=== modified file 'src/polkit-grant/polkit-grant-helper.c'
--- src/polkit-grant/polkit-grant-helper.c	2008-10-08 23:49:32 +0000
+++ src/polkit-grant/polkit-grant-helper.c	2009-04-13 13:01:21 +0000
@@ -136,12 +136,15 @@
  *
  *   Receive PAM request on stdin.
  *   Program deals with it.
- *   Write reply on stdout
+ *   Write reply on stdout if one is
+ *   needed
  *
- *                                       Receive PAM reply on stdin
+ *                                       If a PAM reply is needed then read
+ *                                       it on stdin then
  *                                       Send PAM reply on stdout
  *
- *                                                                         Deal with PAM reply on stdin.
+ *                                                                         If awaiting a PAM reply on stdin then deal
+ *                                                                         with it.
  *                                                                         Now either
  *                                                                         - GOTO auth_in_progress; or
  *                                                                         - Write SUCCESS|FAILURE on stdout and then
@@ -163,6 +166,34 @@
  */
 
 
+/**
+ * requires_reply:
+ *
+ * inspect the message that the child is sending to the parent and
+ * decide whether the child will be expecting a response from the parent.
+ */
+gboolean
+requires_reply (const char *message)
+{
+    if (strncmp(message, "PAM_PROMPT_ECHO_OFF ",
+                sizeof "PAM_PROMPT_ECHO_OFF " - 1) == 0) {
+        return TRUE;
+    }
+    if (strncmp(message, "PAM_PROMPT_ECHO_ON ",
+                sizeof "PAM_PROMPT_ECHO_ON " - 1) == 0) {
+        return TRUE;
+    }
+    if (strncmp(message, "POLKIT_GRANT_HELPER_TELL_ADMIN_USERS ",
+                sizeof "POLKIT_GRANT_HELPER_TELL_ADMIN_USERS " - 1) == 0) {
+        return TRUE;
+    }
+    if (strncmp(message, "POLKIT_GRANT_HELPER_ASK_OVERRIDE_GRANT_TYPE ",
+                sizeof "POLKIT_GRANT_HELPER_ASK_OVERRIDE_GRANT_TYPE " - 1) == 0) {
+        return TRUE;
+    }
+    return FALSE;
+}
+
 /** 
  * do_auth:
  * 
@@ -250,16 +281,18 @@
                 fprintf (stdout, "%s", buf);
                 fflush (stdout);
                 
-                /* read from parent */
-                if (fgets (buf, sizeof buf, stdin) == NULL)
-                        goto out;
+                if (requires_reply (buf)) {
+                    /* read from parent */
+                    if (fgets (buf, sizeof buf, stdin) == NULL)
+                            goto out;
 
 #ifdef PGH_DEBUG
-                fprintf (stderr, "received: '%s' from parent; sending to child\n", buf);
+                    fprintf (stderr, "received: '%s' from parent; sending to child\n", buf);
 #endif /* PGH_DEBUG */
-                /* send to child */
-                fprintf (child_stdin, "%s", buf);
-                fflush (child_stdin);
+                    /* send to child */
+                    fprintf (child_stdin, "%s", buf);
+                    fflush (child_stdin);
+                }
         }
 
 out: