#!/bin/bash

proc usage_and_exit {
    echo "Usage: stage1_install_busybox.sh UUID"
    exit 1
}

setglobal ARGC = $Argc

if test $(ARGC) -lt 1 {
    usage_and_exit
}

while test $# -gt 0
{
    match $(1) {
        with --*
            usage_and_exit
            
        with * setglobal UUID = $(1)
            
    }
    shift
}

setglobal BUSYBOX = $(BUSYBOX_BINARY:-$(which busybox 2> /dev/null))

if test ! -x $(BUSYBOX) {
    echo "error: busybox binary is not executable: Install it or set BUSYBOX_BINARY env variable"
    exit 1
}

setglobal IS_STATIC = $[file $(BUSYBOX) | grep static]

if test -z $(IS_STATIC) {
    echo "error: busybox binary is not statically linked"
    exit 1
}

setglobal RKT_RUN_DIR = '"/var/lib/rkt/pods/run'"
setglobal POD_DIR = ""$(RKT_RUN_DIR)/$(UUID)""

setglobal BUSYBOX_LINKS = '"ls cp cat mount vi awk chmod chown mv df ps rm tar top tr wc which ping'"

setglobal NSPAWN_PID = $[ps aux | grep "[u]uid=$UUID" | awk '{print $2}]

sudo nsenter -m -t $(NSPAWN_PID) cp $(BUSYBOX) $(POD_DIR)/stage1/rootfs/bin
sudo nsenter -m -t $(NSPAWN_PID) chmod +x "$(POD_DIR)/stage1/rootfs/bin/busybox"

for link in [$(BUSYBOX_LINKS)] {
    sudo nsenter -m -t $(NSPAWN_PID) ln -sf busybox "$(POD_DIR)/stage1/rootfs/bin/$(link)"
}

echo "Busybox installed. Use the following command to enter pod's stage1:"
setglobal SYSTEMD_PPID = $[sudo cat "$(RKT_RUN_DIR)/$(UUID)/ppid]
setglobal SYSTEMD_PID = $[sudo cat /proc/$SYSTEMD_PPID/task/$SYSTEMD_PPID/children]
echo sudo nsenter -m -u -i -p -t $(SYSTEMD_PID)