GCredentials: Add the concept of credentials that lack the process ID

struct xucred on macOS doesn't have the process ID, only the user ID
and groups.

Signed-off-by: Simon McVittie <smcv@collabora.com>

gio/gcredentialsprivate.h

@@ -93,6 +93,13 @@
  */
 #undef G_CREDENTIALS_PREFER_MESSAGE_PASSING
 
+/*
+ * G_CREDENTIALS_HAS_PID:
+ *
+ * Defined to 1 if the %G_CREDENTIALS_NATIVE_TYPE contains the process ID.
+ */
+#undef G_CREDENTIALS_HAS_PID
+
 #ifdef __linux__
 #define G_CREDENTIALS_SUPPORTED 1
 #define G_CREDENTIALS_USE_LINUX_UCRED 1
@@ -101,6 +108,7 @@
 #define G_CREDENTIALS_UNIX_CREDENTIALS_MESSAGE_SUPPORTED 1
 #define G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED 1
 #define G_CREDENTIALS_SPOOFING_SUPPORTED 1
+#define G_CREDENTIALS_HAS_PID 1
 
 #elif defined(__FreeBSD__)                                  || \
       defined(__FreeBSD_kernel__) /* Debian GNU/kFreeBSD */ || \
@@ -118,6 +126,7 @@
  * SCM_CREDS, and if we implement getpeereid() in future, we should
  * do the same. */
 #define G_CREDENTIALS_PREFER_MESSAGE_PASSING 1
+#define G_CREDENTIALS_HAS_PID 1
 
 #elif defined(__NetBSD__)
 #define G_CREDENTIALS_SUPPORTED 1
@@ -126,6 +135,7 @@
 #define G_CREDENTIALS_NATIVE_SIZE (sizeof (struct unpcbid))
 /* #undef G_CREDENTIALS_UNIX_CREDENTIALS_MESSAGE_SUPPORTED */
 #define G_CREDENTIALS_SPOOFING_SUPPORTED 1
+#define G_CREDENTIALS_HAS_PID 1
 
 #elif defined(__OpenBSD__)
 #define G_CREDENTIALS_SUPPORTED 1
@@ -134,6 +144,7 @@
 #define G_CREDENTIALS_NATIVE_SIZE (sizeof (struct sockpeercred))
 #define G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED 1
 #define G_CREDENTIALS_SPOOFING_SUPPORTED 1
+#define G_CREDENTIALS_HAS_PID 1
 
 #elif defined(__sun__) || defined(__illumos__) || defined (__OpenSolaris_kernel__)
 #include <ucred.h>
@@ -143,6 +154,7 @@
 #define G_CREDENTIALS_NATIVE_SIZE (ucred_size ())
 #define G_CREDENTIALS_UNIX_CREDENTIALS_MESSAGE_SUPPORTED 1
 #define G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED 1
+#define G_CREDENTIALS_HAS_PID 1
 
 #endif
 

gio/tests/credentials.c

@@ -54,9 +54,16 @@ test_basic (void)
   g_assert_cmpuint (g_credentials_get_unix_user (creds, &error), ==,
       geteuid ());
   g_assert_no_error (error);
-  g_assert_cmpuint (g_credentials_get_unix_pid (creds, &error), ==,
+
+#if G_CREDENTIALS_HAS_PID
+  g_assert_cmpint (g_credentials_get_unix_pid (creds, &error), ==,
       getpid ());
   g_assert_no_error (error);
+#else
+  g_assert_cmpint (g_credentials_get_unix_pid (creds, &error), ==, -1);
+  g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED);
+  g_clear_error (&error);
+#endif
 
   set = g_credentials_set_unix_user (other, not_me, &error);
 #if G_CREDENTIALS_SPOOFING_SUPPORTED

gio/tests/gdbus-peer.c

@@ -344,7 +344,7 @@ on_new_connection (GDBusServer *server,
                    gpointer user_data)
 {
   PeerData *data = user_data;
-  GError *error;
+  GError *error = NULL;
   guint reg_id;
 
   //g_printerr ("Client connected.\n"
@@ -362,13 +362,19 @@ on_new_connection (GDBusServer *server,
       g_assert (credentials != NULL);
       g_assert_cmpuint (g_credentials_get_unix_user (credentials, NULL), ==,
                         getuid ());
-      g_assert_cmpuint (g_credentials_get_unix_pid (credentials, NULL), ==,
+#if G_CREDENTIALS_HAS_PID
+      g_assert_cmpint (g_credentials_get_unix_pid (credentials, &error), ==,
                        getpid ());
+      g_assert_no_error (error);
+#else
+      g_assert_cmpint (g_credentials_get_unix_pid (credentials, &error), ==, -1);
+      g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED);
+      g_clear_error (&error);
+#endif
     }
 #endif
 
   /* export object on the newly established connection */
-  error = NULL;
   reg_id = g_dbus_connection_register_object (connection,
                                               "/org/gtk/GDBus/PeerTestObject",
                                               test_interface_introspection_data,
@@ -922,8 +928,15 @@ do_test_peer (void)
 
     g_assert_cmpuint (g_credentials_get_unix_user (credentials, NULL), ==,
                       getuid ());
-    g_assert_cmpuint (g_credentials_get_unix_pid (credentials, NULL), ==,
+#if G_CREDENTIALS_HAS_PID
+    g_assert_cmpint (g_credentials_get_unix_pid (credentials, &error), ==,
                      getpid ());
+    g_assert_no_error (error);
+#else
+    g_assert_cmpint (g_credentials_get_unix_pid (credentials, &error), ==, -1);
+    g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED);
+    g_clear_error (&error);
+#endif
     g_object_unref (credentials);
 #else
     g_assert_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED);