[JENKINS-9118]

Tar/untar now correctly supports symlinks.

core/src/main/java/hudson/FilePath.java

@@ -46,8 +46,9 @@ import hudson.util.IOException2;
 import hudson.util.HeadBufferingStream;
 import hudson.util.FormValidation;
 import hudson.util.IOUtils;
+
+import static hudson.Util.*;
 import static hudson.util.jna.GNUCLibrary.LIBC;
-import static hudson.Util.fixEmpty;
 import static hudson.FilePath.TarCompression.GZIP;
 import hudson.org.apache.tools.tar.TarInputStream;
 import hudson.util.io.Archiver;
@@ -75,6 +76,7 @@ import java.io.OutputStream;
 import java.io.Serializable;
 import java.io.Writer;
 import java.io.OutputStreamWriter;
+import java.lang.reflect.Field;
 import java.net.URI;
 import java.net.URL;
 import java.net.URLConnection;
@@ -331,6 +333,15 @@ public final class FilePath implements Serializable {
         zip(os,(FileFilter)null);
     }
 
+    public void zip(FilePath dst) throws IOException, InterruptedException {
+        OutputStream os = dst.write();
+        try {
+            zip(os);
+        } finally {
+            os.close();
+        }
+    }
+    
     /**
      * Creates a zip file from this directory by using the specified filter,
      * and sends the result to the given output stream.
@@ -529,6 +540,39 @@ public final class FilePath implements Serializable {
         }));
     }
 
+    /**
+     * Creates a symlink to the specified target.
+     *
+     * @param target
+     *      The file that the symlink should point to.
+     * @param listener
+     *      If symlink creation requires a help of an external process, the error will be reported here.
+     * @since 1.456
+     */
+    public void symlinkTo(final String target, final TaskListener listener) throws IOException, InterruptedException {
+        act(new FileCallable<Void>() {
+            public Void invoke(File f, VirtualChannel channel) throws IOException, InterruptedException {
+                Util.createSymlink(f.getParentFile(),target,f.getName(),listener);
+                return null;
+            }
+        });
+    }
+    
+    /**
+     * Resolves symlink, if the given file is a symlink. Otherwise return null.
+     * <p>
+     * If the resolution fails, report an error.
+     *
+     * @since 1.456
+     */
+    public String readLink() throws IOException, InterruptedException {
+        return act(new FileCallable<String>() {
+            public String invoke(File f, VirtualChannel channel) throws IOException, InterruptedException {
+                return Util.resolveSymlink(f);
+            }
+        });
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
@@ -1756,7 +1800,13 @@ public final class FilePath implements Serializable {
                     File parent = f.getParentFile();
                     if (parent != null) parent.mkdirs();
 
-                    IOUtils.copy(t,f);
+                    byte linkFlag = (Byte) LINKFLAG_FIELD.get(te);
+                    if (linkFlag==TarEntry.LF_SYMLINK) {
+                        new FilePath(f).symlinkTo(te.getLinkName(), TaskListener.NULL);
+                    } else {
+                        IOUtils.copy(t,f);
+                    }
+                    
                     f.setLastModified(te.getModTime().getTime());
                     int mode = te.getMode()&0777;
                     if(mode!=0 && !Functions.isWindows()) // be defensive
@@ -1765,6 +1815,11 @@ public final class FilePath implements Serializable {
             }
         } catch(IOException e) {
             throw new IOException2("Failed to extract "+name,e);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt(); // process this later
+            throw new IOException2("Failed to extract "+name,e);
+        } catch (IllegalAccessException e) {
+            throw new IOException2("Failed to extract "+name,e);
         } finally {
             t.close();
         }
@@ -2124,4 +2179,18 @@ public final class FilePath implements Serializable {
             return o1.length()-o2.length();
         }
     };
+
+    private static final Field LINKFLAG_FIELD = getTarEntryLinkFlagField();
+
+    private static Field getTarEntryLinkFlagField() {
+        try {
+            Field f = TarEntry.class.getDeclaredField("linkFlag");
+            f.setAccessible(true);
+            return f;
+        } catch (SecurityException e) {
+            throw new AssertionError(e);
+        } catch (NoSuchFieldException e) {
+            throw new AssertionError(e);
+        }
+    }
 }