text: /* opncls.c -- open and close a BFD.
     Copyright 1990-2013 Free Software Foundation, Inc.
  
     Written by 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 "objalloc.h"
  #include "libbfd.h"
  #include "libiberty.h"
  
  #ifndef S_IXUSR
  #define S_IXUSR 0100	/* Execute by owner.  */
  #endif
  #ifndef S_IXGRP
  #define S_IXGRP 0010	/* Execute by group.  */
  #endif
  #ifndef S_IXOTH
  #define S_IXOTH 0001	/* Execute by others.  */
  #endif
  
  /* Counters used to initialize the bfd identifier.  */
  
  static unsigned int bfd_id_counter = 0;
  static unsigned int bfd_reserved_id_counter = 0;
  
  /*
  CODE_FRAGMENT
  .{* Set to N to open the next N BFDs using an alternate id space.  *}
  .extern unsigned int bfd_use_reserved_id;
  */
  unsigned int bfd_use_reserved_id = 0;
  
  /* fdopen is a loser -- we should use stdio exclusively.  Unfortunately
     if we do that we can't use fcntl.  */
  
  /* Return a new BFD.  All BFD's are allocated through this routine.  */
  
  bfd *
  _bfd_new_bfd (void)
  {
    bfd *nbfd;
  
    nbfd = (bfd *) bfd_zmalloc (sizeof (bfd));
    if (nbfd == NULL)
      return NULL;
  
    if (bfd_use_reserved_id)
      {
        nbfd->id = --bfd_reserved_id_counter;
        --bfd_use_reserved_id;
      }
    else
      nbfd->id = bfd_id_counter++;
  
    nbfd->memory = objalloc_create ();
    if (nbfd->memory == NULL)
      {
        bfd_set_error (bfd_error_no_memory);
        free (nbfd);
        return NULL;
      }
  
    nbfd->arch_info = &bfd_default_arch_struct;
  
    nbfd->direction = no_direction;
    nbfd->iostream = NULL;
    nbfd->where = 0;
    if (!bfd_hash_table_init_n (& nbfd->section_htab, bfd_section_hash_newfunc,
  			      sizeof (struct section_hash_entry), 13))
      {
        free (nbfd);
        return NULL;
      }
    nbfd->sections = NULL;
    nbfd->section_last = NULL;
    nbfd->format = bfd_unknown;
    nbfd->my_archive = NULL;
    nbfd->origin = 0;
    nbfd->opened_once = FALSE;
    nbfd->output_has_begun = FALSE;
    nbfd->section_count = 0;
    nbfd->usrdata = NULL;
    nbfd->cacheable = FALSE;
    nbfd->flags = BFD_NO_FLAGS;
    nbfd->mtime_set = FALSE;
  
    return nbfd;
  }
  
  static const struct bfd_iovec opncls_iovec;
  
  /* Allocate a new BFD as a member of archive OBFD.  */
  
  bfd *
  _bfd_new_bfd_contained_in (bfd *obfd)
  {
    bfd *nbfd;
  
    nbfd = _bfd_new_bfd ();
    if (nbfd == NULL)
      return NULL;
    nbfd->xvec = obfd->xvec;
    nbfd->iovec = obfd->iovec;
    if (obfd->iovec == &opncls_iovec)
      nbfd->iostream = obfd->iostream;
    nbfd->my_archive = obfd;
    nbfd->direction = read_direction;
    nbfd->target_defaulted = obfd->target_defaulted;
    return nbfd;
  }
  
  /* Delete a BFD.  */
  
  static void
  _bfd_delete_bfd (bfd *abfd)
  {
    if (abfd->memory)
      {
        bfd_hash_table_free (&abfd->section_htab);
        objalloc_free ((struct objalloc *) abfd->memory);
      }
  
    free (abfd->arelt_data);
    free (abfd);
  }
  
  /* Free objalloc memory.  */
  
  bfd_boolean
  _bfd_free_cached_info (bfd *abfd)
  {
    if (abfd->memory)
      {
        bfd_hash_table_free (&abfd->section_htab);
        objalloc_free ((struct objalloc *) abfd->memory);
  
        abfd->sections = NULL;
        abfd->section_last = NULL;
        abfd->outsymbols = NULL;
        abfd->tdata.any = NULL;
        abfd->usrdata = NULL;
        abfd->memory = NULL;
      }
  
    return TRUE;
  }
  
  /*
  SECTION
  	Opening and closing BFDs
  
  SUBSECTION
  	Functions for opening and closing
  */
  
  /*
  FUNCTION
  	bfd_fopen
  
  SYNOPSIS
  	bfd *bfd_fopen (const char *filename, const char *target,
                          const char *mode, int fd);
  
  DESCRIPTION
  	Open the file @var{filename} with the target @var{target}.
  	Return a pointer to the created BFD.  If @var{fd} is not -1,
  	then <<fdopen>> is used to open the file; otherwise, <<fopen>>
  	is used.  @var{mode} is passed directly to <<fopen>> or
  	<<fdopen>>.
  
  	Calls <<bfd_find_target>>, so @var{target} is interpreted as by
  	that function.
  
  	The new BFD is marked as cacheable iff @var{fd} is -1.
  
  	If <<NULL>> is returned then an error has occured.   Possible errors
  	are <<bfd_error_no_memory>>, <<bfd_error_invalid_target>> or
  	<<system_call>> error.
  
  	On error, @var{fd} is always closed.
  */
  
  bfd *
  bfd_fopen (const char *filename, const char *target, const char *mode, int fd)
  {
    bfd *nbfd;
    const bfd_target *target_vec;
  
    nbfd = _bfd_new_bfd ();
    if (nbfd == NULL)
      {
        if (fd != -1)
  	close (fd);
        return NULL;
      }
  
    target_vec = bfd_find_target (target, nbfd);
    if (target_vec == NULL)
      {
        if (fd != -1)
  	close (fd);
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
  
  #ifdef HAVE_FDOPEN
    if (fd != -1)
      nbfd->iostream = fdopen (fd, mode);
    else
  #endif
      nbfd->iostream = real_fopen (filename, mode);
    if (nbfd->iostream == NULL)
      {
        bfd_set_error (bfd_error_system_call);
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
  
    /* OK, put everything where it belongs.  */
    nbfd->filename = filename;
  
    /* Figure out whether the user is opening the file for reading,
       writing, or both, by looking at the MODE argument.  */
    if ((mode[0] == 'r' || mode[0] == 'w' || mode[0] == 'a')
        && mode[1] == '+')
      nbfd->direction = both_direction;
    else if (mode[0] == 'r')
      nbfd->direction = read_direction;
    else
      nbfd->direction = write_direction;
  
    if (! bfd_cache_init (nbfd))
      {
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
    nbfd->opened_once = TRUE;
  
    /* If we opened the file by name, mark it cacheable; we can close it
       and reopen it later.  However, if a file descriptor was provided,
       then it may have been opened with special flags that make it
       unsafe to close and reopen the file.  */
    if (fd == -1)
      (void) bfd_set_cacheable (nbfd, TRUE);
  
    return nbfd;
  }
  
  /*
  FUNCTION
  	bfd_openr
  
  SYNOPSIS
  	bfd *bfd_openr (const char *filename, const char *target);
  
  DESCRIPTION
  	Open the file @var{filename} (using <<fopen>>) with the target
  	@var{target}.  Return a pointer to the created BFD.
  
  	Calls <<bfd_find_target>>, so @var{target} is interpreted as by
  	that function.
  
  	If <<NULL>> is returned then an error has occured.   Possible errors
  	are <<bfd_error_no_memory>>, <<bfd_error_invalid_target>> or
  	<<system_call>> error.
  */
  
  bfd *
  bfd_openr (const char *filename, const char *target)
  {
    return bfd_fopen (filename, target, FOPEN_RB, -1);
  }
  
  /* Don't try to `optimize' this function:
  
     o - We lock using stack space so that interrupting the locking
         won't cause a storage leak.
     o - We open the file stream last, since we don't want to have to
         close it if anything goes wrong.  Closing the stream means closing
         the file descriptor too, even though we didn't open it.  */
  /*
  FUNCTION
  	bfd_fdopenr
  
  SYNOPSIS
  	bfd *bfd_fdopenr (const char *filename, const char *target, int fd);
  
  DESCRIPTION
  	<<bfd_fdopenr>> is to <<bfd_fopenr>> much like <<fdopen>> is to
  	<<fopen>>.  It opens a BFD on a file already described by the
  	@var{fd} supplied.
  
  	When the file is later <<bfd_close>>d, the file descriptor will
  	be closed.  If the caller desires that this file descriptor be
  	cached by BFD (opened as needed, closed as needed to free
  	descriptors for other opens), with the supplied @var{fd} used as
  	an initial file descriptor (but subject to closure at any time),
  	call bfd_set_cacheable(bfd, 1) on the returned BFD.  The default
  	is to assume no caching; the file descriptor will remain open
  	until <<bfd_close>>, and will not be affected by BFD operations
  	on other files.
  
  	Possible errors are <<bfd_error_no_memory>>,
  	<<bfd_error_invalid_target>> and <<bfd_error_system_call>>.
  
  	On error, @var{fd} is closed.
  */
  
  bfd *
  bfd_fdopenr (const char *filename, const char *target, int fd)
  {
    const char *mode;
  #if defined(HAVE_FCNTL) && defined(F_GETFL)
    int fdflags;
  #endif
  
  #if ! defined(HAVE_FCNTL) || ! defined(F_GETFL)
    mode = FOPEN_RUB; /* Assume full access.  */
  #else
    fdflags = fcntl (fd, F_GETFL, NULL);
    if (fdflags == -1)
      {
        int save = errno;
  
        close (fd);
        errno = save;
        bfd_set_error (bfd_error_system_call);
        return NULL;
      }
  
    /* (O_ACCMODE) parens are to avoid Ultrix header file bug.  */
    switch (fdflags & (O_ACCMODE))
      {
      case O_RDONLY: mode = FOPEN_RB; break;
      case O_WRONLY: mode = FOPEN_RUB; break;
      case O_RDWR:   mode = FOPEN_RUB; break;
      default: abort ();
      }
  #endif
  
    return bfd_fopen (filename, target, mode, fd);
  }
  
  /*
  FUNCTION
  	bfd_openstreamr
  
  SYNOPSIS
  	bfd *bfd_openstreamr (const char *, const char *, void *);
  
  DESCRIPTION
  
  	Open a BFD for read access on an existing stdio stream.  When
  	the BFD is passed to <<bfd_close>>, the stream will be closed.
  */
  
  bfd *
  bfd_openstreamr (const char *filename, const char *target, void *streamarg)
  {
    FILE *stream = (FILE *) streamarg;
    bfd *nbfd;
    const bfd_target *target_vec;
  
    nbfd = _bfd_new_bfd ();
    if (nbfd == NULL)
      return NULL;
  
    target_vec = bfd_find_target (target, nbfd);
    if (target_vec == NULL)
      {
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
  
    nbfd->iostream = stream;
    nbfd->filename = filename;
    nbfd->direction = read_direction;
  
    if (! bfd_cache_init (nbfd))
      {
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
  
    return nbfd;
  }
  
  /*
  FUNCTION
  	bfd_openr_iovec
  
  SYNOPSIS
          bfd *bfd_openr_iovec (const char *filename, const char *target,
                                void *(*open_func) (struct bfd *nbfd,
                                                    void *open_closure),
                                void *open_closure,
                                file_ptr (*pread_func) (struct bfd *nbfd,
                                                        void *stream,
                                                        void *buf,
                                                        file_ptr nbytes,
                                                        file_ptr offset),
                                int (*close_func) (struct bfd *nbfd,
                                                   void *stream),
  			      int (*stat_func) (struct bfd *abfd,
  					        void *stream,
  					        struct stat *sb));
  
  DESCRIPTION
  
          Create and return a BFD backed by a read-only @var{stream}.
          The @var{stream} is created using @var{open_func}, accessed using
          @var{pread_func} and destroyed using @var{close_func}.
  
  	Calls <<bfd_find_target>>, so @var{target} is interpreted as by
  	that function.
  
  	Calls @var{open_func} (which can call <<bfd_zalloc>> and
  	<<bfd_get_filename>>) to obtain the read-only stream backing
  	the BFD.  @var{open_func} either succeeds returning the
  	non-<<NULL>> @var{stream}, or fails returning <<NULL>>
  	(setting <<bfd_error>>).
  
  	Calls @var{pread_func} to request @var{nbytes} of data from
  	@var{stream} starting at @var{offset} (e.g., via a call to
  	<<bfd_read>>).  @var{pread_func} either succeeds returning the
  	number of bytes read (which can be less than @var{nbytes} when
  	end-of-file), or fails returning -1 (setting <<bfd_error>>).
  
  	Calls @var{close_func} when the BFD is later closed using
  	<<bfd_close>>.  @var{close_func} either succeeds returning 0, or
  	fails returning -1 (setting <<bfd_error>>).
  
  	Calls @var{stat_func} to fill in a stat structure for bfd_stat,
  	bfd_get_size, and bfd_get_mtime calls.  @var{stat_func} returns 0
  	on success, or returns -1 on failure (setting <<bfd_error>>).
  
  	If <<bfd_openr_iovec>> returns <<NULL>> then an error has
  	occurred.  Possible errors are <<bfd_error_no_memory>>,
  	<<bfd_error_invalid_target>> and <<bfd_error_system_call>>.
  
  */
  
  struct opncls
  {
    void *stream;
    file_ptr (*pread) (struct bfd *abfd, void *stream, void *buf,
  		     file_ptr nbytes, file_ptr offset);
    int (*close) (struct bfd *abfd, void *stream);
    int (*stat) (struct bfd *abfd, void *stream, struct stat *sb);
    file_ptr where;
  };
  
  static file_ptr
  opncls_btell (struct bfd *abfd)
  {
    struct opncls *vec = (struct opncls *) abfd->iostream;
    return vec->where;
  }
  
  static int
  opncls_bseek (struct bfd *abfd, file_ptr offset, int whence)
  {
    struct opncls *vec = (struct opncls *) abfd->iostream;
    switch (whence)
      {
      case SEEK_SET: vec->where = offset; break;
      case SEEK_CUR: vec->where += offset; break;
      case SEEK_END: return -1;
      }
    return 0;
  }
  
  static file_ptr
  opncls_bread (struct bfd *abfd, void *buf, file_ptr nbytes)
  {
    struct opncls *vec = (struct opncls *) abfd->iostream;
    file_ptr nread = (vec->pread) (abfd, vec->stream, buf, nbytes, vec->where);
    if (nread < 0)
      return nread;
    vec->where += nread;
    return nread;
  }
  
  static file_ptr
  opncls_bwrite (struct bfd *abfd ATTRIBUTE_UNUSED,
  	      const void *where ATTRIBUTE_UNUSED,
  	      file_ptr nbytes ATTRIBUTE_UNUSED)
  {
    return -1;
  }
  
  static int
  opncls_bclose (struct bfd *abfd)
  {
    struct opncls *vec = (struct opncls *) abfd->iostream;
    /* Since the VEC's memory is bound to the bfd deleting the bfd will
       free it.  */
    int status = 0;
    if (vec->close != NULL)
      status = (vec->close) (abfd, vec->stream);
    abfd->iostream = NULL;
    return status;
  }
  
  static int
  opncls_bflush (struct bfd *abfd ATTRIBUTE_UNUSED)
  {
    return 0;
  }
  
  static int
  opncls_bstat (struct bfd *abfd, struct stat *sb)
  {
    struct opncls *vec = (struct opncls *) abfd->iostream;
  
    memset (sb, 0, sizeof (*sb));
    if (vec->stat == NULL)
      return 0;
  
    return (vec->stat) (abfd, vec->stream, sb);
  }
  
  static void *
  opncls_bmmap (struct bfd *abfd ATTRIBUTE_UNUSED,
  	      void *addr ATTRIBUTE_UNUSED,
  	      bfd_size_type len ATTRIBUTE_UNUSED,
  	      int prot ATTRIBUTE_UNUSED,
  	      int flags ATTRIBUTE_UNUSED,
  	      file_ptr offset ATTRIBUTE_UNUSED,
                void **map_addr ATTRIBUTE_UNUSED,
                bfd_size_type *map_len ATTRIBUTE_UNUSED)
  {
    return (void *) -1;
  }
  
  static const struct bfd_iovec opncls_iovec = {
    &opncls_bread, &opncls_bwrite, &opncls_btell, &opncls_bseek,
    &opncls_bclose, &opncls_bflush, &opncls_bstat, &opncls_bmmap
  };
  
  bfd *
  bfd_openr_iovec (const char *filename, const char *target,
  		 void *(*open_p) (struct bfd *, void *),
  		 void *open_closure,
  		 file_ptr (*pread_p) (struct bfd *, void *, void *,
  				      file_ptr, file_ptr),
  		 int (*close_p) (struct bfd *, void *),
  		 int (*stat_p) (struct bfd *, void *, struct stat *))
  {
    bfd *nbfd;
    const bfd_target *target_vec;
    struct opncls *vec;
    void *stream;
  
    nbfd = _bfd_new_bfd ();
    if (nbfd == NULL)
      return NULL;
  
    target_vec = bfd_find_target (target, nbfd);
    if (target_vec == NULL)
      {
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
  
    nbfd->filename = filename;
    nbfd->direction = read_direction;
  
    /* `open_p (...)' would get expanded by an the open(2) syscall macro.  */
    stream = (*open_p) (nbfd, open_closure);
    if (stream == NULL)
      {
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
  
    vec = (struct opncls *) bfd_zalloc (nbfd, sizeof (struct opncls));
    vec->stream = stream;
    vec->pread = pread_p;
    vec->close = close_p;
    vec->stat = stat_p;
  
    nbfd->iovec = &opncls_iovec;
    nbfd->iostream = vec;
  
    return nbfd;
  }
  
  /* bfd_openw -- open for writing.
     Returns a pointer to a freshly-allocated BFD on success, or NULL.
  
     See comment by bfd_fdopenr before you try to modify this function.  */
  
  /*
  FUNCTION
  	bfd_openw
  
  SYNOPSIS
  	bfd *bfd_openw (const char *filename, const char *target);
  
  DESCRIPTION
  	Create a BFD, associated with file @var{filename}, using the
  	file format @var{target}, and return a pointer to it.
  
  	Possible errors are <<bfd_error_system_call>>, <<bfd_error_no_memory>>,
  	<<bfd_error_invalid_target>>.
  */
  
  bfd *
  bfd_openw (const char *filename, const char *target)
  {
    bfd *nbfd;
    const bfd_target *target_vec;
  
    /* nbfd has to point to head of malloc'ed block so that bfd_close may
       reclaim it correctly.  */
    nbfd = _bfd_new_bfd ();
    if (nbfd == NULL)
      return NULL;
  
    target_vec = bfd_find_target (target, nbfd);
    if (target_vec == NULL)
      {
        _bfd_delete_bfd (nbfd);
        return NULL;
      }
  
    nbfd->filename = filename;
    nbfd->direction = write_direction;
  
    if (bfd_open_file (nbfd) == NULL)
      {
        /* File not writeable, etc.  */
        bfd_set_error (bfd_error_system_call);
        _bfd_delete_bfd (nbfd);
        return NULL;
    }
  
    return nbfd;
  }
  
  static inline void
  _maybe_make_executable (bfd * abfd)
  {
    /* If the file was open for writing and is now executable,
       make it so.  */
    if (abfd->direction == write_direction
        && (abfd->flags & (EXEC_P | DYNAMIC)) != 0)
      {
        struct stat buf;
  
        if (stat (abfd->filename, &buf) == 0
  	  /* Do not attempt to change non-regular files.  This is
  	     here especially for configure scripts and kernel builds
  	     which run tests with "ld [...] -o /dev/null".  */
  	  && S_ISREG(buf.st_mode))
  	{
  	  unsigned int mask = umask (0);
  
  	  umask (mask);
  	  chmod (abfd->filename,
  		 (0777
  		  & (buf.st_mode | ((S_IXUSR | S_IXGRP | S_IXOTH) &~ mask))));
  	}
      }
  }
  
  /*
  
  FUNCTION
  	bfd_close
  
  SYNOPSIS
  	bfd_boolean bfd_close (bfd *abfd);
  
  DESCRIPTION
  
  	Close a BFD. If the BFD was open for writing, then pending
  	operations are completed and the file written out and closed.
  	If the created file is executable, then <<chmod>> is called
  	to mark it as such.
  
  	All memory attached to the BFD is released.
  
  	The file descriptor associated with the BFD is closed (even
  	if it was passed in to BFD by <<bfd_fdopenr>>).
  
  RETURNS
  	<<TRUE>> is returned if all is ok, otherwise <<FALSE>>.
  */
  
  
  bfd_boolean
  bfd_close (bfd *abfd)
  {
    bfd_boolean ret;
  
    if (bfd_write_p (abfd))
      {
        if (! BFD_SEND_FMT (abfd, _bfd_write_contents, (abfd)))
  	return FALSE;
      }
  
    if (! BFD_SEND (abfd, _close_and_cleanup, (abfd)))
      return FALSE;
  
    ret = abfd->iovec->bclose (abfd) == 0;
  
    if (ret)
      _maybe_make_executable (abfd);
  
    _bfd_delete_bfd (abfd);
  
    return ret;
  }
  
  /*
  FUNCTION
  	bfd_close_all_done
  
  SYNOPSIS
  	bfd_boolean bfd_close_all_done (bfd *);
  
  DESCRIPTION
  	Close a BFD.  Differs from <<bfd_close>> since it does not
  	complete any pending operations.  This routine would be used
  	if the application had just used BFD for swapping and didn't
  	want to use any of the writing code.
  
  	If the created file is executable, then <<chmod>> is called
  	to mark it as such.
  
  	All memory attached to the BFD is released.
  
  RETURNS
  	<<TRUE>> is returned if all is ok, otherwise <<FALSE>>.
  */
  
  bfd_boolean
  bfd_close_all_done (bfd *abfd)
  {
    bfd_boolean ret;
  
    ret = bfd_cache_close (abfd);
  
    if (ret)
      _maybe_make_executable (abfd);
  
    _bfd_delete_bfd (abfd);
  
    return ret;
  }
  
  /*
  FUNCTION
  	bfd_create
  
  SYNOPSIS
  	bfd *bfd_create (const char *filename, bfd *templ);
  
  DESCRIPTION
  	Create a new BFD in the manner of <<bfd_openw>>, but without
  	opening a file. The new BFD takes the target from the target
  	used by @var{templ}. The format is always set to <<bfd_object>>.
  */
  
  bfd *
  bfd_create (const char *filename, bfd *templ)
  {
    bfd *nbfd;
  
    nbfd = _bfd_new_bfd ();
    if (nbfd == NULL)
      return NULL;
    nbfd->filename = filename;
    if (templ)
      nbfd->xvec = templ->xvec;
    nbfd->direction = no_direction;
    bfd_set_format (nbfd, bfd_object);
  
    return nbfd;
  }
  
  /*
  FUNCTION
  	bfd_make_writable
  
  SYNOPSIS
  	bfd_boolean bfd_make_writable (bfd *abfd);
  
  DESCRIPTION
  	Takes a BFD as created by <<bfd_create>> and converts it
  	into one like as returned by <<bfd_openw>>.  It does this
  	by converting the BFD to BFD_IN_MEMORY.  It's assumed that
  	you will call <<bfd_make_readable>> on this bfd later.
  
  RETURNS
  	<<TRUE>> is returned if all is ok, otherwise <<FALSE>>.
  */
  
  bfd_boolean
  bfd_make_writable (bfd *abfd)
  {
    struct bfd_in_memory *bim;
  
    if (abfd->direction != no_direction)
      {
        bfd_set_error (bfd_error_invalid_operation);
        return FALSE;
      }
  
    bim = (struct bfd_in_memory *) bfd_malloc (sizeof (struct bfd_in_memory));
    if (bim == NULL)
      return FALSE;	/* bfd_error already set.  */
    abfd->iostream = bim;
    /* bfd_bwrite will grow these as needed.  */
    bim->size = 0;
    bim->buffer = 0;
  
    abfd->flags |= BFD_IN_MEMORY;
    abfd->iovec = &_bfd_memory_iovec;
    abfd->origin = 0;
    abfd->direction = write_direction;
    abfd->where = 0;
  
    return TRUE;
  }
  
  /*
  FUNCTION
  	bfd_make_readable
  
  SYNOPSIS
  	bfd_boolean bfd_make_readable (bfd *abfd);
  
  DESCRIPTION
  	Takes a BFD as created by <<bfd_create>> and
  	<<bfd_make_writable>> and converts it into one like as
  	returned by <<bfd_openr>>.  It does this by writing the
  	contents out to the memory buffer, then reversing the
  	direction.
  
  RETURNS
  	<<TRUE>> is returned if all is ok, otherwise <<FALSE>>.  */
  
  bfd_boolean
  bfd_make_readable (bfd *abfd)
  {
    if (abfd->direction != write_direction || !(abfd->flags & BFD_IN_MEMORY))
      {
        bfd_set_error (bfd_error_invalid_operation);
        return FALSE;
      }
  
    if (! BFD_SEND_FMT (abfd, _bfd_write_contents, (abfd)))
      return FALSE;
  
    if (! BFD_SEND (abfd, _close_and_cleanup, (abfd)))
      return FALSE;
  
    abfd->arch_info = &bfd_default_arch_struct;
  
    abfd->where = 0;
    abfd->format = bfd_unknown;
    abfd->my_archive = NULL;
    abfd->origin = 0;
    abfd->opened_once = FALSE;
    abfd->output_has_begun = FALSE;
    abfd->section_count = 0;
    abfd->usrdata = NULL;
    abfd->cacheable = FALSE;
    abfd->flags |= BFD_IN_MEMORY;
    abfd->mtime_set = FALSE;
  
    abfd->target_defaulted = TRUE;
    abfd->direction = read_direction;
    abfd->sections = 0;
    abfd->symcount = 0;
    abfd->outsymbols = 0;
    abfd->tdata.any = 0;
  
    bfd_section_list_clear (abfd);
    bfd_check_format (abfd, bfd_object);
  
    return TRUE;
  }
  
  /*
  FUNCTION
  	bfd_alloc
  
  SYNOPSIS
  	void *bfd_alloc (bfd *abfd, bfd_size_type wanted);
  
  DESCRIPTION
  	Allocate a block of @var{wanted} bytes of memory attached to
  	<<abfd>> and return a pointer to it.
  */
  
  void *
  bfd_alloc (bfd *abfd, bfd_size_type size)
  {
    void *ret;
  
    if (size != (unsigned long) size)
      {
        bfd_set_error (bfd_error_no_memory);
        return NULL;
      }
  
    ret = objalloc_alloc ((struct objalloc *) abfd->memory, (unsigned long) size);
    if (ret == NULL)
      bfd_set_error (bfd_error_no_memory);
    return ret;
  }
  
  /*
  INTERNAL_FUNCTION
  	bfd_alloc2
  
  SYNOPSIS
  	void *bfd_alloc2 (bfd *abfd, bfd_size_type nmemb, bfd_size_type size);
  
  DESCRIPTION
  	Allocate a block of @var{nmemb} elements of @var{size} bytes each
  	of memory attached to <<abfd>> and return a pointer to it.
  */
  
  void *
  bfd_alloc2 (bfd *abfd, bfd_size_type nmemb, bfd_size_type size)
  {
    void *ret;
  
    if ((nmemb | size) >= HALF_BFD_SIZE_TYPE
        && size != 0
        && nmemb > ~(bfd_size_type) 0 / size)
      {
        bfd_set_error (bfd_error_no_memory);
        return NULL;
      }
  
    size *= nmemb;
  
    if (size != (unsigned long) size)
      {
        bfd_set_error (bfd_error_no_memory);
        return NULL;
      }
  
    ret = objalloc_alloc ((struct objalloc *) abfd->memory, (unsigned long) size);
    if (ret == NULL)
      bfd_set_error (bfd_error_no_memory);
    return ret;
  }
  
  /*
  FUNCTION
  	bfd_zalloc
  
  SYNOPSIS
  	void *bfd_zalloc (bfd *abfd, bfd_size_type wanted);
  
  DESCRIPTION
  	Allocate a block of @var{wanted} bytes of zeroed memory
  	attached to <<abfd>> and return a pointer to it.
  */
  
  void *
  bfd_zalloc (bfd *abfd, bfd_size_type size)
  {
    void *res;
  
    res = bfd_alloc (abfd, size);
    if (res)
      memset (res, 0, (size_t) size);
    return res;
  }
  
  /*
  INTERNAL_FUNCTION
  	bfd_zalloc2
  
  SYNOPSIS
  	void *bfd_zalloc2 (bfd *abfd, bfd_size_type nmemb, bfd_size_type size);
  
  DESCRIPTION
  	Allocate a block of @var{nmemb} elements of @var{size} bytes each
  	of zeroed memory attached to <<abfd>> and return a pointer to it.
  */
  
  void *
  bfd_zalloc2 (bfd *abfd, bfd_size_type nmemb, bfd_size_type size)
  {
    void *res;
  
    if ((nmemb | size) >= HALF_BFD_SIZE_TYPE
        && size != 0
        && nmemb > ~(bfd_size_type) 0 / size)
      {
        bfd_set_error (bfd_error_no_memory);
        return NULL;
      }
  
    size *= nmemb;
  
    res = bfd_alloc (abfd, size);
    if (res)
      memset (res, 0, (size_t) size);
    return res;
  }
  
  /* Free a block allocated for a BFD.
     Note:  Also frees all more recently allocated blocks!  */
  
  void
  bfd_release (bfd *abfd, void *block)
  {
    objalloc_free_block ((struct objalloc *) abfd->memory, block);
  }
  
  
  /*
     GNU Extension: separate debug-info files
  
     The idea here is that a special section called .gnu_debuglink might be
     embedded in a binary file, which indicates that some *other* file
     contains the real debugging information. This special section contains a
     filename and CRC32 checksum, which we read and resolve to another file,
     if it exists.
  
     This facilitates "optional" provision of debugging information, without
     having to provide two complete copies of every binary object (with and
     without debug symbols).  */
  
  #define GNU_DEBUGLINK		".gnu_debuglink"
  #define GNU_DEBUGALTLINK	".gnu_debugaltlink"
  
  /*
  FUNCTION
  	bfd_calc_gnu_debuglink_crc32
  
  SYNOPSIS
  	unsigned long bfd_calc_gnu_debuglink_crc32
  	  (unsigned long crc, const unsigned char *buf, bfd_size_type len);
  
  DESCRIPTION
  	Computes a CRC value as used in the .gnu_debuglink section.
  	Advances the previously computed @var{crc} value by computing
  	and adding in the crc32 for @var{len} bytes of @var{buf}.
  
  RETURNS
  	Return the updated CRC32 value.
  */
  
  unsigned long
  bfd_calc_gnu_debuglink_crc32 (unsigned long crc,
  			      const unsigned char *buf,
  			      bfd_size_type len)
  {
    static const unsigned long crc32_table[256] =
      {
        0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
        0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
        0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
        0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
        0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
        0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
        0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
        0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
        0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
        0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
        0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
        0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
        0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
        0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
        0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
        0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
        0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
        0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
        0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
        0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
        0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
        0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
        0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
        0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
        0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
        0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
        0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
        0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
        0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
        0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
        0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
        0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
        0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
        0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
        0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
        0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
        0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
        0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
        0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
        0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
        0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
        0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
        0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
        0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
        0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
        0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
        0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
        0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
        0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
        0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
        0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
        0x2d02ef8d
      };
    const unsigned char *end;
  
    crc = ~crc & 0xffffffff;
    for (end = buf + len; buf < end; ++ buf)
      crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
    return ~crc & 0xffffffff;
  }
  
  
  /*
  FUNCTION
  	bfd_get_debug_link_info
  
  SYNOPSIS
  	char *bfd_get_debug_link_info (bfd *abfd, unsigned long *crc32_out);
  
  DESCRIPTION
  	fetch the filename and CRC32 value for any separate debuginfo
  	associated with @var{abfd}. Return NULL if no such info found,
  	otherwise return filename and update @var{crc32_out}.  The
  	returned filename is allocated with @code{malloc}; freeing it
  	is the responsibility of the caller.
  */
  
  char *
  bfd_get_debug_link_info (bfd *abfd, unsigned long *crc32_out)
  {
    asection *sect;
    unsigned long crc32;
    bfd_byte *contents;
    int crc_offset;
    char *name;
  
    BFD_ASSERT (abfd);
    BFD_ASSERT (crc32_out);
  
    sect = bfd_get_section_by_name (abfd, GNU_DEBUGLINK);
  
    if (sect == NULL)
      return NULL;
  
    if (!bfd_malloc_and_get_section (abfd, sect, &contents))
      {
        if (contents != NULL)
  	free (contents);
        return NULL;
      }
  
    /* Crc value is stored after the filename, aligned up to 4 bytes.  */
    name = (char *) contents;
    crc_offset = strlen (name) + 1;
    crc_offset = (crc_offset + 3) & ~3;
  
    crc32 = bfd_get_32 (abfd, contents + crc_offset);
  
    *crc32_out = crc32;
    return name;
  }
  
  /*
  FUNCTION
  	bfd_get_alt_debug_link_info
  
  SYNOPSIS
  	char *bfd_get_alt_debug_link_info (bfd *abfd, unsigned long *crc32_out);
  
  DESCRIPTION
  	Fetch the filename and BuildID value for any alternate debuginfo
  	associated with @var{abfd}.  Return NULL if no such info found,
  	otherwise return filename and update @var{buildid_out}.  The
  	returned filename is allocated with @code{malloc}; freeing it
  	is the responsibility of the caller.
  */
  
  char *
  bfd_get_alt_debug_link_info (bfd * abfd, unsigned long * buildid_out)
  {
    asection *sect;
    bfd_byte *contents;
    int buildid_offset;
    char *name;
  
    BFD_ASSERT (abfd);
    BFD_ASSERT (buildid_out);
  
    sect = bfd_get_section_by_name (abfd, GNU_DEBUGALTLINK);
  
    if (sect == NULL)
      return NULL;
  
    if (!bfd_malloc_and_get_section (abfd, sect, & contents))
      {
        if (contents != NULL)
  	free (contents);
        return NULL;
      }
  
    /* BuildID value is stored after the filename, aligned up to 4 bytes.  */
    name = (char *) contents;
    buildid_offset = strlen (name) + 1;
    buildid_offset = (buildid_offset + 3) & ~3;
  
    * buildid_out = bfd_get_32 (abfd, contents + buildid_offset);
  
    return name;
  }
  
  /*
  INTERNAL_FUNCTION
  	separate_debug_file_exists
  
  SYNOPSIS
  	bfd_boolean separate_debug_file_exists
  	  (char *name, unsigned long crc32);
  
  DESCRIPTION
  	Checks to see if @var{name} is a file and if its contents
  	match @var{crc32}.
  */
  
  static bfd_boolean
  separate_debug_file_exists (const char *name, const unsigned long crc)
  {
    static unsigned char buffer [8 * 1024];
    unsigned long file_crc = 0;
    FILE *f;
    bfd_size_type count;
  
    BFD_ASSERT (name);
  
    f = real_fopen (name, FOPEN_RB);
    if (f == NULL)
      return FALSE;
  
    while ((count = fread (buffer, 1, sizeof (buffer), f)) > 0)
      file_crc = bfd_calc_gnu_debuglink_crc32 (file_crc, buffer, count);
  
    fclose (f);
  
    return crc == file_crc;
  }
  
  /*
  INTERNAL_FUNCTION
  	separate_alt_debug_file_exists
  
  SYNOPSIS
  	bfd_boolean separate_alt_debug_file_exists
  	  (char *name, unsigned long crc32);
  
  DESCRIPTION
  	Checks to see if @var{name} is a file and if its BuildID
  	matches @var{buildid}.
  */
  
  static bfd_boolean
  separate_alt_debug_file_exists (const char *name,
  				const unsigned long buildid ATTRIBUTE_UNUSED)
  {
    FILE *f;
  
    BFD_ASSERT (name);
  
    f = real_fopen (name, FOPEN_RB);
    if (f == NULL)
      return FALSE;
  
    /* FIXME: Add code to check buildid.  */
  
    fclose (f);
  
    return TRUE;
  }
  
  /*
  INTERNAL_FUNCTION
  	find_separate_debug_file
  
  SYNOPSIS
  	char *find_separate_debug_file (bfd *abfd);
  
  DESCRIPTION
  	Searches @var{abfd} for a section called @var{section_name} which
  	is expected to contain a reference to a file containing separate
  	debugging information.  The function scans various locations in
  	the filesystem, including the file tree rooted at
  	@var{debug_file_directory}, and returns the first matching
  	filename that it finds.  If @var{check_crc} is TRUE then the
  	contents of the file must also match the CRC value contained in
  	@var{section_name}.  Returns NULL if no valid file could be found.
  */
  
  typedef char *      (* get_func_type) (bfd *, unsigned long *);
  typedef bfd_boolean (* check_func_type) (const char *, const unsigned long);
  
  static char *
  find_separate_debug_file (bfd *           abfd,
  			  const char *    debug_file_directory,
  			  get_func_type   get_func,
  			  check_func_type check_func)
  {
    char *base;
    char *dir;
    char *debugfile;
    char *canon_dir;
    unsigned long crc32;
    size_t dirlen;
    size_t canon_dirlen;
  
    BFD_ASSERT (abfd);
    if (debug_file_directory == NULL)
      debug_file_directory = ".";
  
    /* BFD may have been opened from a stream.  */
    if (abfd->filename == NULL)
      {
        bfd_set_error (bfd_error_invalid_operation);
        return NULL;
      }
  
    base = get_func (abfd, & crc32);
      
    if (base == NULL)
      return NULL;
  
    if (base[0] == '\0')
      {
        free (base);
        bfd_set_error (bfd_error_no_debug_section);
        return NULL;
      }
  
    for (dirlen = strlen (abfd->filename); dirlen > 0; dirlen--)
      if (IS_DIR_SEPARATOR (abfd->filename[dirlen - 1]))
        break;
  
    dir = (char *) bfd_malloc (dirlen + 1);
    if (dir == NULL)
      {
        free (base);
        return NULL;
      }
    memcpy (dir, abfd->filename, dirlen);
    dir[dirlen] = '\0';
  
    /* Compute the canonical name of the bfd object with all symbolic links
       resolved, for use in the global debugfile directory.  */
    canon_dir = lrealpath (abfd->filename);
    for (canon_dirlen = strlen (canon_dir); canon_dirlen > 0; canon_dirlen--)
      if (IS_DIR_SEPARATOR (canon_dir[canon_dirlen - 1]))
        break;
    canon_dir[canon_dirlen] = '\0';
  
    debugfile = (char *)
        bfd_malloc (strlen (debug_file_directory) + 1
                    + (canon_dirlen > dirlen ? canon_dirlen : dirlen)
                    + strlen (".debug/")
                    + strlen (base)
                    + 1);
    if (debugfile == NULL)
      goto found; /* Actually this returns NULL.  */
  
    /* First try in the same directory as the original file:  */
    strcpy (debugfile, dir);
    strcat (debugfile, base);
  
    if (check_func (debugfile, crc32))
      goto found;
  
    /* Then try in a subdirectory called .debug.  */
    strcpy (debugfile, dir);
    strcat (debugfile, ".debug/");
    strcat (debugfile, base);
  
    if (check_func (debugfile, crc32))
      goto found;
  
    /* Then try in the global debugfile directory.  */
    strcpy (debugfile, debug_file_directory);
    dirlen = strlen (debug_file_directory) - 1;
    if (dirlen > 0
        && debug_file_directory[dirlen] != '/'
        && canon_dir[0] != '/')
      strcat (debugfile, "/");
    strcat (debugfile, canon_dir);
    strcat (debugfile, base);
  
    if (check_func (debugfile, crc32))
      goto found;
  
    /* Failed to find the file.  */
    free (debugfile);
    debugfile = NULL;
  
   found:
    free (base);
    free (dir);
    free (canon_dir);
    return debugfile;
  }
  
  
  /*
  FUNCTION
  	bfd_follow_gnu_debuglink
  
  SYNOPSIS
  	char *bfd_follow_gnu_debuglink (bfd *abfd, const char *dir);
  
  DESCRIPTION
  
  	Takes a BFD and searches it for a .gnu_debuglink section.  If this
  	section is found, it examines the section for the name and checksum
  	of a '.debug' file containing auxiliary debugging information.  It
  	then searches the filesystem for this .debug file in some standard
  	locations, including the directory tree rooted at @var{dir}, and if
  	found returns the full filename.
  
  	If @var{dir} is NULL, it will search a default path configured into
  	libbfd at build time.  [XXX this feature is not currently
  	implemented].
  
  RETURNS
  	<<NULL>> on any errors or failure to locate the .debug file,
  	otherwise a pointer to a heap-allocated string containing the
  	filename.  The caller is responsible for freeing this string.
  */
  
  char *
  bfd_follow_gnu_debuglink (bfd *abfd, const char *dir)
  {
    return find_separate_debug_file (abfd, dir,
  				   bfd_get_debug_link_info,
  				   separate_debug_file_exists);
  }
  
  /*
  FUNCTION
  	bfd_follow_gnu_debugaltlink
  
  SYNOPSIS
  	char *bfd_follow_gnu_debugaltlink (bfd *abfd, const char *dir);
  
  DESCRIPTION
  
  	Takes a BFD and searches it for a .gnu_debugaltlink section.  If this
  	section is found, it examines the section for the name of a file
  	containing auxiliary debugging information.  It	then searches the
  	filesystem for this file in a set of standard locations, including
  	the directory tree rooted at @var{dir}, and if found returns the
  	full filename.
  
  	If @var{dir} is NULL, it will search a default path configured into
  	libbfd at build time.  [FIXME: This feature is not currently
  	implemented].
  
  RETURNS
  	<<NULL>> on any errors or failure to locate the debug file,
  	otherwise a pointer to a heap-allocated string containing the
  	filename.  The caller is responsible for freeing this string.
  */
  
  char *
  bfd_follow_gnu_debugaltlink (bfd *abfd, const char *dir)
  {
    return find_separate_debug_file (abfd, dir,
  				   bfd_get_alt_debug_link_info,
  				   separate_alt_debug_file_exists);
  }
  
  /*
  FUNCTION
  	bfd_create_gnu_debuglink_section
  
  SYNOPSIS
  	struct bfd_section *bfd_create_gnu_debuglink_section
  	  (bfd *abfd, const char *filename);
  
  DESCRIPTION
  
  	Takes a @var{BFD} and adds a .gnu_debuglink section to it.  The section is sized
  	to be big enough to contain a link to the specified @var{filename}.
  
  RETURNS
  	A pointer to the new section is returned if all is ok.  Otherwise <<NULL>> is
  	returned and bfd_error is set.
  */
  
  asection *
  bfd_create_gnu_debuglink_section (bfd *abfd, const char *filename)
  {
    asection *sect;
    bfd_size_type debuglink_size;
    flagword flags;
  
    if (abfd == NULL || filename == NULL)
      {
        bfd_set_error (bfd_error_invalid_operation);
        return NULL;
      }
  
    /* Strip off any path components in filename.  */
    filename = lbasename (filename);
  
    sect = bfd_get_section_by_name (abfd, GNU_DEBUGLINK);
    if (sect)
      {
        /* Section already exists.  */
        bfd_set_error (bfd_error_invalid_operation);
        return NULL;
      }
  
    flags = SEC_HAS_CONTENTS | SEC_READONLY | SEC_DEBUGGING;
    sect = bfd_make_section_with_flags (abfd, GNU_DEBUGLINK, flags);
    if (sect == NULL)
      return NULL;
  
    debuglink_size = strlen (filename) + 1;
    debuglink_size += 3;
    debuglink_size &= ~3;
    debuglink_size += 4;
  
    if (! bfd_set_section_size (abfd, sect, debuglink_size))
      /* XXX Should we delete the section from the bfd ?  */
      return NULL;
  
    return sect;
  }
  
  
  /*
  FUNCTION
  	bfd_fill_in_gnu_debuglink_section
  
  SYNOPSIS
  	bfd_boolean bfd_fill_in_gnu_debuglink_section
  	  (bfd *abfd, struct bfd_section *sect, const char *filename);
  
  DESCRIPTION
  
  	Takes a @var{BFD} and containing a .gnu_debuglink section @var{SECT}
  	and fills in the contents of the section to contain a link to the
  	specified @var{filename}.  The filename should be relative to the
  	current directory.
  
  RETURNS
  	<<TRUE>> is returned if all is ok.  Otherwise <<FALSE>> is returned
  	and bfd_error is set.
  */
  
  bfd_boolean
  bfd_fill_in_gnu_debuglink_section (bfd *abfd,
  				   struct bfd_section *sect,
  				   const char *filename)
  {
    bfd_size_type debuglink_size;
    unsigned long crc32;
    char * contents;
    bfd_size_type crc_offset;
    FILE * handle;
    static unsigned char buffer[8 * 1024];
    size_t count;
    size_t filelen;
  
    if (abfd == NULL || sect == NULL || filename == NULL)
      {
        bfd_set_error (bfd_error_invalid_operation);
        return FALSE;
      }
  
    /* Make sure that we can read the file.
       XXX - Should we attempt to locate the debug info file using the same
       algorithm as gdb ?  At the moment, since we are creating the
       .gnu_debuglink section, we insist upon the user providing us with a
       correct-for-section-creation-time path, but this need not conform to
       the gdb location algorithm.  */
    handle = real_fopen (filename, FOPEN_RB);
    if (handle == NULL)
      {
        bfd_set_error (bfd_error_system_call);
        return FALSE;
      }
  
    crc32 = 0;
    while ((count = fread (buffer, 1, sizeof buffer, handle)) > 0)
      crc32 = bfd_calc_gnu_debuglink_crc32 (crc32, buffer, count);
    fclose (handle);
  
    /* Strip off any path components in filename,
       now that we no longer need them.  */
    filename = lbasename (filename);
  
    filelen = strlen (filename);
    debuglink_size = filelen + 1;
    debuglink_size += 3;
    debuglink_size &= ~3;
    debuglink_size += 4;
  
    contents = (char *) bfd_malloc (debuglink_size);
    if (contents == NULL)
      {
        /* XXX Should we delete the section from the bfd ?  */
        return FALSE;
      }
  
    crc_offset = debuglink_size - 4;
    memcpy (contents, filename, filelen);
    memset (contents + filelen, 0, crc_offset - filelen);
  
    bfd_put_32 (abfd, crc32, contents + crc_offset);
  
    if (! bfd_set_section_contents (abfd, sect, contents, 0, debuglink_size))
      {
        /* XXX Should we delete the section from the bfd ?  */
        free (contents);
        return FALSE;
      }
  
    return TRUE;
  }
  