create-cdebootstrap-initrd.sh

#!/bin/sh

set -x

NAME=thingy
MIRROR=ftp.at.debian.org/debian

tmpdir=$(mktemp -p "${TMPDIR:-/tmp/}" -d $NAME-XXXX) || exit 1
#tmpdir=/tmp/thingy
#mkdir -p "$tmpdir"
trap 'rm -r '"$tmpdir" 0 2 15

unpack_deb () {
    (
        p="$PWD"
        cd "$tmpdir"
        ar x "$p/$1"
        tar -C rootdir -xf "data.tar."*
        rm "data.tar."*
    )
}

wget --continue http://snapshot.debian.org/archive/debian/20141116T035859Z/pool/main/c/cdebootstrap/cdebootstrap-static_0.6.4_amd64.deb -O cdebootstrap-static.deb

# only needed for dns resolver libraraies which busybox dlopens at runtime
# aparently busybox can be built statically with those though but then I'd have
# to build them myself :/
wget --continue http://snapshot.debian.org/archive/debian/20150415T034434Z/pool/main/g/glibc/libc6_2.19-18_amd64.deb -O libc.deb

wget --continue http://snapshot.debian.org/archive/debian/20150304T220713Z/pool/main/b/busybox/busybox-static_1.22.0-15_amd64.deb -O busybox-static.deb

wget --continue http://snapshot.debian.org/archive/debian/20150128T222235Z/pool/main/b/bash/bash-static_4.3-12_amd64.deb -O bash-static.deb

wget --continue http://snapshot.debian.org/archive/debian/20150427T040903Z/pool/main/l/linux/linux-image-3.16.0-4-amd64_3.16.7-ckt9-3~deb8u1_amd64.deb -O linux-image.deb

mkdir "$tmpdir/rootdir"

unpack_deb libc.deb
unpack_deb cdebootstrap-static.deb
unpack_deb busybox-static.deb
unpack_deb bash-static.deb
unpack_deb linux-image.deb

(
    set -x
    cd "$tmpdir/rootdir"

    mkdir -p bin
    mkdir -p target
    mkdir -p proc
    mkdir -p sys
    mkdir -p dev
    mkdir -p etc/network
    mkdir -p etc/network/if-up.d
    mkdir -p etc/network/if-down.d
    mkdir -p var/run

    cp bin/bash-static bin/bash

    cp ~/var/build/strace-4.10/strace bin
    cp /etc/services etc

    mkdir -p etc/udhcpc/
    cp usr/share/doc/busybox-static/examples/udhcp/simple.script etc/udhcpc/default.script
    chmod +x etc/udhcpc/default.script

    ./bin/busybox --install bin

    ldconfig -r "$PWD"
    depmod -b "$PWD"

    cat > etc/network/interfaces <<EOF
iface eth0 inet dhcp
EOF
    cat > etc/hosts <<EOF
127.0.0.1	localhost
EOF

    cat > init <<EOF
#!/bin/bash-static
echo "--- --- init --- ---"
mount -t proc  none /proc
mount -t sysfs none /sys

modprobe ata_piix
modprobe sg
modprobe sd_mod

mknod /dev/sda b 8 0

modprobe e1000
ifup eth0

export TERM=linux
/bin/bash-static

#/usr/bin/cdebootstrap-static -vd --allow-unauthenticated wheezy /target http://ftp.at.debian.org/debian
EOF
    chmod +x init

    find . > ../list
    cpio -H newc -o < ../list | gzip > ../initrd.img
);

cp rootdir/boot/vmlinuz-3.16.0-4-amd64 "$p"
cp initrd.img "$p"