In the original multibuild.eclass code I tried to somehow achieve very
fast merging via avoiding actually copying anything. I used the 'cp -al'
call that used hardlinks to avoid copying data but that actually made
copying non-clobbering and less portable (BSD used a tar fallback, for
example, due to some bugs at the time).
While the original solution worked and was quite good for its initial
use, the fact that it is non-clobbering is a bit confusing and resulted
in late breakage in llvm ebuild (where I assumed it will clobber). I
think it's time to replace it with something simpler, more portable (no
more userland checks) and fully clobbering.
For this reason, the patch replaces the old code with a plain 'cp -PpR'
that should be POSIX-compliant. It also tries to use '--reflink=auto' if
available to make use of btrfs CoW support.
I'd appreciate very much of someone could put the code into thorough
testing. The consumers include all distutils-r1 ebuilds, multilib
ebuilds, PyQt4 and the reverted version of llvm :).
---
eclass/multibuild.eclass | 24 ++++++++----------------
1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/eclass/multibuild.eclass b/eclass/multibuild.eclass
index 0a2771e..e3e5e21 100644
--- a/eclass/multibuild.eclass
+++ b/eclass/multibuild.eclass
@@ -265,24 +265,16 @@ multibuild_merge_root() {
done
rm "${lockfile_l}" || die
- if use userland_BSD; then
- # 'cp -a -n' is broken:
- # http://www.freebsd.org/cgi/query-pr.cgi?pr=174489
- # using tar instead which is universal but terribly slow.
-
- tar -C "${src}" -f - -c . \
- | tar -x -f - -C "${dest}"
- [[ ${PIPESTATUS[*]} == '0 0' ]]
- ret=${?}
- elif use userland_GNU; then
- # cp works with '-a -n'.
-
- cp -a -l -n "${src}"/. "${dest}"/
- ret=${?}
- else
- die "Unsupported userland (${USERLAND}), please report."
+ local cp_args=()
+
+ if cp --reflink=auto --version &>/dev/null; then
+ # enable reflinking if possible to make this faster
+ cp_args+=( --reflink=auto )
fi
+ cp -P -R -p "${cp_args[@]}" "${src}"/. "${dest}"/
+ ret=${?}
+
# Remove the lock.
rm "${lockfile}" || die
--
1.9.1
