细说linux IPC（八）：信号（下）

       #include <signal.h>
       int sigqueue(pid_t pid, int sig, const union sigval value);

           union sigval {
               int sival_int;
               void *sival_ptr;
           };

       #include <signal.h>
       int sigaction(int signum, const struct sigaction *act,  struct sigaction *oldact);

           struct sigaction {
               void (*sa_handler)(int);
               void (*sa_sigaction)(int, siginfo_t *, void *);
               sigset_t sa_mask;
               int sa_flags;
               void (*sa_restorer)(void);
           };

           siginfo_t {
               int si_signo; /* Signal number */
               int si_errno; /* An errno value */
               int si_code; /* Signal code */
               int si_trapno; /* Trap number that causedhardware-generated signal(unused on most architectures) */
               pid_t si_pid; /* Sending process ID */
               uid_t si_uid; /* Real user ID of sending process */
               int si_status; /* Exit value or signal */
               clock_t si_utime; /* User time consumed */
               clock_t si_stime; /* System time consumed */
               sigval_t si_value; /* Signal value */
               int si_int; /* POSIX.1b signal */
               void *si_ptr; /* POSIX.1b signal */
               int si_overrun; /* Timer overrun count; POSIX.1b timers */
               int si_timerid; /* Timer ID; POSIX.1b timers */
               void *si_addr; /* Memory location which caused fault */
               long si_band; /* Band event (was int in glibc 2.3.2 and earlier) */
               int si_fd; /* File descriptor */
               short si_addr_lsb; /* Least significant bit of address since Linux 2.6.32) */
           }

void sig_func(int signo, siginfo_t *info, void *arg)
{
// sleep(6);
    printf("====%s== [child] handle signo: %d==arg: %d=\n", __func__, signo, info->si_int);
}
void child_process_do(void)
{
    struct sigaction act;
    printf("====%s==child pid: %d===\n", __func__, getpid());
    //signal(SIGRTMIN, sig_func);
    //signal(SIGALRM, sig_func);
    act.sa_sigaction = sig_func;
    act.sa_flags = SA_SIGINFO;
    if (sigaction(SIGALRM, &act, NULL) < 0) { //此处安装信号处理函数
        fprintf(stderr, "sigaction: %s\n", strerror(errno));
        return;
    }
    while (1) {
        sleep(10);
    }
}
void parent_process_do(pid_t pid)
{
    int i, val = 100;
    union sigval sigarg;
    sleep(1);
    printf("====%s==parent pid: %d===\n", __func__, getpid());
    for (i = 0; i < 5; i++) {
        printf("====%s==[parent] send signal <%d> to pid <%d>==\n", __func__, SIGRTMIN, pid);
        //kill(pid, SIGRTMIN);
        //kill(pid, SIGALRM);
        sigarg.sival_int = val + i;
        sigqueue(pid, SIGALRM, sigarg); //此处发送SIGALRM信号，sigarg为要传送的参数
        sleep(1);
    }
    waitpid(pid, NULL, 0);
}
int main(int argc, const char *argv[])
{
    pid_t pid;
    pid = fork();
    if (pid < 0) {
        fprintf(stderr, "fork: %s\n", strerror(errno));
        return -1;
    }
    if (0 == pid) {
        child_process_do();
    } else {
        parent_process_do(pid);
    }
    return 0;
}