/*
* Copyright 2015-present Facebook, Inc.
*
* Licensed 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 com.facebook.buck.util.network.hostname;
import com.sun.jna.LastErrorException;
import com.sun.jna.Native;
import com.sun.jna.Platform;
import com.sun.jna.ptr.IntByReference;
import java.io.IOException;
public class HostnameFetching {
private static final int HOSTNAME_MAX_LEN = 512;
// Utility class; do not instantiate.
private HostnameFetching() {}
public static String getHostname() throws IOException {
if (Platform.isWindows()) {
return getHostnameWin32();
} else {
return getHostnamePosix();
}
}
private static String getHostnamePosix() throws IOException {
byte[] hostnameBuf = new byte[HOSTNAME_MAX_LEN];
try {
// Subtract 1 to ensure NUL termination.
HostnameFetchingPosixLibrary.gethostname(hostnameBuf, hostnameBuf.length - 1);
return Native.toString(hostnameBuf);
} catch (LastErrorException e) {
throw new IOException(e);
}
}
private static String getHostnameWin32() throws IOException {
char[] hostnameBuf = new char[HOSTNAME_MAX_LEN];
IntByReference hostnameBufLen = new IntByReference(hostnameBuf.length);
boolean result =
HostnameFetchingWin32Library.INSTANCE.GetComputerNameEx(
HostnameFetchingWin32Library.NAME_TYPE_DNS_HOSTNAME, hostnameBuf, hostnameBufLen);
if (!result) {
throw new IOException(
String.format("Call to GetComputerNameEx failed with code %d", Native.getLastError()));
}
return new String(hostnameBuf, 0, hostnameBufLen.getValue());
}
}