From 92e2f4e42074693bdc540ec9d0ae7392c7771a65 Mon Sep 17 00:00:00 2001
From: Michael Jumper <mjumper@apache.org>
Date: Mon, 18 Apr 2016 18:53:12 -0700
Subject: [PATCH] GUACAMOLE-33: Restore guac_common_cursor_remove_user()
 (reverts commit af7968e).

---
 src/common/guac_cursor.c |  9 +++++++++
 src/common/guac_cursor.h | 15 +++++++++++++++
 src/protocols/vnc/user.c |  9 +++++++++
 src/protocols/vnc/user.h |  5 +++++
 4 files changed, 38 insertions(+)

diff --git a/src/common/guac_cursor.c b/src/common/guac_cursor.c
index e376ab03..4ed66b1d 100644
--- a/src/common/guac_cursor.c
+++ b/src/common/guac_cursor.c
@@ -367,3 +367,12 @@ void guac_common_cursor_set_blank(guac_common_cursor* cursor) {
 
 }
 
+void guac_common_cursor_remove_user(guac_common_cursor* cursor,
+        guac_user* user) {
+
+    /* Disassociate from given user */
+    if (cursor->user == user)
+        cursor->user = NULL;
+
+}
+
diff --git a/src/common/guac_cursor.h b/src/common/guac_cursor.h
index ae359b7f..9db7067d 100644
--- a/src/common/guac_cursor.h
+++ b/src/common/guac_cursor.h
@@ -249,4 +249,19 @@ void guac_common_cursor_set_ibar(guac_common_cursor* cursor);
  */
 void guac_common_cursor_set_blank(guac_common_cursor* cursor);
 
+/**
+ * Removes the given user, such that future synchronization will not occur.
+ * This is necessary when a user leaves the connection. If a user leaves the
+ * connection and this is not called, the corresponding guac_user and socket
+ * may cease to be valid, and future synchronization attempts will segfault.
+ *
+ * @param cursor
+ *     The cursor to remove the user from.
+ *
+ * @param user
+ *     The user to remove.
+ */
+void guac_common_cursor_remove_user(guac_common_cursor* cursor,
+        guac_user* user);
+
 #endif
diff --git a/src/protocols/vnc/user.c b/src/protocols/vnc/user.c
index 0b89d7c9..53423a11 100644
--- a/src/protocols/vnc/user.c
+++ b/src/protocols/vnc/user.c
@@ -97,3 +97,12 @@ int guac_vnc_user_join_handler(guac_user* user, int argc, char** argv) {
 
 }
 
+int guac_vnc_user_leave_handler(guac_user* user) {
+
+    guac_vnc_client* vnc_client = (guac_vnc_client*) user->client->data;
+
+    guac_common_cursor_remove_user(vnc_client->display->cursor, user);
+
+    return 0;
+}
+
diff --git a/src/protocols/vnc/user.h b/src/protocols/vnc/user.h
index 125e4965..e74b2a05 100644
--- a/src/protocols/vnc/user.h
+++ b/src/protocols/vnc/user.h
@@ -29,5 +29,10 @@
  */
 guac_user_join_handler guac_vnc_user_join_handler;
 
+/**
+ * Handler for leaving users.
+ */
+guac_user_leave_handler guac_vnc_user_leave_handler;
+
 #endif