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/* Unexec for MIPS (including IRIS4D).
   Copyright (C) 1988 Free Software Foundation, Inc.

   Note that the GNU project considers support for MIPS operation
   a peripheral activity which should not be allowed to divert effort
   from development of the GNU system.  Changes in this code will be
   installed when users send them in, but aside from that
   we don't plan to think about it, or about whether other Emacs
   maintenance might break it.

    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 1, 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
    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., 675 Mass Ave, Cambridge, MA 02139, USA.

In other words, you are welcome to use, share and improve this program.
You are forbidden to forbid anyone else to use, share and improve
what you give them.   Help stamp out software-hoarding!  */
#include "config.h"
#include <sys/types.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <stdio.h>
#include <varargs.h>
#include <filehdr.h>
#include <aouthdr.h>
#include <scnhdr.h>
#include <sym.h>

#ifdef IRIS_4D
#include "getpagesize.h"
#include <fcntl.h>

static void fatal_unexec ();

#define READ(_fd, _buffer, _size, _error_message, _error_arg) \
	errno = EEOF; \
	if (read(_fd, _buffer, _size) != _size) \
	  fatal_unexec(_error_message, _error_arg);

#define WRITE(_fd, _buffer, _size, _error_message, _error_arg) \
	if (write(_fd, _buffer, _size) != _size) \
	  fatal_unexec(_error_message, _error_arg);

#define SEEK(_fd, _position, _error_message, _error_arg) \
	errno = EEOF; \
	if (lseek(_fd, _position, L_SET) != _position) \
	  fatal_unexec(_error_message, _error_arg);

extern int errno;
extern int sys_nerr;
extern char *sys_errlist[];
#define EEOF -1

static struct scnhdr *text_section;
static struct scnhdr *init_section;
static struct scnhdr *finit_section;
static struct scnhdr *rdata_section;
static struct scnhdr *data_section;
static struct scnhdr *lit8_section;
static struct scnhdr *lit4_section;
static struct scnhdr *sdata_section;
static struct scnhdr *sbss_section;
static struct scnhdr *bss_section;

struct headers {
    struct filehdr fhdr;
    struct aouthdr aout;
    struct scnhdr section[10];

/* Define name of label for entry point for the dumped executable.  */

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, old;
  int pagesize, brk;
  int newsyms, symrel;
  int nread;
  struct headers hdr;
  int i;
  int vaddr, scnptr;
#define BUFSIZE 8192
  char buffer[BUFSIZE];

  old = open (a_name, O_RDONLY, 0);
  if (old < 0) fatal_unexec ("opening %s", a_name);

  new = creat (new_name, 0666);
  if (new < 0) fatal_unexec ("creating %s", new_name);

  hdr = *((struct headers *)TEXT_START);
#ifdef MIPS2
  if (hdr.fhdr.f_magic != MIPSELMAGIC
      && hdr.fhdr.f_magic != MIPSEBMAGIC
      && hdr.fhdr.f_magic != (MIPSELMAGIC | 1)
      && hdr.fhdr.f_magic != (MIPSEBMAGIC | 1))
	      "unexec: input file magic number is %x, not %x, %x, %x or %x.\n",
#else /* not MIPS2 */
  if (hdr.fhdr.f_magic != MIPSELMAGIC
      && hdr.fhdr.f_magic != MIPSEBMAGIC)
      fprintf(stderr, "unexec: input file magic number is %x, not %x or %x.\n",
	      hdr.fhdr.f_magic, MIPSELMAGIC, MIPSEBMAGIC);
#endif /* not MIPS2 */
  if (hdr.fhdr.f_opthdr != sizeof(hdr.aout))
      fprintf(stderr, "unexec: input a.out header is %d bytes, not %d.\n",
	      hdr.fhdr.f_opthdr, sizeof(hdr.aout));
  if (hdr.aout.magic != ZMAGIC)
      fprintf(stderr, "unexec: input file a.out magic number is %o, not %o.\n",
	      hdr.aout.magic, ZMAGIC);

#define CHECK_SCNHDR(ptr, name, flags) \
  if (strcmp(hdr.section[i].s_name, name) == 0) { \
    if (hdr.section[i].s_flags != flags) { \
      fprintf(stderr, "unexec: %x flags where %x expected in %s section.\n", \
	      hdr.section[i].s_flags, flags, name); \
    } \
    ptr = hdr.section + i; \
    i += 1; \
  } \
  else { \
    ptr = NULL; \

  i = 0;
  CHECK_SCNHDR(text_section,  _TEXT,  STYP_TEXT);
  CHECK_SCNHDR(init_section,  _INIT,  STYP_INIT);
  CHECK_SCNHDR(rdata_section, _RDATA, STYP_RDATA);
  CHECK_SCNHDR(data_section,  _DATA,  STYP_DATA);
#ifdef _LIT8
  CHECK_SCNHDR(lit8_section,  _LIT8,  STYP_LIT8);
  CHECK_SCNHDR(lit4_section,  _LIT4,  STYP_LIT4);
#endif /* _LIT8 */
  CHECK_SCNHDR(sdata_section, _SDATA, STYP_SDATA);
  CHECK_SCNHDR(sbss_section,  _SBSS,  STYP_SBSS);
  CHECK_SCNHDR(bss_section,   _BSS,   STYP_BSS);
  if (i != hdr.fhdr.f_nscns)
    fprintf(stderr, "unexec: %d sections found instead of %d.\n",
	    i, hdr.fhdr.f_nscns);

  pagesize = getpagesize();
  brk = (sbrk(0) + pagesize - 1) & (-pagesize);
  hdr.aout.dsize = brk - DATA_START;
  hdr.aout.bsize = 0;
  if (entry_address == 0)
      hdr.aout.entry = (unsigned)DEFAULT_ENTRY_ADDRESS;
    hdr.aout.entry = entry_address;

  hdr.aout.bss_start = hdr.aout.data_start + hdr.aout.dsize;
  rdata_section->s_size = data_start - DATA_START;
  data_section->s_vaddr = data_start;
  data_section->s_paddr = data_start;
  data_section->s_size = brk - DATA_START;
  data_section->s_scnptr = rdata_section->s_scnptr + rdata_section->s_size;
  vaddr = data_section->s_vaddr + data_section->s_size;
  scnptr = data_section->s_scnptr + data_section->s_size;
  if (lit8_section != NULL)
      lit8_section->s_vaddr = vaddr;
      lit8_section->s_paddr = vaddr;
      lit8_section->s_size = 0;
      lit8_section->s_scnptr = scnptr;
  if (lit4_section != NULL)
      lit4_section->s_vaddr = vaddr;
      lit4_section->s_paddr = vaddr;
      lit4_section->s_size = 0;
      lit4_section->s_scnptr = scnptr;
  if (sdata_section != NULL)
      sdata_section->s_vaddr = vaddr;
      sdata_section->s_paddr = vaddr;
      sdata_section->s_size = 0;
      sdata_section->s_scnptr = scnptr;
  if (sbss_section != NULL)
      sbss_section->s_vaddr = vaddr;
      sbss_section->s_paddr = vaddr;
      sbss_section->s_size = 0;
      sbss_section->s_scnptr = scnptr;
  if (bss_section != NULL)
      bss_section->s_vaddr = vaddr;
      bss_section->s_paddr = vaddr;
      bss_section->s_size = 0;
      bss_section->s_scnptr = scnptr;

  WRITE(new, TEXT_START, hdr.aout.tsize,
	"writing text section to %s", new_name);
  WRITE(new, DATA_START, hdr.aout.dsize,
	"writing text section to %s", new_name);

  SEEK(old, hdr.fhdr.f_symptr, "seeking to start of symbols in %s", a_name);
  errno = EEOF;
  nread = read(old, buffer, BUFSIZE);
  if (nread < sizeof(HDRR)) fatal_unexec("reading symbols from %s", a_name);
#define symhdr ((pHDRR)buffer)
  newsyms = hdr.aout.tsize + hdr.aout.dsize;
  symrel = newsyms - hdr.fhdr.f_symptr;
  hdr.fhdr.f_symptr = newsyms;
  symhdr->cbLineOffset += symrel;
  symhdr->cbDnOffset += symrel;
  symhdr->cbPdOffset += symrel;
  symhdr->cbSymOffset += symrel;
  symhdr->cbOptOffset += symrel;
  symhdr->cbAuxOffset += symrel;
  symhdr->cbSsOffset += symrel;
  symhdr->cbSsExtOffset += symrel;
  symhdr->cbFdOffset += symrel;
  symhdr->cbRfdOffset += symrel;
  symhdr->cbExtOffset += symrel;
#undef symhdr
      if (write(new, buffer, nread) != nread)
	fatal_unexec("writing symbols to %s", new_name);
      nread = read(old, buffer, BUFSIZE);
      if (nread < 0) fatal_unexec("reading symbols from %s", a_name);
#undef BUFSIZE
    } while (nread != 0);

  SEEK(new, 0, "seeking to start of header in %s", new_name);
  WRITE(new, &hdr, sizeof(hdr),
	"writing header of %s", new_name);

 * mark_x
 * After succesfully building the new a.out, mark it executable

mark_x (name)
     char *name;
  struct stat sbuf;
  int um = umask (777);
  umask (um);
  if (stat (name, &sbuf) < 0)
    fatal_unexec ("getting protection on %s", name);
  sbuf.st_mode |= 0111 & ~um;
  if (chmod (name, sbuf.st_mode) < 0)
    fatal_unexec ("setting protection on %s", name);

static void
fatal_unexec (s, va_alist)
  va_list ap;
  if (errno == EEOF)
    fputs ("unexec: unexpected end of file, ", stderr);
  else if (errno < sys_nerr)
    fprintf (stderr, "unexec: %s, ", sys_errlist[errno]);
    fprintf (stderr, "unexec: error code %d, ", errno);
  va_start (ap);
  _doprnt (s, ap, stderr);
  fputs (".\n", stderr);
  exit (1);