org.archive.util.FilesystemLinkMaker Maven / Gradle / Ivy
/*
* This file is part of the Heritrix web crawler (crawler.archive.org).
*
* Licensed to the Internet Archive (IA) by one or more individual
* contributors.
*
* The IA 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.archive.util;
import java.io.File;
import java.io.IOException;
import java.util.logging.Logger;
import com.sun.jna.Native;
import com.sun.jna.Platform;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;
import com.sun.jna.win32.StdCallLibrary;
/**
* Wrapper for platform-dependent hard link creation.
*
* @see http://stackoverflow.com/questions/783075/creating-a-hard-link-in-java/3023349#3023349
*/
public class FilesystemLinkMaker {
private static final Logger logger = Logger.getLogger(FilesystemLinkMaker.class.getName());
// see https://github.com/twall/jna/blob/master/www/GettingStarted.md
public interface Kernel32Library extends StdCallLibrary {
Kernel32Library INSTANCE = (Kernel32Library) (Platform.isWindows()
? Native.loadLibrary("kernel32", Kernel32Library.class)
: null);
/* http://msdn.microsoft.com/en-us/library/aa379560%28VS.85%29.aspx
* http://en.wikipedia.org/wiki/Java_Native_Access
*
* typedef struct _SECURITY_ATTRIBUTES {
* DWORD nLength;
* LPVOID lpSecurityDescriptor;
* BOOL bInheritHandle;
* } SECURITY_ATTRIBUTES, *PSECURITY_ATTRIBUTES, *LPSECURITY_ATTRIBUTES;
*/
public static class LPSECURITY_ATTRIBUTES extends Structure {
public int nLength;
public Pointer lpSecurityDescriptor;
public boolean bInheritHandle;
}
/*
* http://msdn.microsoft.com/en-us/library/aa363860%28VS.85%29.aspx
* CreateHardLink is a macro that maps to CreateHardLinkA (ansi) or
* CreateHardLinkW (unicode). In initial testing CreateHardLinkW()
* worked, but then it stopped working... go figure.
*/
boolean CreateHardLinkA(String newPath, String existingPath, LPSECURITY_ATTRIBUTES lpSecurityAttributes);
// boolean CreateHardLinkW(String newPath, String existingPath, LPSECURITY_ATTRIBUTES lpSecurityAttributes);
// http://msdn.microsoft.com/en-us/library/aa363866%28v=VS.85%29.aspx
boolean CreateSymbolicLinkA(String newPath, String existingPath, LPSECURITY_ATTRIBUTES lpSecurityAttributes);
}
/**
* Wrapper over platform-dependent system calls to create a hard link.
*
* @return true on success
*/
// XXX could handle errors better (examine errno, throw exception...)
public static boolean makeHardLink(String existingPath, String newPath) {
try {
if (Platform.isWindows()) {
return Kernel32Library.INSTANCE.CreateHardLinkA(newPath, existingPath, null);
} else {
int status = CLibrary.INSTANCE.link(existingPath, newPath);
return status == 0;
}
} catch (UnsatisfiedLinkError e) {
// see https://webarchive.jira.com/browse/HER-1979
logger.warning("hard links not supported on this platform - " + e);
return false;
}
}
/**
* Wrapper over platform-dependent system calls to create a symbolic link.
*
* @return true on success
*/
// XXX could handle errors better (examine errno, throw exception...)
public static boolean makeSymbolicLink(String existingPath, String newPath) {
try {
if (Platform.isWindows()) {
return Kernel32Library.INSTANCE.CreateSymbolicLinkA(newPath, existingPath, null);
} else {
int status = CLibrary.INSTANCE.symlink(existingPath, newPath);
return status == 0;
}
} catch (UnsatisfiedLinkError e) {
// see https://webarchive.jira.com/browse/HER-1979
logger.warning("symbolic links not supported on this platform - " + e);
return false;
}
}
public static void main(String[] args) throws IOException {
File existingPath = File.createTempFile("heritrixHardLinkTestExistingFile", ".tmp");
File newPath = File.createTempFile("heritrixHardLinkTestNewFile", ".tmp");
newPath.delete();
if (FilesystemLinkMaker.makeHardLink(existingPath.getAbsolutePath(), newPath.getAbsolutePath())) {
System.out.println("success - made hard link from " + newPath.getAbsolutePath() + " to " + existingPath.getAbsolutePath());
} else {
System.out.println("failed to make hard link from " + newPath.getAbsolutePath() + " to " + existingPath.getAbsolutePath());
}
existingPath = File.createTempFile("heritrixSymlinkTestExistingFile", ".tmp");
newPath = File.createTempFile("heritrixSymlinkTestNewFile", ".tmp");
newPath.delete();
if (FilesystemLinkMaker.makeSymbolicLink(existingPath.getPath(), newPath.getPath())) {
System.out.println("success - made symlink from " + newPath.getAbsolutePath() + " to " + existingPath.getAbsolutePath());
} else {
System.out.println("failed to make symlink from " + newPath.getAbsolutePath() + " to " + existingPath.getAbsolutePath());
}
}
}