element)
 583     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 584   /* A function which is called when a symbol is found with multiple
 585      definitions.  H is the symbol which is defined multiple times.
 586      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 587      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 588   bfd_boolean (*multiple_definition)
 589     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 590      bfd *nbfd, asection *nsec, bfd_vma nval);
 591   /* A function which is called when a common symbol is defined
 592      multiple times.  H is the symbol appearing multiple times.
 593      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 594      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 595      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 596      is the size of the new symbol.  */
 597   bfd_boolean (*multiple_common)
 598     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 599      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 600   /* A function which is called to add a symbol to a set.  ENTRY is
 601      the link hash table entry for the set itself (e.g.,
 602      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 603      the set when generating a relocatable file, and is also used to
 604      get the size of the entry when generating an executable file.
 605      ABFD, SEC and VALUE identify the value to add to the set.  */
 606   bfd_boolean (*add_to_set)
 607     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 608      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 609   /* A function which is called when the name of a g++ constructor or
 610      destructor is found.  This is only called by some object file
 611      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 612      destructor.  This will use BFD_RELOC_CTOR when generating a
 613      relocatable file.  NAME is the name of the symbol found.  ABFD,
 614      SECTION and VALUE are the value of the symbol.  */
 615   bfd_boolean (*constructor)
 616     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 617      bfd *abfd, asection *sec, bfd_vma value);
 618   /* A function which is called to issue a linker warning.  For
 619      example, this is called when there is a reference to a warning
 620      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 621      of the symbol which triggered the warning; it may be NULL if
 622      there is none.  ABFD, SECTION and ADDRESS identify the location
 623      which trigerred the warning; either ABFD or SECTION or both may
 624      be NULL if the location is not known.  */
 625   bfd_boolean (*warning)
 626     (struct bfd_link_info *, const char *warning, const char *symbol,
 627      bfd *abfd, asection *section, bfd_vma address);
 628   /* A function which is called when a relocation is attempted against
 629      an undefined symbol.  NAME is the symbol which is undefined.
 630      ABFD, SECTION and ADDRESS identify the location from which the
 631      reference is made. IS_FATAL indicates whether an undefined symbol is
 632      a fatal error or not. In some cases SECTION may be NULL.  */
 633   bfd_boolean (*undefined_symbol)
 634     (struct bfd_link_info *, const char *name, bfd *abfd,
 635      asection *section, bfd_vma address, bfd_boolean is_fatal);
 636   /* A function which is called when a reloc overflow occurs. ENTRY is
 637      the link hash table entry for the symbol the reloc is against.
 638      NAME is the name of the local symbol or section the reloc is
 639      against, RELOC_NAME is the name of the relocation, and ADDEND is
 640      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 641      location at which the overflow occurs; if this is the result of a
 642      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 643      ABFD will be NULL.  */
 644   bfd_boolean (*reloc_overflow)
 645     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 646      const char *name, const char *reloc_name, bfd_vma addend,
 647      bfd *abfd, asection *section, bfd_vma address);
 648   /* A function which is called when a dangerous reloc is performed.
 649      MESSAGE is an appropriate message.
 650      ABFD, SECTION and ADDRESS identify the location at which the
 651      problem occurred; if this is the result of a
 652      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 653      ABFD will be NULL.  */
 654   bfd_boolean (*reloc_dangerous)
 655     (struct bfd_link_info *, const char *message,
 656      bfd *abfd, asection *section, bfd_vma address);
 657   /* A function which is called when a reloc is found to be attached
 658      to a symbol which is not being written out.  NAME is the name of
 659      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 660      the reloc; if this is the result of a
 661      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 662      ABFD will be NULL.  */
 663   bfd_boolean (*unattached_reloc)
 664     (struct bfd_link_info *, const char *name,
 665      bfd *abfd, asection *section, bfd_vma address);
 666   /* A function which is called when a symbol in notice_hash is
 667      defined or referenced.  H is the symbol, INH the indirect symbol
 668      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 669      the symbol.  If SECTION is bfd_und_section, this is a reference.
 670      FLAGS are the symbol BSF_* flags.  */
 671   bfd_boolean (*notice)
 672     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 673      struct bfd_link_hash_entry *inh,
 674      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 675   /* Error or warning link info message.  */
 676   void (*einfo)
 677     (const char *fmt, ...);
 678   /* General link info message.  */
 679   void (*info)
 680     (const char *fmt, ...);
 681   /* Message to be printed in linker map file.  */
 682   void (*minfo)
 683     (const char *fmt, ...);
 684   /* This callback provides a chance for users of the BFD library to
 685      override its decision about whether to place two adjacent sections
 686      into the same segment.  */
 687   bfd_boolean (*override_segment_assignment)
 688     (struct bfd_link_info *, bfd * abfd,
 689      asection * current_section, asection * previous_section,
 690      bfd_boolean new_segment);
 691 };
 692 \f
 693 /* The linker builds link_order structures which tell the code how to
 694    include input data in the output file.  */
 695
 696 /* These are the types of link_order structures.  */
 697
 698 enum bfd_link_order_type
 699 {
 700   bfd_undefined_link_order,     /* Undefined.  */
 701   bfd_indirect_link_order,      /* Built from a section.  */
 702   bfd_data_link_order,          /* Set to explicit data.  */
 703   bfd_section_reloc_link_order, /* Relocate against a section.  */
 704   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 705 };
 706
 707 /* This is the link_order structure itself.  These form a chain
 708    attached to the output section whose contents they are describing.  */
 709
 710 struct bfd_link_order
 711 {
 712   /* Next link_order in chain.  */
 713   struct bfd_link_order *next;
 714   /* Type of link_order.  */
 715   enum bfd_link_order_type type;
 716   /* Offset within output section.  */
 717   bfd_vma offset;
 718   /* Size within output section.  */
 719   bfd_size_type size;
 720   /* Type specific information.  */
 721   union
 722     {
 723       struct
 724         {
 725           /* Section to include.  If this is used, then
 726              section->output_section must be the section the
 727              link_order is attached to, section->output_offset must
 728              equal the link_order offset field, and section->size
 729              must equal the link_order size field.  Maybe these
 730              restrictions should be relaxed someday.  */
 731           asection *section;
 732         } indirect;
 733       struct
 734         {
 735           /* Size of contents, or zero when contents should be filled by
 736              the architecture-dependent fill function.
 737              A non-zero value allows filling of the output section
 738              with an arbitrary repeated pattern.  */
 739           unsigned int size;
 740           /* Data to put into file.  */
 741           bfd_byte *contents;
 742         } data;
 743       struct
 744         {
 745           /* Description of reloc to generate.  Used for
 746              bfd_section_reloc_link_order and
 747              bfd_symbol_reloc_link_order.  */
 748           struct bfd_link_order_reloc *p;
 749         } reloc;
 750     } u;
 751 };
 752
 753 /* A linker order of type bfd_section_reloc_link_order or
 754    bfd_symbol_reloc_link_order means to create a reloc against a
 755    section or symbol, respectively.  This is used to implement -Ur to
 756    generate relocs for the constructor tables.  The
 757    bfd_link_order_reloc structure describes the reloc that BFD should
 758    create.  It is similar to a arelent, but I didn't use arelent
 759    because the linker does not know anything about most symbols, and
 760    any asymbol structure it creates will be partially meaningless.
 761    This information could logically be in the bfd_link_order struct,
 762    but I didn't want to waste the space since these types of relocs
 763    are relatively rare.  */
 764
 765 struct bfd_link_order_reloc
 766 {
 767   /* Reloc type.  */
 768   bfd_reloc_code_real_type reloc;
 769
 770   union
 771     {
 772       /* For type bfd_section_reloc_link_order, this is the section
 773          the reloc should be against.  This must be a section in the
 774          output BFD, not any of the input BFDs.  */
 775       asection *section;
 776       /* For type bfd_symbol_reloc_link_order, this is the name of the
 777          symbol the reloc should be against.  */
 778       const char *name;
 779     } u;
 780
 781   /* Addend to use.  The object file should contain zero.  The BFD
 782      backend is responsible for filling in the contents of the object
 783      file correctly.  For some object file formats (e.g., COFF) the
 784      addend must be stored into in the object file, and for some
 785      (e.g., SPARC a.out) it is kept in the reloc.  */
 786   bfd_vma addend;
 787 };
 788
 789 /* Allocate a new link_order for a section.  */
 790 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 791
 792 /* These structures are used to describe version information for the
 793    ELF linker.  These structures could be manipulated entirely inside
 794    BFD, but it would be a pain.  Instead, the regular linker sets up
 795    these structures, and then passes them into BFD.  */
 796
 797 /* Glob pattern for a version.  */
 798
 799 struct bfd_elf_version_expr
 800 {
 801   /* Next glob pattern for this version.  */
 802   struct bfd_elf_version_expr *next;
 803   /* Glob pattern.  */
 804   const char *pattern;
 805   /* Set if pattern is not a glob.  */
 806   unsigned int literal : 1;
 807   /* Defined by ".symver".  */
 808   unsigned int symver : 1;
 809   /* Defined by version script.  */
 810   unsigned int script : 1;
 811   /* Pattern type.  */
 812 #define BFD_ELF_VERSION_C_TYPE          1
 813 #define BFD_ELF_VERSION_CXX_TYPE        2
 814 #define BFD_ELF_VERSION_JAVA_TYPE       4
 815   unsigned int mask : 3;
 816 };
 817
 818 struct bfd_elf_version_expr_head
 819 {
 820   /* List of all patterns, both wildcards and non-wildcards.  */
 821   struct bfd_elf_version_expr *list;
 822   /* Hash table for non-wildcards.  */
 823   void *htab;
 824   /* Remaining patterns.  */
 825   struct bfd_elf_version_expr *remaining;
 826   /* What kind of pattern types are present in list (bitmask).  */
 827   unsigned int mask;
 828 };
 829
 830 /* Version dependencies.  */
 831
 832 struct bfd_elf_version_deps
 833 {
 834   /* Next dependency for this version.  */
 835   struct bfd_elf_version_deps *next;
 836   /* The version which this version depends upon.  */
 837   struct bfd_elf_version_tree *version_needed;
 838 };
 839
 840 /* A node in the version tree.  */
 841
 842 struct bfd_elf_version_tree
 843 {
 844   /* Next version.  */
 845   struct bfd_elf_version_tree *next;
 846   /* Name of this version.  */
 847   const char *name;
 848   /* Version number.  */
 849   unsigned int vernum;
 850   /* Regular expressions for global symbols in this version.  */
 851   struct bfd_elf_version_expr_head globals;
 852   /* Regular expressions for local symbols in this version.  */
 853   struct bfd_elf_version_expr_head locals;
 854   /* List of versions which this version depends upon.  */
 855   struct bfd_elf_version_deps *deps;
 856   /* Index of the version name.  This is used within BFD.  */
 857   unsigned int name_indx;
 858   /* Whether this version tree was used.  This is used within BFD.  */
 859   int used;
 860   /* Matching hook.  */
 861   struct bfd_elf_version_expr *(*match)
 862     (struct bfd_elf_version_expr_head *head,
 863      struct bfd_elf_version_expr *prev, const char *sym);
 864 };
 865
 866 struct bfd_elf_dynamic_list
 867 {
 868   struct bfd_elf_version_expr_head head;
 869   struct bfd_elf_version_expr *(*match)
 870     (struct bfd_elf_version_expr_head *head,
 871      struct bfd_elf_version_expr *prev, const char *sym);
 872 };
 873
 874 #endif