Force zlib.crc32 and zlib.adler32 to return a signed integer on all platforms
regardless of the native sizeof(long) used in the integer object.
This somewhat odd behavior of returning a signed is maintained in 2.x for
compatibility reasons of always returning an integer rather than a long object.
Fixes Issue1202 for Python 2.6
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index ef00cca..384399d 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -884,37 +884,46 @@
"adler32(string[, start]) -- Compute an Adler-32 checksum of string.\n"
"\n"
"An optional starting value can be specified. The returned checksum is\n"
-"an integer.");
+"a signed integer.");
static PyObject *
PyZlib_adler32(PyObject *self, PyObject *args)
{
uLong adler32val = adler32(0L, Z_NULL, 0);
Byte *buf;
- int len;
+ int len, signed_val;
if (!PyArg_ParseTuple(args, "s#|k:adler32", &buf, &len, &adler32val))
return NULL;
- adler32val = adler32(adler32val, buf, len);
- return PyInt_FromLong(adler32val);
+ /* In Python 2.x we return a signed integer regardless of native platform
+ * long size (the 32bit unsigned long is treated as 32-bit signed and sign
+ * extended into a 64-bit long inside the integer object). 3.0 does the
+ * right thing and returns unsigned. http://bugs.python.org/issue1202 */
+ signed_val = adler32(adler32val, buf, len);
+ return PyInt_FromLong(signed_val);
}
PyDoc_STRVAR(crc32__doc__,
"crc32(string[, start]) -- Compute a CRC-32 checksum of string.\n"
"\n"
"An optional starting value can be specified. The returned checksum is\n"
-"an integer.");
+"a signed integer.");
static PyObject *
PyZlib_crc32(PyObject *self, PyObject *args)
{
uLong crc32val = crc32(0L, Z_NULL, 0);
Byte *buf;
- int len;
+ int len, signed_val;
+
if (!PyArg_ParseTuple(args, "s#|k:crc32", &buf, &len, &crc32val))
return NULL;
- crc32val = crc32(crc32val, buf, len);
- return PyInt_FromLong(crc32val);
+ /* In Python 2.x we return a signed integer regardless of native platform
+ * long size (the 32bit unsigned long is treated as 32-bit signed and sign
+ * extended into a 64-bit long inside the integer object). 3.0 does the
+ * right thing and returns unsigned. http://bugs.python.org/issue1202 */
+ signed_val = crc32(crc32val, buf, len);
+ return PyInt_FromLong(signed_val);
}