added a hook for decorating launchers

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@16994 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/Launcher.java

@@ -28,6 +28,7 @@ import hudson.Proc.RemoteProc;
 import hudson.model.Computer;
 import hudson.model.Hudson;
 import hudson.model.TaskListener;
+import hudson.model.Node;
 import hudson.remoting.Callable;
 import hudson.remoting.Channel;
 import hudson.remoting.Pipe;
@@ -325,6 +326,60 @@ public abstract class Launcher {
         printCommandLine(masked, workDir);
     }
 
+    /**
+     * Returns a decorated {@link Launcher} for the given node.
+     */
+    public final Launcher decorateFor(Node node) {
+        Launcher l = this;
+        for (LauncherDecorator d : LauncherDecorator.all())
+            l = d.decorate(l,node);
+        return l;
+    }
+
+    /**
+     * Returns a decorated {@link Launcher} that puts the given set of arguments as a prefix to any commands
+     * that it invokes.
+     *
+     * @since 1.299
+     */
+    public final Launcher decorateByPrefix(final String... prefix) {
+        final Launcher outer = this;
+        return new Launcher(listener,channel) {
+            @Override
+            public Proc launch(String[] cmd, String[] env, InputStream in, OutputStream out, FilePath workDir) throws IOException {
+                return outer.launch(prefix(cmd),env,in,out,workDir);
+            }
+
+            @Override
+            public Proc launch(String[] cmd, boolean[] mask, String[] env, InputStream in, OutputStream out, FilePath workDir) throws IOException {
+                return outer.launch(prefix(cmd),prefix(mask),env,in,out,workDir);
+            }
+
+            @Override
+            public Channel launchChannel(String[] cmd, OutputStream out, FilePath workDir, Map<String, String> envVars) throws IOException, InterruptedException {
+                return outer.launchChannel(prefix(cmd),out,workDir,envVars);
+            }
+
+            @Override
+            public void kill(Map<String, String> modelEnvVars) throws IOException, InterruptedException {
+                outer.kill(modelEnvVars);
+            }
+
+            private String[] prefix(String[] args) {
+                String[] newArgs = new String[args.length+prefix.length];
+                System.arraycopy(prefix,0,newArgs,0,prefix.length);
+                System.arraycopy(args,0,newArgs,prefix.length,args.length);
+                return newArgs;
+            }
+
+            private boolean[] prefix(boolean[] args) {
+                boolean[] newArgs = new boolean[args.length+prefix.length];
+                System.arraycopy(args,0,newArgs,prefix.length,args.length);
+                return newArgs;
+            }
+        };
+    }
+
     /**
      * {@link Launcher} that launches process locally.
      */

core/src/main/java/hudson/LauncherDecorator.java

+package hudson;
+
+import hudson.model.Hudson;
+import hudson.model.Node;
+import hudson.model.TaskListener;
+import hudson.model.AbstractBuild;
+import hudson.model.BuildListener;
+import hudson.model.Executor;
+import hudson.tasks.BuildWrapper;
+
+/**
+ * Decorates {@link Launcher} so that one can intercept executions of commands
+ * and alters the command being executed, such as doing this in fakeroot, sudo, pfexec, etc.
+ *
+ * @author Kohsuke Kawaguchi
+ * @since 1.299
+ * @see BuildWrapper#decorateLauncher(AbstractBuild, Launcher, BuildListener)
+ */
+public abstract class LauncherDecorator implements ExtensionPoint {
+    /**
+     * Called from {@link Node#createLauncher(TaskListener)} to decorate the launchers.
+     *
+     * <p>
+     * This method should perform node-specific decoration. For job-specific decoration,
+     * {@link BuildWrapper#decorateLauncher(AbstractBuild, Launcher, BuildListener)} might
+     * fit your needs better.
+     *
+     * <p>
+     * If the implementation wants to do something differently if the launcher is
+     * for a build, call {@link Executor#currentExecutor()}. If it returns non-null
+     * you can figure out the current build in progress from there. Note that
+     * {@link Launcher}s are also created for doing things other than builds,
+     * so {@link Executor#currentExecutor()} may return null. Also, for job-specific
+     * decoration, see {@link BuildWrapper#decorateLauncher(AbstractBuild, Launcher, BuildListener)} as well.
+     *
+     * @param launcher
+     *      The base launcher that you can decorate. Never null.
+     * @param node
+     *      Node for which this launcher is created. Never null.
+     * @return
+     *      Never null. Return the 'launcher' parameter to do no-op.
+     * @see Launcher#decorateFor(Node)
+     * @see Launcher#decorateByPrefix(String[])
+     */
+    public abstract Launcher decorate(Launcher launcher, Node node);
+
+    /**
+     * Returns all the registered {@link LauncherDecorator}s.
+     */
+    public static ExtensionList<LauncherDecorator> all() {
+        return Hudson.getInstance().getExtensionList(LauncherDecorator.class);
+    }
+}

core/src/main/java/hudson/model/Hudson.java

@@ -44,6 +44,7 @@ import hudson.ExtensionList;
 import hudson.ExtensionPoint;
 import hudson.DescriptorExtensionList;
 import hudson.ExtensionListView;
+import hudson.LauncherDecorator;
 import hudson.logging.LogRecorderManager;
 import hudson.lifecycle.Lifecycle;
 import hudson.model.Descriptor.FormException;
@@ -891,7 +892,7 @@ public final class Hudson extends Node implements ItemGroup<TopLevelItem>, Stapl
     }
 
     public Launcher createLauncher(TaskListener listener) {
-        return new LocalLauncher(listener);
+        return new LocalLauncher(listener).decorateFor(this);
     }
 
     private final transient Object updateComputerLock = new Object();

core/src/main/java/hudson/model/Node.java

@@ -93,6 +93,9 @@ public abstract class Node extends AbstractModelObject implements Describable<No
 
     /**
      * Returns a {@link Launcher} for executing programs on this node.
+     *
+     * <p>
+     * The callee must call {@link Launcher#decorateFor(Node)} before returning to complete the decoration. 
      */
     public abstract Launcher createLauncher(TaskListener listener);
 

core/src/main/java/hudson/model/Slave.java

@@ -377,7 +377,7 @@ public abstract class Slave extends Node implements Serializable {
 
     public Launcher createLauncher(TaskListener listener) {
         SlaveComputer c = getComputer();
-        return new RemoteLauncher(listener, c.getChannel(), c.isUnix());
+        return new RemoteLauncher(listener, c.getChannel(), c.isUnix()).decorateFor(this);
     }
 
     /**

core/src/main/java/hudson/tasks/BuildWrapper.java

@@ -27,6 +27,7 @@ import hudson.ExtensionPoint;
 import hudson.Launcher;
 import hudson.DescriptorExtensionList;
 import hudson.FileSystemProvisionerDescriptor;
+import hudson.LauncherDecorator;
 import hudson.model.AbstractBuild;
 import hudson.model.Build;
 import hudson.model.BuildListener;
@@ -168,6 +169,7 @@ public abstract class BuildWrapper implements ExtensionPoint, Describable<BuildW
      *      If a fatal error is detected but the implementation handled it gracefully, throw this exception
      *      to suppress stack trace.
      * @since 1.280
+     * @see LauncherDecorator
      */
     public Launcher decorateLauncher(AbstractBuild build, Launcher launcher, BuildListener listener) throws IOException, InterruptedException, RunnerAbortedException {
         return launcher;