unexmips.c 8.83 KB
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/* Unexec for MIPS (including IRIS4D).
   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.

   Copyright (C) 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.  */


#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"
#endif

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.  */

#ifndef DEFAULT_ENTRY_ADDRESS
#define DEFAULT_ENTRY_ADDRESS __start
#endif

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))
    {
      fprintf(stderr,
	      "unexec: input file magic number is %x, not %x, %x, %x or %x.\n",
	      hdr.fhdr.f_magic,
	      MIPSELMAGIC, MIPSEBMAGIC,
	      MIPSELMAGIC | 1, MIPSEBMAGIC | 1);
      exit(1);
    }
#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);
      exit (1);
    }
#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));
      exit (1);
    }
  if (hdr.aout.magic != ZMAGIC)
    {
      fprintf (stderr, "unexec: input file a.out magic number is %o, not %o.\n",
	       hdr.aout.magic, ZMAGIC);
      exit (1);
    }

#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 (%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)
    {
      extern DEFAULT_ENTRY_ADDRESS ();
      hdr.aout.entry = (unsigned)DEFAULT_ENTRY_ADDRESS;
    }
  else
    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;
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  data_section->s_size = brk - data_start;
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  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
  do
    {
      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);

  close (old);
  close (new);
  mark_x (new_name);
}

/*
 * mark_x
 *
 * After succesfully building the new a.out, mark it executable
 */

static
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_dcl
{
  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]);
  else
    fprintf (stderr, "unexec: error code %d, ", errno);
  va_start (ap);
  _doprnt (s, ap, stderr);
  fputs (".\n", stderr);
  exit (1);
}