cros-workon: extend show_workon_ebuilds to give full paths, provide wrappers

This will allow replacement of equery which in cros-workon

Also other ebuild-related operations like grouping workon ebuilds with the same repo

* Find for all ebuilds takes almost no time when cached and up to ~2 secs when not
* equery takes ages just to load

TEST=cros_workon_ebuilds before and after, and diff:
--- list1       2010-07-27 21:22:23.000000000 -0700
+++ list2       2010-07-27 21:22:32.000000000 -0700
@@ -1,6 +1,5 @@
 app-crypt/tpm-emulator
 app-crypt/trousers
-app-i18n/ibus
 app-i18n/ibus-chewing
 app-i18n/ibus-hangul
 app-i18n/ibus-m17n
(ibus is a mistake, not a workon package, i'll fix that in a separate CL)

	modified:   lib/cros_workon_common.sh

Review URL: http://codereview.chromium.org/2808072

lib/cros_workon_common.sh

@@ -6,16 +6,29 @@
 
 # Common library for functions used by workon tools.
 
-show_workon_ebuilds() {
+find_workon_ebuilds() {
   pushd "${BOARD_DIR}"/etc/ 1> /dev/null
   source make.conf
   popd 1> /dev/null
   local CROS_OVERLAYS="${PORTDIR_OVERLAY}"
 
+  # NOTE: overlay may be a symlink, and we have to use ${overlay}/
   for overlay in ${CROS_OVERLAYS}; do
-    pushd ${overlay} 1> /dev/null
-    find . -name '*.ebuild' | xargs fgrep cros-workon | \
-      awk -F / '{ print $2 "/" $3 }' | uniq | sort
-    popd 1> /dev/null
+    # only look up ebuilds named 9999 to eliminate duplicates
+    find ${overlay}/ -name '*9999.ebuild' | xargs fgrep cros-workon | \
+      sed -e 's/\([.]ebuild\):.*/\1/'|uniq
   done
 }
+
+# wrapper script that caches the result of find_workon_ebuilds()
+show_workon_ebuilds_files() {
+  if [ -z "${CROS_ALL_EBUILDS}" ]; then
+    CROS_ALL_EBUILDS=$(find_workon_ebuilds)
+  fi
+  echo "${CROS_ALL_EBUILDS}"
+}
+
+show_workon_ebuilds() {
+  show_workon_ebuilds_sources | \
+    sed -e 's/.*\/\([^/]*\)\/\([^/]*\)\/.*\.ebuild/\1\/\2/'| sort
+}