postmort.c

操作系统源代码

  buff[9] = '$';
  (void) binary((int) uc, buff + 10);

  /* Print all the information */
  printf("Stack Frame:\tPC = %04.4x\t\t   PSW = %s\n",
         sp->pc, buff);
  printf("\t\t\t\t\tStatus = ____ ODIT SZ_A _P_C\n");

  printf("  ax	bx	cx	dx	di	si\n");
  printf("  %04.4x\t%04.4x\t%04.4x\t%04.4x\t%04.4x\t%04.4x\n",
         sp->retreg, sp->bx, sp->cx, sp->dx, sp->di, sp->si);
  printf("  sp	bp	ss\n");
  printf("  %04.4x\t%04.4x\t%04.4x\n",
         sp->sp, sp->fp, sp->ss);
  printf("  cs	ds	es\n");
  printf("  %04.4x\t%04.4x\t%04.4x\n",
         sp->cs, sp->ds, sp->es);

  /* Store for future reference */
  stackptr = sp->sp;
  baseptr = sp->fp;
  if (dbglvl > 0)
	printf("\nStack pointer 0x%x, Base pointer 0x%x\n", stackptr, baseptr);
}


/* M a i n
 *
 * Main program
 */
main(argc, argv)
int argc;
char *argv[];
{
  int j, fdc, fds;
  char *cp, corefile[132], symbfile[132];
  struct proc proc_entry;
  struct mem_map mp_segs[NR_SEGS];

  /* Initial set up */
  if ((cp = strrchr(argv[0], '/')) == (char *) NULL)
	cp = argv[0];
  else
	cp++;
  strncpy(progname, cp, 19);
  strncpy(corefile, CORE, 131);
  strncpy(symbfile, AOUT, 131);

  /* Parse arguments */
  opterr = 0;
  while ((j = getopt(argc, argv, "c:dps:tx:")) != EOF) {
	switch (j & 0177) {
	    case 'c':
		opt_c = TRUE;
		strncpy(corefile, optarg, 131);
		break;
	    case 'd':	opt_d = TRUE;	break;
	    case 'p':	opt_p = TRUE;	break;
	    case 's':
		opt_s = TRUE;
		strncpy(symbfile, optarg, 131);
		break;
	    case 't':	opt_t = TRUE;	break;
	    case 'x':
		dbglvl = atoi(optarg);
		opt_x = TRUE;
		break;
	    case '?':
	    default:
		usage();
		exit(1);
		break;
	}
  }

  /* We must have a core file */
  if ((fdc = open(corefile, O_RDONLY)) == -1) {
	fprintf(stderr, "Cannot open %s\n", corefile);
	exit(1);
  }

  /* We'd like an a.out file or a symbol table */
  if ((fds = open(symbfile, O_RDONLY)) == -1) {
	if (opt_s)
		j = FAILED;
	else {
		strncpy(symbfile, AOUT, 131);
		if ((fds = open(symbfile, O_RDONLY)) == -1)
			j = FAILED;
		else
			j = read_symbol(fds);
	}
  } else
	j = read_symbol(fds);

  /* Only fatal if we insisted */
  if (opt_s && j == FAILED) {
	fprintf(stderr, "Cannot find symbols in %s\n", symbfile);
	exit(1);
  }

  /* Read the process table */
  if (dbglvl > 0) {
	printf("\n");
	printf("Size of mproc entry %d\n", NR_SEGS * sizeof(struct mem_map));
	printf("Size of process table %d\n", sizeof(proc_entry));
  }
  if (read(fdc, (char *) mp_segs, sizeof(mp_segs)) != sizeof(mp_segs) ||
      read(fdc, (char *) &proc_entry,
	 sizeof(struct proc)) != sizeof(struct proc)) {
	fprintf(stderr, "Cannot open %s\n", corefile);
	exit(1);
  }

  /* Do the work */
#if 0
  dump_maps(mp_segs);		/* duplicated in the kernel */
  printf("\n");
#endif
  dump_maps(proc_entry.p_map);
  printf("\n");
  dump_registers(&proc_entry);
  if (opt_t) {
	printf("\n");
	stack_trace(fdc);
  }
  if (opt_p) {
	printf("\n");
	dump_proc_table(&proc_entry);
  }
  if (opt_d) {
	printf("\n");
	dump_sym_tab(symtab);
	dump_all_segs(fdc);
  }

  /* Wrap up */
  (void) close(fdc);
  if (fds != -1) (void) close(fds);

  exit(0);
  /* NOTREACHED */
}


/* P a r s e _ l i n e
 *
 * Parse a line of the symbol table
 */
int parse_line(ps)
char *ps;
{
  char c, s[80];
  int j, k;
  unsigned int u;

  /* We must have space in the table */
  if (maxsym == MAXSYM) return(FAILED);

  /* Lines must be a minimum length to contain information */
  if (strlen(ps) < 8) return(FAILED);

  /* Lines must have a definite structure */
  if (ps[1] != ' ' || ps[6] != ' ') return(FAILED);
  for (j = 2; j < 6; j++)
	if (!isxdigit(ps[j])) return(FAILED);
  if (sscanf(ps, "%c %x %s", &c, &u, s) != 3) return (FAILED);

  if (dbglvl > 0) printf("Address 0x%04.4x, label %s\n", u, s);

  /* Load the symbol table in sorted order */
  for (j = 0; j < maxsym; j++) {
	if (u < symtab[j].addr) {
		for (k = maxsym; k > j; k--) symtab[k] = symtab[k - 1];
		break;
	}
  }
  symtab[j].addr = u;
  strncpy(symtab[j].label, s, SYMLEN);
  maxsym++;

  return(OK);
}


/* R e a d _ s y m b o l
 *
 * Read the symbol table
 */
int read_symbol(fd)
int fd;
{
  char sym[80], buff[BUFSIZ];
  int j, k, m;
  long int offset;
  struct exec *ep;
  struct nlist *np;

  /* We collect only text symbols, since that's all that's needed here */

  /* Initialise the buffer */
  if ((j = read(fd, buff, BUFSIZ)) == 0 || j == -1) return(FAILED);

  k = maxsym = 0;

  /* Find out what we've got */
  ep = (struct exec *) buff;
  np = (struct nlist *) buff;
  if (BADMAG(*ep)) {
	/* Must be a separate symbol table */
	while (TRUE) {
		if (buff[k] == 'T') {
			for (m = 0; m < 78; m++) {
				sym[m] = buff[k];
				if (++k == j) {
					if ((j = read(fd, buff, BUFSIZ)) == 0 || j == -1)
						break;
					k = 0;
				}
				if (buff[k] == '\n') break;
			}
			sym[m + 1] = '\0';
			(void) parse_line(sym);
		}
		if (++k == j) {
			if ((j = read(fd, buff, BUFSIZ)) == 0 || j == -1)
				break;
			k = 0;
		}
	}
  } else if (ep->a_syms != 0L) {
	/* There's symbols in them thar hills */
	offset = 8 * sizeof(long) + ep->a_text + ep->a_data;
	if (lseek(fd, offset, 0) == -1L) return(FAILED);
	/* Symbols are in an unsorted list */
	while (read(fd, buff, sizeof(struct nlist)) == sizeof(struct nlist)) {
		if (np->n_sclass == (N_TEXT + C_EXT)) {	/* external text symbols */
			for (j = 0; j < maxsym; j++) {
				if (np->n_value < symtab[j].addr) {
					for (k = maxsym; k > j; k--)
						symtab[k] = symtab[k - 1];
					break;
				}
			}
			symtab[j].addr = np->n_value;
			strncpy(symtab[j].label, np->n_name, SYMLEN);
			if (maxsym++ == MAXSYM) break;
		}
	}
  } else if (opt_s)
	return(FAILED);

  if (dbglvl > 0) {
	for (m = 0; m < maxsym; m++) printf("Addr 0x%04.4x, label %s\n",
		       symtab[m].addr, symtab[m].label);
	printf("Maxsym %d\n", maxsym);
  }
  return(OK);
}


/* S t a c k _ t r a c e
 *
 * Trace back down the stack frames.
 *
 * WARNING: very, very, non-portable code
 */
void stack_trace(fd)
int fd;
{
  int j;
  unsigned int framepointer, lastpointer, returnvalue, end;
  long int offset, bp;

  /* Bp actually gives the offset from the base of the data segment */
  bp = (long) (NR_SEGS * sizeof(struct mem_map)) + sizeof(struct proc)
	+ lengths[0] + lengths[1] - bases[2];
  if ((offset = lseek(fd, bp + (long int) baseptr, 0)) == -1L) return;
  end = (bases[2] + lengths[2] - 1) & 0xffff;

  if (dbglvl > 0)
	printf("Baseptr %x, End %x, Bp %ld, Offset %ld\n", baseptr, end, bp, offset);

  /* Print the header, then try to backtrace  */
  printf("Stack back trace:\n\n");
  printf("Frame address.  Contents.  Return address.");
  if (maxsym != 0) printf("  Previous label.");
  printf("\n");

  lastpointer = baseptr;
  while (TRUE) {
	/* Read the frame pointer and return address values */
	if (read(fd, (char *) &framepointer, sizeof(int)) == -1 ||
	    read(fd, (char *) &returnvalue, sizeof(int)) == -1)
		break;

	/* Look up the return address - ignored if maxsym == 0 */
	for (j = 0; j < maxsym; j++) {
		if (symtab[j].addr >= returnvalue) break;
	}
	if (j > 0) j--;
	printf("    0x%04.4x        0x%04.4x      0x%04.4x          %s\n",
	       lastpointer, framepointer, returnvalue,
	       (maxsym == 0) ? "" : symtab[j].label);

	/* If the result is clearly invalid, quit */
	if (framepointer == 0 || framepointer >= end || framepointer <= lastpointer)
		break;

	/* Otherwise try to move to the next frame base */
	lastpointer = framepointer;
	if ((offset = lseek(fd, bp + (long int) framepointer, 0)) == -1L || offset == 0L)
		break;
  }
}


/* U s a g e
 *
 * Usage message
 */
void usage()
{
  fprintf(stderr, "Usage: %s [-dpt] [-c corefile] [-s symbfile]\n", progname);
}