classes/buildhistory: fix error when no packages are installed

"xargs -n1 basename" will execute basename even if there are no lines
piped into it, causing a "basename: missing operand" error if no
packages are installed, which will happen for the target portion of
buildtools-tarball.

(xargs' -r option could have been used here, but it is a GNU extension
and I thought it best to avoid that for the sake of future
interoperability).

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/classes/buildhistory.bbclass b/meta/classes/buildhistory.bbclass
index c8fd68c39e0060c9f467abd2d13faa126619deb1..36e7fe13be2e22fe6d2989653a83a2ca9809b970 100644 (file)
--- a/meta/classes/buildhistory.bbclass
+++ b/meta/classes/buildhistory.bbclass
@@ -319,7 +319,11 @@ buildhistory_get_installed() {
        list_installed_packages file | sort > $pkgcache
 
        cat $pkgcache | awk '{ print $1 }' > $1/installed-package-names.txt
-       cat $pkgcache | awk '{ print $2 }' | xargs -n1 basename > $1/installed-packages.txt
+       if [ -s $pkgcache ] ; then
+               cat $pkgcache | awk '{ print $2 }' | xargs -n1 basename > $1/installed-packages.txt
+       else
+               printf "" > $1/installed-packages.txt
+       fi
 
        # Produce dependency graph
        # First, filter out characters that cause issues for dot