#include <stdio.h>
#include <string.h>	/* memset */
#include <setjmp.h>
#include <signal.h>
#include <stdlib.h>	/* exit */
#include <unistd.h>	/* execl */


#include <sys/mman.h>	/* mmap */
#include <sys/types.h>	/* open */
#include <sys/stat.h>	/* open */
#include <fcntl.h>	/* open */


#include <sys/ptrace.h>


#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>

#include <sys/user.h>


#include <errno.h>


pid_t wait3(int *status, int options, struct rusage *rusage);


struct user_regs_struct regs;


#define MUST(X) { if (!(X)) { fprintf(stderr, "FAILURE AT %s:%d\n", __FILE__, __LINE__ ); perror("perror"); exit(13); } }




int main()
{
	int pid = fork();

	if ( pid ) {
		// parent

		while (1) {

			int status= 0;
			int e = wait4( pid, &status, 0, NULL );
			fprintf(stderr, "waited for pid %d got %d status %d\n", pid, e, status );

			e= ptrace( PTRACE_GETREGS, pid, NULL, &regs );
			fprintf(stderr, "got regs e=%d pc=%ld\n", e, regs.eip );

			e= ptrace( PTRACE_SINGLESTEP, pid, NULL, 0 );
			//e= ptrace( PTRACE_SYSCALL, pid, NULL, 0 );
			fprintf(stderr, "stepped e=%d/%d pc=%ld\n", e, errno, regs.eip );

		}
		

	} else {
		// child

		long x= ptrace( PTRACE_TRACEME, 0, NULL, NULL );

		execl( "/bin/ls", "ls", NULL);

	}

	return 0;
}