include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003,
   3    2004, 2005 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
  85   /* Type of this entry.  */
  86   enum bfd_link_hash_type type;
  87
  88   /* A union of information depending upon the type.  */
  89   union
  90     {
  91       /* Nothing is kept for bfd_hash_new.  */
  92       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
  93       struct
  94         {
  95           /* Undefined and common symbols are kept in a linked list through
  96              this field.  This field is present in all of the union element
  97              so that we don't need to remove entries from the list when we
  98              change their type.  Removing entries would either require the
  99              list to be doubly linked, which would waste more memory, or
 100              require a traversal.  When an undefined or common symbol is
 101              created, it should be added to this list, the head of which is in
 102              the link hash table itself.  As symbols are defined, they need
 103              not be removed from the list; anything which reads the list must
 104              doublecheck the symbol type.
 105
 106              Weak symbols are not kept on this list.
 107
 108              Defined and defweak symbols use this field as a reference marker.
 109              If the field is not NULL, or this structure is the tail of the
 110              undefined symbol list, the symbol has been referenced.  If the
 111              symbol is undefined and becomes defined, this field will
 112              automatically be non-NULL since the symbol will have been on the
 113              undefined symbol list.  */
 114           struct bfd_link_hash_entry *next;
 115           bfd *abfd;            /* BFD symbol was found in.  */
 116         } undef;
 117       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 118       struct
 119         {
 120           struct bfd_link_hash_entry *next;
 121           asection *section;    /* Symbol section.  */
 122           bfd_vma value;        /* Symbol value.  */
 123         } def;
 124       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 125       struct
 126         {
 127           struct bfd_link_hash_entry *next;
 128           struct bfd_link_hash_entry *link;     /* Real symbol.  */
 129           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
 130         } i;
 131       /* bfd_link_hash_common.  */
 132       struct
 133         {
 134           struct bfd_link_hash_entry *next;
 135           /* The linker needs to know three things about common
 136              symbols: the size, the alignment, and the section in
 137              which the symbol should be placed.  We store the size
 138              here, and we allocate a small structure to hold the
 139              section and the alignment.  The alignment is stored as a
 140              power of two.  We don't store all the information
 141              directly because we don't want to increase the size of
 142              the union; this structure is a major space user in the
 143              linker.  */
 144           struct bfd_link_hash_common_entry
 145             {
 146               unsigned int alignment_power;     /* Alignment.  */
 147               asection *section;                /* Symbol section.  */
 148             } *p;
 149           bfd_size_type size;   /* Common symbol size.  */
 150         } c;
 151     } u;
 152 };
 153
 154 /* This is the link hash table.  It is a derived class of
 155    bfd_hash_table.  */
 156
 157 struct bfd_link_hash_table
 158 {
 159   /* The hash table itself.  */
 160   struct bfd_hash_table table;
 161   /* The back end which created this hash table.  This indicates the
 162      type of the entries in the hash table, which is sometimes
 163      important information when linking object files of different
 164      types together.  */
 165   const bfd_target *creator;
 166   /* A linked list of undefined and common symbols, linked through the
 167      next field in the bfd_link_hash_entry structure.  */
 168   struct bfd_link_hash_entry *undefs;
 169   /* Entries are added to the tail of the undefs list.  */
 170   struct bfd_link_hash_entry *undefs_tail;
 171   /* The type of the link hash table.  */
 172   enum bfd_link_hash_table_type type;
 173 };
 174
 175 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 176    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 177    the real symbol.  */
 178 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 179   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
 180    bfd_boolean copy, bfd_boolean follow);
 181
 182 /* Look up an entry in the main linker hash table if the symbol might
 183    be wrapped.  This should only be used for references to an
 184    undefined symbol, not for definitions of a symbol.  */
 185
 186 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 187   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
 188    bfd_boolean, bfd_boolean);
 189
 190 /* Traverse a link hash table.  */
 191 extern void bfd_link_hash_traverse
 192   (struct bfd_link_hash_table *,
 193     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
 194     void *);
 195
 196 /* Add an entry to the undefs list.  */
 197 extern void bfd_link_add_undef
 198   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 199
 200 /* Remove symbols from the undefs list that don't belong there.  */
 201 extern void bfd_link_repair_undef_list
 202   (struct bfd_link_hash_table *table);
 203
 204 struct bfd_sym_chain
 205 {
 206   struct bfd_sym_chain *next;
 207   const char *name;
 208 };
 209 \f
 210 /* How to handle unresolved symbols.
 211    There are four possibilities which are enumerated below:  */
 212 enum report_method
 213 {
 214   /* This is the initial value when then link_info structure is created.
 215      It allows the various stages of the linker to determine whether they
 216      allowed to set the value.  */
 217   RM_NOT_YET_SET = 0,
 218   RM_IGNORE,
 219   RM_GENERATE_WARNING,
 220   RM_GENERATE_ERROR
 221 };
 222
 223 /* This structure holds all the information needed to communicate
 224    between BFD and the linker when doing a link.  */
 225
 226 struct bfd_link_info
 227 {
 228   /* TRUE if BFD should generate a relocatable object file.  */
 229   unsigned int relocatable: 1;
 230
 231   /* TRUE if BFD should generate relocation information in the final
 232      executable.  */
 233   unsigned int emitrelocations: 1;
 234
 235   /* TRUE if BFD should generate a "task linked" object file,
 236      similar to relocatable but also with globals converted to
 237      statics.  */
 238   unsigned int task_link: 1;
 239
 240   /* TRUE if BFD should generate a shared object.  */
 241   unsigned int shared: 1;
 242
 243   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 244   unsigned int symbolic: 1;
 245
 246   /* TRUE if BFD should export all symbols in the dynamic symbol table
 247      of an executable, rather than only those used.  */
 248   unsigned int export_dynamic: 1;
 249
 250   /* TRUE if shared objects should be linked directly, not shared.  */
 251   unsigned int static_link: 1;
 252
 253   /* TRUE if the output file should be in a traditional format.  This
 254      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 255      on the output file, but may be checked when reading the input
 256      files.  */
 257   unsigned int traditional_format: 1;
 258
 259   /* TRUE if we want to produced optimized output files.  This might
 260      need much more time and therefore must be explicitly selected.  */
 261   unsigned int optimize: 1;
 262
 263   /* TRUE if ok to have multiple definition.  */
 264   unsigned int allow_multiple_definition: 1;
 265
 266   /* TRUE if ok to have version with no definition.  */
 267   unsigned int allow_undefined_version: 1;
 268
 269   /* TRUE if a default symbol version should be created and used for
 270      exported symbols.  */
 271   unsigned int create_default_symver: 1;
 272
 273   /* TRUE if a default symbol version should be created and used for
 274      imported symbols.  */
 275   unsigned int default_imported_symver: 1;
 276
 277   /* TRUE if symbols should be retained in memory, FALSE if they
 278      should be freed and reread.  */
 279   unsigned int keep_memory: 1;
 280
 281   /* TRUE if every symbol should be reported back via the notice
 282      callback.  */
 283   unsigned int notice_all: 1;
 284
 285   /* TRUE if executable should not contain copy relocs.
 286      Setting this true may result in a non-sharable text segment.  */
 287   unsigned int nocopyreloc: 1;
 288
 289   /* TRUE if the new ELF dynamic tags are enabled. */
 290   unsigned int new_dtags: 1;
 291
 292   /* TRUE if non-PLT relocs should be merged into one reloc section
 293      and sorted so that relocs against the same symbol come together.  */
 294   unsigned int combreloc: 1;
 295
 296   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 297      should be created.  */
 298   unsigned int eh_frame_hdr: 1;
 299
 300   /* TRUE if global symbols in discarded sections should be stripped.  */
 301   unsigned int strip_discarded: 1;
 302
 303   /* TRUE if the final relax pass is needed.  */
 304   unsigned int need_relax_finalize: 1;
 305
 306   /* TRUE if generating a position independent executable.  */
 307   unsigned int pie: 1;
 308
 309   /* TRUE if generating an executable, position independent or not.  */
 310   unsigned int executable : 1;
 311
 312   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
 313      flags.  */
 314   unsigned int execstack: 1;
 315
 316   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
 317      flags.  */
 318   unsigned int noexecstack: 1;
 319
 320   /* TRUE if PT_GNU_RELRO segment should be created.  */
 321   unsigned int relro: 1;
 322
 323   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
 324   unsigned int warn_shared_textrel: 1;
 325
 326   /* What to do with unresolved symbols in an object file.
 327      When producing executables the default is GENERATE_ERROR.
 328      When producing shared libraries the default is IGNORE.  The
 329      assumption with shared libraries is that the reference will be
 330      resolved at load/execution time.  */
 331   enum report_method unresolved_syms_in_objects;
 332
 333   /* What to do with unresolved symbols in a shared library.
 334      The same defaults apply.  */
 335   enum report_method unresolved_syms_in_shared_libs;
 336
 337   /* Which symbols to strip.  */
 338   enum bfd_link_strip strip;
 339
 340   /* Which local symbols to discard.  */
 341   enum bfd_link_discard discard;
 342
 343   /* Criteria for skipping symbols when detemining
 344      whether to include an object from an archive. */
 345   enum bfd_link_common_skip_ar_aymbols common_skip_ar_aymbols;
 346
 347   /* Char that may appear as the first char of a symbol, but should be
 348      skipped (like symbol_leading_char) when looking up symbols in
 349      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 350   char wrap_char;
 351
 352   /* Function callbacks.  */
 353   const struct bfd_link_callbacks *callbacks;
 354
 355   /* Hash table handled by BFD.  */
 356   struct bfd_link_hash_table *hash;
 357
 358   /* Hash table of symbols to keep.  This is NULL unless strip is
 359      strip_some.  */
 360   struct bfd_hash_table *keep_hash;
 361
 362   /* Hash table of symbols to report back via the notice callback.  If
 363      this is NULL, and notice_all is FALSE, then no symbols are
 364      reported back.  */
 365   struct bfd_hash_table *notice_hash;
 366
 367   /* Hash table of symbols which are being wrapped (the --wrap linker
 368      option).  If this is NULL, no symbols are being wrapped.  */
 369   struct bfd_hash_table *wrap_hash;
 370
 371   /* The list of input BFD's involved in the link.  These are chained
 372      together via the link_next field.  */
 373   bfd *input_bfds;
 374
 375   /* If a symbol should be created for each input BFD, this is section
 376      where those symbols should be placed.  It must be a section in
 377      the output BFD.  It may be NULL, in which case no such symbols
 378      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 379      linker command language.  */
 380   asection *create_object_symbols_section;
 381
 382   /* List of global symbol names that are starting points for marking
 383      sections against garbage collection.  */
 384   struct bfd_sym_chain *gc_sym_list;
 385
 386   /* If a base output file is wanted, then this points to it */
 387   void *base_file;
 388
 389   /* The function to call when the executable or shared object is
 390      loaded.  */
 391   const char *init_function;
 392
 393   /* The function to call when the executable or shared object is
 394      unloaded.  */
 395   const char *fini_function;
 396
 397   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 398      should be generated/linked against.  Set to 1 if this feature
 399      is explicitly requested by the user, -1 if enabled by default.  */
 400   int pei386_auto_import;
 401
 402   /* Non-zero if runtime relocs for DATA items with non-zero addends
 403      in pei386 DLLs should be generated.  Set to 1 if this feature
 404      is explicitly requested by the user, -1 if enabled by default.  */
 405   int pei386_runtime_pseudo_reloc;
 406
 407   /* How many spare .dynamic DT_NULL entries should be added?  */
 408   unsigned int spare_dynamic_tags;
 409
 410   /* May be used to set DT_FLAGS for ELF. */
 411   bfd_vma flags;
 412
 413   /* May be used to set DT_FLAGS_1 for ELF. */
 414   bfd_vma flags_1;
 415
 416   /* Start and end of RELRO region.  */
 417   bfd_vma relro_start, relro_end;
 418 };
 419
 420 /* This structures holds a set of callback functions.  These are
 421    called by the BFD linker routines.  The first argument to each
 422    callback function is the bfd_link_info structure being used.  Each
 423    function returns a boolean value.  If the function returns FALSE,
 424    then the BFD function which called it will return with a failure
 425    indication.  */
 426
 427 struct bfd_link_callbacks
 428 {
 429   /* A function which is called when an object is added from an
 430      archive.  ABFD is the archive element being added.  NAME is the
 431      name of the symbol which caused the archive element to be pulled
 432      in.  */
 433   bfd_boolean (*add_archive_element)
 434     (struct bfd_link_info *, bfd *abfd, const char *name);
 435   /* A function which is called when a symbol is found with multiple
 436      definitions.  NAME is the symbol which is defined multiple times.
 437      OBFD is the old BFD, OSEC is the old section, OVAL is the old
 438      value, NBFD is the new BFD, NSEC is the new section, and NVAL is
 439      the new value.  OBFD may be NULL.  OSEC and NSEC may be
 440      bfd_com_section or bfd_ind_section.  */
 441   bfd_boolean (*multiple_definition)
 442     (struct bfd_link_info *, const char *name,
 443      bfd *obfd, asection *osec, bfd_vma oval,
 444      bfd *nbfd, asection *nsec, bfd_vma nval);
 445   /* A function which is called when a common symbol is defined
 446      multiple times.  NAME is the symbol appearing multiple times.
 447      OBFD is the BFD of the existing symbol; it may be NULL if this is
 448      not known.  OTYPE is the type of the existing symbol, which may
 449      be bfd_link_hash_defined, bfd_link_hash_defweak,
 450      bfd_link_hash_common, or bfd_link_hash_indirect.  If OTYPE is
 451      bfd_link_hash_common, OSIZE is the size of the existing symbol.
 452      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 453      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 454      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 455      is the size of the new symbol.  */
 456   bfd_boolean (*multiple_common)
 457     (struct bfd_link_info *, const char *name,
 458      bfd *obfd, enum bfd_link_hash_type otype, bfd_vma osize,
 459      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 460   /* A function which is called to add a symbol to a set.  ENTRY is
 461      the link hash table entry for the set itself (e.g.,
 462      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 463      the set when generating a relocatable file, and is also used to
 464      get the size of the entry when generating an executable file.
 465      ABFD, SEC and VALUE identify the value to add to the set.  */
 466   bfd_boolean (*add_to_set)
 467     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 468      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 469   /* A function which is called when the name of a g++ constructor or
 470      destructor is found.  This is only called by some object file
 471      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 472      destructor.  This will use BFD_RELOC_CTOR when generating a
 473      relocatable file.  NAME is the name of the symbol found.  ABFD,
 474      SECTION and VALUE are the value of the symbol.  */
 475   bfd_boolean (*constructor)
 476     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
 477      bfd *abfd, asection *sec, bfd_vma value);
 478   /* A function which is called to issue a linker warning.  For
 479      example, this is called when there is a reference to a warning
 480      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 481      of the symbol which triggered the warning; it may be NULL if
 482      there is none.  ABFD, SECTION and ADDRESS identify the location
 483      which trigerred the warning; either ABFD or SECTION or both may
 484      be NULL if the location is not known.  */
 485   bfd_boolean (*warning)
 486     (struct bfd_link_info *, const char *warning, const char *symbol,
 487      bfd *abfd, asection *section, bfd_vma address);
 488   /* A function which is called when a relocation is attempted against
 489      an undefined symbol.  NAME is the symbol which is undefined.
 490      ABFD, SECTION and ADDRESS identify the location from which the
 491      reference is made. FATAL indicates whether an undefined symbol is
 492      a fatal error or not. In some cases SECTION may be NULL.  */
 493   bfd_boolean (*undefined_symbol)
 494     (struct bfd_link_info *, const char *name, bfd *abfd,
 495      asection *section, bfd_vma address, bfd_boolean fatal);
 496   /* A function which is called when a reloc overflow occurs. ENTRY is
 497      the link hash table entry for the symbol the reloc is against.
 498      NAME is the name of the local symbol or section the reloc is
 499      against, RELOC_NAME is the name of the relocation, and ADDEND is
 500      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 501      location at which the overflow occurs; if this is the result of a
 502      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 503      ABFD will be NULL.  */
 504   bfd_boolean (*reloc_overflow)
 505     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 506      const char *name, const char *reloc_name, bfd_vma addend,
 507      bfd *abfd, asection *section, bfd_vma address);
 508   /* A function which is called when a dangerous reloc is performed.
 509      The canonical example is an a29k IHCONST reloc which does not
 510      follow an IHIHALF reloc.  MESSAGE is an appropriate message.
 511      ABFD, SECTION and ADDRESS identify the location at which the
 512      problem occurred; if this is the result of a
 513      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 514      ABFD will be NULL.  */
 515   bfd_boolean (*reloc_dangerous)
 516     (struct bfd_link_info *, const char *message,
 517      bfd *abfd, asection *section, bfd_vma address);
 518   /* A function which is called when a reloc is found to be attached
 519      to a symbol which is not being written out.  NAME is the name of
 520      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 521      the reloc; if this is the result of a
 522      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 523      ABFD will be NULL.  */
 524   bfd_boolean (*unattached_reloc)
 525     (struct bfd_link_info *, const char *name,
 526      bfd *abfd, asection *section, bfd_vma address);
 527   /* A function which is called when a symbol in notice_hash is
 528      defined or referenced.  NAME is the symbol.  ABFD, SECTION and
 529      ADDRESS are the value of the symbol.  If SECTION is
 530      bfd_und_section, this is a reference.  */
 531   bfd_boolean (*notice)
 532     (struct bfd_link_info *, const char *name,
 533      bfd *abfd, asection *section, bfd_vma address);
 534 };
 535 \f
 536 /* The linker builds link_order structures which tell the code how to
 537    include input data in the output file.  */
 538
 539 /* These are the types of link_order structures.  */
 540
 541 enum bfd_link_order_type
 542 {
 543   bfd_undefined_link_order,     /* Undefined.  */
 544   bfd_indirect_link_order,      /* Built from a section.  */
 545   bfd_data_link_order,          /* Set to explicit data.  */
 546   bfd_section_reloc_link_order, /* Relocate against a section.  */
 547   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 548 };
 549
 550 /* This is the link_order structure itself.  These form a chain
 551    attached to the section whose contents they are describing.  */
 552
 553 struct bfd_link_order
 554 {
 555   /* Next link_order in chain.  */
 556   struct bfd_link_order *next;
 557   /* Type of link_order.  */
 558   enum bfd_link_order_type type;
 559   /* Offset within output section.  */
 560   bfd_vma offset;
 561   /* Size within output section.  */
 562   bfd_size_type size;
 563   /* Type specific information.  */
 564   union
 565     {
 566       struct
 567         {
 568           /* Section to include.  If this is used, then
 569              section->output_section must be the section the
 570              link_order is attached to, section->output_offset must
 571              equal the link_order offset field, and section->size
 572              must equal the link_order size field.  Maybe these
 573              restrictions should be relaxed someday.  */
 574           asection *section;
 575         } indirect;
 576       struct
 577         {
 578           /* Size of contents, or zero when contents size == size
 579              within output section.
 580              A non-zero value allows filling of the output section
 581              with an arbitrary repeated pattern.  */
 582           unsigned int size;
 583           /* Data to put into file.  */
 584           bfd_byte *contents;
 585         } data;
 586       struct
 587         {
 588           /* Description of reloc to generate.  Used for
 589              bfd_section_reloc_link_order and
 590              bfd_symbol_reloc_link_order.  */
 591           struct bfd_link_order_reloc *p;
 592         } reloc;
 593     } u;
 594 };
 595
 596 /* A linker order of type bfd_section_reloc_link_order or
 597    bfd_symbol_reloc_link_order means to create a reloc against a
 598    section or symbol, respectively.  This is used to implement -Ur to
 599    generate relocs for the constructor tables.  The
 600    bfd_link_order_reloc structure describes the reloc that BFD should
 601    create.  It is similar to a arelent, but I didn't use arelent
 602    because the linker does not know anything about most symbols, and
 603    any asymbol structure it creates will be partially meaningless.
 604    This information could logically be in the bfd_link_order struct,
 605    but I didn't want to waste the space since these types of relocs
 606    are relatively rare.  */
 607
 608 struct bfd_link_order_reloc
 609 {
 610   /* Reloc type.  */
 611   bfd_reloc_code_real_type reloc;
 612
 613   union
 614     {
 615       /* For type bfd_section_reloc_link_order, this is the section
 616          the reloc should be against.  This must be a section in the
 617          output BFD, not any of the input BFDs.  */
 618       asection *section;
 619       /* For type bfd_symbol_reloc_link_order, this is the name of the
 620          symbol the reloc should be against.  */
 621       const char *name;
 622     } u;
 623
 624   /* Addend to use.  The object file should contain zero.  The BFD
 625      backend is responsible for filling in the contents of the object
 626      file correctly.  For some object file formats (e.g., COFF) the
 627      addend must be stored into in the object file, and for some
 628      (e.g., SPARC a.out) it is kept in the reloc.  */
 629   bfd_vma addend;
 630 };
 631
 632 /* Allocate a new link_order for a section.  */
 633 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
 634
 635 /* These structures are used to describe version information for the
 636    ELF linker.  These structures could be manipulated entirely inside
 637    BFD, but it would be a pain.  Instead, the regular linker sets up
 638    these structures, and then passes them into BFD.  */
 639
 640 /* Glob pattern for a version.  */
 641
 642 struct bfd_elf_version_expr
 643 {
 644   /* Next glob pattern for this version.  */
 645   struct bfd_elf_version_expr *next;
 646   /* Glob pattern.  */
 647   const char *pattern;
 648   /* NULL for a glob pattern, otherwise a straight symbol.  */
 649   const char *symbol;
 650   /* Defined by ".symver".  */
 651   unsigned int symver : 1;
 652   /* Defined by version script.  */
 653   unsigned int script : 1;
 654   /* Pattern type.  */
 655 #define BFD_ELF_VERSION_C_TYPE          1
 656 #define BFD_ELF_VERSION_CXX_TYPE        2
 657 #define BFD_ELF_VERSION_JAVA_TYPE       4
 658   unsigned int mask : 3;
 659 };
 660
 661 struct bfd_elf_version_expr_head
 662 {
 663   /* List of all patterns, both wildcards and non-wildcards.  */
 664   struct bfd_elf_version_expr *list;
 665   /* Hash table for non-wildcards.  */
 666   void *htab;
 667   /* Remaining patterns.  */
 668   struct bfd_elf_version_expr *remaining;
 669   /* What kind of pattern types are present in list (bitmask).  */
 670   unsigned int mask;
 671 };
 672
 673 /* Version dependencies.  */
 674
 675 struct bfd_elf_version_deps
 676 {
 677   /* Next dependency for this version.  */
 678   struct bfd_elf_version_deps *next;
 679   /* The version which this version depends upon.  */
 680   struct bfd_elf_version_tree *version_needed;
 681 };
 682
 683 /* A node in the version tree.  */
 684
 685 struct bfd_elf_version_tree
 686 {
 687   /* Next version.  */
 688   struct bfd_elf_version_tree *next;
 689   /* Name of this version.  */
 690   const char *name;
 691   /* Version number.  */
 692   unsigned int vernum;
 693   /* Regular expressions for global symbols in this version.  */
 694   struct bfd_elf_version_expr_head globals;
 695   /* Regular expressions for local symbols in this version.  */
 696   struct bfd_elf_version_expr_head locals;
 697   /* List of versions which this version depends upon.  */
 698   struct bfd_elf_version_deps *deps;
 699   /* Index of the version name.  This is used within BFD.  */
 700   unsigned int name_indx;
 701   /* Whether this version tree was used.  This is used within BFD.  */
 702   int used;
 703   /* Matching hook.  */
 704   struct bfd_elf_version_expr *(*match)
 705     (struct bfd_elf_version_expr_head *head,
 706      struct bfd_elf_version_expr *prev, const char *sym);
 707 };
 708
 709 #endif