code:issig - ikarishinjieva/unixV6-code-analyze-chs GitHub Wiki

3979

3980 /*

3981 * Returns true if the current

3982 * process has a signal to process.

3983 * This is asked at least once

3984 * each time a process enters the

3985 * system.

3986 * A signal does not do anything

3987 * directly to a process; it sets

3988 * a flag that asks the process to

3989 * do something to itself.

3990 */

3991 issig()

3992 {

3993 register n;

3994 register struct proc *p;

3995

3996 p = u.u_procp;

3997 if(n = p->p_sig) {

3998 if (p->p_flag&STRC) {

3999 stop();

现行进程带跟踪标志(STRC)，执行stop

参看跟踪

4000 if ((n = p->p_sig) == 0)

4001 return(0);

信号为 0，不做处理

4002 }

4003 if((u.u_signal[n]&1) == 0)

4004 return(n);

信号处理方式

为奇数，不做处理

为偶数，返回信号值

4005 }

4006 return(0);

4007 }

4008 /* ------------------------- */