#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>

int spawn(char *command, char **args)
{
	/* sample usage:
	 *	
	 *	char *args[3];
	 *	
	 *	args[0] = "sh";
	 *	args[1] = "/path/to/script";
	 *	args[2] = NULL;
	 *	spawn("/bin/sh", args);
	 */

	struct sigaction act, intr, quit;
	sigset_t block, oldmask;
	int status = -1;
	pid_t pid;

	sigemptyset(&act.sa_mask);
	act.sa_flags = SA_RESTART;

	act.sa_handler = SIG_IGN;
	if (sigaction(SIGINT, &act, &intr) < 0)
		goto error_1;
	if (sigaction(SIGQUIT, &act, &quit) < 0)
		goto error_2;

	sigemptyset(&block);
	sigaddset(&block, SIGCHLD);
	if (sigprocmask(SIG_BLOCK, &block, &oldmask) < 0)
		goto error_3;

	pid = fork();

	if (pid < 0)
	{
		fprintf(stderr, "unable to create a new process");
		goto error_4;
	}

	if (pid == 0)
	{
		sigaction(SIGINT, &intr, NULL);
		sigaction(SIGQUIT, &quit, NULL);

		execvp(command, args);
		/* if we reach this point, execvp() failed */
		fprintf(stderr, "unable to execute command");
		_exit(127);
	}
	else
	{
		pid_t n;

		do n = waitpid(pid, &status, 0);
		while (n == (pid_t) -1 && errno == EINTR);

		if (n != pid)
			status = -1;
	}

error_4:
	sigprocmask(SIG_SETMASK, &oldmask, NULL);
error_3:
	sigaction(SIGQUIT, &quit, NULL);
error_2:
	sigaction(SIGINT, &intr, NULL);
error_1:
	return status;
}