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nixpkgs/pkgs/build-support/kernel/make-initrd.sh
Joachim Fasting 5a8147479e make-initrd: create reproducible initrds
To achieve reproducible results, `cpio` archive members are added in
sorted order and inodes renumbered.

The `cpio-clean.pl` script is made obsolete by setting mtimes via
`touch` & using `cpio --reproducible`.  Suggested by @dezgeg in
https://github.com/NixOS/nixpkgs/pull/21273#issuecomment-268116605.

Note that using `--reproducible` means that initial ramdisk creation now
requires at least `cpio` version 2.12 (released in 2015).
2016-12-20 14:00:04 +01:00

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source $stdenv/setup
set -o pipefail
objects=($objects)
symlinks=($symlinks)
suffices=($suffices)
mkdir root
# Needed for splash_helper, which gets run before init.
mkdir root/dev
mkdir root/sys
mkdir root/proc
for ((n = 0; n < ${#objects[*]}; n++)); do
object=${objects[$n]}
symlink=${symlinks[$n]}
suffix=${suffices[$n]}
if test "$suffix" = none; then suffix=; fi
mkdir -p $(dirname root/$symlink)
ln -s $object$suffix root/$symlink
done
# Get the paths in the closure of `object'.
storePaths=$(perl $pathsFromGraph closure-*)
# Paths in cpio archives *must* be relative, otherwise the kernel
# won't unpack 'em.
(cd root && cp -prd --parents $storePaths .)
# Put the closure in a gzipped cpio archive.
mkdir -p $out
for PREP in $prepend; do
cat $PREP >> $out/initrd
done
(cd root && find * -print0 | xargs -0r touch -h -d '@1')
(cd root && find * -print0 | sort -z | cpio -o -H newc -R +0:+0 --reproducible --null | $compressor >> $out/initrd)
if [ -n "$makeUInitrd" ]; then
mv $out/initrd $out/initrd.gz
mkimage -A arm -O linux -T ramdisk -C gzip -d $out/initrd.gz $out/initrd
fi