/* Dump an executable image.
   Copyright (C) 1985, 1986, 1987, 1988 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: FSF 20.2. */

/* This file has been ... uhhhhh ... Mule-ized.  Yeah.

   (Everything here is external format.  That's potentially dangerous,
   but in practice it'll be OK.) --ben */

/* Originally based on the COFF unexec.c by Spencer W. Thomas.
 *
 * Subsequently hacked on by
 * Bill Mann <Bill_Man@praxisint.com>
 * Andrew Vignaux <Andrew.Vignaux@comp.vuw.ac.nz>
 * Mike Sperber <sperber@informatik.uni-tuebingen.de>
 *
 * 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.
 *
 * data_start and entry_address are ignored.
 *
 * 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
 * sbrk(2).
 *
 */

#ifndef emacs
#define PERROR(arg) perror (arg); return -1
#else
#include <config.h>
#define PERROR(file) report_error (file, new)
#endif

#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"

#include <sys/types.h>
#include <stdio.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>

extern char *start_of_text (void);		/* Start of text */
extern char *start_of_data (void);		/* Start of initialized data */

extern int _data;
extern int _text;

#include <filehdr.h>
#include <aouthdr.h>
#include <scnhdr.h>
#include <syms.h>

static struct filehdr f_hdr;		/* File header */
static struct aouthdr f_ohdr;		/* Optional file header (a.out) */
static long bias;			/* Bias to add for growth */
static long lnnoptr;			/* Pointer to line-number info within file */

static long text_scnptr;
static long data_scnptr;
#define ALIGN(val, pwr) (((val) + ((1L<<(pwr))-1)) & ~((1L<<(pwr))-1))
static long load_scnptr;
static long orig_load_scnptr;
static long orig_data_scnptr;
static int unrelocate_symbols (int, int, char *, char *);

#ifndef MAX_SECTIONS
#define MAX_SECTIONS	10
#endif

static int adjust_lnnoptrs (int, int, char *);

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
#include "lisp.h"

static void
report_error (char *file, int fd)
{
  if (fd)
    close (fd);
  report_error_with_errno (Qio_error, "Cannot unexec",
			   build_string (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 void
report_error_1 (int fd, char *msg, int a1, int a2)
{
  close (fd);
#ifdef emacs
  signal_ferror (Qio_error, msg, a1, a2);
#else
  fprintf (stderr, msg, a1, a2);
  fprintf (stderr, "\n");
#endif
}

static int make_hdr (int, int, unsigned, unsigned, unsigned, char *, char *);
static void mark_x (char *);
static int copy_text_and_data (int);
static int copy_sym (int, int, char *, char *);
static void write_segment (int, char *, char *);

/* ****************************************************************
 * unexec
 *
 * driving logic.
 */
int unexec (char *new_name, char *a_name,
	    uintptr_t data_start,
	    uintptr_t bss_start,
	    uintptr_t entry_address)
{
  int new = -1, a_out = -1;

  if (a_name && (a_out = open (a_name, O_RDONLY)) < 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) < 0
      || copy_sym (new, a_out, a_name, new_name) < 0
      || adjust_lnnoptrs (new, a_out, new_name) < 0
      || unrelocate_symbols (new, a_out, a_name, new_name) < 0)
    {
      close (new);
      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 (int new, int a_out,
	  unsigned data_start, unsigned bss_start,
	  unsigned entry_address,
	  char *a_name, char *new_name)
{
  int scns;
  unsigned int bss_end;

  struct scnhdr section[MAX_SECTIONS];
  struct scnhdr * f_thdr;		/* Text section header */
  struct scnhdr * f_dhdr;		/* Data section header */
  struct scnhdr * f_bhdr;		/* Bss section header */
  struct scnhdr * f_lhdr;		/* Loader section header */
  struct scnhdr * f_tchdr;		/* Typechk section header */
  struct scnhdr * f_dbhdr;		/* Debug section header */
  struct scnhdr * f_xhdr;		/* Except section header */

  load_scnptr = orig_load_scnptr = lnnoptr = 0;
  pagemask = getpagesize () - 1;

  /* Adjust text/data boundary. */
  data_start = (long) start_of_data ();
  data_start = ADDR_CORRECT (data_start);

  data_start = data_start & ~pagemask; /* (Down) to page boundary. */

  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);
    }

  /* Salvage as much info from the existing file as possible */
  f_thdr = NULL; f_dhdr = NULL; f_bhdr = NULL;
  f_lhdr = NULL; f_tchdr = NULL; f_dbhdr = NULL; f_xhdr = NULL;
  if (a_out >= 0)
    {
      if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
	{
	  PERROR (a_name);
	}
      if (f_hdr.f_opthdr > 0)
	{
	  if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
	    {
	      PERROR (a_name);
	    }
	}
      if (f_hdr.f_nscns > MAX_SECTIONS)
	{
	  ERROR0 ("unexec: too many section headers -- increase MAX_SECTIONS");
	}
      /* Loop through section headers */
      for (scns = 0; scns < f_hdr.f_nscns; scns++) {
	struct scnhdr *s = &section[scns];
	if (read (a_out, s, sizeof (*s)) != sizeof (*s))
	  {
	    PERROR (a_name);
	  }

#define CHECK_SCNHDR(ptr, name, flags) \
  if (strcmp(s->s_name, name) == 0) { \
    if (s->s_flags != flags) { \
      fprintf(stderr, "unexec: %lx flags where %x expected in %s section.\n", \
	      (unsigned long)s->s_flags, flags, name); \
    } \
    if (ptr) { \
      fprintf(stderr, "unexec: duplicate section header for section %s.\n", \
	      name); \
    } \
    ptr = s; \
  }
	CHECK_SCNHDR(f_thdr, _TEXT, STYP_TEXT);
	CHECK_SCNHDR(f_dhdr, _DATA, STYP_DATA);
	CHECK_SCNHDR(f_bhdr, _BSS, STYP_BSS);
	CHECK_SCNHDR(f_lhdr, _LOADER, STYP_LOADER);
	CHECK_SCNHDR(f_dbhdr, _DEBUG,  STYP_DEBUG);
	CHECK_SCNHDR(f_tchdr, _TYPCHK,  STYP_TYPCHK);
	CHECK_SCNHDR(f_xhdr, _EXCEPT,  STYP_EXCEPT);
      }

      if (f_thdr == 0)
	{
	  ERROR1 ("unexec: couldn't find \"%s\" section", (int) _TEXT);
	}
      if (f_dhdr == 0)
	{
	  ERROR1 ("unexec: couldn't find \"%s\" section", (int) _DATA);
	}
      if (f_bhdr == 0)
	{
	  ERROR1 ("unexec: couldn't find \"%s\" section", (int) _BSS);
	}
    }
  else
    {
      ERROR0 ("can't build a COFF file from scratch yet");
    }
  orig_data_scnptr = f_dhdr->s_scnptr;
  orig_load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;

  /* Now we alter the contents of all the f_*hdr variables
     to correspond to what we want to dump.  */

  /* Indicate that the reloc information is no longer valid for ld (bind);
     we only update it enough to fake out the exec-time loader.  */
  f_hdr.f_flags |= (F_RELFLG | F_EXEC);

  f_ohdr.dsize = bss_start - f_ohdr.data_start;
  f_ohdr.bsize = bss_end - bss_start;

  f_dhdr->s_size = f_ohdr.dsize;
  f_bhdr->s_size = f_ohdr.bsize;
  f_bhdr->s_paddr = f_ohdr.data_start + f_ohdr.dsize;
  f_bhdr->s_vaddr = f_ohdr.data_start + f_ohdr.dsize;

  /* fix scnptr's */
  {
    ulong ptr = section[0].s_scnptr;

    bias = -1;
    for (scns = 0; scns < f_hdr.f_nscns; scns++)
      {
	struct scnhdr *s = &section[scns];

	if (s->s_flags & STYP_PAD)        /* .pad sections omitted in AIX 4.1 */
	  {
	    /*
	     * the text_start should probably be o_algntext but that doesn't
	     * seem to change
	     */
	    if (f_ohdr.text_start != 0) /* && scns != 0 */
	      {
		s->s_size = 512 - (ptr % 512);
		if (s->s_size == 512)
		  s->s_size = 0;
	      }
	    s->s_scnptr = ptr;
	  }
	else if (s->s_flags & STYP_DATA)
	  s->s_scnptr = ptr;
	else if (!(s->s_flags & (STYP_TEXT | STYP_BSS)))
	  {
	    if (bias == -1)                /* if first section after bss */
	      bias = ptr - s->s_scnptr;

	    s->s_scnptr += bias;
	    ptr = s->s_scnptr;
	  }
  
	ptr = ptr + s->s_size;
      }
  }

  /* fix other pointers */
  for (scns = 0; scns < f_hdr.f_nscns; scns++)
    {
      struct scnhdr *s = &section[scns];

      if (s->s_relptr != 0)
	{
	  s->s_relptr += bias;
	}
      if (s->s_lnnoptr != 0)
	{
	  if (lnnoptr == 0) lnnoptr = s->s_lnnoptr;
	  s->s_lnnoptr += bias;
	}
    }

  if (f_hdr.f_symptr > 0L)
    {
      f_hdr.f_symptr += bias;
    }

  text_scnptr = f_thdr->s_scnptr;
  data_scnptr = f_dhdr->s_scnptr;
  load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;

  if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
    {
      PERROR (new_name);
    }

  if (f_hdr.f_opthdr > 0)
    {
      if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
	{
	  PERROR (new_name);
	}
    }

  for (scns = 0; scns < f_hdr.f_nscns; scns++) {
    struct scnhdr *s = &section[scns];
    if (write (new, s, sizeof (*s)) != sizeof (*s))
      {
	PERROR (new_name);
      }
  }

  return (0);
}

/* ****************************************************************
 
 *
 * Copy the text and data segments from memory to the new a.out
 */
static int
copy_text_and_data (int new)
{
  char *end;
  char *ptr;

  lseek (new, (long) text_scnptr, SEEK_SET);
  ptr = start_of_text () + text_scnptr;
  end = ptr + f_ohdr.tsize;
  write_segment (new, ptr, end);

  lseek (new, (long) data_scnptr, SEEK_SET);
  ptr = (char *) f_ohdr.data_start;
  end = ptr + f_ohdr.dsize;
  write_segment (new, ptr, end);

  return 0;
}

#define UnexBlockSz (1<<12)			/* read/write block size */
static void
write_segment (int new, char *ptr, char *end)
{
  int i, nwrite, ret;
  char buf[80];
  char zeros[UnexBlockSz];

  for (i = 0; ptr < end;)
    {
      /* distance to next block.  */
      nwrite = (((int) ptr + UnexBlockSz) & -UnexBlockSz) - (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)
	{
	  memset (zeros, 0, nwrite);
	  write (new, zeros, nwrite);
	}
      else if (nwrite != ret)
	{
	  sprintf (buf,
		   "unexec write failure: addr 0x%lx, fileno %d, size 0x%x, wrote 0x%x, errno %d",
		   (unsigned long)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 (int new, int a_out, char *a_name, char *new_name)
{
  char page[UnexBlockSz];
  int n;

  if (a_out < 0)
    return 0;

  if (orig_load_scnptr == 0L)
    return 0;

  if (lnnoptr && lnnoptr < orig_load_scnptr) /* if there is line number info  */
    lseek (a_out, lnnoptr, SEEK_SET);  /* start copying from there */
  else
    lseek (a_out, orig_load_scnptr, SEEK_SET); /* 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 successfully building the new a.out, mark it executable
 */
static void
mark_x (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);
}

static int
adjust_lnnoptrs (int writedesc, int readdesc, char *new_name)
{
  int nsyms;
  int naux;
  int new;
  struct syment symentry;
  union auxent auxentry;

  if (!lnnoptr || !f_hdr.f_symptr)
    return 0;

  if ((new = open (new_name, O_RDWR)) < 0)
    {
      PERROR (new_name);
      return -1;
    }

  lseek (new, f_hdr.f_symptr, SEEK_SET);
  for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
    {
      read (new, &symentry, SYMESZ);
      if (symentry.n_sclass == C_BINCL || symentry.n_sclass == C_EINCL)
	{
	  symentry.n_value += bias;
	  lseek (new, -SYMESZ, SEEK_CUR);
	  write (new, &symentry, SYMESZ);
	}

      for (naux = symentry.n_numaux; naux-- != 0; )
	{
	  read (new, &auxentry, AUXESZ);
	  nsyms++;
	  if (naux != 0              /* skip csect auxentry (last entry) */
              && (symentry.n_sclass == C_EXT || symentry.n_sclass == C_HIDEXT))
            {
              auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
              lseek (new, -AUXESZ, SEEK_CUR);
              write (new, &auxentry, AUXESZ);
            }
	}
    }
  close (new);

  return 0;
}

static int
unrelocate_symbols (int new, int a_out, char *a_name, char *new_name)
{
  int i;
  LDHDR ldhdr;
  LDREL ldrel;
  ulong t_reloc = (ulong) &_text - f_ohdr.text_start;
#ifndef ALIGN_DATA_RELOC
  ulong d_reloc = (ulong) &_data - f_ohdr.data_start;
#else
  /* This worked (and was needed) before AIX 4.2. 
     I have no idea why. -- Mike */
  ulong d_reloc = (ulong) &_data - ALIGN(f_ohdr.data_start, 2);
#endif
  int * p;

  if (load_scnptr == 0)
    return 0;

  lseek (a_out, orig_load_scnptr, SEEK_SET);
  if (read (a_out, &ldhdr, sizeof (ldhdr)) != sizeof (ldhdr))
    {
      PERROR (new_name);
    }

#define SYMNDX_TEXT	0
#define SYMNDX_DATA	1
#define SYMNDX_BSS	2

  for (i = 0; i < ldhdr.l_nreloc; i++)
    {
      lseek (a_out,
	     orig_load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
	     SEEK_SET);

      if (read (a_out, &ldrel, LDRELSZ) != LDRELSZ)
	{
	  PERROR (a_name);
	}

      /* move the BSS loader symbols to the DATA segment */
      if (ldrel.l_symndx == SYMNDX_BSS)
	{
	  ldrel.l_symndx = SYMNDX_DATA;

	  lseek (new,
		 load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
		 SEEK_SET);

	  if (write (new, &ldrel, LDRELSZ) != LDRELSZ)
	    {
	      PERROR (new_name);
	    }
	}

      if (ldrel.l_rsecnm == f_ohdr.o_sndata)
	{
	  int orig_int;

	  lseek (a_out,
                 orig_data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
		 SEEK_SET);

	  if (read (a_out, (void *) &orig_int, sizeof (orig_int))
	      != sizeof (orig_int))
	    {
	      PERROR (a_name);
	    }

          p = (int *) (ldrel.l_vaddr + d_reloc);

	  switch (ldrel.l_symndx) {
	  case SYMNDX_TEXT:
	    orig_int = * p - t_reloc;
	    break;

	  case SYMNDX_DATA:
	  case SYMNDX_BSS:
	    orig_int = * p - d_reloc;
	    break;
	  }

          if (orig_int != * p)
            {
              lseek (new,
                     data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
		     SEEK_SET);
              if (write (new, (void *) &orig_int, sizeof (orig_int))
                  != sizeof (orig_int))
                {
                  PERROR (new_name);
                }
            }
	}
    }
  return 0;
}