repo: Add functions for verifying any data in repository

This can be useful for validating the 3rd party data that is put in
the extensions directory and is signed with the same keys as commits
or the summary file.

Closes: #310
Approved by: cgwalters

src/libostree/libostree.sym

@@ -342,5 +342,6 @@ LIBOSTREE_2016.6 {
 global:
         ostree_gpg_verify_result_require_valid_signature;
         ostree_raw_file_to_archive_z2_stream;
+        ostree_repo_gpg_verify_data;
         ostree_repo_remote_fetch_summary_with_options;
 } LIBOSTREE_2016.5;

src/libostree/ostree-repo.c

@@ -4893,6 +4893,49 @@ ostree_repo_verify_commit_ext (OstreeRepo    *self,
                                               error);
 }
 
+/**
+ * ostree_repo_gpg_verify_data:
+ * @self: Repository
+ * @remote_name: (nullable): Name of remote
+ * @data: Data as a #GBytes
+ * @signatures: Signatures as a #GBytes
+ * @keyringdir: (nullable): Path to directory GPG keyrings; overrides built-in default if given
+ * @extra_keyring: (nullable): Path to additional keyring file (not a directory)
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Verify @signatures for @data using GPG keys in the keyring for
+ * @remote_name, and return an #OstreeGpgVerifyResult.
+ *
+ * The @remote_name parameter can be %NULL. In that case it will do
+ * the verifications using GPG keys in the keyrings of all remotes.
+ *
+ * Returns: (transfer full): an #OstreeGpgVerifyResult, or %NULL on error
+ */
+OstreeGpgVerifyResult *
+ostree_repo_gpg_verify_data (OstreeRepo    *self,
+                             const gchar   *remote_name,
+                             GBytes        *data,
+                             GBytes        *signatures,
+                             GFile         *keyringdir,
+                             GFile         *extra_keyring,
+                             GCancellable  *cancellable,
+                             GError       **error)
+{
+  g_return_val_if_fail (OSTREE_IS_REPO (self), NULL);
+  g_return_val_if_fail (data != NULL, NULL);
+  g_return_val_if_fail (signatures != NULL, NULL);
+
+  return _ostree_repo_gpg_verify_data_internal (self,
+                                                (remote_name != NULL) ? remote_name : OSTREE_ALL_REMOTES,
+                                                data,
+                                                signatures,
+                                                keyringdir,
+                                                extra_keyring,
+                                                cancellable,
+                                                error);
+}
+
 /**
  * ostree_repo_verify_summary:
  * @self: Repo

src/libostree/ostree-repo.h

@@ -1030,6 +1030,16 @@ OstreeGpgVerifyResult * ostree_repo_verify_commit_ext (OstreeRepo    *self,
                                                        GCancellable  *cancellable,
                                                        GError       **error);
 
+_OSTREE_PUBLIC
+OstreeGpgVerifyResult * ostree_repo_gpg_verify_data (OstreeRepo    *self,
+                                                     const gchar   *remote_name,
+                                                     GBytes        *data,
+                                                     GBytes        *signatures,
+                                                     GFile         *keyringdir,
+                                                     GFile         *extra_keyring,
+                                                     GCancellable  *cancellable,
+                                                     GError       **error);
+
 _OSTREE_PUBLIC
 OstreeGpgVerifyResult * ostree_repo_verify_summary (OstreeRepo    *self,
                                                     const char    *remote_name,