xref: /openbsd-src/gnu/usr.bin/binutils-2.17/include/bfdlink.h (revision f2da64fbbbf1b03f09f390ab01267c93dfd77c4c)
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
55    table.  */
56 
57 enum bfd_link_hash_type
58 {
59   bfd_link_hash_new,		/* Symbol is new.  */
60   bfd_link_hash_undefined,	/* Symbol seen before, but undefined.  */
61   bfd_link_hash_undefweak,	/* Symbol is weak and undefined.  */
62   bfd_link_hash_defined,	/* Symbol is defined.  */
63   bfd_link_hash_defweak,	/* Symbol is weak and defined.  */
64   bfd_link_hash_common,		/* Symbol is common.  */
65   bfd_link_hash_indirect,	/* Symbol is an indirect link.  */
66   bfd_link_hash_warning		/* Like indirect, but warn if referenced.  */
67 };
68 
69 enum bfd_link_common_skip_ar_aymbols
70 {
71   bfd_link_common_skip_none,
72   bfd_link_common_skip_text,
73   bfd_link_common_skip_data,
74   bfd_link_common_skip_all
75 };
76 
77 /* The linking routines use a hash table which uses this structure for
78    its elements.  */
79 
80 struct bfd_link_hash_entry
81 {
82   /* Base hash table entry structure.  */
83   struct bfd_hash_entry root;
84 
85   /* Type of this entry.  */
86   enum bfd_link_hash_type type;
87 
88   /* A union of information depending upon the type.  */
89   union
90     {
91       /* Nothing is kept for bfd_hash_new.  */
92       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
93       struct
94 	{
95 	  /* Undefined and common symbols are kept in a linked list through
96 	     this field.  This field is present in all of the union element
97 	     so that we don't need to remove entries from the list when we
98 	     change their type.  Removing entries would either require the
99 	     list to be doubly linked, which would waste more memory, or
100 	     require a traversal.  When an undefined or common symbol is
101 	     created, it should be added to this list, the head of which is in
102 	     the link hash table itself.  As symbols are defined, they need
103 	     not be removed from the list; anything which reads the list must
104 	     doublecheck the symbol type.
105 
106 	     Weak symbols are not kept on this list.
107 
108 	     Defined and defweak symbols use this field as a reference marker.
109 	     If the field is not NULL, or this structure is the tail of the
110 	     undefined symbol list, the symbol has been referenced.  If the
111 	     symbol is undefined and becomes defined, this field will
112 	     automatically be non-NULL since the symbol will have been on the
113 	     undefined symbol list.  */
114 	  struct bfd_link_hash_entry *next;
115 	  bfd *abfd;		/* BFD symbol was found in.  */
116 	  bfd *weak;		/* BFD weak symbol was found in.  */
117 	} undef;
118       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
119       struct
120 	{
121 	  struct bfd_link_hash_entry *next;
122 	  asection *section;	/* Symbol section.  */
123 	  bfd_vma value;	/* Symbol value.  */
124 	} def;
125       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
126       struct
127 	{
128 	  struct bfd_link_hash_entry *next;
129 	  struct bfd_link_hash_entry *link;	/* Real symbol.  */
130 	  const char *warning;	/* Warning (bfd_link_hash_warning only).  */
131 	} i;
132       /* bfd_link_hash_common.  */
133       struct
134 	{
135 	  struct bfd_link_hash_entry *next;
136 	  /* The linker needs to know three things about common
137 	     symbols: the size, the alignment, and the section in
138 	     which the symbol should be placed.  We store the size
139 	     here, and we allocate a small structure to hold the
140 	     section and the alignment.  The alignment is stored as a
141 	     power of two.  We don't store all the information
142 	     directly because we don't want to increase the size of
143 	     the union; this structure is a major space user in the
144 	     linker.  */
145 	  struct bfd_link_hash_common_entry
146 	    {
147 	      unsigned int alignment_power;	/* Alignment.  */
148 	      asection *section;		/* Symbol section.  */
149 	    } *p;
150 	  bfd_size_type size;	/* Common symbol size.  */
151 	} c;
152     } u;
153 };
154 
155 /* This is the link hash table.  It is a derived class of
156    bfd_hash_table.  */
157 
158 struct bfd_link_hash_table
159 {
160   /* The hash table itself.  */
161   struct bfd_hash_table table;
162   /* The back end which created this hash table.  This indicates the
163      type of the entries in the hash table, which is sometimes
164      important information when linking object files of different
165      types together.  */
166   const bfd_target *creator;
167   /* A linked list of undefined and common symbols, linked through the
168      next field in the bfd_link_hash_entry structure.  */
169   struct bfd_link_hash_entry *undefs;
170   /* Entries are added to the tail of the undefs list.  */
171   struct bfd_link_hash_entry *undefs_tail;
172   /* The type of the link hash table.  */
173   enum bfd_link_hash_table_type type;
174 };
175 
176 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
177    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
178    the real symbol.  */
179 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
180   (struct bfd_link_hash_table *, const char *, bfd_boolean create,
181    bfd_boolean copy, bfd_boolean follow);
182 
183 /* Look up an entry in the main linker hash table if the symbol might
184    be wrapped.  This should only be used for references to an
185    undefined symbol, not for definitions of a symbol.  */
186 
187 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
188   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
189    bfd_boolean, bfd_boolean);
190 
191 /* Traverse a link hash table.  */
192 extern void bfd_link_hash_traverse
193   (struct bfd_link_hash_table *,
194     bfd_boolean (*) (struct bfd_link_hash_entry *, void *),
195     void *);
196 
197 /* Add an entry to the undefs list.  */
198 extern void bfd_link_add_undef
199   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
200 
201 /* Remove symbols from the undefs list that don't belong there.  */
202 extern void bfd_link_repair_undef_list
203   (struct bfd_link_hash_table *table);
204 
205 struct bfd_sym_chain
206 {
207   struct bfd_sym_chain *next;
208   const char *name;
209 };
210 
211 /* How to handle unresolved symbols.
212    There are four possibilities which are enumerated below:  */
213 enum report_method
214 {
215   /* This is the initial value when then link_info structure is created.
216      It allows the various stages of the linker to determine whether they
217      allowed to set the value.  */
218   RM_NOT_YET_SET = 0,
219   RM_IGNORE,
220   RM_GENERATE_WARNING,
221   RM_GENERATE_ERROR
222 };
223 
224 /* This structure holds all the information needed to communicate
225    between BFD and the linker when doing a link.  */
226 
227 struct bfd_link_info
228 {
229   /* TRUE if BFD should generate a relocatable object file.  */
230   unsigned int relocatable: 1;
231 
232   /* TRUE if BFD should generate relocation information in the final
233      executable.  */
234   unsigned int emitrelocations: 1;
235 
236   /* TRUE if BFD should generate a "task linked" object file,
237      similar to relocatable but also with globals converted to
238      statics.  */
239   unsigned int task_link: 1;
240 
241   /* TRUE if BFD should generate a shared object.  */
242   unsigned int shared: 1;
243 
244   /* TRUE if BFD should pre-bind symbols in a shared object.  */
245   unsigned int symbolic: 1;
246 
247   /* TRUE if BFD should export all symbols in the dynamic symbol table
248      of an executable, rather than only those used.  */
249   unsigned int export_dynamic: 1;
250 
251   /* TRUE if shared objects should be linked directly, not shared.  */
252   unsigned int static_link: 1;
253 
254   /* TRUE if the output file should be in a traditional format.  This
255      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
256      on the output file, but may be checked when reading the input
257      files.  */
258   unsigned int traditional_format: 1;
259 
260   /* TRUE if we want to produced optimized output files.  This might
261      need much more time and therefore must be explicitly selected.  */
262   unsigned int optimize: 1;
263 
264   /* TRUE if ok to have multiple definition.  */
265   unsigned int allow_multiple_definition: 1;
266 
267   /* TRUE if output program should be marked to request W^X permission */
268   unsigned int wxneeded: 1;
269 
270   /* TRUE if ok to have version with no definition.  */
271   unsigned int allow_undefined_version: 1;
272 
273   /* TRUE if ok to have text relocations.  */
274   unsigned int allow_textrel: 1;
275 
276   /* TRUE if a default symbol version should be created and used for
277      exported symbols.  */
278   unsigned int create_default_symver: 1;
279 
280   /* TRUE if a default symbol version should be created and used for
281      imported symbols.  */
282   unsigned int default_imported_symver: 1;
283 
284   /* TRUE if symbols should be retained in memory, FALSE if they
285      should be freed and reread.  */
286   unsigned int keep_memory: 1;
287 
288   /* TRUE if every symbol should be reported back via the notice
289      callback.  */
290   unsigned int notice_all: 1;
291 
292   /* TRUE if executable should not contain copy relocs.
293      Setting this true may result in a non-sharable text segment.  */
294   unsigned int nocopyreloc: 1;
295 
296   /* TRUE if the new ELF dynamic tags are enabled. */
297   unsigned int new_dtags: 1;
298 
299   /* TRUE if non-PLT relocs should be merged into one reloc section
300      and sorted so that relocs against the same symbol come together.  */
301   unsigned int combreloc: 1;
302 
303   /* TRUE if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
304      should be created.  */
305   unsigned int eh_frame_hdr: 1;
306 
307   /* TRUE if global symbols in discarded sections should be stripped.  */
308   unsigned int strip_discarded: 1;
309 
310   /* TRUE if generating a position independent executable.  */
311   unsigned int pie: 1;
312 
313   /* TRUE if generating an executable, position independent or not.  */
314   unsigned int executable : 1;
315 
316   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
317      flags.  */
318   unsigned int execstack: 1;
319 
320   /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
321      flags.  */
322   unsigned int noexecstack: 1;
323 
324   /* TRUE if PT_GNU_RELRO segment should be created.  */
325   unsigned int relro: 1;
326 
327   /* TRUE if we should warn when adding a DT_TEXTREL to a shared object.  */
328   unsigned int warn_shared_textrel: 1;
329 
330   /* TRUE if unreferenced sections should be removed.  */
331   unsigned int gc_sections: 1;
332 
333   /* If TRUE reduce memory overheads, at the expense of speed. This will
334      cause map file generation to use an O(N^2) algorithm and disable
335      caching ELF symbol buffer.  */
336   unsigned int reduce_memory_overheads: 1;
337 
338   /* What to do with unresolved symbols in an object file.
339      When producing executables the default is GENERATE_ERROR.
340      When producing shared libraries the default is IGNORE.  The
341      assumption with shared libraries is that the reference will be
342      resolved at load/execution time.  */
343   enum report_method unresolved_syms_in_objects;
344 
345   /* What to do with unresolved symbols in a shared library.
346      The same defaults apply.  */
347   enum report_method unresolved_syms_in_shared_libs;
348 
349   /* Which symbols to strip.  */
350   enum bfd_link_strip strip;
351 
352   /* Which local symbols to discard.  */
353   enum bfd_link_discard discard;
354 
355   /* Criteria for skipping symbols when detemining
356      whether to include an object from an archive. */
357   enum bfd_link_common_skip_ar_aymbols common_skip_ar_aymbols;
358 
359   /* Char that may appear as the first char of a symbol, but should be
360      skipped (like symbol_leading_char) when looking up symbols in
361      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
362   char wrap_char;
363 
364   /* Function callbacks.  */
365   const struct bfd_link_callbacks *callbacks;
366 
367   /* Hash table handled by BFD.  */
368   struct bfd_link_hash_table *hash;
369 
370   /* Hash table of symbols to keep.  This is NULL unless strip is
371      strip_some.  */
372   struct bfd_hash_table *keep_hash;
373 
374   /* Hash table of symbols to report back via the notice callback.  If
375      this is NULL, and notice_all is FALSE, then no symbols are
376      reported back.  */
377   struct bfd_hash_table *notice_hash;
378 
379   /* Hash table of symbols which are being wrapped (the --wrap linker
380      option).  If this is NULL, no symbols are being wrapped.  */
381   struct bfd_hash_table *wrap_hash;
382 
383   /* The list of input BFD's involved in the link.  These are chained
384      together via the link_next field.  */
385   bfd *input_bfds;
386 
387   /* If a symbol should be created for each input BFD, this is section
388      where those symbols should be placed.  It must be a section in
389      the output BFD.  It may be NULL, in which case no such symbols
390      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
391      linker command language.  */
392   asection *create_object_symbols_section;
393 
394   /* List of global symbol names that are starting points for marking
395      sections against garbage collection.  */
396   struct bfd_sym_chain *gc_sym_list;
397 
398   /* If a base output file is wanted, then this points to it */
399   void *base_file;
400 
401   /* The function to call when the executable or shared object is
402      loaded.  */
403   const char *init_function;
404 
405   /* The function to call when the executable or shared object is
406      unloaded.  */
407   const char *fini_function;
408 
409   /* Number of relaxation passes.  Usually only one relaxation pass
410      is needed.  But a backend can have as many relaxation passes as
411      necessary.  During bfd_relax_section call, it is set to the
412      current pass, starting from 0.  */
413   int relax_pass;
414 
415   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
416      should be generated/linked against.  Set to 1 if this feature
417      is explicitly requested by the user, -1 if enabled by default.  */
418   int pei386_auto_import;
419 
420   /* Non-zero if runtime relocs for DATA items with non-zero addends
421      in pei386 DLLs should be generated.  Set to 1 if this feature
422      is explicitly requested by the user, -1 if enabled by default.  */
423   int pei386_runtime_pseudo_reloc;
424 
425   /* How many spare .dynamic DT_NULL entries should be added?  */
426   unsigned int spare_dynamic_tags;
427 
428   /* May be used to set DT_FLAGS for ELF. */
429   bfd_vma flags;
430 
431   /* May be used to set DT_FLAGS_1 for ELF. */
432   bfd_vma flags_1;
433 
434   /* Start and end of RELRO region.  */
435   bfd_vma relro_start, relro_end;
436 };
437 
438 /* This structures holds a set of callback functions.  These are
439    called by the BFD linker routines.  Except for einfo, the first
440    argument to each callback function is the bfd_link_info structure
441    being used and each function returns a boolean value.  If the
442    function returns FALSE, then the BFD function which called it should
443    return with a failure indication.  */
444 
445 struct bfd_link_callbacks
446 {
447   /* A function which is called when an object is added from an
448      archive.  ABFD is the archive element being added.  NAME is the
449      name of the symbol which caused the archive element to be pulled
450      in.  */
451   bfd_boolean (*add_archive_element)
452     (struct bfd_link_info *, bfd *abfd, const char *name);
453   /* A function which is called when a symbol is found with multiple
454      definitions.  NAME is the symbol which is defined multiple times.
455      OBFD is the old BFD, OSEC is the old section, OVAL is the old
456      value, NBFD is the new BFD, NSEC is the new section, and NVAL is
457      the new value.  OBFD may be NULL.  OSEC and NSEC may be
458      bfd_com_section or bfd_ind_section.  */
459   bfd_boolean (*multiple_definition)
460     (struct bfd_link_info *, const char *name,
461      bfd *obfd, asection *osec, bfd_vma oval,
462      bfd *nbfd, asection *nsec, bfd_vma nval);
463   /* A function which is called when a common symbol is defined
464      multiple times.  NAME is the symbol appearing multiple times.
465      OBFD is the BFD of the existing symbol; it may be NULL if this is
466      not known.  OTYPE is the type of the existing symbol, which may
467      be bfd_link_hash_defined, bfd_link_hash_defweak,
468      bfd_link_hash_common, or bfd_link_hash_indirect.  If OTYPE is
469      bfd_link_hash_common, OSIZE is the size of the existing symbol.
470      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
471      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
472      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
473      is the size of the new symbol.  */
474   bfd_boolean (*multiple_common)
475     (struct bfd_link_info *, const char *name,
476      bfd *obfd, enum bfd_link_hash_type otype, bfd_vma osize,
477      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
478   /* A function which is called to add a symbol to a set.  ENTRY is
479      the link hash table entry for the set itself (e.g.,
480      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
481      the set when generating a relocatable file, and is also used to
482      get the size of the entry when generating an executable file.
483      ABFD, SEC and VALUE identify the value to add to the set.  */
484   bfd_boolean (*add_to_set)
485     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
486      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
487   /* A function which is called when the name of a g++ constructor or
488      destructor is found.  This is only called by some object file
489      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
490      destructor.  This will use BFD_RELOC_CTOR when generating a
491      relocatable file.  NAME is the name of the symbol found.  ABFD,
492      SECTION and VALUE are the value of the symbol.  */
493   bfd_boolean (*constructor)
494     (struct bfd_link_info *, bfd_boolean constructor, const char *name,
495      bfd *abfd, asection *sec, bfd_vma value);
496   /* A function which is called to issue a linker warning.  For
497      example, this is called when there is a reference to a warning
498      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
499      of the symbol which triggered the warning; it may be NULL if
500      there is none.  ABFD, SECTION and ADDRESS identify the location
501      which trigerred the warning; either ABFD or SECTION or both may
502      be NULL if the location is not known.  */
503   bfd_boolean (*warning)
504     (struct bfd_link_info *, const char *warning, const char *symbol,
505      bfd *abfd, asection *section, bfd_vma address);
506   /* A function which is called when a relocation is attempted against
507      an undefined symbol.  NAME is the symbol which is undefined.
508      ABFD, SECTION and ADDRESS identify the location from which the
509      reference is made. FATAL indicates whether an undefined symbol is
510      a fatal error or not. In some cases SECTION may be NULL.  */
511   bfd_boolean (*undefined_symbol)
512     (struct bfd_link_info *, const char *name, bfd *abfd,
513      asection *section, bfd_vma address, bfd_boolean fatal);
514   /* A function which is called when a reloc overflow occurs. ENTRY is
515      the link hash table entry for the symbol the reloc is against.
516      NAME is the name of the local symbol or section the reloc is
517      against, RELOC_NAME is the name of the relocation, and ADDEND is
518      any addend that is used.  ABFD, SECTION and ADDRESS identify the
519      location at which the overflow occurs; if this is the result of a
520      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
521      ABFD will be NULL.  */
522   bfd_boolean (*reloc_overflow)
523     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
524      const char *name, const char *reloc_name, bfd_vma addend,
525      bfd *abfd, asection *section, bfd_vma address);
526   /* A function which is called when a dangerous reloc is performed.
527      MESSAGE is an appropriate message.
528      ABFD, SECTION and ADDRESS identify the location at which the
529      problem occurred; 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_dangerous)
533     (struct bfd_link_info *, const char *message,
534      bfd *abfd, asection *section, bfd_vma address);
535   /* A function which is called when a reloc is found to be attached
536      to a symbol which is not being written out.  NAME is the name of
537      the symbol.  ABFD, SECTION and ADDRESS identify the location of
538      the reloc; if this is the result of a
539      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
540      ABFD will be NULL.  */
541   bfd_boolean (*unattached_reloc)
542     (struct bfd_link_info *, const char *name,
543      bfd *abfd, asection *section, bfd_vma address);
544   /* A function which is called when a symbol in notice_hash is
545      defined or referenced.  NAME is the symbol.  ABFD, SECTION and
546      ADDRESS are the value of the symbol.  If SECTION is
547      bfd_und_section, this is a reference.  */
548   bfd_boolean (*notice)
549     (struct bfd_link_info *, const char *name,
550      bfd *abfd, asection *section, bfd_vma address);
551   /* General link info message.  */
552   void (*einfo)
553     (const char *fmt, ...);
554 };
555 
556 /* The linker builds link_order structures which tell the code how to
557    include input data in the output file.  */
558 
559 /* These are the types of link_order structures.  */
560 
561 enum bfd_link_order_type
562 {
563   bfd_undefined_link_order,	/* Undefined.  */
564   bfd_indirect_link_order,	/* Built from a section.  */
565   bfd_data_link_order,		/* Set to explicit data.  */
566   bfd_section_reloc_link_order,	/* Relocate against a section.  */
567   bfd_symbol_reloc_link_order	/* Relocate against a symbol.  */
568 };
569 
570 /* This is the link_order structure itself.  These form a chain
571    attached to the output section whose contents they are describing.  */
572 
573 struct bfd_link_order
574 {
575   /* Next link_order in chain.  */
576   struct bfd_link_order *next;
577   /* Type of link_order.  */
578   enum bfd_link_order_type type;
579   /* Offset within output section.  */
580   bfd_vma offset;
581   /* Size within output section.  */
582   bfd_size_type size;
583   /* Type specific information.  */
584   union
585     {
586       struct
587 	{
588 	  /* Section to include.  If this is used, then
589 	     section->output_section must be the section the
590 	     link_order is attached to, section->output_offset must
591 	     equal the link_order offset field, and section->size
592 	     must equal the link_order size field.  Maybe these
593 	     restrictions should be relaxed someday.  */
594 	  asection *section;
595 	} indirect;
596       struct
597 	{
598 	  /* Size of contents, or zero when contents size == size
599 	     within output section.
600 	     A non-zero value allows filling of the output section
601 	     with an arbitrary repeated pattern.  */
602 	  unsigned int size;
603 	  /* Data to put into file.  */
604 	  bfd_byte *contents;
605 	} data;
606       struct
607 	{
608 	  /* Description of reloc to generate.  Used for
609 	     bfd_section_reloc_link_order and
610 	     bfd_symbol_reloc_link_order.  */
611 	  struct bfd_link_order_reloc *p;
612 	} reloc;
613     } u;
614 };
615 
616 /* A linker order of type bfd_section_reloc_link_order or
617    bfd_symbol_reloc_link_order means to create a reloc against a
618    section or symbol, respectively.  This is used to implement -Ur to
619    generate relocs for the constructor tables.  The
620    bfd_link_order_reloc structure describes the reloc that BFD should
621    create.  It is similar to a arelent, but I didn't use arelent
622    because the linker does not know anything about most symbols, and
623    any asymbol structure it creates will be partially meaningless.
624    This information could logically be in the bfd_link_order struct,
625    but I didn't want to waste the space since these types of relocs
626    are relatively rare.  */
627 
628 struct bfd_link_order_reloc
629 {
630   /* Reloc type.  */
631   bfd_reloc_code_real_type reloc;
632 
633   union
634     {
635       /* For type bfd_section_reloc_link_order, this is the section
636 	 the reloc should be against.  This must be a section in the
637 	 output BFD, not any of the input BFDs.  */
638       asection *section;
639       /* For type bfd_symbol_reloc_link_order, this is the name of the
640 	 symbol the reloc should be against.  */
641       const char *name;
642     } u;
643 
644   /* Addend to use.  The object file should contain zero.  The BFD
645      backend is responsible for filling in the contents of the object
646      file correctly.  For some object file formats (e.g., COFF) the
647      addend must be stored into in the object file, and for some
648      (e.g., SPARC a.out) it is kept in the reloc.  */
649   bfd_vma addend;
650 };
651 
652 /* Allocate a new link_order for a section.  */
653 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
654 
655 /* These structures are used to describe version information for the
656    ELF linker.  These structures could be manipulated entirely inside
657    BFD, but it would be a pain.  Instead, the regular linker sets up
658    these structures, and then passes them into BFD.  */
659 
660 /* Glob pattern for a version.  */
661 
662 struct bfd_elf_version_expr
663 {
664   /* Next glob pattern for this version.  */
665   struct bfd_elf_version_expr *next;
666   /* Glob pattern.  */
667   const char *pattern;
668   /* NULL for a glob pattern, otherwise a straight symbol.  */
669   const char *symbol;
670   /* Defined by ".symver".  */
671   unsigned int symver : 1;
672   /* Defined by version script.  */
673   unsigned int script : 1;
674   /* Pattern type.  */
675 #define BFD_ELF_VERSION_C_TYPE		1
676 #define BFD_ELF_VERSION_CXX_TYPE	2
677 #define BFD_ELF_VERSION_JAVA_TYPE	4
678   unsigned int mask : 3;
679 };
680 
681 struct bfd_elf_version_expr_head
682 {
683   /* List of all patterns, both wildcards and non-wildcards.  */
684   struct bfd_elf_version_expr *list;
685   /* Hash table for non-wildcards.  */
686   void *htab;
687   /* Remaining patterns.  */
688   struct bfd_elf_version_expr *remaining;
689   /* What kind of pattern types are present in list (bitmask).  */
690   unsigned int mask;
691 };
692 
693 /* Version dependencies.  */
694 
695 struct bfd_elf_version_deps
696 {
697   /* Next dependency for this version.  */
698   struct bfd_elf_version_deps *next;
699   /* The version which this version depends upon.  */
700   struct bfd_elf_version_tree *version_needed;
701 };
702 
703 /* A node in the version tree.  */
704 
705 struct bfd_elf_version_tree
706 {
707   /* Next version.  */
708   struct bfd_elf_version_tree *next;
709   /* Name of this version.  */
710   const char *name;
711   /* Version number.  */
712   unsigned int vernum;
713   /* Regular expressions for global symbols in this version.  */
714   struct bfd_elf_version_expr_head globals;
715   /* Regular expressions for local symbols in this version.  */
716   struct bfd_elf_version_expr_head locals;
717   /* List of versions which this version depends upon.  */
718   struct bfd_elf_version_deps *deps;
719   /* Index of the version name.  This is used within BFD.  */
720   unsigned int name_indx;
721   /* Whether this version tree was used.  This is used within BFD.  */
722   int used;
723   /* Matching hook.  */
724   struct bfd_elf_version_expr *(*match)
725     (struct bfd_elf_version_expr_head *head,
726      struct bfd_elf_version_expr *prev, const char *sym);
727 };
728 
729 #endif
730