我的孩子过程无法开始工作。我需要传递信号并执行readUsual
功能。
这是一小段代码:
int main()
{
pid_t pid2 = fork();
if (pid2 < 0)
printf("Can't create child process\n");
else if (pid2==0)
{
//this block never execute
printf("Process2, pid=%d\n",getpid());
signal(SIGUSR1,readUsual);
}
else
{
kill(pid2,SIGUSR1);
printf("%s\n","Proccess1 end");
for(;;);
}
return 0;
}
答案 0 :(得分:4)
您需要以某种方式添加同步,或者在signal()
之前致电fork()
。
使用当前代码,您无法确定子进程在收到信号之前调用signal()
。在处理指令之前接收信号将停止子进程。
示例:
#include <stdio.h>
#include <sys/types.h>
#include <signal.h>
#include <unistd.h>
static int received = 0;
void readUsual(int sig)
{
if (sig == SIGUSR1)
{
received = 1;
}
}
int main()
{
signal(SIGUSR1,readUsual);
pid_t pid2 = fork();
if (pid2 < 0)
printf("Can't create child process\n");
else if (pid2==0)
{
printf("Process2, pid=%d\n",getpid());
while (!received)
;
printf("SIGUSR1 received.\n");
}
else
{
kill(pid2,SIGUSR1);
printf("%s\n","Proccess1 end");
while (1)
;
}
return 0;
}
使用此代码输出的示例:
Process1 end
Process2, pid=1397
SIGUSR1 received