[CRIU] [PATCH] util: disable log service in cr_system_userns if error fd was -1

[Stanislav Kinsburskiy]

22.04.2016 17:58, Pavel Emelyanov пишет:
> On 04/22/2016 06:23 PM, Stanislav Kinsburskiy wrote:
>> In case of error fd was negative, log_fd is _moved_ as STDERR for the child.
>> After move, log_fd is closed, and thus log service is broken and any error
>> prints will disappear.
>> This patch disables log service, thus redirecting error output to STDERR
>> (which is log fd in this case).
>>
>> Calling of log fini is:
>> 1) to early: reopen_fd_as_nocheck will fail
>> 2) to much: close_safe will print error message, because log fd was already
>> closed
>>
>> Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
>> ---
>>   criu/util.c |    6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/criu/util.c b/criu/util.c
>> index dae6031..12ce8b4 100644
>> --- a/criu/util.c
>> +++ b/criu/util.c
>> @@ -641,9 +641,6 @@ int cr_system_userns(int in, int out, int err, char *cmd,
>>   		    move_img_fd(&err, STDIN_FILENO))
>>   			goto out_chld;
>>   
>> -		if (stop_log_fd)
>> -			log_fini();
>> -
>>   		if (in < 0) {
>>   			close(STDIN_FILENO);
>>   		} else {
>> @@ -660,6 +657,9 @@ int cr_system_userns(int in, int out, int err, char *cmd,
>>   		if (reopen_fd_as_nocheck(STDERR_FILENO, err))
>>   			goto out_chld;
>>   
>> +		if (stop_log_fd)
>> +			clear_bit(LOG_FD_OFF, sfd_map);
> Messing directly with sfd_map here is bad idea. Add call __log_fini()
> that finis the log with dead file descriptor.

The problem here is not in log_fini(), but in close_service_fd(). Even 
in close_safe(), to be precise.
What if I add check for valid fd to close_safe()?

>> +
>>   		execvp(cmd, argv);
>>   
>>   		pr_perror("exec failed");
>>
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>> .
>>