Linux signal Masking

<span style= "FONT-SIZE:18PX;" > #include <sys/types.h> #include <unistd.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <errno.h>/*sigemptyset (&newmask);//Get an empty shielded signal set Sigfillset (&newmask);// Gets the masked signal set that masks all the signals. In addition to the two Sigkill sigstopsigpending (&pendmask);//Gets the current set of masked signals in the process Sigaddset (&newmask, sigquit);//air shield signal set increased sigquit (Sigprocmask (Sig_block, &newmask, &oldmask) < 0)//Set (Sigprocmask (Sig_setmask, &oldmask, NULL) < 0)// Sets the original masked signal set (Sigismember (&fillmask, Sigquit))//infers whether Sigquit is in the current masked signal set */static voidsig_quit (int); Intmain (void) { Sigset_tnewmask, Oldmask, Pendmask,fillmask;if (Signal (sigquit, sig_quit) = = Sig_err)//Set signal processing function perror ("Can ' t catch Sigquit "),/* * Block sigquit and save current signal mask. */sigemptyset (&newmask);//Obtain an empty shielded signal set Sigaddset (&newmask, sigquit);//Add sigquitif to the empty shielded signal set (Sigprocmask (Sig_ BLOCK, &newmask, &oldmask) < 0)//Set Perror ("Sig_block error"), Sleep (5);/* Sigquit here'll remaiN Pending *///During sleep Press multiple ctrl+\ pending signal set hold once if (Sigpending (&pendmask) < 0)//Gets the current masked signal set in the process perror ("Sigpending Erro R "), if (Sigismember (&pendmask, Sigquit))//Infer whether Sigquit is in the current masking signal set printf (" \nsigquit pending\n ");/* * Restore signal Mask which unblocks sigquit. */if (Sigprocmask (Sig_setmask, &oldmask, NULL) < 0)//Set the original masked signal set. Because the sigquit retains a pending signal, the signal processing function is triggered here, and sigquit changes back to the default processing perror ("Sig_setmask error");p rintf ("Sigquit unblocked\n"); Sleep (5) ;/* Sigquit here would terminate with core file *////During this time press ctrl+\ to run the signal handler function and invoke the default processing. Game over! printf ("Fillmask test\n"), if (Sigfillset (&fillmask) < 0)//Gets a shielded signal set that masks all signals, except for those two Sigkill sigstopperror (" Sigfillset error\n "), if (Sigismember (&fillmask, Sigquit))//Infer whether Sigquit is in the current masked signal set printf (" \nsigquit pending\n ") ;//In If (Sigprocmask (Sig_setmask,&fillmask, &oldmask) < 0)//Set Mask all perror ("Fillmask error\n"); sleep (5); if ( Sigprocmask (Sig_setmask, &oldmask, NULL) < 0)//If you have pressed ctrl+\ during the Fillmask test. The following will not sleep for 5 seconds. The default handler for Sigquit is running Perror ("Sig_setmask error\n "); sleep (5); exit (0);} static voidsig_quit (int signo) {printf ("Caught sigquit\n"),//if (Signal (sigquit, SIG_DFL) = = Sig_err)//perror ("Can ' t Reset Sigquit ");} </span>

Linux signal Masking