[CRIU] [PATCH] service: rotate log by SIGHUP

[Vladimir Davydov]

On 02/11/2014 11:11 AM, Ruslan Kuprieiev wrote:
> Because we wan't service to work non-stop.
> And, as far as I know, by just using logrotate we will need to restart
> service.

Not necessarily, you can specify what should be done after rotate
(`postrotate'), e.g. send a signal to your service so that it could
reopen the logfile. However, I guess that `copytruncate' would be enough
in your case.

>
> On 11.02.2014 10:59, Vladimir Davydov wrote:
>> Sorry for butting in, but why don't you use logrotate(8)?
>>
>> On 02/11/2014 10:41 AM, Ruslan Kuprieiev wrote:
>>> Many existing daemons rotate logs by SIGHUP, so lets do the same
>>> with our service.
>>>
>>> Signed-off-by: Ruslan Kuprieiev <kupruser at gmail.com>
>>> ---
>>>   cr-service.c | 30 ++++++++++++++++++++++++++----
>>>   1 file changed, 26 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/cr-service.c b/cr-service.c
>>> index 26dd3e2..49454e7 100644
>>> --- a/cr-service.c
>>> +++ b/cr-service.c
>>> @@ -489,12 +489,21 @@ static void reap_worker(int signo)
>>>       }
>>>   }
>>>   -static int setup_sigchld_handler()
>>> +static void rotate_log(int signo)
>>> +{
>>> +    pr_info("Rotating log.\n");
>>> +
>>> +    if (log_rotate())
>>> +        exit(1);
>>> +}
>>> +
>>> +static int setup_signal_handlers()
>>>   {
>>>       struct sigaction action;
>>>         sigemptyset(&action.sa_mask);
>>>       sigaddset(&action.sa_mask, SIGCHLD);
>>> +    sigaddset(&action.sa_mask, SIGHUP);
>>>       action.sa_handler    = reap_worker;
>>>       action.sa_flags        = SA_RESTART;
>>>   @@ -503,15 +512,23 @@ static int setup_sigchld_handler()
>>>           return -1;
>>>       }
>>>   +    action.sa_handler    = rotate_log;
>>> +
>>> +    if (sigaction(SIGHUP, &action, NULL)) {
>>> +        pr_perror("Can't setup SIGUSR1 handler");
>>> +        return -1;
>>> +    }
>>> +
>>>       return 0;
>>>   }
>>>   -static int restore_sigchld_handler()
>>> +static int restore_signal_handlers()
>>>   {
>>>       struct sigaction action;
>>>         sigemptyset(&action.sa_mask);
>>>       sigaddset(&action.sa_mask, SIGCHLD);
>>> +    sigaddset(&action.sa_mask, SIGHUP);
>>>       action.sa_handler    = SIG_DFL;
>>>       action.sa_flags        = SA_RESTART;
>>>   @@ -520,6 +537,11 @@ static int restore_sigchld_handler()
>>>           return -1;
>>>       }
>>>   +    if (sigaction(SIGHUP, &action, NULL)) {
>>> +        pr_perror("Can't restore SIGHUP handler");
>>> +        return -1;
>>> +    }
>>> +
>>>       return 0;
>>>   }
>>>   @@ -596,7 +618,7 @@ int cr_service(bool daemon_mode)
>>>           }
>>>       }
>>>   -    if (setup_sigchld_handler())
>>> +    if (setup_signal_handlers())
>>>           goto err;
>>>         while (1) {
>>> @@ -615,7 +637,7 @@ int cr_service(bool daemon_mode)
>>>           if (child_pid == 0) {
>>>               int ret;
>>>   -            if (restore_sigchld_handler())
>>> +            if (restore_signal_handlers())
>>>                   exit(1);
>>>                 close(server_fd);
>