Auto-detect foreign architectures in packagelist.

* Add function to output unique list of foreign architectures from an
  expanded package list.
* If foreign architectures are detected, add unique architectures
  to dpkg and update apt.
* This requires users to explicitly list at least _one_ package of a
  foreign architecture in their package list (e.g. foo:arch) for any other
  foreign arch dependencies to be handled appropriately.

functions/packagelists.sh

@@ -118,3 +118,30 @@ Expand_packagelist ()
 		done
 	done
 }
+
+Discover_package_architectures ()
+{
+	_LB_EXPANDED_PKG_LIST="${1}"
+	_LB_DISCOVERED_ARCHITECTURES=""
+
+	shift
+
+	if [ -e "${_LB_EXPANDED_PKG_LIST}" ] && [ -s "${_LB_EXPANDED_PKG_LIST}" ]
+	then
+		while read _LB_PACKAGE_LINE
+		do
+			# Lines from the expanded package list may have multiple, space-separated packages
+			for _LB_PACKAGE_LINE_PART in ${_LB_PACKAGE_LINE}
+			do
+				# Looking for <package>:<architecture>
+				if [ -n "$(echo ${_LB_PACKAGE_LINE_PART} | awk -F':' '{print $2}')" ]
+				then
+					_LB_DISCOVERED_ARCHITECTURES="${_LB_DISCOVERED_ARCHITECTURES} $(echo ${_LB_PACKAGE_LINE_PART} | awk -F':' '{print $2}')"
+				fi
+			done
+		done < "${_LB_EXPANDED_PKG_LIST}"
+
+		# Output unique architectures, alpha-sorted, one per line
+		echo "${_LB_DISCOVERED_ARCHITECTURES}" | tr -s '[:space:]' '\n' | sort | uniq
+	fi
+}

scripts/build/chroot_install-packages

@@ -42,6 +42,38 @@ Check_lockfile .lock
 # Creating lock file
 Create_lockfile .lock
 
+# Check for packages specified with foreign architecture
+_FOREIGN_ARCHITECTURES_FILE="chroot/root/packages.foreign-architectures"
+if [ -e "${_FOREIGN_ARCHITECTURES_FILE}" ] && [ -s "${_FOREIGN_ARCHITECTURES_FILE}" ]
+then
+	_APT_ARCHITECTURES_ADDED="0"
+
+	# Check if version of dpkg in chroot supports multiarch
+	if Chroot chroot dpkg --print-foreign-architectures > /dev/null 2>&1
+	then
+		# Add foregin architectures
+		while read _ARCHITECTURES_LINE
+		do
+			Echo_message "Adding foreign architecture ${_ARCHITECTURES_LINE} to dpkg"
+			Chroot chroot dpkg --add-architecture ${_ARCHITECTURES_LINE}
+
+			_APT_ARCHITECTURES_ADDED="1"
+		done < "${_FOREIGN_ARCHITECTURES_FILE}"
+
+		# Tidy up
+		rm -f "${_FOREIGN_ARCHITECTURES_FILE}"
+	else
+		Echo_error "Version of dpkg in chroot does not support foreign architectures."
+	fi
+
+	# Update apt if foreign architectures were added
+	if [ "${_APT_ARCHITECTURES_ADDED}" -ne "0" ]
+	then
+		Echo_message "Added foreign architectures, updating apt..."
+		Apt chroot update
+	fi
+fi
+
 if [ -e chroot/root/packages.chroot ] && [ -s chroot/root/packages.chroot ]
 then
 	# Restoring cache

scripts/build/chroot_package-lists

@@ -89,6 +89,17 @@ do
 	fi
 done
 
+# Discover unique package architectures in fully-expanded package list
+for _PACKAGE_ARCHITECTURE in $(Discover_package_architectures "chroot/root/packages.chroot")
+do
+	# If this is a foreign architecture, append to packages.foreign-architectures
+	if [ "${_PACKAGE_ARCHITECTURE}" != "${LIVE_IMAGE_ARCHITECTURE}" ]
+	then
+		Echo_message "Accepting foreign architecture: ${_PACKAGE_ARCHITECTURE}, live image architecture is: ${LIVE_IMAGE_ARCHITECTURE}"
+		echo "${_PACKAGE_ARCHITECTURE}" >> chroot/root/packages.foreign-architectures
+	fi
+done
+
 rm -f chroot/bin/Packages
 
 case "${LB_BUILD_WITH_CHROOT}" in