技术解析
之前一直通过pthread_kill向指定线程发送信号，但后来将系统调用system换成了如下的实现：
long ___system(const char *pcStr)
{
int status;
int pid;
char tmpstack[SYSTEM_STACKSIZE];
void **newstack;
newstack = (void **)(void *)(ULONG) (SYSTEM_STACKSIZE + tmpstack);
*--newstack = (void *)pcStr;
pid = clone(__system_proc, newstack,
CLONE_VM | CLONE_FS | SIGCHLD, (void *)pcStr);
if (pid < 0)
{
printf("clone() failed! errno = %d[%s]\n", errno, strerror(errno));
return -1;
}
(void)waitpid(pid, &status, __WALL /*__WCLONE*/);
return status;