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[binutils.git] / bfd / linker.c

/* linker.c -- BFD linker routines
   Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
   2003, 2004, 2005, 2006 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */

#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
#include "bfdlink.h"
#include "genlink.h"

/*
SECTION
        Linker Functions

@cindex Linker
        The linker uses three special entry points in the BFD target
        vector.  It is not necessary to write special routines for
        these entry points when creating a new BFD back end, since
        generic versions are provided.  However, writing them can
        speed up linking and make it use significantly less runtime
        memory.

        The first routine creates a hash table used by the other
        routines.  The second routine adds the symbols from an object
        file to the hash table.  The third routine takes all the
        object files and links them together to create the output
        file.  These routines are designed so that the linker proper
        does not need to know anything about the symbols in the object
        files that it is linking.  The linker merely arranges the
        sections as directed by the linker script and lets BFD handle
        the details of symbols and relocs.

        The second routine and third routines are passed a pointer to
        a <<struct bfd_link_info>> structure (defined in
        <<bfdlink.h>>) which holds information relevant to the link,
        including the linker hash table (which was created by the
        first routine) and a set of callback functions to the linker
        proper.

        The generic linker routines are in <<linker.c>>, and use the
        header file <<genlink.h>>.  As of this writing, the only back
        ends which have implemented versions of these routines are
        a.out (in <<aoutx.h>>) and ECOFF (in <<ecoff.c>>).  The a.out
        routines are used as examples throughout this section.

@menu
@* Creating a Linker Hash Table::
@* Adding Symbols to the Hash Table::
@* Performing the Final Link::
@end menu

INODE
Creating a Linker Hash Table, Adding Symbols to the Hash Table, Linker Functions, Linker Functions
SUBSECTION
        Creating a linker hash table

@cindex _bfd_link_hash_table_create in target vector
@cindex target vector (_bfd_link_hash_table_create)
        The linker routines must create a hash table, which must be
        derived from <<struct bfd_link_hash_table>> described in
        <<bfdlink.c>>.  @xref{Hash Tables}, for information on how to
        create a derived hash table.  This entry point is called using
        the target vector of the linker output file.

        The <<_bfd_link_hash_table_create>> entry point must allocate
        and initialize an instance of the desired hash table.  If the
        back end does not require any additional information to be
        stored with the entries in the hash table, the entry point may
        simply create a <<struct bfd_link_hash_table>>.  Most likely,
        however, some additional information will be needed.

        For example, with each entry in the hash table the a.out
        linker keeps the index the symbol has in the final output file
        (this index number is used so that when doing a relocatable
        link the symbol index used in the output file can be quickly
        filled in when copying over a reloc).  The a.out linker code
        defines the required structures and functions for a hash table
        derived from <<struct bfd_link_hash_table>>.  The a.out linker
        hash table is created by the function
        <<NAME(aout,link_hash_table_create)>>; it simply allocates
        space for the hash table, initializes it, and returns a
        pointer to it.

        When writing the linker routines for a new back end, you will
        generally not know exactly which fields will be required until
        you have finished.  You should simply create a new hash table
        which defines no additional fields, and then simply add fields
        as they become necessary.

INODE
Adding Symbols to the Hash Table, Performing the Final Link, Creating a Linker Hash Table, Linker Functions
SUBSECTION
        Adding symbols to the hash table

@cindex _bfd_link_add_symbols in target vector
@cindex target vector (_bfd_link_add_symbols)
        The linker proper will call the <<_bfd_link_add_symbols>>
        entry point for each object file or archive which is to be
        linked (typically these are the files named on the command
        line, but some may also come from the linker script).  The
        entry point is responsible for examining the file.  For an
        object file, BFD must add any relevant symbol information to
        the hash table.  For an archive, BFD must determine which
        elements of the archive should be used and adding them to the
        link.

        The a.out version of this entry point is
        <<NAME(aout,link_add_symbols)>>.

@menu
@* Differing file formats::
@* Adding symbols from an object file::
@* Adding symbols from an archive::
@end menu

INODE
Differing file formats, Adding symbols from an object file, Adding Symbols to the Hash Table, Adding Symbols to the Hash Table
SUBSUBSECTION
        Differing file formats

        Normally all the files involved in a link will be of the same
        format, but it is also possible to link together different
        format object files, and the back end must support that.  The
        <<_bfd_link_add_symbols>> entry point is called via the target
        vector of the file to be added.  This has an important
        consequence: the function may not assume that the hash table
        is the type created by the corresponding
        <<_bfd_link_hash_table_create>> vector.  All the
        <<_bfd_link_add_symbols>> function can assume about the hash
        table is that it is derived from <<struct
        bfd_link_hash_table>>.

        Sometimes the <<_bfd_link_add_symbols>> function must store
        some information in the hash table entry to be used by the
        <<_bfd_final_link>> function.  In such a case the <<creator>>
        field of the hash table must be checked to make sure that the
        hash table was created by an object file of the same format.

        The <<_bfd_final_link>> routine must be prepared to handle a
        hash entry without any extra information added by the
        <<_bfd_link_add_symbols>> function.  A hash entry without
        extra information will also occur when the linker script
        directs the linker to create a symbol.  Note that, regardless
        of how a hash table entry is added, all the fields will be
        initialized to some sort of null value by the hash table entry
        initialization function.

        See <<ecoff_link_add_externals>> for an example of how to
        check the <<creator>> field before saving information (in this
        case, the ECOFF external symbol debugging information) in a
        hash table entry.

INODE
Adding symbols from an object file, Adding symbols from an archive, Differing file formats, Adding Symbols to the Hash Table
SUBSUBSECTION
        Adding symbols from an object file

        When the <<_bfd_link_add_symbols>> routine is passed an object
        file, it must add all externally visible symbols in that
        object file to the hash table.  The actual work of adding the
        symbol to the hash table is normally handled by the function
        <<_bfd_generic_link_add_one_symbol>>.  The
        <<_bfd_link_add_symbols>> routine is responsible for reading
        all the symbols from the object file and passing the correct
        information to <<_bfd_generic_link_add_one_symbol>>.

        The <<_bfd_link_add_symbols>> routine should not use
        <<bfd_canonicalize_symtab>> to read the symbols.  The point of
        providing this routine is to avoid the overhead of converting
        the symbols into generic <<asymbol>> structures.

@findex _bfd_generic_link_add_one_symbol
        <<_bfd_generic_link_add_one_symbol>> handles the details of
        combining common symbols, warning about multiple definitions,
        and so forth.  It takes arguments which describe the symbol to
        add, notably symbol flags, a section, and an offset.  The
        symbol flags include such things as <<BSF_WEAK>> or
        <<BSF_INDIRECT>>.  The section is a section in the object
        file, or something like <<bfd_und_section_ptr>> for an undefined
        symbol or <<bfd_com_section_ptr>> for a common symbol.

        If the <<_bfd_final_link>> routine is also going to need to
        read the symbol information, the <<_bfd_link_add_symbols>>
        routine should save it somewhere attached to the object file
        BFD.  However, the information should only be saved if the
        <<keep_memory>> field of the <<info>> argument is TRUE, so
        that the <<-no-keep-memory>> linker switch is effective.

        The a.out function which adds symbols from an object file is
        <<aout_link_add_object_symbols>>, and most of the interesting
        work is in <<aout_link_add_symbols>>.  The latter saves
        pointers to the hash tables entries created by
        <<_bfd_generic_link_add_one_symbol>> indexed by symbol number,
        so that the <<_bfd_final_link>> routine does not have to call
        the hash table lookup routine to locate the entry.

INODE
Adding symbols from an archive, , Adding symbols from an object file, Adding Symbols to the Hash Table
SUBSUBSECTION
        Adding symbols from an archive

        When the <<_bfd_link_add_symbols>> routine is passed an
        archive, it must look through the symbols defined by the
        archive and decide which elements of the archive should be
        included in the link.  For each such element it must call the
        <<add_archive_element>> linker callback, and it must add the
        symbols from the object file to the linker hash table.

@findex _bfd_generic_link_add_archive_symbols
        In most cases the work of looking through the symbols in the
        archive should be done by the
        <<_bfd_generic_link_add_archive_symbols>> function.  This
        function builds a hash table from the archive symbol table and
        looks through the list of undefined symbols to see which
        elements should be included.
        <<_bfd_generic_link_add_archive_symbols>> is passed a function
        to call to make the final decision about adding an archive
        element to the link and to do the actual work of adding the
        symbols to the linker hash table.

        The function passed to
        <<_bfd_generic_link_add_archive_symbols>> must read the
        symbols of the archive element and decide whether the archive
        element should be included in the link.  If the element is to
        be included, the <<add_archive_element>> linker callback
        routine must be called with the element as an argument, and
        the elements symbols must be added to the linker hash table
        just as though the element had itself been passed to the
        <<_bfd_link_add_symbols>> function.

        When the a.out <<_bfd_link_add_symbols>> function receives an
        archive, it calls <<_bfd_generic_link_add_archive_symbols>>
        passing <<aout_link_check_archive_element>> as the function
        argument. <<aout_link_check_archive_element>> calls
        <<aout_link_check_ar_symbols>>.  If the latter decides to add
        the element (an element is only added if it provides a real,
        non-common, definition for a previously undefined or common
        symbol) it calls the <<add_archive_element>> callback and then
        <<aout_link_check_archive_element>> calls
        <<aout_link_add_symbols>> to actually add the symbols to the
        linker hash table.

        The ECOFF back end is unusual in that it does not normally
        call <<_bfd_generic_link_add_archive_symbols>>, because ECOFF
        archives already contain a hash table of symbols.  The ECOFF
        back end searches the archive itself to avoid the overhead of
        creating a new hash table.

INODE
Performing the Final Link, , Adding Symbols to the Hash Table, Linker Functions
SUBSECTION
        Performing the final link

@cindex _bfd_link_final_link in target vector
@cindex target vector (_bfd_final_link)
        When all the input files have been processed, the linker calls
        the <<_bfd_final_link>> entry point of the output BFD.  This
        routine is responsible for producing the final output file,
        which has several aspects.  It must relocate the contents of
        the input sections and copy the data into the output sections.
        It must build an output symbol table including any local
        symbols from the input files and the global symbols from the
        hash table.  When producing relocatable output, it must
        modify the input relocs and write them into the output file.
        There may also be object format dependent work to be done.

        The linker will also call the <<write_object_contents>> entry
        point when the BFD is closed.  The two entry points must work
        together in order to produce the correct output file.

        The details of how this works are inevitably dependent upon
        the specific object file format.  The a.out
        <<_bfd_final_link>> routine is <<NAME(aout,final_link)>>.

@menu
@* Information provided by the linker::
@* Relocating the section contents::
@* Writing the symbol table::
@end menu

INODE
Information provided by the linker, Relocating the section contents, Performing the Final Link, Performing the Final Link
SUBSUBSECTION
        Information provided by the linker

        Before the linker calls the <<_bfd_final_link>> entry point,
        it sets up some data structures for the function to use.

        The <<input_bfds>> field of the <<bfd_link_info>> structure
        will point to a list of all the input files included in the
        link.  These files are linked through the <<link_next>> field
        of the <<bfd>> structure.

        Each section in the output file will have a list of
        <<link_order>> structures attached to the <<map_head.link_order>>
        field (the <<link_order>> structure is defined in
        <<bfdlink.h>>).  These structures describe how to create the
        contents of the output section in terms of the contents of
        various input sections, fill constants, and, eventually, other
        types of information.  They also describe relocs that must be
        created by the BFD backend, but do not correspond to any input
        file; this is used to support -Ur, which builds constructors
        while generating a relocatable object file.

INODE
Relocating the section contents, Writing the symbol table, Information provided by the linker, Performing the Final Link
SUBSUBSECTION
        Relocating the section contents

        The <<_bfd_final_link>> function should look through the
        <<link_order>> structures attached to each section of the
        output file.  Each <<link_order>> structure should either be
        handled specially, or it should be passed to the function
        <<_bfd_default_link_order>> which will do the right thing
        (<<_bfd_default_link_order>> is defined in <<linker.c>>).

        For efficiency, a <<link_order>> of type
        <<bfd_indirect_link_order>> whose associated section belongs
        to a BFD of the same format as the output BFD must be handled
        specially.  This type of <<link_order>> describes part of an
        output section in terms of a section belonging to one of the
        input files.  The <<_bfd_final_link>> function should read the
        contents of the section and any associated relocs, apply the
        relocs to the section contents, and write out the modified
        section contents.  If performing a relocatable link, the
        relocs themselves must also be modified and written out.

@findex _bfd_relocate_contents
@findex _bfd_final_link_relocate
        The functions <<_bfd_relocate_contents>> and
        <<_bfd_final_link_relocate>> provide some general support for
        performing the actual relocations, notably overflow checking.
        Their arguments include information about the symbol the
        relocation is against and a <<reloc_howto_type>> argument
        which describes the relocation to perform.  These functions
        are defined in <<reloc.c>>.

        The a.out function which handles reading, relocating, and
        writing section contents is <<aout_link_input_section>>.  The
        actual relocation is done in <<aout_link_input_section_std>>
        and <<aout_link_input_section_ext>>.

INODE
Writing the symbol table, , Relocating the section contents, Performing the Final Link
SUBSUBSECTION
        Writing the symbol table

        The <<_bfd_final_link>> function must gather all the symbols
        in the input files and write them out.  It must also write out
        all the symbols in the global hash table.  This must be
        controlled by the <<strip>> and <<discard>> fields of the
        <<bfd_link_info>> structure.

        The local symbols of the input files will not have been
        entered into the linker hash table.  The <<_bfd_final_link>>
        routine must consider each input file and include the symbols
        in the output file.  It may be convenient to do this when
        looking through the <<link_order>> structures, or it may be
        done by stepping through the <<input_bfds>> list.

        The <<_bfd_final_link>> routine must also traverse the global
        hash table to gather all the externally visible symbols.  It
        is possible that most of the externally visible symbols may be
        written out when considering the symbols of each input file,
        but it is still necessary to traverse the hash table since the
        linker script may have defined some symbols that are not in
        any of the input files.

        The <<strip>> field of the <<bfd_link_info>> structure
        controls which symbols are written out.  The possible values
        are listed in <<bfdlink.h>>.  If the value is <<strip_some>>,
        then the <<keep_hash>> field of the <<bfd_link_info>>
        structure is a hash table of symbols to keep; each symbol
        should be looked up in this hash table, and only symbols which
        are present should be included in the output file.

        If the <<strip>> field of the <<bfd_link_info>> structure
        permits local symbols to be written out, the <<discard>> field
        is used to further controls which local symbols are included
        in the output file.  If the value is <<discard_l>>, then all
        local symbols which begin with a certain prefix are discarded;
        this is controlled by the <<bfd_is_local_label_name>> entry point.

        The a.out backend handles symbols by calling
        <<aout_link_write_symbols>> on each input BFD and then
        traversing the global hash table with the function
        <<aout_link_write_other_symbol>>.  It builds a string table
        while writing out the symbols, which is written to the output
        file at the end of <<NAME(aout,final_link)>>.
*/

static bfd_boolean generic_link_add_object_symbols
  (bfd *, struct bfd_link_info *, bfd_boolean collect);
static bfd_boolean generic_link_add_symbols
  (bfd *, struct bfd_link_info *, bfd_boolean);
static bfd_boolean generic_link_check_archive_element_no_collect
  (bfd *, struct bfd_link_info *, bfd_boolean *);
static bfd_boolean generic_link_check_archive_element_collect
  (bfd *, struct bfd_link_info *, bfd_boolean *);
static bfd_boolean generic_link_check_archive_element
  (bfd *, struct bfd_link_info *, bfd_boolean *, bfd_boolean);
static bfd_boolean generic_link_add_symbol_list
  (bfd *, struct bfd_link_info *, bfd_size_type count, asymbol **,
   bfd_boolean);
static bfd_boolean generic_add_output_symbol
  (bfd *, size_t *psymalloc, asymbol *);
static bfd_boolean default_data_link_order
  (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *);
static bfd_boolean default_indirect_link_order
  (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *,
   bfd_boolean);

/* The link hash table structure is defined in bfdlink.h.  It provides
   a base hash table which the backend specific hash tables are built
   upon.  */

/* Routine to create an entry in the link hash table.  */

struct bfd_hash_entry *
_bfd_link_hash_newfunc (struct bfd_hash_entry *entry,
                        struct bfd_hash_table *table,
                        const char *string)
{
  /* Allocate the structure if it has not already been allocated by a
     subclass.  */
  if (entry == NULL)
    {
      entry = bfd_hash_allocate (table, sizeof (struct bfd_link_hash_entry));
      if (entry == NULL)
        return entry;
    }

  /* Call the allocation method of the superclass.  */
  entry = bfd_hash_newfunc (entry, table, string);
  if (entry)
    {
      struct bfd_link_hash_entry *h = (struct bfd_link_hash_entry *) entry;

      /* Initialize the local fields.  */
      h->type = bfd_link_hash_new;
      memset (&h->u.undef.next, 0,
              (sizeof (struct bfd_link_hash_entry)
               - offsetof (struct bfd_link_hash_entry, u.undef.next)));
    }

  return entry;
}

/* Initialize a link hash table.  The BFD argument is the one
   responsible for creating this table.  */

bfd_boolean
_bfd_link_hash_table_init
  (struct bfd_link_hash_table *table,
   bfd *abfd,
   struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *,
                                      struct bfd_hash_table *,
                                      const char *),
   unsigned int entsize)
{
  table->creator = abfd->xvec;
  table->undefs = NULL;
  table->undefs_tail = NULL;
  table->type = bfd_link_generic_hash_table;

  return bfd_hash_table_init (&table->table, newfunc, entsize);
}

/* Look up a symbol in a link hash table.  If follow is TRUE, we
   follow bfd_link_hash_indirect and bfd_link_hash_warning links to
   the real symbol.  */

struct bfd_link_hash_entry *
bfd_link_hash_lookup (struct bfd_link_hash_table *table,
                      const char *string,
                      bfd_boolean create,
                      bfd_boolean copy,
                      bfd_boolean follow)
{
  struct bfd_link_hash_entry *ret;

  ret = ((struct bfd_link_hash_entry *)
         bfd_hash_lookup (&table->table, string, create, copy));

  if (follow && ret != NULL)
    {
      while (ret->type == bfd_link_hash_indirect
             || ret->type == bfd_link_hash_warning)
        ret = ret->u.i.link;
    }

  return ret;
}

/* Look up a symbol 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.  */

struct bfd_link_hash_entry *
bfd_wrapped_link_hash_lookup (bfd *abfd,
                              struct bfd_link_info *info,
                              const char *string,
                              bfd_boolean create,
                              bfd_boolean copy,
                              bfd_boolean follow)
{
  bfd_size_type amt;

  if (info->wrap_hash != NULL)
    {
      const char *l;
      char prefix = '\0';

      l = string;
      if (*l == bfd_get_symbol_leading_char (abfd) || *l == info->wrap_char)
        {
          prefix = *l;
          ++l;
        }

#undef WRAP
#define WRAP "__wrap_"

      if (bfd_hash_lookup (info->wrap_hash, l, FALSE, FALSE) != NULL)
        {
          char *n;
          struct bfd_link_hash_entry *h;

          /* This symbol is being wrapped.  We want to replace all
             references to SYM with references to __wrap_SYM.  */

          amt = strlen (l) + sizeof WRAP + 1;
          n = bfd_malloc (amt);
          if (n == NULL)
            return NULL;

          n[0] = prefix;
          n[1] = '\0';
          strcat (n, WRAP);
          strcat (n, l);
          h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow);
          free (n);
          return h;
        }

#undef WRAP

#undef REAL
#define REAL "__real_"

      if (*l == '_'
          && strncmp (l, REAL, sizeof REAL - 1) == 0
          && bfd_hash_lookup (info->wrap_hash, l + sizeof REAL - 1,
                              FALSE, FALSE) != NULL)
        {
          char *n;
          struct bfd_link_hash_entry *h;

          /* This is a reference to __real_SYM, where SYM is being
             wrapped.  We want to replace all references to __real_SYM
             with references to SYM.  */

          amt = strlen (l + sizeof REAL - 1) + 2;
          n = bfd_malloc (amt);
          if (n == NULL)
            return NULL;

          n[0] = prefix;
          n[1] = '\0';
          strcat (n, l + sizeof REAL - 1);
          h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow);
          free (n);
          return h;
        }

#undef REAL
    }

  return bfd_link_hash_lookup (info->hash, string, create, copy, follow);
}

/* Traverse a generic link hash table.  The only reason this is not a
   macro is to do better type checking.  This code presumes that an
   argument passed as a struct bfd_hash_entry * may be caught as a
   struct bfd_link_hash_entry * with no explicit cast required on the
   call.  */

void
bfd_link_hash_traverse
  (struct bfd_link_hash_table *table,
   bfd_boolean (*func) (struct bfd_link_hash_entry *, void *),
   void *info)
{
  bfd_hash_traverse (&table->table,
                     (bfd_boolean (*) (struct bfd_hash_entry *, void *)) func,
                     info);
}

/* Add a symbol to the linker hash table undefs list.  */

void
bfd_link_add_undef (struct bfd_link_hash_table *table,
                    struct bfd_link_hash_entry *h)
{
  BFD_ASSERT (h->u.undef.next == NULL);
  if (table->undefs_tail != NULL)
    table->undefs_tail->u.undef.next = h;
  if (table->undefs == NULL)
    table->undefs = h;
  table->undefs_tail = h;
}

/* The undefs list was designed so that in normal use we don't need to
   remove entries.  However, if symbols on the list are changed from
   bfd_link_hash_undefined to either bfd_link_hash_undefweak or
   bfd_link_hash_new for some reason, then they must be removed from the
   list.  Failure to do so might result in the linker attempting to add
   the symbol to the list again at a later stage.  */

void
bfd_link_repair_undef_list (struct bfd_link_hash_table *table)
{
  struct bfd_link_hash_entry **pun;

  pun = &table->undefs;
  while (*pun != NULL)
    {
      struct bfd_link_hash_entry *h = *pun;

      if (h->type == bfd_link_hash_new
          || h->type == bfd_link_hash_undefweak)
        {
          *pun = h->u.undef.next;
          h->u.undef.next = NULL;
          if (h == table->undefs_tail)
            {
              if (pun == &table->undefs)
                table->undefs_tail = NULL;
              else
                /* pun points at an u.undef.next field.  Go back to
                   the start of the link_hash_entry.  */
                table->undefs_tail = (struct bfd_link_hash_entry *)
                  ((char *) pun - ((char *) &h->u.undef.next - (char *) h));
              break;
            }
        }
      else
        pun = &h->u.undef.next;
    }
}
\f
/* Routine to create an entry in a generic link hash table.  */

struct bfd_hash_entry *
_bfd_generic_link_hash_newfunc (struct bfd_hash_entry *entry,
                                struct bfd_hash_table *table,
                                const char *string)
{
  /* Allocate the structure if it has not already been allocated by a
     subclass.  */
  if (entry == NULL)
    {
      entry =
        bfd_hash_allocate (table, sizeof (struct generic_link_hash_entry));
      if (entry == NULL)
        return entry;
    }

  /* Call the allocation method of the superclass.  */
  entry = _bfd_link_hash_newfunc (entry, table, string);
  if (entry)
    {
      struct generic_link_hash_entry *ret;

      /* Set local fields.  */
      ret = (struct generic_link_hash_entry *) entry;
      ret->written = FALSE;
      ret->sym = NULL;
    }

  return entry;
}

/* Create a generic link hash table.  */

struct bfd_link_hash_table *
_bfd_generic_link_hash_table_create (bfd *abfd)
{
  struct generic_link_hash_table *ret;
  bfd_size_type amt = sizeof (struct generic_link_hash_table);

  ret = bfd_malloc (amt);
  if (ret == NULL)
    return NULL;
  if (! _bfd_link_hash_table_init (&ret->root, abfd,
                                   _bfd_generic_link_hash_newfunc,
                                   sizeof (struct generic_link_hash_entry)))
    {
      free (ret);
      return NULL;
    }
  return &ret->root;
}

void
_bfd_generic_link_hash_table_free (struct bfd_link_hash_table *hash)
{
  struct generic_link_hash_table *ret
    = (struct generic_link_hash_table *) hash;

  bfd_hash_table_free (&ret->root.table);
  free (ret);
}

/* Grab the symbols for an object file when doing a generic link.  We
   store the symbols in the outsymbols field.  We need to keep them
   around for the entire link to ensure that we only read them once.
   If we read them multiple times, we might wind up with relocs and
   the hash table pointing to different instances of the symbol
   structure.  */

static bfd_boolean
generic_link_read_symbols (bfd *abfd)
{
  if (bfd_get_outsymbols (abfd) == NULL)
    {
      long symsize;
      long symcount;

      symsize = bfd_get_symtab_upper_bound (abfd);
      if (symsize < 0)
        return FALSE;
      bfd_get_outsymbols (abfd) = bfd_alloc (abfd, symsize);
      if (bfd_get_outsymbols (abfd) == NULL && symsize != 0)
        return FALSE;
      symcount = bfd_canonicalize_symtab (abfd, bfd_get_outsymbols (abfd));
      if (symcount < 0)
        return FALSE;
      bfd_get_symcount (abfd) = symcount;
    }

  return TRUE;
}
\f
/* Generic function to add symbols to from an object file to the
   global hash table.  This version does not automatically collect
   constructors by name.  */

bfd_boolean
_bfd_generic_link_add_symbols (bfd *abfd, struct bfd_link_info *info)
{
  return generic_link_add_symbols (abfd, info, FALSE);
}

/* Generic function to add symbols from an object file to the global
   hash table.  This version automatically collects constructors by
   name, as the collect2 program does.  It should be used for any
   target which does not provide some other mechanism for setting up
   constructors and destructors; these are approximately those targets
   for which gcc uses collect2 and do not support stabs.  */

bfd_boolean
_bfd_generic_link_add_symbols_collect (bfd *abfd, struct bfd_link_info *info)
{
  return generic_link_add_symbols (abfd, info, TRUE);
}

/* Indicate that we are only retrieving symbol values from this
   section.  We want the symbols to act as though the values in the
   file are absolute.  */

void
_bfd_generic_link_just_syms (asection *sec,
                             struct bfd_link_info *info ATTRIBUTE_UNUSED)
{
  sec->output_section = bfd_abs_section_ptr;
  sec->output_offset = sec->vma;
}

/* Add symbols from an object file to the global hash table.  */

static bfd_boolean
generic_link_add_symbols (bfd *abfd,
                          struct bfd_link_info *info,
                          bfd_boolean collect)
{
  bfd_boolean ret;

  switch (bfd_get_format (abfd))
    {
    case bfd_object:
      ret = generic_link_add_object_symbols (abfd, info, collect);
      break;
    case bfd_archive:
      ret = (_bfd_generic_link_add_archive_symbols
             (abfd, info,
              (collect
               ? generic_link_check_archive_element_collect
               : generic_link_check_archive_element_no_collect)));
      break;
    default:
      bfd_set_error (bfd_error_wrong_format);
      ret = FALSE;
    }

  return ret;
}

/* Add symbols from an object file to the global hash table.  */

static bfd_boolean
generic_link_add_object_symbols (bfd *abfd,
                                 struct bfd_link_info *info,
                                 bfd_boolean collect)
{
  bfd_size_type symcount;
  struct bfd_symbol **outsyms;

  if (! generic_link_read_symbols (abfd))
    return FALSE;
  symcount = _bfd_generic_link_get_symcount (abfd);
  outsyms = _bfd_generic_link_get_symbols (abfd);
  return generic_link_add_symbol_list (abfd, info, symcount, outsyms, collect);
}
\f
/* We build a hash table of all symbols defined in an archive.  */

/* An archive symbol may be defined by multiple archive elements.
   This linked list is used to hold the elements.  */

struct archive_list
{
  struct archive_list *next;
  unsigned int indx;
};

/* An entry in an archive hash table.  */

struct archive_hash_entry
{
  struct bfd_hash_entry root;
  /* Where the symbol is defined.  */
  struct archive_list *defs;
};

/* An archive hash table itself.  */

struct archive_hash_table
{
  struct bfd_hash_table table;
};

/* Create a new entry for an archive hash table.  */

static struct bfd_hash_entry *
archive_hash_newfunc (struct bfd_hash_entry *entry,
                      struct bfd_hash_table *table,
                      const char *string)
{
  struct archive_hash_entry *ret = (struct archive_hash_entry *) entry;

  /* Allocate the structure if it has not already been allocated by a
     subclass.  */
  if (ret == NULL)
    ret = bfd_hash_allocate (table, sizeof (struct archive_hash_entry));
  if (ret == NULL)
    return NULL;

  /* Call the allocation method of the superclass.  */
  ret = ((struct archive_hash_entry *)
         bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));

  if (ret)
    {
      /* Initialize the local fields.  */
      ret->defs = NULL;
    }

  return &ret->root;
}

/* Initialize an archive hash table.  */

static bfd_boolean
archive_hash_table_init
  (struct archive_hash_table *table,
   struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *,
                                      struct bfd_hash_table *,
                                      const char *),
   unsigned int entsize)
{
  return bfd_hash_table_init (&table->table, newfunc, entsize);
}

/* Look up an entry in an archive hash table.  */

#define archive_hash_lookup(t, string, create, copy) \
  ((struct archive_hash_entry *) \
   bfd_hash_lookup (&(t)->table, (string), (create), (copy)))

/* Allocate space in an archive hash table.  */

#define archive_hash_allocate(t, size) bfd_hash_allocate (&(t)->table, (size))

/* Free an archive hash table.  */

#define archive_hash_table_free(t) bfd_hash_table_free (&(t)->table)

/* Generic function to add symbols from an archive file to the global
   hash file.  This function presumes that the archive symbol table
   has already been read in (this is normally done by the
   bfd_check_format entry point).  It looks through the undefined and
   common symbols and searches the archive symbol table for them.  If
   it finds an entry, it includes the associated object file in the
   link.

   The old linker looked through the archive symbol table for
   undefined symbols.  We do it the other way around, looking through
   undefined symbols for symbols defined in the archive.  The
   advantage of the newer scheme is that we only have to look through
   the list of undefined symbols once, whereas the old method had to
   re-search the symbol table each time a new object file was added.

   The CHECKFN argument is used to see if an object file should be
   included.  CHECKFN should set *PNEEDED to TRUE if the object file
   should be included, and must also call the bfd_link_info
   add_archive_element callback function and handle adding the symbols
   to the global hash table.  CHECKFN should only return FALSE if some
   sort of error occurs.

   For some formats, such as a.out, it is possible to look through an
   object file but not actually include it in the link.  The
   archive_pass field in a BFD is used to avoid checking the symbols
   of an object files too many times.  When an object is included in
   the link, archive_pass is set to -1.  If an object is scanned but
   not included, archive_pass is set to the pass number.  The pass
   number is incremented each time a new object file is included.  The
   pass number is used because when a new object file is included it
   may create new undefined symbols which cause a previously examined
   object file to be included.  */

bfd_boolean
_bfd_generic_link_add_archive_symbols
  (bfd *abfd,
   struct bfd_link_info *info,
   bfd_boolean (*checkfn) (bfd *, struct bfd_link_info *, bfd_boolean *))
{
  carsym *arsyms;
  carsym *arsym_end;
  register carsym *arsym;
  int pass;
  struct archive_hash_table arsym_hash;
  unsigned int indx;
  struct bfd_link_hash_entry **pundef;

  if (! bfd_has_map (abfd))
    {
      /* An empty archive is a special case.  */
      if (bfd_openr_next_archived_file (abfd, NULL) == NULL)
        return TRUE;
      bfd_set_error (bfd_error_no_armap);
      return FALSE;
    }

  arsyms = bfd_ardata (abfd)->symdefs;
  arsym_end = arsyms + bfd_ardata (abfd)->symdef_count;

  /* In order to quickly determine whether an symbol is defined in
     this archive, we build a hash table of the symbols.  */
  if (! archive_hash_table_init (&arsym_hash, archive_hash_newfunc,
                                 sizeof (struct archive_hash_entry)))
    return FALSE;
  for (arsym = arsyms, indx = 0; arsym < arsym_end; arsym++, indx++)
    {
      struct archive_hash_entry *arh;
      struct archive_list *l, **pp;

      arh = archive_hash_lookup (&arsym_hash, arsym->name, TRUE, FALSE);
      if (arh == NULL)
        goto error_return;
      l = ((struct archive_list *)
           archive_hash_allocate (&arsym_hash, sizeof (struct archive_list)));
      if (l == NULL)
        goto error_return;
      l->indx = indx;
      for (pp = &arh->defs; *pp != NULL; pp = &(*pp)->next)
        ;
      *pp = l;
      l->next = NULL;
    }

  /* The archive_pass field in the archive itself is used to
     initialize PASS, sine we may search the same archive multiple
     times.  */
  pass = abfd->archive_pass + 1;

  /* New undefined symbols are added to the end of the list, so we
     only need to look through it once.  */
  pundef = &info->hash->undefs;
  while (*pundef != NULL)
    {
      struct bfd_link_hash_entry *h;
      struct archive_hash_entry *arh;
      struct archive_list *l;

      h = *pundef;

      /* When a symbol is defined, it is not necessarily removed from
         the list.  */
      if (h->type != bfd_link_hash_undefined
          && h->type != bfd_link_hash_common)
        {
          /* Remove this entry from the list, for general cleanliness
             and because we are going to look through the list again
             if we search any more libraries.  We can't remove the
             entry if it is the tail, because that would lose any
             entries we add to the list later on (it would also cause
             us to lose track of whether the symbol has been
             referenced).  */
          if (*pundef != info->hash->undefs_tail)
            *pundef = (*pundef)->u.undef.next;
          else
            pundef = &(*pundef)->u.undef.next;
          continue;
        }

      /* Look for this symbol in the archive symbol map.  */
      arh = archive_hash_lookup (&arsym_hash, h->root.string, FALSE, FALSE);
      if (arh == NULL)
        {
          /* If we haven't found the exact symbol we're looking for,
             let's look for its import thunk */
          if (info->pei386_auto_import)
            {
              bfd_size_type amt = strlen (h->root.string) + 10;
              char *buf = bfd_malloc (amt);
              if (buf == NULL)
                return FALSE;

              sprintf (buf, "__imp_%s", h->root.string);
              arh = archive_hash_lookup (&arsym_hash, buf, FALSE, FALSE);
              free(buf);
            }
          if (arh == NULL)
            {
              pundef = &(*pundef)->u.undef.next;
              continue;
            }
        }
      /* Look at all the objects which define this symbol.  */
      for (l = arh->defs; l != NULL; l = l->next)
        {
          bfd *element;
          bfd_boolean needed;

          /* If the symbol has gotten defined along the way, quit.  */
          if (h->type != bfd_link_hash_undefined
              && h->type != bfd_link_hash_common)
            break;

          element = bfd_get_elt_at_index (abfd, l->indx);
          if (element == NULL)
            goto error_return;

          /* If we've already included this element, or if we've
             already checked it on this pass, continue.  */
          if (element->archive_pass == -1
              || element->archive_pass == pass)
            continue;

          /* If we can't figure this element out, just ignore it.  */
          if (! bfd_check_format (element, bfd_object))
            {
              element->archive_pass = -1;
              continue;
            }

          /* CHECKFN will see if this element should be included, and
             go ahead and include it if appropriate.  */
          if (! (*checkfn) (element, info, &needed))
            goto error_return;

          if (! needed)
            element->archive_pass = pass;
          else
            {
              element->archive_pass = -1;

              /* Increment the pass count to show that we may need to
                 recheck object files which were already checked.  */
              ++pass;
            }
        }

      pundef = &(*pundef)->u.undef.next;
    }

  archive_hash_table_free (&arsym_hash);

  /* Save PASS in case we are called again.  */
  abfd->archive_pass = pass;

  return TRUE;

 error_return:
  archive_hash_table_free (&arsym_hash);
  return FALSE;
}
\f
/* See if we should include an archive element.  This version is used
   when we do not want to automatically collect constructors based on
   the symbol name, presumably because we have some other mechanism
   for finding them.  */

static bfd_boolean
generic_link_check_archive_element_no_collect (
                                               bfd *abfd,
                                               struct bfd_link_info *info,
                                               bfd_boolean *pneeded)
{
  return generic_link_check_archive_element (abfd, info, pneeded, FALSE);
}

/* See if we should include an archive element.  This version is used
   when we want to automatically collect constructors based on the
   symbol name, as collect2 does.  */

static bfd_boolean
generic_link_check_archive_element_collect (bfd *abfd,
                                            struct bfd_link_info *info,
                                            bfd_boolean *pneeded)
{
  return generic_link_check_archive_element (abfd, info, pneeded, TRUE);
}

/* See if we should include an archive element.  Optionally collect
   constructors.  */

static bfd_boolean
generic_link_check_archive_element (bfd *abfd,
                                    struct bfd_link_info *info,
                                    bfd_boolean *pneeded,
                                    bfd_boolean collect)
{
  asymbol **pp, **ppend;

  *pneeded = FALSE;

  if (! generic_link_read_symbols (abfd))
    return FALSE;

  pp = _bfd_generic_link_get_symbols (abfd);
  ppend = pp + _bfd_generic_link_get_symcount (abfd);
  for (; pp < ppend; pp++)
    {
      asymbol *p;
      struct bfd_link_hash_entry *h;

      p = *pp;

      /* We are only interested in globally visible symbols.  */
      if (! bfd_is_com_section (p->section)
          && (p->flags & (BSF_GLOBAL | BSF_INDIRECT | BSF_WEAK)) == 0)
        continue;

      /* We are only interested if we know something about this
         symbol, and it is undefined or common.  An undefined weak
         symbol (type bfd_link_hash_undefweak) is not considered to be
         a reference when pulling files out of an archive.  See the
         SVR4 ABI, p. 4-27.  */
      h = bfd_link_hash_lookup (info->hash, bfd_asymbol_name (p), FALSE,
                                FALSE, TRUE);
      if (h == NULL
          || (h->type != bfd_link_hash_undefined
              && h->type != bfd_link_hash_common))
        continue;

      /* P is a symbol we are looking for.  */

      if (! bfd_is_com_section (p->section))
        {
          bfd_size_type symcount;
          asymbol **symbols;

          /* This object file defines this symbol, so pull it in.  */
          if (! (*info->callbacks->add_archive_element) (info, abfd,
                                                         bfd_asymbol_name (p)))
            return FALSE;
          symcount = _bfd_generic_link_get_symcount (abfd);
          symbols = _bfd_generic_link_get_symbols (abfd);
          if (! generic_link_add_symbol_list (abfd, info, symcount,
                                              symbols, collect))
            return FALSE;
          *pneeded = TRUE;
          return TRUE;
        }

      /* P is a common symbol.  */

      if (h->type == bfd_link_hash_undefined)
        {
          bfd *symbfd;
          bfd_vma size;
          unsigned int power;

          symbfd = h->u.undef.abfd;
          if (symbfd == NULL)
            {
              /* This symbol was created as undefined from outside
                 BFD.  We assume that we should link in the object
                 file.  This is for the -u option in the linker.  */
              if (! (*info->callbacks->add_archive_element)
                  (info, abfd, bfd_asymbol_name (p)))
                return FALSE;
              *pneeded = TRUE;
              return TRUE;
            }

          /* Turn the symbol into a common symbol but do not link in
             the object file.  This is how a.out works.  Object
             formats that require different semantics must implement
             this function differently.  This symbol is already on the
             undefs list.  We add the section to a common section
             attached to symbfd to ensure that it is in a BFD which
             will be linked in.  */
          h->type = bfd_link_hash_common;
          h->u.c.p =
            bfd_hash_allocate (&info->hash->table,
                               sizeof (struct bfd_link_hash_common_entry));
          if (h->u.c.p == NULL)
            return FALSE;

          size = bfd_asymbol_value (p);
          h->u.c.size = size;

          power = bfd_log2 (size);
          if (power > 4)
            power = 4;
          h->u.c.p->alignment_power = power;

          if (p->section == bfd_com_section_ptr)
            h->u.c.p->section = bfd_make_section_old_way (symbfd, "COMMON");
          else
            h->u.c.p->section = bfd_make_section_old_way (symbfd,
                                                          p->section->name);
          h->u.c.p->section->flags = SEC_ALLOC;
        }
      else
        {
          /* Adjust the size of the common symbol if necessary.  This
             is how a.out works.  Object formats that require
             different semantics must implement this function
             differently.  */
          if (bfd_asymbol_value (p) > h->u.c.size)
            h->u.c.size = bfd_asymbol_value (p);
        }
    }

  /* This archive element is not needed.  */
  return TRUE;
}

/* Add the symbols from an object file to the global hash table.  ABFD
   is the object file.  INFO is the linker information.  SYMBOL_COUNT
   is the number of symbols.  SYMBOLS is the list of symbols.  COLLECT
   is TRUE if constructors should be automatically collected by name
   as is done by collect2.  */

static bfd_boolean
generic_link_add_symbol_list (bfd *abfd,
                              struct bfd_link_info *info,
                              bfd_size_type symbol_count,
                              asymbol **symbols,
                              bfd_boolean collect)
{
  asymbol **pp, **ppend;

  pp = symbols;
  ppend = symbols + symbol_count;
  for (; pp < ppend; pp++)
    {
      asymbol *p;

      p = *pp;

      if ((p->flags & (BSF_INDIRECT
                       | BSF_WARNING
                       | BSF_GLOBAL
                       | BSF_CONSTRUCTOR
                       | BSF_WEAK)) != 0
          || bfd_is_und_section (bfd_get_section (p))
          || bfd_is_com_section (bfd_get_section (p))
          || bfd_is_ind_section (bfd_get_section (p)))
        {
          const char *name;
          const char *string;
          struct generic_link_hash_entry *h;
          struct bfd_link_hash_entry *bh;

          name = bfd_asymbol_name (p);
          if (((p->flags & BSF_INDIRECT) != 0
               || bfd_is_ind_section (p->section))
              && pp + 1 < ppend)
            {
              pp++;
              string = bfd_asymbol_name (*pp);
            }
          else if ((p->flags & BSF_WARNING) != 0
                   && pp + 1 < ppend)
            {
              /* The name of P is actually the warning string, and the
                 next symbol is the one to warn about.  */
              string = name;
              pp++;
              name = bfd_asymbol_name (*pp);
            }
          else
            string = NULL;

          bh = NULL;
          if (! (_bfd_generic_link_add_one_symbol
                 (info, abfd, name, p->flags, bfd_get_section (p),
                  p->value, string, FALSE, collect, &bh)))
            return FALSE;
          h = (struct generic_link_hash_entry *) bh;

          /* If this is a constructor symbol, and the linker didn't do
             anything with it, then we want to just pass the symbol
             through to the output file.  This will happen when
             linking with -r.  */
          if ((p->flags & BSF_CONSTRUCTOR) != 0
              && (h == NULL || h->root.type == bfd_link_hash_new))
            {
              p->udata.p = NULL;
              continue;
            }

          /* Save the BFD symbol so that we don't lose any backend
             specific information that may be attached to it.  We only
             want this one if it gives more information than the
             existing one; we don't want to replace a defined symbol
             with an undefined one.  This routine may be called with a
             hash table other than the generic hash table, so we only
             do this if we are certain that the hash table is a
             generic one.  */
          if (info->hash->creator == abfd->xvec)
            {
              if (h->sym == NULL
                  || (! bfd_is_und_section (bfd_get_section (p))
                      && (! bfd_is_com_section (bfd_get_section (p))
                          || bfd_is_und_section (bfd_get_section (h->sym)))))
                {
                  h->sym = p;
                  /* BSF_OLD_COMMON is a hack to support COFF reloc
                     reading, and it should go away when the COFF
                     linker is switched to the new version.  */
                  if (bfd_is_com_section (bfd_get_section (p)))
                    p->flags |= BSF_OLD_COMMON;
                }
            }

          /* Store a back pointer from the symbol to the hash
             table entry for the benefit of relaxation code until
             it gets rewritten to not use asymbol structures.
             Setting this is also used to check whether these
             symbols were set up by the generic linker.  */
          p->udata.p = h;
        }
    }

  return TRUE;
}
\f
/* We use a state table to deal with adding symbols from an object
   file.  The first index into the state table describes the symbol
   from the object file.  The second index into the state table is the
   type of the symbol in the hash table.  */

/* The symbol from the object file is turned into one of these row
   values.  */

enum link_row
{
  UNDEF_ROW,            /* Undefined.  */
  UNDEFW_ROW,           /* Weak undefined.  */
  DEF_ROW,              /* Defined.  */
  DEFW_ROW,             /* Weak defined.  */
  COMMON_ROW,           /* Common.  */
  INDR_ROW,             /* Indirect.  */
  WARN_ROW,             /* Warning.  */
  SET_ROW               /* Member of set.  */
};

/* apparently needed for Hitachi 3050R(HI-UX/WE2)? */
#undef FAIL

/* The actions to take in the state table.  */

enum link_action
{
  FAIL,         /* Abort.  */
  UND,          /* Mark symbol undefined.  */
  WEAK,         /* Mark symbol weak undefined.  */
  DEF,          /* Mark symbol defined.  */
  DEFW,         /* Mark symbol weak defined.  */
  COM,          /* Mark symbol common.  */
  REF,          /* Mark defined symbol referenced.  */
  CREF,         /* Possibly warn about common reference to defined symbol.  */
  CDEF,         /* Define existing common symbol.  */
  NOACT,        /* No action.  */
  BIG,          /* Mark symbol common using largest size.  */
  MDEF,         /* Multiple definition error.  */
  MIND,         /* Multiple indirect symbols.  */
  IND,          /* Make indirect symbol.  */
  CIND,         /* Make indirect symbol from existing common symbol.  */
  SET,          /* Add value to set.  */
  MWARN,        /* Make warning symbol.  */
  WARN,         /* Issue warning.  */
  CWARN,        /* Warn if referenced, else MWARN.  */
  CYCLE,        /* Repeat with symbol pointed to.  */
  REFC,         /* Mark indirect symbol referenced and then CYCLE.  */
  WARNC         /* Issue warning and then CYCLE.  */
};

/* The state table itself.  The first index is a link_row and the
   second index is a bfd_link_hash_type.  */

static const enum link_action link_action[8][8] =
{
  /* current\prev    new    undef  undefw def    defw   com    indr   warn  */
  /* UNDEF_ROW  */  {UND,   NOACT, UND,   REF,   REF,   NOACT, REFC,  WARNC },
  /* UNDEFW_ROW */  {WEAK,  NOACT, NOACT, REF,   REF,   NOACT, REFC,  WARNC },
  /* DEF_ROW    */  {DEF,   DEF,   DEF,   MDEF,  DEF,   CDEF,  MDEF,  CYCLE },
  /* DEFW_ROW   */  {DEFW,  DEFW,  DEFW,  NOACT, NOACT, NOACT, NOACT, CYCLE },
  /* COMMON_ROW */  {COM,   COM,   COM,   CREF,  COM,   BIG,   REFC,  WARNC },
  /* INDR_ROW   */  {IND,   IND,   IND,   MDEF,  IND,   CIND,  MIND,  CYCLE },
  /* WARN_ROW   */  {MWARN, WARN,  WARN,  CWARN, CWARN, WARN,  CWARN, NOACT },
  /* SET_ROW    */  {SET,   SET,   SET,   SET,   SET,   SET,   CYCLE, CYCLE }
};

/* Most of the entries in the LINK_ACTION table are straightforward,
   but a few are somewhat subtle.

   A reference to an indirect symbol (UNDEF_ROW/indr or
   UNDEFW_ROW/indr) is counted as a reference both to the indirect
   symbol and to the symbol the indirect symbol points to.

   A reference to a warning symbol (UNDEF_ROW/warn or UNDEFW_ROW/warn)
   causes the warning to be issued.

   A common definition of an indirect symbol (COMMON_ROW/indr) is
   treated as a multiple definition error.  Likewise for an indirect
   definition of a common symbol (INDR_ROW/com).

   An indirect definition of a warning (INDR_ROW/warn) does not cause
   the warning to be issued.

   If a warning is created for an indirect symbol (WARN_ROW/indr) no
   warning is created for the symbol the indirect symbol points to.

   Adding an entry to a set does not count as a reference to a set,
   and no warning is issued (SET_ROW/warn).  */

/* Return the BFD in which a hash entry has been defined, if known.  */

static bfd *
hash_entry_bfd (struct bfd_link_hash_entry *h)
{
  while (h->type == bfd_link_hash_warning)
    h = h->u.i.link;
  switch (h->type)
    {
    default:
      return NULL;
    case bfd_link_hash_undefined:
    case bfd_link_hash_undefweak:
      return h->u.undef.abfd;
    case bfd_link_hash_defined:
    case bfd_link_hash_defweak:
      return h->u.def.section->owner;
    case bfd_link_hash_common:
      return h->u.c.p->section->owner;
    }
  /*NOTREACHED*/
}

/* Add a symbol to the global hash table.
   ABFD is the BFD the symbol comes from.
   NAME is the name of the symbol.
   FLAGS is the BSF_* bits associated with the symbol.
   SECTION is the section in which the symbol is defined; this may be
     bfd_und_section_ptr or bfd_com_section_ptr.
   VALUE is the value of the symbol, relative to the section.
   STRING is used for either an indirect symbol, in which case it is
     the name of the symbol to indirect to, or a warning symbol, in
     which case it is the warning string.
   COPY is TRUE if NAME or STRING must be copied into locally
     allocated memory if they need to be saved.
   COLLECT is TRUE if we should automatically collect gcc constructor
     or destructor names as collect2 does.
   HASHP, if not NULL, is a place to store the created hash table
     entry; if *HASHP is not NULL, the caller has already looked up
     the hash table entry, and stored it in *HASHP.  */

bfd_boolean
_bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
                                  bfd *abfd,
                                  const char *name,
                                  flagword flags,
                                  asection *section,
                                  bfd_vma value,
                                  const char *string,
                                  bfd_boolean copy,
                                  bfd_boolean collect,
                                  struct bfd_link_hash_entry **hashp)
{
  enum link_row row;
  struct bfd_link_hash_entry *h;
  bfd_boolean cycle;

  if (bfd_is_ind_section (section)
      || (flags & BSF_INDIRECT) != 0)
    row = INDR_ROW;
  else if ((flags & BSF_WARNING) != 0)
    row = WARN_ROW;
  else if ((flags & BSF_CONSTRUCTOR) != 0)
    row = SET_ROW;
  else if (bfd_is_und_section (section))
    {
      if ((flags & BSF_WEAK) != 0)
        row = UNDEFW_ROW;
      else
        row = UNDEF_ROW;
    }
  else if ((flags & BSF_WEAK) != 0)
    row = DEFW_ROW;
  else if (bfd_is_com_section (section))
    row = COMMON_ROW;
  else
    row = DEF_ROW;

  if (hashp != NULL && *hashp != NULL)
    h = *hashp;
  else
    {
      if (row == UNDEF_ROW || row == UNDEFW_ROW)
        h = bfd_wrapped_link_hash_lookup (abfd, info, name, TRUE, copy, FALSE);
      else
        h = bfd_link_hash_lookup (info->hash, name, TRUE, copy, FALSE);
      if (h == NULL)
        {
          if (hashp != NULL)
            *hashp = NULL;
          return FALSE;
        }
    }

  if (info->notice_all
      || (info->notice_hash != NULL
          && bfd_hash_lookup (info->notice_hash, name, FALSE, FALSE) != NULL))
    {
      if (! (*info->callbacks->notice) (info, h->root.string, abfd, section,
                                        value))
        return FALSE;
    }

  if (hashp != NULL)
    *hashp = h;

  do
    {
      enum link_action action;

      cycle = FALSE;
      action = link_action[(int) row][(int) h->type];
      switch (action)
        {
        case FAIL:
          abort ();

        case NOACT:
          /* Do nothing.  */
          break;

        case UND:
          /* Make a new undefined symbol.  */
          h->type = bfd_link_hash_undefined;
          h->u.undef.abfd = abfd;
          bfd_link_add_undef (info->hash, h);
          break;

        case WEAK:
          /* Make a new weak undefined symbol.  */
          h->type = bfd_link_hash_undefweak;
          h->u.undef.abfd = abfd;
          h->u.undef.weak = abfd;
          break;

        case CDEF:
          /* We have found a definition for a symbol which was
             previously common.  */
          BFD_ASSERT (h->type == bfd_link_hash_common);
          if (! ((*info->callbacks->multiple_common)
                 (info, h->root.string,
                  h->u.c.p->section->owner, bfd_link_hash_common, h->u.c.size,
                  abfd, bfd_link_hash_defined, 0)))
            return FALSE;
          /* Fall through.  */
        case DEF:
        case DEFW:
          {
            enum bfd_link_hash_type oldtype;

            /* Define a symbol.  */
            oldtype = h->type;
            if (action == DEFW)
              h->type = bfd_link_hash_defweak;
            else
              h->type = bfd_link_hash_defined;
            h->u.def.section = section;
            h->u.def.value = value;

            /* If we have been asked to, we act like collect2 and
               identify all functions that might be global
               constructors and destructors and pass them up in a
               callback.  We only do this for certain object file
               types, since many object file types can handle this
               automatically.  */
            if (collect && name[0] == '_')
              {
                const char *s;

                /* A constructor or destructor name starts like this:
                   _+GLOBAL_[_.$][ID][_.$] where the first [_.$] and
                   the second are the same character (we accept any
                   character there, in case a new object file format
                   comes along with even worse naming restrictions).  */

#define CONS_PREFIX "GLOBAL_"
#define CONS_PREFIX_LEN (sizeof CONS_PREFIX - 1)

                s = name + 1;
                while (*s == '_')
                  ++s;
                if (s[0] == 'G'
                    && strncmp (s, CONS_PREFIX, CONS_PREFIX_LEN - 1) == 0)
                  {
                    char c;

                    c = s[CONS_PREFIX_LEN + 1];
                    if ((c == 'I' || c == 'D')
                        && s[CONS_PREFIX_LEN] == s[CONS_PREFIX_LEN + 2])
                      {
                        /* If this is a definition of a symbol which
                           was previously weakly defined, we are in
                           trouble.  We have already added a
                           constructor entry for the weak defined
                           symbol, and now we are trying to add one
                           for the new symbol.  Fortunately, this case
                           should never arise in practice.  */
                        if (oldtype == bfd_link_hash_defweak)
                          abort ();

                        if (! ((*info->callbacks->constructor)
                               (info, c == 'I',
                                h->root.string, abfd, section, value)))
                          return FALSE;
                      }
                  }
              }
          }

          break;

        case COM:
          /* We have found a common definition for a symbol.  */
          if (h->type == bfd_link_hash_new)
            bfd_link_add_undef (info->hash, h);
          h->type = bfd_link_hash_common;
          h->u.c.p =
            bfd_hash_allocate (&info->hash->table,
                               sizeof (struct bfd_link_hash_common_entry));
          if (h->u.c.p == NULL)
            return FALSE;

          h->u.c.size = value;

          /* Select a default alignment based on the size.  This may
             be overridden by the caller.  */
          {
            unsigned int power;

            power = bfd_log2 (value);
            if (power > 4)
              power = 4;
            h->u.c.p->alignment_power = power;
          }

          /* The section of a common symbol is only used if the common
             symbol is actually allocated.  It basically provides a
             hook for the linker script to decide which output section
             the common symbols should be put in.  In most cases, the
             section of a common symbol will be bfd_com_section_ptr,
             the code here will choose a common symbol section named
             "COMMON", and the linker script will contain *(COMMON) in
             the appropriate place.  A few targets use separate common
             sections for small symbols, and they require special
             handling.  */
          if (section == bfd_com_section_ptr)
            {
              h->u.c.p->section = bfd_make_section_old_way (abfd, "COMMON");
              h->u.c.p->section->flags = SEC_ALLOC;
            }
          else if (section->owner != abfd)
            {
              h->u.c.p->section = bfd_make_section_old_way (abfd,
                                                            section->name);
              h->u.c.p->section->flags = SEC_ALLOC;
            }
          else
            h->u.c.p->section = section;
          break;

        case REF:
          /* A reference to a defined symbol.  */
          if (h->u.undef.next == NULL && info->hash->undefs_tail != h)
            h->u.undef.next = h;
          break;

        case BIG:
          /* We have found a common definition for a symbol which
             already had a common definition.  Use the maximum of the
             two sizes, and use the section required by the larger symbol.  */
          BFD_ASSERT (h->type == bfd_link_hash_common);
          if (! ((*info->callbacks->multiple_common)
                 (info, h->root.string,
                  h->u.c.p->section->owner, bfd_link_hash_common, h->u.c.size,
                  abfd, bfd_link_hash_common, value)))
            return FALSE;
          if (value > h->u.c.size)
            {
              unsigned int power;

              h->u.c.size = value;

              /* Select a default alignment based on the size.  This may
                 be overridden by the caller.  */
              power = bfd_log2 (value);
              if (power > 4)
                power = 4;
              h->u.c.p->alignment_power = power;

              /* Some systems have special treatment for small commons,
                 hence we want to select the section used by the larger
                 symbol.  This makes sure the symbol does not go in a
                 small common section if it is now too large.  */
              if (section == bfd_com_section_ptr)
                {
                  h->u.c.p->section
                    = bfd_make_section_old_way (abfd, "COMMON");
                  h->u.c.p->section->flags = SEC_ALLOC;
                }
              else if (section->owner != abfd)
                {
                  h->u.c.p->section
                    = bfd_make_section_old_way (abfd, section->name);
                  h->u.c.p->section->flags = SEC_ALLOC;
                }
              else
                h->u.c.p->section = section;
            }
          break;

        case CREF:
          {
            bfd *obfd;

            /* We have found a common definition for a symbol which
               was already defined.  FIXME: It would nice if we could
               report the BFD which defined an indirect symbol, but we
               don't have anywhere to store the information.  */
            if (h->type == bfd_link_hash_defined
                || h->type == bfd_link_hash_defweak)
              obfd = h->u.def.section->owner;
            else
              obfd = NULL;
            if (! ((*info->callbacks->multiple_common)
                   (info, h->root.string, obfd, h->type, 0,
                    abfd, bfd_link_hash_common, value)))
              return FALSE;
          }
          break;

        case MIND:
          /* Multiple indirect symbols.  This is OK if they both point
             to the same symbol.  */
          if (strcmp (h->u.i.link->root.string, string) == 0)
            break;
          /* Fall through.  */
        case MDEF:
          /* Handle a multiple definition.  */
          if (!info->allow_multiple_definition)
            {
              asection *msec = NULL;
              bfd_vma mval = 0;

              switch (h->type)
                {
                case bfd_link_hash_defined:
                  msec = h->u.def.section;
                  mval = h->u.def.value;
                  break;
                case bfd_link_hash_indirect:
                  msec = bfd_ind_section_ptr;
                  mval = 0;
                  break;
                default:
                  abort ();
                }

              /* Ignore a redefinition of an absolute symbol to the
                 same value; it's harmless.  */
              if (h->type == bfd_link_hash_defined
                  && bfd_is_abs_section (msec)
                  && bfd_is_abs_section (section)
                  && value == mval)
                break;

              if (! ((*info->callbacks->multiple_definition)
                     (info, h->root.string, msec->owner, msec, mval,
                      abfd, section, value)))
                return FALSE;
            }
          break;

        case CIND:
          /* Create an indirect symbol from an existing common symbol.  */
          BFD_ASSERT (h->type == bfd_link_hash_common);
          if (! ((*info->callbacks->multiple_common)
                 (info, h->root.string,
                  h->u.c.p->section->owner, bfd_link_hash_common, h->u.c.size,
                  abfd, bfd_link_hash_indirect, 0)))
            return FALSE;
          /* Fall through.  */
        case IND:
          /* Create an indirect symbol.  */
          {
            struct bfd_link_hash_entry *inh;

            /* STRING is the name of the symbol we want to indirect
               to.  */
            inh = bfd_wrapped_link_hash_lookup (abfd, info, string, TRUE,
                                                copy, FALSE);
            if (inh == NULL)
              return FALSE;
            if (inh->type == bfd_link_hash_indirect
                && inh->u.i.link == h)
              {
                (*_bfd_error_handler)
                  (_("%B: indirect symbol `%s' to `%s' is a loop"),
                   abfd, name, string);
                bfd_set_error (bfd_error_invalid_operation);
                return FALSE;
              }
            if (inh->type == bfd_link_hash_new)
              {
                inh->type = bfd_link_hash_undefined;
                inh->u.undef.abfd = abfd;
                bfd_link_add_undef (info->hash, inh);
              }

            /* If the indirect symbol has been referenced, we need to
               push the reference down to the symbol we are
               referencing.  */
            if (h->type != bfd_link_hash_new)
              {
                row = UNDEF_ROW;
                cycle = TRUE;
              }

            h->type = bfd_link_hash_indirect;
            h->u.i.link = inh;
          }
          break;

        case SET:
          /* Add an entry to a set.  */
          if (! (*info->callbacks->add_to_set) (info, h, BFD_RELOC_CTOR,
                                                abfd, section, value))
            return FALSE;
          break;

        case WARNC:
          /* Issue a warning and cycle.  */
          if (h->u.i.warning != NULL)
            {
              if (! (*info->callbacks->warning) (info, h->u.i.warning,
                                                 h->root.string, abfd,
                                                 NULL, 0))
                return FALSE;
              /* Only issue a warning once.  */
              h->u.i.warning = NULL;
            }
          /* Fall through.  */
        case CYCLE:
          /* Try again with the referenced symbol.  */
          h = h->u.i.link;
          cycle = TRUE;
          break;

        case REFC:
          /* A reference to an indirect symbol.  */
          if (h->u.undef.next == NULL && info->hash->undefs_tail != h)
            h->u.undef.next = h;
          h = h->u.i.link;
          cycle = TRUE;
          break;

        case WARN:
          /* Issue a warning.  */
          if (! (*info->callbacks->warning) (info, string, h->root.string,
                                             hash_entry_bfd (h), NULL, 0))
            return FALSE;
          break;

        case CWARN:
          /* Warn if this symbol has been referenced already,
             otherwise add a warning.  A symbol has been referenced if
             the u.undef.next field is not NULL, or it is the tail of the
             undefined symbol list.  The REF case above helps to
             ensure this.  */
          if (h->u.undef.next != NULL || info->hash->undefs_tail == h)
            {
              if (! (*info->callbacks->warning) (info, string, h->root.string,
                                                 hash_entry_bfd (h), NULL, 0))
                return FALSE;
              break;
            }
          /* Fall through.  */
        case MWARN:
          /* Make a warning symbol.  */
          {
            struct bfd_link_hash_entry *sub;

            /* STRING is the warning to give.  */
            sub = ((struct bfd_link_hash_entry *)
                   ((*info->hash->table.newfunc)
                    (NULL, &info->hash->table, h->root.string)));
            if (sub == NULL)
              return FALSE;
            *sub = *h;
            sub->type = bfd_link_hash_warning;
            sub->u.i.link = h;
            if (! copy)
              sub->u.i.warning = string;
            else
              {
                char *w;
                size_t len = strlen (string) + 1;

                w = bfd_hash_allocate (&info->hash->table, len);
                if (w == NULL)
                  return FALSE;
                memcpy (w, string, len);
                sub->u.i.warning = w;
              }

            bfd_hash_replace (&info->hash->table,
                              (struct bfd_hash_entry *) h,
                              (struct bfd_hash_entry *) sub);
            if (hashp != NULL)
              *hashp = sub;
          }
          break;
        }
    }
  while (cycle);

  return TRUE;
}
\f
/* Generic final link routine.  */

bfd_boolean
_bfd_generic_final_link (bfd *abfd, struct bfd_link_info *info)
{
  bfd *sub;
  asection *o;
  struct bfd_link_order *p;
  size_t outsymalloc;
  struct generic_write_global_symbol_info wginfo;

  bfd_get_outsymbols (abfd) = NULL;
  bfd_get_symcount (abfd) = 0;
  outsymalloc = 0;

  /* Mark all sections which will be included in the output file.  */
  for (o = abfd->sections; o != NULL; o = o->next)
    for (p = o->map_head.link_order; p != NULL; p = p->next)
      if (p->type == bfd_indirect_link_order)
        p->u.indirect.section->linker_mark = TRUE;

  /* Build the output symbol table.  */
  for (sub = info->input_bfds; sub != NULL; sub = sub->link_next)
    if (! _bfd_generic_link_output_symbols (abfd, sub, info, &outsymalloc))
      return FALSE;

  /* Accumulate the global symbols.  */
  wginfo.info = info;
  wginfo.output_bfd = abfd;
  wginfo.psymalloc = &outsymalloc;
  _bfd_generic_link_hash_traverse (_bfd_generic_hash_table (info),
                                   _bfd_generic_link_write_global_symbol,
                                   &wginfo);

  /* Make sure we have a trailing NULL pointer on OUTSYMBOLS.  We
     shouldn't really need one, since we have SYMCOUNT, but some old
     code still expects one.  */
  if (! generic_add_output_symbol (abfd, &outsymalloc, NULL))
    return FALSE;

  if (info->relocatable)
    {
      /* Allocate space for the output relocs for each section.  */
      for (o = abfd->sections; o != NULL; o = o->next)
        {
          o->reloc_count = 0;
          for (p = o->map_head.link_order; p != NULL; p = p->next)
            {
              if (p->type == bfd_section_reloc_link_order
                  || p->type == bfd_symbol_reloc_link_order)
                ++o->reloc_count;
              else if (p->type == bfd_indirect_link_order)
                {
                  asection *input_section;
                  bfd *input_bfd;
                  long relsize;
                  arelent **relocs;
                  asymbol **symbols;
                  long reloc_count;

                  input_section = p->u.indirect.section;
                  input_bfd = input_section->owner;
                  relsize = bfd_get_reloc_upper_bound (input_bfd,
                                                       input_section);
                  if (relsize < 0)
                    return FALSE;
                  relocs = bfd_malloc (relsize);
                  if (!relocs && relsize != 0)
                    return FALSE;
                  symbols = _bfd_generic_link_get_symbols (input_bfd);
                  reloc_count = bfd_canonicalize_reloc (input_bfd,
                                                        input_section,
                                                        relocs,
                                                        symbols);
                  free (relocs);
                  if (reloc_count < 0)
                    return FALSE;
                  BFD_ASSERT ((unsigned long) reloc_count
                              == input_section->reloc_count);
                  o->reloc_count += reloc_count;
                }
            }
          if (o->reloc_count > 0)
            {
              bfd_size_type amt;

              amt = o->reloc_count;
              amt *= sizeof (arelent *);
              o->orelocation = bfd_alloc (abfd, amt);
              if (!o->orelocation)
                return FALSE;
              o->flags |= SEC_RELOC;
              /* Reset the count so that it can be used as an index
                 when putting in the output relocs.  */
              o->reloc_count = 0;
            }
        }
    }

  /* Handle all the link order information for the sections.  */
  for (o = abfd->sections; o != NULL; o = o->next)
    {
      for (p = o->map_head.link_order; p != NULL; p = p->next)
        {
          switch (p->type)
            {
            case bfd_section_reloc_link_order:
            case bfd_symbol_reloc_link_order:
              if (! _bfd_generic_reloc_link_order (abfd, info, o, p))
                return FALSE;
              break;
            case bfd_indirect_link_order:
              if (! default_indirect_link_order (abfd, info, o, p, TRUE))
                return FALSE;
              break;
            default:
              if (! _bfd_default_link_order (abfd, info, o, p))
                return FALSE;
              break;
            }
        }
    }

  return TRUE;
}

/* Add an output symbol to the output BFD.  */

static bfd_boolean
generic_add_output_symbol (bfd *output_bfd, size_t *psymalloc, asymbol *sym)
{
  if (bfd_get_symcount (output_bfd) >= *psymalloc)
    {
      asymbol **newsyms;
      bfd_size_type amt;

      if (*psymalloc == 0)
        *psymalloc = 124;
      else
        *psymalloc *= 2;
      amt = *psymalloc;
      amt *= sizeof (asymbol *);
      newsyms = bfd_realloc (bfd_get_outsymbols (output_bfd), amt);
      if (newsyms == NULL)
        return FALSE;
      bfd_get_outsymbols (output_bfd) = newsyms;
    }

  bfd_get_outsymbols (output_bfd) [bfd_get_symcount (output_bfd)] = sym;
  if (sym != NULL)
    ++ bfd_get_symcount (output_bfd);

  return TRUE;
}

/* Handle the symbols for an input BFD.  */

bfd_boolean
_bfd_generic_link_output_symbols (bfd *output_bfd,
                                  bfd *input_bfd,
                                  struct bfd_link_info *info,
                                  size_t *psymalloc)
{
  asymbol **sym_ptr;
  asymbol **sym_end;

  if (! generic_link_read_symbols (input_bfd))
    return FALSE;

  /* Create a filename symbol if we are supposed to.  */
  if (info->create_object_symbols_section != NULL)
    {
      asection *sec;

      for (sec = input_bfd->sections; sec != NULL; sec = sec->next)
        {
          if (sec->output_section == info->create_object_symbols_section)
            {
              asymbol *newsym;

              newsym = bfd_make_empty_symbol (input_bfd);
              if (!newsym)
                return FALSE;
              newsym->name = input_bfd->filename;
              newsym->value = 0;
              newsym->flags = BSF_LOCAL | BSF_FILE;
              newsym->section = sec;

              if (! generic_add_output_symbol (output_bfd, psymalloc,
                                               newsym))
                return FALSE;

              break;
            }
        }
    }

  /* Adjust the values of the globally visible symbols, and write out
     local symbols.  */
  sym_ptr = _bfd_generic_link_get_symbols (input_bfd);
  sym_end = sym_ptr + _bfd_generic_link_get_symcount (input_bfd);
  for (; sym_ptr < sym_end; sym_ptr++)
    {
      asymbol *sym;
      struct generic_link_hash_entry *h;
      bfd_boolean output;

      h = NULL;
      sym = *sym_ptr;
      if ((sym->flags & (BSF_INDIRECT
                         | BSF_WARNING
                         | BSF_GLOBAL
                         | BSF_CONSTRUCTOR
                         | BSF_WEAK)) != 0
          || bfd_is_und_section (bfd_get_section (sym))
          || bfd_is_com_section (bfd_get_section (sym))
          || bfd_is_ind_section (bfd_get_section (sym)))
        {
          if (sym->udata.p != NULL)
            h = sym->udata.p;
          else if ((sym->flags & BSF_CONSTRUCTOR) != 0)
            {
              /* This case normally means that the main linker code
                 deliberately ignored this constructor symbol.  We
                 should just pass it through.  This will screw up if
                 the constructor symbol is from a different,
                 non-generic, object file format, but the case will
                 only arise when linking with -r, which will probably
                 fail anyhow, since there will be no way to represent
                 the relocs in the output format being used.  */
              h = NULL;
            }
          else if (bfd_is_und_section (bfd_get_section (sym)))
            h = ((struct generic_link_hash_entry *)
                 bfd_wrapped_link_hash_lookup (output_bfd, info,
                                               bfd_asymbol_name (sym),
                                               FALSE, FALSE, TRUE));
          else
            h = _bfd_generic_link_hash_lookup (_bfd_generic_hash_table (info),
                                               bfd_asymbol_name (sym),
                                               FALSE, FALSE, TRUE);

          if (h != NULL)
            {
              /* Force all references to this symbol to point to
                 the same area in memory.  It is possible that
                 this routine will be called with a hash table
                 other than a generic hash table, so we double
                 check that.  */
              if (info->hash->creator == input_bfd->xvec)
                {
                  if (h->sym != NULL)
                    *sym_ptr = sym = h->sym;
                }

              switch (h->root.type)
                {
                default:
                case bfd_link_hash_new:
                  abort ();
                case bfd_link_hash_undefined:
                  break;
                case bfd_link_hash_undefweak:
                  sym->flags |= BSF_WEAK;
                  break;
                case bfd_link_hash_indirect:
                  h = (struct generic_link_hash_entry *) h->root.u.i.link;
                  /* fall through */
                case bfd_link_hash_defined:
                  sym->flags |= BSF_GLOBAL;
                  sym->flags &=~ BSF_CONSTRUCTOR;
                  sym->value = h->root.u.def.value;
                  sym->section = h->root.u.def.section;
                  break;
                case bfd_link_hash_defweak:
                  sym->flags |= BSF_WEAK;
                  sym->flags &=~ BSF_CONSTRUCTOR;
                  sym->value = h->root.u.def.value;
                  sym->section = h->root.u.def.section;
                  break;
                case bfd_link_hash_common:
                  sym->value = h->root.u.c.size;
                  sym->flags |= BSF_GLOBAL;
                  if (! bfd_is_com_section (sym->section))
                    {
                      BFD_ASSERT (bfd_is_und_section (sym->section));
                      sym->section = bfd_com_section_ptr;
                    }
                  /* We do not set the section of the symbol to
                     h->root.u.c.p->section.  That value was saved so
                     that we would know where to allocate the symbol
                     if it was defined.  In this case the type is
                     still bfd_link_hash_common, so we did not define
                     it, so we do not want to use that section.  */
                  break;
                }
            }
        }

      /* This switch is straight from the old code in
         write_file_locals in ldsym.c.  */
      if (info->strip == strip_all
          || (info->strip == strip_some
              && bfd_hash_lookup (info->keep_hash, bfd_asymbol_name (sym),
                                  FALSE, FALSE) == NULL))
        output = FALSE;
      else if ((sym->flags & (BSF_GLOBAL | BSF_WEAK)) != 0)
        {
          /* If this symbol is marked as occurring now, rather
             than at the end, output it now.  This is used for
             COFF C_EXT FCN symbols.  FIXME: There must be a
             better way.  */
          if (bfd_asymbol_bfd (sym) == input_bfd
              && (sym->flags & BSF_NOT_AT_END) != 0)
            output = TRUE;
          else
            output = FALSE;
        }
      else if (bfd_is_ind_section (sym->section))
        output = FALSE;
      else if ((sym->flags & BSF_DEBUGGING) != 0)
        {
          if (info->strip == strip_none)
            output = TRUE;
          else
            output = FALSE;
        }
      else if (bfd_is_und_section (sym->section)
               || bfd_is_com_section (sym->section))
        output = FALSE;
      else if ((sym->flags & BSF_LOCAL) != 0)
        {
          if ((sym->flags & BSF_WARNING) != 0)
            output = FALSE;
          else
            {
              switch (info->discard)
                {
                default:
                case discard_all:
                  output = FALSE;
                  break;
                case discard_sec_merge:
                  output = TRUE;
                  if (info->relocatable
                      || ! (sym->section->flags & SEC_MERGE))
                    break;
                  /* FALLTHROUGH */
                case discard_l:
                  if (bfd_is_local_label (input_bfd, sym))
                    output = FALSE;
                  else
                    output = TRUE;
                  break;
                case discard_none:
                  output = TRUE;
                  break;
                }
            }
        }
      else if ((sym->flags & BSF_CONSTRUCTOR))
        {
          if (info->strip != strip_all)
            output = TRUE;
          else
            output = FALSE;
        }
      else
        abort ();

      /* If this symbol is in a section which is not being included
         in the output file, then we don't want to output the
         symbol.  */
      if (!bfd_is_abs_section (sym->section)
          && bfd_section_removed_from_list (output_bfd,
                                            sym->section->output_section))
        output = FALSE;

      if (output)
        {
          if (! generic_add_output_symbol (output_bfd, psymalloc, sym))
            return FALSE;
          if (h != NULL)
            h->written = TRUE;
        }
    }

  return TRUE;
}

/* Set the section and value of a generic BFD symbol based on a linker
   hash table entry.  */

static void
set_symbol_from_hash (asymbol *sym, struct bfd_link_hash_entry *h)
{
  switch (h->type)
    {
    default:
      abort ();
      break;
    case bfd_link_hash_new:
      /* This can happen when a constructor symbol is seen but we are
         not building constructors.  */
      if (sym->section != NULL)
        {
          BFD_ASSERT ((sym->flags & BSF_CONSTRUCTOR) != 0);
        }
      else
        {
          sym->flags |= BSF_CONSTRUCTOR;
          sym->section = bfd_abs_section_ptr;
          sym->value = 0;
        }
      break;
    case bfd_link_hash_undefined:
      sym->section = bfd_und_section_ptr;
      sym->value = 0;
      break;
    case bfd_link_hash_undefweak:
      sym->section = bfd_und_section_ptr;
      sym->value = 0;
      sym->flags |= BSF_WEAK;
      break;
    case bfd_link_hash_defined:
      sym->section = h->u.def.section;
      sym->value = h->u.def.value;
      break;
    case bfd_link_hash_defweak:
      sym->flags |= BSF_WEAK;
      sym->section = h->u.def.section;
      sym->value = h->u.def.value;
      break;
    case bfd_link_hash_common:
      sym->value = h->u.c.size;
      if (sym->section == NULL)
        sym->section = bfd_com_section_ptr;
      else if (! bfd_is_com_section (sym->section))
        {
          BFD_ASSERT (bfd_is_und_section (sym->section));
          sym->section = bfd_com_section_ptr;
        }
      /* Do not set the section; see _bfd_generic_link_output_symbols.  */
      break;
    case bfd_link_hash_indirect:
    case bfd_link_hash_warning:
      /* FIXME: What should we do here?  */
      break;
    }
}

/* Write out a global symbol, if it hasn't already been written out.
   This is called for each symbol in the hash table.  */

bfd_boolean
_bfd_generic_link_write_global_symbol (struct generic_link_hash_entry *h,
                                       void *data)
{
  struct generic_write_global_symbol_info *wginfo = data;
  asymbol *sym;

  if (h->root.type == bfd_link_hash_warning)
    h = (struct generic_link_hash_entry *) h->root.u.i.link;

  if (h->written)
    return TRUE;

  h->written = TRUE;

  if (wginfo->info->strip == strip_all
      || (wginfo->info->strip == strip_some
          && bfd_hash_lookup (wginfo->info->keep_hash, h->root.root.string,
                              FALSE, FALSE) == NULL))
    return TRUE;

  if (h->sym != NULL)
    sym = h->sym;
  else
    {
      sym = bfd_make_empty_symbol (wginfo->output_bfd);
      if (!sym)
        return FALSE;
      sym->name = h->root.root.string;
      sym->flags = 0;
    }

  set_symbol_from_hash (sym, &h->root);

  sym->flags |= BSF_GLOBAL;

  if (! generic_add_output_symbol (wginfo->output_bfd, wginfo->psymalloc,
                                   sym))
    {
      /* FIXME: No way to return failure.  */
      abort ();
    }

  return TRUE;
}

/* Create a relocation.  */

bfd_boolean
_bfd_generic_reloc_link_order (bfd *abfd,
                               struct bfd_link_info *info,
                               asection *sec,
                               struct bfd_link_order *link_order)
{
  arelent *r;

  if (! info->relocatable)
    abort ();
  if (sec->orelocation == NULL)
    abort ();

  r = bfd_alloc (abfd, sizeof (arelent));
  if (r == NULL)
    return FALSE;

  r->address = link_order->offset;
  r->howto = bfd_reloc_type_lookup (abfd, link_order->u.reloc.p->reloc);
  if (r->howto == 0)
    {
      bfd_set_error (bfd_error_bad_value);
      return FALSE;
    }

  /* Get the symbol to use for the relocation.  */
  if (link_order->type == bfd_section_reloc_link_order)
    r->sym_ptr_ptr = link_order->u.reloc.p->u.section->symbol_ptr_ptr;
  else
    {
      struct generic_link_hash_entry *h;

      h = ((struct generic_link_hash_entry *)
           bfd_wrapped_link_hash_lookup (abfd, info,
                                         link_order->u.reloc.p->u.name,
                                         FALSE, FALSE, TRUE));
      if (h == NULL
          || ! h->written)
        {
          if (! ((*info->callbacks->unattached_reloc)
                 (info, link_order->u.reloc.p->u.name, NULL, NULL, 0)))
            return FALSE;
          bfd_set_error (bfd_error_bad_value);
          return FALSE;
        }
      r->sym_ptr_ptr = &h->sym;
    }

  /* If this is an inplace reloc, write the addend to the object file.
     Otherwise, store it in the reloc addend.  */
  if (! r->howto->partial_inplace)
    r->addend = link_order->u.reloc.p->addend;
  else
    {
      bfd_size_type size;
      bfd_reloc_status_type rstat;
      bfd_byte *buf;
      bfd_boolean ok;
      file_ptr loc;

      size = bfd_get_reloc_size (r->howto);
      buf = bfd_zmalloc (size);
      if (buf == NULL)
        return FALSE;
      rstat = _bfd_relocate_contents (r->howto, abfd,
                                      (bfd_vma) link_order->u.reloc.p->addend,
                                      buf);
      switch (rstat)
        {
        case bfd_reloc_ok:
          break;
        default:
        case bfd_reloc_outofrange:
          abort ();
        case bfd_reloc_overflow:
          if (! ((*info->callbacks->reloc_overflow)
                 (info, NULL,
                  (link_order->type == bfd_section_reloc_link_order
                   ? bfd_section_name (abfd, link_order->u.reloc.p->u.section)
                   : link_order->u.reloc.p->u.name),
                  r->howto->name, link_order->u.reloc.p->addend,
                  NULL, NULL, 0)))
            {
              free (buf);
              return FALSE;
            }
          break;
        }
      loc = link_order->offset * bfd_octets_per_byte (abfd);
      ok = bfd_set_section_contents (abfd, sec, buf, loc, size);
      free (buf);
      if (! ok)
        return FALSE;

      r->addend = 0;
    }

  sec->orelocation[sec->reloc_count] = r;
  ++sec->reloc_count;

  return TRUE;
}
\f
/* Allocate a new link_order for a section.  */

struct bfd_link_order *
bfd_new_link_order (bfd *abfd, asection *section)
{
  bfd_size_type amt = sizeof (struct bfd_link_order);
  struct bfd_link_order *new;

  new = bfd_zalloc (abfd, amt);
  if (!new)
    return NULL;

  new->type = bfd_undefined_link_order;

  if (section->map_tail.link_order != NULL)
    section->map_tail.link_order->next = new;
  else
    section->map_head.link_order = new;
  section->map_tail.link_order = new;

  return new;
}

/* Default link order processing routine.  Note that we can not handle
   the reloc_link_order types here, since they depend upon the details
   of how the particular backends generates relocs.  */

bfd_boolean
_bfd_default_link_order (bfd *abfd,
                         struct bfd_link_info *info,
                         asection *sec,
                         struct bfd_link_order *link_order)
{
  switch (link_order->type)
    {
    case bfd_undefined_link_order:
    case bfd_section_reloc_link_order:
    case bfd_symbol_reloc_link_order:
    default:
      abort ();
    case bfd_indirect_link_order:
      return default_indirect_link_order (abfd, info, sec, link_order,
                                          FALSE);
    case bfd_data_link_order:
      return default_data_link_order (abfd, info, sec, link_order);
    }
}

/* Default routine to handle a bfd_data_link_order.  */

static bfd_boolean
default_data_link_order (bfd *abfd,
                         struct bfd_link_info *info ATTRIBUTE_UNUSED,
                         asection *sec,
                         struct bfd_link_order *link_order)
{
  bfd_size_type size;
  size_t fill_size;
  bfd_byte *fill;
  file_ptr loc;
  bfd_boolean result;

  BFD_ASSERT ((sec->flags & SEC_HAS_CONTENTS) != 0);

  size = link_order->size;
  if (size == 0)
    return TRUE;

  fill = link_order->u.data.contents;
  fill_size = link_order->u.data.size;
  if (fill_size != 0 && fill_size < size)
    {
      bfd_byte *p;
      fill = bfd_malloc (size);
      if (fill == NULL)
        return FALSE;
      p = fill;
      if (fill_size == 1)
        memset (p, (int) link_order->u.data.contents[0], (size_t) size);
      else
        {
          do
            {
              memcpy (p, link_order->u.data.contents, fill_size);
              p += fill_size;
              size -= fill_size;
            }
          while (size >= fill_size);
          if (size != 0)
            memcpy (p, link_order->u.data.contents, (size_t) size);
          size = link_order->size;
        }
    }

  loc = link_order->offset * bfd_octets_per_byte (abfd);
  result = bfd_set_section_contents (abfd, sec, fill, loc, size);

  if (fill != link_order->u.data.contents)
    free (fill);
  return result;
}

/* Default routine to handle a bfd_indirect_link_order.  */

static bfd_boolean
default_indirect_link_order (bfd *output_bfd,
                             struct bfd_link_info *info,
                             asection *output_section,
                             struct bfd_link_order *link_order,
                             bfd_boolean generic_linker)
{
  asection *input_section;
  bfd *input_bfd;
  bfd_byte *contents = NULL;
  bfd_byte *new_contents;
  bfd_size_type sec_size;
  file_ptr loc;

  BFD_ASSERT ((output_section->flags & SEC_HAS_CONTENTS) != 0);

  input_section = link_order->u.indirect.section;
  input_bfd = input_section->owner;
  if (input_section->size == 0)
    return TRUE;

  BFD_ASSERT (input_section->output_section == output_section);
  BFD_ASSERT (input_section->output_offset == link_order->offset);
  BFD_ASSERT (input_section->size == link_order->size);

  if (info->relocatable
      && input_section->reloc_count > 0
      && output_section->orelocation == NULL)
    {
      /* Space has not been allocated for the output relocations.
         This can happen when we are called by a specific backend
         because somebody is attempting to link together different
         types of object files.  Handling this case correctly is
         difficult, and sometimes impossible.  */
      (*_bfd_error_handler)
        (_("Attempt to do relocatable link with %s input and %s output"),
         bfd_get_target (input_bfd), bfd_get_target (output_bfd));
      bfd_set_error (bfd_error_wrong_format);
      return FALSE;
    }

  if (! generic_linker)
    {
      asymbol **sympp;
      asymbol **symppend;

      /* Get the canonical symbols.  The generic linker will always
         have retrieved them by this point, but we are being called by
         a specific linker, presumably because we are linking
         different types of object files together.  */
      if (! generic_link_read_symbols (input_bfd))
        return FALSE;

      /* Since we have been called by a specific linker, rather than
         the generic linker, the values of the symbols will not be
         right.  They will be the values as seen in the input file,
         not the values of the final link.  We need to fix them up
         before we can relocate the section.  */
      sympp = _bfd_generic_link_get_symbols (input_bfd);
      symppend = sympp + _bfd_generic_link_get_symcount (input_bfd);
      for (; sympp < symppend; sympp++)
        {
          asymbol *sym;
          struct bfd_link_hash_entry *h;

          sym = *sympp;

          if ((sym->flags & (BSF_INDIRECT
                             | BSF_WARNING
                             | BSF_GLOBAL
                             | BSF_CONSTRUCTOR
                             | BSF_WEAK)) != 0
              || bfd_is_und_section (bfd_get_section (sym))
              || bfd_is_com_section (bfd_get_section (sym))
              || bfd_is_ind_section (bfd_get_section (sym)))
            {
              /* sym->udata may have been set by
                 generic_link_add_symbol_list.  */
              if (sym->udata.p != NULL)
                h = sym->udata.p;
              else if (bfd_is_und_section (bfd_get_section (sym)))
                h = bfd_wrapped_link_hash_lookup (output_bfd, info,
                                                  bfd_asymbol_name (sym),
                                                  FALSE, FALSE, TRUE);
              else
                h = bfd_link_hash_lookup (info->hash,
                                          bfd_asymbol_name (sym),
                                          FALSE, FALSE, TRUE);
              if (h != NULL)
                set_symbol_from_hash (sym, h);
            }
        }
    }

  /* Get and relocate the section contents.  */
  sec_size = (input_section->rawsize > input_section->size
              ? input_section->rawsize
              : input_section->size);
  contents = bfd_malloc (sec_size);
  if (contents == NULL && sec_size != 0)
    goto error_return;
  new_contents = (bfd_get_relocated_section_contents
                  (output_bfd, info, link_order, contents, info->relocatable,
                   _bfd_generic_link_get_symbols (input_bfd)));
  if (!new_contents)
    goto error_return;

  /* Output the section contents.  */
  loc = input_section->output_offset * bfd_octets_per_byte (output_bfd);
  if (! bfd_set_section_contents (output_bfd, output_section,
                                  new_contents, loc, input_section->size))
    goto error_return;

  if (contents != NULL)
    free (contents);
  return TRUE;

 error_return:
  if (contents != NULL)
    free (contents);
  return FALSE;
}

/* A little routine to count the number of relocs in a link_order
   list.  */

unsigned int
_bfd_count_link_order_relocs (struct bfd_link_order *link_order)
{
  register unsigned int c;
  register struct bfd_link_order *l;

  c = 0;
  for (l = link_order; l != NULL; l = l->next)
    {
      if (l->type == bfd_section_reloc_link_order
          || l->type == bfd_symbol_reloc_link_order)
        ++c;
    }

  return c;
}

/*
FUNCTION
        bfd_link_split_section

SYNOPSIS
        bfd_boolean bfd_link_split_section (bfd *abfd, asection *sec);

DESCRIPTION
        Return nonzero if @var{sec} should be split during a
        reloceatable or final link.

.#define bfd_link_split_section(abfd, sec) \
.       BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec))
.

*/

bfd_boolean
_bfd_generic_link_split_section (bfd *abfd ATTRIBUTE_UNUSED,
                                 asection *sec ATTRIBUTE_UNUSED)
{
  return FALSE;
}

/*
FUNCTION
        bfd_section_already_linked

SYNOPSIS
        void bfd_section_already_linked (bfd *abfd, asection *sec);

DESCRIPTION
        Check if @var{sec} has been already linked during a reloceatable
        or final link.

.#define bfd_section_already_linked(abfd, sec) \
.       BFD_SEND (abfd, _section_already_linked, (abfd, sec))
.

*/

/* Sections marked with the SEC_LINK_ONCE flag should only be linked
   once into the output.  This routine checks each section, and
   arrange to discard it if a section of the same name has already
   been linked.  This code assumes that all relevant sections have the 
   SEC_LINK_ONCE flag set; that is, it does not depend solely upon the
   section name.  bfd_section_already_linked is called via
   bfd_map_over_sections.  */

/* The hash table.  */

static struct bfd_hash_table _bfd_section_already_linked_table;

/* Support routines for the hash table used by section_already_linked,
   initialize the table, traverse, lookup, fill in an entry and remove
   the table.  */

void
bfd_section_already_linked_table_traverse
  (bfd_boolean (*func) (struct bfd_section_already_linked_hash_entry *,
                        void *), void *info)
{
  bfd_hash_traverse (&_bfd_section_already_linked_table,
                     (bfd_boolean (*) (struct bfd_hash_entry *,
                                       void *)) func,
                     info);
}

struct bfd_section_already_linked_hash_entry *
bfd_section_already_linked_table_lookup (const char *name)
{
  return ((struct bfd_section_already_linked_hash_entry *)
          bfd_hash_lookup (&_bfd_section_already_linked_table, name,
                           TRUE, FALSE));
}

void
bfd_section_already_linked_table_insert
  (struct bfd_section_already_linked_hash_entry *already_linked_list,
   asection *sec)
{
  struct bfd_section_already_linked *l;

  /* Allocate the memory from the same obstack as the hash table is
     kept in.  */
  l = bfd_hash_allocate (&_bfd_section_already_linked_table, sizeof *l);
  l->sec = sec;
  l->next = already_linked_list->entry;
  already_linked_list->entry = l;
}

static struct bfd_hash_entry *
already_linked_newfunc (struct bfd_hash_entry *entry ATTRIBUTE_UNUSED,
                        struct bfd_hash_table *table,
                        const char *string ATTRIBUTE_UNUSED)
{
  struct bfd_section_already_linked_hash_entry *ret =
    bfd_hash_allocate (table, sizeof *ret);

  ret->entry = NULL;

  return &ret->root;
}

bfd_boolean
bfd_section_already_linked_table_init (void)
{
  return bfd_hash_table_init_n (&_bfd_section_already_linked_table,
                                already_linked_newfunc,
                                sizeof (struct bfd_section_already_linked_hash_entry),
                                42);
}

void
bfd_section_already_linked_table_free (void)
{
  bfd_hash_table_free (&_bfd_section_already_linked_table);
}

/* This is used on non-ELF inputs.  */

void
_bfd_generic_section_already_linked (bfd *abfd, asection *sec)
{
  flagword flags;
  const char *name;
  struct bfd_section_already_linked *l;
  struct bfd_section_already_linked_hash_entry *already_linked_list;

  flags = sec->flags;
  if ((flags & SEC_LINK_ONCE) == 0)
    return;

  /* FIXME: When doing a relocatable link, we may have trouble
     copying relocations in other sections that refer to local symbols
     in the section being discarded.  Those relocations will have to
     be converted somehow; as of this writing I'm not sure that any of
     the backends handle that correctly.

     It is tempting to instead not discard link once sections when
     doing a relocatable link (technically, they should be discarded
     whenever we are building constructors).  However, that fails,
     because the linker winds up combining all the link once sections
     into a single large link once section, which defeats the purpose
     of having link once sections in the first place.  */

  name = bfd_get_section_name (abfd, sec);

  already_linked_list = bfd_section_already_linked_table_lookup (name);

  for (l = already_linked_list->entry; l != NULL; l = l->next)
    {
      bfd_boolean skip = FALSE;
      struct coff_comdat_info *s_comdat
        = bfd_coff_get_comdat_section (abfd, sec);
      struct coff_comdat_info *l_comdat
        = bfd_coff_get_comdat_section (l->sec->owner, l->sec);

      /* We may have 3 different sections on the list: group section,
         comdat section and linkonce section. SEC may be a linkonce or
         comdat section. We always ignore group section. For non-COFF
         inputs, we also ignore comdat section.

         FIXME: Is that safe to match a linkonce section with a comdat
         section for COFF inputs?  */
      if ((l->sec->flags & SEC_GROUP) != 0)
        skip = TRUE;
      else if (bfd_get_flavour (abfd) == bfd_target_coff_flavour)
        {
          if (s_comdat != NULL
              && l_comdat != NULL
              && strcmp (s_comdat->name, l_comdat->name) != 0)
            skip = TRUE;
        }
      else if (l_comdat != NULL)
        skip = TRUE;

      if (!skip)
        {
          /* The section has already been linked.  See if we should
             issue a warning.  */
          switch (flags & SEC_LINK_DUPLICATES)
            {
            default:
              abort ();

            case SEC_LINK_DUPLICATES_DISCARD:
              break;

            case SEC_LINK_DUPLICATES_ONE_ONLY:
              (*_bfd_error_handler)
                (_("%B: warning: ignoring duplicate section `%A'\n"),
                 abfd, sec);
              break;

            case SEC_LINK_DUPLICATES_SAME_CONTENTS:
              /* FIXME: We should really dig out the contents of both
                 sections and memcmp them.  The COFF/PE spec says that
                 the Microsoft linker does not implement this
                 correctly, so I'm not going to bother doing it
                 either.  */
              /* Fall through.  */
            case SEC_LINK_DUPLICATES_SAME_SIZE:
              if (sec->size != l->sec->size)
                (*_bfd_error_handler)
                  (_("%B: warning: duplicate section `%A' has different size\n"),
                   abfd, sec);
              break;
            }

          /* Set the output_section field so that lang_add_section
             does not create a lang_input_section structure for this
             section.  Since there might be a symbol in the section
             being discarded, we must retain a pointer to the section
             which we are really going to use.  */
          sec->output_section = bfd_abs_section_ptr;
          sec->kept_section = l->sec;

          return;
        }
    }

  /* This is the first section with this name.  Record it.  */
  bfd_section_already_linked_table_insert (already_linked_list, sec);
}

/* Convert symbols in excluded output sections to absolute.  */

static bfd_boolean
fix_syms (struct bfd_link_hash_entry *h, void *data)
{
  bfd *obfd = (bfd *) data;

  if (h->type == bfd_link_hash_warning)
    h = h->u.i.link;

  if (h->type == bfd_link_hash_defined
      || h->type == bfd_link_hash_defweak)
    {
      asection *s = h->u.def.section;
      if (s != NULL
          && s->output_section != NULL
          && (s->output_section->flags & SEC_EXCLUDE) != 0
          && bfd_section_removed_from_list (obfd, s->output_section))
        {
          h->u.def.value += s->output_offset + s->output_section->vma;
          h->u.def.section = bfd_abs_section_ptr;
        }
    }

  return TRUE;
}

void
_bfd_fix_excluded_sec_syms (bfd *obfd, struct bfd_link_info *info)
{
  bfd_link_hash_traverse (info->hash, fix_syms, obfd);
}