chg: dev: [install.sh] refactor out the fetching of binary !minor

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

src/install.sh

@@ -215,6 +215,32 @@ get_charm_store() {
 }
 
 
+fetch_binary() {
+    local url="$1" name="$2" bin_path tmpfile
+    mkdir -p "$BIN_PATH" || return 1
+    info "Downloading '$name'..."
+    (
+        tmpfile=$(mktemp) && trap "rm -f '$tmpfile'" EXIT &&
+            curl -sS "$url" > "$tmpfile" &&
+            chmod +x "$tmpfile"
+        if [ -e "$BIN_PATH/$name" ] && diff "$tmpfile" "$BIN_PATH/$name"; then
+            echo "  .. Done (File '$BIN_PATH/$name' was already up to date.)"
+        else
+            mv "$tmpfile" "$BIN_PATH/$name"
+            echo "  .. Done !"
+        fi
+    ) || return 1
+    hash -r
+    if bin_path=$(type -p "$name"); then
+        if [ "$bin_path" != "$BIN_PATH/$name" ]; then
+            warn "Found a '$name' in \$PATH at '$bin_path'." \
+                 $'\n'"  That doesn't match expected location '$BIN_PATH/$name'." \
+                 $'\n'"  You might need to change you \$PATH to include '$BIN_PATH' before '${bin_path%/*}'."
+        fi
+    fi
+}
+
+
 install.linux() {
     depends docker curl git
 
@@ -230,29 +256,7 @@ install.linux() {
         COMPOSE_OPTION_FILE=/etc/compose/local.conf
     fi
 
-    ## COMPOSE
-    if compose=$(type -p "compose"); then
-        if [ "$compose" != "$BIN_PATH/compose" ]; then
-        warn "Found a 'compose' in \$PATH at '$compose' that doesn't match expected compose location '$BIN_PATH/compose'." \
-             "Not doing anything."
-        elif [ -L "$compose" ]; then
-            warn "Found a 'compose' at '$compose' that is a link. " \
-                 "Not doing anything."
-        else
-            compose=""  ## force overwrite
-        fi
-    fi
-    if [ -z "$compose" ]; then
-        mkdir -p "$BIN_PATH" || exit 1
-        info "Downloading 'compose'..."
-        (
-            set +x
-            curl -sS https://git.0k.io/0k-compose.git/plain/bin/compose > /tmp/compose
-            chmod -v +x /tmp/compose
-            mv -v /tmp/compose "$BIN_PATH/"
-        ) || exit 1
-        echo "  .. Done !"
-    fi
+    fetch_binary https://git.0k.io/0k-compose.git/plain/bin/compose compose
 
     if [[ ":$PATH:" != *":$BIN_PATH:"* ]]; then
         warn "Please ensure that '$BIN_PATH' is in your \$PATH to ensure" \