From 1c568045e853765174c744023a72afaecf8293eb Mon Sep 17 00:00:00 2001
From: Vahagn Khachatryan <vkhachat@mentor.com>
Date: Tue, 3 Mar 2015 11:33:36 +0400
Subject: [PATCH] Also stop/continue SIGTERM/SIGKILL are tested.

---
 linux/fork_wait_exit_status.cpp | 113 +++++++++++++++++++++++---------
 1 file changed, 81 insertions(+), 32 deletions(-)

diff --git a/linux/fork_wait_exit_status.cpp b/linux/fork_wait_exit_status.cpp
index f1c332b..821ca63 100644
--- a/linux/fork_wait_exit_status.cpp
+++ b/linux/fork_wait_exit_status.cpp
@@ -7,6 +7,7 @@ VIM-: let g:ldlibpath=g:Bboost.g:Btbb
 VIM: let g:argv=""
 */
 #include <unistd.h>
+#include <signal.h>
 #include <sys/wait.h>
 
 #include <iostream>
@@ -16,29 +17,31 @@ VIM: let g:argv=""
 #define WCOREDUMP(status) (0)
 #endif
 
-void pr_exit(int status)
-{
-	if (WIFEXITED(status))
-		std::cout << "normal termination, exit status =" 
-					<<  WEXITSTATUS(status) << std::endl;
-	else if (WIFSIGNALED(status))
-		std::cout << "abnormal termination, signal number = " 
-					<< WTERMSIG(status)
-					<< (WCOREDUMP(status) ? " (core file generated)" : "")
-					<< std::endl;
-	else if (WIFSTOPPED(status))
-		std::cout << "child stopped, signal number = "
-					<<  WSTOPSIG(status) << std::endl;
-}
-
-template< class F>
-void fork_and_wait( const char * caption, F&& f )
+void print_status(const char * caption, int status)
 {
 	std::cout << caption << ": ";
 	std::cout.flush();
 
+	if (WIFEXITED(status))
+		std::cout << "normal termination, exit status = " << WEXITSTATUS(status);
+	else if (WIFSIGNALED(status))
+		std::cout << "abnormal termination, signal number = " 
+					<< WTERMSIG(status)
+					<< (WCOREDUMP(status) ? " (core file generated)" : "");
+	else if (WIFSTOPPED(status))
+		std::cout << "child stopped, signal number = " <<  WSTOPSIG(status);
+	else if (WIFCONTINUED(status))
+		std::cout << "child continued";
+	else
+		std::cout << "couldn't figure our exit reason. status = " << status;
+	std::cout << std::endl;
+	std::cout.flush();
+}
+
+template< class F>
+pid_t fork_lambda( F&& f )
+{
 	pid_t pid;
-	int status;
 	if ((pid = fork()) < 0)
 		throw std::runtime_error("fork error");
 	else if (pid == 0) /* child */
@@ -47,28 +50,74 @@ void fork_and_wait( const char * caption, F&& f )
 		exit(0);
 	}
 	else/*parent*/
-	{
-		if (wait(&status) != pid) /* wait for child */
-			throw std::runtime_error("wait	error");
-		pr_exit(status); /* and print its status */
-	}
+		return pid;
+}
+
+int wait_for_status( pid_t pid )
+{
+	int status;
+	if (waitpid(pid,&status,WUNTRACED|WCONTINUED) != pid)
+		throw std::runtime_error("wait	error");
+	return status;
 }
 
 void test()
 {
-	fork_and_wait("exit(7)", [](){
-			exit(7);
+	pid_t pid;
+	//
+	//	Normal exit.
+	//
+	pid = fork_lambda([](){
+		exit(7);
 	});
+	print_status( "exit(7)", wait_for_status(pid) );
+	//
+	//	Self aborting process.
+	//
+	pid = fork_lambda([](){
+		abort();
+	});
+	print_status( "SIGABORT through abort()", wait_for_status(pid) );
 
-	fork_and_wait("SIGABORT through abort()", [](){
-			abort();
+	//
+	//	Raise SIGFPE.
+	//
+	pid = fork_lambda([](){
+		volatile int a = rand();
+		int b = 0;
+		a /= b;
 	});
-	
-	fork_and_wait("SIGFPE through divison by zero", [](){
-			int a = rand();
-			int b = 0;
-			a /= b;
+	print_status( "SIGFPE through division by zero", wait_for_status(pid) );
+	//
+	//	Kill process.
+	//
+	pid = fork_lambda([](){
+		while ( true );
 	});
+	if (kill( pid, SIGKILL ))
+		throw std::runtime_error("failed to send kill signal");
+	print_status( "SIGKILL is sent", wait_for_status(pid) );
+	//
+	//	Stop process.
+	//
+	pid = fork_lambda([](){
+		while ( true );
+	});
+	if (kill( pid, SIGSTOP ))
+		throw std::runtime_error("failed to send stop signal");
+	print_status( "SIGSTOP is sent", wait_for_status(pid) );
+	//
+	//	Resume process.
+	//
+	if (kill( pid, SIGCONT ))
+		throw std::runtime_error("failed to send continue signal");
+	print_status( "SIGCONT is sent", wait_for_status(pid) );
+	//
+	//	Terminate process.
+	//
+	if (kill( pid, SIGTERM ))
+		throw std::runtime_error("failed to send termination signal");
+	print_status( "SIGTERM is sent", wait_for_status(pid) );
 }
 
 int main ( void )