From f5cdacfa91067594de16028e057eace3e8c30040 Mon Sep 17 00:00:00 2001 From: "Michael W. Hudson" Date: Wed, 25 Sep 2002 10:22:50 +0000 Subject: [PATCH] backport tim_one's checkin of revision 2.35 of binascii.c Fix for SF bug #576327: zipfile when sizeof(long) == 8 binascii_crc32(): Make this return a signed 4-byte result across platforms. The other way to make this platform-independent would be to make it return an unsigned unbounded int, but the evidence suggests other code out there treats it like a signed 4-byte int (e.g., existing code writing the result with struct.pack "l" format). Bugfix candidate. --- Modules/binascii.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/Modules/binascii.c b/Modules/binascii.c index 70d60f024886..9d710f5cb158 100644 --- a/Modules/binascii.c +++ b/Modules/binascii.c @@ -861,6 +861,7 @@ binascii_crc32(PyObject *self, PyObject *args) unsigned char *bin_data; unsigned long crc = 0UL; /* initial value of CRC */ int len; + long result; if ( !PyArg_ParseTuple(args, "s#|l:crc32", &bin_data, &len, &crc) ) return NULL; @@ -869,7 +870,16 @@ binascii_crc32(PyObject *self, PyObject *args) while(len--) crc = crc_32_tab[(crc ^ *bin_data++) & 0xffUL] ^ (crc >> 8); /* Note: (crc >> 8) MUST zero fill on left */ - return Py_BuildValue("l", crc ^ 0xFFFFFFFFUL); + + result = (long)(crc ^ 0xFFFFFFFFUL); + /* If long is > 32 bits, extend the sign bit. This is one way to + * ensure the result is the same across platforms. The other way + * would be to return an unbounded long, but the evidence suggests + * that lots of code outside this treats the result as if it were + * a signed 4-byte integer. + */ + result |= -(result & (1L << 31)); + return PyInt_FromLong(result); } -- 2.47.3