bash introspection experiments

3 files changed, 196 insertions, 0 deletions

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