[v2,2/2] fs/cpio: make cpio rootfs reproducible
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Message ID 20190716173518.11081-2-itsatharva@gmail.com
State Accepted
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Series
  • [v2,1/2] package/cpio: add host version
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Commit Message

Atharva Lele July 16, 2019, 5:35 p.m. UTC
Pass the recommended argument in the CPIO manual to make cpio archives
reproducible.

Reference: https://www.gnu.org/software/cpio/manual/cpio.html#Copy_002dpass-mode

Pre-patch diffoscope output: https://gitlab.com/snippets/1874745
Post-patch: https://gitlab.com/snippets/1874746

We can see that post-patch, the archive related differences are removed.
The differences are arising from utils/bin/getconf. This will have to
be investigated further. However, that is unrelated to cpio.

Signed-off-by: Atharva Lele <itsatharva@gmail.com>
Reviewed-by: Yann E. MORIN <yann.morin.1998@free.fr>
---
Changes v1 -> v2:
  - Added comment
  - Build host-cpio if we are reproducible, reason is --reproducible
    option does not exist prior to cpio 2.12. (suggested by Yann, Arnout)
  - Changed pure assignment to append-assignment
  - CPIO_OPTS -> ROOTFS_CPIO_OPTS to prevent clash with cpio package's options
    if added in future
---
 fs/cpio/cpio.mk | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

Comments

Thomas Petazzoni July 17, 2019, 6:56 a.m. UTC | #1
Hello,

On Tue, 16 Jul 2019 23:05:18 +0530
Atharva Lele <itsatharva@gmail.com> wrote:

> +# --repoducible option was not introduced until cpio v2.12. Some distros

The kind of double negation here "was not introduced until" looked a
bit complicated compared to just "--reproducible was introduced in cpio
v2.12". I've simplified the paragraph to:

+# --repoducible option was introduced in cpio v2.12, which may not be
+# available in some old distributions, so we build host-cpio

And of course now I notice that --repoducible has a typo, and should be
--reproducible. Oh well.

> +# like Ubuntu 16.04 or Debian oldstable which package v2.11. Hence build
> +# host-cpio.
> +ifeq ($(BR2_REPRODUCIBLE), y)

No space after comma. I fixed that up.

Applied with those changes. Thanks!

Thomas

Patch
diff mbox series

diff --git a/fs/cpio/cpio.mk b/fs/cpio/cpio.mk
index 1f0cafe62f..275064d9cb 100644
--- a/fs/cpio/cpio.mk
+++ b/fs/cpio/cpio.mk
@@ -29,8 +29,16 @@  endif # BR2_ROOTFS_DEVICE_CREATION_STATIC
 
 ROOTFS_CPIO_PRE_GEN_HOOKS += ROOTFS_CPIO_ADD_INIT
 
+# --repoducible option was not introduced until cpio v2.12. Some distros
+# like Ubuntu 16.04 or Debian oldstable which package v2.11. Hence build
+# host-cpio.
+ifeq ($(BR2_REPRODUCIBLE), y)
+ROOTFS_CPIO_DEPENDENCIES += host-cpio
+ROOTFS_CPIO_OPTS += --reproducible
+endif
+
 define ROOTFS_CPIO_CMD
-	cd $(TARGET_DIR) && find . | cpio --quiet -o -H newc > $@
+	cd $(TARGET_DIR) && find . | cpio $(ROOTFS_CPIO_OPTS) --quiet -o -H newc > $@
 endef
 
 ifeq ($(BR2_TARGET_ROOTFS_CPIO_UIMAGE),y)