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

[Ruslan Kuprieiev]

On 11.02.2014 11:28, Vladimir Davydov wrote:
> 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.

But what if service will write something between the moment when 
logrotate will copy log and the moment when it will send signal to service?

>> 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);