[liblouis-liblouisxml] Re: Crash in Python hyphenation
- From: Christian Egli <christian.egli@xxxxxx>
- To: James Teh <jamie@xxxxxxxxxxxx>
- Date: Thu, 07 Jun 2012 09:23:42 +0200
James Teh <jamie@xxxxxxxxxxxx> writes:
> I think this is really a bug in liblouis, though. The documentation
> says the output buffer must be of size inlen, so it shouldn't write
> past inlen.
I looked at the source code of lou_hyphenate and couldn't find the
source of the problem. I looked at liblouisxml and the java bindings in
liblouisutdml to see how they deal with the issue. liblouisxml just
allocates a big static buffer for the hyphens array, so it is probably
not directly affected. The java bindings in liblouisutdml might also
suffer from the same problem that the Python bindings have.
So, if noone is fixing the code in lou_hyphenate I suggest that we put
the following workaround in the Python bindings:
Index: python/louis/__init__.py.in
===================================================================
--- python/louis/__init__.py.in (revision 675)
+++ python/louis/__init__.py.in (working copy)
@@ -262,7 +262,10 @@
tablesString = _createTablesString(tableList)
inbuf = createStr(inbuf)
inlen = c_int(len(inbuf))
- hyphen_string = create_string_buffer(inlen.value)
+ # lou_hyphenate has a bug in that it writes past the end of the
+ # hyphens array. To work around this we allocate a hyphen_string
+ # which is slightly bigger than it really ought to be
+ hyphen_string = create_string_buffer(inlen.value + sizeof(c_wchar))
if not liblouis.lou_hyphenate(tablesString, inbuf, inlen, hyphen_string,
mode):
raise RuntimeError("Can't hyphenate tables %s, inbuf %s, mode %d"
%(tablesString, inbuf, mode))
return hyphen_string.value.decode("ASCII")
--
Christian Egli
Swiss Library for the Blind, Visually Impaired and Print Disabled
Grubenstrasse 12, CH-8045 Zürich, Switzerland
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