rtcds CLI add check for /usr/src/linux

The RCG expects the kernel source at /usr/src/linux.  This is not
installed by default and has to be created manually, unfortunately.
Until this is fixed in the RCG we add a check for it here.

git-svn-id: https://redoubt.ligo-wa.caltech.edu/svn/advLigoRTS/trunk@4514 6dcd42c9-f523-4c6d-aada-af552506706e

support/bin/rtcds.in

@@ -51,6 +51,46 @@ check_env() {
     done
 }
 
+# FIXME: the RCG currently requires that the kernel source be at
+# /usr/src/linux.  this checks that /usr/src/linux is a symlink to the
+# header dir for the currently running kernel.  This shouldn't be
+# necessary once the RCG is fixed.
+check_linux_src() {
+    if [ "$RCG_IGNORE_KERNEL_RELEASE" ] ; then
+	return
+    fi
+    local target=$(readlink /usr/src/linux)
+    local msg=
+    if [ ! -d /usr/src/linux ] ; then
+	msg="Missing linux source."
+    elif [ -z "$target" ] ; then
+	msg="Unknown linux source."
+    fi
+    local release=$(uname -r | sed 's/-amd64$/-common/')
+    for ls in /usr/src/linux-headers-${release}{,-common} ; do
+	if [[ "$target" == "$ls" ]] ; then
+	    return
+	fi
+	if [ -d "$ls" ] ; then
+	    break
+	fi
+    done
+    if [ -z "$msg" ] ; then
+	msg="Linux source does not match currently running kernel."
+    fi
+    log "$msg
+
+The RCG expects the linux source to be at /usr/src/linux.  For modern
+distros this should be a symlink to the source installed as part of
+the kernel header package for the running kernel.  For this system:
+
+/usr/src/linux -> $ls
+
+Please create this link, or set the RCG_IGNORE_KERNEL_RELEASE
+environment variable to bypass this check."
+    exit 10
+}
+
 prep_target(){
     log "creating OPTRTCDS..."
     mkdir -p ${OPTRTCDS}/{target,chans}/tmp
@@ -233,6 +273,7 @@ case $cmd in
 	    log "You must specify at least one system to build."
 	    exit 2
 	fi
+	check_linux_src
 	check_env
 	prep_buildd
 	build_sys $@