unpack

#!/usr/bin/env bash

err() {
    echo $* >&2
}

abs() {
    echo "$(cd "$(dirname "$1")"; pwd)/$(basename "$1")"
}

if test $# -ne 3
then
    err "usage: $0 <target path> <tarball file> <dependencies file>"
    exit 1
fi

targetPath=$(abs $1)
tarball=$(abs $2)
dependencies=$(abs $3)

fromPrefix=/nix/store
nixrewrite=$(pwd)/nixrewrite

if test ${#targetPath} -gt ${#fromPrefix}
then
    err "error: the new prefix must have at most the same length as \"$fromPrefix\"."
    exit 1
fi

############ TAR (doesn't work)
# mkdir -p $targetPath
# ./nixrewrite $fromPrefix $targetPath $dependencies < $tarball | tar -xC $targetPath

############ CPIO
mkdir -p $targetPath
(cd $targetPath && $nixrewrite $fromPrefix $targetPath $dependencies < $tarball | cpio -id)

############ NAR
# ./nixrewrite $fromPrefix $targetPath $dependencies < $tarball | nix-store --restore $targetPath