Add patches to use the unexec function from xemacs. This eliminates

the need for a hack in ld.so to make emacs work.  I have submitted
these changes to a GNU emacs maintainer.

2 files changed, 706 insertions, 2 deletions

diff --git a/editors/emacs22/files/patch-ac b/editors/emacs22/files/patch-ac
index 0c0a713b1c55..525f8de259f3 100644
--- a/editors/emacs22/files/patch-ac
+++ b/editors/emacs22/files/patch-ac
@@ -1,5 +1,5 @@
---- src/s/freebsd.h.orig	Mon Jun 10 04:14:32 1996
-+++ src/s/freebsd.h	Mon May 26 21:21:55 1997
+--- src/s/freebsd.h.orig	Sun Jun  9 13:14:32 1996
++++ src/s/freebsd.h	Wed Dec  3 17:36:40 1997
 @@ -33,9 +33,16 @@
  
  #define LIBS_DEBUG
@@ -18,6 +18,15 @@
  #define SYSV_SYSTEM_DIR
  
  /* freebsd has POSIX-style pgrp behavior. */
+@@ -46,7 +53,7 @@
+ #define LD_SWITCH_SYSTEM -e start -dc -dp
+ #define HAVE_TEXT_START		/* No need to define `start_of_text'. */
+ #define START_FILES pre-crt0.o /usr/lib/crt0.o
+-#define UNEXEC unexsunos4.o
++#define UNEXEC unexfreebsd.o
+ #define RUN_TIME_REMAP
+ 
+ #ifndef N_TRELOFF
 @@ -80,6 +87,8 @@
  #define BSD 199103
  #elif __FreeBSD__ == 2
diff --git a/editors/emacs22/files/patch-ad b/editors/emacs22/files/patch-ad
new file mode 100644
index 000000000000..f2013a374044
--- /dev/null
+++ b/editors/emacs22/files/patch-ad
@@ -0,0 +1,695 @@
+--- src/unexfreebsd.c.orig	Wed Dec  3 17:28:14 1997
++++ src/unexfreebsd.c	Wed Dec  3 17:34:02 1997
+@@ -0,0 +1,692 @@
++/* Code to do an unexec for FreeBSD for a temacs linked -Bdynamic.
++   Derived from unexnetbsd.c, which was derived from unexsunos4.c
++   Copyright (C) 1992, 1993 Free Software Foundation, Inc.
++
++This file is part of XEmacs.
++
++XEmacs 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.
++
++XEmacs 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 XEmacs; see the file COPYING.  If not, write to
++the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
++Boston, MA 02111-1307, USA.  */
++
++/* Synched up with: Not in FSF? */
++
++/*
++Created 29-Oct-92 by Harlan Sexton
++Tweaked 06-Aug-93 by Dean Michaels to work with sun3.
++Converted 01-Dec-93 by Paul Mackerras to work with NetBSD shared libraries.
++Tweaked 26-Feb-94 by Shawn Carey for use with FreeBSD-1.1 shared libraries.
++*/
++
++/********************** Included .h Files **************************/
++
++#include <config.h>
++
++#include <stdarg.h>
++#include <sys/param.h>
++#include <sys/mman.h>
++#include <sys/file.h>
++#include <sys/stat.h>
++#include <sys/types.h>
++#include <string.h>
++#include <stdio.h>
++#include <a.out.h>
++#include <unistd.h>
++#include <ctype.h>
++#include <stab.h>
++#include <dirent.h>
++#include <link.h>
++
++/********************** Macros *************************************/
++
++#define SYS_ERR		strerror(errno)
++
++#define MASK_UP(x,p_of_two) \
++ ((((unsigned long) (x)) + ((p_of_two) - 1)) & (~((p_of_two) - 1)))
++
++#define MASK_DOWN(x,p_of_two) (((unsigned long) (x)) & (~((p_of_two) - 1)))
++
++/********************** Typedefs and Structs ***********************/
++
++struct translation_struct
++{
++  long txtaddr;
++  long txtoff;
++  long dataddr;
++  long datoff;
++  long bssaddr;
++  long endaddr;
++};
++
++/********************** Function Prototypes/Declarations ***********/
++
++static void unexec_error (const char *m, int use_errno, ...);
++static int unexec_open (char *filename, int flag, int mode);
++static caddr_t unexec_mmap (int fd, size_t len, int prot, int flags);
++static long unexec_seek (int fd, long position);
++static void unexec_read (int fd, long position, char *buf, int bytes);
++static void unexec_write (int fd, long position, char *buf, int bytes);
++static void unexec_pad (int fd, int bytes);
++static void unexec_fstat (int fd, struct stat *statptr);
++static void unexec_fchmod (int fd, int mode);
++static long unexec_addr_to_offset (long addr, struct translation_struct *ts);
++static void copy_relocation_site (struct relocation_info *ri, 
++                                  caddr_t from_base_addr, 
++                                  caddr_t to_base_addr, 
++                                  struct translation_struct *ts);
++static void reset_symtab (struct nlist *start, struct nlist *end, 
++                          char *strtab, long edata_value, long end_value,
++                          int shlib_image);
++static void reset_ldso_symtab (struct nzlist *start, struct nzlist *end, 
++                          char *strtab, long edata_value, long end_value,
++                          int shlib_image);
++int run_time_remap (char *dummy);
++
++/********************** Variables **********************************/
++
++/* for reporting error messages from system calls */
++extern int errno;
++extern int _DYNAMIC;
++extern char **environ;             
++
++static unsigned long sbrk_of_0_at_unexec;
++             
++/*******************************************************************/
++
++static void
++unexec_error (const char *fmt, int use_errno, ...)
++{
++  const char *err_msg = SYS_ERR;
++  va_list args;
++
++  fprintf (stderr, "unexec - ");
++  va_start (args, use_errno);
++  vfprintf (stderr, fmt, args);
++  va_end (args);
++
++  if (use_errno)
++    fprintf (stderr, ": %s", err_msg);
++  fprintf (stderr, "\n");
++  exit (1);
++  return;
++}
++
++static int
++unexec_open (char *filename, int flag, int mode)
++{
++  int fd;
++
++  errno = 0;
++
++  fd = open (filename, flag, mode);
++
++  if (fd < 0)
++    unexec_error ("Failure opening file %s", 1, filename);
++  return fd;
++}
++
++static caddr_t
++unexec_mmap (int fd, size_t len, int prot, int flags)
++{
++  caddr_t return_val;
++
++  unexec_seek (fd, 0);
++  errno = 0;
++  return_val = mmap (0, len, prot, flags, fd, 0);
++
++  if (return_val == (caddr_t) -1)
++    unexec_error ("Failure mmap'ing file", 1);
++  return return_val;
++}
++
++
++static long
++unexec_seek (int fd, long position)
++{
++  long seek_value;
++
++  if (fd <= 0)
++    unexec_error ("No file open in which to seek", 0);
++
++  errno = 0;
++
++  if (position < 0)
++    seek_value = (long) lseek (fd, 0, L_INCR);
++  else
++    seek_value = (long) lseek (fd, position, L_SET);
++
++  if (seek_value < 0)
++    unexec_error ("Failed to do a seek to 0x%x in %s", 1,
++                  position, "unexec() output file");
++
++  return seek_value;
++}
++
++static void
++unexec_read (int fd, long position, char *buf, int bytes)
++{
++  int n_read;
++  int remains = bytes;
++  position = unexec_seek (fd, position);
++
++  if (bytes < 0)
++    unexec_error ("Attempted read of %d bytes", 0, bytes);
++
++  errno = 0;
++
++  while (remains > 0)
++    {
++      n_read = read (fd, buf, remains);
++      if (n_read <= 0)
++        unexec_error ("Read failed for 0x%x bytes at offset 0x%x in %s",
++                      1, bytes, position, "unexec() output file");
++      buf += n_read;
++      remains -= n_read;
++    }
++
++  return;
++}
++
++static void
++unexec_write (int fd, long position, char *buf, int bytes)
++{
++  int n_written;
++  int remains = bytes;
++  position = unexec_seek (fd, position);
++
++  if (bytes < 0)
++    unexec_error ("Attempted write of %d bytes in %s",
++                  0, bytes, "unexec() output file");
++
++  errno = 0;
++
++  while (remains > 0)
++    {
++      n_written = write (fd, buf, remains);
++      if (n_written <= 0)
++        unexec_error ("Write failed for 0x%x bytes at offset 0x%x in %s",
++                      1, bytes, position, "unexec() output file");
++      buf += n_written;
++      remains -= n_written;
++    }
++
++  return;
++}
++
++static void 
++unexec_pad (int fd, int bytes)
++{
++  if (bytes > 0)
++    {
++      char buf[1024];
++      int remaining = bytes;
++
++      memset (buf, 0, sizeof (buf));
++
++      while (remaining > 0)
++        {
++          int this_write = (remaining > sizeof(buf))?sizeof(buf):remaining;
++          unexec_write (fd, -1, buf, this_write);
++          remaining -= this_write;
++        }
++    }
++}
++
++static void
++unexec_fstat (int fd, struct stat *statptr)
++{
++  errno = 0;
++  if (-1 == fstat (fd, statptr))
++    unexec_error ("fstat() failed for descriptor %d", 1, fd);
++  return;
++}
++
++static void
++unexec_fchmod (int fd, int mode)
++{
++  errno = 0;
++  if (-1 == fchmod (fd, mode))
++    unexec_error ("fchmod() failed for descriptor %d", 1, fd);
++  return;
++}
++
++static long
++unexec_addr_to_offset (long addr, struct translation_struct *ts)
++                             
++{
++  if ((addr < ts->txtaddr) || (addr >= ts->bssaddr))
++    return -1;
++  else if (addr >= ts->dataddr)
++    return ((long) ((addr - ts->dataddr) + ts->datoff));
++  else 
++    return ((long) ((addr - ts->txtaddr) + ts->txtoff));
++}
++
++
++/*
++ * "LD.SO" DATA AND SYMBOL TABLE OPERATIONS 
++ */
++
++static void
++copy_relocation_site (struct relocation_info *ri, 
++                      caddr_t from_base_addr,
++                      caddr_t to_base_addr,
++                      struct translation_struct *ts)
++{
++  long offset;
++  caddr_t from, to;
++
++  /* We can get relocation sites in the bss region, for objects whose
++     contents are copied from a shared library.  We don't need or want
++     to restore these at present. */
++#ifndef sparc
++  if (ri->r_copy)
++    return;
++#else
++  /* Struct relocation_info_sparc doesn't have member r_copy.
++     Instead, we use the address to check if this is run-time-copied. */
++  if (ri->r_address >= ts->bssaddr && ri->r_address < ts->endaddr)
++    return;
++#endif
++
++  offset = unexec_addr_to_offset (ri->r_address, ts);
++  if (offset == -1)
++    unexec_error ("bad relocation address 0x%x (0x%x)", 0, ri->r_address,
++		  ((long *)ri)[1]);
++
++  from = from_base_addr + offset;
++  to = to_base_addr + offset;
++  /* This stuff should be in a md_ file somewhere... */
++#ifndef sparc
++  switch (ri->r_length)
++    {
++    case 0:
++      *((char *) to) = *((char *) from);
++      break;
++    case 1:
++      *((short *) to) = *((short *) from);
++      break;
++    case 2:
++      *((long *) to) = *((long *) from);
++      break;
++    default:
++      unexec_error ("unknown reloc length %d seen during unexec()",
++		    0, ri->r_length);
++      break;
++    }
++#else /* sparc */
++  switch (ri->r_type)
++    {
++    case RELOC_8:
++    case RELOC_DISP8:
++      *((char *) to) = *((char *) from);
++      break;
++    case RELOC_16:
++    case RELOC_DISP16:
++      *((short *) to) = *((short *) from);
++      break;     
++    case RELOC_LO10:
++    case RELOC_13:     
++    case RELOC_22:     
++    case RELOC_HI22:
++    case RELOC_WDISP22:
++    case RELOC_WDISP30:
++    case RELOC_32:
++    case RELOC_DISP32:
++    case RELOC_GLOB_DAT:
++      *((long *) to) = *((long *) from);
++      break;
++    case RELOC_JMP_SLOT:
++      {
++        long *target = (long *) to;
++        long *source = (long *) from;
++        *target = *source;
++        target++;
++        source++;
++        *target = *source;
++        target++;
++        source++;
++        *target = *source;
++      }
++      break;
++    default:
++      unexec_error ("unknown reloc type %d seen during unexec()",
++		    0, ri->r_type);
++      break;
++    }
++#endif /* sparc */
++}
++
++static void
++reset_symtab (struct nlist *start, struct nlist *end, char *strtab,
++              long edata_value, long end_value, int shlib_image)
++{
++  struct nlist *tmp = start;
++  int found_edata = 0;
++  int found_end = 0;
++     
++  while (tmp < end)
++    {
++      int type = tmp->n_type;
++
++      if ((type == (N_UNDF | N_EXT)) &&
++          (tmp->n_value != 0))
++        unexec_error ("unexec'ing image has COMMON symbols in it -- we quit!",
++		      0);
++     
++      if (!(type & N_STAB))
++        {
++          if (!found_edata &&
++              (type == (N_EXT | N_DATA)) &&
++              tmp->n_un.n_strx &&
++              !strcmp ("_edata", strtab + tmp->n_un.n_strx))
++            {
++              tmp->n_value = edata_value;
++              found_edata = 1;
++            }
++
++
++          if ((type & N_TYPE) == N_BSS)
++            {
++              if (!found_end &&
++                  (type == (N_EXT | N_BSS)) &&
++                  tmp->n_un.n_strx &&
++                  !strcmp ("_end", strtab + tmp->n_un.n_strx))
++                {
++                  tmp->n_value = end_value;
++                  found_end = 1;
++                }
++              else if (type & N_EXT)
++                tmp->n_type = N_DATA | N_EXT;
++              else
++                tmp->n_type = N_DATA;
++            }
++
++          /* the way things are being handled here, having sbrk() in the
++             image is fatal for an image linked with shared lib's (although 
++             the code could be modified to support it), but this should 
++             never happen anyway */
++          if (shlib_image &&
++              (type == (N_EXT | N_TEXT)) &&
++              tmp->n_un.n_strx &&
++              !strcmp ("_sbrk", strtab + tmp->n_un.n_strx))
++            unexec_error ("unexec'd shlib image has sbrk() in it -- we quit!",
++                          0);
++        }
++
++      tmp++;
++    }
++} 
++     
++static void
++reset_ldso_symtab (struct nzlist *start, struct nzlist *end, char *strtab,
++              long edata_value, long end_value, int shlib_image)
++{
++  struct nzlist *tmp = start;
++  int found_edata = 0;
++  int found_end = 0;
++     
++  while (tmp < end) {
++    int type = tmp->nz_type;
++/*
++ * the following code breaks under FreeBSD-1.1-BETA, but everything
++ * seems to work perfectly if it's commented out.  This did not break
++ * anything until the changes to ld.so were made.
++ */
++/*
++    if ((type == (N_UNDF | N_EXT)) && (tmp->nz_value != 0))
++      unexec_error("unexec'ing image has COMMON symbols in rel -- we quit!",0);
++*/
++    if (!(type & N_STAB)) {
++      if (!found_edata &&
++	  (type == (N_EXT | N_DATA)) &&
++	  !strcmp ("_edata", strtab + tmp->nz_strx)) {
++	tmp->nz_value = edata_value;
++	found_edata = 1;
++      }
++
++      if ((type & N_TYPE) == N_BSS) {
++	if (!found_end &&
++	    (type == (N_EXT | N_BSS)) &&
++	    !strcmp ("_end", strtab + tmp->nz_strx)) {
++	  tmp->nz_value = end_value;
++	  found_end = 1;
++	} else if (type & N_EXT)
++	  tmp->nz_type = N_DATA | N_EXT;
++	else
++	  tmp->nz_type = N_DATA;
++      }
++
++      /* the way things are being handled here, having sbrk() in the
++	 image is fatal for an image linked with shared lib's (although 
++	 the code could be modified to support it), but this should 
++	 never happen anyway */
++      if (shlib_image &&
++	  (type == (N_EXT | N_TEXT)) &&
++	  !strcmp ("_sbrk", strtab + tmp->nz_strx))
++	unexec_error("unexec'd shlib image has sbrk() ref -- we quit!", 0);
++    }
++    tmp++;
++  }
++} 
++     
++extern int getpagesize (void);
++
++/*
++ * EXPORTED FUNCTIONS 
++ */
++
++/* this has to be a global variable to prevent the optimizers from
++ * assuming that it can not be 0.  
++*/
++static void *dynamic_addr = (void *) &_DYNAMIC;
++
++int
++unexec (char *new_name, char *old_name,
++        unsigned int emacs_edata, unsigned int dummy1, unsigned int dummy2)
++{
++  /* ld.so data */
++  struct _dynamic *ld = 0;
++  struct section_dispatch_table *ld2 = 0;
++  /* old and new state */
++  int old_fd;
++  int new_fd;
++  caddr_t old_base_addr;
++  caddr_t new_base_addr;
++  struct exec old_hdr;
++  struct exec new_hdr;
++  struct stat old_buf;
++  struct stat new_buf;
++  /* some process specific "constants" */
++  unsigned long n_pagsiz, new_edata;
++  long page_size = getpagesize ();
++  caddr_t plt_end;
++  caddr_t current_break = (caddr_t) sbrk (0);
++
++  if (!page_size)
++    unexec_error ("unexec() failed because we can't get the size of a page!",
++                  0);
++
++  /* see if this is a -Bdynamic image -- if so, find ld.so structures */
++  if (dynamic_addr)
++    {
++      ld = (struct _dynamic *) dynamic_addr;
++      ld2 = ld->d_un.d_sdt;
++      if (ld->d_version < LD_VERSION_BSD)
++        unexec_error ("%s linked with obsolete version of ld -- we quit!",
++                      0, old_name);
++    }
++
++  /* open the old and new files, figuring out how big the old one is
++     so that we can map it in */
++  old_fd = unexec_open (old_name, O_RDONLY, 0);
++  new_fd = unexec_open (new_name, O_RDWR | O_CREAT | O_TRUNC, 0666);
++
++  /* setup the header and the statbuf for old_fd */
++  unexec_read (old_fd, 0, (char *) &old_hdr, sizeof (old_hdr));
++  unexec_fstat (old_fd, &old_buf);
++
++
++  /* set up some important constants */
++  n_pagsiz = __LDPGSZ;
++  if (dynamic_addr)
++    plt_end = (caddr_t) MASK_UP (ld2->sdt_plt + ld2->sdt_plt_sz, sizeof (double));
++  else
++    plt_end = (caddr_t) N_DATADDR (old_hdr);
++
++#if 0
++  /* never write protect the variable "environ", defined in /lib/crt0.o, and
++     set in process.c and callproc.c */
++  mprotect_bottom_addr = ((unsigned long) &environ) + sizeof (char **);
++  /* never protect ABOVE the end of data emacs_edata specified */
++  mprotect_top_addr = MIN (emacs_edata, N_DATADDR (old_hdr) + old_hdr.a_data);
++#endif
++
++  /* Set up the image of the old file */
++  old_base_addr = unexec_mmap (old_fd, old_buf.st_size, PROT_READ,
++			       MAP_FILE | MAP_PRIVATE);
++  close (old_fd);
++
++  /* set up the new exec */
++  new_hdr = old_hdr;
++  new_edata = (unsigned long) MASK_UP (current_break, n_pagsiz);
++  new_hdr.a_data = new_edata - ((unsigned long) N_DATADDR (old_hdr));
++  new_hdr.a_bss  = 0;
++
++  /* set up this variable, in case we want to reset "the break" 
++     when restarting */
++  sbrk_of_0_at_unexec = ((unsigned long) MASK_UP (current_break, n_pagsiz));
++     
++  /* Write out the first approximation to the new file. The sizes of
++     each section will be correct, but there will be a number of 
++     corrections that will need to be made. */
++  {
++    long old_datoff = N_DATOFF (old_hdr);
++    long old_dataddr = N_DATADDR (old_hdr);
++    long new_treloff = N_RELOFF (new_hdr);
++    long old_treloff = N_RELOFF (old_hdr);
++    long ld_so_size = ((unsigned long) plt_end) - old_dataddr;
++    long real_data_size = current_break - plt_end;
++    long pad_size = 
++      MASK_UP (current_break, n_pagsiz) - ((unsigned long) current_break);
++
++
++    /* First, write the text segment with new header -- copy everything until
++       the start of the data segment from the old file, and then go back and 
++       write the new header. */
++    unexec_write (new_fd, 0, old_base_addr, old_datoff + ld_so_size);
++    unexec_write (new_fd, 0, (char *) &new_hdr, sizeof (new_hdr));
++
++    /* Copy the rest of the data segment from the running image. */
++    unexec_write (new_fd, old_datoff + ld_so_size, 
++                  plt_end, real_data_size);
++
++    /* pad out the data segment */
++    unexec_pad (new_fd, pad_size);
++    
++    /* Finally, copy the symbol table information from the old file. */
++    unexec_write (new_fd, new_treloff,
++                  old_base_addr + old_treloff,
++                  old_buf.st_size - old_treloff);
++  }
++     
++     
++  /* Next, map in the output file so that we can jump around fixing it
++     up. We retain the old file so that we can refer to it. */
++  unexec_fstat (new_fd, &new_buf);
++  new_base_addr = unexec_mmap (new_fd, 
++                               MASK_UP (new_buf.st_size, page_size),
++                               PROT_READ | PROT_WRITE,
++			       MAP_FILE | MAP_SHARED);
++
++
++
++  /* We need to do 2 things. First, make sure that _edata and _end (and
++     hence, curbrk) are set to the correct values. At the same time, for
++     neatness and to help with debugging, mark all the types of all ld.so
++     and nm BSS symbols in the new file to be DATA, and make sure that
++     there are no COMMON symbols in the output file, as any references to
++     these can lose really big. Second, reset all of the ld.so "relocation
++     sites" in the new file to have the values that appear in the old file
++     -- the failure to do this was the biggest loser in the old version of
++     this code. */
++
++  /* STEP 1 */
++  /* Reset the regular symbol table first. */
++  reset_symtab ((struct nlist *) (new_base_addr + N_SYMOFF(new_hdr)),
++		(struct nlist *) (new_base_addr + N_SYMOFF(new_hdr) +
++				  new_hdr.a_syms),
++		(char *) (new_base_addr + N_STROFF(new_hdr)),
++		new_edata, new_edata,
++		!!dynamic_addr);
++
++  /* Now reset the ld.so symbol table. */
++  if (dynamic_addr)
++    {
++      struct translation_struct ts;
++      struct relocation_info *tmp, *end;
++      caddr_t syms, strings;
++
++      /* set up the structure that we use to translate addresses in the
++	 old file into file offsets */
++      ts.txtaddr = N_TXTADDR (old_hdr);
++      ts.txtoff = N_TXTOFF (old_hdr);
++      ts.dataddr = N_DATADDR (old_hdr);
++      ts.datoff = N_DATOFF (old_hdr);
++      ts.bssaddr = N_DATADDR (old_hdr) + old_hdr.a_data;
++      ts.endaddr = ts.bssaddr + old_hdr.a_bss;
++
++      syms = new_base_addr + unexec_addr_to_offset(ld2->sdt_nzlist, &ts);
++      strings = new_base_addr + unexec_addr_to_offset(ld2->sdt_strings, &ts);
++      reset_ldso_symtab ((struct nzlist *) syms, (struct nzlist *) strings,
++			 (char *) strings,
++			 new_edata, new_edata,
++			 !!dynamic_addr);
++
++      /* STEP 2 */
++      tmp = (struct relocation_info *)
++	(old_base_addr + unexec_addr_to_offset(ld2->sdt_rel, &ts));
++      end = (struct relocation_info *)
++	(old_base_addr + unexec_addr_to_offset(ld2->sdt_hash, &ts));
++      while (tmp < end)
++	{
++	  copy_relocation_site (tmp, old_base_addr, new_base_addr, &ts);
++	  tmp++;
++	}
++    }
++     
++  /* get rid of the mmap-ed file space and make the output file 
++     executable -- then quit */
++  munmap (new_base_addr, MASK_UP (new_buf.st_size, page_size));
++  munmap (old_base_addr, MASK_UP (old_buf.st_size, page_size));
++  unexec_fchmod (new_fd, 0755);
++  close (new_fd);
++  return 0;
++}
++
++
++int
++run_time_remap (char *dummy)
++{
++  unsigned long current_sbrk = (unsigned long) sbrk (0);
++
++  if (sbrk_of_0_at_unexec > current_sbrk)
++    {
++      errno = 0;
++      if (brk ((caddr_t) sbrk_of_0_at_unexec))
++	fprintf (stderr, "failed to change brk addr to 0x%lx: %s\n", 
++		 sbrk_of_0_at_unexec, SYS_ERR);
++    }
++             
++  return 0;
++}