From: Thomas Heller <theller@ctypes.org>
Date: Tue, 8 Aug 2006 17:42:30 +0000 (+0000)
Subject: memcmp() can return values other than -1, 0, and +1 but tp_compare
X-Git-Tag: v2.4.4c1~129
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f6f89e602c29b2a0d50ccde6bd8cb36e8c4621d4;p=thirdparty%2FPython%2Fcpython.git

memcmp() can return values other than -1, 0, and +1 but tp_compare
must not.
---

diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index 4abc7caafb34..38cf2189081c 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -229,6 +229,7 @@ print 'Buffers'
 try: buffer('asdf', -1)
 except ValueError: pass
 else: raise TestFailed, "buffer('asdf', -1) should raise ValueError"
+cmp(buffer("abc"), buffer("def")) # used to raise a warning: tp_compare didn't return -1, 0, or 1
 
 try: buffer(None)
 except TypeError: pass
diff --git a/Misc/NEWS b/Misc/NEWS
index c15925720c5e..ad1bb0702c76 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@ What's New in Python 2.4.4c1?
 Core and builtins
 -----------------
 
+- Bug #1536786: buffer comparison could emit a RuntimeWarning.
+
 - Bug #1535165: fixed a segfault in input() and raw_input() when
   sys.stdin is closed.
 
diff --git a/Objects/bufferobject.c b/Objects/bufferobject.c
index da8d9fc6a257..a677d0cda348 100644
--- a/Objects/bufferobject.c
+++ b/Objects/bufferobject.c
@@ -230,7 +230,7 @@ buffer_compare(PyBufferObject *self, PyBufferObject *other)
 	if (min_len > 0) {
 		cmp = memcmp(p1, p2, min_len);
 		if (cmp != 0)
-			return cmp;
+			return cmp < 0 ? -1 : 1;
 	}
 	return (len_self < len_other) ? -1 : (len_self > len_other) ? 1 : 0;
 }