[PATCH] utils: Add hardlinkdir shell function

[Richard Purdie <richard.purdie@linuxfoundation.org>]

In a number of places it would be helpful to be able to copy trees of
files using hardlinks. This turns out to be harder than you'd expect
since there is no good single command that does this well and handles
all file types correctly.

Abstracting this into a function therefore makes sense, cpio seems
as good an option as any other. We do require two passes due to the
way cpio handles symbolic links.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/meta/classes/utils.bbclass b/meta/classes/utils.bbclass
index 0a533af..91895ec 100644
--- a/meta/classes/utils.bbclass
+++ b/meta/classes/utils.bbclass
@@ -292,6 +292,17 @@ END
 	chmod +x $cmd
 }
 
+# Copy files/directories from $1 to $2 but using hardlinks
+# Have to do this in two passes to handle symbolic links correctly due to
+# the way cpio handles this combination of options.
+hardlinkdir () {
+	from=$1
+	to=$2
+	(cd $from; find . -print0 | cpio --null -pdlu $to)
+	(cd $from; find . -type l -print0 | cpio -pd0mLu --no-preserve-owner $to)
+}
+
+
 def check_app_exists(app, d):
     app = d.expand(app)
     path = d.getVar('PATH', d, True)