lib/repo: Search a list of paths in gpgkeypath for gpg keys

This allows specifying gpgpath as list of
paths that can point to a file or a directory. If a directory path
is given, paths to all regular files in the directory are added
to the remote as gpg ascii keys. If the path is not a directory,
the file is directly added (whether regular file, empty - errors
will be reported later when verifying gpg keys e.g. when pulling).

Adding the gpgkeypath property looks like:

ostree --repo=repo remote add --set=gpgpath="/path/key1.asc,/path/keys.d" R1 https://example.com/some/remote/ostree/repo

Closes #773

Closes: #1773
Approved by: cgwalters

src/libotutil/ot-keyfile-utils.c

@@ -101,6 +101,107 @@ ot_keyfile_get_value_with_default (GKeyFile      *keyfile,
   return ret;
 }
 
+/* Read the value of key as a string. If the value string contains
+ * one of the separators and none of the others, read the
+ * string as a NULL-terminated array out_value. If the value string contains
+ * none of the separators, read the string as a single entry into a
+ * NULL-terminated array out_value. If the value string contains multiple of
+ * the separators, an error is given.
+ * Returns TRUE on success, FALSE on error. */
+gboolean
+ot_keyfile_get_string_as_list (GKeyFile      *keyfile,
+                               const char    *section,
+                               const char    *key,
+                               const char    *separators,
+                               char        ***out_value,
+                               GError       **error)
+{
+  guint sep_count = 0;
+  gchar sep = '\0';
+  g_autofree char  *value_str = NULL;
+  g_autofree char **value_list = NULL;
+
+  g_return_val_if_fail (keyfile != NULL, FALSE);
+  g_return_val_if_fail (section != NULL, FALSE);
+  g_return_val_if_fail (key != NULL, FALSE);
+  g_return_val_if_fail (separators != NULL, FALSE);
+
+  if (!ot_keyfile_get_value_with_default (keyfile, section, key, NULL,
+                                          &value_str, error))
+    return FALSE;
+
+  if (value_str)
+    {
+      for (size_t i = 0; i < strlen (separators) && sep_count <= 1; i++)
+        {
+          if (strchr (value_str, separators[i]))
+            {
+              sep_count++;
+              sep = separators[i];
+            }
+        }
+
+      if (sep_count == 0)
+        {
+          value_list = g_new (gchar *, 2);
+          value_list[0] = g_steal_pointer (&value_str);
+          value_list[1] = NULL;
+        }
+      else if (sep_count == 1)
+        {
+          if (!ot_keyfile_get_string_list_with_default (keyfile, section, key,
+                                                        sep, NULL, &value_list, error))
+            return FALSE;
+        }
+      else
+        {
+          return glnx_throw (error, "key value list contains more than one separator");
+        }
+    }
+
+  ot_transfer_out_value (out_value, &value_list);
+  return TRUE;
+}
+
+gboolean
+ot_keyfile_get_string_list_with_default (GKeyFile      *keyfile,
+                                         const char    *section,
+                                         const char    *key,
+                                         char           separator,
+                                         char         **default_value,
+                                         char        ***out_value,
+                                         GError       **error)
+{
+  g_autoptr(GError) temp_error = NULL;
+
+  g_return_val_if_fail (keyfile != NULL, FALSE);
+  g_return_val_if_fail (section != NULL, FALSE);
+  g_return_val_if_fail (key != NULL, FALSE);
+
+  g_key_file_set_list_separator (keyfile, separator);
+
+  g_autofree char **ret_value = g_key_file_get_string_list (keyfile, section,
+                                                            key, NULL, &temp_error);
+
+  if (temp_error)
+    {
+      if (g_error_matches (temp_error, G_KEY_FILE_ERROR,
+                           G_KEY_FILE_ERROR_KEY_NOT_FOUND))
+        {
+          g_clear_error (&temp_error);
+          ret_value = default_value;
+        }
+      else
+        {
+          g_propagate_error (error, g_steal_pointer (&temp_error));
+          return FALSE;
+        }
+    }
+
+  ot_transfer_out_value (out_value, &ret_value);
+  return TRUE;
+}
+
 gboolean
 ot_keyfile_copy_group (GKeyFile   *source_keyfile,
                        GKeyFile   *target_keyfile,

src/libotutil/ot-keyfile-utils.h

@@ -44,6 +44,23 @@ ot_keyfile_get_value_with_default (GKeyFile      *keyfile,
                                    char         **out_value,
                                    GError       **error);
 
+gboolean
+ot_keyfile_get_string_as_list (GKeyFile      *keyfile,
+                               const char    *section,
+                               const char    *key,
+                               const char    *separators,
+                               char        ***out_value_list,
+                               GError       **error);
+
+gboolean
+ot_keyfile_get_string_list_with_default (GKeyFile      *keyfile,
+                                         const char    *section,
+                                         const char    *key,
+                                         char           separator,
+                                         char         **default_value,
+                                         char        ***out_value,
+                                         GError       **error);
+
 gboolean
 ot_keyfile_copy_group (GKeyFile   *source_keyfile,
                        GKeyFile   *target_keyfile,