The code filled with #ifdef GMIME_ATLEAST_26 is difficult to
read. Abstract gpg context creation into a function, with separate
implementations for GMime 2.4 and 2.6, to clarify the code.
There should be no functional changes.
For decryption, we expect there to be a functioning gpg-agent, and we
want gpg to talk to it for any needed credentials. There's a gmime
function to declare that: g_mime_gpg_context_set_use_agent() [1], [2].
Start using it.
I had gpg-agent running, but gpg "use-agent" configuration option
disabled. This resulted in an error message from 'notmuch show':
Failed to decrypt part: Canceled.
and json had this:
"encstatus" : [ { "status" : "bad" } ]
One could argue the "use-agent" option should be enabled, but I'd like
to use the agent only as a last resort. I think that's irrelevant
though. There's a gmime function to declare what we expect, so we
should use it. Conveniently it also fixes the problem in a user
friendly way.
[1] http://git.gnome.org/browse/gmime/commit/?id=ed985397843a9da3745a8b5de3d1d652acd24724
[2] https://bugzilla.gnome.org/show_bug.cgi?id=651826
This new structure, notmuch_crypto_t, keeps all relevant crypto
contexts and parameters together, and will make it easier to pass the
stuff around and clean it up. The name of the crypto context inside
this new struct will change, to reflect that it is actually a GPG
context, which is a sub type of Crypto context. There are other types
of Crypto contexts (Pkcs7 in particular, which we hope to support) so
we want to be clear.
The new crypto.c contains functions to return the proper context from
the struct for a given protocol (and initialize it if needed), and to
cleanup a struct by releasing the crypto contexts.
