问题描述
我需要在SIGINT处理程序中执行清理功能,但无法将本地数据传递给它.这里是一个例子:
I need to execute clean up functions in SIGINT handler, but I can't pass local data to it. Here an example:
int main(int argc, char *argv[]) {
struct database *db = db_cursor();
sockfd_t master_socket = init_server();
signal(SIGINT, sigint_handler);
while (1) {
// accepting connections
}
}
void sigint_handler(int s) {
destroy_db(db);
shutdown(master_socket, SHUT_RDWR);
close(master_socket);
exit(EXIT_SUCCESS);
}
如何实现这种行为?我试过使这个变量是全局的,但是我无法在编译时调用此函数(错误:initializer元素不是编译时常量).
How can I implement such behaviour? I've tried make this variables are global, butI can't invoke this functions at compile time (error: initializer element is not a compile-time constant).
推荐答案
只能保证非常有限数量的函数是异步信号安全的,因此可以从信号处理程序exit()
f.e中调用.不属于他们.
Only a very limited number of functions is guaranteed to be async-signal-safe and therefore may be called from within a signal handler, exit()
f.e. does not belong to them.
采用其他方法:
#include <signal.h>
volatile sig_atomic_t sigint_received = 0; /* volatile might be necessary depending on
the system/implementation in use.
(see "C11 draft standard n1570: 5.1.2.3")*/
void sigint_handler(int s)
{
sigint_received = 1;
}
int main(void)
{
signal(SIGINT, sigint_handler);
while (!sigint_received)
{
/* Do stuff. */
}
/* Clean up here. */
}
有关更多信息,请参见
- 此处的Linux手册页
man 7 signal
- 此处的POSIX规范.
注意:要最大程度地便携,您想使用sigaction()
而不是signal()
.
Note: To be maximal portable you want to use sigaction()
instead of signal()
.
替换signal()
的代码可能如下所示:
The code to replace signal()
might look like this:
struct sigaction sa =
{
sigint_handler
/*, SA_RESTART */ /* Set this by if blocking calls like read() or accept()
should _not_ return on signal reception. */
};
if (-1 == sigaction(SIGINT, &sa, NULL))
{
perror("sigaction() failed");
exit(EXIT_FAILURE);
}
sigaction()
上的文档:
- Linux
- POSIX
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