From 037b3ee44e7de00b4653d73d4808c0f679a909a7 Mon Sep 17 00:00:00 2001
From: Tim Peters <tim.peters@gmail.com>
Date: Sat, 21 Aug 2004 06:55:43 +0000
Subject: Patch 1012740: cStringIO's truncate doesn't
truncate() left the stream position unchanged, which meant the
"truncated" data didn't go away:
>>> io.write('abc')
>>> io.truncate(0)
>>> io.write('xyz')
>>> io.getvalue()
'abcxyz'
Patch by Dima Dorfman.
---
Lib/test/test_StringIO.py | 3 ++-
Misc/NEWS | 7 ++++++-
Modules/cStringIO.c | 1 +
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/Lib/test/test_StringIO.py b/Lib/test/test_StringIO.py
index c318eaa..6842c5e 100644
--- a/Lib/test/test_StringIO.py
+++ b/Lib/test/test_StringIO.py
@@ -49,9 +49,10 @@ class TestGenericStringIO(unittest.TestCase):
f.seek(10)
f.truncate()
eq(f.getvalue(), 'abcdefghij')
- f.seek(0)
f.truncate(5)
eq(f.getvalue(), 'abcde')
+ f.write('xyz')
+ eq(f.getvalue(), 'abcdexyz')
f.close()
self.assertRaises(ValueError, f.write, 'frobnitz')
diff --git a/Misc/NEWS b/Misc/NEWS
index a8aee9c..6b1dcff 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -41,6 +41,11 @@ Core and builtins
Extension modules
-----------------
+- Patch 1012740: truncate() on a writeable cStringIO now resets the
+ position to the end of the stream. This is consistent with the original
+ StringIO module and avoids inadvertently resurrecting data that was
+ supposed to have been truncated away.
+
- Added socket.socketpair().
Library
@@ -59,7 +64,7 @@ Library
- A new function tkFont.nametofont was added to return an existing
font. The Font class constructor now has an additional exists argument
which, if True, requests to return/configure an existing font, rather
- than creating a new one.
+ than creating a new one.
- Updated the decimal package's min() and max() methods to match the
latest revision of the General Decimal Arithmetic Specification.
diff --git a/Modules/cStringIO.c b/Modules/cStringIO.c
index 7e75879..b7333fd 100644
--- a/Modules/cStringIO.c
+++ b/Modules/cStringIO.c
@@ -289,6 +289,7 @@ IO_truncate(IOobject *self, PyObject *args) {
if (pos < 0) pos = self->pos;
if (self->string_size > pos) self->string_size = pos;
+ self->pos = self->string_size;
Py_INCREF(Py_None);
return Py_None;
--
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