sysdeps: Give a more useful error if unable to resolve a numeric uid

If we want to get the struct passwd corresponding to uid 42, but we
can't, it's much better to say

    User ID "42" unknown

rather than

    User "???" unknown

Helps: https://gitlab.freedesktop.org/dbus/dbus/-/issues/343
Signed-off-by: Simon McVittie <smcv@collabora.com>

diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
index 4dfdf549413fbc0716ba99510d914505a4f829d6..d08516ab5c797fc3c41a4206fe2229f96ddfe9c3 100644 (file)
--- a/dbus/dbus-sysdeps-unix.c
+++ b/dbus/dbus-sysdeps-unix.c
@@ -2797,10 +2797,19 @@ fill_user_info (DBusUserInfo       *info,
       }
     else
       {
-        dbus_set_error (error, _dbus_error_from_errno (errno),
-                        "User \"%s\" unknown or no memory to allocate password entry\n",
-                        username_c ? username_c : "???");
-        _dbus_verbose ("User %s unknown\n", username_c ? username_c : "???");
+        DBusError local_error = DBUS_ERROR_INIT;
+
+        if (uid != DBUS_UID_UNSET)
+          dbus_set_error (&local_error, _dbus_error_from_errno (errno),
+                          "User ID " DBUS_UID_FORMAT " unknown or no memory to allocate password entry",
+                          uid);
+        else
+          dbus_set_error (&local_error, _dbus_error_from_errno (errno),
+                          "User \"%s\" unknown or no memory to allocate password entry\n",
+                          username_c ? username_c : "???");
+
+        _dbus_verbose ("%s", local_error.message);
+        dbus_move_error (&local_error, error);
         dbus_free (buf);
         return FALSE;
       }