tools: use mktemp to create the workspace directory

On some platforms, the TMPDIR environment variable is not set.

tools/update-npm.sh

@@ -11,16 +11,15 @@ if [ "$#" -le 0 ]; then
   exit 1
 fi
 
-WORKSPACE="$TMPDIR"update-npm-$NPM_VERSION/
+echo "Making temporary workspace"
 
-if [ -d "$WORKSPACE" ]; then
-  echo "Cleaning up old workspace"
-  rm -rf "$WORKSPACE"
-fi
+WORKSPACE=$(mktemp -d 2> /dev/null || mktemp -d -t 'tmp')
 
-echo "Making temporary workspace"
+cleanup () {
+  [ -d "$WORKSPACE" ] && rm -rf "$WORKSPACE"
+}
 
-mkdir -p "$WORKSPACE"
+trap cleanup INT TERM EXIT
 
 cd "$WORKSPACE"
 
@@ -40,11 +39,7 @@ rm -rf npm/
 
 echo "Copying new npm"
 
-tar zxf "$WORKSPACE"cli/release/npm-"$NPM_VERSION".tgz
-
-echo "Deleting temporary workspace"
-
-rm -rf "$WORKSPACE"
+tar zxf "$WORKSPACE"/cli/release/npm-"$NPM_VERSION".tgz
 
 echo ""
 echo "All done!"