erl_marshal.c

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#ifdef DEBUG
  if (!ep) erl_err_msg("<ERROR> erl_decode: Error while decoding");
#endif
  return ep;

} /* erl_decode */

/* 
 * This one makes it possible to DECODE two CONSECUTIVE 
 * ETERM's in the same buffer. 
 */
ETERM *erl_decode_buf(unsigned char **ext) 
{
  ETERM *ep;
  
  /* We ignore the version magic since it might be
   * possible that the buffer has been manipulated
   * with erl_peek_ext.
   */
  if (**ext == ERL_VERSION_MAGIC) 
    (*ext)++;

  ep = NULL;
  ep = erl_decode_it(ext);
#ifdef DEBUG
    if (!ep) erl_err_msg("<ERROR> erl_decode_buf: Error while decoding");
#endif
  return ep;

} /* erl_decode_buf */


/*==============================================================
 * Ok, here comes routines for inspecting/manipulating 
 * an encoded buffer of bytes.
 *==============================================================
 */

/*
 * Return 1 if the VERSION MAGIC in the BUFFER is the
 * same as the this library version.
 */
int erl_verify_magic(unsigned char *ext)
{

  if (*ext == ERL_VERSION_MAGIC) 
    return 1;
  else
    return 0;

} /* erl_verify_magic */

/*
 * Return the TYPE of an ENCODED ETERM.
 * At failure, return 0.
 */ 
unsigned char erl_ext_type(unsigned char *ext)
{
    /* FIXME old code could skip multiple magic */

    /* Move over magic number if any */
    if (*ext == ERL_VERSION_MAGIC) ext++;
  
    switch (*ext) {
    case ERL_SMALL_INTEGER_EXT:
    case ERL_INTEGER_EXT:
	return ERL_INTEGER;
    case ERL_ATOM_EXT:
	return ERL_ATOM;
    case ERL_PID_EXT:
	return ERL_PID;
    case ERL_PORT_EXT:
	return ERL_PORT;
    case ERL_REFERENCE_EXT:
    case ERL_NEW_REFERENCE_EXT:
	return ERL_REF;
    case ERL_NIL_EXT: 
	return ERL_EMPTY_LIST;
    case ERL_LIST_EXT:
	return ERL_LIST;
    case ERL_SMALL_TUPLE_EXT:
    case ERL_LARGE_TUPLE_EXT:
	return ERL_TUPLE;
    case ERL_FLOAT_EXT:
	return ERL_FLOAT;
    case ERL_BINARY_EXT:
	return ERL_BINARY;
    case ERL_FUN_EXT:
    case ERL_NEW_FUN_EXT:
	return ERL_FUNCTION;
    case ERL_SMALL_BIG_EXT:
    case ERL_LARGE_BIG_EXT:
        return ERL_BIG;
    default:
	return 0;

    } /* switch */

} /* erl_ext_type */

/* 
 * Returns the number of elements in compund
 * terms. For other kind of terms zero is returned.
 * At failure -1 is returned.
 */
int erl_ext_size(unsigned char *t)
{
    int i;
    unsigned char *v;

    if (*t == ERL_VERSION_MAGIC) 
	return erl_ext_size(t+1);
 
    v = t+1;
    switch(*t) {
    case ERL_SMALL_INTEGER_EXT:
    case ERL_INTEGER_EXT:
    case ERL_ATOM_EXT:
    case ERL_PID_EXT:
    case ERL_PORT_EXT:
    case ERL_REFERENCE_EXT:
    case ERL_NEW_REFERENCE_EXT:
    case ERL_NIL_EXT: 
    case ERL_BINARY_EXT:
    case ERL_STRING_EXT:
    case ERL_FLOAT_EXT:
    case ERL_SMALL_BIG_EXT:
    case ERL_LARGE_BIG_EXT:
	return 0;
	break;
    case ERL_SMALL_TUPLE_EXT:
	i = v[0];
	return i;
	break;
    case ERL_LIST_EXT:
    case ERL_LARGE_TUPLE_EXT:
	i = (v[0] << 24) | (v[1] << 16) | (v[2] << 8) | v[3];
	return i;
	break;
    case ERL_FUN_EXT:
	i = (v[0] << 24) | (v[1] << 16) | (v[2] << 8) | v[3];
	return i+4;
	break;
    case ERL_NEW_FUN_EXT:
        v += 4 + 1 + 16 + 4;
	i = get32be(v);
	return i + 4;
	break;
    default:
	return -1;
	break;
    } /* switch */

} /* ext_size */

/*
 * A nice macro that eats up the atom pointed to.
 */
#define JUMP_ATOM(ext,i) \
if (**ext != ERL_ATOM_EXT) \
  return 0; \
*ext += 1; \
i = (**ext << 8) | (*ext)[1]; \
*ext += (i + 2)

/*
 * MOVE the POINTER PAST the ENCODED ETERM we
 * are currently pointing at. Returns 1 at
 * success, otherwise 0.
 */
static int jump(unsigned char **ext) 
{
    int j,k,i=0;
    int n;
    
    switch (*(*ext)++) {
    case ERL_VERSION_MAGIC:
	return jump(ext);
    case ERL_INTEGER_EXT:
	*ext += 4;
	break;
    case ERL_SMALL_INTEGER_EXT:
	*ext += 1;
	break;
    case ERL_ATOM_EXT:
	i = (**ext << 8) | (*ext)[1];
	*ext += (i + 2);
	break;
    case ERL_PID_EXT:
	/* eat first atom */
	JUMP_ATOM(ext,i);
	*ext += 9;		/* Two int's and the creation field */
	break;
    case ERL_REFERENCE_EXT:
    case ERL_PORT_EXT:
	/* first field is an atom */
	JUMP_ATOM(ext,i);
	*ext += 5;		/* One int and the creation field */
	break;
    case ERL_NEW_REFERENCE_EXT:
	n = (**ext << 8) | (*ext)[1];
	*ext += 2;
	/* first field is an atom */
	JUMP_ATOM(ext,i);
	*ext += 4*n+1;
	break;
    case ERL_NIL_EXT:
	/* We just passed it... */
	break;
    case ERL_LIST_EXT:
	i = j = 0;
	j = (**ext << 24) | ((*ext)[1] << 16) |((*ext)[2] << 8) | (*ext)[3];
	*ext += 4;	
	for(k=0; k<j; k++) 
	    if ((i = jump(ext)) == 0)
		return(0);
	if (**ext == ERL_NIL_EXT) {
	    *ext += 1;
	    break;
	}
	if (jump(ext) == 0) return 0;
	break;
    case ERL_STRING_EXT:
	i = **ext << 8 | (*ext)[1];
	*ext += 2 + i;
	break;
    case ERL_SMALL_TUPLE_EXT:
	i = *(*ext)++;
	goto jump_tuple;
    case ERL_LARGE_TUPLE_EXT:
	i = (**ext << 24) | ((*ext)[1] << 16) |((*ext)[2] << 8) | (*ext)[3];
	*ext += 4;
    jump_tuple:
	for (j = 0; j < i; j++) 
	    if ((k = jump(ext)) == 0)
		return(0);
	break;
    case ERL_FLOAT_EXT:
	*ext += 31;
	break;
    case ERL_BINARY_EXT:
	i = (**ext << 24) | ((*ext)[1] << 16) |((*ext)[2] << 8) | (*ext)[3];
	*ext += 4+i;
	break;
    case ERL_FUN_EXT:
	i = (**ext << 24) | ((*ext)[1] << 16) |((*ext)[2] << 8) | (*ext)[3];
	*ext += 4;
	i += 4;
	for (j = 0; j < i; j++)
	    if ((k = jump(ext)) == 0)
		return(0);
	break;
    case ERL_NEW_FUN_EXT:
	i = get32be(*ext);
	*ext += i + 4;
	break;
    case ERL_SMALL_BIG_EXT:
        i = *(*ext);
        *ext += i + 1;
        break;
    case ERL_LARGE_BIG_EXT:
	i = get32be(*ext);
        *ext += i + 4;
        break;
    default:
	return 0;
    } /* switch */

    return 1;

} /* jump */

/* 
 * The actual PEEK engine.
 */
static unsigned char *peek_ext(unsigned char **ext, int jumps)
{
  int i;

  switch (*(*ext)++) 
    {
    case ERL_VERSION_MAGIC:
      return peek_ext(ext, jumps);
    case ERL_SMALL_TUPLE_EXT:
      i = *(*ext)++;
      goto do_the_peek_stuff;
    case ERL_LARGE_TUPLE_EXT:
    case ERL_LIST_EXT:
      i = (**ext << 24) | ((*ext)[1]) << 16| ((*ext)[2]) << 8| ((*ext)[3]) ;  
      *ext += 4;
    do_the_peek_stuff:
      if (i <= jumps)   {
#ifdef DEBUG
	erl_err_msg("<ERROR> peek_ext: Out of range"); 
#endif
	return NULL;
      }
      for(i=0; i<jumps; i++)
	if (!jump(ext)) {
#ifdef DEBUG
	  erl_err_msg("<ERROR> peek_ext: Bad data"); 
#endif
	  return NULL;
	}
      return *ext;
    default:
#ifdef DEBUG
      erl_err_msg("<ERROR> peek_ext: Can't peek in non list/tuple type");
#endif
      return NULL;
    } /* switch */

} /* peek_ext */
	
/*
 * Return a POINTER TO the N:TH ELEMENT in a
 * COMPUND ENCODED ETERM.
 */
unsigned char *erl_peek_ext(unsigned char *ext, int jumps)
{
  unsigned char *x=ext;

  return peek_ext(&x, jumps);  

} /* erl_peek_ext */

/* 
 * Lexically compare two strings of bytes,
 * (string s1 length l1 and s2 l2).
 * Return: -1 if s1 < s2
 *	    0 if s1 = s2
 *	    1 if s1 > s2 
 */
static int cmpbytes(unsigned char* s1,int l1,unsigned char* s2,int l2)
{
  int i;
  i = 0;
  while((i < l1) && (i < l2)) {
    if (s1[i] < s2[i]) return(-1);
    if (s1[i] > s2[i]) return(1);
    i++;
  }
  if (l1 < l2) return(-1);
  if (l1 > l2) return(1);
  return(0);

} /* cmpbytes */

#define CMP_EXT_ERROR_CODE 4711

#define CMP_EXT_INT32_BE(AP, BP)				\
do {								\
    if ((AP)[0] != (BP)[0]) return (AP)[0] < (BP)[0] ? -1 : 1;	\
    if ((AP)[1] != (BP)[1]) return (AP)[1] < (BP)[1] ? -1 : 1;	\
    if ((AP)[2] != (BP)[2]) return (AP)[2] < (BP)[2] ? -1 : 1;	\
    if ((AP)[3] != (BP)[3]) return (AP)[3] < (BP)[3] ? -1 : 1;	\
} while (0)

#define CMP_EXT_SKIP_ATOM(EP)					\
do {								\
    if ((EP)[0] != ERL_ATOM_EXT)				\
	return CMP_EXT_ERROR_CODE;				\
    (EP) += 3 + ((EP)[1] << 8 | (EP)[2]);			\
} while (0)

/* 
 * We now know that both byte arrays are of the same type.
 */
static int compare_top_ext(unsigned char**, unsigned char **); /* forward */
static int cmp_exe2(unsigned char **e1, unsigned char **e2);

static int cmp_refs(unsigned char **e1, unsigned char **e2)
{
    int tmp, n1, n2;
    unsigned char *node1, *node2, *id1, *id2, cre1, cre2;

    if (*((*e1)++) == ERL_REFERENCE_EXT) {
	node1 = *e1;
	CMP_EXT_SKIP_ATOM(*e1);
	n1 = 1;
	id1 = *e1;
	cre1 = (*e1)[4];
	*e1 += 5;
    } else {
	n1 = get16be(*e1);
	node1 = *e1;
	CMP_EXT_SKIP_ATOM(*e1);
	cre1 = **e1;
	id1 = (*e1) + 1 + (n1 - 1)*4;
	*e1 = id1 + 4;
    }

    if (*((*e2)++) == ERL_REFERENCE_EXT) {
	node2 = *e2;
	CMP_EXT_SKIP_ATOM(*e2);
	n2 = 1;
	id2 = *e2;
	cre2 = (*e2)[4];
	*e2 += 5;
    } else {
	n2 = get16be(*e2);
	node2 = *e2;
	CMP_EXT_SKIP_ATOM(*e2);
	cre2 = **e2;
	id2 = (*e2) + 1 + (n2 - 1)*4;
	*e2 = id2 + 4;
    }

    /* First compare node names... */
    tmp = cmp_exe2(&node1, &node2);
    if (tmp != 0)
	return tmp;

    /* ... then creations ... */
    if (cre1 != cre2)
	return cre1 < cre2 ? -1 : 1;

    /* ... and then finaly ids. */
    if (n1 != n2) {
	unsigned char zero[] = {0, 0, 0, 0};
	if (n1 > n2)
	    do {
		CMP_EXT_INT32_BE(id1, zero);
		id1 -= 4;
		n1--;
	    } while (n1 > n2);
	else
	    do {
		CMP_EXT_INT32_BE(zero, id2);
		id2 -= 4;
		n2--;
	    } while (n2 > n1);
    }
    
    for (; n1 > 0; n1--, id1 -= 4, id2 -= 4)
	CMP_EXT_INT32_BE(id1, id2);

    return 0;
}

static int cmp_exe2(unsigned char **e1, unsigned char **e2)
{
  int min,  ret,i,j,k;
  double ff1, ff2;
  unsigned char *tmp1, *tmp2;

  *e2 += 1;
  switch (*(*e1)++) 
    {
    case ERL_SMALL_INTEGER_EXT:
      if (**e1 < **e2) ret = -1;
      else if (**e1 > **e2) ret = 1;
      else ret = 0;
      *e1 += 1; *e2 += 1;
      return ret;
    case ERL_INTEGER_EXT:
      i = (int) (**e1 << 24) | ((*e1)[1] << 16) |((*e1)[2] << 8) | (*e1)[3];
      j = (int) (**e2 << 24) | ((*e2)[1] << 16) |((*e2)[2] << 8) | (*e2)[3];
      if ( i < j) 
	ret = -1;
      else if ( i > j) 
	ret = 1;
      else 
	ret = 0;
      *e1 += 4; *e2 += 4;
      return ret;
    case ERL_ATOM_EXT:
      i = (**e1 << 8) | (*e1)[1];
      j = (**e2 << 8) | (*e2)[1];
      ret = cmpbytes(*e1 +2, i, *e2 +2, j);
      *e1 += (i + 2);
      *e2 += (j + 2);
      return ret;
    case ERL_PID_EXT: {
      unsigned char *n1 = *e1;
      unsigned char *n2 = *e2;
      CMP_EXT_SKIP_ATOM(*e1); CMP_EXT_SKIP_ATOM(*e2);
      *e1 += 9; *e2 += 9;

      /* First compare serials ... */
      tmp1 = *e1 - 5; tmp2 = *e2 - 5;