发送信号为什么出现User defined signal 1

[liyi54188]

我发信号的时候怎么会出现：User defined signal 1，请大家指教下，谢谢了

#include <stdio.h>

#include <stdlib.h>

#include <signal.h>

#include <unistd.h>


void sigusr1_handler(int signo)

{

printf("catch SIGUSR1\n");


sleep(15);


printf("back to main\n");

}


int main(void)

{

struct sigaction act;


act.sa_handler = sigusr1_handler;

act.sa_flags = SA_NODEFER;

act.sa_sigaction = NULL;

sigemptyset(&act.sa_mask);


if(sigaction(SIGUSR1, &act, NULL) == -1)

{

perror("fail to set handler for SIGUSR1");

exit(1);

}


printf("process begin\n");
sleep(15);


printf("done\n");


return 0;


}

[liyi54188]

多谢指教了，是这个的问题，注释掉就好了，为什么act.sa_sigaction = NULL;要被注释掉阿，他不是个替代处理函数，只有当Sa_flags的值为SA_SIGINFO才使用act.sa_sigaction，我以前好像也是这么写没发现问题，你能否指教下我阿，谢谢了！！

[name_110]

act.sa_sigaction = NULL;这一行去掉就没问题了！

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>

void sigusr1_handler(int signo)
{
printf("catch SIGUSR1\n");
sleep(15);
printf("back to main\n");
}

int main(void)
{
struct sigaction act;
act.sa_handler = sigusr1_handler;
act.sa_flags = SA_NODEFER;
sigemptyset(&act.sa_mask);
if(sigaction(SIGUSR1, &act, NULL) == -1)
{
perror("fail to set handler for SIGUSR1");
exit(1);
}
printf("process begin\n");
sleep(15);
printf("done\n");
return 0;
}

[Mo971443315]

这为仁兄肯定是上课时没注意了，act.sa_handler 和act.sa_sigaction 只能选择用一个，man sigaction 里有这么一句话，On some architectures a union is involved: do not assign to both sa_handler and sa_sigaction.说了这个应该知道原因了吧

[liyi54188]

呵呵，多谢指教了！

[z540763534]

看回复解决问题