Add "Removing libbb from opkg" to wiki.

1 files changed, 49 insertions, 0 deletions

diff --git a/dev/todo/removing-libbb-from-opkg.mdwn b/dev/todo/removing-libbb-from-opkg.mdwn
new file mode 100644
index 0000000..2417261
--- /dev/null
+++ b/dev/todo/removing-libbb-from-opkg.mdwn
@@ -0,0 +1,49 @@
+[[!meta title="Removing libbb from opkg"]]
+
+opkg includes and is statically linked with [a copy of libbb][opkg-libbb],
+BusyBox's helper library.  Of course, BusyBox is also linked against its own
+copy of libbb.  This is a bad idea in general, since duplicated code makes
+maintenance more difficult and is often subject to bit rot (resulting in
+long-standing bugs and security problems).  It's an even larger problem (no pun
+intended) in embedded systems, where saving space is important.
+
+The Good News
+-------------
+
+libbb can be built as a shared library by setting the `CONFIG_BUILD_LIBBUSYBOX`
+option to `y` in BusyBox's configuration.  So, we can make `libbusybox.N` and
+`libbusybox.N-dev` binary packages that provide this shared library and its
+header files, modify opkg to dynamically link against this library (instead of
+statically linking against its own copy), and add dependency information to the
+`opkg` source package and its binary packages.
+
+The Bad News
+------------
+
+The copy of libbb in opkg hasn't been updated from its upstream source since at
+least 2008, when opkg development began from the old ipkg sources.  Three months
+later, [an attempt][opkg-devel-libbb] was made by Koen Kooi to update the copy
+of libbb, but it was determined that BusyBox had changed significantly since the
+code was added to ipkg.  Things have most likely gotten much worse in the more
+than three years since then.
+
+To make matters slightly worse, many of the libbb files have been patched in
+opkg.  Any files in [/trunk/libbb][opkg-libbb] newer than revision 3 have opkg
+modifications.
+
+The Plan
+--------
+
+  * Build a shared libbusybox library and set of binary packages.
+  * Port opkg to work with more recent versions of BusyBox's shared library.
+  * Modify opkg to dynamically link against libbusybox.
+  * Add `Build-Depends` and `Depends` fields to the `opkg` source package.
+  * Investigate API and ABI stability of libbusybox.  This may require
+    coordination with BusyBox developers.
+  * Look at each patch in opkg against libbb.  If it's still useful in newer
+    versions, then refresh it, apply it to the `busybox` source package, and
+    forward it upstream to BusyBox.
+
+
+[opkg-libbb]: https://code.google.com/p/opkg/source/browse/trunk/libbb
+[opkg-devel-libbb]: https://groups.google.com/group/opkg-devel/browse_thread/thread/fe5c620bc339ba63