代码1
#include
#include
#include
static void sig_usr(int);
int main()
{
if(signal(SIGUSR1,sig_usr)==SIG_ERR) printf("can't catch SIGNUSR1");
if(signal(SIGUSR2,sig_usr)==SIG_ERR) printf("cant catch SIGUSR2");
for(;;) pause();
}
static void sig_usr(int signo)
{
if(signo==SIGUSR1) printf("received SIGUSR1");
else if(signo==SIGUSR2) printf("received SIGUSR2");
else printf("received signal %d\n",signo);
return;
}
输出：
[matcha-vanilla@localhost test]$ ./a.out &
[3] 15636
[matcha-vanilla@localhost test]$ kill -USR2 15636
[matcha-vanilla@localhost test]$ kill 15636
[matcha-vanilla@localhost test]$ ./a.out &
[4] 15659
[3] Terminated ./a.out
[matcha-vanilla@localhost test]$
在新号处理程序中调用不可重用函数
#include
#include
#include
#include
static void my_alarm(int);
int main()
{
struct passwd *ptr;
signal(SIGALRM,my_alarm);
alarm(1);
for(;;)
{
if((ptr=getpwnam("matcha-vanilla"))==NULL) printf(
"getpwnam error\n");
if(strcmp(ptr->pw_name,"matcha-vanilla")!=0) printf("returun value corrupted!,pw_name=%s\n",ptr->pw_name);
}
}
static void my_alarm(int signo)
{
struct passwd *rootptr;
printf("insignal handler\n");
if((rootptr=getpwnam("root"))==NULL) printf("getpwnam(root) error");
alarm(1);
return;
}
sigcld处理
#include
#include
#include
#include
#include
static void sig_cld();
int main()
{
pid_t pid;
if(signal(SIGCLD,sig_cld)==-1) printf("signal error\n");
if((pid=fork())<0) printf("fork error\n");
else if(pid==0)
{
sleep(2);
_exit(0);
}
pause();
exit(0);
}
static void sig_cld()
{
pid_t pid;
int status;
printf("SIGCLD received\n");
if(signal(SIGCLD,sig_cld)==-1) printf("signal error\n");
if((pid=wait(&status))<0) printf("wait error\n");
printf("pid=%d\n",pid);
return;
}
sleep 的简单实现版本
#include
#include
#include
#include
#include
#include
static void sig_alrm(int signo)
{
return;
}
unsigned int sleep1(unsigned int nsecs)
{
if(signal(SIGALRM,sig_alrm)==SIG_ERR) return(nsecs);
alarm(nsecs);
pause();
return (alarm(0));
}
int main()
{
sleep1(100);
}
另一版本
#include
#include
#include
#include
#include
#include
#include
static jmp_buf env_alrm;
static void sig_alrm(int signo)
{
longjmp(env_alrm,1);
}
unsigned int sleep2(unsigned int nsecs)
{
if(signal(SIGALRM,sig_alrm)==SIG_ERR) return(nsecs);
if(setjmp(env_alrm)==0)
{
alarm(nsecs);
pause();
}
return (alarm(0));
}
int main()
{
sleep2(10);
}
三
#include
#include
#include
#include
#include
#include
#include
unsigned int sleep2(unsigned int);
static void sig_int(int);
int main()
{
unsigned int unslept;
if(signal(SIGINT,sig_int)==SIG_ERR) printf("signal (SIGINT) error\n");
unslept=sleep(5);
printf("sleep2 returned:%u\n",unslept);
exit(0);
}
static void sig_int(int signo)
{
int i;
volatile int j;
printf("\nsig_int starting\n");
for(i=0;i<200000;i++) j+=i*i;
printf("sig_int finished\n"); return;
}
限定时间读写
#include
#include
#include
#include
#include
#include
#include
static void sig_alrm(int);
int main()
{
int n;
char line[100];
if(signal(SIGALRM,sig_alrm)==SIG_ERR) printf("signal(SIGALRM) error\n");
alarm(10);
if((n=read(STDIN_FILENO,line,10))<0) printf("read error\n");
alarm(0);
write(STDOUT_FILENO,line,n);
exit(0);
}
static void sig_alrm(int signo)
{
return;
}
#include
#include
#include
#include
#include
#include
#include
static void sig_alrm(int);
static jmp_buf env_alrm;
int main()
{
int n;
char line[100];
if(signal(SIGALRM,sig_alrm)==SIG_ERR) printf("signal(SIGARM) error\n");
if(setjmp(env_alrm)!=0) printf("read timeout");
alarm(10);
if((n=read(STDIN_FILENO,line,100))<0) printf("read error\n");
alarm(0);
write(STDOUT_FILENO,line,n);
exit(0);
}
static void sig_alrm(int signo)
{
longjmp(env_alrm,1);
}
'''
some error
include
include
include
include
include
include
include
include
define SIGBAD(signo) ((signo)<=0||(signo)>=NSIG)
int sigaddset(sigset_t *set,int signo)
{
if(SIGBAD(signo)){ errno=EINVAL; return (-1);}
*set|=1<<(signo-1);
return 0;
}
int sigdelset(sigset_t *set,int signo)
{
if(SIGBAD(signo)) { errno=EINVAL; return (-1);}
*set&=~(1<<(signo-1));
return 0;
}
int sigismember(const sigset_t set,int signo)
{
if(SIGBAD(signo)){ errno=EINVAL; return(-1);}
return ((set&(1<<(signo-1)))!=0);
}
void pr_mask(const char *str)
{
sigset_t sigset;
int errno_save;
errno_save=errno;
printf("%s",str);
if(sigismember(&sigset,SIGINT)) printf("SIGINT");
if(sigismember(&sigset,SIGQUIT)) printf("SIGQUIT");
if(sigismember(&sigset,SIGUSR1)) printf("SIGUSR1");
if(sigismember(&sigset,SIGALRM)) printf("SIGALRM");
printf("\n");
errno=errno_save;
}
static void sig_quit(int);
int main()
{
sigset_t newmask,oldmask,pendmask;
if(signal(SIGQUIT,sig_quit)==SIG_ERR) printf("can't catch SIGQUIT");
sigemptyset(&newmask);
sigaddset(&newmask,SIGQUIT);
if(sigprocmask(SIG_BLOCK,&newmask,&oldmask)<0) printf("SIG_BLOCK error");
sleep(5);
if(sigpending(&pendmask)<0) printf("sigpending error");
if(sigismember(&pendmask,SIGQUIT)) printf("\nSIGQUIT pending\n");
if(sigprocmask(SIG_SETMASK,&oldmask,NULL)<0) printf("SIG_SETMASK error");
printf("SIGQUIT unblocked\n");
sleep(5);
exit(0);
}
static void sig_quit(int signo)
{
printf("caught SIGQUIT\n");
if(signal(SIGQUIT,SIG_DFL)==SIG_ERR) printf("can't reset SIGQUIT");
return;
}
include
include
include
include
Sigfunc* signal(int signo,Sigfunc *func)
{
struct sigaction act,oact;
act.sa_handler=func;
sigemptyset(&act.sa_mask);
act.sa_flags=0;
if(signo==SIGALRM){
ifdef SA_INTERRUPT
act.sa_flags|=SA_INTERRUPT;
endif
}
else{
ifdef SA_RESTART
act.sa_flags|=SA_RESTART;
endif
}
if(sigaction(signo,&act,&oact)<0) return (SIG_ERR);
return (oact.sa_handler);
}
Sigfunc* signal_intr(int signo,Sigfunc *func)
{
struct sigaction act,oact;
act.sa_handler=func;
sigemptyset(&act.sa_mask);
ifdef SA_INTERRUPT
act.sa_flags|=SA_INTERRUPT;
endif
if(sigaction(signo,&act,&oact)<0) return (SIG_ERR);
return (oact.sa_handler);
}
'''先告一段落