[PATCH] kheaders: substituting --sort in archive creation

[Dmitry Goldin]

From: Dmitry Goldin <dgoldin+lkml@xxxxxxxxxxxxx>

The option --sort=ORDER was only introduced in tar 1.28 (2014), which
is rather new and might not be available in some setups.

This patch tries to replicate the previous behaviour as closely as possible
to fix the kheaders build for older environments. It does not produce identical
archives compared to the previous version due to minor sorting
differences but produces reproducible results itself in my tests.

Signed-off-by: Dmitry Goldin <dgoldin+lkml@xxxxxxxxxxxxx>
---
 kernel/gen_kheaders.sh | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh
index aff79e461fc9..5a0fc0b0403a 100755
--- a/kernel/gen_kheaders.sh
+++ b/kernel/gen_kheaders.sh
@@ -71,10 +71,13 @@ done | cpio --quiet -pd $cpio_dir >/dev/null 2>&1
 find $cpio_dir -type f -print0 |
 	xargs -0 -P8 -n1 perl -pi -e 'BEGIN {undef $/;}; s/\/\*((?!SPDX).)*?\*\///smg;'

-# Create archive and try to normalize metadata for reproducibility
-tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \
-    --owner=0 --group=0 --sort=name --numeric-owner \
-    -Jcf $tarfile -C $cpio_dir/ . > /dev/null
+# Create archive and try to normalize metadata for reproducibility.
+# For compatibility with older versions of tar, files are fed to tar
+# pre-sorted, as --sort=name might not be available.
+find $cpio_dir -printf "./%P\n" | LC_ALL=C sort | \
+    tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \
+    --owner=0 --group=0 --numeric-owner --no-recursion \
+    -Jcf $tarfile -C $cpio_dir/ -T - > /dev/null

 echo "$src_files_md5" >  kernel/kheaders.md5
 echo "$obj_files_md5" >> kernel/kheaders.md5
--
2.23.0