cgo如何处理信号？

Question

我遇到了Go程序使用.so lib的问题,而c代码需要处理SIGALRM信号.但似乎一旦信号SIGALRM发布,程序就会崩溃.从"The Go Programming Language"我看到:

如果非Go代码安装任何信号处理程序,则必须使用带有sigaction的SA_ONSTACK标志.如果未收到信号,则可能导致程序崩溃.

任何人都可以通过sigaction显示SA_ONSTACK标志的用法.我非常感激.

以下是我的代码:

// LIC_TIMER_CALLBACK_FUNC is a function pointer

static LIC_TIMER_CALLBACK_FUNC s_pfnTmCallBack;

static void _OS_TriggerTask(int iSig)
{
    logInfo("_OS_TriggerTask start...");
    if (LIC_NULL_PTR != s_pfnTmCallBack)
    {
        logInfo("call timer callback...");
        s_pfnTmCallBack(0);    
    }
    logInfo("_OS_TriggerTask end...");
}

// set the trigger
int OS_StartTrigger(int ulLength, LIC_TIMER_CALLBACK_FUNC pfnTmCallBack)
{    
    logInfo("OS_StartTrigger start...");

s_pfnTmCallBack = pfnTmCallBack;

struct sigaction stSigact; 

stSigact.sa_handler = _OS_TriggerTask;
stSigact.sa_flags   = SA_ONSTACK;
sigemptyset(&stSigact.sa_mask);
int iRet = sigaction(SIGALRM, &stSigact, NULL);

if(0 != iRet)
{
    logError("set signal failed...");
}
else
{
    logInfo("set signal success...");
}

/* set time interval */
struct itimerval stItimerVal;
stItimerVal.it_value.tv_sec = 60;
stItimerVal.it_value.tv_usec = 0;
stItimerVal.it_interval = stItimerVal.it_value;

iRet = setitimer(ITIMER_REAL, &stItimerVal, NULL);

if(0 != iRet)
{
    logError("set timer failed...");
    return -1;
}

logInfo("OS_StartTrigger end...");
return 0;
}

Answer 1

看起来 Go 存储库中有一个测试可以满足您的需求。测试的工作原理如下：main.c旨在测试所有发行版的 cgo 中的信号处理。查看 unix 发行版 ( main_unix.c ) 的处理程序，您会得到：

int install_handler() {
    // Install our own signal handler.
    memset(&sa, 0, sizeof sa);
    sa.sa_sigaction = handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
    memset(&osa, 0, sizeof osa);
    sigemptyset(&osa.sa_mask);
    if (sigaction(SIGSEGV, &sa, &osa) < 0) {
        perror("sigaction");
        return 2;
    }
    if (osa.sa_handler == SIG_DFL) {
        fprintf(stderr, "Go runtime did not install signal handler\n");
        return 2;
    }
    // gccgo does not set SA_ONSTACK for SIGSEGV.
    if (getenv("GCCGO") == NULL && (osa.sa_flags&SA_ONSTACK) == 0) {
        fprintf(stderr, "Go runtime did not install signal handler\n");
        return 2;
    }
    oldHandler = osa.sa_sigaction;

    return 0;
}

现在测试正在向 中添加处理程序SIGSEGV，因此请将其替换为有问题的信号。