/* unexec for XEmacs on Cygwin32.
   Copyright (C) 1994, 1998 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.

*/

/* This is a complete rewrite, some code snarfed from unexnt.c and
   unexec.c, Andy Piper (andy@xemacs.org) 13-1-98 */

#include <config.h>
#include "lisp.h"

#include "sysfile.h"

#define PERROR(arg)				\
do {						\
  perror (arg);					\
  exit (-1);					\
} while (0)

#if !defined (HAVE_A_OUT_H) && !defined (WIN32_NATIVE)
unexec (char *, char *, void *, void *,	void *)
{
  PERROR ("cannot unexec() a.out.h not installed");
}
#else

#ifdef MINGW
#include <../../include/a.out.h>
#else
#include <a.out.h>
#endif

#define STACK_SIZE 0x800000
#define ALLOC_UNIT 0xFFFF
#define ALLOC_MASK ~((unsigned long) (ALLOC_UNIT))
#define ALIGN_ALLOC(addr) \
((((unsigned long) addr) + ALLOC_UNIT) & ALLOC_MASK)
/* Note that all sections must be aligned on a 0x1000 boundary so
   this is the minimum size that our dummy bss can be. */
#ifndef NO_DEBUG
#define BSS_PAD_SIZE	0x1000
#else
#define BSS_PAD_SIZE	0
#endif

/* To prevent zero-initialized variables from being placed into the bss
   section, use non-zero values to represent an uninitialized state.  */
#define UNINIT_PTR ((void *) 0xF0A0F0A0)
#define UNINIT_LONG (0xF0A0F0A0L)

static void get_section_info (int a_out, char* a_name);
static void copy_executable_and_dump_data_section (int a_out, int a_new);
static void dup_file_area (int a_out, int a_new, long size);
#if 0
static void write_int_to_bss (int a_out, int a_new, void* va, void* newval);
#endif

/* Cached info about the .data section in the executable.  */
void *data_start_va = UNINIT_PTR;
long data_size = UNINIT_LONG;

/* Cached info about the .bss section in the executable.  */
void *bss_start = UNINIT_PTR;
long bss_size = UNINIT_LONG;
int sections_reversed = 0;
FILHDR f_hdr;
PEAOUTHDR f_ohdr;
SCNHDR f_data, f_bss, f_text, f_nextdata;

#define CHECK_AOUT_POS(a)				\
do {							\
  if (lseek (a_out, 0, SEEK_CUR) != a)			\
    {							\
      printf ("we are at %lx, should be at %lx\n",	\
	      lseek (a_out, 0, SEEK_CUR), a);		\
      exit (-1);					\
    }							\
} while (0)

/* Dump out .data and .bss sections into a new executable.  */
int
unexec (char *out_name, char *in_name, uintptr_t start_data, 
	uintptr_t d1, uintptr_t d2)
{
  /* ugly nt hack - should be in lisp */
  int a_new, a_out = -1;
  char new_name[PATH_MAX], a_name[PATH_MAX];
  char *ptr;
  
  /* Make sure that the input and output filenames have the
     ".exe" extension...patch them up if they don't.  */
  strcpy (a_name, in_name);
  ptr = a_name + strlen (a_name) - 4;
  if (strcmp (ptr, ".exe"))
    strcat (a_name, ".exe");

  strcpy (new_name, out_name);
  ptr = new_name + strlen (new_name) - 4;
  if (strcmp (ptr, ".exe"))
    strcat (new_name, ".exe");

  /* We need to round off our heap to NT's allocation unit (64KB).  */
  /* round_heap (get_allocation_unit ()); */

  if (a_name && (a_out = open (a_name, O_RDONLY | OPEN_BINARY)) < 0)
    PERROR (a_name);

  if ((a_new = open (new_name, O_WRONLY | O_TRUNC | O_CREAT | OPEN_BINARY,
		     0755)) < 0)
    PERROR (new_name);

  /* Get the interesting section info, like start and size of .bss...  */
  get_section_info (a_out, a_name);

  copy_executable_and_dump_data_section (a_out, a_new);

  close (a_out);
  close (a_new);
  return 0;
}

/* Flip through the executable and cache the info necessary for dumping.  */
static void
get_section_info (int a_out, char* a_name)
{
  extern char my_ebss[];
  /* From lastfile.c  */
  extern char my_edata[];

  if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
    PERROR (a_name);

  if (f_hdr.e_magic != DOSMAGIC) 
    PERROR ("unknown exe header");

  /* Check the NT header signature ...  */
  if (f_hdr.nt_signature != NT_SIGNATURE) 
    PERROR ("invalid nt header");

  /* Flip through the sections for .data and .bss ...  */
  if (f_hdr.f_opthdr > 0)
    {
      if (read (a_out, &f_ohdr, AOUTSZ) != AOUTSZ)
	PERROR (a_name);
    }
  /* Loop through .data & .bss section headers, copying them in.
     With newer lds these are reversed so we have to cope with both */
  lseek (a_out, sizeof (f_hdr) + f_hdr.f_opthdr, 0);

  if (read (a_out, &f_text, sizeof (f_text)) != sizeof (f_text)
      || strcmp (f_text.s_name, ".text"))
    PERROR ("no .text section");

  /* The .bss section.  */
  if (read (a_out, &f_bss, sizeof (f_bss)) != sizeof (f_bss)
      || (strcmp (f_bss.s_name, ".bss") && strcmp (f_bss.s_name, ".data")))
    PERROR ("no .bss / .data section");

  /* check for reversed .bss and .data */
  if (!strcmp (f_bss.s_name, ".data"))
    {
      printf (".data and .bss reversed\n");
      sections_reversed = 1;
      memcpy (&f_data, &f_bss, sizeof (f_bss));
    }

  /* The .data section.  */
  if (!sections_reversed)
    {
      if (read (a_out, &f_data, sizeof (f_data)) != sizeof (f_data)
	  || strcmp (f_data.s_name, ".data"))
	PERROR ("no .data section");
    }
  else
    {
      if (read (a_out, &f_bss, sizeof (f_bss)) != sizeof (f_bss)
	  || strcmp (f_bss.s_name, ".bss"))
	PERROR ("no .bss section");
    }
  
  bss_start = (void *) ((char*)f_ohdr.ImageBase + f_bss.s_vaddr);
  bss_size = (unsigned long)((char*)&my_ebss-(char*)bss_start);
  
  /* must keep bss data that we want to be blank as blank */
  printf ("found bss - keeping %lx of %lx bytes\n", bss_size, f_ohdr.bsize);

  /* The .data section.  */
  data_start_va = (void *) ((char*)f_ohdr.ImageBase + f_data.s_vaddr);

  /* We want to only write Emacs data back to the executable,
     not any of the library data (if library data is included,
     then a dumped Emacs won't run on system versions other
     than the one Emacs was dumped on).  */
  data_size = (unsigned long)my_edata - (unsigned long)data_start_va;
  printf ("found data - keeping %lx of %lx bytes\n", data_size, f_ohdr.dsize);

  /* The following data section - often .idata */
  if (read (a_out, &f_nextdata, sizeof (f_nextdata)) != sizeof (f_nextdata)
      && strcmp (&f_nextdata.s_name[2], "data"))
    PERROR ("no other data section");
}

/* The dump routines.  */

static void
copy_executable_and_dump_data_section (int a_out, int a_new)
{
  long size = 0;
  /* NOTE: Some of these were previously declared as unsigned long,
     but the ones changed to long represent file sizes or pointers,
     which can't reasonably get above 2G. (A 2G executable???)
     Furthermore, some were even being compared as in if (x < 0) ... */
  long new_data_size, new_bss_size, bss_padding, file_sz_change;
  long data_padding = 0;
  long f_data_s_scnptr = f_data.s_scnptr;
  long f_nextdata_s_scnptr = f_nextdata.s_scnptr;
  unsigned long f_data_s_vaddr = f_data.s_vaddr;
  unsigned long f_bss_s_vaddr = f_bss.s_vaddr;

  int i;
  void* empty_space;
  extern int static_heap_dumped;
  SCNHDR section;
  /* calculate new sizes:
     
     f_ohdr.dsize is the total initialized data size on disk which is
     f_data.s_size + f_idata.s_size.
     
     f_ohdr.data_start is the base addres of all data and so should
     not be changed.
     
     *.s_vaddr is the virtual address of the start of the section
     *normalized from f_ohdr.ImageBase.
     
     *.s_paddr appears to be the number of bytes in the section
     *actually used (whereas *.s_size is aligned).
     
     bsize is now 0 since subsumed into .data
     dsize is dsize + (f_data.s_vaddr - f_bss.s_vaddr)
     f_data.s_vaddr is f_bss.s_vaddr
     f_data.s_size is new dsize maybe.
     what about s_paddr & s_scnptr?  */

  /* this is the amount the file increases in size */
  if (!sections_reversed)
    {
      new_bss_size = f_data.s_vaddr - f_bss.s_vaddr;
      data_padding = 0;
    }
  else
    {
      new_bss_size = f_nextdata.s_vaddr - f_bss.s_vaddr;
      data_padding = (f_bss.s_vaddr - f_data.s_vaddr) - f_data.s_size;
    }

  if ((new_bss_size - bss_size) < BSS_PAD_SIZE)
    PERROR (".bss free space too small");

  file_sz_change = (new_bss_size + data_padding) - BSS_PAD_SIZE;
  new_data_size = f_ohdr.dsize + file_sz_change;

  if (!sections_reversed)
    f_data.s_vaddr = f_bss.s_vaddr;
  f_data.s_paddr += file_sz_change;
#if 0 
  if (f_data.s_size + f_nextdata.s_size != f_ohdr.dsize)
    printf ("section size doesn't tally with dsize %lx != %lx\n", 
	   f_data.s_size + f_nextdata.s_size, f_ohdr.dsize);
#endif
  f_data.s_size += file_sz_change;
  lseek (a_new, 0, SEEK_SET);
  /* write file header */
  f_hdr.f_symptr += file_sz_change;
#ifdef NO_DEBUG
  f_hdr.f_nscns--;
#endif

  printf ("writing file header\n");
  if (write (a_new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
    PERROR ("failed to write file header");
  /* write optional header fixing dsize & bsize*/
  printf ("writing optional header\n");
  printf ("new data size is %lx, >= %lx\n", new_data_size,
	 f_ohdr.dsize + f_ohdr.bsize);
  if (new_data_size < (long) (f_ohdr.dsize + f_ohdr.bsize))
    printf ("warning: new data size is < approx\n");
  f_ohdr.dsize=new_data_size;
  f_ohdr.bsize=BSS_PAD_SIZE;
  /* Prevent stack overflow with regexp usage. */
  f_ohdr.SizeOfStackReserve = STACK_SIZE;

  if (write (a_new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
    PERROR ("failed to write optional header");
  /* write text as is */
  printf ("writing text header (unchanged)\n");

  if (write (a_new, &f_text, sizeof (f_text)) != sizeof (f_text))
    PERROR ("failed to write text header");
#ifndef NO_DEBUG
  /* Write small bss section. */
  if (!sections_reversed)
    {
      f_bss.s_size = BSS_PAD_SIZE;
      f_bss.s_paddr = BSS_PAD_SIZE;
      f_bss.s_vaddr = f_data.s_vaddr - BSS_PAD_SIZE;
      if (write (a_new, &f_bss, sizeof (f_bss)) != sizeof (f_bss))
	PERROR ("failed to write bss header");
    }
#endif
  /* write new data header */
  printf ("writing .data header\n");

  if (write (a_new, &f_data, sizeof (f_data)) != sizeof (f_data))
    PERROR ("failed to write data header");
#ifndef NO_DEBUG
  /* Write small bss section. */
  if (sections_reversed)
    {
      f_bss.s_size = BSS_PAD_SIZE;
      f_bss.s_paddr = BSS_PAD_SIZE;
      f_bss.s_vaddr = f_nextdata.s_vaddr - BSS_PAD_SIZE;
      if (write (a_new, &f_bss, sizeof (f_bss)) != sizeof (f_bss))
	PERROR ("failed to write bss header");
    }
#endif
  printf ("writing following data header\n");
  f_nextdata.s_scnptr += file_sz_change;
  if (f_nextdata.s_lnnoptr != 0) f_nextdata.s_lnnoptr += file_sz_change;
  if (f_nextdata.s_relptr != 0) f_nextdata.s_relptr += file_sz_change;
  if (write (a_new, &f_nextdata, sizeof (f_nextdata)) != sizeof (f_nextdata))
    PERROR ("failed to write nextdata header");

  /* copy other section headers adjusting the file offset */
  for (i=0; i<(f_hdr.f_nscns-3); i++)
    {
      if (read (a_out, &section, sizeof (section)) != sizeof (section))
	PERROR ("no .data section");
      
      section.s_scnptr += file_sz_change;
      if (section.s_lnnoptr != 0) section.s_lnnoptr += file_sz_change;
      if (section.s_relptr != 0) section.s_relptr += file_sz_change;

      if (write (a_new, &section, sizeof (section)) != sizeof (section))
	PERROR ("failed to write data header");
    }
#ifdef NO_DEBUG
  /* dump bss to maintain offsets */
  memset (&f_bss, 0, sizeof (f_bss));
  if (write (a_new, &f_bss, sizeof (f_bss)) != sizeof (f_bss))
    PERROR ("failed to write bss header");
#endif
  size = lseek (a_new, 0, SEEK_CUR);
  CHECK_AOUT_POS (size);

  /* copy eveything else until start of data */
  size = f_data_s_scnptr - lseek (a_out, 0, SEEK_CUR);

  printf ("copying executable up to data section ... %lx bytes\n", 
	  size);
  dup_file_area (a_out, a_new, size);

  CHECK_AOUT_POS (f_data_s_scnptr);

  if (!sections_reversed)
    {
      /* dump bss + padding between sections, sans small bss pad */
      printf ("dumping .bss into executable... %lx bytes\n", bss_size);
      if (write (a_new, bss_start, bss_size) != bss_size)
	{
	  PERROR ("failed to write bss section");
	}
      
      /* pad, needs to be zero */
      bss_padding = (new_bss_size - bss_size) - BSS_PAD_SIZE;
      if (bss_padding < 0)
	PERROR ("padded .bss too small");
      printf ("padding .bss ... %lx bytes\n", bss_padding);
      empty_space = malloc (bss_padding);
      memset (empty_space, 0, bss_padding);
      if (write (a_new, empty_space, bss_padding) != bss_padding)
	PERROR ("failed to write bss section");
      free (empty_space);
    }

  /* tell dumped version not to free pure heap */
  static_heap_dumped = 1;
  /* Get a pointer to the raw data in our address space.  */
  printf ("dumping .data section... %lx bytes\n", data_size);
  if (write (a_new, data_start_va, data_size) != data_size)
    PERROR ("failed to write data section");
  /* were going to use free again ... */
  static_heap_dumped = 0;
  
  size = lseek (a_out, f_data_s_scnptr + data_size, SEEK_SET);

  if (!sections_reversed)
    {
      size = f_nextdata_s_scnptr - size;
      dup_file_area (a_out, a_new, size);
    }
  else
    {
      /* need to pad to bss with data in file */
      printf ("padding .data ... %lx bytes\n", data_padding);
      size = (f_bss_s_vaddr - f_data_s_vaddr) - data_size;
      dup_file_area (a_out, a_new, size);

      /* dump bss + padding between sections */
      printf ("dumping .bss into executable... %lx bytes\n", bss_size);
      if (write (a_new, bss_start, bss_size) != bss_size)
	PERROR ("failed to write bss section");
      
      /* pad, needs to be zero */
      bss_padding = (new_bss_size - bss_size) - BSS_PAD_SIZE;
      if (bss_padding < 0)
	PERROR ("padded .bss too small");
      printf ("padding .bss ... %lx bytes\n", bss_padding);
      empty_space = malloc (bss_padding);
      memset (empty_space, 0, bss_padding);
      if (write (a_new, empty_space, bss_padding) != bss_padding)
	PERROR ("failed to write bss section");
      free (empty_space);
      if (lseek (a_new, 0, SEEK_CUR) != (long) f_nextdata.s_scnptr)
	{
	  printf ("at %lx should be at %lx\n", 
		 lseek (a_new, 0, SEEK_CUR),
		 f_nextdata.s_scnptr);
	  PERROR ("file positioning error\n");
	}
      lseek (a_out, f_nextdata_s_scnptr, SEEK_SET);
    }

  CHECK_AOUT_POS (f_nextdata_s_scnptr);

  /* now dump - nextdata don't need to do this cygwin ds is in .data! */
  printf ("dumping following data section... %lx bytes\n", f_nextdata.s_size);

  dup_file_area (a_out,a_new,f_nextdata.s_size);

  /* write rest of file */
  printf ("writing rest of file\n");
  size = lseek (a_out, 0, SEEK_END);
  size = size - (f_nextdata_s_scnptr + f_nextdata.s_size); /* length remaining in a_out */
  lseek (a_out, f_nextdata_s_scnptr + f_nextdata.s_size, SEEK_SET);

  dup_file_area (a_out, a_new, size);
}

/*
 * copy from aout to anew
 */
static void
dup_file_area (int a_out, int a_new, long size)
{
  char page[BUFSIZ];
  long n;
  for (; size > 0; size -= sizeof (page))
    {
      n = size > (long) sizeof (page) ? (long) sizeof (page) : size;
      if (read (a_out, page, n) != n || write (a_new, page, n) != n)
	PERROR ("dump_out()");
    }
}

#if 0
static void
write_int_to_bss (int a_out, int a_new, void* va, void* newval)
{
  int cpos;

  cpos = lseek (a_new, 0, SEEK_CUR);
  if (va < bss_start || va > bss_start + f_data.s_size)
    PERROR ("address not in data space\n");
  lseek (a_new, f_data.s_scnptr + ((unsigned long)va - 
				  (unsigned long)bss_start), SEEK_SET);
  if (write (a_new, newval, sizeof (int)) != (int) sizeof (int))
    PERROR ("failed to write int value");
  lseek (a_new, cpos, SEEK_SET);
}
#endif

#endif /* HAVE_A_OUT_H */