add: FileLinkUtilities

SVN: 6930

common/source/c/compile_linux_amd64.sh

+#! /bin/bash
+
+gcc -shared -fPIC unixlink.c -o ../../../libraries/filelink/amd64-Linux/jlink.so

common/source/c/compile_linux_i386.sh

+#! /bin/bash
+
+gcc -shared unixlink.c -I/usr/java/jdk1.5.0_13/include -I/usr/java/jdk1.5.0_13/include/linux -o ../../../libraries/filelink/i386-Linux/jlink.so

common/source/c/compile_macosx.sh

+#! /bin/bash
+
+gcc -bundle unixlink.c -I/System/Library/Frameworks/JavaVM.framework/Versions/Current/Headers -o "../../../libraries/filelink/i386-Mac OS X/jlink.so"
+

common/source/c/unixlink.c

+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <jni.h>
+
+JNIEXPORT jint JNICALL Java_ch_systemsx_cisd_common_utilities_FileLinkUtilities_hardlink
+  (JNIEnv *env, jclass clss, jstring filename, jstring linktarget)
+{
+    const char* pfilename;
+    const char* plinktarget;
+    jboolean isCopy;
+    int retval;
+
+    pfilename = (char *)(*env)->GetStringUTFChars(env, filename, &isCopy);
+    plinktarget = (char *)(*env)->GetStringUTFChars(env, linktarget, &isCopy);
+
+    retval = link(pfilename, plinktarget);
+    if (retval < 0)
+    {
+        retval = errno;
+    }
+
+    (*env)->ReleaseStringUTFChars(env, filename, pfilename);
+    (*env)->ReleaseStringUTFChars(env, linktarget, plinktarget);
+
+   return retval;
+}
+
+JNIEXPORT jint JNICALL Java_ch_systemsx_cisd_common_utilities_FileLinkUtilities_symlink
+  (JNIEnv *env, jclass clss, jstring filename, jstring linktarget)
+{
+    const char* pfilename;
+    const char* plinktarget;
+    jboolean isCopy;
+    int retval;
+
+    pfilename = (char *)(*env)->GetStringUTFChars(env, filename, &isCopy);
+    plinktarget = (char *)(*env)->GetStringUTFChars(env, linktarget, &isCopy);
+
+    retval = symlink(pfilename, plinktarget);
+    if (retval < 0)    { 
+        retval = errno; 
+    }
+
+    (*env)->ReleaseStringUTFChars(env, filename, pfilename);
+    (*env)->ReleaseStringUTFChars(env, linktarget, plinktarget);
+
+   return retval;
+}
+
+JNIEXPORT jstring JNICALL Java_ch_systemsx_cisd_common_utilities_FileLinkUtilities_strerror(JNIEnv *env, jclass clss, jint errnum)
+{
+    return (*env)->NewStringUTF(env, strerror(errnum));
+}

common/source/java/ch/systemsx/cisd/common/utilities/FileLinkUtilities.java

+/*
+ * Copyright 2008 ETH Zuerich, CISD
+ *
+ * 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 ch.systemsx.cisd.common.utilities;
+
+import java.io.File;
+
+/**
+ * A utility class that provides access to hard link and symbolic link creation on Unix platforms.
+ * 
+ * @author Bernd Rinn
+ */
+public class FileLinkUtilities
+{
+
+    private static boolean operational = false;
+
+    static
+    {
+        final String filename =
+                FileUtilities.tryCopyResourceToTempFile("/" + OSUtilities.getComputerPlatform()
+                        + "/jlink.so", "jlink", ".so");
+
+        if (filename != null)
+        {
+            final File linkLib = new File(filename);
+            if (linkLib.exists() && linkLib.canRead() && linkLib.isFile())
+            {
+                try
+                {
+                    System.load(filename);
+                    operational = true;
+                } catch (final Throwable err)
+                {
+                    System.err.printf("Native Link library '%s' failed to load:\n", filename);
+                    err.printStackTrace();
+                }
+            }
+        }
+    }
+
+    /** An exception that indicates that creating a link failed. */
+    public static final class FileLinkException extends RuntimeException
+    {
+        private static final long serialVersionUID = 1L;
+
+        private FileLinkException(String type, String source, String target, String errorMessage)
+        {
+            super(String.format("Creating %s link '%s' -> '%s': %s", type, source, target,
+                    errorMessage));
+        }
+    }
+
+    //
+    // The wrappers for the native function calls.
+    //
+    
+    private static native int hardlink(String filename, String linktarget);
+
+    private static native int symlink(String filename, String linktarget);
+
+    private static native String strerror(int errnum);
+
+    /**
+     * Returns <code>true</code>, if the native library has been loaded successfully and the link
+     * utilities are operational, <code>false</code> otherwise.
+     */
+    public static final boolean isOperational()
+    {
+        return operational;
+    }
+
+    /**
+     * Creates a hard link from <var>filename</var> to <var>linktarget</var>.
+     * 
+     * @throws FileLinkException If the underlying system call fails, e.g. because <var>filename</var>
+     *             does not exist or because <var>linktarget</var> already exists.
+     */
+    public static final void createHardLink(String filename, String linktarget)
+            throws FileLinkException
+    {
+        final int result = hardlink(filename, linktarget);
+        if (result != 0)
+        {
+            throw new FileLinkException("hard", linktarget, filename, strerror(result));
+        }
+    }
+
+    /**
+     * Creates a symbolic link from <var>filename</var> to <var>linktarget</var>.
+     * 
+     * @throws FileLinkException If the underlying system call fails, e.g. because <var>filename</var>
+     *             does not exist or because <var>linktarget</var> already exists.
+     */
+    public static final void createSymbolicLink(String filename, String linktarget)
+            throws FileLinkException
+    {
+        final int result = symlink(filename, linktarget);
+        if (result != 0)
+        {
+            throw new FileLinkException("symbolic", linktarget, filename, strerror(result));
+        }
+    }
+
+}