Merge pull request #118 from glyptodon/user-validity-race
GUAC-1389: Fix user validity race.
This commit is contained in:
commit
21d700f633
@ -104,6 +104,36 @@ void guac_common_cursor_dup(guac_common_cursor* cursor, guac_user* user,
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}
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/**
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* Callback for guac_client_for_user() which shows the cursor layer for the
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* given user (if they exist). The cursor layer is normally hidden when a user
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* is moving the mouse, and will only be shown if a DIFFERENT user is moving
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* the mouse.
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*
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* @param user
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* The user to show the cursor to, or NULL if that user does not exist.
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*
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* @param data
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* A pointer to the guac_common_cursor structure describing the cursor to
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* be shown.
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*
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* @return
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* Always NULL.
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*/
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static void* guac_common_cursor_show(guac_user* user, void* data) {
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guac_common_cursor* cursor = (guac_common_cursor*) data;
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/* Make cursor layer visible to given user */
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if (user != NULL) {
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guac_protocol_send_shade(user->socket, cursor->layer, 255);
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guac_socket_flush(user->socket);
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}
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return NULL;
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}
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void guac_common_cursor_move(guac_common_cursor* cursor, guac_user* user,
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int x, int y) {
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@ -115,10 +145,8 @@ void guac_common_cursor_move(guac_common_cursor* cursor, guac_user* user,
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cursor->user = user;
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/* Make cursor layer visible to previous user */
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if (last_user != NULL) {
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guac_protocol_send_shade(last_user->socket, cursor->layer, 255);
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guac_socket_flush(last_user->socket);
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}
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guac_client_for_user(cursor->client, last_user,
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guac_common_cursor_show, cursor);
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/* Show hardware cursor */
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guac_protocol_send_cursor(user->socket,
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@ -208,6 +236,40 @@ static void* __send_user_cursor_image(guac_user* user, void* data) {
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}
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/**
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* Callback for guac_client_for_user() which updates the hardware cursor and
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* hotspot for the given user (if they exist). The hardware cursor image is
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* normally hidden when a user is not moving the mouse, and will only be shown
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* if that user begins moving the mouse.
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*
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* @param user
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* The user whose hardware cursor should be updated, or NULL if that user
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* does not exist.
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*
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* @param data
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* A pointer to the guac_common_cursor structure describing the cursor to
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* be sent as the hardware cursor.
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*
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* @return
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* Always NULL.
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*/
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static void* guac_common_cursor_update(guac_user* user, void* data) {
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guac_common_cursor* cursor = (guac_common_cursor*) data;
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/* Update hardware cursor of current user */
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if (user != NULL) {
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guac_protocol_send_cursor(user->socket,
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cursor->hotspot_x, cursor->hotspot_y,
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cursor->layer, 0, 0, cursor->width, cursor->height);
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guac_socket_flush(user->socket);
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}
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return NULL;
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}
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void guac_common_cursor_set_argb(guac_common_cursor* cursor, int hx, int hy,
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unsigned const char* data, int width, int height, int stride) {
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@ -242,13 +304,10 @@ void guac_common_cursor_set_argb(guac_common_cursor* cursor, int hx, int hy,
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guac_socket_flush(cursor->client->socket);
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/* Update hardware cursor of current user */
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if (cursor->user != NULL) {
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guac_protocol_send_cursor(cursor->user->socket, hx, hy,
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cursor->layer, 0, 0, width, height);
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guac_socket_flush(cursor->user->socket);
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}
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/* Update hardware cursor of current user (if they are indeed valid) */
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if (cursor->user != NULL)
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guac_client_for_user(cursor->client, cursor->user,
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guac_common_cursor_update, cursor);
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}
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@ -303,12 +362,3 @@ void guac_common_cursor_set_blank(guac_common_cursor* cursor) {
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}
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void guac_common_cursor_remove_user(guac_common_cursor* cursor,
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guac_user* user) {
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/* Disassociate from given user */
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if (cursor->user == user)
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cursor->user = NULL;
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}
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@ -252,19 +252,4 @@ void guac_common_cursor_set_ibar(guac_common_cursor* cursor);
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*/
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void guac_common_cursor_set_blank(guac_common_cursor* cursor);
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/**
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* Removes the given user, such that future synchronization will not occur.
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* This is necessary when a user leaves the connection. If a user leaves the
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* connection and this is not called, the corresponding guac_user and socket
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* may cease to be valid, and future synchronization attempts will segfault.
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*
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* @param cursor
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* The cursor to remove the user from.
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*
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* @param user
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* The user to remove.
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*/
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void guac_common_cursor_remove_user(guac_common_cursor* cursor,
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guac_user* user);
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#endif
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@ -637,6 +637,43 @@ void* guac_client_for_owner(guac_client* client, guac_user_callback* callback,
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}
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void* guac_client_for_user(guac_client* client, guac_user* user,
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guac_user_callback* callback, void* data) {
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guac_user* current;
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int user_valid = 0;
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void* retval;
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pthread_rwlock_rdlock(&(client->__users_lock));
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/* Loop through all users, searching for a pointer to the given user */
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current = client->__users;
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while (current != NULL) {
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/* If the user's pointer exists in the list, they are indeed valid */
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if (current == user) {
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user_valid = 1;
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break;
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}
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current = current->__next;
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}
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/* Use NULL if user does not actually exist */
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if (!user_valid)
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user = NULL;
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/* Invoke callback with requested user (if they exist) */
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retval = callback(user, data);
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pthread_rwlock_unlock(&(client->__users_lock));
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/* Return value from callback */
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return retval;
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}
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int guac_client_end_frame(guac_client* client) {
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/* Update and send timestamp */
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@ -457,14 +457,10 @@ void guac_client_foreach_user(guac_client* client,
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guac_user_callback* callback, void* data);
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/**
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* Retrieves the connected user that is marked as the owner. The owner of a
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* connection is the user that established the initial connection that created
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* the connection (the first user to connect and join).
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*
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* Calls the given function on with the currently-connected user that is marked
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* as the owner. The owner of a connection is the user that established the
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* Calls the given function with the currently-connected user that is marked as
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* the owner. The owner of a connection is the user that established the
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* initial connection that created the connection (the first user to connect
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* and join). The function will be given a reference to a guac_user and the
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* and join). The function will be given a reference to the guac_user and the
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* specified arbitrary data. If the owner has since left the connection, the
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* function will instead be invoked with NULL as the guac_user. The value
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* returned by the callback will be returned by this function.
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@ -480,12 +476,58 @@ void guac_client_foreach_user(guac_client* client,
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* @param client
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* The client to retrieve the owner from.
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*
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* @param callback
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* The callback to invoke on the user marked as the owner of the
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* connection. NULL will be passed to this callback instead if there is no
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* owner.
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*
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* @param data
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* Arbitrary data to pass to the given callback.
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*
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* @return
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* The value returned by the callback.
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*/
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void* guac_client_for_owner(guac_client* client, guac_user_callback* callback,
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void* data);
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/**
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* Calls the given function with the given user ONLY if they are currently
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* connected. The function will be given a reference to the guac_user and the
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* specified arbitrary data. If the provided user doesn't exist or has since
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* left the connection, the function will instead be invoked with NULL as the
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* guac_user. The value returned by the callback will be returned by this
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* function.
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*
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* This function is reentrant, but the user list MUST NOT be manipulated
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* within the same thread as a callback to this function.
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*
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* Because this function depends on a consistent list of connected users, this
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* function MUST NOT be invoked within the same thread as a "leave" or "join"
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* handler. Doing so results in undefined behavior, including possible
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* segfaults.
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*
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* @param client
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* The client that the given user is expected to be associated with.
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*
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* @param user
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* The user to provide to the given callback if valid. The pointer need not
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* even point to properly allocated memory; the user will only be passed to
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* the callback function if they are valid, and the provided user pointer
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* will not be dereferenced during this process.
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*
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* @param callback
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* The callback to invoke on the given user if they are valid. NULL will be
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* passed to this callback instead if the user is not valid.
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*
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* @param data
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* Arbitrary data to pass to the given callback.
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*
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* @return
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* The value returned by the callback.
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*/
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void* guac_client_for_user(guac_client* client, guac_user* user,
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guac_user_callback* callback, void* data);
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/**
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* Marks the end of the current frame by sending a "sync" instruction to
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* all connected users. This instruction will contain the current timestamp.
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@ -100,12 +100,3 @@ int guac_vnc_user_join_handler(guac_user* user, int argc, char** argv) {
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}
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int guac_vnc_user_leave_handler(guac_user* user) {
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guac_vnc_client* vnc_client = (guac_vnc_client*) user->client->data;
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guac_common_cursor_remove_user(vnc_client->display->cursor, user);
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return 0;
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}
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@ -32,10 +32,5 @@
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*/
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guac_user_join_handler guac_vnc_user_join_handler;
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/**
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* Handler for leaving users.
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*/
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guac_user_leave_handler guac_vnc_user_leave_handler;
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#endif
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