From 79c4b61f2283b699978ee74df79eddd1ca289acf Mon Sep 17 00:00:00 2001
From: don bright <hugh.m.bright@gmail.com>
Date: Sat, 16 Feb 2013 15:38:11 +0100
Subject: [PATCH] deal with some unusual systems where $! doesn't work as
 expected

---
 tests/virtualfb.sh | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/tests/virtualfb.sh b/tests/virtualfb.sh
index 5abd804d..06d37bf4 100755
--- a/tests/virtualfb.sh
+++ b/tests/virtualfb.sh
@@ -3,6 +3,8 @@
 # Toggle the Virtual Framebuffer
 # If started, stop. If stopped, start.
 
+debug=
+
 start()
 {
   if [ "`command -v Xvfb`" ]; then
@@ -20,7 +22,20 @@ start()
 
   VFB_DISPLAY=`echo | awk 'BEGIN{srand();} {printf ":%.0f", rand()*1000+100};'`
   $VFB_BINARY $VFB_DISPLAY -screen 0 800x600x24 &> ./virtualfb.log &
-  VFB_PID=$!
+  # on some systems $! gives us VFB_BINARY's PID, on others we have to subtract 1
+  VFB_PID_MINUS0=$!
+  VFB_PID_MINUS1=$(($VFB_PID_MINUS0 - 1))
+
+  if [ "`ps cax | grep $VFB_PID_MINUS0 | grep $VFB_BINARY`" ]; then
+    VFB_PID=$VFB_PID_MINUS0
+  elif [ "`ps cax | grep $VFB_PID_MINUS1 | grep $VFB_BINARY`" ]; then
+    VFB_PID=$VFB_PID_MINUS1
+  else
+    echo started $VFB_BINARY but cannot find process ID in process table
+    echo please stop $VFB_BINARY manually
+    VFB_PID=
+    return
+  fi
 
   echo $VFB_DISPLAY > ./virtualfb.DISPLAY
   echo $VFB_PID > ./virtualfb.PID
@@ -48,13 +63,29 @@ isrunning()
 {
   isrunning_result=
   if [ -e ./virtualfb.PID ]; then
+    if [ $debug ]; then echo "found PID file"; fi
     VFB_PID=`cat ./virtualfb.PID`
+    if [ ! $VFB_PID ]; then
+      echo ./virtualfb.PID contained invalid PID number
+      return
+    fi
+    if [ $debug ]; then echo "PID from file:" $VFB_PID; fi
+    PS_RESULT=`ps cax | awk ' { print $1 } '`
+    GREP_RESULT=`echo $PS_RESULT | grep $VFB_PID`
+    if [ $debug ]; then echo "grep ps result: " $GREP_RESULT; fi
     if [ "`ps cax | awk ' { print $1 } ' | grep ^$VFB_PID\$`" ]; then
+      if [ $debug ]; then echo "found pid in process table."; fi
       isrunning_result=1
+    else
+      if [ $debug ]; then echo "did not find pid in process table."; fi
     fi
   fi
 }
 
+if [ "`echo $* | grep debug`" ]; then
+  debug=1
+fi
+
 isrunning
 if [ $isrunning_result ]; then
   stop