qcrypto/core: add generic infrastructure for crypto options amendment

This will be used first to implement luks keyslot management.

block_crypto_amend_opts_init will be used to convert
qemu-img cmdline to QCryptoBlockAmendOptions

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200608094030.670121-2-mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
diff --git a/block/crypto.c b/block/crypto.c
index 973b57b..dcf8b42 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -202,6 +202,23 @@
     return ret;
 }
 
+QCryptoBlockAmendOptions *
+block_crypto_amend_opts_init(QDict *opts, Error **errp)
+{
+    Visitor *v;
+    QCryptoBlockAmendOptions *ret;
+
+    v = qobject_input_visitor_new_flat_confused(opts, errp);
+    if (!v) {
+        return NULL;
+    }
+
+    visit_type_QCryptoBlockAmendOptions(v, NULL, &ret, errp);
+
+    visit_free(v);
+    return ret;
+}
+
 
 static int block_crypto_open_generic(QCryptoBlockFormat format,
                                      QemuOptsList *opts_spec,
diff --git a/block/crypto.h b/block/crypto.h
index b935695..06e044c 100644
--- a/block/crypto.h
+++ b/block/crypto.h
@@ -91,6 +91,9 @@
 QCryptoBlockCreateOptions *
 block_crypto_create_opts_init(QDict *opts, Error **errp);
 
+QCryptoBlockAmendOptions *
+block_crypto_amend_opts_init(QDict *opts, Error **errp);
+
 QCryptoBlockOpenOptions *
 block_crypto_open_opts_init(QDict *opts, Error **errp);