After a brief conversation and code review with TP, adding two very
commonly used functions to convert an arbitrary binary string into a hexadecimal digit representation and back again. These are often (and often differently) implemented in Python. Best to have one common fast implementation. Specifically, binascii_hexlify(): a.k.a. b2a_hex() to return the hex representation of binary data. binascii_unhexlify(): a.k.a. a2b_hex() to do the inverse conversion (hex digits to binary data). The argument must have an even length, and must contain only hex digits, otherwise a TypeError is raised.
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Barry Warsaw
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57b808d21a
commit
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@ -874,30 +874,134 @@ binascii_crc32(PyObject *self, PyObject *args)
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return Py_BuildValue("l", crc ^ 0xFFFFFFFFUL);
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}
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static PyObject *
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binascii_hexlify(PyObject *self, PyObject *args)
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{
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char* argbuf;
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int arglen;
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PyObject *retval;
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char* retbuf;
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int i, j;
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if (!PyArg_ParseTuple(args, "t#:b2a_hex", &argbuf, &arglen))
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return NULL;
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retval = PyString_FromStringAndSize(NULL, arglen*2);
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if (!retval)
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return NULL;
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retbuf = PyString_AsString(retval);
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if (!retbuf)
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goto finally;
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/* make hex version of string, taken from shamodule.c */
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for (i=j=0; i < arglen; i++) {
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char c;
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c = (argbuf[i] >> 4) & 0xf;
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c = (c>9) ? c+'a'-10 : c + '0';
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retbuf[j++] = c;
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c = argbuf[i] & 0xf;
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c = (c>9) ? c+'a'-10 : c + '0';
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retbuf[j++] = c;
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}
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return retval;
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finally:
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Py_DECREF(retval);
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return NULL;
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}
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static char doc_hexlify[] =
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"b2a_hex(data) -> s; Hexadecimal representation of binary data.\n\
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\n\
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This function is also available as \"hexlify()\".";
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static int
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to_int(char c)
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{
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if (isdigit(c))
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return c - '0';
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else {
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if (isupper(c))
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c = tolower(c);
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if (c >= 'a' && c <= 'f')
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return c - 'a' + 10;
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}
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return -1;
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}
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static PyObject *
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binascii_unhexlify(PyObject *self, PyObject *args)
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{
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char* argbuf;
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int arglen;
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PyObject *retval;
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char* retbuf;
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int i, j;
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if (!PyArg_ParseTuple(args, "s#:a2b_hex", &argbuf, &arglen))
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return NULL;
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/* XXX What should we do about odd-lengthed strings? Should we add
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* an implicit leading zero, or a trailing zero? For now, raise an
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* exception.
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*/
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if (arglen % 2) {
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PyErr_SetString(PyExc_TypeError, "odd lengthed string");
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return NULL;
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}
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retval = PyString_FromStringAndSize(NULL, (arglen/2));
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if (!retval)
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return NULL;
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retbuf = PyString_AsString(retval);
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if (!retbuf)
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goto finally;
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for (i=j=0; i < arglen; i += 2) {
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int top = to_int(Py_CHARMASK(argbuf[i]));
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int bot = to_int(Py_CHARMASK(argbuf[i+1]));
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if (top == -1 || bot == -1) {
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PyErr_SetString(PyExc_TypeError,
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"non-hexadecimal digit found");
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goto finally;
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}
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retbuf[j++] = (top << 4) + bot;
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}
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return retval;
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finally:
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Py_DECREF(retval);
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return NULL;
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}
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static char doc_unhexlify[] =
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"a2b_hex(hexstr) -> s; Binary data of hexadecimal representation.\n\
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\n\
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hexstr must contain an even number of hex digits (upper or lower case).\n\
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This function is also available as \"unhexlify()\"";
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/* List of functions defined in the module */
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static struct PyMethodDef binascii_module_methods[] = {
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{"a2b_uu", binascii_a2b_uu,
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METH_VARARGS, doc_a2b_uu},
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{"b2a_uu", binascii_b2a_uu,
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METH_VARARGS, doc_b2a_uu},
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{"a2b_base64", binascii_a2b_base64,
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METH_VARARGS,
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doc_a2b_base64},
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{"b2a_base64", binascii_b2a_base64,
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METH_VARARGS, doc_b2a_base64},
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{"a2b_hqx", binascii_a2b_hqx,
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METH_VARARGS, doc_a2b_hqx},
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{"b2a_hqx", binascii_b2a_hqx,
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METH_VARARGS, doc_b2a_hqx},
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{"rlecode_hqx", binascii_rlecode_hqx,
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METH_VARARGS, doc_rlecode_hqx},
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{"rledecode_hqx", binascii_rledecode_hqx,
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METH_VARARGS, doc_rledecode_hqx},
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{"crc_hqx", binascii_crc_hqx,
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METH_VARARGS, doc_crc_hqx},
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{"crc32", binascii_crc32,
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METH_VARARGS, doc_crc32},
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{"a2b_uu", binascii_a2b_uu, METH_VARARGS, doc_a2b_uu},
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{"b2a_uu", binascii_b2a_uu, METH_VARARGS, doc_b2a_uu},
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{"a2b_base64", binascii_a2b_base64, METH_VARARGS, doc_a2b_base64},
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{"b2a_base64", binascii_b2a_base64, METH_VARARGS, doc_b2a_base64},
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{"a2b_hqx", binascii_a2b_hqx, METH_VARARGS, doc_a2b_hqx},
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{"b2a_hqx", binascii_b2a_hqx, METH_VARARGS, doc_b2a_hqx},
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{"b2a_hex", binascii_hexlify, METH_VARARGS, doc_hexlify},
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{"a2b_hex", binascii_unhexlify, METH_VARARGS, doc_unhexlify},
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{"hexlify", binascii_hexlify, METH_VARARGS, doc_hexlify},
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{"unhexlify", binascii_unhexlify, METH_VARARGS, doc_unhexlify},
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{"rlecode_hqx", binascii_rlecode_hqx, METH_VARARGS, doc_rlecode_hqx},
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{"rledecode_hqx", binascii_rledecode_hqx, METH_VARARGS,
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doc_rledecode_hqx},
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{"crc_hqx", binascii_crc_hqx, METH_VARARGS, doc_crc_hqx},
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{"crc32", binascii_crc32, METH_VARARGS, doc_crc32},
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{NULL, NULL} /* sentinel */
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};
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