Marius Gedminas authored Oct 23, 2015 and Carlos Garnacho committed Oct 23, 2015

libunistring uses UTF-8 strings without a trailing NUL byte.  We're
passing such strings to tracker_parser_unaccent_nfkd_string() from
function_sparql_unaccent() in the sqlite interface.  If the string has
no accented characters, writing a NUL byte at the end will step out of
bounds.  This causes memory corruption and crashes.

The other caller of tracker_parser_unaccent_nfkd_string() is
process_word_utf8(), and it looks like it wants a trailing NUL, so let's
add it there.

There are no more callers of the libunistring version of
tracker_parser_unaccent_nfkd_string().

(For extra confusion, the libicu version of
tracker_parser_unaccent_nfkd_string() deals with U+0000-terminated
UTF-16 strings.)

Should fix https://bugzilla.gnome.org/show_bug.cgi?id=746195