New submission from STINNER Victor <victor.stin...@haypocalc.com>:
Steps 1 and 3 of PyUnicode_FromFormatV() doesn't handle the format string "%%"
correctly. The loop responsible to skip the precision moves outside the format
string, and the function will then read uninitialized memory. The loop:
while (*++f && *f != '%' && !Py_ISALPHA((unsigned)*f))
;
This is another issue:
for (f = format; *f; f++) {
if (*f == '%') {
if (*(f+1)=='%')
continue;
...
continue only skips the first %: with "%%", the second % will be interpreted
(and not escaped).
Attached patch fixes the issue, but I don't feal confortable with this ugly
function, and I would appreciate a review :-) The patch adds unit tests.
I found the bug when trying to add new tests before trying to implement "%zi"
format. I was first surprised that "%zi" (and %li and %lli) is not supported,
but now I am surprised because I found bugs :-)
----------
components: Interpreter Core, Unicode
files: pyunicode_fromformatv.patch
keywords: patch
messages: 125387
nosy: amaury.forgeotdarc, haypo
priority: normal
severity: normal
status: open
title: PyUnicode_FromFormatV() bugs with "%" and "%%" format strings
versions: Python 2.6, Python 2.7, Python 3.1, Python 3.2
Added file: http://bugs.python.org/file20262/pyunicode_fromformatv.patch
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue10829>
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