mac os父进程单步调试子进程执行了多少条指令

#import <Foundation/Foundation.h>

#import <sys/ptrace.h>

#import <string.h>

void run_target(const char* programname)

{

    /* Allow tracing of this process */

    if (ptrace(PT_TRACE_ME, 0, 1, 0) < 0) {

        perror("ptrace");

        return;

    }

    /* Replace this process's image with the given program */

    printf("target started. will run '%s'\n", programname);

    execl(programname, programname, 0);

    char * error = strerror(errno);

    printf("error = %s",error);

}

 

 

 

void run_debugger(pid_t child_pid)

{

    int wait_status;

    unsigned icounter = 0;

    int wait_result = 0;

    printf("parent debugger started\n");

    /* Wait for child to stop on its first instruction */

    waitpid(child_pid, &wait_status, WUNTRACED);

    while (WIFSTOPPED(wait_status)) {

        printf("while start wait_status = %d\n",wait_status);

        icounter++;

        /* Make the child execute another instruction */

        int result = 0;

        result = ptrace(PT_STEP, child_pid, 1, 0);

        if (result < 0) {

            char * errstr = strerror(errno);

            printf("%s\n",errstr);

            return;

        }

        printf("run_debugger icounter=%d,result=%d\n",icounter,result);

        /* Wait for child to stop on its next instruction */

        //如果返回值为0,那么

        wait_result = waitpid(child_pid, &wait_status, WUNTRACED);

        if(wait_result != 0)

        {

            usleep(20);

        }

        printf("while end wait_result = %d\n",wait_result);

    }

    printf("the child executed %u instructions\n", icounter);

}

 

int main(int argc, char** argv)

{

    pid_t child_pid;

    if (argc < 2) {

        fprintf(stderr, "Expected a program name as argument\n");

        return -1;

    }

    child_pid = fork();

    if (child_pid == 0)

    {

        run_target(argv[1]);

    }

    else if (child_pid > 0)

    {

        run_debugger(child_pid);

    }

    else {

        perror("fork");

        return -1;

    }

    return 0;

}

 不知道为什么要usleep(20),不然就是一直wait,父进程和子进程都不能够退出！