Fix interruption handling in nested shells

This change modifies the Shell.sh method to properly handle interruption signals
in nested shells by clearing and restoring the current pipe. When a user starts a
shell session, then runs the 'sh' command to create a nested shell, and then runs
a command like 'ttop' in that nested shell, pressing Ctrl+C now properly interrupts
the command.

This complements PR #411 which made the Pipe.setCurrentPipe method public to enable
this fix. Together, these changes resolve the issue reported in jline/jline3#1143
where interruption exceptions were not working for child sessions.

The fix follows the same pattern implemented in the Posix.runShell method, ensuring
consistent behavior across different shell creation methods.

Author: gnodet

gogo/jline/pom.xml

@@ -58,7 +58,7 @@
         <dependency>
             <groupId>org.apache.felix</groupId>
             <artifactId>org.apache.felix.gogo.runtime</artifactId>
-            <version>1.1.0</version>
+            <version>1.1.7-SNAPSHOT</version>
         </dependency>
         <dependency>
             <groupId>org.apache.felix</groupId>

gogo/jline/src/main/java/org/apache/felix/gogo/jline/Posix.java

@@ -71,6 +71,7 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import org.apache.felix.gogo.runtime.Pipe;
 import org.apache.felix.service.command.Process;
 import org.apache.felix.gogo.jline.Shell.Context;
 import org.apache.felix.service.command.CommandProcessor;
@@ -811,6 +812,10 @@ private void startShell(CommandSession session, Terminal terminal) {
     private void runShell(CommandSession session, Terminal terminal) {
         InputStream in = terminal.input();
         OutputStream out = terminal.output();
+        
+        // Save the current pipe and clear it before creating a child shell
+        Pipe currentPipe = Pipe.setCurrentPipe(null);
+
         CommandSession newSession = processor.createSession(in, out, out);
         newSession.put(Shell.VAR_TERMINAL, terminal);
         newSession.put(".tmux", session.get(".tmux"));
@@ -822,11 +827,26 @@ public void exit() throws Exception {
                 terminal.close();
             }
         };
+
+        // Register a signal handler for INT signal to properly propagate interruption
+        Terminal.SignalHandler prevIntHandler = terminal.handle(Terminal.Signal.INT, signal -> {
+            // Propagate the interrupt to the current thread
+            Thread.currentThread().interrupt();
+        });
+        
         try {
-            new Shell(context, processor).gosh(newSession, new String[]{"--login"});
+            new Shell(context, processor).gosh(newSession, new String[] {"--login"});
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
+            // Restore the previous signal handler
+            if (prevIntHandler != null) {
+                terminal.handle(Terminal.Signal.INT, prevIntHandler);
+            }
+            
+            // Restore the previous pipe
+            Pipe.setCurrentPipe(currentPipe);
+
             try {
                 terminal.close();
             } catch (IOException e) {

gogo/jline/src/main/java/org/apache/felix/gogo/jline/Shell.java

@@ -46,6 +46,7 @@
 import org.apache.felix.gogo.runtime.Closure;
 import org.apache.felix.gogo.runtime.CommandProxy;
 import org.apache.felix.gogo.runtime.CommandSessionImpl;
+import org.apache.felix.gogo.runtime.Pipe;
 import org.apache.felix.service.command.Job;
 import org.apache.felix.service.command.Job.Status;
 import org.apache.felix.gogo.runtime.Reflective;
@@ -440,6 +441,16 @@ private CommandSession createChildSession(CommandSession parent) {
 
     private Object runShell(final CommandSession session, Terminal terminal,
                             LineReader reader) throws InterruptedException {
+        Pipe currentPipe = Pipe.setCurrentPipe(null);
+        try {
+            return doRunShell(session, terminal, reader);
+        } finally {
+            Pipe.setCurrentPipe(currentPipe);
+        }
+    }
+
+    private Object doRunShell(final CommandSession session, Terminal terminal,
+                            LineReader reader) throws InterruptedException {
         AtomicBoolean reading = new AtomicBoolean();
         session.setJobListener((job, previous, current) -> {
             if (previous == Status.Background || current == Status.Background
@@ -555,7 +566,15 @@ private String getStatusLine(Job job, int width, String status) {
 
     @Descriptor("start a new shell")
     public Object sh(final CommandSession session, String[] argv) throws Exception {
-        return gosh(session, argv);
+        // Save the current pipe and clear it before creating a child shell
+        // This ensures that interruption signals are properly propagated to the child shell
+        Pipe currentPipe = Pipe.setCurrentPipe(null);
+        try {
+            return gosh(session, argv);
+        } finally {
+            // Restore the previous pipe
+            Pipe.setCurrentPipe(currentPipe);
+        }
     }
 
     private void shutdown() throws Exception {