board_options: new portageq wrappers

- May be sourced early, so explicitly die if source fails.
 - Add a function for getting the latest version of a package.
 - Read PROVIDES metadata using portageq, enabling data to be read from
   binary packages in addition to installed packages. The performance
   issue is not an issue here and needed to support empty build roots.

build_library/board_options.sh

@@ -12,7 +12,7 @@ BOARD_ROOT="/build/${BOARD}"
 ARCH=$(get_board_arch ${BOARD})
 
 # What cross-build are we targeting?
-. "${BOARD_ROOT}/etc/portage/make.conf"
+. "${BOARD_ROOT}/etc/portage/make.conf" || die
 
 # check if any of the given use flags are enabled for a pkg
 pkg_use_enabled() {
@@ -25,12 +25,18 @@ pkg_use_enabled() {
   return $?
 }
 
-# get a package's SONAMEs in soname.provided format
-pkg_soname_provides() {
+# Usage: pkg_version [installed|binary|ebuild] some-pkg/name
+# Prints: some-pkg/name-1.2.3
+# Note: returns 0 even if the package was not found.
+pkg_version() {
+  portageq-"${BOARD}" best_visible "${BOARD_ROOT}" "$1" "$2"
+}
+
+# Usage: pkg_provides [installed|binary] some-pkg/name-1.2.3
+# Prints: x86_32: libfoo.so.2 x86_64: libfoo.so.2
+pkg_provides() {
   local provides p
-  # We could run this command but it ugly and silly slow:
-  # portageq-"${BOARD}" metadata "${BOARD_ROOT}" installed "$1" PROVIDES
-  provides=$(<"${BOARD_ROOT}/var/db/pkg/$1/PROVIDES")
+  provides=$(portageq-"${BOARD}" metadata "${BOARD_ROOT}" "$1" "$2" PROVIDES)
 
   if [[ -z "$provides" ]]; then
     return

build_library/build_image_util.sh

@@ -211,7 +211,7 @@ package_provided() {
     for p in "$@"; do
         info "Writing $p to package.provided and soname.provided"
         echo "$p" >> "${profile}/package.provided"
-	pkg_soname_provides "$p" >> "${profile}/soname.provided"
+	pkg_provides binary "$p" >> "${profile}/soname.provided"
     done
 }