Linux reliable/unreliable signal programming practice

Comprehensive Case

1) Create child process and parent process;

2) Register SIGINT non-real-time signal and sigrtmin real-time signal, and add these two signals to the process shielding signal Group;

3) Register user-defined signals;

4) The sub-process sends 5 non-real-time signals and sends 5 real-time signals;

5) The sub-process then sends the SIGUSR1 to unblock the sigint,sigtrmin signal.

6) Observe the difference between real-time and non-real-time signals

program example void onsigaction (int signalnumber, siginfo_t *siginfostruct, void *) {//Get received data int receivenumber = Siginfost    ruct->si_int;        If the SIGUSR1 signal is received, the Sigint,sigrtmin shield if (signalnumber = = SIGUSR1) {sigset_t unblockset is lifted;        Sigemptyset (&unblockset);        Sigaddset (&unblockset,sigint);        Sigaddset (&unblockset,sigrtmin);        Sigprocmask (Sig_unblock,&unblockset,null);        Value will be garbled!        cout << "Receive SIGUSR1, Value =" << receivenumber << Endl;    cout << "Unblock, Receive SIGUSR1" << Endl;  } else if (Signalnumber = = SIGINT) {cout << Receive SIGINT, Value = "<< receivenumber <<    Endl } else if (Signalnumber = = sigrtmin) {cout << Receive sigrtmin, Value = "<< Receivenumber <    < Endl;    }}//error exit Function inline void Err_exit (string str); int main () {struct Sigaction act; If you need to allow the signal handler to receive additional data,//the sa_flags position must be sa_siGinfo act.sa_flags = Sa_siginfo;    Sigemptyset (&act.sa_mask);    Act.sa_sigaction = onsigaction;    Register Signal Processing function if (sigaction (Sigint,&act,null) < 0) Err_exit ("Sigaction SIGINT");    if (Sigaction (Sigrtmin,&act,null) < 0) Err_exit ("Sigaction sigrtmin");    if (Sigaction (Sigusr1,&act,null) < 0) Err_exit ("Sigaction SIGUSR1");    Blocking the signal sigint,sigrtmin signal sigset_t blockSet;    Sigemptyset (&blockset);    Sigaddset (&blockset,sigint);    Sigaddset (&blockset,sigrtmin);    if (Sigprocmask (Sig_block,&blockset,null) < 0) err_exit ("Sigprocmask error");    pid_t pid = fork ();    if (PID = =-1) err_exit ("fork Error");        else if (PID = = 0) {Union sigval Value;        Value.sival_int = 200;            Send a non-reliable signal to the parent process five times with extra data (in fact only once) for (int i = 0; i < 5; ++i) {+ + Value.sival_int; if (Sigqueue (Getppid (), sigint,value)! = 0) err_exit ("Sigqueue error");       }//sends a reliable signal to the parent process five times with additional data (five last received!!!)        Value.sival_int = 0;            for (int i = 0; i < 5; ++i) {+ + Value.sival_int;        if (Sigqueue (Getppid (), sigrtmin,value)! = 0) err_exit ("Sigqueue error");    }//sends a SIGUSR1 signal to the parent process, lifting the sigint,sigrtmin signal blocking Kill (Getppid (), SIGUSR1);    } while (true) {pause ();    }}void err_exit (String str) {perror (Str.c_str ()); Exit (exit_failure);}

Operation result :

Actually, I just received a non-reliable signal sigint!

Attached-View System restrictions command: Ulimit

[Email protected]:~$ ulimit-acore File size          (blocks,-c) unlimiteddata seg size           (Kbytes,-D) unlimitedscheduling Priority             (-e) 0file size               (blocks,-f) unlimitedpending signals (-I                 ) 47131max locked memory       (Kbytes, L) 64max Memory Size         (Kbytes,-m) unlimitedopen files                      (-N) 1024pipe size            (bytes,-p) 8POSIX message Queues
    (bytes,-Q) 819200real-time priority              (-R) 0stack size              (Kbytes,-s) 8192cpu time               (seconds,-t) Unlimitedmax User Processes              (-u) 47131virtual memory          (Kbytes,-V) unlimitedfile locks                      (-X) Unlimited

Linux reliable/unreliable signal programming practice