Initial revision

1 files changed, 978 insertions, 0 deletions

diff --git a/src/unexec.c b/src/unexec.c
new file mode 100644
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--- /dev/null
+++ b/src/unexec.c
@@ -0,0 +1,978 @@
+/* Copyright (C) 1985, 1986, 1987, 1988 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs 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 1, or (at your option)
+any later version.
+
+GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+
+/*
+ * unexec.c - Convert a running program into an a.out file.
+ *
+ * Author:	Spencer W. Thomas
+ * 		Computer Science Dept.
+ * 		University of Utah
+ * Date:	Tue Mar  2 1982
+ * Modified heavily since then.
+ *
+ * Synopsis:
+ *	unexec (new_name, a_name, data_start, bss_start, entry_address)
+ *	char *new_name, *a_name;
+ *	unsigned data_start, bss_start, entry_address;
+ *
+ * Takes a snapshot of the program and makes an a.out format file in the
+ * file named by the string argument new_name.
+ * If a_name is non-NULL, the symbol table will be taken from the given file.
+ * On some machines, an existing a_name file is required.
+ *
+ * The boundaries within the a.out file may be adjusted with the data_start
+ * and bss_start arguments.  Either or both may be given as 0 for defaults.
+ *
+ * Data_start gives the boundary between the text segment and the data
+ * segment of the program.  The text segment can contain shared, read-only
+ * program code and literal data, while the data segment is always unshared
+ * and unprotected.  Data_start gives the lowest unprotected address.
+ * The value you specify may be rounded down to a suitable boundary
+ * as required by the machine you are using.
+ *
+ * Specifying zero for data_start means the boundary between text and data
+ * should not be the same as when the program was loaded.
+ * If NO_REMAP is defined, the argument data_start is ignored and the
+ * segment boundaries are never changed.
+ *
+ * Bss_start indicates how much of the data segment is to be saved in the
+ * a.out file and restored when the program is executed.  It gives the lowest
+ * unsaved address, and is rounded up to a page boundary.  The default when 0
+ * is given assumes that the entire data segment is to be stored, including
+ * the previous data and bss as well as any additional storage allocated with
+ * break (2).
+ *
+ * The new file is set up to start at entry_address.
+ *
+ * If you make improvements I'd like to get them too.
+ * harpo!utah-cs!thomas, thomas@Utah-20
+ *
+ */
+
+/* Modified to support SysVr3 shared libraries by James Van Artsdalen
+ * of Dell Computer Corporation.  [email protected].
+ */
+
+/* There are several compilation parameters affecting unexec:
+
+* COFF
+
+Define this if your system uses COFF for executables.
+Otherwise we assume you use Berkeley format.
+
+* NO_REMAP
+
+Define this if you do not want to try to save Emacs's pure data areas
+as part of the text segment.
+
+Saving them as text is good because it allows users to share more.
+
+However, on machines that locate the text area far from the data area,
+the boundary cannot feasibly be moved.  Such machines require
+NO_REMAP.
+
+Also, remapping can cause trouble with the built-in startup routine
+/lib/crt0.o, which defines `environ' as an initialized variable.
+Dumping `environ' as pure does not work!  So, to use remapping,
+you must write a startup routine for your machine in Emacs's crt0.c.
+If NO_REMAP is defined, Emacs uses the system's crt0.o.
+
+* SECTION_ALIGNMENT
+
+Some machines that use COFF executables require that each section
+start on a certain boundary *in the COFF file*.  Such machines should
+define SECTION_ALIGNMENT to a mask of the low-order bits that must be
+zero on such a boundary.  This mask is used to control padding between
+segments in the COFF file.
+
+If SECTION_ALIGNMENT is not defined, the segments are written
+consecutively with no attempt at alignment.  This is right for
+unmodified system V.
+
+* SEGMENT_MASK
+
+Some machines require that the beginnings and ends of segments
+*in core* be on certain boundaries.  For most machines, a page
+boundary is sufficient.  That is the default.  When a larger
+boundary is needed, define SEGMENT_MASK to a mask of
+the bits that must be zero on such a boundary.
+
+* A_TEXT_OFFSET(HDR)
+
+Some machines count the a.out header as part of the size of the text
+segment (a_text); they may actually load the header into core as the
+first data in the text segment.  Some have additional padding between
+the header and the real text of the program that is counted in a_text.
+
+For these machines, define A_TEXT_OFFSET(HDR) to examine the header
+structure HDR and return the number of bytes to add to `a_text'
+before writing it (above and beyond the number of bytes of actual
+program text).  HDR's standard fields are already correct, except that
+this adjustment to the `a_text' field has not yet been made;
+thus, the amount of offset can depend on the data in the file.
+  
+* A_TEXT_SEEK(HDR)
+
+If defined, this macro specifies the number of bytes to seek into the
+a.out file before starting to write the text segment.a
+
+* EXEC_MAGIC
+
+For machines using COFF, this macro, if defined, is a value stored
+into the magic number field of the output file.
+
+* ADJUST_EXEC_HEADER
+
+This macro can be used to generate statements to adjust or
+initialize nonstandard fields in the file header
+
+* ADDR_CORRECT(ADDR)
+
+Macro to correct an int which is the bit pattern of a pointer to a byte
+into an int which is the number of a byte.
+
+This macro has a default definition which is usually right.
+This default definition is a no-op on most machines (where a
+pointer looks like an int) but not on all machines.
+
+*/
+
+#ifndef emacs
+#define PERROR(arg) perror (arg); return -1
+#else
+#define IN_UNEXEC
+#include "config.h"
+#define PERROR(file) report_error (file, new)
+#endif
+
+#ifndef CANNOT_DUMP  /* all rest of file!  */
+
+#ifndef CANNOT_UNEXEC /* most of rest of file */
+
+#include <a.out.h>
+/* Define getpagesize () if the system does not.
+   Note that this may depend on symbols defined in a.out.h
+ */
+#include "getpagesize.h"
+
+#ifndef makedev			/* Try to detect types.h already loaded */
+#include <sys/types.h>
+#endif
+#include <stdio.h>
+#include <sys/stat.h>
+#include <errno.h>
+
+extern char *start_of_text ();		/* Start of text */
+extern char *start_of_data ();		/* Start of initialized data */
+
+#ifdef COFF
+static long block_copy_start;		/* Old executable start point */
+static struct filehdr f_hdr;		/* File header */
+static struct aouthdr f_ohdr;		/* Optional file header (a.out) */
+long bias;			/* Bias to add for growth */
+long lnnoptr;			/* Pointer to line-number info within file */
+#define SYMS_START block_copy_start
+
+static long text_scnptr;
+static long data_scnptr;
+
+#else /* not COFF */
+
+extern char *sbrk ();
+
+#define SYMS_START ((long) N_SYMOFF (ohdr))
+
+/* Some machines override the structure name for an a.out header.  */
+#ifndef EXEC_HDR_TYPE
+#define EXEC_HDR_TYPE struct exec
+#endif
+
+#ifdef HPUX
+#ifdef HP9000S200_ID
+#define MY_ID HP9000S200_ID
+#else
+#include <model.h>
+#define MY_ID MYSYS
+#endif /* no HP9000S200_ID */
+static MAGIC OLDMAGIC = {MY_ID, SHARE_MAGIC};
+static MAGIC NEWMAGIC = {MY_ID, DEMAND_MAGIC};
+#define N_TXTOFF(x) TEXT_OFFSET(x)
+#define N_SYMOFF(x) LESYM_OFFSET(x)
+static EXEC_HDR_TYPE hdr, ohdr;
+
+#else /* not HPUX */
+
+#if defined (USG) && !defined (IBMAIX) && !defined (IRIS)
+static struct bhdr hdr, ohdr;
+#define a_magic fmagic
+#define a_text tsize
+#define a_data dsize
+#define a_bss bsize
+#define a_syms ssize
+#define a_trsize rtsize
+#define a_drsize rdsize
+#define a_entry entry
+#define	N_BADMAG(x) \
+    (((x).fmagic)!=OMAGIC && ((x).fmagic)!=NMAGIC &&\
+     ((x).fmagic)!=FMAGIC && ((x).fmagic)!=IMAGIC)
+#define NEWMAGIC FMAGIC
+#else /* IRIS or IBMAIX or not USG */
+static EXEC_HDR_TYPE hdr, ohdr;
+#define NEWMAGIC ZMAGIC
+#endif /* IRIS or IBMAIX not USG */
+#endif /* not HPUX */
+
+static int unexec_text_start;
+static int unexec_data_start;
+
+#endif /* not COFF */
+
+static int pagemask;
+
+/* Correct an int which is the bit pattern of a pointer to a byte
+   into an int which is the number of a byte.
+   This is a no-op on ordinary machines, but not on all.  */
+
+#ifndef ADDR_CORRECT   /* Let m-*.h files override this definition */
+#define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
+#endif
+
+#ifdef emacs
+
+static
+report_error (file, fd)
+     char *file;
+     int fd;
+{
+  if (fd)
+    close (fd);
+  error ("Failure operating on %s\n", file);
+}
+#endif /* emacs */
+
+#define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
+#define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
+#define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
+
+static
+report_error_1 (fd, msg, a1, a2)
+     int fd;
+     char *msg;
+     int a1, a2;
+{
+  close (fd);
+#ifdef emacs
+  error (msg, a1, a2);
+#else
+  fprintf (stderr, msg, a1, a2);
+  fprintf (stderr, "\n");
+#endif
+}
+
+static int make_hdr ();
+static int copy_text_and_data ();
+static int copy_sym ();
+static void mark_x ();
+
+/* ****************************************************************
+ * unexec
+ *
+ * driving logic.
+ */
+unexec (new_name, a_name, data_start, bss_start, entry_address)
+     char *new_name, *a_name;
+     unsigned data_start, bss_start, entry_address;
+{
+  int new, a_out = -1;
+
+  if (a_name && (a_out = open (a_name, 0)) < 0)
+    {
+      PERROR (a_name);
+    }
+  if ((new = creat (new_name, 0666)) < 0)
+    {
+      PERROR (new_name);
+    }
+
+  if (make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name) < 0
+      || copy_text_and_data (new, a_out) < 0
+      || copy_sym (new, a_out, a_name, new_name) < 0
+#ifdef COFF
+#ifndef COFF_BSD_SYMBOLS
+      || adjust_lnnoptrs (new, a_out, new_name) < 0
+#endif
+#endif
+      )
+    {
+      close (new);
+      /* unlink (new_name);	    	/* Failed, unlink new a.out */
+      return -1;	
+    }
+
+  close (new);
+  if (a_out >= 0)
+    close (a_out);
+  mark_x (new_name);
+  return 0;
+}
+
+/* ****************************************************************
+ * make_hdr
+ *
+ * Make the header in the new a.out from the header in core.
+ * Modify the text and data sizes.
+ */
+static int
+make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name)
+     int new, a_out;
+     unsigned data_start, bss_start, entry_address;
+     char *a_name;
+     char *new_name;
+{
+  int tem;
+#ifdef COFF
+  auto struct scnhdr f_thdr;		/* Text section header */
+  auto struct scnhdr f_dhdr;		/* Data section header */
+  auto struct scnhdr f_bhdr;		/* Bss section header */
+  auto struct scnhdr scntemp;		/* Temporary section header */
+  register int scns;
+#endif /* COFF */
+#ifdef USG_SHARED_LIBRARIES
+  extern unsigned int bss_end;
+#else
+  unsigned int bss_end;
+#endif
+
+  pagemask = getpagesize () - 1;
+
+  /* Adjust text/data boundary. */
+#ifdef NO_REMAP
+  data_start = (int) start_of_data ();
+#else /* not NO_REMAP */
+  if (!data_start)
+    data_start = (int) start_of_data ();
+#endif /* not NO_REMAP */
+  data_start = ADDR_CORRECT (data_start);
+
+#ifdef SEGMENT_MASK
+  data_start = data_start & ~SEGMENT_MASK; /* (Down) to segment boundary. */
+#else
+  data_start = data_start & ~pagemask; /* (Down) to page boundary. */
+#endif
+
+  bss_end = ADDR_CORRECT (sbrk (0)) + pagemask;
+  bss_end &= ~ pagemask;
+
+  /* Adjust data/bss boundary. */
+  if (bss_start != 0)
+    {
+      bss_start = (ADDR_CORRECT (bss_start) + pagemask);
+      /* (Up) to page bdry. */
+      bss_start &= ~ pagemask;
+      if (bss_start > bss_end)
+	{
+	  ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
+		  bss_start);
+	}
+    }
+  else
+    bss_start = bss_end;
+
+  if (data_start > bss_start)	/* Can't have negative data size. */
+    {
+      ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
+	      data_start, bss_start);
+    }
+
+#ifdef COFF
+  /* Salvage as much info from the existing file as possible */
+  if (a_out >= 0)
+    {
+      if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
+	{
+	  PERROR (a_name);
+	}
+      block_copy_start += sizeof (f_hdr);
+      if (f_hdr.f_opthdr > 0)
+	{
+	  if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
+	    {
+	      PERROR (a_name);
+	    }
+	  block_copy_start += sizeof (f_ohdr);
+	}
+      /* Loop through section headers, copying them in */
+      for (scns = f_hdr.f_nscns; scns > 0; scns--) {
+	if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
+	  {
+	    PERROR (a_name);
+	  }
+	if (scntemp.s_scnptr > 0L)
+	  {
+            if (block_copy_start < scntemp.s_scnptr + scntemp.s_size)
+	      block_copy_start = scntemp.s_scnptr + scntemp.s_size;
+	  }
+	if (strcmp (scntemp.s_name, ".text") == 0)
+	  {
+	    f_thdr = scntemp;
+	  }
+	else if (strcmp (scntemp.s_name, ".data") == 0)
+	  {
+	    f_dhdr = scntemp;
+	  }
+	else if (strcmp (scntemp.s_name, ".bss") == 0)
+	  {
+	    f_bhdr = scntemp;
+	  }
+      }
+    }
+  else
+    {
+      ERROR0 ("can't build a COFF file from scratch yet");
+    }
+
+  /* Now we alter the contents of all the f_*hdr variables
+     to correspond to what we want to dump.  */
+
+#ifdef USG_SHARED_LIBRARIES
+
+  /* The amount of data we're adding to the file is distance from the
+   * end of the original .data space to the current end of the .data
+   * space.
+   */
+
+  bias = bss_end - (f_ohdr.data_start + f_dhdr.s_size);
+
+#endif
+
+  f_hdr.f_flags |= (F_RELFLG | F_EXEC);
+#ifdef TPIX
+  f_hdr.f_nscns = 3;
+#endif
+#ifdef EXEC_MAGIC
+  f_ohdr.magic = EXEC_MAGIC;
+#endif
+#ifndef NO_REMAP
+  f_ohdr.text_start = (long) start_of_text ();
+  f_ohdr.tsize = data_start - f_ohdr.text_start;
+  f_ohdr.data_start = data_start;
+#endif /* NO_REMAP */
+  f_ohdr.dsize = bss_start - f_ohdr.data_start;
+  f_ohdr.bsize = bss_end - bss_start;
+#ifndef KEEP_OLD_TEXT_SCNPTR
+  /* On some machines, the old values are right.
+     ??? Maybe on all machines with NO_REMAP.  */
+  f_thdr.s_size = f_ohdr.tsize;
+  f_thdr.s_scnptr = sizeof (f_hdr) + sizeof (f_ohdr);
+  f_thdr.s_scnptr += (f_hdr.f_nscns) * (sizeof (f_thdr));
+#endif /* KEEP_OLD_TEXT_SCNPTR */
+#ifdef ADJUST_TEXT_SCNHDR_SIZE
+  /* On some machines, `text size' includes all headers.  */
+  f_thdr.s_size -= f_thdr.s_scnptr;
+#endif /* ADJUST_TEST_SCNHDR_SIZE */
+  lnnoptr = f_thdr.s_lnnoptr;
+#ifdef SECTION_ALIGNMENT
+  /* Some systems require special alignment
+     of the sections in the file itself.  */
+  f_thdr.s_scnptr
+    = (f_thdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
+#endif /* SECTION_ALIGNMENT */
+#ifdef TPIX
+  f_thdr.s_scnptr = 0xd0;
+#endif
+  text_scnptr = f_thdr.s_scnptr;
+#ifdef ADJUST_TEXTBASE
+  text_scnptr = sizeof (f_hdr) + sizeof (f_ohdr) + (f_hdr.f_nscns) * (sizeof (f_thdr));
+#endif
+#ifndef KEEP_OLD_PADDR
+  f_dhdr.s_paddr = f_ohdr.data_start;
+#endif /* KEEP_OLD_PADDR */
+  f_dhdr.s_vaddr = f_ohdr.data_start;
+  f_dhdr.s_size = f_ohdr.dsize;
+  f_dhdr.s_scnptr = f_thdr.s_scnptr + f_thdr.s_size;
+#ifdef SECTION_ALIGNMENT
+  /* Some systems require special alignment
+     of the sections in the file itself.  */
+  f_dhdr.s_scnptr
+    = (f_dhdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
+#endif /* SECTION_ALIGNMENT */
+#ifdef DATA_SECTION_ALIGNMENT
+  /* Some systems require special alignment
+     of the data section only.  */
+  f_dhdr.s_scnptr
+    = (f_dhdr.s_scnptr + DATA_SECTION_ALIGNMENT) & ~DATA_SECTION_ALIGNMENT;
+#endif /* DATA_SECTION_ALIGNMENT */
+  data_scnptr = f_dhdr.s_scnptr;
+#ifndef KEEP_OLD_PADDR
+  f_bhdr.s_paddr = f_ohdr.data_start + f_ohdr.dsize;
+#endif /* KEEP_OLD_PADDR */
+  f_bhdr.s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
+  f_bhdr.s_size = f_ohdr.bsize;
+  f_bhdr.s_scnptr = 0L;
+#ifndef USG_SHARED_LIBRARIES
+  bias = f_dhdr.s_scnptr + f_dhdr.s_size - block_copy_start;
+#endif
+
+  if (f_hdr.f_symptr > 0L)
+    {
+      f_hdr.f_symptr += bias;
+    }
+
+  if (f_thdr.s_lnnoptr > 0L)
+    {
+      f_thdr.s_lnnoptr += bias;
+    }
+
+#ifdef ADJUST_EXEC_HEADER
+  ADJUST_EXEC_HEADER;
+#endif /* ADJUST_EXEC_HEADER */
+
+  if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
+    {
+      PERROR (new_name);
+    }
+
+  if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
+    {
+      PERROR (new_name);
+    }
+
+#ifndef USG_SHARED_LIBRARIES
+
+  if (write (new, &f_thdr, sizeof (f_thdr)) != sizeof (f_thdr))
+    {
+      PERROR (new_name);
+    }
+
+  if (write (new, &f_dhdr, sizeof (f_dhdr)) != sizeof (f_dhdr))
+    {
+      PERROR (new_name);
+    }
+
+  if (write (new, &f_bhdr, sizeof (f_bhdr)) != sizeof (f_bhdr))
+    {
+      PERROR (new_name);
+    }
+
+#else /* USG_SHARED_LIBRARIES */
+
+  /* The purpose of this code is to write out the new file's section
+   * header table.
+   *
+   * Scan through the original file's sections.  If the encountered
+   * section is one we know (.text, .data or .bss), write out the
+   * correct header.  If it is a section we do not know (such as
+   * .lib), adjust the address of where the section data is in the
+   * file, and write out the header.
+   *
+   * If any section preceeds .text or .data in the file, this code
+   * will not adjust the file pointer for that section correctly.
+   */
+
+  lseek (a_out, sizeof (f_hdr) + sizeof (f_ohdr), 0);
+
+  for (scns = f_hdr.f_nscns; scns > 0; scns--)
+    {
+      if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
+	PERROR (a_name);
+
+      if (!strcmp (scntemp.s_name, f_thdr.s_name))	/* .text */
+	{
+	  if (write (new, &f_thdr, sizeof (f_thdr)) != sizeof (f_thdr))
+	    PERROR (new_name);
+	}
+      else if (!strcmp (scntemp.s_name, f_dhdr.s_name))	/* .data */
+	{
+	  if (write (new, &f_dhdr, sizeof (f_dhdr)) != sizeof (f_dhdr))
+	    PERROR (new_name);
+	}
+      else if (!strcmp (scntemp.s_name, f_bhdr.s_name))	/* .bss */
+	{
+	  if (write (new, &f_bhdr, sizeof (f_bhdr)) != sizeof (f_bhdr))
+	    PERROR (new_name);
+	}
+      else
+	{
+	  if (scntemp.s_scnptr)
+	    scntemp.s_scnptr += bias;
+	  if (write (new, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
+	    PERROR (new_name);
+	}
+    }
+#endif /* USG_SHARED_LIBRARIES */
+
+  return (0);
+
+#else /* if not COFF */
+
+  /* Get symbol table info from header of a.out file if given one. */
+  if (a_out >= 0)
+    {
+      if (read (a_out, &ohdr, sizeof hdr) != sizeof hdr)
+	{
+	  PERROR (a_name);
+	}
+
+      if (N_BADMAG (ohdr))
+	{
+	  ERROR1 ("invalid magic number in %s", a_name);
+	}
+      hdr = ohdr;
+    }
+  else
+    {
+      bzero (hdr, sizeof hdr);
+    }
+
+  unexec_text_start = (long) start_of_text ();
+  unexec_data_start = data_start;
+
+  /* Machine-dependent fixup for header, or maybe for unexec_text_start */
+#ifdef ADJUST_EXEC_HEADER
+  ADJUST_EXEC_HEADER;
+#endif /* ADJUST_EXEC_HEADER */
+
+  hdr.a_trsize = 0;
+  hdr.a_drsize = 0;
+  if (entry_address != 0)
+    hdr.a_entry = entry_address;
+
+  hdr.a_bss = bss_end - bss_start;
+  hdr.a_data = bss_start - data_start;
+#ifdef NO_REMAP
+  hdr.a_text = ohdr.a_text;
+#else /* not NO_REMAP */
+  hdr.a_text = data_start - unexec_text_start;
+
+#ifdef A_TEXT_OFFSET
+  hdr.a_text += A_TEXT_OFFSET (ohdr);
+#endif
+
+#endif /* not NO_REMAP */
+
+  if (write (new, &hdr, sizeof hdr) != sizeof hdr)
+    {
+      PERROR (new_name);
+    }
+
+#ifdef A_TEXT_OFFSET
+  hdr.a_text -= A_TEXT_OFFSET (ohdr);
+#endif
+
+  return 0;
+
+#endif /* not COFF */
+}
+
+/* ****************************************************************
+ * copy_text_and_data
+ *
+ * Copy the text and data segments from memory to the new a.out
+ */
+static int
+copy_text_and_data (new, a_out)
+     int new, a_out;
+{
+  register char *end;
+  register char *ptr;
+
+#ifdef COFF
+
+#ifdef USG_SHARED_LIBRARIES
+
+  int scns;
+  struct scnhdr scntemp;		/* Temporary section header */
+
+  /* The purpose of this code is to write out the new file's section
+   * contents.
+   *
+   * Step through the section table.  If we know the section (.text,
+   * .data) do the appropriate thing.  Otherwise, if the section has
+   * no allocated space in the file (.bss), do nothing.  Otherwise,
+   * the section has space allocated in the file, and is not a section
+   * we know.  So just copy it.
+   */
+
+  lseek (a_out, sizeof (struct filehdr) + sizeof (struct aouthdr), 0);
+
+  for (scns = f_hdr.f_nscns; scns > 0; scns--)
+    {
+      if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
+	PERROR ("temacs");
+
+      if (!strcmp (scntemp.s_name, ".text"))
+	{
+	  lseek (new, (long) text_scnptr, 0);
+	  ptr = (char *) f_ohdr.text_start;
+	  end = ptr + f_ohdr.tsize;
+	  write_segment (new, ptr, end);
+	}
+      else if (!strcmp (scntemp.s_name, ".data"))
+	{
+	  lseek (new, (long) data_scnptr, 0);
+	  ptr = (char *) f_ohdr.data_start;
+	  end = ptr + f_ohdr.dsize;
+	  write_segment (new, ptr, end);
+	}
+      else if (!scntemp.s_scnptr)
+	; /* do nothing - no data for this section */
+      else
+	{
+	  char page[BUFSIZ];
+	  int size, n;
+	  long old_a_out_ptr = lseek (a_out, 0, 1);
+
+	  lseek (a_out, scntemp.s_scnptr, 0);
+	  for (size = scntemp.s_size; size > 0; size -= sizeof (page))
+	    {
+	      n = size > sizeof (page) ? sizeof (page) : size;
+	      if (read (a_out, page, n) != n || write (new, page, n) != n)
+		PERROR ("xemacs");
+	    }
+	  lseek (a_out, old_a_out_ptr, 0);
+	}
+    }
+
+#else /* COFF, but not USG_SHARED_LIBRARIES */
+
+  lseek (new, (long) text_scnptr, 0);
+  ptr = (char *) f_ohdr.text_start;
+#ifdef HEADER_INCL_IN_TEXT
+  /* For Gould UTX/32, text starts after headers */
+  ptr = (char *) (ptr + text_scnptr);
+#endif /* HEADER_INCL_IN_TEXT */
+  end = ptr + f_ohdr.tsize;
+  write_segment (new, ptr, end);
+
+  lseek (new, (long) data_scnptr, 0);
+  ptr = (char *) f_ohdr.data_start;
+  end = ptr + f_ohdr.dsize;
+  write_segment (new, ptr, end);
+
+#endif /* USG_SHARED_LIBRARIES */
+
+#else /* if not COFF */
+
+/* Some machines count the header as part of the text segment.
+   That is to say, the header appears in core
+   just before the address that start_of_text () returns.
+   For them, N_TXTOFF is the place where the header goes.
+   We must adjust the seek to the place after the header.
+   Note that at this point hdr.a_text does *not* count
+   the extra A_TEXT_OFFSET bytes, only the actual bytes of code.  */
+
+#ifdef A_TEXT_SEEK
+  lseek (new, (long) A_TEXT_SEEK (hdr), 0);
+#else
+  lseek (new, (long) N_TXTOFF (hdr), 0);
+#endif /* no A_TEXT_SEEK */
+
+  ptr = (char *) unexec_text_start;
+  end = ptr + hdr.a_text;
+  write_segment (new, ptr, end);
+
+  ptr = (char *) unexec_data_start;
+  end = ptr + hdr.a_data;
+/*  This lseek is certainly incorrect when A_TEXT_OFFSET
+    and I believe it is a no-op otherwise.
+    Let's see if its absence ever fails.  */
+/*  lseek (new, (long) N_TXTOFF (hdr) + hdr.a_text, 0); */
+  write_segment (new, ptr, end);
+
+#endif /* not COFF */
+
+  return 0;
+}
+
+write_segment (new, ptr, end)
+     int new;
+     register char *ptr, *end;
+{
+  register int i, nwrite, ret;
+  char buf[80];
+  extern int errno;
+  char zeros[128];
+
+  bzero (zeros, sizeof zeros);
+
+  for (i = 0; ptr < end;)
+    {
+      /* distance to next multiple of 128.  */
+      nwrite = (((int) ptr + 128) & -128) - (int) ptr;
+      /* But not beyond specified end.  */
+      if (nwrite > end - ptr) nwrite = end - ptr;
+      ret = write (new, ptr, nwrite);
+      /* If write gets a page fault, it means we reached
+	 a gap between the old text segment and the old data segment.
+	 This gap has probably been remapped into part of the text segment.
+	 So write zeros for it.  */
+      if (ret == -1 && errno == EFAULT)
+	write (new, zeros, nwrite);
+      else if (nwrite != ret)
+	{
+	  sprintf (buf,
+		   "unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d",
+		   ptr, new, nwrite, ret, errno);
+	  PERROR (buf);
+	}
+      i += nwrite;
+      ptr += nwrite;
+    }
+}
+
+/* ****************************************************************
+ * copy_sym
+ *
+ * Copy the relocation information and symbol table from the a.out to the new
+ */
+static int
+copy_sym (new, a_out, a_name, new_name)
+     int new, a_out;
+     char *a_name, *new_name;
+{
+  char page[1024];
+  int n;
+
+  if (a_out < 0)
+    return 0;
+
+#ifdef COFF
+  if (SYMS_START == 0L)
+    return 0;
+#endif  /* COFF */
+
+#ifdef COFF
+  if (lnnoptr)			/* if there is line number info */
+    lseek (a_out, lnnoptr, 0);	/* start copying from there */
+  else
+#endif /* COFF */
+    lseek (a_out, SYMS_START, 0);	/* Position a.out to symtab. */
+
+  while ((n = read (a_out, page, sizeof page)) > 0)
+    {
+      if (write (new, page, n) != n)
+	{
+	  PERROR (new_name);
+	}
+    }
+  if (n < 0)
+    {
+      PERROR (a_name);
+    }
+  return 0;
+}
+
+/* ****************************************************************
+ * mark_x
+ *
+ * After succesfully building the new a.out, mark it executable
+ */
+static void
+mark_x (name)
+     char *name;
+{
+  struct stat sbuf;
+  int um;
+  int new = 0;  /* for PERROR */
+
+  um = umask (777);
+  umask (um);
+  if (stat (name, &sbuf) == -1)
+    {
+      PERROR (name);
+    }
+  sbuf.st_mode |= 0111 & ~um;
+  if (chmod (name, sbuf.st_mode) == -1)
+    PERROR (name);
+}
+
+#ifdef COFF
+#ifndef COFF_BSD_SYMBOLS
+
+/*
+ *	If the COFF file contains a symbol table and a line number section,
+ *	then any auxiliary entries that have values for x_lnnoptr must
+ *	be adjusted by the amount that the line number section has moved
+ *	in the file (bias computed in make_hdr).  The #@$%&* designers of
+ *	the auxiliary entry structures used the absolute file offsets for
+ *	the line number entry rather than an offset from the start of the
+ *	line number section!
+ *
+ *	When I figure out how to scan through the symbol table and pick out
+ *	the auxiliary entries that need adjustment, this routine will
+ *	be fixed.  As it is now, all such entries are wrong and sdb
+ *	will complain.   Fred Fish, UniSoft Systems Inc.
+ */
+
+/* This function is probably very slow.  Instead of reopening the new
+   file for input and output it should copy from the old to the new
+   using the two descriptors already open (WRITEDESC and READDESC).
+   Instead of reading one small structure at a time it should use
+   a reasonable size buffer.  But I don't have time to work on such
+   things, so I am installing it as submitted to me.  -- RMS.  */
+
+adjust_lnnoptrs (writedesc, readdesc, new_name)
+     int writedesc;
+     int readdesc;
+     char *new_name;
+{
+  register int nsyms;
+  register int new;
+#ifdef amdahl_uts
+  SYMENT symentry;
+  AUXENT auxentry;
+#else
+  struct syment symentry;
+  union auxent auxentry;
+#endif
+
+  if (!lnnoptr || !f_hdr.f_symptr)
+    return 0;
+
+  if ((new = open (new_name, 2)) < 0)
+    {
+      PERROR (new_name);
+      return -1;
+    }
+
+  lseek (new, f_hdr.f_symptr, 0);
+  for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
+    {
+      read (new, &symentry, SYMESZ);
+      if (symentry.n_numaux)
+	{
+	  read (new, &auxentry, AUXESZ);
+	  nsyms++;
+	  if (ISFCN (symentry.n_type)) {
+	    auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
+	    lseek (new, -AUXESZ, 1);
+	    write (new, &auxentry, AUXESZ);
+	  }
+	}
+    }
+  close (new);
+}
+
+#endif /* COFF_BSD_SYMBOLS */
+
+#endif /* COFF */
+
+#endif /* not CANNOT_UNEXEC */
+
+#endif /* not CANNOT_DUMP */