Move creation of temporary directory to Java (#36002)

In the long run we want to move all of startup to a Java program. This
will simplify our startup scripts and make maintenance of startup less
dependent on the underlying platform that we run on. This commit moves
the creation of the temporary directory off of system-dependent commands
and onto a simple Java program.

distribution/src/bin/elasticsearch-env

@@ -81,13 +81,5 @@ ES_DISTRIBUTION_FLAVOR=${es.distribution.flavor}
 ES_DISTRIBUTION_TYPE=${es.distribution.type}
 
 if [ -z "$ES_TMPDIR" ]; then
-  set +e
-  mktemp --version 2>&1 | grep coreutils > /dev/null
-  mktemp_coreutils=$?
-  set -e
-  if [ $mktemp_coreutils -eq 0 ]; then
-    ES_TMPDIR=`mktemp -d --tmpdir "elasticsearch.XXXXXXXX"`
-  else
-    ES_TMPDIR=`mktemp -d -t elasticsearch`
-  fi
+  ES_TMPDIR=`"$JAVA" -cp "$ES_CLASSPATH" org.elasticsearch.tools.launchers.TempDirectory`
 fi

distribution/src/bin/elasticsearch-env.bat

@@ -57,8 +57,5 @@ set ES_DISTRIBUTION_FLAVOR=${es.distribution.flavor}
 set ES_DISTRIBUTION_TYPE=${es.distribution.type}
 
 if not defined ES_TMPDIR (
-  set ES_TMPDIR=!TMP!\elasticsearch
-  if not exist "!ES_TMPDIR!" (
-    mkdir "!ES_TMPDIR!"
-  )
+  for /f "tokens=* usebackq" %%a in (`"%JAVA% -cp "!ES_CLASSPATH!" "org.elasticsearch.tools.launchers.TempDirectory""`) do set ES_TMPDIR=%%a
 )

distribution/tools/launchers/src/main/java/org/elasticsearch/tools/launchers/Launchers.java

@@ -21,6 +21,11 @@
 
 import org.elasticsearch.tools.java_version_checker.SuppressForbidden;
 
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileAttribute;
+
 /**
  * Utility methods for launchers.
  */
@@ -56,4 +61,9 @@ static void exit(final int status) {
         System.exit(status);
     }
 
+    @SuppressForbidden(reason = "Files#createTempDirectory(String, FileAttribute...)")
+    static Path createTempDirectory(final String prefix, final FileAttribute<?>... attrs) throws IOException {
+        return Files.createTempDirectory(prefix, attrs);
+    }
+
 }

distribution/tools/launchers/src/main/java/org/elasticsearch/tools/launchers/TempDirectory.java

@@ -0,0 +1,59 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.tools.launchers;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+
+/**
+ * Provides a path for a temporary directory. On non-Windows OS, this will be created as a sub-directory of the default temporary directory.
+ * Note that this causes the created temporary directory to be a private temporary directory.
+ */
+final class TempDirectory {
+
+    /**
+     * The main entry point. The exit code is 0 if we successfully created a temporary directory as a sub-directory of the default
+     * temporary directory and printed the resulting path to the console.
+     *
+     * @param args the args to the program which should be empty
+     * @throws IOException if an I/O exception occurred while creating the temporary directory
+     */
+    public static void main(final String[] args) throws IOException {
+        if (args.length != 0) {
+            throw new IllegalArgumentException("expected zero arguments but was " + Arrays.toString(args));
+        }
+        /*
+         * On Windows, we avoid creating a unique temporary directory per invocation lest we pollute the temporary directory. On other
+         * operating systems, temporary directories will be cleaned automatically via various mechanisms (e.g., systemd, or restarts).
+         */
+        final Path path;
+        if (System.getProperty("os.name").startsWith("Windows")) {
+            path = Paths.get(System.getProperty("java.io.tmpdir"), "elasticsearch");
+            Files.createDirectories(path);
+        } else {
+            path = Launchers.createTempDirectory("elasticsearch-");
+        }
+        Launchers.outPrintln(path.toString());
+    }
+
+}