Mac: new screensaver helper shell script

clientscr/boinc_ss_helper.sh

@@ -0,0 +1,72 @@
+# This file is part of BOINC.
+# http:#boinc.berkeley.edu
+# Copyright (C) 2020 University of California
+#
+# BOINC is free software; you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License
+# as published by the Free Software Foundation,
+# either version 3 of the License, or (at your option) any later version.
+#
+# BOINC is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with BOINC.  If not, see <http:#www.gnu.org/licenses/>.
+#
+#  boinc_ss_helper.sh
+#
+# Used under OS 10.15 Catalina and later to launch screensaver graphics apps
+#
+# BOINC screensaver plugin BOINCSaver.saver (BOINC Screensaver Coordinator)
+# sends a run_graphics_app RPC to the BOINC client. The BOINC client then 
+# launches switcher, which submits this script to launchd as a LaunchAgent
+# for the user that invoked the screensaver (the currently logged in user.)
+# This script then launches gfx_switcher, which uses fork and execv to 
+# launch the project graphics app. gfx_switcher writes the graphics app's 
+# process ID to shared memory, to be read by the Screensaver Coordinator. 
+# gfx_switcher waits for the graphics app to exit and notifies then notifies 
+# the Screensaver Coordinator by writing 0 to the shared memory.
+#
+# We must go through launchd to establish a connection to the windowserver 
+# in the currently logged in user's space for use by the project graphics
+# app. This script then launches gfx_switcher, which uses execv to launch 
+# the project graphics app.
+# This Rube Goldberg process is necessary due to limitations on screensavers
+# introduced in OS 10.15 Catalina.
+
+#!/bin/sh
+
+# argv[0] = path to this script
+# argv[1] = directory
+# argv[2] = branded screensaver name
+# argv[3] = command for gfx_switcher: -default_gfx, -launch_gfx or -kill_gfx
+# argv[4] = "boincscr", slot # or pid
+# argv[5] = --fullscreen (not used for -kill_gfx)
+# argv[6] = --ScreensaverLoginUser (not used for -kill_gfx)
+# argv[7] = login user name (not used for -kill_gfx)
+
+## For testing only:
+## echo "number of args after argv[0] = $#" >> /Users/Shared/boinc_helper_script.txt
+## echo "arg[1] = $1" >> /Users/Shared/boinc_helper_script.txt
+## echo "arg[2] = $2" >> /Users/Shared/boinc_helper_script.txt
+## echo "arg[3] = $3" >> /Users/Shared/boinc_helper_script.txt
+## echo "arg[4] = $4" >> /Users/Shared/boinc_helper_script.txt
+## if [ $# -eq 7 ]; then   ## bash does not count argv[0] in $#
+## echo "arg[5] = $5" >> /Users/Shared/boinc_helper_script.txt
+## echo "arg[6] = $6" >> /Users/Shared/boinc_helper_script.txt
+## echo "arg[7] = $7" >> /Users/Shared/boinc_helper_script.txt
+## fi
+
+cd "$1"
+pwd
+if [ $# -eq 7 ]; then   ## bash does not count argv[0] in $#
+"/Library/Screen Savers/$2.saver/Contents/Resources/gfx_switcher" $3 $4 $5 $6 $7
+else
+"/Library/Screen Savers/$2.saver/Contents/Resources/gfx_switcher" $3 $4
+fi
+
+# A new submit of edu.berkeley.boinc-ss_helper will be ignored if for some reason 
+# edu.berkeley.boinc-ss_helper is still loaded, so ensure it is removed.
+launchctl remove edu.berkeley.boinc-ss_helper