More explanation

main.c

@@ -94,6 +94,9 @@ int main(int argc, const char** argv)
 
   if (pid != 0)
     {
+      /// Head process
+      // Wait for the init process in the PID namespace to terminate and forward its exit code.
+      // Also forward SIGTERM signals towards that init process.
 
       // Setup signal handler to forward SIGTERM
       pid_child = pid;
@@ -122,7 +125,17 @@ int main(int argc, const char** argv)
       pid = fork();
       if (pid != 0)
         {
-          // Init process wait for anything and exit if first child exits.
+          /// Init process
+          // This part of the program runs as first process in the pid namespace
+          // When this terminates then Linux terminates all remaining processes
+          // in the PID namespace. As we want this to happen when our first child
+          // terminates, we wait for our first child to terminate before terminating
+          // ourselves.
+          // As first process in the PID namespace, this also functions as adopting parent
+          // for orphaned processes in the PID namespace and therefore has to wait for
+          // any child process and then check if the a child process that has terminated
+          // is the one we were waiting for.
+
           pid_t first_child = pid;
           pid_t exited_child;
           int child_status;