include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002
   3    Free Software Foundation, Inc.
   4    Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
   5
   6    This file is part of BFD, the Binary File Descriptor library.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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_aymbols
  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 /* The linking routines use a hash table which uses this structure for
  78    its elements.  */
  79
  80 struct bfd_link_hash_entry
  81 {
  82   /* Base hash table entry structure.  */
  83   struct bfd_hash_entry root;
  84   /* Type of this entry.  */
  85   enum bfd_link_hash_type type;
  86
  87   /* Undefined and common symbols are kept in a linked list through
  88      this field.  This field is not in the union because that would
  89      force us to remove entries from the list when we changed their
  90      type, which would force the list to be doubly linked, which would
  91      waste more memory.  When an undefined or common symbol is
  92      created, it should be added to this list, the head of which is in
  93      the link hash table itself.  As symbols are defined, they need
  94      not be removed from the list; anything which reads the list must
  95      doublecheck the symbol type.
  96
  97      Weak symbols are not kept on this list.
  98
  99      Defined and defweak symbols use this field as a reference marker.
 100      If the field is not NULL, or this structure is the tail of the
 101      undefined symbol list, the symbol has been referenced.  If the
 102      symbol is undefined and becomes defined, this field will
 103      automatically be non-NULL since the symbol will have been on the
 104      undefined symbol list.  */
 105   struct bfd_link_hash_entry *next;
 106   /* A union of information depending upon the type.  */
 107   union
 108     {
 109       /* Nothing is kept for bfd_hash_new.  */
 110       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 111       struct
 112         {
 113           bfd *abfd;            /* BFD symbol was found in.  */
 114         } undef;
 115       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 116       struct
 117         {
 118           bfd_vma value;        /* Symbol value.  */
 119           asection *section;    /* Symbol section.  */
 120         } def;
 121       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 122       struct
 123         {
 124           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 125           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 126         } i;
 127       /* bfd_link_hash_common.  */
 128       struct
 129         {
 130           /* The linker needs to know three things about common
 131              symbols: the size, the alignment, and the section in
 132              which the symbol should be placed.  We store the size
 133              here, and we allocate a small structure to hold the
 134              section and the alignment.  The alignment is stored as a
 135              power of two.  We don't store all the information
 136              directly because we don't want to increase the size of
 137              the union; this structure is a major space user in the
 138              linker.  */
 139           bfd_size_type size;   /* Common symbol size.  */
 140           struct bfd_link_hash_common_entry
 141             {
 142               unsigned int alignment_power;     /* Alignment.  */
 143               asection *section;                /* Symbol section.  */
 144             } *p;
 145         } c;
 146     } u;
 147 };
 148
 149 /* This is the link hash table.  It is a derived class of
 150    bfd_hash_table.  */
 151
 152 struct bfd_link_hash_table
 153 {
 154   /* The hash table itself.  */
 155   struct bfd_hash_table table;
 156   /* The back end which created this hash table.  This indicates the
 157      type of the entries in the hash table, which is sometimes
 158      important information when linking object files of different
 159      types together.  */
 160   const bfd_target *creator;
 161   /* A linked list of undefined and common symbols, linked through the
 162      next field in the bfd_link_hash_entry structure.  */
 163   struct bfd_link_hash_entry *undefs;
 164   /* Entries are added to the tail of the undefs list.  */
 165   struct bfd_link_hash_entry *undefs_tail;
 166   /* The type of the ink hash table.  */
 167   enum bfd_link_hash_table_type type;
 168 };
 169
 170 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 171    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 172    the real symbol.  */
 173 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 174   PARAMS ((struct bfd_link_hash_table *, const char *, bfd_boolean create,
 175            bfd_boolean copy, bfd_boolean follow));
 176
 177 /* Look up an entry in the main linker hash table if the symbol might
 178    be wrapped.  This should only be used for references to an
 179    undefined symbol, not for definitions of a symbol.  */
 180
 181 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 182   PARAMS ((bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 183            bfd_boolean, bfd_boolean));
 184
 185 /* Traverse a link hash table.  */
 186 extern void bfd_link_hash_traverse
 187   PARAMS ((struct bfd_link_hash_table *,
 188            bfd_boolean (*) (struct bfd_link_hash_entry *, PTR),
 189            PTR));
 190
 191 /* Add an entry to the undefs list.  */
 192 extern void bfd_link_add_undef
 193   PARAMS ((struct bfd_link_hash_table *, struct bfd_link_hash_entry *));
 194
 195 struct bfd_sym_chain
 196 {
 197   struct bfd_sym_chain *next;
 198   const char *name;
 199 };
 200 \f
 201 /* This structure holds all the information needed to communicate
 202    between BFD and the linker when doing a link.  */
 203
 204 struct bfd_link_info
 205 {
 206   /* TRUE if BFD should generate a relocatable object file.  */
 207   unsigned int relocateable: 1;
 208
 209   /* TRUE if BFD should generate relocation information in the final
 210      executable.  */
 211   unsigned int emitrelocations: 1;
 212
 213   /* TRUE if BFD should generate a "task linked" object file,
 214      similar to relocatable but also with globals converted to
 215      statics.  */
 216   unsigned int task_link: 1;
 217
 218   /* TRUE if BFD should generate a shared object.  */
 219   unsigned int shared: 1;
 220
 221   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 222   unsigned int symbolic: 1;
 223
 224   /* TRUE if BFD should export all symbols in the dynamic symbol table
 225      of an executable, rather than only those used.  */
 226   unsigned int export_dynamic: 1;
 227
 228   /* TRUE if shared objects should be linked directly, not shared.  */
 229   unsigned int static_link: 1;
 230
 231   /* TRUE if the output file should be in a traditional format.  This
 232      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 233      on the output file, but may be checked when reading the input
 234      files.  */
 235   unsigned int traditional_format: 1;
 236
 237   /* TRUE if we want to produced optimized output files.  This might
 238      need much more time and therefore must be explicitly selected.  */
 239   unsigned int optimize: 1;
 240
 241   /* TRUE if BFD should generate errors for undefined symbols
 242      even if generating a shared object.  */
 243   unsigned int no_undefined: 1;
 244
 245   /* TRUE if BFD should allow undefined symbols in shared objects even
 246      when no_undefined is set to disallow undefined symbols.  The net
 247      result will be that undefined symbols in regular objects will
 248      still trigger an error, but undefined symbols in shared objects
 249      will be ignored.  The implementation of no_undefined makes the
 250      assumption that the runtime linker will choke on undefined
 251      symbols.  However there is at least one system (BeOS) where
 252      undefined symbols in shared libraries is normal since the kernel
 253      patches them at load time to select which function is most
 254      appropriate for the current architecture.  I.E. dynamically
 255      select an appropriate memset function.  Apparently it is also
 256      normal for HPPA shared libraries to have undefined symbols.  */
 257   unsigned int allow_shlib_undefined: 1;
 258
 259   /* TRUE if ok to have multiple definition.  */
 260   unsigned int allow_multiple_definition: 1;
 261
 262   /* TRUE if ok to have version with no definition.  */
 263   unsigned int allow_undefined_version: 1;
 264
 265   /* TRUE if symbols should be retained in memory, FALSE if they
 266      should be freed and reread.  */
 267   unsigned int keep_memory: 1;
 268
 269   /* TRUE if every symbol should be reported back via the notice
 270      callback.  */
 271   unsigned int notice_all: 1;
 272
 273   /* TRUE if executable should not contain copy relocs.
 274      Setting this true may result in a non-sharable text segment.  */
 275   unsigned int nocopyreloc: 1;
 276
 277   /* TRUE if the new ELF dynamic tags are enabled. */
 278   unsigned int new_dtags: 1;
 279
 280   /* TRUE if non-PLT relocs should be merged into one reloc section
 281      and sorted so that relocs against the same symbol come together.  */
 282   unsigned int combreloc: 1;
 283
 284   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 285      should be created.  */
 286   unsigned int eh_frame_hdr: 1;
 287
 288   /* TRUE if global symbols in discarded sections should be stripped.  */
 289   unsigned int strip_discarded: 1;
 290
 291   /* TRUE if relaxation is being finalized.  */
 292   unsigned int relax_finalizing: 1;
 293
 294   /* Which symbols to strip.  */
 295   enum bfd_link_strip strip;
 296
 297   /* Which local symbols to discard.  */
 298   enum bfd_link_discard discard;
 299
 300   /* Criteria for skipping symbols when detemining
 301      whether to include an object from an archive. */
 302   enum bfd_link_common_skip_ar_aymbols common_skip_ar_aymbols;
 303
 304   /* Function callbacks.  */
 305   const struct bfd_link_callbacks *callbacks;
 306
 307   /* Hash table handled by BFD.  */
 308   struct bfd_link_hash_table *hash;
 309
 310   /* Hash table of symbols to keep.  This is NULL unless strip is
 311      strip_some.  */
 312   struct bfd_hash_table *keep_hash;
 313
 314   /* Hash table of symbols to report back via the notice callback.  If
 315      this is NULL, and notice_all is FALSE, then no symbols are
 316      reported back.  */
 317   struct bfd_hash_table *notice_hash;
 318
 319   /* Hash table of symbols which are being wrapped (the --wrap linker
 320      option).  If this is NULL, no symbols are being wrapped.  */
 321   struct bfd_hash_table *wrap_hash;
 322
 323   /* The list of input BFD's involved in the link.  These are chained
 324      together via the link_next field.  */
 325   bfd *input_bfds;
 326
 327   /* If a symbol should be created for each input BFD, this is section
 328      where those symbols should be placed.  It must be a section in
 329      the output BFD.  It may be NULL, in which case no such symbols
 330      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 331      linker command language.  */
 332   asection *create_object_symbols_section;
 333
 334   /* List of global symbol names that are starting points for marking
 335      sections against garbage collection.  */
 336   struct bfd_sym_chain *gc_sym_list;
 337
 338   /* If a base output file is wanted, then this points to it */
 339   PTR base_file;
 340
 341   /* The function to call when the executable or shared object is
 342      loaded.  */
 343   const char *init_function;
 344
 345   /* The function to call when the executable or shared object is
 346      unloaded.  */
 347   const char *fini_function;
 348
 349   /* If non-zero, specifies that branches which are problematic for the
 350      MPC860 C0 (or earlier) should be checked for and modified.  It gives the
 351      number of bytes that should be checked at the end of each text page.  */
 352   int mpc860c0;
 353
 354   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 355      should be generated/linked against.  Set to 1 if this feature
 356      is explicitly requested by the user, -1 if enabled by default.  */
 357   int pei386_auto_import;
 358
 359   /* Non-zero if runtime relocs for DATA items with non-zero addends
 360      in pei386 DLLs should be generated.  Set to 1 if this feature
 361      is explicitly requested by the user, -1 if enabled by default.  */
 362   int pei386_runtime_pseudo_reloc;
 363
 364   /* How many spare .dynamic DT_NULL entries should be added?  */
 365   unsigned int spare_dynamic_tags;
 366
 367   /* May be used to set DT_FLAGS for ELF. */
 368   bfd_vma flags;
 369
 370   /* May be used to set DT_FLAGS_1 for ELF. */
 371   bfd_vma flags_1;
 372 };
 373
 374 /* This structures holds a set of callback functions.  These are
 375    called by the BFD linker routines.  The first argument to each
 376    callback function is the bfd_link_info structure being used.  Each
 377    function returns a boolean value.  If the function returns FALSE,
 378    then the BFD function which called it will return with a failure
 379    indication.  */
 380
 381 struct bfd_link_callbacks
 382 {
 383   /* A function which is called when an object is added from an
 384      archive.  ABFD is the archive element being added.  NAME is the
 385      name of the symbol which caused the archive element to be pulled
 386      in.  */
 387   bfd_boolean (*add_archive_element)
 388     PARAMS ((struct bfd_link_info *, bfd *abfd, const char *name));
 389   /* A function which is called when a symbol is found with multiple
 390      definitions.  NAME is the symbol which is defined multiple times.
 391      OBFD is the old BFD, OSEC is the old section, OVAL is the old
 392      value, NBFD is the new BFD, NSEC is the new section, and NVAL is
 393      the new value.  OBFD may be NULL.  OSEC and NSEC may be
 394      bfd_com_section or bfd_ind_section.  */
 395   bfd_boolean (*multiple_definition)
 396     PARAMS ((struct bfd_link_info *, const char *name,
 397              bfd *obfd, asection *osec, bfd_vma oval,
 398              bfd *nbfd, asection *nsec, bfd_vma nval));
 399   /* A function which is called when a common symbol is defined
 400      multiple times.  NAME is the symbol appearing multiple times.
 401      OBFD is the BFD of the existing symbol; it may be NULL if this is
 402      not known.  OTYPE is the type of the existing symbol, which may
 403      be bfd_link_hash_defined, bfd_link_hash_defweak,
 404      bfd_link_hash_common, or bfd_link_hash_indirect.  If OTYPE is
 405      bfd_link_hash_common, OSIZE is the size of the existing symbol.
 406      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 407      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 408      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 409      is the size of the new symbol.  */
 410   bfd_boolean (*multiple_common)
 411     PARAMS ((struct bfd_link_info *, const char *name,
 412              bfd *obfd, enum bfd_link_hash_type otype, bfd_vma osize,
 413              bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize));
 414   /* A function which is called to add a symbol to a set.  ENTRY is
 415      the link hash table entry for the set itself (e.g.,
 416      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 417      the set when generating a relocateable file, and is also used to
 418      get the size of the entry when generating an executable file.
 419      ABFD, SEC and VALUE identify the value to add to the set.  */
 420   bfd_boolean (*add_to_set)
 421     PARAMS ((struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 422              bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec,
 423              bfd_vma value));
 424   /* A function which is called when the name of a g++ constructor or
 425      destructor is found.  This is only called by some object file
 426      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 427      destructor.  This will use BFD_RELOC_CTOR when generating a
 428      relocateable file.  NAME is the name of the symbol found.  ABFD,
 429      SECTION and VALUE are the value of the symbol.  */
 430   bfd_boolean (*constructor)
 431     PARAMS ((struct bfd_link_info *, bfd_boolean constructor,
 432              const char *name, bfd *abfd, asection *sec, bfd_vma value));
 433   /* A function which is called to issue a linker warning.  For
 434      example, this is called when there is a reference to a warning
 435      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 436      of the symbol which triggered the warning; it may be NULL if
 437      there is none.  ABFD, SECTION and ADDRESS identify the location
 438      which trigerred the warning; either ABFD or SECTION or both may
 439      be NULL if the location is not known.  */
 440   bfd_boolean (*warning)
 441     PARAMS ((struct bfd_link_info *, const char *warning, const char *symbol,
 442              bfd *abfd, asection *section, bfd_vma address));
 443   /* A function which is called when a relocation is attempted against
 444      an undefined symbol.  NAME is the symbol which is undefined.
 445      ABFD, SECTION and ADDRESS identify the location from which the
 446      reference is made. FATAL indicates whether an undefined symbol is
 447      a fatal error or not. In some cases SECTION may be NULL.  */
 448   bfd_boolean (*undefined_symbol)
 449     PARAMS ((struct bfd_link_info *, const char *name, bfd *abfd,
 450              asection *section, bfd_vma address, bfd_boolean fatal));
 451   /* A function which is called when a reloc overflow occurs.  NAME is
 452      the name of the symbol or section the reloc is against,
 453      RELOC_NAME is the name of the relocation, and ADDEND is any
 454      addend that is used.  ABFD, SECTION and ADDRESS identify the
 455      location at which the overflow occurs; if this is the result of a
 456      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 457      ABFD will be NULL.  */
 458   bfd_boolean (*reloc_overflow)
 459     PARAMS ((struct bfd_link_info *, const char *name, const char *reloc_name,
 460              bfd_vma addend, bfd *abfd, asection *section, bfd_vma address));
 461   /* A function which is called when a dangerous reloc is performed.
 462      The canonical example is an a29k IHCONST reloc which does not
 463      follow an IHIHALF reloc.  MESSAGE is an appropriate message.
 464      ABFD, SECTION and ADDRESS identify the location at which the
 465      problem occurred; if this is the result of a
 466      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 467      ABFD will be NULL.  */
 468   bfd_boolean (*reloc_dangerous)
 469     PARAMS ((struct bfd_link_info *, const char *message,
 470              bfd *abfd, asection *section, bfd_vma address));
 471   /* A function which is called when a reloc is found to be attached
 472      to a symbol which is not being written out.  NAME is the name of
 473      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 474      the reloc; if this is the result of a
 475      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 476      ABFD will be NULL.  */
 477   bfd_boolean (*unattached_reloc)
 478     PARAMS ((struct bfd_link_info *, const char *name,
 479              bfd *abfd, asection *section, bfd_vma address));
 480   /* A function which is called when a symbol in notice_hash is
 481      defined or referenced.  NAME is the symbol.  ABFD, SECTION and
 482      ADDRESS are the value of the symbol.  If SECTION is
 483      bfd_und_section, this is a reference.  */
 484   bfd_boolean (*notice)
 485     PARAMS ((struct bfd_link_info *, const char *name,
 486              bfd *abfd, asection *section, bfd_vma address));
 487   /* A function which is called for reporting a linker error. ID is the
 488      error identifier. The remaining input is the same as einfo () in
 489      ld.  */
 490   bfd_boolean (*error_handler)
 491     PARAMS ((int id, const char * fmt, ...));
 492 };
 493 \f
 494 /* The linker builds link_order structures which tell the code how to
 495    include input data in the output file.  */
 496
 497 /* These are the types of link_order structures.  */
 498
 499 enum bfd_link_order_type
 500 {
 501   bfd_undefined_link_order,     /* Undefined.  */
 502   bfd_indirect_link_order,      /* Built from a section.  */
 503   bfd_data_link_order,          /* Set to explicit data.  */
 504   bfd_section_reloc_link_order, /* Relocate against a section.  */
 505   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 506 };
 507
 508 /* This is the link_order structure itself.  These form a chain
 509    attached to the section whose contents they are describing.  */
 510
 511 struct bfd_link_order
 512 {
 513   /* Next link_order in chain.  */
 514   struct bfd_link_order *next;
 515   /* Type of link_order.  */
 516   enum bfd_link_order_type type;
 517   /* Offset within output section.  */
 518   bfd_vma offset;
 519   /* Size within output section.  */
 520   bfd_size_type size;
 521   /* Type specific information.  */
 522   union
 523     {
 524       struct
 525         {
 526           /* Section to include.  If this is used, then
 527              section->output_section must be the section the
 528              link_order is attached to, section->output_offset must
 529              equal the link_order offset field, and section->_raw_size
 530              must equal the link_order size field.  Maybe these
 531              restrictions should be relaxed someday.  */
 532           asection *section;
 533         } indirect;
 534       struct
 535         {
 536           /* Size of contents, or zero when contents size == size
 537              within output section.
 538              A non-zero value allows filling of the output section
 539              with an arbitrary repeated pattern.  */
 540           unsigned int size;
 541           /* Data to put into file.  */
 542           bfd_byte *contents;
 543         } data;
 544       struct
 545         {
 546           /* Description of reloc to generate.  Used for
 547              bfd_section_reloc_link_order and
 548              bfd_symbol_reloc_link_order.  */
 549           struct bfd_link_order_reloc *p;
 550         } reloc;
 551     } u;
 552 };
 553
 554 /* A linker order of type bfd_section_reloc_link_order or
 555    bfd_symbol_reloc_link_order means to create a reloc against a
 556    section or symbol, respectively.  This is used to implement -Ur to
 557    generate relocs for the constructor tables.  The
 558    bfd_link_order_reloc structure describes the reloc that BFD should
 559    create.  It is similar to a arelent, but I didn't use arelent
 560    because the linker does not know anything about most symbols, and
 561    any asymbol structure it creates will be partially meaningless.
 562    This information could logically be in the bfd_link_order struct,
 563    but I didn't want to waste the space since these types of relocs
 564    are relatively rare.  */
 565
 566 struct bfd_link_order_reloc
 567 {
 568   /* Reloc type.  */
 569   bfd_reloc_code_real_type reloc;
 570
 571   union
 572     {
 573       /* For type bfd_section_reloc_link_order, this is the section
 574          the reloc should be against.  This must be a section in the
 575          output BFD, not any of the input BFDs.  */
 576       asection *section;
 577       /* For type bfd_symbol_reloc_link_order, this is the name of the
 578          symbol the reloc should be against.  */
 579       const char *name;
 580     } u;
 581
 582   /* Addend to use.  The object file should contain zero.  The BFD
 583      backend is responsible for filling in the contents of the object
 584      file correctly.  For some object file formats (e.g., COFF) the
 585      addend must be stored into in the object file, and for some
 586      (e.g., SPARC a.out) it is kept in the reloc.  */
 587   bfd_vma addend;
 588 };
 589
 590 /* Allocate a new link_order for a section.  */
 591 extern struct bfd_link_order *bfd_new_link_order PARAMS ((bfd *, asection *));
 592
 593 /* These structures are used to describe version information for the
 594    ELF linker.  These structures could be manipulated entirely inside
 595    BFD, but it would be a pain.  Instead, the regular linker sets up
 596    these structures, and then passes them into BFD.  */
 597
 598 /* Regular expressions for a version.  */
 599
 600 struct bfd_elf_version_expr
 601 {
 602   /* Next regular expression for this version.  */
 603   struct bfd_elf_version_expr *next;
 604   /* Regular expression.  */
 605   const char *pattern;
 606   /* Matching function.  */
 607   int (*match) PARAMS ((struct bfd_elf_version_expr *, const char *));
 608   /* Defined by ".symver".  */
 609   unsigned int symver: 1;
 610   /* Defined by version script.  */
 611   unsigned int script : 1;
 612 };
 613
 614 /* Version dependencies.  */
 615
 616 struct bfd_elf_version_deps
 617 {
 618   /* Next dependency for this version.  */
 619   struct bfd_elf_version_deps *next;
 620   /* The version which this version depends upon.  */
 621   struct bfd_elf_version_tree *version_needed;
 622 };
 623
 624 /* A node in the version tree.  */
 625
 626 struct bfd_elf_version_tree
 627 {
 628   /* Next version.  */
 629   struct bfd_elf_version_tree *next;
 630   /* Name of this version.  */
 631   const char *name;
 632   /* Version number.  */
 633   unsigned int vernum;
 634   /* Regular expressions for global symbols in this version.  */
 635   struct bfd_elf_version_expr *globals;
 636   /* Regular expressions for local symbols in this version.  */
 637   struct bfd_elf_version_expr *locals;
 638   /* List of versions which this version depends upon.  */
 639   struct bfd_elf_version_deps *deps;
 640   /* Index of the version name.  This is used within BFD.  */
 641   unsigned int name_indx;
 642   /* Whether this version tree was used.  This is used within BFD.  */
 643   int used;
 644 };
 645
 646 #endif