signing: Change API to create instances directly

This cleans up the verification code; it was weird how
we'd get the list of known names and then try to create
an instance from it (and throw an error if that failed, which
couldn't happen).

apidoc/ostree-sections.txt

@@ -709,7 +709,7 @@ ostree_kernel_args_to_string
 <SECTION>
 <FILE>ostree-sign</FILE>
 OstreeSign
-ostree_sign_list_names
+ostree_sign_get_all
 ostree_sign_commit
 ostree_sign_commit_verify
 ostree_sign_data

src/libostree/libostree-devel.sym

@@ -23,7 +23,7 @@ global:
   ostree_repo_commit_modifier_set_sepolicy_from_commit;
   someostree_symbol_deleteme;
   ostree_sign_get_type;
-  ostree_sign_list_names;
+  ostree_sign_get_all;
   ostree_sign_commit;
   ostree_sign_commit_verify;
   ostree_sign_data;

src/libostree/ostree-repo-pull-verify.c

@@ -142,6 +142,9 @@ _signapi_load_public_keys (OstreeSign *sign,
   return TRUE;
 }
 
+/* Iterate over all known signing types, and check if the commit is signed
+ * by at least one.
+ */
 gboolean
 _sign_verify_for_remote (OstreeRepo *repo,
                           const gchar *remote_name,
@@ -149,32 +152,18 @@ _sign_verify_for_remote (OstreeRepo *repo,
                           GVariant *metadata,
                           GError **error)
 {
-  /* list all signature types in detached metadata and check if signed by any? */
-  g_auto (GStrv) names = ostree_sign_list_names();
   guint n_invalid_signatures = 0;
-  guint n_unknown_signatures = 0;
   g_autoptr (GError) last_sig_error = NULL;
   gboolean found_sig = FALSE;
 
-  for (char **iter=names; iter && *iter; iter++)
+  g_autoptr(GPtrArray) signers = ostree_sign_get_all ();
+  for (guint i = 0; i < signers->len; i++)
     {
-      g_autoptr (OstreeSign) sign = NULL;
-      g_autoptr (GVariant) signatures = NULL;
-      const gchar *signature_key = NULL;
-      GVariantType *signature_format = NULL;
-
-      if ((sign = ostree_sign_get_by_name (*iter, NULL)) == NULL)
-        {
-          n_unknown_signatures++;
-          continue;
-        }
-
-      signature_key = ostree_sign_metadata_key (sign);
-      signature_format = (GVariantType *) ostree_sign_metadata_format (sign);
-
-      signatures = g_variant_lookup_value (metadata,
-                                           signature_key,
-                                           signature_format);
+      OstreeSign *sign = signers->pdata[i];
+      const gchar *signature_key = ostree_sign_metadata_key (sign);
+      GVariantType *signature_format = (GVariantType *) ostree_sign_metadata_format (sign);
+      g_autoptr (GVariant) signatures =
+        g_variant_lookup_value (metadata, signature_key, signature_format);
 
       /* If not found signatures for requested signature subsystem */
       if (!signatures)
@@ -201,11 +190,7 @@ _sign_verify_for_remote (OstreeRepo *repo,
     }
 
   if (!found_sig)
-    {
-      if (n_unknown_signatures > 0)
-        return glnx_throw (error, "No signatures found (%d unknown type)", n_unknown_signatures);
-      return glnx_throw (error, "No signatures found");
-    }
+    return glnx_throw (error, "No signatures found");
 
   g_assert (last_sig_error);
   g_propagate_error (error, g_steal_pointer (&last_sig_error));

src/libostree/ostree-repo-pull.c

@@ -1544,14 +1544,11 @@ scan_commit_object (OtPullData                 *pull_data,
       gboolean found_any_signature = FALSE;
       gboolean found_valid_signature = FALSE;
 
-      /* list all signature types in detached metadata and check if signed by any? */
-      g_auto (GStrv) names = ostree_sign_list_names();
-      for (char **iter=names; iter && *iter; iter++)
+      /* FIXME - dedup this with _sign_verify_for_remote() */
+      g_autoptr(GPtrArray) signers = ostree_sign_get_all ();
+      for (guint i = 0; i < signers->len; i++)
         {
-          g_autoptr (OstreeSign) sign = NULL;
-
-          if ((sign = ostree_sign_get_by_name (*iter, NULL)) == NULL)
-            continue;
+          OstreeSign *sign = signers->pdata[i];
 
           /* Try to load public key(s) according remote's configuration */
           if (!_signapi_load_public_keys (sign, pull_data->repo, pull_data->remote_name, error))

src/libostree/ostree-sign.c

@@ -436,8 +436,6 @@ ostree_sign_commit_verify (OstreeSign     *self,
  *
  * Return the pointer to the name of currently used/selected signing engine.
  *
- * The list of available engines could be acquired with #ostree_sign_list_names.
- *
  * Returns: (transfer none): pointer to the name
  * @NULL in case of error (unlikely).
  *
@@ -515,28 +513,27 @@ ostree_sign_commit (OstreeSign     *self,
 }
 
 /**
- * ostree_sign_list_names:
+ * ostree_sign_get_all:
  *
- * Return an array with all available sign engines names.
+ * Return an array with newly allocated instances of all available
+ * signing engines; they will not be initialized.
  *
- * Returns: (transfer full): an array of strings, free when you used it
+ * Returns: (transfer full) (element-type OstreeSign): an array of signing engines
  *
  * Since: 2020.2
  */
-GStrv
-ostree_sign_list_names(void)
+GPtrArray *
+ostree_sign_get_all (void)
 {
+  g_autoptr(GPtrArray) engines = g_ptr_array_new_with_free_func (g_object_unref);
+  for (guint i = 0; i < G_N_ELEMENTS(sign_types); i++)
+    {
+      OstreeSign *engine = ostree_sign_get_by_name (sign_types[i].name, NULL);
+      g_assert (engine);
+      g_ptr_array_add (engines, engine);
+    }
 
-  GStrv names = g_new0 (char *, G_N_ELEMENTS(sign_types) + 1);
-  gint i = 0;
-
-  for (i=0; i < G_N_ELEMENTS(sign_types); i++)
-  {
-    names[i] = g_strdup(sign_types[i].name);
-    g_debug ("Found '%s' signing engine", names[i]);
-  }
-
-  return names;
+  return g_steal_pointer (&engines);
 }
 
 /**
@@ -544,11 +541,9 @@ ostree_sign_list_names(void)
  * @name: the name of desired signature engine
  * @error: return location for a #GError
  *
- * Tries to find and return proper signing engine by it's name.
+ * Create a new instance of a signing engine.
  *
- * The list of available engines could be acquired with #ostree_sign_list_names.
- *
- * Returns: (transfer full): a constant, free when you used it
+ * Returns: (transfer full): New signing engine, or %NULL if the engine is not known
  *
  * Since: 2020.2
  */

src/libostree/ostree-sign.h

@@ -153,7 +153,7 @@ gboolean ostree_sign_load_pk (OstreeSign *self,
 
 
 _OSTREE_PUBLIC
-GStrv ostree_sign_list_names(void);
+GPtrArray * ostree_sign_get_all(void);
 
 _OSTREE_PUBLIC
 OstreeSign * ostree_sign_get_by_name (const gchar *name, GError **error);