From: Anton Khirnov <anton@khirnov.net>
Date: Mon, 15 Jun 2020 20:58:49 +0000 (+0200)
Subject: python/notmuch2: do not destroy messages owned by a query
X-Git-Tag: archive/debian/0.30_rc2-1~6
X-Git-Url: https://git.cworth.org/git?a=commitdiff_plain;h=131757907907380213b32934d9e73cec942ace43;hp=131757907907380213b32934d9e73cec942ace43;p=notmuch

python/notmuch2: do not destroy messages owned by a query

Any messages retrieved from a query - either directly via
search_messages() or indirectly via thread objects - are owned by that
query. Retrieving the same message (i.e. corresponding to the same
message ID / database object) several times will always yield the same
C object.

The caller is allowed to destroy message objects owned by a query before
the query itself - which can save memory for long-lived queries.
However, that message must then never be retrieved again from that
query.

The python-notmuch2 bindings will currently destroy every message object
in Message._destroy(), which will lead to an invalid free if the same
message is then retrieved again. E.g. the following python program leads
to libtalloc abort()ing:

import notmuch2
db   = notmuch2.Database(mode = notmuch2.Database.MODE.READ_ONLY)
t    = next(db.threads('*'))
msgs = list(zip(t.toplevel(), t.toplevel()))
msgs = list(zip(t.toplevel(), t.toplevel()))

Fix this issue by creating a subclass of Message, which is used for
"standalone" message which have to be freed by the caller. Message class
is then used only for messages descended from a query, which do not need
to be freed by the caller.
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