Support simple conditionals in package lists

This patch adds support for simple conditionals in package lists. For
example, to limit a package to i386 only:

 foo
 #if ARCHITECTURE i386
 package-only-in-i386
 #endif
 bar

Any variable that beings in LH_ can be expanded:

 #if MODE ubuntu
 package-only-in-ubuntu
 #endif

Nesting of conditionals is not supported. If the variable to be expanded
does not exist, the conditional is false.

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>

functions/packageslists.sh

@@ -20,6 +20,8 @@ Expand_packagelist ()
 		_LH_LIST_NAME="$(echo ${_LH_EXPAND_QUEUE} | cut -d" " -f1)"
 		_LH_EXPAND_QUEUE="$(echo ${_LH_EXPAND_QUEUE} | cut -s -d" " -f2-)"
 		_LH_LIST_LOCATION=""
+		_LH_NESTED=0
+		_LH_ENABLED=1
 
 		for _LH_SEARCH_PATH in ${@} "${LH_BASE:-/usr/share/live-helper}/lists"
 		do
@@ -35,17 +37,55 @@ Expand_packagelist ()
 			continue
 		fi
 
-		# Output packages
+		while read _LH_LINE
-		grep -v "^#" ${_LH_LIST_LOCATION} | grep .
+		do
+			case "${_LH_LINE}" in
+				\#if\ *)
+					if [ ${_LH_NESTED} -eq 1 ]
+					then
+						echo "E: Nesting conditionals is not supported" >&2
+						exit 1
+					fi
 
-		# Find includes
+					_LH_NESTED=1
-		_LH_INCLUDES="$(sed -n \
+					_LH_VAR="$(echo "${_LH_LINE}" | cut -d' ' -f2)"
-			-e 's|^#<include> \([^ ]*\)|\1|gp' \
+					_LH_VAL="$(echo "${_LH_LINE}" | cut -d' ' -f3)"
-			-e 's|^#include <\([^ ]*\)>|\1|gp' \
-			"${_LH_LIST_LOCATION}")"
 
-		# Add to queue
+					if [ -n "${_LH_VAR}" ] && [ "$(eval "echo \$LH_${_LH_VAR}")" != "${_LH_VAL}" ]
-		_LH_EXPAND_QUEUE="$(echo ${_LH_EXPAND_QUEUE} ${_LH_INCLUDES} | \
+					then
-			sed -e 's|[ ]*$||' -e 's|^[ ]*||')"
+						_LH_ENABLED=0
+					fi
+					;;
+
+				\#endif*)
+					_LH_NESTED=0
+					_LH_ENABLED=1
+					;;
+
+				\#*)
+					if [ ${_LH_ENABLED} -ne 1 ]
+					then
+						continue
+					fi
+
+					# Find includes
+					_LH_INCLUDES="$(echo "${_LH_LINE}" | sed -n \
+						-e 's|^#<include> \([^ ]*\)|\1|gp' \
+						-e 's|^#include <\([^ ]*\)>|\1|gp')"
+
+					# Add to queue
+					_LH_EXPAND_QUEUE="$(echo ${_LH_EXPAND_QUEUE} ${_LH_INCLUDES} |
+						sed -e 's|[ ]*$||' -e 's|^[ ]*||')"
+					;;
+
+				*)
+					if [ ${_LH_ENABLED} -eq 1 ]
+					then
+						echo "${_LH_LINE}"
+					fi
+					;;
+
+			esac
+		done < "${_LH_LIST_LOCATION}"
 	done
 }