1 Alarm Signals and SIGALRM

1.1 Setting an alarm

unsigned int alarm(unsigned int seconds);
过n秒后向进程发送SIGALARM信号
SIGALARM信号默认动作是terminate

#include <stdio.h>
#include <stdlib.h>#include <unistd.h>
#include <signal.h>
#include <sys/signal.h>void alarm_handler(int signum){printf("Buzz Buzz Buzz\n");
}int main(){//set up alarm handlersignal(SIGALRM, alarm_handler);//schedule alarm for 1 secondalarm(1);//do not proceed until signal is handledpause();}

1.2 Recurring Alarms

/* buzz_buzz.c*/void alarm_handler(int signum){printf("Buzz Buzz Buzz\n");//set a new alarm for 1 secondalarm(1);}int main(){//set up alarm handlersignal(SIGALRM, alarm_handler);//schedule the first alarmalarm(1);//pause in a loopwhile(1){pause();}}

1.3 Resetting Alarms

void sigint_handler(int signum){printf("Snoozing!\n");//schedule next alarm for 5 secondsalarm(5);
}void alarm_handler(int signum){printf("Buzz Buzz Buzz\n");//set a new alarm for 1 secondalarm(1);
}int main(){//set up alarm handlersignal(SIGALRM, alarm_handler);//set up signint handlersignal(SIGINT, sigint_handler);//schedule the first alarmalarm(1);//pause in a loopwhile(1){pause();}}

2 sigaction() and Reentrant Functions

2.1 sigaction()

1.int sigaction(int signum, const struct sigaction *act,struct sigaction *oldact);
2.

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

void handler(int signum){printf("Hello World!\n");
}int main(){//declare a struct sigactionstruct sigaction action;//set the handleraction.sa_handler = handler;//call sigaction with the action structuresigaction(SIGALRM, &action, NULL);//schedule an alarmalarm(1);//pausepause();
}

2.2 Reentrant Functions

2.3 Interrupting System call EINTR

2.4 SA_RESTART

2.5 Not all System Calls are Reentrant

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20 Alarms, sigaction(), and Reentrant System Calls

1 Alarm Signals and SIGALRM

1.1 Setting an alarm

1.2 Recurring Alarms

1.3 Resetting Alarms

2 sigaction() and Reentrant Functions

2.1 sigaction()

2.2 Reentrant Functions

2.3 Interrupting System call EINTR

2.4 SA_RESTART

2.5 Not all System Calls are Reentrant

20 Alarms, sigaction(), and Reentrant System Calls相关推荐

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