From 2705aa066b152c2583887dc558dd9822506d7362 Mon Sep 17 00:00:00 2001
From: root <root@vps-18a7a2b7.vps.ovh.ca>
Date: Thu, 22 Feb 2024 09:21:47 -0500
Subject: bash introspection experiments

---
 bash/SOURCES.bash             | 113 ++++++++++++++++++++++++++++++++++++++++++
 bash/bootstrap_SOURCES.bash   |   1 +
 bash/denominate-function.bash |  82 ++++++++++++++++++++++++++++++
 3 files changed, 196 insertions(+)
 create mode 100644 bash/SOURCES.bash
 create mode 120000 bash/bootstrap_SOURCES.bash
 create mode 100644 bash/denominate-function.bash

diff --git a/bash/SOURCES.bash b/bash/SOURCES.bash
new file mode 100644
index 0000000..a274223
--- /dev/null
+++ b/bash/SOURCES.bash
@@ -0,0 +1,113 @@
+#!/bin/bash
+source()
+{
+	if	[[ $1 != */* ]] &&
+	    	(
+			command -v base64_embedded_source__"$1" ||
+			command -v src/"$1"
+		) >&2 # >/dev/null
+	then
+		rewrite_self \
+			"$1" \
+			src/"$1" \
+			base64_embedded_source__"$1" \
+			"${@:2}"
+	else
+		builtin source "$@"
+	fi
+}
+
+rewrite_self()
+{
+	# TODO: Check if version in src/ updates this version
+	# by checking for its hash in a record kept in the source
+	# file in src/
+	if command -v "$3" >/dev/null
+	then
+		(
+			set +e
+			sha256sum <("$3") >&2
+			sha256sum <(builtin source "$2" "${@:4}" && "$3") >&2
+		)
+		builtin source \
+			<("$3") \
+			"${@:4}"
+	       	return
+	fi
+	[ -f "$2" -a -r "$2" ] || return
+	declare -n tmpfile=tmpfile${RANDOM}
+	tmpfile=$(mktemp) || return
+	if 	embed "$1" "$2" > "$tmpfile" &&
+		builtin source "$tmpfile" &&
+		command -v "$3" >/dev/null &&
+		builtin source <("$3") "${@:4}" &&
+		[ -w "$0" ] &&
+		sed \
+			-i~"$(date -Ins)" \
+			-e "1 { r ${tmpfile}"$'\n'" }" \
+			"$0"
+	then
+		local r=0
+	else
+		local r=$?
+	fi
+	rm "$tmpfile"
+	return $r
+}
+
+embed()
+{
+	cat <<.
+base64_embedded_source__${1}()
+{
+	base64 -d <<.
+$(base64 < "$2" && echo .)
+}
+.
+}
+
+print_test_script_for_SOURCES.bash()
+{
+	cat <<.
+#!/bin/bash
+source SOURCES.bash
+source SOURCES.bash
+source rpc.bash
+: base64_embedded_source__rpc.bash
+: base64_embedded_source__dependencies.bash
+BASH_RPC_REMOTE_DEST=localhost \\
+	remote_run_function \\
+		source rpc.bash
+.
+}
+
+setup_test_dir()
+{
+	(
+		set -e
+		mkdir -p test_SOURCES.bash
+		cd test_SOURCES.bash
+		mkdir -p src
+		ln -sf -t src \
+			../../SOURCES.bash \
+			../../src/{rpc,dependencies}.bash
+		print_test_script_for_SOURCES.bash > test-SOURCES.bash
+	)
+}
+
+run_test()
+{
+	(
+		set -ex
+		cd test_SOURCES.bash
+		PATH=$PWD/src:$PATH bash test-SOURCES.bash || true
+		PATH=$PWD/src:$PATH bash test-SOURCES.bash
+	)
+}
+
+bootstrap_SOURCES.bash()
+{
+	setup_test_dir && run_test
+}
+
+[ "$0" = 'bootstrap_SOURCES.bash' ] && bootstrap_SOURCES.bash
diff --git a/bash/bootstrap_SOURCES.bash b/bash/bootstrap_SOURCES.bash
new file mode 120000
index 0000000..a0054dd
--- /dev/null
+++ b/bash/bootstrap_SOURCES.bash
@@ -0,0 +1 @@
+SOURCES.bash
\ No newline at end of file
diff --git a/bash/denominate-function.bash b/bash/denominate-function.bash
new file mode 100644
index 0000000..9e5cb31
--- /dev/null
+++ b/bash/denominate-function.bash
@@ -0,0 +1,82 @@
+#!/bin/bash
+denominate_function()
+{
+	declare -n func_name="$1"
+	local func_output_b64encoded output_hash
+	read -r -d '' \
+		func_output_b64encoded \
+		< <(base64) || [ "${func_output_b64encoded}" ]
+	read output_hash _ \
+		< <(base64 -d <<< "$func_output_b64encoded" | sha256sum)
+	[ ${#output_hash} = 64 ] || return
+	func_name=SHA256_${output_hash:0:32}
+	source <(cat <<END
+${func_name} ()
+{
+base64 -d <<.
+${func_output_b64encoded}
+.
+}
+END
+)
+}
+
+reverse_hash()
+{
+	case "$#.$1" in
+	2.SHA256 )
+		;;
+	1.SHA256_???????????????????????????????? )
+		set -- SHA256 "${1#SHA256_}"
+		;;
+	* )
+		return 1
+		;;
+	esac
+	case ${#2} in
+	32 | 64 )
+		set -- "${1}_${2: 0 : 32}"
+		;;
+	* )
+		return 1
+		;;
+	esac
+	(
+		set -o pipefail
+		set -e
+		declare -f "$1" |
+		sed -n -e '/^[	 ]*base64 -d <<[.]$/,/^[.]$/ { p }' |
+		sed -e '1 d ; $ d' |
+		base64 -d
+	)
+}
+
+example_input()
+{
+	sed -n -e '/^reverse_hash *()/ , /^}$/ p' <"$0"
+}
+
+set -e
+set -o pipefail
+
+if [ -t 0 ]
+then
+	if [ $# = 0 ]
+	then
+		denominate_function f < <(example_input)
+	else
+		denominate_function f <<< "$*"
+	fi
+else
+	denominate_function f
+fi
+
+read -r -d '' < <( reverse_hash "$f" | base64) || [ "$REPLY" ]
+if	read s _ < <( base64 -d <<< "$REPLY" | sha256sum ) &&
+	[ ${#s} -eq 64 -a "${s: 0 : 32}" = "${f: -32 : 32}" ]
+then
+	declare -f "$f" | grep . &&
+	printf '%s\n' "$f"
+else
+	false
+fi
-- 
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