can generate initramfs from busybox

Signed-off-by: Nico Schottelius <nico@wurzel.schottelius.org>

hacking/add_kernel_isolinux.sh

@@ -1,29 +0,0 @@
-#!/bin/sh
-
-# FIXME: Write cdist type / explorer that finds
-# package for a file, distro independent
-
-if [ "$#" -ne 1 ]; then
-    echo "$0 dir-out"
-    exit 1
-fi
-
-dir=$1; shift
-boot=$dir/boot
-
-mkdir -p "$boot"
-cp /boot/vmlinuz-linux                      \
-    /boot/initramfs-linux-fallback.img      \
-    /usr/lib/syslinux/bios/isolinux.bin     \
-    "$boot"
-
-cp /usr/lib/syslinux/bios/ldlinux.c32      \
-    "$dir"
-
-cat > "$dir/isolinux.cfg" << eof
-default preos
-label   preos
-title   cdist PreOS
-linux   /boot/vmlinuz-linux
-initrd  /boot/initramfs-linux-fallback.img
-eof

hacking/v3-busybox/add_kernel_isolinux.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+# FIXME: distro specific kernel location
+
+if [ "$#" -ne 1 ]; then
+    echo "$0 dir-out"
+    exit 1
+fi
+
+dir=$1; shift
+boot=$dir/boot
+
+mkdir -p "$boot"
+cp /boot/vmlinuz-linux "$boot/linux"
+cp /usr/lib/syslinux/bios/isolinux.bin "$boot"
+cp /usr/lib/syslinux/bios/ldlinux.c32 "$dir"
+
+cat > "$dir/isolinux.cfg" << eof
+default preos
+label   preos
+title   cdist PreOS
+linux   /boot/linux
+initrd  /boot/initramfs
+eof

hacking/v3-busybox/all.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+rm -rf preos
+mkdir -p preos/boot
+
+./generate.sh > preos/boot/initramfs
+./add_kernel_isolinux.sh preos
+

hacking/v3-busybox/generate.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+set -ex
+
+
+initramfs_dir=$(mktemp -d /tmp/cdist-preos.XXXXXXX)
+# initramfs_dir=$1
+
+for dir in bin sbin etc proc sys newroot; do
+    mkdir -p ${initramfs_dir}/$dir
+done
+touch ${initramfs_dir}/etc/mdev.conf
+
+cp init "${initramfs_dir}/init"
+cp $(which busybox) "${initramfs_dir}/bin"
+ln -fs busybox "${initramfs_dir}/bin/sh"
+
+cd "${initramfs_dir}"
+find . | cpio -H newc -o | gzip
+
+exit 0
+
+# TODO:
+# - Kernel modules
+# - ssh
+# - various mkfs
+# - libs
+

hacking/v3-busybox/init

@@ -0,0 +1,60 @@
+#!/bin/sh
+
+#Mount things needed by this script
+mount -t proc proc /proc
+mount -t sysfs sysfs /sys
+
+#Disable kernel messages from popping onto the screen
+echo 0 > /proc/sys/kernel/printk
+
+#Create all the symlinks to /bin/busybox
+busybox --install -s
+
+#Create device nodes
+mknod /dev/null c 1 3
+mknod /dev/tty c 5 0
+mdev -s
+
+#Function for parsing command line options with "=" in them
+# get_opt("init=/sbin/init") will return "/sbin/init"
+get_opt() {
+    echo "$@" | cut -d "=" -f 2
+}
+
+#Defaults
+init="/sbin/init"
+root="/dev/hda1"
+
+#Process command line options
+for i in $(cat /proc/cmdline); do
+    case $i in
+        root\=*)
+            root=$(get_opt $i)
+            ;;
+        init\=*)
+            init=$(get_opt $i)
+            ;;
+    esac
+done
+
+
+exec sh
+
+# Skipping the rest
+
+#Mount the root device
+mount "${root}" /newroot
+
+#Check if $init exists and is executable
+if [[ -x "/newroot/${init}" ]] ; then
+    #Unmount all other mounts so that the ram used by
+    #the initramfs can be cleared after switch_root
+    umount /sys /proc
+    
+    #Switch to the new root and execute init
+    exec switch_root /newroot "${init}"
+fi
+
+#This will only be run if the exec above failed
+echo "Failed to switch_root, dropping to a shell"
+exec sh