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/Doc/library/zlib.rst b/Doc/library/zlib.rst
index 94e429e..b522fe6 100644
--- a/Doc/library/zlib.rst
+++ b/Doc/library/zlib.rst
@@ -42,6 +42,12 @@
the algorithm is designed for use as a checksum algorithm, it is not suitable
for use as a general hash algorithm.
+ This function always returns an integer object.
+
+.. versionchanged:: 2.6
+ For consistent cross-platform behavior we always return a signed integer.
+ ie: Results in the (2**31)...(2**32-1) range will be negative.
+
.. function:: compress(string[, level])
@@ -74,6 +80,12 @@
the algorithm is designed for use as a checksum algorithm, it is not suitable
for use as a general hash algorithm.
+ This function always returns an integer object.
+
+.. versionchanged:: 2.6
+ For consistent cross-platform behavior we always return a signed integer.
+ ie: Results in the (2**31)...(2**32-1) range will be negative.
+
.. function:: decompress(string[, wbits[, bufsize]])
diff --git a/Lib/test/test_zlib.py b/Lib/test/test_zlib.py
index 13926e1..7c7ef26 100644
--- a/Lib/test/test_zlib.py
+++ b/Lib/test/test_zlib.py
@@ -38,6 +38,15 @@
self.assertEqual(zlib.crc32("penguin"), zlib.crc32("penguin", 0))
self.assertEqual(zlib.adler32("penguin"),zlib.adler32("penguin",1))
+ def test_abcdefghijklmnop(self):
+ """test issue1202 compliance: signed crc32, adler32 in 2.x"""
+ foo = 'abcdefghijklmnop'
+ # explicitly test signed behavior
+ self.assertEqual(zlib.crc32(foo), -1808088941)
+ self.assertEqual(zlib.crc32('spam'), 1138425661)
+ self.assertEqual(zlib.adler32(foo+foo), -721416943)
+ self.assertEqual(zlib.adler32('spam'), 72286642)
+
class ExceptionTestCase(unittest.TestCase):
diff --git a/Misc/NEWS b/Misc/NEWS
index 47f8df1..1963ad5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -27,6 +27,10 @@
Library
-------
+- Issue #1202: zlib.crc32 and zlib.adler32 no longer return different values
+ on 32-bit vs. 64-bit python interpreters. Both were correct, but they now
+ both return a signed integer object for consistency.
+
- Issue #1158: add %f format (fractions of a second represented as
microseconds) to datetime objects. Understood by both strptime and
strftime.
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);
}