epoptes team mailing list archive

[Laércio de Sousa <lbsousajr@xxxxxxxxx>]

Laércio de Sousa has proposed merging lp:~oiteam/epoptes/x11vnc-wrapper-with-alt-input-grabbing into lp:epoptes.

Requested reviews:
  Epoptes Developers (epoptes)
Related bugs:
  Bug #1428141 in Epoptes: "Clients' local pointer movement can't be grabbed when they get assisted"
  https://bugs.launchpad.net/epoptes/+bug/1428141

For more details, see:
https://code.launchpad.net/~oiteam/epoptes/x11vnc-wrapper-with-alt-input-grabbing/+merge/273703

We're proposing a x11vnc wrapper with an alternative treatment for -grabkbd and -grabptr options.

This is a workaround for a x11vnc -grabptr limitation where only mouse buttons, but not pointer movement, can be grabbed.

It's also a workaround for a x11vnc bug where remote client windows can't be dragged within VNC viewer, if -grabkbd is passed (https://github.com/LibVNC/x11vnc/issues/18).
-- 
Your team Epoptes Developers is requested to review the proposed merge of lp:~oiteam/epoptes/x11vnc-wrapper-with-alt-input-grabbing into lp:epoptes.

=== modified file 'data/client-functions'
--- data/client-functions	2015-08-22 17:30:18 +0000
+++ data/client-functions	2015-10-07 14:43:39 +0000
@@ -222,6 +222,79 @@
     background ./message "$1" "$2" "$3"
 }
 
+# Wraps x11vnc with an alternative treatment
+# for -grabkbd and -grabptr options.
+#
+# This is a workaround for a x11vnc -grabptr limitation
+# where only mouse buttons, but not pointer movement,
+# can be grabbed.
+#
+# It's also a workaround for a x11vnc bug where
+# remote client windows can't be dragged within
+# VNC viewer, if -grabkbd is passed.
+# (https://github.com/LibVNC/x11vnc/issues/18)
+#
+# Parameters:
+# $1..$N = x11vnc arguments.
+x11vnc_wrapper() {
+    local devices=""
+    local args=""
+    local x11vnc_pid=""
+
+    while [ $# -gt 0 ]; do
+        case "$1" in
+            -grabkbd)
+                devices="$devices $(xinput --list | awk '/slave.*keyboard/ {
+                                                        if ($0 !~ /XTEST/) {
+                                                            match($0, /id=[0-9]+/)
+                                                            if (RSTART)
+                                                                print substr($0, RSTART+3, RLENGTH-3)
+                                                            }
+                                                    }')"
+            ;;
+
+            -grabptr)
+                devices="$devices $(xinput --list | awk '/slave.*pointer/ {
+                                                        if ($0 !~ /XTEST/) {
+                                                            match($0, /id=[0-9]+/)
+                                                            if (RSTART)
+                                                                print substr($0, RSTART+3, RLENGTH-3)
+                                                        }
+                                                    }')"
+            ;;
+
+            *)
+                args="$args $1"
+            ;;
+        esac
+
+        shift
+    done
+
+    # Grab input devices
+    for i in $devices; do
+        xinput --set-prop $i "Device Enabled" 0
+    done
+
+    # Just a safety measure to ensure input devices
+    # will be properly ungrabbed if we receive a
+    # SIGTERM or SIGINT while x11vnc is running.
+    #
+    # Uses SIGTERM-propagation scheme as proposed in
+    # http://veithen.github.io/2014/11/16/sigterm-propagation.html
+    trap 'kill -TERM $x11vnc_pid' TERM INT
+    x11vnc $args &
+    x11vnc_pid=$!
+    wait $x11vnc_pid
+    trap - TERM INT
+    wait $x11vnc_pid
+
+    # Ungrab input devices
+    for i in $devices; do
+        xinput --set-prop $i "Device Enabled" 1
+    done
+}
+
 # Connect to the server to be monitored.
 # Parameters:
 # $1 = port.
@@ -234,7 +307,7 @@
 # $1 = port.
 # $2 = grab keyboard and mouse.
 get_assisted() {
-    background x11vnc -noshm -24to32 ${2:+-grabptr -grabkbd} -connect_or_exit "$SERVER:$1"
+    background x11vnc_wrapper -noshm -24to32 ${2:+-grabptr -grabkbd} -connect_or_exit "$SERVER:$1"
 }
 
 # Deactivate the screensaver, in order for the users to watch a broadcast.

=== modified file 'debian/control'
--- debian/control	2015-10-06 19:20:25 +0000
+++ debian/control	2015-10-07 14:43:39 +0000
@@ -32,7 +32,7 @@
 Architecture: all
 Depends: ${python:Depends}, ${misc:Depends}, bsdmainutils,
  iperf, iproute2 | iproute, librsvg2-common, procps, python-gtk2,
- screen, socat, x11vnc, xvnc4viewer | ssvnc | vnc-viewer
+ screen, socat, x11vnc, xvnc4viewer | ssvnc | vnc-viewer, xinput
 Recommends: openssl, xterm
 Suggests: ethtool
 Description: Computer lab management tool (client)