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      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 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
     21 
     22 #ifndef BFDLINK_H
     23 #define BFDLINK_H
     24 
     25 /* Which symbols to strip during a link.  */
     26 enum bfd_link_strip
     27 {
     28   strip_none,		/* Don't strip any symbols.  */
     29   strip_debugger,	/* Strip debugging symbols.  */
     30   strip_some,		/* keep_hash is the list of symbols to keep.  */
     31   strip_all		/* Strip all symbols.  */
     32 };
     33 
     34 /* Which local symbols to discard during a link.  This is irrelevant
     35    if strip_all is used.  */
     36 enum bfd_link_discard
     37 {
     38   discard_sec_merge,	/* Discard local temporary symbols in SEC_MERGE
     39 			   sections.  */
     40   discard_none,		/* Don't discard any locals.  */
     41   discard_l,		/* Discard local temporary symbols.  */
     42   discard_all		/* Discard all locals.  */
     43 };
     44 
     45 /* Describes the type of hash table entry structure being used.
     46    Different hash table structure have different fields and so
     47    support different linking features.  */
     48 enum bfd_link_hash_table_type
     49   {
     50     bfd_link_generic_hash_table,
     51     bfd_link_elf_hash_table
     52   };
     53 
     54 /* 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.
    214    There are four possibilities which are enumerated below:  */
    215 enum report_method
    216 {
    217   /* This is the initial value when then link_info structure is created.
    218      It allows the various stages of the linker to determine whether they
    219      allowed to set the value.  */
    220   RM_NOT_YET_SET = 0,
    221   RM_IGNORE,
    222   RM_GENERATE_WARNING,
    223   RM_GENERATE_ERROR
    224 };
    225 
    226 struct bfd_elf_dynamic_list;
    227 
    228 /* This structure holds all the information needed to communicate
    229    between BFD and the linker when doing a link.  */
    230 
    231 struct bfd_link_info
    232 {
    233   /* TRUE if BFD should generate a relocatable object file.  */
    234   unsigned int relocatable: 1;
    235 
    236   /* TRUE if BFD should generate relocation information in the final
    237      executable.  */
    238   unsigned int emitrelocations: 1;
    239 
    240   /* TRUE if BFD should generate a "task linked" object file,
    241      similar to relocatable but also with globals converted to
    242      statics.  */
    243   unsigned int task_link: 1;
    244 
    245   /* TRUE if BFD should generate a shared object.  */
    246   unsigned int shared: 1;
    247 
    248   /* TRUE if BFD should pre-bind symbols in a shared object.  */
    249   unsigned int symbolic: 1;
    250 
    251   /* TRUE if BFD should export all symbols in the dynamic symbol table
    252      of an executable, rather than only those used.  */
    253   unsigned int export_dynamic: 1;
    254 
    255   /* TRUE if shared objects should be linked directly, not shared.  */
    256   unsigned int static_link: 1;
    257 
    258   /* TRUE if the output file should be in a traditional format.  This
    259      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
    260      on the output file, but may be checked when reading the input
    261      files.  */
    262   unsigned int traditional_format: 1;
    263 
    264   /* TRUE if we want to produced optimized output files.  This might
    265      need much more time and therefore must be explicitly selected.  */
    266   unsigned int optimize: 1;
    267 
    268   /* TRUE if ok to have multiple definition.  */
    269   unsigned int allow_multiple_definition: 1;
    270 
    271   /* TRUE if ok to have version with no definition.  */
    272   unsigned int allow_undefined_version: 1;
    273 
    274   /* TRUE if a default symbol version should be created and used for
    275      exported symbols.  */
    276   unsigned int create_default_symver: 1;
    277 
    278   /* TRUE if a default symbol version should be created and used for
    279      imported symbols.  */
    280   unsigned int default_imported_symver: 1;
    281 
    282   /* TRUE if symbols should be retained in memory, FALSE if they
    283      should be freed and reread.  */
    284   unsigned int keep_memory: 1;
    285 
    286   /* TRUE if every symbol should be reported back via the notice
    287      callback.  */
    288   unsigned int notice_all: 1;
    289 
    290   /* TRUE if executable should not contain copy relocs.
    291      Setting this true may result in a non-sharable text segment.  */
    292   unsigned int nocopyreloc: 1;
    293 
    294   /* TRUE if the new ELF dynamic tags are enabled. */
    295   unsigned int new_dtags: 1;
    296 
    297   /* TRUE if non-PLT relocs should be merged into one reloc section
    298      and sorted so that relocs against the same symbol come together.  */
    299   unsigned int combreloc: 1;
    300 
    301   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
    302      should be created.  */
    303   unsigned int eh_frame_hdr: 1;
    304 
    305   /* TRUE if global symbols in discarded sections should be stripped.  */
    306   unsigned int strip_discarded: 1;
    307 
    308   /* TRUE if generating a position independent executable.  */
    309   unsigned int pie: 1;
    310 
    311   /* TRUE if generating an executable, position independent or not.  */
    312   unsigned int executable : 1;
    313 
    314   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
    315      flags.  */
    316   unsigned int execstack: 1;
    317 
    318   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
    319      flags.  */
    320   unsigned int noexecstack: 1;
    321 
    322   /* TRUE if PT_GNU_RELRO segment should be created.  */
    323   unsigned int relro: 1;
    324 
    325   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
    326   unsigned int warn_shared_textrel: 1;
    327 
    328   /* TRUE if unreferenced sections should be removed.  */
    329   unsigned int gc_sections: 1;
    330 
    331   /* TRUE if user shoudl be informed of removed unreferenced sections.  */
    332   unsigned int print_gc_sections: 1;
    333 
    334   /* TRUE if .hash section should be created.  */
    335   unsigned int emit_hash: 1;
    336 
    337   /* TRUE if .gnu.hash section should be created.  */
    338   unsigned int emit_gnu_hash: 1;
    339 
    340   /* If TRUE reduce memory overheads, at the expense of speed. This will
    341      cause map file generation to use an O(N^2) algorithm and disable
    342      caching ELF symbol buffer.  */
    343   unsigned int reduce_memory_overheads: 1;
    344 
    345   /* What to do with unresolved symbols in an object file.
    346      When producing executables the default is GENERATE_ERROR.
    347      When producing shared libraries the default is IGNORE.  The
    348      assumption with shared libraries is that the reference will be
    349      resolved at load/execution time.  */
    350   enum report_method unresolved_syms_in_objects;
    351 
    352   /* What to do with unresolved symbols in a shared library.
    353      The same defaults apply.  */
    354   enum report_method unresolved_syms_in_shared_libs;
    355 
    356   /* Which symbols to strip.  */
    357   enum bfd_link_strip strip;
    358 
    359   /* Which local symbols to discard.  */
    360   enum bfd_link_discard discard;
    361 
    362   /* Criteria for skipping symbols when detemining
    363      whether to include an object from an archive. */
    364   enum bfd_link_common_skip_ar_aymbols common_skip_ar_aymbols;
    365 
    366   /* Char that may appear as the first char of a symbol, but should be
    367      skipped (like symbol_leading_char) when looking up symbols in
    368      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
    369   char wrap_char;
    370 
    371   /* Function callbacks.  */
    372   const struct bfd_link_callbacks *callbacks;
    373 
    374   /* Hash table handled by BFD.  */
    375   struct bfd_link_hash_table *hash;
    376 
    377   /* Hash table of symbols to keep.  This is NULL unless strip is
    378      strip_some.  */
    379   struct bfd_hash_table *keep_hash;
    380 
    381   /* Hash table of symbols to report back via the notice callback.  If
    382      this is NULL, and notice_all is FALSE, then no symbols are
    383      reported back.  */
    384   struct bfd_hash_table *notice_hash;
    385 
    386   /* Hash table of symbols which are being wrapped (the --wrap linker
    387      option).  If this is NULL, no symbols are being wrapped.  */
    388   struct bfd_hash_table *wrap_hash;
    389 
    390   /* The list of input BFD's involved in the link.  These are chained
    391      together via the link_next field.  */
    392   bfd *input_bfds;
    393 
    394   /* If a symbol should be created for each input BFD, this is section
    395      where those symbols should be placed.  It must be a section in
    396      the output BFD.  It may be NULL, in which case no such symbols
    397      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
    398      linker command language.  */
    399   asection *create_object_symbols_section;
    400 
    401   /* List of global symbol names that are starting points for marking
    402      sections against garbage collection.  */
    403   struct bfd_sym_chain *gc_sym_list;
    404 
    405   /* If a base output file is wanted, then this points to it */
    406   void *base_file;
    407 
    408   /* The function to call when the executable or shared object is
    409      loaded.  */
    410   const char *init_function;
    411 
    412   /* The function to call when the executable or shared object is
    413      unloaded.  */
    414   const char *fini_function;
    415 
    416   /* Number of relaxation passes.  Usually only one relaxation pass
    417      is needed.  But a backend can have as many relaxation passes as
    418      necessary.  During bfd_relax_section call, it is set to the
    419      current pass, starting from 0.  */
    420   int relax_pass;
    421 
    422   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
    423      should be generated/linked against.  Set to 1 if this feature
    424      is explicitly requested by the user, -1 if enabled by default.  */
    425   int pei386_auto_import;
    426 
    427   /* Non-zero if runtime relocs for DATA items with non-zero addends
    428      in pei386 DLLs should be generated.  Set to 1 if this feature
    429      is explicitly requested by the user, -1 if enabled by default.  */
    430   int pei386_runtime_pseudo_reloc;
    431 
    432   /* How many spare .dynamic DT_NULL entries should be added?  */
    433   unsigned int spare_dynamic_tags;
    434 
    435   /* May be used to set DT_FLAGS for ELF. */
    436   bfd_vma flags;
    437 
    438   /* May be used to set DT_FLAGS_1 for ELF. */
    439   bfd_vma flags_1;
    440 
    441   /* Start and end of RELRO region.  */
    442   bfd_vma relro_start, relro_end;
    443 
    444   /* List of symbols should be dynamic.  */
    445   struct bfd_elf_dynamic_list *dynamic;
    446 };
    447 
    448 /* This structures holds a set of callback functions.  These are
    449    called by the BFD linker routines.  Except for einfo, the first
    450    argument to each callback function is the bfd_link_info structure
    451    being used and each function returns a boolean value.  If the
    452    function returns FALSE, then the BFD function which called it should
    453    return with a failure indication.  */
    454 
    455 struct bfd_link_callbacks
    456 {
    457   /* A function which is called when an object is added from an
    458      archive.  ABFD is the archive element being added.  NAME is the
    459      name of the symbol which caused the archive element to be pulled
    460      in.  */
    461   bfd_boolean (*add_archive_element)
    462     (struct bfd_link_info *, bfd *abfd, const char *name);
    463   /* A function which is called when a symbol is found with multiple
    464      definitions.  NAME is the symbol which is defined multiple times.
    465      OBFD is the old BFD, OSEC is the old section, OVAL is the old
    466      value, NBFD is the new BFD, NSEC is the new section, and NVAL is
    467      the new value.  OBFD may be NULL.  OSEC and NSEC may be
    468      bfd_com_section or bfd_ind_section.  */
    469   bfd_boolean (*multiple_definition)
    470     (struct bfd_link_info *, const char *name,
    471      bfd *obfd, asection *osec, bfd_vma oval,
    472      bfd *nbfd, asection *nsec, bfd_vma nval);
    473   /* A function which is called when a common symbol is defined
    474      multiple times.  NAME is the symbol appearing multiple times.
    475      OBFD is the BFD of the existing symbol; it may be NULL if this is
    476      not known.  OTYPE is the type of the existing symbol, which may
    477      be bfd_link_hash_defined, bfd_link_hash_defweak,
    478      bfd_link_hash_common, or bfd_link_hash_indirect.  If OTYPE is
    479      bfd_link_hash_common, OSIZE is the size of the existing symbol.
    480      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
    481      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
    482      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
    483      is the size of the new symbol.  */
    484   bfd_boolean (*multiple_common)
    485     (struct bfd_link_info *, const char *name,
    486      bfd *obfd, enum bfd_link_hash_type otype, bfd_vma osize,
    487      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
    488   /* A function which is called to add a symbol to a set.  ENTRY is
    489      the link hash table entry for the set itself (e.g.,
    490      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
    491      the set when generating a relocatable file, and is also used to
    492      get the size of the entry when generating an executable file.
    493      ABFD, SEC and VALUE identify the value to add to the set.  */
    494   bfd_boolean (*add_to_set)
    495     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
    496      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
    497   /* A function which is called when the name of a g++ constructor or
    498      destructor is found.  This is only called by some object file
    499      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
    500      destructor.  This will use BFD_RELOC_CTOR when generating a
    501      relocatable file.  NAME is the name of the symbol found.  ABFD,
    502      SECTION and VALUE are the value of the symbol.  */
    503   bfd_boolean (*constructor)
    504     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
    505      bfd *abfd, asection *sec, bfd_vma value);
    506   /* A function which is called to issue a linker warning.  For
    507      example, this is called when there is a reference to a warning
    508      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
    509      of the symbol which triggered the warning; it may be NULL if
    510      there is none.  ABFD, SECTION and ADDRESS identify the location
    511      which trigerred the warning; either ABFD or SECTION or both may
    512      be NULL if the location is not known.  */
    513   bfd_boolean (*warning)
    514     (struct bfd_link_info *, const char *warning, const char *symbol,
    515      bfd *abfd, asection *section, bfd_vma address);
    516   /* A function which is called when a relocation is attempted against
    517      an undefined symbol.  NAME is the symbol which is undefined.
    518      ABFD, SECTION and ADDRESS identify the location from which the
    519      reference is made. FATAL indicates whether an undefined symbol is
    520      a fatal error or not. In some cases SECTION may be NULL.  */
    521   bfd_boolean (*undefined_symbol)
    522     (struct bfd_link_info *, const char *name, bfd *abfd,
    523      asection *section, bfd_vma address, bfd_boolean fatal);
    524   /* A function which is called when a reloc overflow occurs. ENTRY is
    525      the link hash table entry for the symbol the reloc is against.
    526      NAME is the name of the local symbol or section the reloc is
    527      against, RELOC_NAME is the name of the relocation, and ADDEND is
    528      any addend that is used.  ABFD, SECTION and ADDRESS identify the
    529      location at which the overflow occurs; if this is the result of a
    530      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
    531      ABFD will be NULL.  */
    532   bfd_boolean (*reloc_overflow)
    533     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
    534      const char *name, const char *reloc_name, bfd_vma addend,
    535      bfd *abfd, asection *section, bfd_vma address);
    536   /* A function which is called when a dangerous reloc is performed.
    537      MESSAGE is an appropriate message.
    538      ABFD, SECTION and ADDRESS identify the location at which the
    539      problem occurred; if this is the result of a
    540      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
    541      ABFD will be NULL.  */
    542   bfd_boolean (*reloc_dangerous)
    543     (struct bfd_link_info *, const char *message,
    544      bfd *abfd, asection *section, bfd_vma address);
    545   /* A function which is called when a reloc is found to be attached
    546      to a symbol which is not being written out.  NAME is the name of
    547      the symbol.  ABFD, SECTION and ADDRESS identify the location of
    548      the reloc; if this is the result of a
    549      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
    550      ABFD will be NULL.  */
    551   bfd_boolean (*unattached_reloc)
    552     (struct bfd_link_info *, const char *name,
    553      bfd *abfd, asection *section, bfd_vma address);
    554   /* A function which is called when a symbol in notice_hash is
    555      defined or referenced.  NAME is the symbol.  ABFD, SECTION and
    556      ADDRESS are the value of the symbol.  If SECTION is
    557      bfd_und_section, this is a reference.  */
    558   bfd_boolean (*notice)
    559     (struct bfd_link_info *, const char *name,
    560      bfd *abfd, asection *section, bfd_vma address);
    561   /* General link info message.  */
    562   void (*einfo)
    563     (const char *fmt, ...);
    564 };
    565 
    566 /* The linker builds link_order structures which tell the code how to
    568    include input data in the output file.  */
    569 
    570 /* These are the types of link_order structures.  */
    571 
    572 enum bfd_link_order_type
    573 {
    574   bfd_undefined_link_order,	/* Undefined.  */
    575   bfd_indirect_link_order,	/* Built from a section.  */
    576   bfd_data_link_order,		/* Set to explicit data.  */
    577   bfd_section_reloc_link_order,	/* Relocate against a section.  */
    578   bfd_symbol_reloc_link_order	/* Relocate against a symbol.  */
    579 };
    580 
    581 /* This is the link_order structure itself.  These form a chain
    582    attached to the output section whose contents they are describing.  */
    583 
    584 struct bfd_link_order
    585 {
    586   /* Next link_order in chain.  */
    587   struct bfd_link_order *next;
    588   /* Type of link_order.  */
    589   enum bfd_link_order_type type;
    590   /* Offset within output section.  */
    591   bfd_vma offset;
    592   /* Size within output section.  */
    593   bfd_size_type size;
    594   /* Type specific information.  */
    595   union
    596     {
    597       struct
    598 	{
    599 	  /* Section to include.  If this is used, then
    600 	     section->output_section must be the section the
    601 	     link_order is attached to, section->output_offset must
    602 	     equal the link_order offset field, and section->size
    603 	     must equal the link_order size field.  Maybe these
    604 	     restrictions should be relaxed someday.  */
    605 	  asection *section;
    606 	} indirect;
    607       struct
    608 	{
    609 	  /* Size of contents, or zero when contents size == size
    610 	     within output section.
    611 	     A non-zero value allows filling of the output section
    612 	     with an arbitrary repeated pattern.  */
    613 	  unsigned int size;
    614 	  /* Data to put into file.  */
    615 	  bfd_byte *contents;
    616 	} data;
    617       struct
    618 	{
    619 	  /* Description of reloc to generate.  Used for
    620 	     bfd_section_reloc_link_order and
    621 	     bfd_symbol_reloc_link_order.  */
    622 	  struct bfd_link_order_reloc *p;
    623 	} reloc;
    624     } u;
    625 };
    626 
    627 /* A linker order of type bfd_section_reloc_link_order or
    628    bfd_symbol_reloc_link_order means to create a reloc against a
    629    section or symbol, respectively.  This is used to implement -Ur to
    630    generate relocs for the constructor tables.  The
    631    bfd_link_order_reloc structure describes the reloc that BFD should
    632    create.  It is similar to a arelent, but I didn't use arelent
    633    because the linker does not know anything about most symbols, and
    634    any asymbol structure it creates will be partially meaningless.
    635    This information could logically be in the bfd_link_order struct,
    636    but I didn't want to waste the space since these types of relocs
    637    are relatively rare.  */
    638 
    639 struct bfd_link_order_reloc
    640 {
    641   /* Reloc type.  */
    642   bfd_reloc_code_real_type reloc;
    643 
    644   union
    645     {
    646       /* For type bfd_section_reloc_link_order, this is the section
    647 	 the reloc should be against.  This must be a section in the
    648 	 output BFD, not any of the input BFDs.  */
    649       asection *section;
    650       /* For type bfd_symbol_reloc_link_order, this is the name of the
    651 	 symbol the reloc should be against.  */
    652       const char *name;
    653     } u;
    654 
    655   /* Addend to use.  The object file should contain zero.  The BFD
    656      backend is responsible for filling in the contents of the object
    657      file correctly.  For some object file formats (e.g., COFF) the
    658      addend must be stored into in the object file, and for some
    659      (e.g., SPARC a.out) it is kept in the reloc.  */
    660   bfd_vma addend;
    661 };
    662 
    663 /* Allocate a new link_order for a section.  */
    664 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
    665 
    666 /* These structures are used to describe version information for the
    667    ELF linker.  These structures could be manipulated entirely inside
    668    BFD, but it would be a pain.  Instead, the regular linker sets up
    669    these structures, and then passes them into BFD.  */
    670 
    671 /* Glob pattern for a version.  */
    672 
    673 struct bfd_elf_version_expr
    674 {
    675   /* Next glob pattern for this version.  */
    676   struct bfd_elf_version_expr *next;
    677   /* Glob pattern.  */
    678   const char *pattern;
    679   /* NULL for a glob pattern, otherwise a straight symbol.  */
    680   const char *symbol;
    681   /* Defined by ".symver".  */
    682   unsigned int symver : 1;
    683   /* Defined by version script.  */
    684   unsigned int script : 1;
    685   /* Pattern type.  */
    686 #define BFD_ELF_VERSION_C_TYPE		1
    687 #define BFD_ELF_VERSION_CXX_TYPE	2
    688 #define BFD_ELF_VERSION_JAVA_TYPE	4
    689   unsigned int mask : 3;
    690 };
    691 
    692 struct bfd_elf_version_expr_head
    693 {
    694   /* List of all patterns, both wildcards and non-wildcards.  */
    695   struct bfd_elf_version_expr *list;
    696   /* Hash table for non-wildcards.  */
    697   void *htab;
    698   /* Remaining patterns.  */
    699   struct bfd_elf_version_expr *remaining;
    700   /* What kind of pattern types are present in list (bitmask).  */
    701   unsigned int mask;
    702 };
    703 
    704 /* Version dependencies.  */
    705 
    706 struct bfd_elf_version_deps
    707 {
    708   /* Next dependency for this version.  */
    709   struct bfd_elf_version_deps *next;
    710   /* The version which this version depends upon.  */
    711   struct bfd_elf_version_tree *version_needed;
    712 };
    713 
    714 /* A node in the version tree.  */
    715 
    716 struct bfd_elf_version_tree
    717 {
    718   /* Next version.  */
    719   struct bfd_elf_version_tree *next;
    720   /* Name of this version.  */
    721   const char *name;
    722   /* Version number.  */
    723   unsigned int vernum;
    724   /* Regular expressions for global symbols in this version.  */
    725   struct bfd_elf_version_expr_head globals;
    726   /* Regular expressions for local symbols in this version.  */
    727   struct bfd_elf_version_expr_head locals;
    728   /* List of versions which this version depends upon.  */
    729   struct bfd_elf_version_deps *deps;
    730   /* Index of the version name.  This is used within BFD.  */
    731   unsigned int name_indx;
    732   /* Whether this version tree was used.  This is used within BFD.  */
    733   int used;
    734   /* Matching hook.  */
    735   struct bfd_elf_version_expr *(*match)
    736     (struct bfd_elf_version_expr_head *head,
    737      struct bfd_elf_version_expr *prev, const char *sym);
    738 };
    739 
    740 struct bfd_elf_dynamic_list
    741 {
    742   struct bfd_elf_version_expr_head head;
    743   struct bfd_elf_version_expr *(*match)
    744     (struct bfd_elf_version_expr_head *head,
    745      struct bfd_elf_version_expr *prev, const char *sym);
    746 };
    747 
    748 #endif
    749