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  1. /* bfdlink.h -- header file for BFD link routines
  2.    Copyright (C) 1993-2015 Free Software Foundation, Inc.
  3.    Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
  4.  
  5.    This file is part of BFD, the Binary File Descriptor library.
  6.  
  7.    This program is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3 of the License, or
  10.    (at your option) any later version.
  11.  
  12.    This program is distributed in the hope that it will be useful,
  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.    GNU General Public License for more details.
  16.  
  17.    You should have received a copy of the GNU General Public License
  18.    along with this program; if not, write to the Free Software
  19.    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20.    MA 02110-1301, USA.  */
  21.  
  22. #ifndef BFDLINK_H
  23. #define BFDLINK_H
  24.  
  25. /* Which symbols to strip during a link.  */
  26. enum bfd_link_strip
  27. {
  28.   strip_none,           /* Don't strip any symbols.  */
  29.   strip_debugger,       /* Strip debugging symbols.  */
  30.   strip_some,           /* keep_hash is the list of symbols to keep.  */
  31.   strip_all             /* Strip all symbols.  */
  32. };
  33.  
  34. /* Which local symbols to discard during a link.  This is irrelevant
  35.    if strip_all is used.  */
  36. enum bfd_link_discard
  37. {
  38.   discard_sec_merge,    /* Discard local temporary symbols in SEC_MERGE
  39.                            sections.  */
  40.   discard_none,         /* Don't discard any locals.  */
  41.   discard_l,            /* Discard local temporary symbols.  */
  42.   discard_all           /* Discard all locals.  */
  43. };
  44.  
  45. /* Describes the type of hash table entry structure being used.
  46.    Different hash table structure have different fields and so
  47.    support different linking features.  */
  48. enum bfd_link_hash_table_type
  49.   {
  50.     bfd_link_generic_hash_table,
  51.     bfd_link_elf_hash_table
  52.   };
  53. /* These are the possible types of an entry in the BFD link hash
  54.    table.  */
  55.  
  56. enum bfd_link_hash_type
  57. {
  58.   bfd_link_hash_new,            /* Symbol is new.  */
  59.   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  60.   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  61.   bfd_link_hash_defined,        /* Symbol is defined.  */
  62.   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  63.   bfd_link_hash_common,         /* Symbol is common.  */
  64.   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  65.   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  66. };
  67.  
  68. enum bfd_link_common_skip_ar_symbols
  69. {
  70.   bfd_link_common_skip_none,
  71.   bfd_link_common_skip_text,
  72.   bfd_link_common_skip_data,
  73.   bfd_link_common_skip_all
  74. };
  75.  
  76. struct bfd_link_hash_common_entry
  77.   {
  78.     unsigned int alignment_power;       /* Alignment.  */
  79.     asection *section;          /* Symbol section.  */
  80.   };
  81.  
  82. /* The linking routines use a hash table which uses this structure for
  83.    its elements.  */
  84.  
  85. struct bfd_link_hash_entry
  86. {
  87.   /* Base hash table entry structure.  */
  88.   struct bfd_hash_entry root;
  89.  
  90.   /* Type of this entry.  */
  91.   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
  92.  
  93.   /* Symbol is referenced in a normal object file, as distict from a LTO
  94.      IR object file.  */
  95.   unsigned int non_ir_ref : 1;
  96.  
  97.   /* Symbol is a built-in define.  These will be overridden by PROVIDE
  98.      in a linker script.  */
  99.   unsigned int linker_def : 1;
  100.  
  101.   /* A union of information depending upon the type.  */
  102.   union
  103.     {
  104.       /* Nothing is kept for bfd_hash_new.  */
  105.       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
  106.       struct
  107.         {
  108.           /* Undefined and common symbols are kept in a linked list through
  109.              this field.  This field is present in all of the union element
  110.              so that we don't need to remove entries from the list when we
  111.              change their type.  Removing entries would either require the
  112.              list to be doubly linked, which would waste more memory, or
  113.              require a traversal.  When an undefined or common symbol is
  114.              created, it should be added to this list, the head of which is in
  115.              the link hash table itself.  As symbols are defined, they need
  116.              not be removed from the list; anything which reads the list must
  117.              doublecheck the symbol type.
  118.  
  119.              Weak symbols are not kept on this list.
  120.  
  121.              Defined and defweak symbols use this field as a reference marker.
  122.              If the field is not NULL, or this structure is the tail of the
  123.              undefined symbol list, the symbol has been referenced.  If the
  124.              symbol is undefined and becomes defined, this field will
  125.              automatically be non-NULL since the symbol will have been on the
  126.              undefined symbol list.  */
  127.           struct bfd_link_hash_entry *next;
  128.           bfd *abfd;            /* BFD symbol was found in.  */
  129.         } undef;
  130.       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
  131.       struct
  132.         {
  133.           struct bfd_link_hash_entry *next;
  134.           asection *section;    /* Symbol section.  */
  135.           bfd_vma value;        /* Symbol value.  */
  136.         } def;
  137.       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
  138.       struct
  139.         {
  140.           struct bfd_link_hash_entry *next;
  141.           struct bfd_link_hash_entry *link;     /* Real symbol.  */
  142.           const char *warning;  /* Warning (bfd_link_hash_warning only).  */
  143.         } i;
  144.       /* bfd_link_hash_common.  */
  145.       struct
  146.         {
  147.           struct bfd_link_hash_entry *next;
  148.           /* The linker needs to know three things about common
  149.              symbols: the size, the alignment, and the section in
  150.              which the symbol should be placed.  We store the size
  151.              here, and we allocate a small structure to hold the
  152.              section and the alignment.  The alignment is stored as a
  153.              power of two.  We don't store all the information
  154.              directly because we don't want to increase the size of
  155.              the union; this structure is a major space user in the
  156.              linker.  */
  157.           struct bfd_link_hash_common_entry *p;
  158.           bfd_size_type size;   /* Common symbol size.  */
  159.         } c;
  160.     } u;
  161. };
  162.  
  163. /* This is the link hash table.  It is a derived class of
  164.    bfd_hash_table.  */
  165.  
  166. struct bfd_link_hash_table
  167. {
  168.   /* The hash table itself.  */
  169.   struct bfd_hash_table table;
  170.   /* A linked list of undefined and common symbols, linked through the
  171.      next field in the bfd_link_hash_entry structure.  */
  172.   struct bfd_link_hash_entry *undefs;
  173.   /* Entries are added to the tail of the undefs list.  */
  174.   struct bfd_link_hash_entry *undefs_tail;
  175.   /* Function to free the hash table on closing BFD.  */
  176.   void (*hash_table_free) (bfd *);
  177.   /* The type of the link hash table.  */
  178.   enum bfd_link_hash_table_type type;
  179. };
  180.  
  181. /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
  182.    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
  183.    the real symbol.  */
  184. extern struct bfd_link_hash_entry *bfd_link_hash_lookup
  185.   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
  186.    bfd_boolean copy, bfd_boolean follow);
  187.  
  188. /* Look up an entry in the main linker hash table if the symbol might
  189.    be wrapped.  This should only be used for references to an
  190.    undefined symbol, not for definitions of a symbol.  */
  191.  
  192. extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
  193.   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
  194.    bfd_boolean, bfd_boolean);
  195.  
  196. /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
  197.    and the remainder is found in wrap_hash, return the real symbol.  */
  198.  
  199. extern struct bfd_link_hash_entry *unwrap_hash_lookup
  200.   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
  201.  
  202. /* Traverse a link hash table.  */
  203. extern void bfd_link_hash_traverse
  204.   (struct bfd_link_hash_table *,
  205.     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
  206.     void *);
  207.  
  208. /* Add an entry to the undefs list.  */
  209. extern void bfd_link_add_undef
  210.   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
  211.  
  212. /* Remove symbols from the undefs list that don't belong there.  */
  213. extern void bfd_link_repair_undef_list
  214.   (struct bfd_link_hash_table *table);
  215.  
  216. /* Read symbols and cache symbol pointer array in outsymbols.  */
  217. extern bfd_boolean bfd_generic_link_read_symbols (bfd *);
  218.  
  219. struct bfd_sym_chain
  220. {
  221.   struct bfd_sym_chain *next;
  222.   const char *name;
  223. };
  224. /* How to handle unresolved symbols.
  225.    There are four possibilities which are enumerated below:  */
  226. enum report_method
  227. {
  228.   /* This is the initial value when then link_info structure is created.
  229.      It allows the various stages of the linker to determine whether they
  230.      allowed to set the value.  */
  231.   RM_NOT_YET_SET = 0,
  232.   RM_IGNORE,
  233.   RM_GENERATE_WARNING,
  234.   RM_GENERATE_ERROR
  235. };
  236.  
  237. typedef enum {with_flags, without_flags} flag_type;
  238.  
  239. /* A section flag list.  */
  240. struct flag_info_list
  241. {
  242.   flag_type with;
  243.   const char *name;
  244.   bfd_boolean valid;
  245.   struct flag_info_list *next;
  246. };
  247.  
  248. /* Section flag info.  */
  249. struct flag_info
  250. {
  251.   flagword only_with_flags;
  252.   flagword not_with_flags;
  253.   struct flag_info_list *flag_list;
  254.   bfd_boolean flags_initialized;
  255. };
  256.  
  257. struct bfd_elf_dynamic_list;
  258. struct bfd_elf_version_tree;
  259.  
  260. /* Types of output.  */
  261.  
  262. enum output_type
  263. {
  264.   type_pde,
  265.   type_pie,
  266.   type_relocatable,
  267.   type_dll,
  268. };
  269.  
  270. #define bfd_link_pde(info)         ((info)->type == type_pde)
  271. #define bfd_link_dll(info)         ((info)->type == type_dll)
  272. #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
  273. #define bfd_link_pie(info)         ((info)->type == type_pie)
  274. #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
  275. #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
  276.  
  277. /* This structure holds all the information needed to communicate
  278.    between BFD and the linker when doing a link.  */
  279.  
  280. struct bfd_link_info
  281. {
  282.   /* Output type.  */
  283.   ENUM_BITFIELD (output_type) type : 2;
  284.  
  285.   /* TRUE if BFD should pre-bind symbols in a shared object.  */
  286.   unsigned int symbolic: 1;
  287.  
  288.   /* TRUE if executable should not contain copy relocs.
  289.      Setting this true may result in a non-sharable text segment.  */
  290.   unsigned int nocopyreloc: 1;
  291.  
  292.   /* TRUE if BFD should export all symbols in the dynamic symbol table
  293.      of an executable, rather than only those used.  */
  294.   unsigned int export_dynamic: 1;
  295.  
  296.   /* TRUE if a default symbol version should be created and used for
  297.      exported symbols.  */
  298.   unsigned int create_default_symver: 1;
  299.  
  300.   /* TRUE if unreferenced sections should be removed.  */
  301.   unsigned int gc_sections: 1;
  302.  
  303.   /* TRUE if every symbol should be reported back via the notice
  304.      callback.  */
  305.   unsigned int notice_all: 1;
  306.  
  307.   /* TRUE if the LTO plugin is active.  */
  308.   unsigned int lto_plugin_active: 1;
  309.  
  310.   /* TRUE if global symbols in discarded sections should be stripped.  */
  311.   unsigned int strip_discarded: 1;
  312.  
  313.   /* TRUE if all data symbols should be dynamic.  */
  314.   unsigned int dynamic_data: 1;
  315.  
  316.   /* Which symbols to strip.  */
  317.   ENUM_BITFIELD (bfd_link_strip) strip : 2;
  318.  
  319.   /* Which local symbols to discard.  */
  320.   ENUM_BITFIELD (bfd_link_discard) discard : 2;
  321.  
  322.   /* Criteria for skipping symbols when determining
  323.      whether to include an object from an archive. */
  324.   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
  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_BITFIELD (report_method) unresolved_syms_in_objects : 2;
  332.  
  333.   /* What to do with unresolved symbols in a shared library.
  334.      The same defaults apply.  */
  335.   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
  336.  
  337.   /* TRUE if shared objects should be linked directly, not shared.  */
  338.   unsigned int static_link: 1;
  339.  
  340.   /* TRUE if symbols should be retained in memory, FALSE if they
  341.      should be freed and reread.  */
  342.   unsigned int keep_memory: 1;
  343.  
  344.   /* TRUE if BFD should generate relocation information in the final
  345.      executable.  */
  346.   unsigned int emitrelocations: 1;
  347.  
  348.   /* TRUE if PT_GNU_RELRO segment should be created.  */
  349.   unsigned int relro: 1;
  350.  
  351.   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
  352.      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
  353.   unsigned int eh_frame_hdr_type: 2;
  354.  
  355.   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
  356.   unsigned int warn_shared_textrel: 1;
  357.  
  358.   /* TRUE if we should error when adding a DT_TEXTREL.  */
  359.   unsigned int error_textrel: 1;
  360.  
  361.   /* TRUE if .hash section should be created.  */
  362.   unsigned int emit_hash: 1;
  363.  
  364.   /* TRUE if .gnu.hash section should be created.  */
  365.   unsigned int emit_gnu_hash: 1;
  366.  
  367.   /* If TRUE reduce memory overheads, at the expense of speed. This will
  368.      cause map file generation to use an O(N^2) algorithm and disable
  369.      caching ELF symbol buffer.  */
  370.   unsigned int reduce_memory_overheads: 1;
  371.  
  372.   /* TRUE if the output file should be in a traditional format.  This
  373.      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
  374.      on the output file, but may be checked when reading the input
  375.      files.  */
  376.   unsigned int traditional_format: 1;
  377.  
  378.   /* TRUE if non-PLT relocs should be merged into one reloc section
  379.      and sorted so that relocs against the same symbol come together.  */
  380.   unsigned int combreloc: 1;
  381.  
  382.   /* TRUE if a default symbol version should be created and used for
  383.      imported symbols.  */
  384.   unsigned int default_imported_symver: 1;
  385.  
  386.   /* TRUE if the new ELF dynamic tags are enabled. */
  387.   unsigned int new_dtags: 1;
  388.  
  389.   /* FALSE if .eh_frame unwind info should be generated for PLT and other
  390.      linker created sections, TRUE if it should be omitted.  */
  391.   unsigned int no_ld_generated_unwind_info: 1;
  392.  
  393.   /* TRUE if BFD should generate a "task linked" object file,
  394.      similar to relocatable but also with globals converted to
  395.      statics.  */
  396.   unsigned int task_link: 1;
  397.  
  398.   /* TRUE if ok to have multiple definition.  */
  399.   unsigned int allow_multiple_definition: 1;
  400.  
  401.   /* TRUE if ok to have version with no definition.  */
  402.   unsigned int allow_undefined_version: 1;
  403.  
  404.   /* TRUE if some symbols have to be dynamic, controlled by
  405.      --dynamic-list command line options.  */
  406.   unsigned int dynamic: 1;
  407.  
  408.   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
  409.      flags.  */
  410.   unsigned int execstack: 1;
  411.  
  412.   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
  413.      flags.  */
  414.   unsigned int noexecstack: 1;
  415.  
  416.   /* TRUE if we want to produced optimized output files.  This might
  417.      need much more time and therefore must be explicitly selected.  */
  418.   unsigned int optimize: 1;
  419.  
  420.   /* TRUE if user should be informed of removed unreferenced sections.  */
  421.   unsigned int print_gc_sections: 1;
  422.  
  423.   /* TRUE if we should warn alternate ELF machine code.  */
  424.   unsigned int warn_alternate_em: 1;
  425.  
  426.   /* TRUE if the linker script contained an explicit PHDRS command.  */
  427.   unsigned int user_phdrs: 1;
  428.  
  429.   /* TRUE if BND prefix in PLT entries is always generated.  */
  430.   unsigned int bndplt: 1;
  431.  
  432.   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
  433.   unsigned int nointerp: 1;
  434.  
  435.   /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction.  */
  436.   unsigned int call_nop_as_suffix : 1;
  437.  
  438.   /* The 1-byte NOP for x86 call instruction.  */
  439.   char call_nop_byte;
  440.  
  441.   /* Char that may appear as the first char of a symbol, but should be
  442.      skipped (like symbol_leading_char) when looking up symbols in
  443.      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
  444.   char wrap_char;
  445.  
  446.   /* Separator between archive and filename in linker script filespecs.  */
  447.   char path_separator;
  448.  
  449.   /* Compress DWARF debug sections.  */
  450.   enum compressed_debug_section_type compress_debug;
  451.  
  452.   /* Default stack size.  Zero means default (often zero itself), -1
  453.      means explicitly zero-sized.  */
  454.   bfd_signed_vma stacksize;
  455.  
  456.   /* Enable or disable target specific optimizations.
  457.  
  458.      Not all targets have optimizations to enable.
  459.  
  460.      Normally these optimizations are disabled by default but some targets
  461.      prefer to enable them by default.  So this field is a tri-state variable.
  462.      The values are:
  463.      
  464.      zero: Enable the optimizations (either from --relax being specified on
  465.        the command line or the backend's before_allocation emulation function.
  466.        
  467.      positive: The user has requested that these optimizations be disabled.
  468.        (Via the --no-relax command line option).
  469.  
  470.      negative: The optimizations are disabled.  (Set when initializing the
  471.        args_type structure in ldmain.c:main.  */
  472.   signed int disable_target_specific_optimizations;
  473.  
  474.   /* Function callbacks.  */
  475.   const struct bfd_link_callbacks *callbacks;
  476.  
  477.   /* Hash table handled by BFD.  */
  478.   struct bfd_link_hash_table *hash;
  479.  
  480.   /* Hash table of symbols to keep.  This is NULL unless strip is
  481.      strip_some.  */
  482.   struct bfd_hash_table *keep_hash;
  483.  
  484.   /* Hash table of symbols to report back via the notice callback.  If
  485.      this is NULL, and notice_all is FALSE, then no symbols are
  486.      reported back.  */
  487.   struct bfd_hash_table *notice_hash;
  488.  
  489.   /* Hash table of symbols which are being wrapped (the --wrap linker
  490.      option).  If this is NULL, no symbols are being wrapped.  */
  491.   struct bfd_hash_table *wrap_hash;
  492.  
  493.   /* Hash table of symbols which may be left unresolved during
  494.      a link.  If this is NULL, no symbols can be left unresolved.  */
  495.   struct bfd_hash_table *ignore_hash;
  496.  
  497.   /* The output BFD.  */
  498.   bfd *output_bfd;
  499.  
  500.   /* The list of input BFD's involved in the link.  These are chained
  501.      together via the link.next field.  */
  502.   bfd *input_bfds;
  503.   bfd **input_bfds_tail;
  504.  
  505.   /* If a symbol should be created for each input BFD, this is section
  506.      where those symbols should be placed.  It must be a section in
  507.      the output BFD.  It may be NULL, in which case no such symbols
  508.      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
  509.      linker command language.  */
  510.   asection *create_object_symbols_section;
  511.  
  512.   /* List of global symbol names that are starting points for marking
  513.      sections against garbage collection.  */
  514.   struct bfd_sym_chain *gc_sym_list;
  515.  
  516.   /* If a base output file is wanted, then this points to it */
  517.   void *base_file;
  518.  
  519.   /* The function to call when the executable or shared object is
  520.      loaded.  */
  521.   const char *init_function;
  522.  
  523.   /* The function to call when the executable or shared object is
  524.      unloaded.  */
  525.   const char *fini_function;
  526.  
  527.   /* Number of relaxation passes.  Usually only one relaxation pass
  528.      is needed.  But a backend can have as many relaxation passes as
  529.      necessary.  During bfd_relax_section call, it is set to the
  530.      current pass, starting from 0.  */
  531.   int relax_pass;
  532.  
  533.   /* Number of relaxation trips.  This number is incremented every
  534.      time the relaxation pass is restarted due to a previous
  535.      relaxation returning true in *AGAIN.  */
  536.   int relax_trip;
  537.  
  538.   /* > 0 to treat protected data defined in the shared library as
  539.      reference external.  0 to treat it as internal.  -1 to let
  540.      backend to decide.  */
  541.   int extern_protected_data;
  542.  
  543.   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
  544.      should be generated/linked against.  Set to 1 if this feature
  545.      is explicitly requested by the user, -1 if enabled by default.  */
  546.   int pei386_auto_import;
  547.  
  548.   /* Non-zero if runtime relocs for DATA items with non-zero addends
  549.      in pei386 DLLs should be generated.  Set to 1 if this feature
  550.      is explicitly requested by the user, -1 if enabled by default.  */
  551.   int pei386_runtime_pseudo_reloc;
  552.  
  553.   /* How many spare .dynamic DT_NULL entries should be added?  */
  554.   unsigned int spare_dynamic_tags;
  555.  
  556.   /* May be used to set DT_FLAGS for ELF. */
  557.   bfd_vma flags;
  558.  
  559.   /* May be used to set DT_FLAGS_1 for ELF. */
  560.   bfd_vma flags_1;
  561.  
  562.   /* Start and end of RELRO region.  */
  563.   bfd_vma relro_start, relro_end;
  564.  
  565.   /* List of symbols should be dynamic.  */
  566.   struct bfd_elf_dynamic_list *dynamic_list;
  567.  
  568.   /* The version information.  */
  569.   struct bfd_elf_version_tree *version_info;
  570. };
  571.  
  572. /* This structures holds a set of callback functions.  These are called
  573.    by the BFD linker routines.  Except for the info functions, the first
  574.    argument to each callback function is the bfd_link_info structure
  575.    being used and each function returns a boolean value.  If the
  576.    function returns FALSE, then the BFD function which called it should
  577.    return with a failure indication.  */
  578.  
  579. struct bfd_link_callbacks
  580. {
  581.   /* A function which is called when an object is added from an
  582.      archive.  ABFD is the archive element being added.  NAME is the
  583.      name of the symbol which caused the archive element to be pulled
  584.      in.  This function may set *SUBSBFD to point to an alternative
  585.      BFD from which symbols should in fact be added in place of the
  586.      original BFD's symbols.  */
  587.   bfd_boolean (*add_archive_element)
  588.     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
  589.   /* A function which is called when a symbol is found with multiple
  590.      definitions.  H is the symbol which is defined multiple times.
  591.      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
  592.      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
  593.   bfd_boolean (*multiple_definition)
  594.     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
  595.      bfd *nbfd, asection *nsec, bfd_vma nval);
  596.   /* A function which is called when a common symbol is defined
  597.      multiple times.  H is the symbol appearing multiple times.
  598.      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
  599.      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
  600.      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
  601.      is the size of the new symbol.  */
  602.   bfd_boolean (*multiple_common)
  603.     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
  604.      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
  605.   /* A function which is called to add a symbol to a set.  ENTRY is
  606.      the link hash table entry for the set itself (e.g.,
  607.      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
  608.      the set when generating a relocatable file, and is also used to
  609.      get the size of the entry when generating an executable file.
  610.      ABFD, SEC and VALUE identify the value to add to the set.  */
  611.   bfd_boolean (*add_to_set)
  612.     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
  613.      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
  614.   /* A function which is called when the name of a g++ constructor or
  615.      destructor is found.  This is only called by some object file
  616.      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
  617.      destructor.  This will use BFD_RELOC_CTOR when generating a
  618.      relocatable file.  NAME is the name of the symbol found.  ABFD,
  619.      SECTION and VALUE are the value of the symbol.  */
  620.   bfd_boolean (*constructor)
  621.     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
  622.      bfd *abfd, asection *sec, bfd_vma value);
  623.   /* A function which is called to issue a linker warning.  For
  624.      example, this is called when there is a reference to a warning
  625.      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
  626.      of the symbol which triggered the warning; it may be NULL if
  627.      there is none.  ABFD, SECTION and ADDRESS identify the location
  628.      which trigerred the warning; either ABFD or SECTION or both may
  629.      be NULL if the location is not known.  */
  630.   bfd_boolean (*warning)
  631.     (struct bfd_link_info *, const char *warning, const char *symbol,
  632.      bfd *abfd, asection *section, bfd_vma address);
  633.   /* A function which is called when a relocation is attempted against
  634.      an undefined symbol.  NAME is the symbol which is undefined.
  635.      ABFD, SECTION and ADDRESS identify the location from which the
  636.      reference is made. IS_FATAL indicates whether an undefined symbol is
  637.      a fatal error or not. In some cases SECTION may be NULL.  */
  638.   bfd_boolean (*undefined_symbol)
  639.     (struct bfd_link_info *, const char *name, bfd *abfd,
  640.      asection *section, bfd_vma address, bfd_boolean is_fatal);
  641.   /* A function which is called when a reloc overflow occurs. ENTRY is
  642.      the link hash table entry for the symbol the reloc is against.
  643.      NAME is the name of the local symbol or section the reloc is
  644.      against, RELOC_NAME is the name of the relocation, and ADDEND is
  645.      any addend that is used.  ABFD, SECTION and ADDRESS identify the
  646.      location at which the overflow occurs; if this is the result of a
  647.      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
  648.      ABFD will be NULL.  */
  649.   bfd_boolean (*reloc_overflow)
  650.     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
  651.      const char *name, const char *reloc_name, bfd_vma addend,
  652.      bfd *abfd, asection *section, bfd_vma address);
  653.   /* A function which is called when a dangerous reloc is performed.
  654.      MESSAGE is an appropriate message.
  655.      ABFD, SECTION and ADDRESS identify the location at which the
  656.      problem occurred; if this is the result of a
  657.      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
  658.      ABFD will be NULL.  */
  659.   bfd_boolean (*reloc_dangerous)
  660.     (struct bfd_link_info *, const char *message,
  661.      bfd *abfd, asection *section, bfd_vma address);
  662.   /* A function which is called when a reloc is found to be attached
  663.      to a symbol which is not being written out.  NAME is the name of
  664.      the symbol.  ABFD, SECTION and ADDRESS identify the location of
  665.      the reloc; if this is the result of a
  666.      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
  667.      ABFD will be NULL.  */
  668.   bfd_boolean (*unattached_reloc)
  669.     (struct bfd_link_info *, const char *name,
  670.      bfd *abfd, asection *section, bfd_vma address);
  671.   /* A function which is called when a symbol in notice_hash is
  672.      defined or referenced.  H is the symbol, INH the indirect symbol
  673.      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
  674.      the symbol.  If SECTION is bfd_und_section, this is a reference.
  675.      FLAGS are the symbol BSF_* flags.  */
  676.   bfd_boolean (*notice)
  677.     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
  678.      struct bfd_link_hash_entry *inh,
  679.      bfd *abfd, asection *section, bfd_vma address, flagword flags);
  680.   /* Error or warning link info message.  */
  681.   void (*einfo)
  682.     (const char *fmt, ...);
  683.   /* General link info message.  */
  684.   void (*info)
  685.     (const char *fmt, ...);
  686.   /* Message to be printed in linker map file.  */
  687.   void (*minfo)
  688.     (const char *fmt, ...);
  689.   /* This callback provides a chance for users of the BFD library to
  690.      override its decision about whether to place two adjacent sections
  691.      into the same segment.  */
  692.   bfd_boolean (*override_segment_assignment)
  693.     (struct bfd_link_info *, bfd * abfd,
  694.      asection * current_section, asection * previous_section,
  695.      bfd_boolean new_segment);
  696. };
  697. /* The linker builds link_order structures which tell the code how to
  698.    include input data in the output file.  */
  699.  
  700. /* These are the types of link_order structures.  */
  701.  
  702. enum bfd_link_order_type
  703. {
  704.   bfd_undefined_link_order,     /* Undefined.  */
  705.   bfd_indirect_link_order,      /* Built from a section.  */
  706.   bfd_data_link_order,          /* Set to explicit data.  */
  707.   bfd_section_reloc_link_order, /* Relocate against a section.  */
  708.   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
  709. };
  710.  
  711. /* This is the link_order structure itself.  These form a chain
  712.    attached to the output section whose contents they are describing.  */
  713.  
  714. struct bfd_link_order
  715. {
  716.   /* Next link_order in chain.  */
  717.   struct bfd_link_order *next;
  718.   /* Type of link_order.  */
  719.   enum bfd_link_order_type type;
  720.   /* Offset within output section.  */
  721.   bfd_vma offset;
  722.   /* Size within output section.  */
  723.   bfd_size_type size;
  724.   /* Type specific information.  */
  725.   union
  726.     {
  727.       struct
  728.         {
  729.           /* Section to include.  If this is used, then
  730.              section->output_section must be the section the
  731.              link_order is attached to, section->output_offset must
  732.              equal the link_order offset field, and section->size
  733.              must equal the link_order size field.  Maybe these
  734.              restrictions should be relaxed someday.  */
  735.           asection *section;
  736.         } indirect;
  737.       struct
  738.         {
  739.           /* Size of contents, or zero when contents should be filled by
  740.              the architecture-dependent fill function.
  741.              A non-zero value allows filling of the output section
  742.              with an arbitrary repeated pattern.  */
  743.           unsigned int size;
  744.           /* Data to put into file.  */
  745.           bfd_byte *contents;
  746.         } data;
  747.       struct
  748.         {
  749.           /* Description of reloc to generate.  Used for
  750.              bfd_section_reloc_link_order and
  751.              bfd_symbol_reloc_link_order.  */
  752.           struct bfd_link_order_reloc *p;
  753.         } reloc;
  754.     } u;
  755. };
  756.  
  757. /* A linker order of type bfd_section_reloc_link_order or
  758.    bfd_symbol_reloc_link_order means to create a reloc against a
  759.    section or symbol, respectively.  This is used to implement -Ur to
  760.    generate relocs for the constructor tables.  The
  761.    bfd_link_order_reloc structure describes the reloc that BFD should
  762.    create.  It is similar to a arelent, but I didn't use arelent
  763.    because the linker does not know anything about most symbols, and
  764.    any asymbol structure it creates will be partially meaningless.
  765.    This information could logically be in the bfd_link_order struct,
  766.    but I didn't want to waste the space since these types of relocs
  767.    are relatively rare.  */
  768.  
  769. struct bfd_link_order_reloc
  770. {
  771.   /* Reloc type.  */
  772.   bfd_reloc_code_real_type reloc;
  773.  
  774.   union
  775.     {
  776.       /* For type bfd_section_reloc_link_order, this is the section
  777.          the reloc should be against.  This must be a section in the
  778.          output BFD, not any of the input BFDs.  */
  779.       asection *section;
  780.       /* For type bfd_symbol_reloc_link_order, this is the name of the
  781.          symbol the reloc should be against.  */
  782.       const char *name;
  783.     } u;
  784.  
  785.   /* Addend to use.  The object file should contain zero.  The BFD
  786.      backend is responsible for filling in the contents of the object
  787.      file correctly.  For some object file formats (e.g., COFF) the
  788.      addend must be stored into in the object file, and for some
  789.      (e.g., SPARC a.out) it is kept in the reloc.  */
  790.   bfd_vma addend;
  791. };
  792.  
  793. /* Allocate a new link_order for a section.  */
  794. extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
  795.  
  796. /* These structures are used to describe version information for the
  797.    ELF linker.  These structures could be manipulated entirely inside
  798.    BFD, but it would be a pain.  Instead, the regular linker sets up
  799.    these structures, and then passes them into BFD.  */
  800.  
  801. /* Glob pattern for a version.  */
  802.  
  803. struct bfd_elf_version_expr
  804. {
  805.   /* Next glob pattern for this version.  */
  806.   struct bfd_elf_version_expr *next;
  807.   /* Glob pattern.  */
  808.   const char *pattern;
  809.   /* Set if pattern is not a glob.  */
  810.   unsigned int literal : 1;
  811.   /* Defined by ".symver".  */
  812.   unsigned int symver : 1;
  813.   /* Defined by version script.  */
  814.   unsigned int script : 1;
  815.   /* Pattern type.  */
  816. #define BFD_ELF_VERSION_C_TYPE          1
  817. #define BFD_ELF_VERSION_CXX_TYPE        2
  818. #define BFD_ELF_VERSION_JAVA_TYPE       4
  819.   unsigned int mask : 3;
  820. };
  821.  
  822. struct bfd_elf_version_expr_head
  823. {
  824.   /* List of all patterns, both wildcards and non-wildcards.  */
  825.   struct bfd_elf_version_expr *list;
  826.   /* Hash table for non-wildcards.  */
  827.   void *htab;
  828.   /* Remaining patterns.  */
  829.   struct bfd_elf_version_expr *remaining;
  830.   /* What kind of pattern types are present in list (bitmask).  */
  831.   unsigned int mask;
  832. };
  833.  
  834. /* Version dependencies.  */
  835.  
  836. struct bfd_elf_version_deps
  837. {
  838.   /* Next dependency for this version.  */
  839.   struct bfd_elf_version_deps *next;
  840.   /* The version which this version depends upon.  */
  841.   struct bfd_elf_version_tree *version_needed;
  842. };
  843.  
  844. /* A node in the version tree.  */
  845.  
  846. struct bfd_elf_version_tree
  847. {
  848.   /* Next version.  */
  849.   struct bfd_elf_version_tree *next;
  850.   /* Name of this version.  */
  851.   const char *name;
  852.   /* Version number.  */
  853.   unsigned int vernum;
  854.   /* Regular expressions for global symbols in this version.  */
  855.   struct bfd_elf_version_expr_head globals;
  856.   /* Regular expressions for local symbols in this version.  */
  857.   struct bfd_elf_version_expr_head locals;
  858.   /* List of versions which this version depends upon.  */
  859.   struct bfd_elf_version_deps *deps;
  860.   /* Index of the version name.  This is used within BFD.  */
  861.   unsigned int name_indx;
  862.   /* Whether this version tree was used.  This is used within BFD.  */
  863.   int used;
  864.   /* Matching hook.  */
  865.   struct bfd_elf_version_expr *(*match)
  866.     (struct bfd_elf_version_expr_head *head,
  867.      struct bfd_elf_version_expr *prev, const char *sym);
  868. };
  869.  
  870. struct bfd_elf_dynamic_list
  871. {
  872.   struct bfd_elf_version_expr_head head;
  873.   struct bfd_elf_version_expr *(*match)
  874.     (struct bfd_elf_version_expr_head *head,
  875.      struct bfd_elf_version_expr *prev, const char *sym);
  876. };
  877.  
  878. #endif
  879.