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/* bfdlink.h -- header file for BFD link routines

   Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000

   Free Software Foundation, Inc.

   Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.

This file is part of BFD, the Binary File Descriptor library.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#ifndef BFDLINK_H

#define BFDLINK_H

/* Which symbols to strip during a link.  */

enum bfd_link_strip

{

  strip_none,           /* Don't strip any symbols.  */

  strip_debugger,       /* Strip debugging symbols.  */

  strip_some,           /* keep_hash is the list of symbols to keep.  */

  strip_all             /* Strip all symbols.  */

};

/* Which local symbols to discard during a link.  This is irrelevant

   if strip_all is used.  */

enum bfd_link_discard

{

  discard_sec_merge,    /* Discard local temporary symbols in SEC_MERGE

                           sections.  */

  discard_none,         /* Don't discard any locals.  */

  discard_l,            /* Discard local temporary symbols.  */

  discard_all           /* Discard all locals.  */

};

/* These are the possible types of an entry in the BFD link hash

   table.  */

enum bfd_link_hash_type

{

  bfd_link_hash_new,            /* Symbol is new.  */

  bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */

  bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */

  bfd_link_hash_defined,        /* Symbol is defined.  */

  bfd_link_hash_defweak,        /* Symbol is weak and defined.  */

  bfd_link_hash_common,         /* Symbol is common.  */

  bfd_link_hash_indirect,       /* Symbol is an indirect link.  */

  bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */

};

/* The linking routines use a hash table which uses this structure for

   its elements.  */

struct bfd_link_hash_entry

{

  /* Base hash table entry structure.  */

  struct bfd_hash_entry root;

  /* Type of this entry.  */

  enum bfd_link_hash_type type;

  /* Undefined and common symbols are kept in a linked list through

     this field.  This field is not in the union because that would

     force us to remove entries from the list when we changed their

     type, which would force the list to be doubly linked, which would

     waste more memory.  When an undefined or common symbol is

     created, it should be added to this list, the head of which is in

     the link hash table itself.  As symbols are defined, they need

     not be removed from the list; anything which reads the list must

     doublecheck the symbol type.

     Weak symbols are not kept on this list.

     Defined and defweak symbols use this field as a reference marker.

     If the field is not NULL, or this structure is the tail of the

     undefined symbol list, the symbol has been referenced.  If the

     symbol is undefined and becomes defined, this field will

     automatically be non-NULL since the symbol will have been on the

     undefined symbol list.  */

  struct bfd_link_hash_entry *next;

  /* A union of information depending upon the type.  */

  union

    {

      /* Nothing is kept for bfd_hash_new.  */

      /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */

      struct

        {

          bfd *abfd;            /* BFD symbol was found in.  */

        } undef;

      /* bfd_link_hash_defined, bfd_link_hash_defweak.  */

      struct

        {

          bfd_vma value;        /* Symbol value.  */

          asection *section;    /* Symbol section.  */

        } def;

      /* bfd_link_hash_indirect, bfd_link_hash_warning.  */

      struct

        {

          struct bfd_link_hash_entry *link;     /* Real symbol.  */

          const char *warning;  /* Warning (bfd_link_hash_warning only).  */

        } i;

      /* bfd_link_hash_common.  */

      struct

        {

          /* The linker needs to know three things about common

             symbols: the size, the alignment, and the section in

             which the symbol should be placed.  We store the size

             here, and we allocate a small structure to hold the

             section and the alignment.  The alignment is stored as a

             power of two.  We don't store all the information

             directly because we don't want to increase the size of

             the union; this structure is a major space user in the

             linker.  */

          bfd_size_type size;   /* Common symbol size.  */

          struct bfd_link_hash_common_entry

            {

              unsigned int alignment_power;     /* Alignment.  */

              asection *section;                /* Symbol section.  */

            } *p;

        } c;

    } u;

};

/* This is the link hash table.  It is a derived class of

   bfd_hash_table.  */

struct bfd_link_hash_table

{

  /* The hash table itself.  */

  struct bfd_hash_table table;

  /* The back end which created this hash table.  This indicates the

     type of the entries in the hash table, which is sometimes

     important information when linking object files of different

     types together.  */

  const bfd_target *creator;

  /* A linked list of undefined and common symbols, linked through the

     next field in the bfd_link_hash_entry structure.  */

  struct bfd_link_hash_entry *undefs;

  /* Entries are added to the tail of the undefs list.  */

  struct bfd_link_hash_entry *undefs_tail;

};

/* Look up an entry in a link hash table.  If FOLLOW is true, this

   follows bfd_link_hash_indirect and bfd_link_hash_warning links to

   the real symbol.  */

extern struct bfd_link_hash_entry *bfd_link_hash_lookup

  PARAMS ((struct bfd_link_hash_table *, const char *, boolean create,

           boolean copy, boolean follow));

/* Look up an entry in the main linker hash table if the symbol might

   be wrapped.  This should only be used for references to an

   undefined symbol, not for definitions of a symbol.  */

extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup

  PARAMS ((bfd *, struct bfd_link_info *, const char *, boolean, boolean,

           boolean));

/* Traverse a link hash table.  */

extern void bfd_link_hash_traverse

  PARAMS ((struct bfd_link_hash_table *,

           boolean (*) (struct bfd_link_hash_entry *, PTR),

           PTR));

/* Add an entry to the undefs list.  */

extern void bfd_link_add_undef

  PARAMS ((struct bfd_link_hash_table *, struct bfd_link_hash_entry *));

/* This structure holds all the information needed to communicate

   between BFD and the linker when doing a link.  */

struct bfd_link_info

{

  /* Function callbacks.  */

  const struct bfd_link_callbacks *callbacks;

  /* true if BFD should generate a relocateable object file.  */

  boolean relocateable;

  /* true if BFD should generate relocation information in the final executable.  */

  boolean emitrelocations;

  /* true if BFD should generate a "task linked" object file,

     similar to relocatable but also with globals converted to statics. */

  boolean task_link;

  /* true if BFD should generate a shared object.  */

  boolean shared;

  /* true if BFD should pre-bind symbols in a shared object.  */

  boolean symbolic;

  /* true if BFD should export all symbols in the dynamic symbol table

     of an executable, rather than only those used.  */

  boolean export_dynamic;

  /* true if shared objects should be linked directly, not shared.  */

  boolean static_link;

  /* true if the output file should be in a traditional format.  This

     is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag

     on the output file, but may be checked when reading the input

     files.  */

  boolean traditional_format;

  /* true if we want to produced optimized output files.  This might

     need much more time and therefore must be explicitly selected.  */

  boolean optimize;

  /* true if BFD should generate errors for undefined symbols

     even if generating a shared object.  */

  boolean no_undefined;

  /* true if BFD should allow undefined symbols in shared objects even

     when no_undefined is set to disallow undefined symbols.  The net

     result will be that undefined symbols in regular objects will

     still trigger an error, but undefined symbols in shared objects

     will be ignored.  The implementation of no_undefined makes the

     assumption that the runtime linker will choke on undefined

     symbols.  However there is at least one system (BeOS) where

     undefined symbols in shared libraries is normal since the kernel

     patches them at load time to select which function is most

     appropriate for the current architecture.  I.E. dynamically

     select an appropriate memset function.  Apparently it is also

     normal for HPPA shared libraries to have undefined symbols.  */

  boolean allow_shlib_undefined;

  /* Which symbols to strip.  */

  enum bfd_link_strip strip;

  /* Which local symbols to discard.  */

  enum bfd_link_discard discard;

  /* true if symbols should be retained in memory, false if they

     should be freed and reread.  */

  boolean keep_memory;

  /* The list of input BFD's involved in the link.  These are chained

     together via the link_next field.  */

  bfd *input_bfds;

  /* If a symbol should be created for each input BFD, this is section

     where those symbols should be placed.  It must be a section in

     the output BFD.  It may be NULL, in which case no such symbols

     will be created.  This is to support CREATE_OBJECT_SYMBOLS in the

     linker command language.  */

  asection *create_object_symbols_section;

  /* Hash table handled by BFD.  */

  struct bfd_link_hash_table *hash;

  /* Hash table of symbols to keep.  This is NULL unless strip is

     strip_some.  */

  struct bfd_hash_table *keep_hash;

  /* true if every symbol should be reported back via the notice

     callback.  */

  boolean notice_all;

  /* Hash table of symbols to report back via the notice callback.  If

     this is NULL, and notice_all is false, then no symbols are

     reported back.  */

  struct bfd_hash_table *notice_hash;

  /* Hash table of symbols which are being wrapped (the --wrap linker

     option).  If this is NULL, no symbols are being wrapped.  */

  struct bfd_hash_table *wrap_hash;

  /* If a base output file is wanted, then this points to it */

  PTR base_file;

  /* If non-zero, specifies that branches which are problematic for the

  MPC860 C0 (or earlier) should be checked for and modified.  It gives the

  number of bytes that should be checked at the end of each text page. */

  int mpc860c0;

  /* The function to call when the executable or shared object is

     loaded.  */

  const char *init_function;

  /* The function to call when the executable or shared object is

     unloaded.  */

  const char *fini_function;

  /* true if the new ELF dynamic tags are enabled. */

  boolean new_dtags;

  /* May be used to set DT_FLAGS for ELF. */

  bfd_vma flags;

  /* May be used to set DT_FLAGS_1 for ELF. */

  bfd_vma flags_1;

};

/* This structures holds a set of callback functions.  These are

   called by the BFD linker routines.  The first argument to each

   callback function is the bfd_link_info structure being used.  Each

   function returns a boolean value.  If the function returns false,

   then the BFD function which called it will return with a failure

   indication.  */

struct bfd_link_callbacks

{

  /* A function which is called when an object is added from an

     archive.  ABFD is the archive element being added.  NAME is the

     name of the symbol which caused the archive element to be pulled

     in.  */

  boolean (*add_archive_element) PARAMS ((struct bfd_link_info *,

                                          bfd *abfd,

                                          const char *name));

  /* A function which is called when a symbol is found with multiple

     definitions.  NAME is the symbol which is defined multiple times.

     OBFD is the old BFD, OSEC is the old section, OVAL is the old

     value, NBFD is the new BFD, NSEC is the new section, and NVAL is

     the new value.  OBFD may be NULL.  OSEC and NSEC may be

     bfd_com_section or bfd_ind_section.  */

  boolean (*multiple_definition) PARAMS ((struct bfd_link_info *,

                                          const char *name,

                                          bfd *obfd,

                                          asection *osec,

                                          bfd_vma oval,

                                          bfd *nbfd,

                                          asection *nsec,

                                          bfd_vma nval));

  /* A function which is called when a common symbol is defined

     multiple times.  NAME is the symbol appearing multiple times.

     OBFD is the BFD of the existing symbol; it may be NULL if this is

     not known.  OTYPE is the type of the existing symbol, which may

     be bfd_link_hash_defined, bfd_link_hash_defweak,

     bfd_link_hash_common, or bfd_link_hash_indirect.  If OTYPE is

     bfd_link_hash_common, OSIZE is the size of the existing symbol.

     NBFD is the BFD of the new symbol.  NTYPE is the type of the new

     symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or

     bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE

     is the size of the new symbol.  */

  boolean (*multiple_common) PARAMS ((struct bfd_link_info *,

                                      const char *name,

                                      bfd *obfd,

                                      enum bfd_link_hash_type otype,

                                      bfd_vma osize,

                                      bfd *nbfd,

                                      enum bfd_link_hash_type ntype,

                                      bfd_vma nsize));

  /* A function which is called to add a symbol to a set.  ENTRY is

     the link hash table entry for the set itself (e.g.,

     __CTOR_LIST__).  RELOC is the relocation to use for an entry in

     the set when generating a relocateable file, and is also used to

     get the size of the entry when generating an executable file.

     ABFD, SEC and VALUE identify the value to add to the set.  */

  boolean (*add_to_set) PARAMS ((struct bfd_link_info *,

                                 struct bfd_link_hash_entry *entry,

                                 bfd_reloc_code_real_type reloc,

                                 bfd *abfd, asection *sec, bfd_vma value));

  /* A function which is called when the name of a g++ constructor or

     destructor is found.  This is only called by some object file

     formats.  CONSTRUCTOR is true for a constructor, false for a

     destructor.  This will use BFD_RELOC_CTOR when generating a

     relocateable file.  NAME is the name of the symbol found.  ABFD,

     SECTION and VALUE are the value of the symbol.  */

  boolean (*constructor) PARAMS ((struct bfd_link_info *,

                                  boolean constructor,

                                  const char *name, bfd *abfd, asection *sec,

                                  bfd_vma value));

  /* A function which is called to issue a linker warning.  For

     example, this is called when there is a reference to a warning

     symbol.  WARNING is the warning to be issued.  SYMBOL is the name

     of the symbol which triggered the warning; it may be NULL if

     there is none.  ABFD, SECTION and ADDRESS identify the location

     which trigerred the warning; either ABFD or SECTION or both may

     be NULL if the location is not known.  */

  boolean (*warning) PARAMS ((struct bfd_link_info *,

                              const char *warning, const char *symbol,

                              bfd *abfd, asection *section,

                              bfd_vma address));

  /* A function which is called when a relocation is attempted against

     an undefined symbol.  NAME is the symbol which is undefined.

     ABFD, SECTION and ADDRESS identify the location from which the

     reference is made. FATAL indicates whether an undefined symbol is

     a fatal error or not. In some cases SECTION may be NULL.  */

  boolean (*undefined_symbol) PARAMS ((struct bfd_link_info *,

                                       const char *name, bfd *abfd,

                                       asection *section,

                                       bfd_vma address,

                                       boolean fatal));

  /* A function which is called when a reloc overflow occurs.  NAME is

     the name of the symbol or section the reloc is against,

     RELOC_NAME is the name of the relocation, and ADDEND is any

     addend that is used.  ABFD, SECTION and ADDRESS identify the

     location at which the overflow occurs; if this is the result of a

     bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then

     ABFD will be NULL.  */

  boolean (*reloc_overflow) PARAMS ((struct bfd_link_info *,

                                     const char *name,

                                     const char *reloc_name, bfd_vma addend,

                                     bfd *abfd, asection *section,

                                     bfd_vma address));

  /* A function which is called when a dangerous reloc is performed.

     The canonical example is an a29k IHCONST reloc which does not

     follow an IHIHALF reloc.  MESSAGE is an appropriate message.

     ABFD, SECTION and ADDRESS identify the location at which the

     problem occurred; if this is the result of a

     bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then

     ABFD will be NULL.  */

  boolean (*reloc_dangerous) PARAMS ((struct bfd_link_info *,

                                      const char *message,

                                      bfd *abfd, asection *section,

                                      bfd_vma address));

  /* A function which is called when a reloc is found to be attached

     to a symbol which is not being written out.  NAME is the name of

     the symbol.  ABFD, SECTION and ADDRESS identify the location of

     the reloc; if this is the result of a

     bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then

     ABFD will be NULL.  */

  boolean (*unattached_reloc) PARAMS ((struct bfd_link_info *,

                                       const char *name,

                                       bfd *abfd, asection *section,

                                       bfd_vma address));

  /* A function which is called when a symbol in notice_hash is

     defined or referenced.  NAME is the symbol.  ABFD, SECTION and

     ADDRESS are the value of the symbol.  If SECTION is

     bfd_und_section, this is a reference.  */

  boolean (*notice) PARAMS ((struct bfd_link_info *, const char *name,

                             bfd *abfd, asection *section, bfd_vma address));

};

/* The linker builds link_order structures which tell the code how to

   include input data in the output file.  */

/* These are the types of link_order structures.  */

enum bfd_link_order_type

{

  bfd_undefined_link_order,     /* Undefined.  */

  bfd_indirect_link_order,      /* Built from a section.  */

  bfd_fill_link_order,          /* Fill with a 16 bit constant.  */

  bfd_data_link_order,          /* Set to explicit data.  */

  bfd_section_reloc_link_order, /* Relocate against a section.  */

  bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */

};

/* This is the link_order structure itself.  These form a chain

   attached to the section whose contents they are describing.  */

struct bfd_link_order

{

  /* Next link_order in chain.  */

  struct bfd_link_order *next;

  /* Type of link_order.  */

  enum bfd_link_order_type type;

  /* Offset within output section.  */

  bfd_vma offset;

  /* Size within output section.  */

  bfd_size_type size;

  /* Type specific information.  */

  union

    {

      struct

        {

          /* Section to include.  If this is used, then

             section->output_section must be the section the

             link_order is attached to, section->output_offset must

             equal the link_order offset field, and section->_raw_size

             must equal the link_order size field.  Maybe these

             restrictions should be relaxed someday.  */

          asection *section;

        } indirect;

      struct

        {

          /* Value to fill with.  */

          unsigned int value;

        } fill;

      struct

        {

          /* Data to put into file.  The size field gives the number

             of bytes which this field points to.  */

          bfd_byte *contents;

        } data;

      struct

        {

          /* Description of reloc to generate.  Used for

             bfd_section_reloc_link_order and

             bfd_symbol_reloc_link_order.  */

          struct bfd_link_order_reloc *p;

        } reloc;

    } u;

};

/* A linker order of type bfd_section_reloc_link_order or

   bfd_symbol_reloc_link_order means to create a reloc against a

   section or symbol, respectively.  This is used to implement -Ur to

   generate relocs for the constructor tables.  The

   bfd_link_order_reloc structure describes the reloc that BFD should

   create.  It is similar to a arelent, but I didn't use arelent

   because the linker does not know anything about most symbols, and

   any asymbol structure it creates will be partially meaningless.

   This information could logically be in the bfd_link_order struct,

   but I didn't want to waste the space since these types of relocs

   are relatively rare.  */

struct bfd_link_order_reloc

{

  /* Reloc type.  */

  bfd_reloc_code_real_type reloc;

  union

    {

      /* For type bfd_section_reloc_link_order, this is the section

         the reloc should be against.  This must be a section in the

         output BFD, not any of the input BFDs.  */

      asection *section;

      /* For type bfd_symbol_reloc_link_order, this is the name of the

         symbol the reloc should be against.  */

      const char *name;

    } u;

  /* Addend to use.  The object file should contain zero.  The BFD

     backend is responsible for filling in the contents of the object

     file correctly.  For some object file formats (e.g., COFF) the

     addend must be stored into in the object file, and for some

     (e.g., SPARC a.out) it is kept in the reloc.  */

  bfd_vma addend;

};

/* Allocate a new link_order for a section.  */

extern struct bfd_link_order *bfd_new_link_order PARAMS ((bfd *, asection *));

/* These structures are used to describe version information for the

   ELF linker.  These structures could be manipulated entirely inside

   BFD, but it would be a pain.  Instead, the regular linker sets up

   these structures, and then passes them into BFD.  */

/* Regular expressions for a version.  */

struct bfd_elf_version_expr

{

  /* Next regular expression for this version.  */

  struct bfd_elf_version_expr *next;

  /* Regular expression.  */

  const char *pattern;

  /* Matching function.  */

  int (*match) PARAMS((struct bfd_elf_version_expr *, const char *));

};

/* Version dependencies.  */

struct bfd_elf_version_deps

{

  /* Next dependency for this version.  */

  struct bfd_elf_version_deps *next;

  /* The version which this version depends upon.  */

  struct bfd_elf_version_tree *version_needed;

};

/* A node in the version tree.  */

struct bfd_elf_version_tree

{

  /* Next version.  */

  struct bfd_elf_version_tree *next;

  /* Name of this version.  */

  const char *name;

  /* Version number.  */

  unsigned int vernum;

  /* Regular expressions for global symbols in this version.  */

  struct bfd_elf_version_expr *globals;

  /* Regular expressions for local symbols in this version.  */

  struct bfd_elf_version_expr *locals;

  /* List of versions which this version depends upon.  */

  struct bfd_elf_version_deps *deps;

  /* Index of the version name.  This is used within BFD.  */

  unsigned int name_indx;

  /* Whether this version tree was used.  This is used within BFD.  */

  int used;

};

#endif