py_tdbpack.c

来自「samba-3.0.22.tar.gz 编译smb服务器的源码」· C语言 代码 · 共 723 行 · 第 1/2 页

		if (!(nul_str = PyString_FromStringAndSize("", 1)))
			goto out;

	if ((PyList_Append(packed_list, coded_str) != -1)
	    && (PyList_Append(packed_list, nul_str) != -1))
		new_list = packed_list;

  out:
	Py_XDECREF(val_obj);
	Py_XDECREF(unicode_obj);
	Py_XDECREF(coded_str);

	return new_list;
}


/*
 * Pack (LENGTH, BUFFER) pair onto the list.
 *
 * The buffer must already be a String, not Unicode, because it contains 8-bit
 * untranslated data.  In some cases it will actually be UTF_16_LE data.
 */
static PyObject *
pytdbpack_buffer(PyObject *val_iter, PyObject *packed_list)
{
	PyObject *val_obj;
	PyObject *new_list = NULL;
	
	/* pull off integer and stick onto list */
	if (!(packed_list = pytdbpack_number('d', val_iter, packed_list)))
		return NULL;

	/* this assumes that the string is the right length; the old code did
	   the same. */
	if (!(val_obj = PyIter_Next(val_iter)))
		return NULL;

	if (!PyString_Check(val_obj)) {
		pytdbpack_bad_type('B', "String", val_obj);
		goto out;
	}
	
	if (PyList_Append(packed_list, val_obj) != -1)
		new_list = packed_list;

  out:
	Py_XDECREF(val_obj);
	return new_list;
}


static PyObject *pytdbpack_bad_type(char ch,
				    const char *expected,
				    PyObject *val_obj)
{
	PyObject *r = PyObject_Repr(val_obj);
	if (!r)
		return NULL;
	PyErr_Format(PyExc_TypeError,
		     "tdbpack: format '%c' requires %s, not %s",
		     ch, expected, PyString_AS_STRING(r));
	Py_DECREF(r);
	return val_obj;
}


/*
  XXX: glib and Samba have quicker macro for doing the endianness conversions,
  but I don't know of one in plain libc, and it's probably not a big deal.  I
  realize this is kind of dumb because we'll almost always be on x86, but
  being safe is important.
*/
static void pack_le_uint32(unsigned long val_long, unsigned char *pbuf)
{
	pbuf[0] =         val_long & 0xff;
	pbuf[1] = (val_long >> 8)  & 0xff;
	pbuf[2] = (val_long >> 16) & 0xff;
	pbuf[3] = (val_long >> 24) & 0xff;
}


#if 0	/* not used */
static void pack_bytes(long len, const char *from,
		       unsigned char **pbuf)
{
	memcpy(*pbuf, from, len);
	(*pbuf) += len;
}
#endif


static PyObject *
pytdbunpack(PyObject *self,
		 PyObject *args)
{
	char *format_str, *packed_str, *ppacked;
	PyObject *val_list = NULL, *ret_tuple = NULL;
	PyObject *rest_string = NULL;
	int format_len, packed_len;
	char last_format = '#';	/* invalid */
	int i;
	
	/* get arguments */
	if (!PyArg_ParseTuple(args, "ss#", &format_str, &packed_str, &packed_len))
		return NULL;

	format_len = strlen(format_str);
	
	/* Allocate list to hold results.  Initially empty, and we append
	   results as we go along. */
	val_list = PyList_New(0);
	if (!val_list)
		goto failed;
	ret_tuple = PyTuple_New(2);
	if (!ret_tuple)
		goto failed;
	
	/* For every object, unpack.  */
	for (ppacked = packed_str, i = 0; i < format_len && format_str[i] != '$'; i++) {
		last_format = format_str[i];
		/* packed_len is reduced in place */
		if (!pytdbunpack_item(format_str[i], &ppacked, &packed_len, val_list))
			goto failed;
	}

	/* If the last character was '$', keep going until out of space */
	if (format_str[i] == '$') {
		if (i == 0) {
			PyErr_Format(PyExc_ValueError,
				     "%s: '$' may not be first character in format",
				     FUNCTION_MACRO);
			return NULL;
		} 
		while (packed_len > 0)
			if (!pytdbunpack_item(last_format, &ppacked, &packed_len, val_list))
				goto failed;
	}
	
	/* save leftovers for next time */
	rest_string = PyString_FromStringAndSize(ppacked, packed_len);
	if (!rest_string)
		goto failed;

	/* return (values, rest) tuple; give up references to them */
	PyTuple_SET_ITEM(ret_tuple, 0, val_list);
	val_list = NULL;
	PyTuple_SET_ITEM(ret_tuple, 1, rest_string);
	val_list = NULL;
	return ret_tuple;

  failed:
	/* handle failure: deallocate anything.  XDECREF forms handle NULL
	   pointers for objects that haven't been allocated yet. */
	Py_XDECREF(val_list);
	Py_XDECREF(ret_tuple);
	Py_XDECREF(rest_string);
	return NULL;
}


static void
pytdbunpack_err_too_short(void)
{
	PyErr_Format(PyExc_IndexError,
		     "%s: data too short for unpack format", FUNCTION_MACRO);
}


static PyObject *
pytdbunpack_uint32(char **pbuf, int *plen)
{
	unsigned long v;
	unsigned char *b;
	
	if (*plen < 4) {
		pytdbunpack_err_too_short();
		return NULL;
	}

	b = *pbuf;
	v = b[0] | b[1]<<8 | b[2]<<16 | b[3]<<24;
	
	(*pbuf) += 4;
	(*plen) -= 4;

	return PyLong_FromUnsignedLong(v);
}


static PyObject *pytdbunpack_int16(char **pbuf, int *plen)
{
	long v;
	unsigned char *b;
	
	if (*plen < 2) {
		pytdbunpack_err_too_short();
		return NULL;
	}

	b = *pbuf;
	v = b[0] | b[1]<<8;
	
	(*pbuf) += 2;
	(*plen) -= 2;

	return PyInt_FromLong(v);
}


static PyObject *
pytdbunpack_string(char **pbuf, int *plen, const char *encoding)
{
	int len;
	char *nul_ptr, *start;

	start = *pbuf;
	
	nul_ptr = memchr(start, '\0', *plen);
	if (!nul_ptr) {
		pytdbunpack_err_too_short();
		return NULL;
	}

	len = nul_ptr - start;

	*pbuf += len + 1;	/* skip \0 */
	*plen -= len + 1;

	return PyString_Decode(start, len, encoding, NULL);
}


static PyObject *
pytdbunpack_buffer(char **pbuf, int *plen, PyObject *val_list)
{
	/* first get 32-bit len */
	long slen;
	unsigned char *b;
	unsigned char *start;
	PyObject *str_obj = NULL, *len_obj = NULL;
	
	if (*plen < 4) {
		pytdbunpack_err_too_short();
		return NULL;
	}
	
	b = *pbuf;
	slen = b[0] | b[1]<<8 | b[2]<<16 | b[3]<<24;

	if (slen < 0) { /* surely you jest */
		PyErr_Format(PyExc_ValueError,
			     "%s: buffer seems to have negative length", FUNCTION_MACRO);
		return NULL;
	}

	(*pbuf) += 4;
	(*plen) -= 4;
	start = *pbuf;

	if (*plen < slen) {
		PyErr_Format(PyExc_IndexError,
			     "%s: not enough data to unpack buffer: "
			     "need %d bytes, have %d", FUNCTION_MACRO,
			     (int) slen, *plen);
		return NULL;
	}

	(*pbuf) += slen;
	(*plen) -= slen;

	if (!(len_obj = PyInt_FromLong(slen)))
		goto failed;

	if (PyList_Append(val_list, len_obj) == -1)
		goto failed;
	
	if (!(str_obj = PyString_FromStringAndSize(start, slen)))
		goto failed;
	
	if (PyList_Append(val_list, str_obj) == -1)
		goto failed;
	
	Py_DECREF(len_obj);
	Py_DECREF(str_obj);
	
	return val_list;

  failed:
	Py_XDECREF(len_obj);	/* handles NULL */
	Py_XDECREF(str_obj);
	return NULL;
}


/* Unpack a single field from packed data, according to format character CH.
   Remaining data is at *PBUF, of *PLEN.

   *PBUF is advanced, and *PLEN reduced to reflect the amount of data that has
   been consumed.

   Returns a reference to None, or NULL for failure.
*/
static PyObject *pytdbunpack_item(char ch,
				  char **pbuf,
				  int *plen,
				  PyObject *val_list)
{
	PyObject *unpacked;
	
	if (ch == 'w') {	/* 16-bit int */
		unpacked = pytdbunpack_int16(pbuf, plen);
	}
	else if (ch == 'd' || ch == 'p') { /* 32-bit int */
		/* pointers can just come through as integers */
		unpacked = pytdbunpack_uint32(pbuf, plen);
	}
	else if (ch == 'f' || ch == 'P') { /* nul-term string  */
		unpacked = pytdbunpack_string(pbuf, plen, pytdb_unix_encoding);
	}
	else if (ch == 'B') { /* length, buffer */
		return pytdbunpack_buffer(pbuf, plen, val_list);
	}
	else {
		PyErr_Format(PyExc_ValueError,
			     "%s: format character '%c' is not supported", 
                             FUNCTION_MACRO, ch);
		
		return NULL;
	}

	/* otherwise OK */
	if (!unpacked)
		return NULL;

	if (PyList_Append(val_list, unpacked) == -1)
		val_list = NULL;

	/* PyList_Append takes a new reference to the inserted object.
	   Therefore, we no longer need the original reference. */
	Py_DECREF(unpacked);
	
	return val_list;
}






static PyMethodDef pytdbpack_methods[] = {
	{ "pack", pytdbpack, METH_VARARGS, (char *) pytdbpack_doc },
	{ "unpack", pytdbunpack, METH_VARARGS, (char *) pytdbunpack_doc },
};

DL_EXPORT(void)
inittdbpack(void)
{
	Py_InitModule3("tdbpack", pytdbpack_methods,
		       (char *) pytdbpack_docstring);
}