build-using-nix.sh

#!/usr/bin/env bash

# this is entirely optional and for development purposes only
# just use `nix-build` and you should be fine

# build with ccache and without /bin/sh present
# your nix needs experimental-options = ca-derivations
# and you need root access / to be a trusted user

set -ue

CCACHE_HOST=/var/cache/ccache
mkdir -p $CCACHE_HOST/data
sudo chgrp nixbld $CCACHE_HOST $CCACHE_HOST/data
sudo chmod g+ws $CCACHE_HOST $CCACHE_HOST/data

if [[ ! -e $CCACHE_HOST/bin/ccache ]]; then
	nix build 'nixpkgs#pkgsStatic.ccache' --out-link $CCACHE_HOST/result
	mkdir -p $CCACHE_HOST/bin
	cp --reflink=auto $CCACHE_HOST/result/bin/ccache $CCACHE_HOST/bin/ccache
	rm $CCACHE_HOST/result
fi

[[ -e $CCACHE_HOST/setup ]] || cat > $CCACHE_HOST/setup <<\EOF
mkdir -p .ccache-wrappers
for prefix in '' x86_64-linux- x86_64-linux-musl- x86_64-linux-unknown-; do
	for name in cc c++ gcc g++ clang clang++ tcc; do
		if command -v $prefix$name; then
			ln -s /ccache/bin/ccache .ccache-wrappers/$prefix$name
		fi
	done
done
export PATH="$(pwd)/.ccache-wrappers:/ccache/bin:$PATH"
export CCACHE_DIR="/ccache/data/$1"
export CCACHE_COMPILERCHECK=content
export CCACHE_SLOPPINESS=include_file_ctime,include_file_mtime
export CCACHE_MAXSIZE=0
export CCACHE_UMASK=005
export CCACHE_NOHASHDIR=1
export CCACHE_BASEDIR="$(pwd)"
EOF
chmod +x $CCACHE_HOST/setup

nix-build -A stage1.protomusl
nix-build -A stage1.protobusybox
nix-build -A stage1.tinycc
sudo env "NIX_CONFIG=sandbox-paths = /ccache=$CCACHE_HOST" nix-build "$@"