#!/usr/bin/env bash
# Regenerate ports/busybox/busybox.config: busybox's own `make defconfig`
# (almost every applet on), minus the applets listed below that cannot work
# on Rustbelt. You only need this when moving to a new busybox version or
# changing the list; the build uses the committed busybox.config as is.
#
# Usage: ports/busybox/mkconfig.sh CACHE_DIR WORK_DIR
#   (WORK_DIR gets an unpacked busybox; the result is written back to
#    ports/busybox/busybox.config, so check `git diff` afterwards.)
set -euo pipefail
HERE=$(cd "$(dirname "$0")" && pwd)
CACHE=$(realpath "$1") WORK=$(realpath -m "$2")
read -r _ file < "$HERE/busybox.sha256"
rm -rf "$WORK" && mkdir -p "$WORK"
python3 "$HERE/untar.py" "$CACHE/$file" "$WORK"
cd "$WORK/${file%.tar.bz2}"
make defconfig > /dev/null

# Switched off, by group. Each needs something Rustbelt doesn't have and
# isn't planned to have soon, so the applet could only ever fail:
off=(
  # Loadable kernel modules (Rustbelt has none).
  INSMOD RMMOD LSMOD MODPROBE DEPMOD MODINFO MODPROBE_SMALL
  # Traffic control: needs netlink, and 1.36.1's tc doesn't even compile
  # against current Linux headers (CBQ was removed from them).
  TC
  # Linux network configuration over netlink or raw packet sockets
  # (Rustbelt configures its network itself, see `ifconfig`).
  IP IPADDR IPLINK IPROUTE IPTUNNEL IPRULE IPNEIGH BRCTL IFPLUGD NAMEIF
  TUNCTL VCONFIG IFENSLAVE ETHER_WAKE ARPING ZCIP UDHCPC UDHCPD DHCPRELAY
  UDHCPC6 DUMPLEASES NBDCLIENT
  # Flash chips, I2C buses, PCI/USB listings, real-time clock, watchdog:
  # hardware Rustbelt doesn't expose (no /dev/mtd*, /dev/i2c-*, /sys).
  NANDWRITE NANDDUMP UBIATTACH UBIDETACH UBIMKVOL UBIRMVOL UBIRSVOL
  UBIUPDATEVOL UBIRENAME I2CGET I2CSET I2CDUMP I2CDETECT I2CTRANSFER LSPCI LSUSB HWCLOCK
  WATCHDOG DEVMEM ACPID BEEP SETSERIAL
  # Linux console fonts, keymaps and framebuffer ioctls (Rustbelt's console
  # and framebuffer work differently).
  LOADFONT SETFONT KBD_MODE LOADKMAP DUMPKMAP SETKEYCODES FBSET FBSPLASH CONSPY
  # Hot-plug (uevents), swap, loop devices, RAID, floppies, ramdisks,
  # namespaces and switching the root: kernel features Rustbelt lacks.
  MDEV UEVENT MKSWAP SWAPON SWAPOFF LOSETUP RAIDAUTORUN FDFORMAT FDFLUSH
  FREERAMDISK EJECT BLKDISCARD FSFREEZE RDEV PIVOT_ROOT SWITCH_ROOT NSENTER
  UNSHARE SETARCH LINUX32 LINUX64 ADJTIMEX
)
# Switched on (defconfig has them off):
on=(
  # busybox lives off PATH (/usr/lib/busybox), so when one applet runs
  # another (tar -z runs gzip, xargs and find -exec run their command,
  # adduser runs addgroup) it must not look for it on PATH: with this it
  # runs its own applet through /proc/self/exe instead.
  FEATURE_PREFER_APPLETS
)
for o in "${on[@]}"; do
    grep -q "^# CONFIG_$o is not set" .config || { echo "[mkconfig] CONFIG_$o is not off in defconfig"; exit 1; }
    sed -i "s/^# CONFIG_$o is not set/CONFIG_$o=y/" .config
done
for o in "${off[@]}"; do
    grep -q "^CONFIG_$o=y" .config || { echo "[mkconfig] CONFIG_$o is not in defconfig"; exit 1; }
    sed -i "s/^CONFIG_$o=y/# CONFIG_$o is not set/" .config
done
{ yes "" || true; } | make oldconfig > /dev/null   # (yes ends by SIGPIPE)
# Drop the generated date line so the file only changes when options do.
grep -v '^# [A-Z][a-z][a-z] [A-Z][a-z][a-z] ' .config > "$HERE/busybox.config"
echo "[mkconfig] wrote $HERE/busybox.config: $(grep -c '=y' "$HERE/busybox.config") options on, ${#off[@]} applets switched off, ${#on[@]} option(s) switched on"