gpg: add dummy public interface

Add dummy stubs for GPG public functions to be compiled instead of
original code in case if support of GPG is disabled.
Need that to keep API backward compatibility.

Based on original code from file `ostree-gpg-verify-result.c`.

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>

Closes: #1889
Approved by: cgwalters

2 files changed, 307 insertions, 0 deletions

diff --git a/Makefile-libostree.am b/Makefile-libostree.am
index 61763f95..46984a75 100644
--- a/Makefile-libostree.am
+++ b/Makefile-libostree.am
@@ -172,6 +172,10 @@ libostree_1_la_SOURCES += \
 	src/libostree/ostree-gpg-verify-result.c \
 	src/libostree/ostree-gpg-verify-result-private.h \
 	$(NULL)
+else
+libostree_1_la_SOURCES += \
+	src/libostree/ostree-gpg-verify-result-dummy.c \
+	$(NULL)
 endif # USE_GPGME
 
 symbol_files = $(top_srcdir)/src/libostree/libostree-released.sym
diff --git a/src/libostree/ostree-gpg-verify-result-dummy.c b/src/libostree/ostree-gpg-verify-result-dummy.c
new file mode 100644
index 00000000..a62ff915
--- /dev/null
+++ b/src/libostree/ostree-gpg-verify-result-dummy.c
@@ -0,0 +1,303 @@
+/*
+ * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (C) 2019 Collabora Ltd.
+ *
+ * SPDX-License-Identifier: LGPL-2.0+
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include "libglnx.h"
+
+#include "ostree-gpg-verify-result.h"
+
+/**
+ * SECTION: ostree-gpg-verify-result
+ * @title: GPG signature verification results
+ * @short_description: Dummy functions for detached GPG signatures
+ *
+ * This file contain dummy functions for GPG signatures checks to
+ * provide API backward compatibility.
+ */
+
+#ifndef OSTREE_DISABLE_GPGME
+#error This file should not be compiled if GPG support is enabled
+#endif
+
+/**
+ * OstreeGpgVerifyResult:
+ *
+ * Private instance structure.
+ */
+struct OstreeGpgVerifyResult {
+  GObject parent;
+};
+
+
+typedef struct {
+  GObjectClass parent_class;
+} OstreeGpgVerifyResultClass;
+
+static void ostree_gpg_verify_result_initable_iface_init (GInitableIface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (OstreeGpgVerifyResult,
+                         ostree_gpg_verify_result,
+                         G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
+                                                ostree_gpg_verify_result_initable_iface_init))
+
+static void
+ostree_gpg_verify_result_class_init (OstreeGpgVerifyResultClass *class)
+{
+}
+
+static void
+ostree_gpg_verify_result_initable_iface_init (GInitableIface *iface)
+{
+}
+
+static void
+ostree_gpg_verify_result_init (OstreeGpgVerifyResult *result)
+{
+}
+
+/**
+ * ostree_gpg_verify_result_count_all:
+ * @result: an #OstreeGpgVerifyResult
+ *
+ * Counts all the signatures in @result.
+ *
+ * Returns: signature count
+ */
+guint
+ostree_gpg_verify_result_count_all (OstreeGpgVerifyResult *result)
+{
+  g_critical ("%s: GPG feature is disabled in a build time", __FUNCTION__);
+  return 0;
+}
+
+/**
+ * ostree_gpg_verify_result_count_valid:
+ * @result: an #OstreeGpgVerifyResult
+ *
+ * Counts only the valid signatures in @result.
+ *
+ * Returns: valid signature count
+ */
+guint
+ostree_gpg_verify_result_count_valid (OstreeGpgVerifyResult *result)
+{
+  g_critical ("%s: GPG feature is disabled in a build time", __FUNCTION__);
+  return 0;
+}
+
+/**
+ * ostree_gpg_verify_result_lookup:
+ * @result: an #OstreeGpgVerifyResult
+ * @key_id: a GPG key ID or fingerprint
+ * @out_signature_index: (out): return location for the index of the signature
+ *                              signed by @key_id, or %NULL
+ *
+ * Searches @result for a signature signed by @key_id.  If a match is found,
+ * the function returns %TRUE and sets @out_signature_index so that further
+ * signature details can be obtained through ostree_gpg_verify_result_get().
+ * If no match is found, the function returns %FALSE and leaves
+ * @out_signature_index unchanged.
+ *
+ * Returns: %TRUE on success, %FALSE on failure
+ **/
+gboolean
+ostree_gpg_verify_result_lookup (OstreeGpgVerifyResult *result,
+                                 const gchar *key_id,
+                                 guint *out_signature_index)
+{
+  g_critical ("%s: GPG feature is disabled in a build time", __FUNCTION__);
+  return FALSE;
+}
+
+/**
+ * ostree_gpg_verify_result_get:
+ * @result: an #OstreeGpgVerifyResult
+ * @signature_index: which signature to get attributes from
+ * @attrs: (array length=n_attrs): Array of requested attributes
+ * @n_attrs: Length of the @attrs array
+ *
+ * Builds a #GVariant tuple of requested attributes for the GPG signature at
+ * @signature_index in @result.  See the #OstreeGpgSignatureAttr description
+ * for the #GVariantType of each available attribute.
+ *
+ * It is a programmer error to request an invalid #OstreeGpgSignatureAttr or
+ * an invalid @signature_index.  Use ostree_gpg_verify_result_count_all() to
+ * find the number of signatures in @result.
+ *
+ * Returns: a new, floating, #GVariant tuple
+ **/
+GVariant *
+ostree_gpg_verify_result_get (OstreeGpgVerifyResult *result,
+                              guint signature_index,
+                              OstreeGpgSignatureAttr *attrs,
+                              guint n_attrs)
+{
+  g_critical ("%s: GPG feature is disabled in a build time", __FUNCTION__);
+  return NULL;
+}
+
+/**
+ * ostree_gpg_verify_result_get_all:
+ * @result: an #OstreeGpgVerifyResult
+ * @signature_index: which signature to get attributes from
+ *
+ * Builds a #GVariant tuple of all available attributes for the GPG signature
+ * at @signature_index in @result.
+ *
+ * The child values in the returned #GVariant tuple are ordered to match the
+ * #OstreeGpgSignatureAttr enumeration, which means the enum values can be
+ * used as index values in functions like g_variant_get_child().  See the
+ * #OstreeGpgSignatureAttr description for the #GVariantType of each
+ * available attribute.
+ *
+ * <note>
+ *   <para>
+ *     The #OstreeGpgSignatureAttr enumeration may be extended in the future
+ *     with new attributes, which would affect the #GVariant tuple returned by
+ *     this function.  While the position and type of current child values in
+ *     the #GVariant tuple will not change, to avoid backward-compatibility
+ *     issues <emphasis>please do not depend on the tuple's overall size or
+ *     type signature</emphasis>.
+ *   </para>
+ * </note>
+ *
+ * It is a programmer error to request an invalid @signature_index.  Use
+ * ostree_gpg_verify_result_count_all() to find the number of signatures in
+ * @result.
+ *
+ * Returns: a new, floating, #GVariant tuple
+ **/
+GVariant *
+ostree_gpg_verify_result_get_all (OstreeGpgVerifyResult *result,
+                                  guint signature_index)
+{
+  g_return_val_if_fail (OSTREE_IS_GPG_VERIFY_RESULT (result), NULL);
+
+  g_critical ("%s: GPG feature is disabled in a build time", __FUNCTION__);
+  return NULL;
+}
+
+/**
+ * ostree_gpg_verify_result_describe:
+ * @result: an #OstreeGpgVerifyResult
+ * @signature_index: which signature to describe
+ * @output_buffer: a #GString to hold the description
+ * @line_prefix: (allow-none): optional line prefix string
+ * @flags: flags to adjust the description format
+ *
+ * Appends a brief, human-readable description of the GPG signature at
+ * @signature_index in @result to the @output_buffer.  The description
+ * spans multiple lines.  A @line_prefix string, if given, will precede
+ * each line of the description.
+ *
+ * The @flags argument is reserved for future variations to the description
+ * format.  Currently must be 0.
+ *
+ * It is a programmer error to request an invalid @signature_index.  Use
+ * ostree_gpg_verify_result_count_all() to find the number of signatures in
+ * @result.
+ */
+void
+ostree_gpg_verify_result_describe (OstreeGpgVerifyResult *result,
+                                   guint signature_index,
+                                   GString *output_buffer,
+                                   const gchar *line_prefix,
+                                   OstreeGpgSignatureFormatFlags flags)
+{
+  g_autoptr(GVariant) variant = NULL;
+
+  g_return_if_fail (OSTREE_IS_GPG_VERIFY_RESULT (result));
+
+  g_critical ("%s: GPG feature is disabled in a build time", __FUNCTION__);
+
+  variant = ostree_gpg_verify_result_get_all (result, signature_index);
+
+  ostree_gpg_verify_result_describe_variant (variant, output_buffer, line_prefix, flags);
+}
+
+/**
+ * ostree_gpg_verify_result_describe_variant:
+ * @variant: a #GVariant from ostree_gpg_verify_result_get_all()
+ * @output_buffer: a #GString to hold the description
+ * @line_prefix: (allow-none): optional line prefix string
+ * @flags: flags to adjust the description format
+ *
+ * Similar to ostree_gpg_verify_result_describe() but takes a #GVariant of
+ * all attributes for a GPG signature instead of an #OstreeGpgVerifyResult
+ * and signature index.
+ *
+ * The @variant <emphasis>MUST</emphasis> have been created by
+ * ostree_gpg_verify_result_get_all().
+ */
+void
+ostree_gpg_verify_result_describe_variant (GVariant *variant,
+                                           GString *output_buffer,
+                                           const gchar *line_prefix,
+                                           OstreeGpgSignatureFormatFlags flags)
+{
+  const char *type_string;
+
+  g_return_if_fail (variant != NULL);
+  g_return_if_fail (output_buffer != NULL);
+
+  /* Verify the variant's type string.  This code is
+   * not prepared to handle just any random GVariant. */
+  type_string = g_variant_get_type_string (variant);
+  g_return_if_fail (strcmp (type_string, "(bbbbbsxxsssssxx)") == 0);
+
+  g_string_append (output_buffer,
+                   "GPG feature is disabled in a build time\n");
+
+  g_critical ("%s: GPG feature is disabled in a build time", __FUNCTION__);
+}
+
+/**
+ * ostree_gpg_verify_result_require_valid_signature:
+ * @result: (nullable): an #OstreeGpgVerifyResult
+ * @error: A #GError
+ *
+ * Checks if the result contains at least one signature from the
+ * trusted keyring.  You can call this function immediately after
+ * ostree_repo_verify_summary() or ostree_repo_verify_commit_ext() -
+ * it will handle the %NULL @result and filled @error too.
+ *
+ * Returns: %TRUE if @result was not %NULL and had at least one
+ * signature from trusted keyring, otherwise %FALSE
+ *
+ * Since: 2016.6
+ */
+gboolean
+ostree_gpg_verify_result_require_valid_signature (OstreeGpgVerifyResult *result,
+                                                  GError **error)
+{
+  if (result == NULL)
+    return FALSE;
+
+  g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+               "'%s': GPG feature is disabled in a build time",
+               __FUNCTION__);
+  return FALSE;
+}
+
+G_DEFINE_QUARK (OstreeGpgError, ostree_gpg_error)