commit 5a07adc5853c08fcc4a24c00f5e7d6c65fbe318d
Author: Michael Raitza <spacefrogg-git@meterriblecrew.net>
Date:   Wed Dec 2 18:51:52 2020 +0100

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..aa1395f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+result
+/.redo
+**/.do_built*
+**/*.did
diff --git a/README.org b/README.org
new file mode 100644
index 0000000..b6a40a0
--- /dev/null
+++ b/README.org
@@ -0,0 +1,18 @@
+#+TITLE: Nix flake
+#+AUTHOR: spacefrogg
+#+EMAIL: git@spacefrogg.net
+#+options: toc:nil
+
+* Development
+  This comes with a self-contained redo toolchain to help in working with the
+  flake. It basically deploys any input flake into the =tmp= directory for easier
+  access.
+
+  redo targets under =tmp/= come in three kinds:
+  - =clean= :: will remove all build products under =tmp/=
+  - =<flake>= :: will make sure a store path to =<flake>= exists and puts an
+    indirect root into =tmp/<flake>=.
+  - =<flake>.rw= :: will make sure a store path to =<flake>= exists and will
+    copy its contents to =tmp/.<flake>.rw= and will link to it from
+    =tmp/<flake>.rw=. (Rationale: On Linux, directories cannot denote reliable
+    targets due to their non-trivial relation to modification time.)
diff --git a/do b/do
new file mode 100755
index 0000000..909b5c6
--- /dev/null
+++ b/do
@@ -0,0 +1,446 @@
+#!/usr/bin/env sh
+#
+# A minimal alternative to djb redo that doesn't support incremental builds.
+# For the full version, visit http://github.com/apenwarr/redo
+#
+# The author disclaims copyright to this source file and hereby places it in
+# the public domain. (2010 12 14; updated 2019 02 24)
+#
+USAGE="
+usage: do [-d] [-x] [-v] [-c] <targets...>
+  -d  print extra debug messages (mostly about dependency checks)
+  -v  run .do files with 'set -v'
+  -x  run .do files with 'set -x'
+  -c  clean up all old targets before starting
+
+  Note: do is an implementation of redo that does *not* check dependencies.
+  It will never rebuild a target it has already built, unless you use -c.
+"
+
+# CDPATH apparently causes unexpected 'cd' output on some platforms.
+unset CDPATH
+
+# By default, no output coloring.
+green=""
+bold=""
+plain=""
+
+if [ -n "$TERM" -a "$TERM" != "dumb" ] && tty <&2 >/dev/null 2>&1; then
+	green="$(printf '\033[32m')"
+	bold="$(printf '\033[1m')"
+	plain="$(printf '\033[m')"
+fi
+
+# The 'seq' command is not available on all platforms.
+_seq() {
+	local x=0 max="$1"
+	while [ "$x" -lt "$max" ]; do
+		x=$((x + 1))
+		echo "$x"
+	done
+}
+
+# Split $1 into a dir part ($_dirsplit_dir) and base filename ($_dirsplit_base)
+_dirsplit() {
+	_dirsplit_base=${1##*/}
+	_dirsplit_dir=${1%$_dirsplit_base}
+}
+
+# Like /usr/bin/dirname, but avoids a fork and uses _dirsplit semantics.
+qdirname() (
+	_dirsplit "$1"
+	dir=${_dirsplit_dir%/}
+	echo "${dir:-.}"
+)
+
+_dirsplit "$0"
+REDO=$(cd "$(env pwd -P)" &&
+	cd "${_dirsplit_dir:-.}" &&
+	echo "$PWD/$_dirsplit_base")
+export REDO
+_cmd=$_dirsplit_base
+
+DO_TOP=
+if [ -z "$DO_BUILT" ]; then
+	export _do_opt_debug=
+	export _do_opt_exec=
+	export _do_opt_verbose=
+	export _do_opt_clean=
+fi
+while getopts 'dxvcj:h?' _opt; do
+	case $_opt in
+		d) _do_opt_debug=1 ;;
+		x) _do_opt_exec=x ;;
+		v) _do_opt_verbose=v ;;
+		c) _do_opt_clean=1 ;;
+		j) ;;  # silently ignore, for compat with real redo
+		\?|h|*) printf "%s" "$USAGE" >&2
+		   exit 99
+		   ;;
+	esac
+done
+shift "$((OPTIND - 1))"
+_debug() {
+	[ -z "$_do_opt_debug" ] || echo "$@" >&2
+}
+
+if [ -z "$DO_BUILT" -a "$_cmd" != "redo-whichdo" ]; then
+	DO_TOP=1
+	if [ "$#" -eq 0 ] && [ "$_cmd" = "do" -o "$_cmd" = "redo" ]; then
+		set all  # only toplevel redo has a default target
+	fi
+	export DO_STARTDIR="$(env pwd -P)"
+	# If starting /bin/pwd != $PWD, this will fix it.
+	# That can happen when $PWD contains symlinks that the shell is
+	# trying helpfully (but unsuccessfully) to hide from the user.
+	cd "$DO_STARTDIR" || exit 99
+	export DO_BUILT="$PWD/.do_built"
+	if [ -z "$_do_opt_clean" -a -e "$DO_BUILT" ]; then
+		echo "do: Incremental mode. Use -c for clean rebuild." >&2
+	fi
+	: >>"$DO_BUILT"
+	sort -u "$DO_BUILT" >"$DO_BUILT.new"
+	while read f; do
+		[ -n "$_do_opt_clean" ] && printf "%s\0%s.did\0" "$f" "$f"
+		printf "%s.did.tmp\0" "$f"
+	done <"$DO_BUILT.new" |
+	xargs -0 rm -f 2>/dev/null
+	mv "$DO_BUILT.new" "$DO_BUILT"
+	export DO_PATH="$DO_BUILT.dir"
+	export PATH="$DO_PATH:$PATH"
+	rm -rf "$DO_PATH"
+	mkdir "$DO_PATH"
+	for d in redo redo-ifchange redo-whichdo; do
+		ln -s "$REDO" "$DO_PATH/$d"
+	done
+	for d in redo-ifcreate redo-stamp redo-always redo-ood \
+	    redo-targets redo-sources; do
+	        echo "#!/bin/sh" >"$DO_PATH/$d"
+		chmod a+rx "$DO_PATH/$d"
+	done
+fi
+
+
+# Chop the "file" part off a /path/to/file pathname.
+# Note that if the filename already ends in a /, we just remove the slash.
+_updir()
+{
+	local v="${1%/*}"
+	[ "$v" != "$1" ] && echo "$v"
+	# else "empty" which means we went past the root
+}
+
+
+# Returns true if $1 starts with $2.
+_startswith()
+{
+	[ "${1#"$2"}" != "$1" ]
+}
+
+
+# Returns true if $1 ends with $2.
+_endswith()
+{
+	[ "${1%"$2"}" != "$1" ]
+}
+
+
+# Prints $1 if it's absolute, or $2/$1 if $1 is not absolute.
+_abspath()
+{
+	local here="$2" there="$1"
+	if _startswith "$1" "/"; then
+		echo "$1"
+	else
+		echo "$2/$1"
+	fi
+}
+
+
+# Prints $1 as a path relative to $PWD (not starting with /).
+# If it already doesn't start with a /, doesn't change the string.
+_relpath()
+{
+	local here="$2" there="$1" out= hadslash=
+	#echo "RP start '$there' hs='$hadslash'" >&2
+	_startswith "$there" "/" || { echo "$there" && return; }
+	[ "$there" != "/" ] && _endswith "$there" "/" && hadslash=/
+	here=${here%/}/
+	while [ -n "$here" ]; do
+		#echo "RP out='$out' here='$here' there='$there'" >&2
+		[ "${here%/}" = "${there%/}" ] && there= && break;
+		[ "${there#$here}" != "$there" ] && break
+		out=../$out
+		_dirsplit "${here%/}"
+		here=$_dirsplit_dir
+	done
+	there=${there#$here}
+	if [ -n "$there" ]; then
+		echo "$out${there%/}$hadslash"
+	else
+		echo "${out%/}$hadslash"
+	fi
+}
+
+
+# Prints a "normalized relative" path, with ".." resolved where possible.
+# For example, a/b/../c will be reduced to just a/c.
+_normpath()
+(
+	local path="$1" relto="$2" out= isabs=
+	#echo "NP start '$path'" >&2
+	if _startswith "$path" "/"; then
+		isabs=1
+	else
+		path="${relto%/}/$path"
+	fi
+	set -f
+	IFS=/
+	for d in ${path%/}; do
+		#echo "NP out='$out' d='$d'" >&2
+		if [ "$d" = ".." ]; then
+			out=$(_updir "${out%/}")/
+		else
+			out=$out$d/
+		fi
+	done
+	#echo "NP out='$out' (done)" >&2
+	out=${out%/}
+	if [ -n "$isabs" ]; then
+		echo "${out:-/}"
+	else
+		_relpath "${out:-/}" "$relto"
+	fi
+)
+
+
+# Prints a "real" path, with all symlinks resolved where possible.
+_realpath()
+{
+	local path="$1" relto="$2" isabs= rest=
+	if _startswith "$path" "/"; then
+		isabs=1
+	else
+		path="${relto%/}/$path"
+	fi
+	(
+		for d in $(_seq 100); do
+			#echo "Trying: $PWD--$path" >&2
+			if cd -P "$path" 2>/dev/null; then
+				# success
+				pwd=$(env pwd -P)
+				#echo "  chdir ok: $pwd--$rest" >&2
+				np=$(_normpath "${pwd%/}/$rest" "$relto")
+				if [ -n "$isabs" ]; then
+					echo "$np"
+				else
+					_relpath "$np" "$relto"
+				fi
+				break
+			fi
+			_dirsplit "${path%/}"
+			path=$_dirsplit_dir
+			rest="$_dirsplit_base/$rest"
+		done
+	)
+}
+
+
+# List the possible names for default*.do files in dir $1 matching the target
+# pattern in $2.  We stop searching when we find the first one that exists.
+_find_dofiles_pwd()
+{
+	local dodir="$1" dofile="$2"
+	_startswith "$dofile" "default." || dofile=${dofile#*.}
+	while :; do
+		dofile=default.${dofile#default.*.}
+		echo "$dodir$dofile"
+		[ -e "$dodir$dofile" ] && return 0
+		[ "$dofile" = default.do ] && break
+	done
+	return 1
+}
+
+
+# List the possible names for default*.do files in $PWD matching the target
+# pattern in $1.  We stop searching when we find the first name that works.
+# If there are no matches in $PWD, we'll search in .., and so on, to the root.
+_find_dofiles()
+{
+	local target="$1" dodir= dofile= newdir=
+	_debug "find_dofile: '$PWD' '$target'"
+	dofile="$target.do"
+	echo "$dofile"
+	[ -e "$dofile" ] && return 0
+
+	# Try default.*.do files, walking up the tree
+	_dirsplit "$dofile"
+	dodir=$_dirsplit_dir
+	dofile=$_dirsplit_base
+	[ -n "$dodir" ] && dodir=${dodir%/}/
+	[ -e "$dodir$dofile" ] && return 0
+	for i in $(_seq 100); do
+		[ -n "$dodir" ] && dodir=${dodir%/}/
+		#echo "_find_dofiles: '$dodir' '$dofile'" >&2
+		_find_dofiles_pwd "$dodir" "$dofile" && return 0
+		newdir=$(_realpath "${dodir}.." "$PWD")
+		[ "$newdir" = "$dodir" ] && break
+		dodir=$newdir
+	done
+	return 1
+}
+
+
+# Print the last .do file returned by _find_dofiles.
+# If that file exists, returns 0, else 1.
+_find_dofile()
+{
+	local files="$(_find_dofiles "$1")"
+	rv=$?
+	#echo "files='$files'" >&2
+	[ "$rv" -ne 0 ] && return $rv
+	echo "$files" | {
+		while read -r linex; do line=$linex; done
+		printf "%s\n" "$line"
+	}
+}
+
+
+# Actually run the given $dofile with the arguments in $@.
+# Note: you should always run this in a subshell.
+_run_dofile()
+{
+	export DO_DEPTH="$DO_DEPTH  "
+	export REDO_TARGET="$PWD/$target"
+	local line1
+	set -e
+	read line1 <"$PWD/$dofile" || true
+	cmd=${line1#"#!/"}
+	if [ "$cmd" != "$line1" ]; then
+		set -$_do_opt_verbose$_do_opt_exec
+		exec /$cmd "$PWD/$dofile" "$@"
+	else
+		set -$_do_opt_verbose$_do_opt_exec
+		# If $dofile is empty, "." might not change $? at
+		# all, so we clear it first with ":".
+		:; . "$PWD/$dofile"
+	fi
+}
+
+
+# Find and run the right .do file, starting in dir $1, for target $2,
+# providing a temporary output file as $3.  Renames the temp file to $2 when
+# done.
+_do()
+{
+	local dir="$1" target="$1$2" tmp="$1$2.redo.tmp" tdir=
+	local dopath= dodir= dofile= ext=
+	if [ "$_cmd" = "redo" ] ||
+	    ( [ ! -e "$target" -o -d "$target" ] &&
+	      [ ! -e "$target.did" ] ); then
+		printf '%sdo  %s%s%s%s\n' \
+			"$green" "$DO_DEPTH" "$bold" "$target" "$plain" >&2
+		dopath=$(_find_dofile "$target")
+		if [ ! -e "$dopath" ]; then
+			echo "do: $target: no .do file ($PWD)" >&2
+			return 1
+		fi
+		_dirsplit "$dopath"
+		dodir=$_dirsplit_dir dofile=$_dirsplit_base
+		if _startswith "$dofile" "default."; then
+			ext=${dofile#default}
+			ext=${ext%.do}
+		else
+			ext=
+		fi
+		target=$PWD/$target
+		tmp=$PWD/$tmp
+		cd "$dodir" || return 99
+		target=$(_relpath "$target" "$PWD") || return 98
+		tmp=$(_relpath "$tmp" "$PWD") || return 97
+		base=${target%$ext}
+		tdir=$(qdirname "$target")
+		[ ! -e "$DO_BUILT" ] || [ ! -w "$tdir/." ] ||
+		: >>"$target.did.tmp"
+		# $qtmp is a temporary file used to capture stdout.
+		# Since it might be accidentally deleted as a .do file
+		# does its work, we create it, then open two fds to it,
+		# then immediately delete the name.  We use one fd to
+		# redirect to stdout, and the other to read from after,
+		# because there's no way to fseek(fd, 0) in sh.
+		qtmp=$DO_PATH/do.$$.tmp
+		(
+			rm -f "$qtmp"
+			( _run_dofile "$target" "$base" "$tmp" >&3 3>&- 4<&- )
+			rv=$?
+			if [ $rv != 0 ]; then
+				printf "do: %s%s\n" "$DO_DEPTH" \
+					"$target: got exit code $rv" >&2
+				rm -f "$tmp.tmp" "$tmp.tmp2" "$target.did"
+				return $rv
+			fi
+			echo "$PWD/$target" >>"$DO_BUILT"
+			if [ ! -e "$tmp" ]; then
+				# if $3 wasn't created, copy from stdout file
+				cat <&4 >$tmp
+				# if that's zero length too, forget it
+				[ -s "$tmp" ] || rm -f "$tmp"
+			fi
+		) 3>$qtmp 4<$qtmp  # can't use "|| return" here...
+		# ...because "|| return" would mess up "set -e" inside the ()
+		# on some shells.  Running commands in "||" context, even
+		# deep inside, will stop "set -e" from functioning.
+		rv=$?
+		[ "$rv" = 0 ] || return "$rv"
+		mv "$tmp" "$target" 2>/dev/null
+		[ -e "$target.did.tmp" ] &&
+		mv "$target.did.tmp" "$target.did" ||
+		: >>"$target.did"
+	else
+		_debug "do  $DO_DEPTH$target exists." >&2
+	fi
+}
+
+
+# Implementation of the "redo" command.
+_redo()
+{
+	local i startdir="$PWD" dir base
+	set +e
+	for i in "$@"; do
+		i=$(_abspath "$i" "$startdir")
+		(
+			cd "$DO_STARTDIR" || return 99
+			i=$(_realpath "$(_relpath "$i" "$PWD")" "$PWD")
+			_dirsplit "$i"
+			dir=$_dirsplit_dir base=$_dirsplit_base
+			_do "$dir" "$base"
+		)
+		[ "$?" = 0 ] || return 1
+	done
+}
+
+
+# Implementation of the "redo-whichdo" command.
+_whichdo()
+{
+	_find_dofiles "$1"
+}
+
+
+case $_cmd in
+	do|redo|redo-ifchange) _redo "$@" ;;
+	redo-whichdo) _whichdo "$1" ;;
+	do.test) ;;
+	*) printf "do: '%s': unexpected redo command" "$_cmd" >&2; exit 99 ;;
+esac
+[ "$?" = 0 ] || exit 1
+
+if [ -n "$DO_TOP" ]; then
+	if [ -n "$_do_opt_clean" ]; then
+		echo "do: Removing stamp files..." >&2
+		[ ! -e "$DO_BUILT" ] ||
+		while read f; do printf "%s.did\0" "$f"; done <"$DO_BUILT" |
+		xargs -0 rm -f 2>/dev/null
+	fi
+fi
diff --git a/tmp/.gitignore b/tmp/.gitignore
new file mode 100644
index 0000000..beff5a9
--- /dev/null
+++ b/tmp/.gitignore
@@ -0,0 +1,3 @@
+*
+!*.do
+!.gitignore
diff --git a/tmp/default.do b/tmp/default.do
new file mode 100644
index 0000000..afb949a
--- /dev/null
+++ b/tmp/default.do
@@ -0,0 +1,40 @@
+#!/bin/sh
+# This do script creates an indirect root to an input flake
+
+exec >&2
+
+redo-ifchange ../flake.nix ../flake.lock || true
+
+resolve_flake() {
+    STORE_PATH=$(nix flake info --json --inputs-from .. "$2" | jq -r .path)
+
+    # Do this after 'info' to avoid unnecessary network activity. nix flake
+    # archive may try to download a flake although the store path is available.
+    if [ ! -d "$STORE_PATH" ]; then
+        nix flake archive --inputs-from .. "$2"
+    fi
+}
+
+case $2 in
+    # Resolves cleanup targets by their softlinks
+    clean)
+        redo-always || true
+        find . -type l -print -exec realpath -P --relative-base="$PWD" {} \+ |
+            while read p; do
+                if [ "$p" = "${p#/}" ]; then
+                    rm -rf -- "$p"
+                fi
+            done
+        ;;
+    *.rw)
+        resolve_flake "$@"
+        rm -rf -- ".$2"
+        cp --reflink=auto -r --no-preserve=mode "$STORE_PATH" ".$2"
+        ln -sf ".$2" "$3"
+        ;;
+    *)
+        resolve_flake "$@"
+        nix-store -r "$STORE_PATH" --indirect --add-root "$2"
+        [ "$2" = "$3" ] || mv "$2" "$3"
+        ;;
+esac