Starting with sq version 0.28 the verify --signer-cert and
sign --signer-key options got replaced with --signer-file.

This maps the requirements from dpkg itself. Although we do not
currently abort in case the compiler used does not support C99.

The pkg-config project upstream has been stagnant for a while and has
issues with its implementation. Switch to the more lively, even though
in maintenance mode, pkgconf project.

This was previously supported because we were always falling back to
match, which was not truly honoring the declared policy.

Add explicit support for multiple subkeys.

Closes: #1059150
Based-on-patch-by: Steve McIntyre <steve@einval.com>

Instead of hardcoding it globally, let's make it possible to set a
different key per test.

This module now only contains a debugging logging function, rename to
make its purpose more clear.

Changelog: internal

Require libdpkg (>= 1.22.0) so that we can use this newly exported
function instead of the embedded copy which can be removed now.

This function will get exported by libdpkg >= 1.22.0. We rename it to
use the same name so that we can then switch the version from libdpkg
and drop our current embedded implementation.

Changelog: internal

The field getters already return an allocated duplicate string, so there
is no need to duplicate it again, which will just cause a memory leak to
happen instead.

Warned-by: coverity
Changelog: internal

If we found a fingerprint, but then that didn't match it or a subsequent
uid, then we could end up leaking fpr.

Warned-by: coverity
Changelog: internal

Split the get-version file into its own stanza, so that it is clear the
earlier year comes from an imported script before the project adoption.

The support has now been added to dpkg 1.21.18.

The libdpkg library is not provided as a shared dynamic library yet,
and we need to explicitly link against any of its directly linked
libraries. Use PKG_CHECK_MODULES_STATIC instead of PKG_CHECK_MODULES.

This is particularly relevant now that libdpkg has grown a dependency
on libmd.

The loop uses this variable on subsequent lines when matched to return
the fingerprint found, so we need to widen its scope. In addition we
need to initialize it to NULL, even though the code takes care of not
using ret when it is NULL, and only set ret to fpr, on the specific
state.

Fixes: commit 29f80390
Warned-by: gcc
Changelog: silent

Fixes: commit 14e70de6
Warned-by: gcc
Changelog: silent

Fixes: commit 3600ebb6
Changelog: silent

This makes debugging more helpful.

The description for the subproc_reap() did not match the function this
code is now in. Give it a more descriptive text.

Changelog: internal

This makes the values easier to identify as pertaining to this member,
through explicit typing.

Changelog: internal

This function does not take a match type, instead it takes a match name.
Rename the argument to avoid confusion.

Changelog: internal

We should check whether the origin ID can be found in the keyring, as
that is the fingerprint/keyID for the signature that selected the
current policy.

It's not essential, as the actual signature verification will be the
final decision point, but it means we might be able to discard this
policy as invalid otherwise, and use another one instead.

This will make it possible to specify arbitrary strings, instead of
having to construct a match struct to be able to call the function.

Changelog: internal