libnotmuch_util.a is supposed to be usable from the library and the
CLI, but much the library is compiled as C++. Add in appropriate
wrapping to prevent symbol mangling. These wrappers already existed in
string-util.h; it seems better to be consistent.
When i'm trying to understand a message signature, i care that i know
who it came from (the "validity" of the identity associated with the
key), *not* whether i'm willing to accept the keyholder's other
identity assertions (the "trust" associated with the certificate).
We've been reporting User ID information based on the "trust"
associated with the certificate, because GMime didn't clearly expose
the validity of the User IDs.
This change relies on fixes made in GMime 3.0.3 and later which
include https://github.com/jstedfast/gmime/pull/18.
In practice, we're going to see this function invoked differently
depending on which gmime we build against. The compatibility layer
forces our code into the lowest-common-denominator -- unable to make
use of new features even when built against a newer version.
Dropping the compatibility layer paves the way for clearer use of
features from GMime 3.0 in future commits.
"typedef GMimeAddressType GMimeRecipientType" is already present
further down in the compatibility wrapper (with other typedefs). We
don't need it twice.
When compiling as C code (instead of C++) against gmime 3.0, gcc gives
errors like the following:
error: invalid conversion from ‘int’ to ‘GMimeDecryptFlags’ [-fpermissive]
so use explicit *_NONE values instead.
The "key_id" field seems to used for userid in gmime-3.0, while the
keyid is dropped in the fingerprint field if the full fingerprint is
not available.
It turns out that our use of GMimeStreamPipe has only succeeded
because gmime has been ignoring some seek failures; this will no
longer be the case in gmime 3.0, so we use a GMimeStreamPipe, which
does not assume seekability, wrapped in a buffering stream.
