Question

我已经在c ++中为linux创建了一个守护进程，但是，子进程似乎没有做任何事情。一旦它到达if（pid＆gt; 0）语句，一切似乎都停止了。 Daemon.Start（）的代码如下：

//Process ID and Session ID
pid_t pid,sid;

//Fork off the Parent Process
pid = fork();
if(pid < 0)
    exit(EXIT_FAILURE);
//If PID is good, then exit the Parent Process
if(pid > 0)
    exit(EXIT_SUCCESS);

//Change the file mode mask
umask(0);

//Create a new SID for the Child Process
sid = setsid();
if(sid < 0)
{
    exit(EXIT_FAILURE);
}

//Change the current working directory
if((chdir("/")) < 0)
{
    //Log the failure
    exit(EXIT_FAILURE);
}

//Close out the standard file descriptors
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);

//The main loop.
Globals::LogError("Service started.");
while(true)
{
    //The Service task
    Globals::LogError("Service working.");
    if(!SystemConfiguration::IsFirstRun() && !SystemConfiguration::GetMediaUpdateReady())
    {
        SyncServer();
    }
    sleep(SystemConfiguration::GetServerConnectionFrequency()); //Wait 30 seconds

}

exit(EXIT_SUCCESS);

任何帮助都会很棒！：）

Answer 1

我非常确定您的子进程在sid < 0或chdir("/") < 0 if语句中死亡。在退出之前写入stderr以解决问题所在：

//Create a new SID for the Child Process
sid = setsid();
if(sid < 0)
{
    fprintf(stderr,"Failed to create SID: %s\n",strerror(errno));
    exit(EXIT_FAILURE);
}

//Change the current working directory
int chdir_rv = chdir("/");
if(chdir_rv < 0)
{
    fprintf(stderr,"Failed to chdir: %s\n",strerror(errno));
    exit(EXIT_FAILURE);
}

您需要包含<errno.h>和<string.h>才能分别定义errno和strerror。

此致

Linux守护进程无法正常工作

1 个答案: