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/* linker.c -- BFD linker routines

   Copyright (C) 1993-2015 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 3 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 "sysdep.h"

#include "bfd.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 <> structure (defined in

	<>) 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 <>, and use the

	header file <>.  As of this writing, the only back

	ends which have implemented versions of these routines are

	a.out (in <>) and ECOFF (in <>).  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 <> described in

	<>.  @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 <>.  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 <>.  The a.out linker

	hash table is created by the function

	<>; 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

	<>.

@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 <

	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 output bfd

	xvec 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 <> for an example of how to

	check the output bfd 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

	<> to read the symbols.  The point of

	providing this routine is to avoid the overhead of converting

	the symbols into generic <> 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 <> or

	<>.  The section is a section in the object

	file, or something like <> for an undefined

	symbol or <> 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

	<> field of the <> 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

	<>, and most of the interesting

	work is in <>.  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

	<> linker callback, and it must add the

	symbols from the object file to the linker hash table.  (The

	callback may in fact indicate that a replacement BFD should be

	used, in which case the symbols from that BFD should be added

	to the linker hash table instead.)

@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.

	<<_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.  If the element is to

	be included, the <> linker callback

	routine must be called with the element as an argument, and

	the element's 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 <> as the function

	argument. <> calls

	<>.  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 <> callback and then

	<> calls

	<> to actually add the symbols to the

	linker hash table - possibly those of a substitute BFD, if the

	<> callback avails itself of that option.

	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 <> 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 <>.

@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 <> field of the <> structure

	will point to a list of all the input files included in the

	link.  These files are linked through the <> field

	of the <> structure.

	Each section in the output file will have a list of

	<> structures attached to the <>

	field (the <> structure is defined in

	<>).  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

	<> structures attached to each section of the

	output file.  Each <> 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 <>).

	For efficiency, a <> of type

	<> whose associated section belongs

	to a BFD of the same format as the output BFD must be handled

	specially.  This type of <> 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 <> argument

	which describes the relocation to perform.  These functions

	are defined in <>.

	The a.out function which handles reading, relocating, and

	writing section contents is <>.  The

	actual relocation is done in <>

	and <>.

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 <> and <> fields of the

	<> 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 <> structures, or it may be

	done by stepping through the <> 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 <> field of the <> structure

	controls which symbols are written out.  The possible values

	are listed in <>.  If the value is <>,

	then the <> field of the <>

	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 <> field of the <> structure

	permits local symbols to be written out, the <> field

	is used to further controls which local symbols are included

	in the output file.  If the value is <>, then all

	local symbols which begin with a certain prefix are discarded;

	this is controlled by the <> entry point.

	The a.out backend handles symbols by calling

	<> on each input BFD and then

	traversing the global hash table with the function

	<>.  It builds a string table

	while writing out the symbols, which is written to the output

	file at the end of <>.

*/

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 *, struct bfd_link_hash_entry *, const char *,

   bfd_boolean *);

static bfd_boolean generic_link_check_archive_element_collect

  (bfd *, struct bfd_link_info *, struct bfd_link_hash_entry *, const char *,

   bfd_boolean *);

static bfd_boolean generic_link_check_archive_element

  (bfd *, struct bfd_link_info *, struct bfd_link_hash_entry *, const char *,

   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 = (struct bfd_hash_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.  */

      memset ((char *) &h->root + sizeof (h->root), 0,

	      sizeof (*h) - sizeof (h->root));

    }

  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 ATTRIBUTE_UNUSED,

   struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *,

				      struct bfd_hash_table *,

				      const char *),

   unsigned int entsize)

{

  bfd_boolean ret;

  BFD_ASSERT (!abfd->is_linker_output && !abfd->link.hash);

  table->undefs = NULL;

  table->undefs_tail = NULL;

  table->type = bfd_link_generic_hash_table;

  ret = bfd_hash_table_init (&table->table, newfunc, entsize);

  if (ret)

    {

      /* Arrange for destruction of this hash table on closing ABFD.  */

      table->hash_table_free = _bfd_generic_link_hash_table_free;

      abfd->link.hash = table;

      abfd->is_linker_output = TRUE;

    }

  return ret;

}

/* 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 = (char *) 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  REAL

#define REAL "__real_"

      if (*l == '_'

	  && CONST_STRNEQ (l, REAL)

	  && 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 = (char *) 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);

}

/* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"

   and the remainder is found in wrap_hash, return the real symbol.  */

struct bfd_link_hash_entry *

unwrap_hash_lookup (struct bfd_link_info *info,

		    bfd *input_bfd,

		    struct bfd_link_hash_entry *h)

{

  const char *l = h->root.string;

  if (*l == bfd_get_symbol_leading_char (input_bfd)

      || *l == info->wrap_char)

    ++l;

  if (CONST_STRNEQ (l, WRAP))

    {

      l += sizeof WRAP - 1;

      if (bfd_hash_lookup (info->wrap_hash, l, FALSE, FALSE) != NULL)

	{

	  char save = 0;

	  if (l - (sizeof WRAP - 1) != h->root.string)

	    {

	      --l;

	      save = *l;

	      *(char *) l = *h->root.string;

	    }

	  h = bfd_link_hash_lookup (info->hash, l, FALSE, FALSE, FALSE);

	  if (save)

	    *(char *) l = save;

	}

    }

  return h;

}

#undef WRAP

/* Traverse a generic link hash table.  Differs from bfd_hash_traverse

   in the treatment of warning symbols.  When warning symbols are

   created they replace the real symbol, so you don't get to see the

   real symbol in a bfd_hash_travere.  This traversal calls func with

   the real symbol.  */

void

bfd_link_hash_traverse

  (struct bfd_link_hash_table *htab,

   bfd_boolean (*func) (struct bfd_link_hash_entry *, void *),

   void *info)

{

  unsigned int i;

  htab->table.frozen = 1;

  for (i = 0; i < htab->table.size; i++)

    {

      struct bfd_link_hash_entry *p;

      p = (struct bfd_link_hash_entry *) htab->table.table[i];

      for (; p != NULL; p = (struct bfd_link_hash_entry *) p->root.next)

	if (!(*func) (p->type == bfd_link_hash_warning ? p->u.i.link : p, info))

	  goto out;

    }

 out:

  htab->table.frozen = 0;

}

/* 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;

    }

}

/* 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 = (struct bfd_hash_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 = (struct generic_link_hash_table *) 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 (bfd *obfd)

{

  struct generic_link_hash_table *ret;

  BFD_ASSERT (obfd->is_linker_output && obfd->link.hash);

  ret = (struct generic_link_hash_table *) obfd->link.hash;

  bfd_hash_table_free (&ret->root.table);

  free (ret);

  obfd->link.hash = NULL;

  obfd->is_linker_output = FALSE;

}

/* 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.  */

bfd_boolean

bfd_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) = (struct bfd_symbol **) 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;

}

/* 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->sec_info_type = SEC_INFO_TYPE_JUST_SYMS;

  sec->output_section = bfd_abs_section_ptr;

  sec->output_offset = sec->vma;

}

/* Copy the symbol type and other attributes for a linker script

   assignment from HSRC to HDEST.

   The default implementation does nothing.  */

void

_bfd_generic_copy_link_hash_symbol_type (bfd *abfd ATTRIBUTE_UNUSED,

    struct bfd_link_hash_entry *hdest ATTRIBUTE_UNUSED,

    struct bfd_link_hash_entry *hsrc ATTRIBUTE_UNUSED)

{

}

/* 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 (!bfd_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);

}

/* 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 archive symbol

   table for symbols that are undefined or common in the linker global

   symbol hash table.  When one is found, the CHECKFN argument is used

   to see if an object file should be included.  This allows targets

   to customize common symbol behaviour.  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 must notice

   if the callback indicates a substitute BFD, and arrange to add

   those symbols instead if it does so.  CHECKFN should only return

   FALSE if some sort of error occurs.  */

bfd_boolean

_bfd_generic_link_add_archive_symbols

  (bfd *abfd,

   struct bfd_link_info *info,

   bfd_boolean (*checkfn) (bfd *, struct bfd_link_info *,

			   struct bfd_link_hash_entry *, const char *,

			   bfd_boolean *))

{

  bfd_boolean loop;

  bfd_size_type amt;

  unsigned char *included;

  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;

    }

  amt = bfd_ardata (abfd)->symdef_count;

  if (amt == 0)

    return TRUE;

  amt *= sizeof (*included);

  included = (unsigned char *) bfd_zmalloc (amt);

  if (included == NULL)

    return FALSE;

  do

    {

      carsym *arsyms;

      carsym *arsym_end;

      carsym *arsym;

      unsigned int indx;

      file_ptr last_ar_offset = -1;

      bfd_boolean needed = FALSE;

      bfd *element = NULL;

      loop = FALSE;

  arsyms = bfd_ardata (abfd)->symdefs;

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

  for (arsym = arsyms, indx = 0; arsym < arsym_end; arsym++, indx++)

    {

      struct bfd_link_hash_entry *h;

	  struct bfd_link_hash_entry *undefs_tail;

	  if (included[indx])

	    continue;

	  if (needed && arsym->file_offset == last_ar_offset)

	{

	      included[indx] = 1;

	  continue;

	}

	  h = bfd_link_hash_lookup (info->hash, arsym->name,

				    FALSE, FALSE, TRUE);

	  if (h == NULL

	      && info->pei386_auto_import

	      && CONST_STRNEQ (arsym->name, "__imp_"))

	    h = bfd_link_hash_lookup (info->hash, arsym->name + 6,

				      FALSE, FALSE, TRUE);

	  if (h == NULL)

	      continue;

	  if (h->type != bfd_link_hash_undefined

	      && h->type != bfd_link_hash_common)

	    {

	      if (h->type != bfd_link_hash_undefweak)

		/* Symbol must be defined.  Don't check it again.  */

		included[indx] = 1;

	    continue;

	    }

	  if (last_ar_offset != arsym->file_offset)

	    {

	      last_ar_offset = arsym->file_offset;

	      element = _bfd_get_elt_at_filepos (abfd, last_ar_offset);

	      if (element == NULL

		  || !bfd_check_format (element, bfd_object))

		goto error_return;

	    }

	  undefs_tail = info->hash->undefs_tail;

	  /* CHECKFN will see if this element should be included, and

	     go ahead and include it if appropriate.  */

	  if (! (*checkfn) (element, info, h, arsym->name, &needed))

	    goto error_return;

	  if (needed)

	    {

	      unsigned int mark;

	      /* Look backward to mark all symbols from this object file

		 which we have already seen in this pass.  */

	      mark = indx;

	      do

		{

		  included[mark] = 1;

		  if (mark == 0)

		    break;

		  --mark;

	    }

	      while (arsyms[mark].file_offset == last_ar_offset);

	      if (undefs_tail != info->hash->undefs_tail)

		loop = TRUE;

	}

    }

    } while (loop);

  free (included);

  return TRUE;

 error_return:

  free (included);

  return FALSE;

}

/* 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,

					       struct bfd_link_hash_entry *h,

					       const char *name,

					       bfd_boolean *pneeded)

{

  return generic_link_check_archive_element (abfd, info, h, name, 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,

					    struct bfd_link_hash_entry *h,

					    const char *name,

					    bfd_boolean *pneeded)

{

  return generic_link_check_archive_element (abfd, info, h, name, 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,

				    struct bfd_link_hash_entry *h,

				    const char *name ATTRIBUTE_UNUSED,

				    bfd_boolean *pneeded,

				    bfd_boolean collect)

{

  asymbol **pp, **ppend;

  *pneeded = FALSE;

  if (!bfd_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;

      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)