holdingarea/llvm/llvm-gcc4.2-2.7-x86-mingw32/include/bfdlink.h
branchbug235_bringup_0
changeset 20 d2d6724aef32
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19:da7c1a80df0d 20:d2d6724aef32
       
     1 /* bfdlink.h -- header file for BFD link routines
       
     2    Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
       
     3    2003, 2004, 2005, 2006, 2007 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 3 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., 51 Franklin Street - Fifth Floor, Boston,
       
    21    MA 02110-1301, USA.  */
       
    22 
       
    23 #ifndef BFDLINK_H
       
    24 #define BFDLINK_H
       
    25 
       
    26 /* Which symbols to strip during a link.  */
       
    27 enum bfd_link_strip
       
    28 {
       
    29   strip_none,		/* Don't strip any symbols.  */
       
    30   strip_debugger,	/* Strip debugging symbols.  */
       
    31   strip_some,		/* keep_hash is the list of symbols to keep.  */
       
    32   strip_all		/* Strip all symbols.  */
       
    33 };
       
    34 
       
    35 /* Which local symbols to discard during a link.  This is irrelevant
       
    36    if strip_all is used.  */
       
    37 enum bfd_link_discard
       
    38 {
       
    39   discard_sec_merge,	/* Discard local temporary symbols in SEC_MERGE
       
    40 			   sections.  */
       
    41   discard_none,		/* Don't discard any locals.  */
       
    42   discard_l,		/* Discard local temporary symbols.  */
       
    43   discard_all		/* Discard all locals.  */
       
    44 };
       
    45 
       
    46 /* Describes the type of hash table entry structure being used.
       
    47    Different hash table structure have different fields and so
       
    48    support different linking features.  */
       
    49 enum bfd_link_hash_table_type
       
    50   {
       
    51     bfd_link_generic_hash_table,
       
    52     bfd_link_elf_hash_table
       
    53   };
       
    54 
       
    55 /* These are the possible types of an entry in the BFD link hash
       
    56    table.  */
       
    57 
       
    58 enum bfd_link_hash_type
       
    59 {
       
    60   bfd_link_hash_new,		/* Symbol is new.  */
       
    61   bfd_link_hash_undefined,	/* Symbol seen before, but undefined.  */
       
    62   bfd_link_hash_undefweak,	/* Symbol is weak and undefined.  */
       
    63   bfd_link_hash_defined,	/* Symbol is defined.  */
       
    64   bfd_link_hash_defweak,	/* Symbol is weak and defined.  */
       
    65   bfd_link_hash_common,		/* Symbol is common.  */
       
    66   bfd_link_hash_indirect,	/* Symbol is an indirect link.  */
       
    67   bfd_link_hash_warning		/* Like indirect, but warn if referenced.  */
       
    68 };
       
    69 
       
    70 enum bfd_link_common_skip_ar_aymbols
       
    71 {
       
    72   bfd_link_common_skip_none,
       
    73   bfd_link_common_skip_text,
       
    74   bfd_link_common_skip_data,
       
    75   bfd_link_common_skip_all
       
    76 };
       
    77 
       
    78 /* The linking routines use a hash table which uses this structure for
       
    79    its elements.  */
       
    80 
       
    81 struct bfd_link_hash_entry
       
    82 {
       
    83   /* Base hash table entry structure.  */
       
    84   struct bfd_hash_entry root;
       
    85 
       
    86   /* Type of this entry.  */
       
    87   enum bfd_link_hash_type type;
       
    88 
       
    89   /* A union of information depending upon the type.  */
       
    90   union
       
    91     {
       
    92       /* Nothing is kept for bfd_hash_new.  */
       
    93       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
       
    94       struct
       
    95 	{
       
    96 	  /* Undefined and common symbols are kept in a linked list through
       
    97 	     this field.  This field is present in all of the union element
       
    98 	     so that we don't need to remove entries from the list when we
       
    99 	     change their type.  Removing entries would either require the
       
   100 	     list to be doubly linked, which would waste more memory, or
       
   101 	     require a traversal.  When an undefined or common symbol is
       
   102 	     created, it should be added to this list, the head of which is in
       
   103 	     the link hash table itself.  As symbols are defined, they need
       
   104 	     not be removed from the list; anything which reads the list must
       
   105 	     doublecheck the symbol type.
       
   106 
       
   107 	     Weak symbols are not kept on this list.
       
   108 
       
   109 	     Defined and defweak symbols use this field as a reference marker.
       
   110 	     If the field is not NULL, or this structure is the tail of the
       
   111 	     undefined symbol list, the symbol has been referenced.  If the
       
   112 	     symbol is undefined and becomes defined, this field will
       
   113 	     automatically be non-NULL since the symbol will have been on the
       
   114 	     undefined symbol list.  */
       
   115 	  struct bfd_link_hash_entry *next;
       
   116 	  bfd *abfd;		/* BFD symbol was found in.  */
       
   117 	  bfd *weak;		/* BFD weak symbol was found in.  */
       
   118 	} undef;
       
   119       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
       
   120       struct
       
   121 	{
       
   122 	  struct bfd_link_hash_entry *next;
       
   123 	  asection *section;	/* Symbol section.  */
       
   124 	  bfd_vma value;	/* Symbol value.  */
       
   125 	} def;
       
   126       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
       
   127       struct
       
   128 	{
       
   129 	  struct bfd_link_hash_entry *next;
       
   130 	  struct bfd_link_hash_entry *link;	/* Real symbol.  */
       
   131 	  const char *warning;	/* Warning (bfd_link_hash_warning only).  */
       
   132 	} i;
       
   133       /* bfd_link_hash_common.  */
       
   134       struct
       
   135 	{
       
   136 	  struct bfd_link_hash_entry *next;
       
   137 	  /* The linker needs to know three things about common
       
   138 	     symbols: the size, the alignment, and the section in
       
   139 	     which the symbol should be placed.  We store the size
       
   140 	     here, and we allocate a small structure to hold the
       
   141 	     section and the alignment.  The alignment is stored as a
       
   142 	     power of two.  We don't store all the information
       
   143 	     directly because we don't want to increase the size of
       
   144 	     the union; this structure is a major space user in the
       
   145 	     linker.  */
       
   146 	  struct bfd_link_hash_common_entry
       
   147 	    {
       
   148 	      unsigned int alignment_power;	/* Alignment.  */
       
   149 	      asection *section;		/* Symbol section.  */
       
   150 	    } *p;
       
   151 	  bfd_size_type size;	/* Common symbol size.  */
       
   152 	} c;
       
   153     } u;
       
   154 };
       
   155 
       
   156 /* This is the link hash table.  It is a derived class of
       
   157    bfd_hash_table.  */
       
   158 
       
   159 struct bfd_link_hash_table
       
   160 {
       
   161   /* The hash table itself.  */
       
   162   struct bfd_hash_table table;
       
   163   /* The back end which created this hash table.  This indicates the
       
   164      type of the entries in the hash table, which is sometimes
       
   165      important information when linking object files of different
       
   166      types together.  */
       
   167   const bfd_target *creator;
       
   168   /* A linked list of undefined and common symbols, linked through the
       
   169      next field in the bfd_link_hash_entry structure.  */
       
   170   struct bfd_link_hash_entry *undefs;
       
   171   /* Entries are added to the tail of the undefs list.  */
       
   172   struct bfd_link_hash_entry *undefs_tail;
       
   173   /* The type of the link hash table.  */
       
   174   enum bfd_link_hash_table_type type;
       
   175 };
       
   176 
       
   177 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
       
   178    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
       
   179    the real symbol.  */
       
   180 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
       
   181   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
       
   182    bfd_boolean copy, bfd_boolean follow);
       
   183 
       
   184 /* Look up an entry in the main linker hash table if the symbol might
       
   185    be wrapped.  This should only be used for references to an
       
   186    undefined symbol, not for definitions of a symbol.  */
       
   187 
       
   188 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
       
   189   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
       
   190    bfd_boolean, bfd_boolean);
       
   191 
       
   192 /* Traverse a link hash table.  */
       
   193 extern void bfd_link_hash_traverse
       
   194   (struct bfd_link_hash_table *,
       
   195     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
       
   196     void *);
       
   197 
       
   198 /* Add an entry to the undefs list.  */
       
   199 extern void bfd_link_add_undef
       
   200   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
       
   201 
       
   202 /* Remove symbols from the undefs list that don't belong there.  */
       
   203 extern void bfd_link_repair_undef_list
       
   204   (struct bfd_link_hash_table *table);
       
   205 
       
   206 struct bfd_sym_chain
       
   207 {
       
   208   struct bfd_sym_chain *next;
       
   209   const char *name;
       
   210 };
       
   211 
       
   212 /* How to handle unresolved symbols.
       
   213    There are four possibilities which are enumerated below:  */
       
   214 enum report_method
       
   215 {
       
   216   /* This is the initial value when then link_info structure is created.
       
   217      It allows the various stages of the linker to determine whether they
       
   218      allowed to set the value.  */
       
   219   RM_NOT_YET_SET = 0,
       
   220   RM_IGNORE,
       
   221   RM_GENERATE_WARNING,
       
   222   RM_GENERATE_ERROR
       
   223 };
       
   224 
       
   225 struct bfd_elf_dynamic_list;
       
   226 
       
   227 /* This structure holds all the information needed to communicate
       
   228    between BFD and the linker when doing a link.  */
       
   229 
       
   230 struct bfd_link_info
       
   231 {
       
   232   /* TRUE if BFD should generate a relocatable object file.  */
       
   233   unsigned int relocatable: 1;
       
   234 
       
   235   /* TRUE if BFD should generate relocation information in the final
       
   236      executable.  */
       
   237   unsigned int emitrelocations: 1;
       
   238 
       
   239   /* TRUE if BFD should generate a "task linked" object file,
       
   240      similar to relocatable but also with globals converted to
       
   241      statics.  */
       
   242   unsigned int task_link: 1;
       
   243 
       
   244   /* TRUE if BFD should generate a shared object.  */
       
   245   unsigned int shared: 1;
       
   246 
       
   247   /* TRUE if BFD should pre-bind symbols in a shared object.  */
       
   248   unsigned int symbolic: 1;
       
   249 
       
   250   /* TRUE if BFD should export all symbols in the dynamic symbol table
       
   251      of an executable, rather than only those used.  */
       
   252   unsigned int export_dynamic: 1;
       
   253 
       
   254   /* TRUE if shared objects should be linked directly, not shared.  */
       
   255   unsigned int static_link: 1;
       
   256 
       
   257   /* TRUE if the output file should be in a traditional format.  This
       
   258      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
       
   259      on the output file, but may be checked when reading the input
       
   260      files.  */
       
   261   unsigned int traditional_format: 1;
       
   262 
       
   263   /* TRUE if we want to produced optimized output files.  This might
       
   264      need much more time and therefore must be explicitly selected.  */
       
   265   unsigned int optimize: 1;
       
   266 
       
   267   /* TRUE if ok to have multiple definition.  */
       
   268   unsigned int allow_multiple_definition: 1;
       
   269 
       
   270   /* TRUE if ok to have version with no definition.  */
       
   271   unsigned int allow_undefined_version: 1;
       
   272 
       
   273   /* TRUE if a default symbol version should be created and used for
       
   274      exported symbols.  */
       
   275   unsigned int create_default_symver: 1;
       
   276 
       
   277   /* TRUE if a default symbol version should be created and used for
       
   278      imported symbols.  */
       
   279   unsigned int default_imported_symver: 1;
       
   280 
       
   281   /* TRUE if symbols should be retained in memory, FALSE if they
       
   282      should be freed and reread.  */
       
   283   unsigned int keep_memory: 1;
       
   284 
       
   285   /* TRUE if every symbol should be reported back via the notice
       
   286      callback.  */
       
   287   unsigned int notice_all: 1;
       
   288 
       
   289   /* TRUE if executable should not contain copy relocs.
       
   290      Setting this true may result in a non-sharable text segment.  */
       
   291   unsigned int nocopyreloc: 1;
       
   292 
       
   293   /* TRUE if the new ELF dynamic tags are enabled. */
       
   294   unsigned int new_dtags: 1;
       
   295 
       
   296   /* TRUE if non-PLT relocs should be merged into one reloc section
       
   297      and sorted so that relocs against the same symbol come together.  */
       
   298   unsigned int combreloc: 1;
       
   299 
       
   300   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
       
   301      should be created.  */
       
   302   unsigned int eh_frame_hdr: 1;
       
   303 
       
   304   /* TRUE if global symbols in discarded sections should be stripped.  */
       
   305   unsigned int strip_discarded: 1;
       
   306 
       
   307   /* TRUE if generating a position independent executable.  */
       
   308   unsigned int pie: 1;
       
   309 
       
   310   /* TRUE if generating an executable, position independent or not.  */
       
   311   unsigned int executable : 1;
       
   312 
       
   313   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
       
   314      flags.  */
       
   315   unsigned int execstack: 1;
       
   316 
       
   317   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
       
   318      flags.  */
       
   319   unsigned int noexecstack: 1;
       
   320 
       
   321   /* TRUE if PT_GNU_RELRO segment should be created.  */
       
   322   unsigned int relro: 1;
       
   323 
       
   324   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
       
   325   unsigned int warn_shared_textrel: 1;
       
   326 
       
   327   /* TRUE if unreferenced sections should be removed.  */
       
   328   unsigned int gc_sections: 1;
       
   329 
       
   330   /* TRUE if user shoudl be informed of removed unreferenced sections.  */
       
   331   unsigned int print_gc_sections: 1;
       
   332 
       
   333   /* TRUE if .hash section should be created.  */
       
   334   unsigned int emit_hash: 1;
       
   335 
       
   336   /* TRUE if .gnu.hash section should be created.  */
       
   337   unsigned int emit_gnu_hash: 1;
       
   338 
       
   339   /* If TRUE reduce memory overheads, at the expense of speed. This will
       
   340      cause map file generation to use an O(N^2) algorithm and disable
       
   341      caching ELF symbol buffer.  */
       
   342   unsigned int reduce_memory_overheads: 1;
       
   343 
       
   344   /* TRUE if all data symbols should be dynamic.  */
       
   345    unsigned int dynamic_data: 1;
       
   346 
       
   347   /* TRUE if some symbols have to be dynamic, controlled by
       
   348      --dynamic-list command line options.  */
       
   349   unsigned int dynamic: 1;
       
   350 
       
   351   /* Non-NULL if .note.gnu.build-id section should be created.  */
       
   352   char *emit_note_gnu_build_id;
       
   353 
       
   354   /* What to do with unresolved symbols in an object file.
       
   355      When producing executables the default is GENERATE_ERROR.
       
   356      When producing shared libraries the default is IGNORE.  The
       
   357      assumption with shared libraries is that the reference will be
       
   358      resolved at load/execution time.  */
       
   359   enum report_method unresolved_syms_in_objects;
       
   360 
       
   361   /* What to do with unresolved symbols in a shared library.
       
   362      The same defaults apply.  */
       
   363   enum report_method unresolved_syms_in_shared_libs;
       
   364 
       
   365   /* Which symbols to strip.  */
       
   366   enum bfd_link_strip strip;
       
   367 
       
   368   /* Which local symbols to discard.  */
       
   369   enum bfd_link_discard discard;
       
   370 
       
   371   /* Criteria for skipping symbols when detemining
       
   372      whether to include an object from an archive. */
       
   373   enum bfd_link_common_skip_ar_aymbols common_skip_ar_aymbols;
       
   374 
       
   375   /* Char that may appear as the first char of a symbol, but should be
       
   376      skipped (like symbol_leading_char) when looking up symbols in
       
   377      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
       
   378   char wrap_char;
       
   379 
       
   380   /* Function callbacks.  */
       
   381   const struct bfd_link_callbacks *callbacks;
       
   382 
       
   383   /* Hash table handled by BFD.  */
       
   384   struct bfd_link_hash_table *hash;
       
   385 
       
   386   /* Hash table of symbols to keep.  This is NULL unless strip is
       
   387      strip_some.  */
       
   388   struct bfd_hash_table *keep_hash;
       
   389 
       
   390   /* Hash table of symbols to report back via the notice callback.  If
       
   391      this is NULL, and notice_all is FALSE, then no symbols are
       
   392      reported back.  */
       
   393   struct bfd_hash_table *notice_hash;
       
   394 
       
   395   /* Hash table of symbols which are being wrapped (the --wrap linker
       
   396      option).  If this is NULL, no symbols are being wrapped.  */
       
   397   struct bfd_hash_table *wrap_hash;
       
   398 
       
   399   /* The list of input BFD's involved in the link.  These are chained
       
   400      together via the link_next field.  */
       
   401   bfd *input_bfds;
       
   402   bfd **input_bfds_tail;
       
   403 
       
   404   /* If a symbol should be created for each input BFD, this is section
       
   405      where those symbols should be placed.  It must be a section in
       
   406      the output BFD.  It may be NULL, in which case no such symbols
       
   407      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
       
   408      linker command language.  */
       
   409   asection *create_object_symbols_section;
       
   410 
       
   411   /* List of global symbol names that are starting points for marking
       
   412      sections against garbage collection.  */
       
   413   struct bfd_sym_chain *gc_sym_list;
       
   414 
       
   415   /* If a base output file is wanted, then this points to it */
       
   416   void *base_file;
       
   417 
       
   418   /* The function to call when the executable or shared object is
       
   419      loaded.  */
       
   420   const char *init_function;
       
   421 
       
   422   /* The function to call when the executable or shared object is
       
   423      unloaded.  */
       
   424   const char *fini_function;
       
   425 
       
   426   /* Number of relaxation passes.  Usually only one relaxation pass
       
   427      is needed.  But a backend can have as many relaxation passes as
       
   428      necessary.  During bfd_relax_section call, it is set to the
       
   429      current pass, starting from 0.  */
       
   430   int relax_pass;
       
   431 
       
   432   /* Number of relaxation trips.  This number is incremented every
       
   433      time the relaxation pass is restarted due to a previous
       
   434      relaxation returning true in *AGAIN.  */
       
   435   int relax_trip;
       
   436 
       
   437   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
       
   438      should be generated/linked against.  Set to 1 if this feature
       
   439      is explicitly requested by the user, -1 if enabled by default.  */
       
   440   int pei386_auto_import;
       
   441 
       
   442   /* Non-zero if runtime relocs for DATA items with non-zero addends
       
   443      in pei386 DLLs should be generated.  Set to 1 if this feature
       
   444      is explicitly requested by the user, -1 if enabled by default.  */
       
   445   int pei386_runtime_pseudo_reloc;
       
   446 
       
   447   /* How many spare .dynamic DT_NULL entries should be added?  */
       
   448   unsigned int spare_dynamic_tags;
       
   449 
       
   450   /* May be used to set DT_FLAGS for ELF. */
       
   451   bfd_vma flags;
       
   452 
       
   453   /* May be used to set DT_FLAGS_1 for ELF. */
       
   454   bfd_vma flags_1;
       
   455 
       
   456   /* Start and end of RELRO region.  */
       
   457   bfd_vma relro_start, relro_end;
       
   458 
       
   459   /* List of symbols should be dynamic.  */
       
   460   struct bfd_elf_dynamic_list *dynamic_list;
       
   461 };
       
   462 
       
   463 /* This structures holds a set of callback functions.  These are called
       
   464    by the BFD linker routines.  Except for the info functions, the first
       
   465    argument to each callback function is the bfd_link_info structure
       
   466    being used and each function returns a boolean value.  If the
       
   467    function returns FALSE, then the BFD function which called it should
       
   468    return with a failure indication.  */
       
   469 
       
   470 struct bfd_link_callbacks
       
   471 {
       
   472   /* A function which is called when an object is added from an
       
   473      archive.  ABFD is the archive element being added.  NAME is the
       
   474      name of the symbol which caused the archive element to be pulled
       
   475      in.  */
       
   476   bfd_boolean (*add_archive_element)
       
   477     (struct bfd_link_info *, bfd *abfd, const char *name);
       
   478   /* A function which is called when a symbol is found with multiple
       
   479      definitions.  NAME is the symbol which is defined multiple times.
       
   480      OBFD is the old BFD, OSEC is the old section, OVAL is the old
       
   481      value, NBFD is the new BFD, NSEC is the new section, and NVAL is
       
   482      the new value.  OBFD may be NULL.  OSEC and NSEC may be
       
   483      bfd_com_section or bfd_ind_section.  */
       
   484   bfd_boolean (*multiple_definition)
       
   485     (struct bfd_link_info *, const char *name,
       
   486      bfd *obfd, asection *osec, bfd_vma oval,
       
   487      bfd *nbfd, asection *nsec, bfd_vma nval);
       
   488   /* A function which is called when a common symbol is defined
       
   489      multiple times.  NAME is the symbol appearing multiple times.
       
   490      OBFD is the BFD of the existing symbol; it may be NULL if this is
       
   491      not known.  OTYPE is the type of the existing symbol, which may
       
   492      be bfd_link_hash_defined, bfd_link_hash_defweak,
       
   493      bfd_link_hash_common, or bfd_link_hash_indirect.  If OTYPE is
       
   494      bfd_link_hash_common, OSIZE is the size of the existing symbol.
       
   495      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
       
   496      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
       
   497      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
       
   498      is the size of the new symbol.  */
       
   499   bfd_boolean (*multiple_common)
       
   500     (struct bfd_link_info *, const char *name,
       
   501      bfd *obfd, enum bfd_link_hash_type otype, bfd_vma osize,
       
   502      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
       
   503   /* A function which is called to add a symbol to a set.  ENTRY is
       
   504      the link hash table entry for the set itself (e.g.,
       
   505      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
       
   506      the set when generating a relocatable file, and is also used to
       
   507      get the size of the entry when generating an executable file.
       
   508      ABFD, SEC and VALUE identify the value to add to the set.  */
       
   509   bfd_boolean (*add_to_set)
       
   510     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
       
   511      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
       
   512   /* A function which is called when the name of a g++ constructor or
       
   513      destructor is found.  This is only called by some object file
       
   514      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
       
   515      destructor.  This will use BFD_RELOC_CTOR when generating a
       
   516      relocatable file.  NAME is the name of the symbol found.  ABFD,
       
   517      SECTION and VALUE are the value of the symbol.  */
       
   518   bfd_boolean (*constructor)
       
   519     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
       
   520      bfd *abfd, asection *sec, bfd_vma value);
       
   521   /* A function which is called to issue a linker warning.  For
       
   522      example, this is called when there is a reference to a warning
       
   523      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
       
   524      of the symbol which triggered the warning; it may be NULL if
       
   525      there is none.  ABFD, SECTION and ADDRESS identify the location
       
   526      which trigerred the warning; either ABFD or SECTION or both may
       
   527      be NULL if the location is not known.  */
       
   528   bfd_boolean (*warning)
       
   529     (struct bfd_link_info *, const char *warning, const char *symbol,
       
   530      bfd *abfd, asection *section, bfd_vma address);
       
   531   /* A function which is called when a relocation is attempted against
       
   532      an undefined symbol.  NAME is the symbol which is undefined.
       
   533      ABFD, SECTION and ADDRESS identify the location from which the
       
   534      reference is made. FATAL indicates whether an undefined symbol is
       
   535      a fatal error or not. In some cases SECTION may be NULL.  */
       
   536   bfd_boolean (*undefined_symbol)
       
   537     (struct bfd_link_info *, const char *name, bfd *abfd,
       
   538      asection *section, bfd_vma address, bfd_boolean fatal);
       
   539   /* A function which is called when a reloc overflow occurs. ENTRY is
       
   540      the link hash table entry for the symbol the reloc is against.
       
   541      NAME is the name of the local symbol or section the reloc is
       
   542      against, RELOC_NAME is the name of the relocation, and ADDEND is
       
   543      any addend that is used.  ABFD, SECTION and ADDRESS identify the
       
   544      location at which the overflow occurs; if this is the result of a
       
   545      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
       
   546      ABFD will be NULL.  */
       
   547   bfd_boolean (*reloc_overflow)
       
   548     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
       
   549      const char *name, const char *reloc_name, bfd_vma addend,
       
   550      bfd *abfd, asection *section, bfd_vma address);
       
   551   /* A function which is called when a dangerous reloc is performed.
       
   552      MESSAGE is an appropriate message.
       
   553      ABFD, SECTION and ADDRESS identify the location at which the
       
   554      problem occurred; if this is the result of a
       
   555      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
       
   556      ABFD will be NULL.  */
       
   557   bfd_boolean (*reloc_dangerous)
       
   558     (struct bfd_link_info *, const char *message,
       
   559      bfd *abfd, asection *section, bfd_vma address);
       
   560   /* A function which is called when a reloc is found to be attached
       
   561      to a symbol which is not being written out.  NAME is the name of
       
   562      the symbol.  ABFD, SECTION and ADDRESS identify the location of
       
   563      the reloc; if this is the result of a
       
   564      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
       
   565      ABFD will be NULL.  */
       
   566   bfd_boolean (*unattached_reloc)
       
   567     (struct bfd_link_info *, const char *name,
       
   568      bfd *abfd, asection *section, bfd_vma address);
       
   569   /* A function which is called when a symbol in notice_hash is
       
   570      defined or referenced.  NAME is the symbol.  ABFD, SECTION and
       
   571      ADDRESS are the value of the symbol.  If SECTION is
       
   572      bfd_und_section, this is a reference.  */
       
   573   bfd_boolean (*notice)
       
   574     (struct bfd_link_info *, const char *name,
       
   575      bfd *abfd, asection *section, bfd_vma address);
       
   576   /* Error or warning link info message.  */
       
   577   void (*einfo)
       
   578     (const char *fmt, ...);
       
   579   /* General link info message.  */
       
   580   void (*info)
       
   581     (const char *fmt, ...);
       
   582   /* Message to be printed in linker map file.  */
       
   583   void (*minfo)
       
   584     (const char *fmt, ...);
       
   585   /* This callback provides a chance for users of the BFD library to
       
   586      override its decision about whether to place two adjacent sections
       
   587      into the same segment.  */
       
   588   bfd_boolean (*override_segment_assignment)
       
   589     (struct bfd_link_info *, bfd * abfd,
       
   590      asection * current_section, asection * previous_section,
       
   591      bfd_boolean new_segment);
       
   592 };
       
   593 
       
   594 /* The linker builds link_order structures which tell the code how to
       
   595    include input data in the output file.  */
       
   596 
       
   597 /* These are the types of link_order structures.  */
       
   598 
       
   599 enum bfd_link_order_type
       
   600 {
       
   601   bfd_undefined_link_order,	/* Undefined.  */
       
   602   bfd_indirect_link_order,	/* Built from a section.  */
       
   603   bfd_data_link_order,		/* Set to explicit data.  */
       
   604   bfd_section_reloc_link_order,	/* Relocate against a section.  */
       
   605   bfd_symbol_reloc_link_order	/* Relocate against a symbol.  */
       
   606 };
       
   607 
       
   608 /* This is the link_order structure itself.  These form a chain
       
   609    attached to the output section whose contents they are describing.  */
       
   610 
       
   611 struct bfd_link_order
       
   612 {
       
   613   /* Next link_order in chain.  */
       
   614   struct bfd_link_order *next;
       
   615   /* Type of link_order.  */
       
   616   enum bfd_link_order_type type;
       
   617   /* Offset within output section.  */
       
   618   bfd_vma offset;
       
   619   /* Size within output section.  */
       
   620   bfd_size_type size;
       
   621   /* Type specific information.  */
       
   622   union
       
   623     {
       
   624       struct
       
   625 	{
       
   626 	  /* Section to include.  If this is used, then
       
   627 	     section->output_section must be the section the
       
   628 	     link_order is attached to, section->output_offset must
       
   629 	     equal the link_order offset field, and section->size
       
   630 	     must equal the link_order size field.  Maybe these
       
   631 	     restrictions should be relaxed someday.  */
       
   632 	  asection *section;
       
   633 	} indirect;
       
   634       struct
       
   635 	{
       
   636 	  /* Size of contents, or zero when contents size == size
       
   637 	     within output section.
       
   638 	     A non-zero value allows filling of the output section
       
   639 	     with an arbitrary repeated pattern.  */
       
   640 	  unsigned int size;
       
   641 	  /* Data to put into file.  */
       
   642 	  bfd_byte *contents;
       
   643 	} data;
       
   644       struct
       
   645 	{
       
   646 	  /* Description of reloc to generate.  Used for
       
   647 	     bfd_section_reloc_link_order and
       
   648 	     bfd_symbol_reloc_link_order.  */
       
   649 	  struct bfd_link_order_reloc *p;
       
   650 	} reloc;
       
   651     } u;
       
   652 };
       
   653 
       
   654 /* A linker order of type bfd_section_reloc_link_order or
       
   655    bfd_symbol_reloc_link_order means to create a reloc against a
       
   656    section or symbol, respectively.  This is used to implement -Ur to
       
   657    generate relocs for the constructor tables.  The
       
   658    bfd_link_order_reloc structure describes the reloc that BFD should
       
   659    create.  It is similar to a arelent, but I didn't use arelent
       
   660    because the linker does not know anything about most symbols, and
       
   661    any asymbol structure it creates will be partially meaningless.
       
   662    This information could logically be in the bfd_link_order struct,
       
   663    but I didn't want to waste the space since these types of relocs
       
   664    are relatively rare.  */
       
   665 
       
   666 struct bfd_link_order_reloc
       
   667 {
       
   668   /* Reloc type.  */
       
   669   bfd_reloc_code_real_type reloc;
       
   670 
       
   671   union
       
   672     {
       
   673       /* For type bfd_section_reloc_link_order, this is the section
       
   674 	 the reloc should be against.  This must be a section in the
       
   675 	 output BFD, not any of the input BFDs.  */
       
   676       asection *section;
       
   677       /* For type bfd_symbol_reloc_link_order, this is the name of the
       
   678 	 symbol the reloc should be against.  */
       
   679       const char *name;
       
   680     } u;
       
   681 
       
   682   /* Addend to use.  The object file should contain zero.  The BFD
       
   683      backend is responsible for filling in the contents of the object
       
   684      file correctly.  For some object file formats (e.g., COFF) the
       
   685      addend must be stored into in the object file, and for some
       
   686      (e.g., SPARC a.out) it is kept in the reloc.  */
       
   687   bfd_vma addend;
       
   688 };
       
   689 
       
   690 /* Allocate a new link_order for a section.  */
       
   691 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
       
   692 
       
   693 /* These structures are used to describe version information for the
       
   694    ELF linker.  These structures could be manipulated entirely inside
       
   695    BFD, but it would be a pain.  Instead, the regular linker sets up
       
   696    these structures, and then passes them into BFD.  */
       
   697 
       
   698 /* Glob pattern for a version.  */
       
   699 
       
   700 struct bfd_elf_version_expr
       
   701 {
       
   702   /* Next glob pattern for this version.  */
       
   703   struct bfd_elf_version_expr *next;
       
   704   /* Glob pattern.  */
       
   705   const char *pattern;
       
   706   /* NULL for a glob pattern, otherwise a straight symbol.  */
       
   707   const char *symbol;
       
   708   /* Defined by ".symver".  */
       
   709   unsigned int symver : 1;
       
   710   /* Defined by version script.  */
       
   711   unsigned int script : 1;
       
   712   /* Pattern type.  */
       
   713 #define BFD_ELF_VERSION_C_TYPE		1
       
   714 #define BFD_ELF_VERSION_CXX_TYPE	2
       
   715 #define BFD_ELF_VERSION_JAVA_TYPE	4
       
   716   unsigned int mask : 3;
       
   717 };
       
   718 
       
   719 struct bfd_elf_version_expr_head
       
   720 {
       
   721   /* List of all patterns, both wildcards and non-wildcards.  */
       
   722   struct bfd_elf_version_expr *list;
       
   723   /* Hash table for non-wildcards.  */
       
   724   void *htab;
       
   725   /* Remaining patterns.  */
       
   726   struct bfd_elf_version_expr *remaining;
       
   727   /* What kind of pattern types are present in list (bitmask).  */
       
   728   unsigned int mask;
       
   729 };
       
   730 
       
   731 /* Version dependencies.  */
       
   732 
       
   733 struct bfd_elf_version_deps
       
   734 {
       
   735   /* Next dependency for this version.  */
       
   736   struct bfd_elf_version_deps *next;
       
   737   /* The version which this version depends upon.  */
       
   738   struct bfd_elf_version_tree *version_needed;
       
   739 };
       
   740 
       
   741 /* A node in the version tree.  */
       
   742 
       
   743 struct bfd_elf_version_tree
       
   744 {
       
   745   /* Next version.  */
       
   746   struct bfd_elf_version_tree *next;
       
   747   /* Name of this version.  */
       
   748   const char *name;
       
   749   /* Version number.  */
       
   750   unsigned int vernum;
       
   751   /* Regular expressions for global symbols in this version.  */
       
   752   struct bfd_elf_version_expr_head globals;
       
   753   /* Regular expressions for local symbols in this version.  */
       
   754   struct bfd_elf_version_expr_head locals;
       
   755   /* List of versions which this version depends upon.  */
       
   756   struct bfd_elf_version_deps *deps;
       
   757   /* Index of the version name.  This is used within BFD.  */
       
   758   unsigned int name_indx;
       
   759   /* Whether this version tree was used.  This is used within BFD.  */
       
   760   int used;
       
   761   /* Matching hook.  */
       
   762   struct bfd_elf_version_expr *(*match)
       
   763     (struct bfd_elf_version_expr_head *head,
       
   764      struct bfd_elf_version_expr *prev, const char *sym);
       
   765 };
       
   766 
       
   767 struct bfd_elf_dynamic_list
       
   768 {
       
   769   struct bfd_elf_version_expr_head head;
       
   770   struct bfd_elf_version_expr *(*match)
       
   771     (struct bfd_elf_version_expr_head *head,
       
   772      struct bfd_elf_version_expr *prev, const char *sym);
       
   773 };
       
   774 
       
   775 #endif