chg: remove requirement on ``sha256sum``

Also provide and use a ``hash_get`` function that will choose in the
available binary program. It supports ``sha512sum``, ``md5sum`` (GNU
version) and ``md5`` (BSD version).

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

bin/compose

@@ -17,16 +17,18 @@
 
 ANSI_ESC=$'\e['
 
-
-md5_compat() {
-    if get_path md5sum >/dev/null; then
-        md5_compat() { md5sum | cut -c -32; }
+hash_get() {
+    if get_path sha256sum >/dev/null; then
+        hash_get() { local x; x=$(sha256sum) || return 1; echo "${x:0:32}"; }
+    elif get_path md5sum >/dev/null; then
+        hash_get() { local x; x=$(md5sum) || return 1; echo "${x:0:32}"; }
     elif get_path md5 >/dev/null; then
-        md5_compat() { md5; }
+        hash_get() { md5; }
     else
-        die "$exname: required GNU or BSD date not found"
+        err "required GNU md5sum or BSD md5 not found"
+        return 1
     fi
-    md5_compat
+    hash_get
 }
 
 
@@ -408,14 +410,14 @@ get_hash_image() {
         p0 ""
         [ -n "$override" ] && cat "$override"
         true
-    } | md5_compat
+    } | hash_get
     return "${PIPESTATUS[0]}"
 }
 
 
 get_compose_file_opt() {
     local hash_bin="$1" override="$2" \
-          cache_file="$COMPOSE_LAUNCHER_CACHE/$FUNCNAME.cache.$(p0 "$@" | md5_compat)"
+          cache_file="$COMPOSE_LAUNCHER_CACHE/$FUNCNAME.cache.$(p0 "$@" | hash_get)"
     if [ -e "$cache_file" ]; then
         cat "$cache_file" &&
         touch "$cache_file" || return 1
@@ -454,7 +456,7 @@ get_compose_file_opt() {
 
 replace_compose_file_opt() {
     local hash_bin="$1" override="$2" \
-          cache_file="$COMPOSE_LAUNCHER_CACHE/$FUNCNAME.cache.$(p0 "$@" | md5_compat)"
+          cache_file="$COMPOSE_LAUNCHER_CACHE/$FUNCNAME.cache.$(p0 "$@" | hash_get)"
     if [ -e "$cache_file" ]; then
         cat "$cache_file" &&
         touch "$cache_file" || return 1
@@ -565,7 +567,7 @@ get_compose_single_opts_list() {
 
 
 get_volume_opt() {
-    local cache_file="$COMPOSE_LAUNCHER_CACHE/$FUNCNAME.cache.$(p0 "$@" | md5_compat)"
+    local cache_file="$COMPOSE_LAUNCHER_CACHE/$FUNCNAME.cache.$(p0 "$@" | hash_get)"
     if [ -e "$cache_file" ]; then
         cat "$cache_file" &&
         touch "$cache_file" || return 1
@@ -800,7 +802,7 @@ mk_docker_run_options() {
     ## get TZ value and prepare TZ_PATH
     TZ=$(get_tz) || return 1
     mkdir -p "${TZ_PATH}"
-    TZ_PATH="${TZ_PATH}/$(e "$TZ" | sha256sum | cut -c 1-8)" || return 1
+    TZ_PATH="${TZ_PATH}/$(e "$TZ" | hash_get | cut -c 1-8)" || return 1
     [ -e "$TZ_PATH" ] || e "$TZ" > "$TZ_PATH"
 
     ## CACHE/DATA DIRS
@@ -913,7 +915,7 @@ mk_docker_run_options() {
             ## Docker host is not same linux than WSL, so
             ## access to root files are not the same.
             ##YYYvlab, check on cp where is the base
-            dst="$COMPOSE_LAUNCHER_CACHE/compose.$(md5_compat < "$compose_file").yml"
+            dst="$COMPOSE_LAUNCHER_CACHE/compose.$(hash_get < "$compose_file").yml"
             cp "$compose_file" "$dst"
             ## docker host start with /c/... whereas WSL could start with /mnt/c/...
             local="$dst"
@@ -938,12 +940,11 @@ mk_docker_run_options() {
     clean_unused_sessions
     filename=$(mktemp -p /tmp/ -t launch_opts-XXXXXXXXXXXXXXXX)
     p0 "${docker_run_opts[@]}" > "$filename"
-    sha=$(sha256sum "$filename")
-    sha=${sha:0:64}
-    src="$SESSION_DIR/$UID-$sha"
-    dest="/var/lib/compose/sessions/$UID-$sha"
+    hash=$(hash_get < "$filename") || return 1
+    src="$SESSION_DIR/$UID-$hash"
+    dest="/var/lib/compose/sessions/$UID-$hash"
     additional_docker_run_opts=(
-        "-v" "$SESSION_DIR/$UID-$sha:$dest:ro"
+        "-v" "$SESSION_DIR/$UID-$hash:$dest:ro"
         "-e" "COMPOSE_LAUNCHER_OPTS=$dest"
         "-e" "COMPOSE_LAUNCHER_BIN=$COMPOSE_LAUNCHER_BIN"
     )