path: root/ld/ldmain.c

/* Main program of GNU linker.
   Copyright (C) 1991, 92, 93, 94 Free Software Foundation, Inc.
   Written by Steve Chamberlain steve@cygnus.com

This file is part of GLD, the Gnu Linker.

GLD 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, or (at your option)
any later version.

GLD 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 GLD; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


#include "bfd.h"
#include "sysdep.h"
#include <stdio.h>
#include "libiberty.h"
#include "bfdlink.h"

#include "config.h"
#include "ld.h"
#include "ldmain.h"
#include "ldmisc.h"
#include "ldwrite.h"
#include "ldgram.h"
#include "ldexp.h"
#include "ldlang.h"
#include "ldemul.h"
#include "ldlex.h"
#include "ldfile.h"
#include "ldctor.h"

/* Somewhere above, sys/stat.h got included . . . . */
#if !defined(S_ISDIR) && defined(S_IFDIR)
#define	S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
#endif

#include <string.h>

static char *get_emulation PARAMS ((int, char **));
static void set_scripts_dir PARAMS ((void));

/* EXPORTS */

char *default_target;
const char *output_filename = "a.out";

/* Name this program was invoked by.  */
char *program_name;

/* The file that we're creating */
bfd *output_bfd = 0;

/* Set by -G argument, for MIPS ECOFF target.  */
int g_switch_value = 8;

/* Nonzero means print names of input files as processed.  */
boolean trace_files;

/* Nonzero means same, but note open failures, too.  */
boolean trace_file_tries;

/* Nonzero means version number was printed, so exit successfully
   instead of complaining if no input files are given.  */
boolean version_printed;

args_type command_line;

ld_config_type config;

static boolean check_for_scripts_dir PARAMS ((char *dir));
static boolean add_archive_element PARAMS ((struct bfd_link_info *, bfd *,
					    const char *));
static boolean multiple_definition PARAMS ((struct bfd_link_info *,
					    const char *,
					    bfd *, asection *, bfd_vma,
					    bfd *, asection *, bfd_vma));
static boolean multiple_common PARAMS ((struct bfd_link_info *,
					const char *, bfd *,
					enum bfd_link_hash_type, bfd_vma,
					bfd *, enum bfd_link_hash_type,
					bfd_vma));
static boolean add_to_set PARAMS ((struct bfd_link_info *,
				   struct bfd_link_hash_entry *,
				   bfd_reloc_code_real_type,
				   bfd *, asection *, bfd_vma));
static boolean constructor_callback PARAMS ((struct bfd_link_info *,
					     boolean constructor,
					     const char *name,
					     bfd *, asection *, bfd_vma));
static boolean warning_callback PARAMS ((struct bfd_link_info *,
					 const char *));
static boolean undefined_symbol PARAMS ((struct bfd_link_info *,
					 const char *, bfd *,
					 asection *, bfd_vma));
static boolean reloc_overflow PARAMS ((struct bfd_link_info *, const char *,
				       const char *, bfd_vma,
				       bfd *, asection *, bfd_vma));
static boolean reloc_dangerous PARAMS ((struct bfd_link_info *, const char *,
					bfd *, asection *, bfd_vma));
static boolean unattached_reloc PARAMS ((struct bfd_link_info *,
					 const char *, bfd *, asection *,
					 bfd_vma));
static boolean notice_ysym PARAMS ((struct bfd_link_info *, const char *,
				    bfd *, asection *, bfd_vma));

static struct bfd_link_callbacks link_callbacks =
{
  add_archive_element,
  multiple_definition,
  multiple_common,
  add_to_set,
  constructor_callback,
  warning_callback,
  undefined_symbol,
  reloc_overflow,
  reloc_dangerous,
  unattached_reloc,
  notice_ysym
};

struct bfd_link_info link_info;

static void
remove_output ()
{
  if (output_filename) 
    {
      if (output_bfd && output_bfd->iostream)
	fclose((FILE *)(output_bfd->iostream));
      if (delete_output_file_on_failure)
	unlink (output_filename);
    }
}

int
main (argc, argv)
     int argc;
     char **argv;
{
  char *emulation;
  long start_time = get_run_time ();

  program_name = argv[0];
  xmalloc_set_program_name (program_name);

  bfd_init ();

  xatexit (remove_output);

  /* Initialize the data about options.  */
  trace_files = trace_file_tries = version_printed = false;
  config.traditional_format = false;
  config.build_constructors = true;
  config.dynamic_link = false;
  command_line.force_common_definition = false;
  command_line.interpreter = NULL;

  link_info.callbacks = &link_callbacks;
  link_info.relocateable = false;
  link_info.shared = false;
  link_info.strip = strip_none;
  link_info.discard = discard_none;
  link_info.lprefix_len = 1;
  link_info.lprefix = "L";
  link_info.keep_memory = true;
  link_info.input_bfds = NULL;
  link_info.create_object_symbols_section = NULL;
  link_info.hash = NULL;
  link_info.keep_hash = NULL;
  link_info.notice_hash = NULL;

  ldfile_add_arch ("");

  config.make_executable = true;
  force_make_executable = false;
  config.magic_demand_paged = true;
  config.text_read_only = true;
  config.make_executable = true;

  emulation = get_emulation (argc, argv);
  ldemul_choose_mode (emulation);
  default_target = ldemul_choose_target ();
  lang_init ();
  ldemul_before_parse ();
  lang_has_input_file = false;
  parse_args (argc, argv);

  if (link_info.relocateable)
    {
      if (command_line.relax)
	einfo ("%P%F: -relax and -r may not be used together\n");
      if (config.dynamic_link)
	einfo ("%P%F: -r and -call_shared may not be used together\n");
      if (link_info.strip == strip_all)
	einfo ("%P%F: -r and -s may not be used together\n");
      if (link_info.shared)
	einfo ("%P%F: -r and -shared may not be used together\n");
    }

  /* This essentially adds another -L directory so this must be done after
     the -L's in argv have been processed.  */
  set_scripts_dir ();

  if (had_script == false)
    {
      /* Read the emulation's appropriate default script.  */
      int isfile;
      char *s = ldemul_get_script (&isfile);

      if (isfile)
	ldfile_open_command_file (s);
      else
	lex_redirect (s);
      parser_input = input_script;
      yyparse ();
    }

  lang_final ();

  if (lang_has_input_file == false)
    {
      if (version_printed)
	xexit (0);
      einfo ("%P%F: no input files\n");
    }

  if (trace_files)
    {
      info_msg ("%P: mode %s\n", emulation);
    }

  ldemul_after_parse ();


  if (config.map_filename)
    {
      if (strcmp (config.map_filename, "-") == 0)
	{
	  config.map_file = stdout;
	}
      else
	{
	  config.map_file = fopen (config.map_filename, FOPEN_WT);
	  if (config.map_file == (FILE *) NULL)
	    {
	      einfo ("%P%F: cannot open map file %s: %E\n",
		     config.map_filename);
	    }
	}
    }


  lang_process ();

  /* Print error messages for any missing symbols, for any warning
     symbols, and possibly multiple definitions */


  if (config.text_read_only)
    {
      /* Look for a text section and mark the readonly attribute in it */
      asection *found = bfd_get_section_by_name (output_bfd, ".text");

      if (found != (asection *) NULL)
	{
	  found->flags |= SEC_READONLY;
	}
    }

  if (link_info.relocateable)
    output_bfd->flags &= ~EXEC_P;
  else
    output_bfd->flags |= EXEC_P;

  ldwrite ();

  /* Even if we're producing relocateable output, some non-fatal errors should
     be reported in the exit status.  (What non-fatal errors, if any, do we
     want to ignore for relocateable output?)  */

  if (config.make_executable == false && force_make_executable == false)
    {
      if (trace_files == true)
	{
	  einfo ("%P: link errors found, deleting executable `%s'\n",
		 output_filename);
	}

      if (output_bfd->iostream)
	fclose ((FILE *) (output_bfd->iostream));

      unlink (output_filename);
      xexit (1);
    }
  else
    {
      if (! bfd_close (output_bfd))
	einfo ("%F%B: final close failed: %E\n", output_bfd);
    }

  if (config.stats)
    {
      extern char **environ;
      char *lim = (char *) sbrk (0);
      long run_time = get_run_time () - start_time;

      fprintf (stderr, "%s: total time in link: %ld.%06ld\n",
	       program_name, run_time / 1000000, run_time % 1000000);
      fprintf (stderr, "%s: data size %ld\n", program_name,
	       (long) (lim - (char *) &environ));
    }

  /* Prevent remove_output from doing anything, after a successful link.  */
  output_filename = NULL;

  xexit (0);
  return 0;
}

/* We need to find any explicitly given emulation in order to initialize the
   state that's needed by the lex&yacc argument parser (parse_args).  */

static char *
get_emulation (argc, argv)
     int argc;
     char **argv;
{
  char *emulation;
  int i;

  emulation = (char *) getenv (EMULATION_ENVIRON);
  if (emulation == NULL)
    emulation = DEFAULT_EMULATION;

  for (i = 1; i < argc; i++)
    {
      if (!strncmp (argv[i], "-m", 2))
	{
	  if (argv[i][2] == '\0')
	    {
	      /* -m EMUL */
	      if (i < argc - 1)
		{
		  emulation = argv[i + 1];
		  i++;
		}
	      else
		{
		  einfo("%P%F: missing argument to -m\n");
		}
	    }
	  else if (strcmp (argv[i], "-mips1") == 0
		   || strcmp (argv[i], "-mips2") == 0
		   || strcmp (argv[i], "-mips3") == 0)
	    {
	      /* FIXME: The arguments -mips1, -mips2 and -mips3 are
		 passed to the linker by some MIPS compilers.  They
		 generally tell the linker to use a slightly different
		 library path.  Perhaps someday these should be
		 implemented as emulations; until then, we just ignore
		 the arguments and hope that nobody ever creates
		 emulations named ips1, ips2 or ips3.  */
	    }
	  else if (strcmp (argv[i], "-m486") == 0)
	    {
	      /* FIXME: The argument -m486 is passed to the linker on
		 some Linux systems.  Hope that nobody creates an
		 emulation named 486.  */
	    }
	  else
	    {
	      /* -mEMUL */
	      emulation = &argv[i][2];
	    }
	}
    }

  return emulation;
}

/* If directory DIR contains an "ldscripts" subdirectory,
   add DIR to the library search path and return true,
   else return false.  */

static boolean
check_for_scripts_dir (dir)
     char *dir;
{
  size_t dirlen;
  char *buf;
  struct stat s;
  boolean res;

  dirlen = strlen (dir);
  /* sizeof counts the terminating NUL.  */
  buf = (char *) xmalloc (dirlen + sizeof("/ldscripts"));
  sprintf (buf, "%s/ldscripts", dir);

  res = stat (buf, &s) == 0 && S_ISDIR (s.st_mode);
  free (buf);
  if (res)
    ldfile_add_library_path (dir, false);
  return res;
}

/* Set the default directory for finding script files.
   Libraries will be searched for here too, but that's ok.
   We look for the "ldscripts" directory in:

   SCRIPTDIR (passed from Makefile)
   the dir where this program is (for using it from the build tree)
   the dir where this program is/../lib (for installing the tool suite elsewhere) */

static void
set_scripts_dir ()
{
  char *end, *dir;
  size_t dirlen;

  if (check_for_scripts_dir (SCRIPTDIR))
    return;			/* We've been installed normally.  */

  /* Look for "ldscripts" in the dir where our binary is.  */
  end = strrchr (program_name, '/');
  if (end)
    {
      dirlen = end - program_name;
      /* Make a copy of program_name in dir.
	 Leave room for later "/../lib".  */
      dir = (char *) xmalloc (dirlen + 8);
      strncpy (dir, program_name, dirlen);
      dir[dirlen] = '\0';
    }
  else
    {
      dirlen = 1;
      dir = (char *) xmalloc (dirlen + 8);
      strcpy (dir, ".");
    }

  if (check_for_scripts_dir (dir))
    return;			/* Don't free dir.  */

  /* Look for "ldscripts" in <the dir where our binary is>/../lib.  */
  strcpy (dir + dirlen, "/../lib");
  if (check_for_scripts_dir (dir))
    return;

  free (dir);			/* Well, we tried.  */
}

void
add_ysym (name)
     const char *name;
{
  if (link_info.notice_hash == (struct bfd_hash_table *) NULL)
    {
      link_info.notice_hash = ((struct bfd_hash_table *)
			       xmalloc (sizeof (struct bfd_hash_table)));
      if (! bfd_hash_table_init_n (link_info.notice_hash,
				   bfd_hash_newfunc,
				   61))
	einfo ("%P%F: bfd_hash_table_init failed: %E\n");
    }      

  if (bfd_hash_lookup (link_info.notice_hash, name, true, true)
      == (struct bfd_hash_entry *) NULL)
    einfo ("%P%F: bfd_hash_lookup failed: %E\n");
}

/* Handle the -retain-symbols-file option.  */

void
add_keepsyms_file (filename)
     const char *filename;
{
  FILE *file;
  char *buf;
  size_t bufsize;
  int c;

  if (link_info.strip == strip_some)
    einfo ("%X%P: error: duplicate retain-symbols-file\n");

  file = fopen (filename, "r");
  if (file == (FILE *) NULL)
    {
      bfd_set_error (bfd_error_system_call);
      einfo ("%X%P: %s: %E", filename);
      return;
    }

  link_info.keep_hash = ((struct bfd_hash_table *)
			 xmalloc (sizeof (struct bfd_hash_table)));
  if (! bfd_hash_table_init (link_info.keep_hash, bfd_hash_newfunc))
    einfo ("%P%F: bfd_hash_table_init failed: %E\n");

  bufsize = 100;
  buf = (char *) xmalloc (bufsize);

  c = getc (file);
  while (c != EOF)
    {
      while (isspace (c))
	c = getc (file);

      if (c != EOF)
	{
	  size_t len = 0;

	  while (! isspace (c) && c != EOF)
	    {
	      buf[len] = c;
	      ++len;
	      if (len >= bufsize)
		{
		  bufsize *= 2;
		  buf = xrealloc (buf, bufsize);
		}
	      c = getc (file);
	    }

	  buf[len] = '\0';

	  if (bfd_hash_lookup (link_info.keep_hash, buf, true, true)
	      == (struct bfd_hash_entry *) NULL)
	    einfo ("%P%F: bfd_hash_lookup for insertion failed: %E");
	}
    }

  if (link_info.strip != strip_none)
    einfo ("%P: `-retain-symbols-file' overrides `-s' and `-S'\n");

  link_info.strip = strip_some;
}

/* Callbacks from the BFD linker routines.  */

/* This is called when BFD has decided to include an archive member in
   a link.  */

/*ARGSUSED*/
static boolean
add_archive_element (info, abfd, name)
     struct bfd_link_info *info;
     bfd *abfd;
     const char *name;
{
  lang_input_statement_type *input;

  input = ((lang_input_statement_type *)
	   xmalloc ((bfd_size_type) sizeof (lang_input_statement_type)));
  input->filename = abfd->filename;
  input->local_sym_name = abfd->filename;
  input->the_bfd = abfd;
  input->asymbols = NULL;
  input->next = NULL;
  input->just_syms_flag = false;
  input->loaded = false;
  input->search_dirs_flag = false;

  /* FIXME: The following fields are not set: header.next,
     header.type, closed, passive_position, symbol_count,
     next_real_file, is_archive, target, real, common_section,
     common_output_section, complained.  This bit of code is from the
     old decode_library_subfile function.  I don't know whether any of
     those fields matters.  */

  ldlang_add_file (input);

  if (config.map_file != (FILE *) NULL)
    minfo ("%s needed due to %T\n", abfd->filename, name);

  if (trace_files || trace_file_tries)
    info_msg ("%I\n", input);

  return true;
}

/* This is called when BFD has discovered a symbol which is defined
   multiple times.  */

/*ARGSUSED*/
static boolean
multiple_definition (info, name, obfd, osec, oval, nbfd, nsec, nval)
     struct bfd_link_info *info;
     const char *name;
     bfd *obfd;
     asection *osec;
     bfd_vma oval;
     bfd *nbfd;
     asection *nsec;
     bfd_vma nval;
{
  einfo ("%X%C: multiple definition of `%T'\n",
	 nbfd, nsec, nval, name);
  if (obfd != (bfd *) NULL)
    einfo ("%C: first defined here\n", obfd, osec, oval);
  return true;
}

/* This is called when there is a definition of a common symbol, or
   when a common symbol is found for a symbol that is already defined,
   or when two common symbols are found.  We only do something if
   -warn-common was used.  */

/*ARGSUSED*/
static boolean
multiple_common (info, name, obfd, otype, osize, nbfd, ntype, nsize)
     struct bfd_link_info *info;
     const char *name;
     bfd *obfd;
     enum bfd_link_hash_type otype;
     bfd_vma osize;
     bfd *nbfd;
     enum bfd_link_hash_type ntype;
     bfd_vma nsize;
{
  if (! config.warn_common)
    return true;

  if (ntype == bfd_link_hash_defined)
    {
      ASSERT (otype == bfd_link_hash_common);
      einfo ("%B: warning: definition of `%T' overriding common\n",
	     nbfd, name);
      einfo ("%B: warning: common is here\n", obfd);
    }
  else if (otype == bfd_link_hash_defined)
    {
      ASSERT (ntype == bfd_link_hash_common);
      einfo ("%B: warning: common of `%T' overridden by definition\n",
	     nbfd, name);
      einfo ("%B: warning: defined here\n", obfd);
    }
  else
    {
      ASSERT (otype == bfd_link_hash_common && ntype == bfd_link_hash_common);
      if (osize > nsize)
	{
	  einfo ("%B: warning: common of `%T' overridden by larger common\n",
		 nbfd, name);
	  einfo ("%B: warning: larger common is here\n", obfd);
	}
      else if (nsize > osize)
	{
	  einfo ("%B: warning: common of `%T' overriding smaller common\n",
		 nbfd, name);
	  einfo ("%B: warning: smaller common is here\n", obfd);
	}
      else
	{
	  einfo ("%B: warning: multiple common of `%T'\n", nbfd, name);
	  einfo ("%B: warning: previous common is here\n", obfd);
	}
    }

  return true;
}

/* This is called when BFD has discovered a set element.  H is the
   entry in the linker hash table for the set.  SECTION and VALUE
   represent a value which should be added to the set.  */

/*ARGSUSED*/
static boolean
add_to_set (info, h, reloc, abfd, section, value)
     struct bfd_link_info *info;
     struct bfd_link_hash_entry *h;
     bfd_reloc_code_real_type reloc;
     bfd *abfd;
     asection *section;
     bfd_vma value;
{
  if (! config.build_constructors)
    return true;

  ldctor_add_set_entry (h, reloc, section, value);

  if (h->type == bfd_link_hash_new)
    {
      h->type = bfd_link_hash_undefined;
      h->u.undef.abfd = abfd;
      /* We don't call bfd_link_add_undef to add this to the list of
	 undefined symbols because we are going to define it
	 ourselves.  */
    }

  return true;
}

/* This is called when BFD has discovered a constructor.  This is only
   called for some object file formats--those which do not handle
   constructors in some more clever fashion.  This is similar to
   adding an element to a set, but less general.  */

static boolean
constructor_callback (info, constructor, name, abfd, section, value)
     struct bfd_link_info *info;
     boolean constructor;
     const char *name;
     bfd *abfd;
     asection *section;
     bfd_vma value;
{
  char *set_name;
  char *s;
  struct bfd_link_hash_entry *h;

  if (! config.build_constructors)
    return true;

  /* Ensure that BFD_RELOC_CTOR exists now, so that we can give a
     useful error message.  */
  if (bfd_reloc_type_lookup (output_bfd, BFD_RELOC_CTOR) == NULL)
    einfo ("%P%F: BFD backend error: BFD_RELOC_CTOR unsupported");

  set_name = (char *) alloca (1 + sizeof "__CTOR_LIST__");
  s = set_name;
  if (bfd_get_symbol_leading_char (abfd) != '\0')
    *s++ = bfd_get_symbol_leading_char (abfd);
  if (constructor)
    strcpy (s, "__CTOR_LIST__");
  else
    strcpy (s, "__DTOR_LIST__");

  if (config.map_file != (FILE *) NULL)
    fprintf (config.map_file,
	     "Adding %s to constructor/destructor set %s\n", name, set_name);

  h = bfd_link_hash_lookup (info->hash, set_name, true, true, true);
  if (h == (struct bfd_link_hash_entry *) NULL)
    einfo ("%P%F: bfd_link_hash_lookup failed: %E");
  if (h->type == bfd_link_hash_new)
    {
      h->type = bfd_link_hash_undefined;
      h->u.undef.abfd = abfd;
      /* We don't call bfd_link_add_undef to add this to the list of
	 undefined symbols because we are going to define it
	 ourselves.  */
    }

  ldctor_add_set_entry (h, BFD_RELOC_CTOR, section, value);
  return true;
}

/* This is called when there is a reference to a warning symbol.  */

/*ARGSUSED*/
static boolean
warning_callback (info, warning)
     struct bfd_link_info *info;
     const char *warning;
{
  einfo ("%P: %s\n", warning);
  return true;
}

/* This is called when an undefined symbol is found.  */

/*ARGSUSED*/
static boolean
undefined_symbol (info, name, abfd, section, address)
     struct bfd_link_info *info;
     const char *name;
     bfd *abfd;
     asection *section;
     bfd_vma address;
{
  static char *error_name;
  static unsigned int error_count;

#define MAX_ERRORS_IN_A_ROW 5

  /* We never print more than a reasonable number of errors in a row
     for a single symbol.  */
  if (error_name != (char *) NULL
      && strcmp (name, error_name) == 0)
    ++error_count;
  else
    {
      error_count = 0;
      if (error_name != (char *) NULL)
	free (error_name);
      error_name = buystring (name);
    }

  if (error_count < MAX_ERRORS_IN_A_ROW)
    einfo ("%X%C: undefined reference to `%T'\n",
	   abfd, section, address, name);
  else if (error_count == MAX_ERRORS_IN_A_ROW)
    einfo ("%C: more undefined references to `%T' follow\n",
	   abfd, section, address, name);

  return true;
}

/* This is called when a reloc overflows.  */

/*ARGSUSED*/
static boolean
reloc_overflow (info, name, reloc_name, addend, abfd, section, address)
     struct bfd_link_info *info;
     const char *name;
     const char *reloc_name;
     bfd_vma addend;
     bfd *abfd;
     asection *section;
     bfd_vma address;
{
  if (abfd == (bfd *) NULL)
    einfo ("%P%X: generated");
  else
    einfo ("%X%C:", abfd, section, address);
  einfo (" relocation truncated to fit: %s %T", reloc_name, name);
  if (addend != 0)
    einfo ("+%v", addend);
  einfo ("\n");
  return true;
}

/* This is called when a dangerous relocation is made.  */

/*ARGSUSED*/
static boolean
reloc_dangerous (info, message, abfd, section, address)
     struct bfd_link_info *info;
     const char *message;
     bfd *abfd;
     asection *section;
     bfd_vma address;
{
  if (abfd == (bfd *) NULL)
    einfo ("%P%X: generated");
  else
    einfo ("%X%C:", abfd, section, address);
  einfo ("dangerous relocation: %s\n", message);
  return true;
}

/* This is called when a reloc is being generated attached to a symbol
   that is not being output.  */

/*ARGSUSED*/
static boolean
unattached_reloc (info, name, abfd, section, address)
     struct bfd_link_info *info;
     const char *name;
     bfd *abfd;
     asection *section;
     bfd_vma address;
{
  if (abfd == (bfd *) NULL)
    einfo ("%P%X: generated");
  else
    einfo ("%X%C:", abfd, section, address);
  einfo (" reloc refers to symbol `%T' which is not being output\n", name);
  return true;
}

/* This is called when a symbol in notice_hash is found.  Symbols are
   put in notice_hash using the -y option.  */

/*ARGSUSED*/
static boolean
notice_ysym (info, name, abfd, section, value)
     struct bfd_link_info *info;
     const char *name;
     bfd *abfd;
     asection *section;
     bfd_vma value;
{
  einfo ("%B: %s %s\n", abfd,
	 section != &bfd_und_section ? "definition of" : "reference to",
	 name);
  return true;
}