Re: [Qemu-devel] Re: [PATCH 1/2] qemu-io: retry fgets() when errno is EINTR

[Kevin Wolf <kwolf@redhat.com>]

Am 16.06.2010 18:52, schrieb MORITA Kazutaka:
> At Wed, 16 Jun 2010 13:04:47 +0200,
> Kevin Wolf wrote:
>>
>> Am 15.06.2010 19:53, schrieb MORITA Kazutaka:
>>> posix-aio-compat sends a signal in aio operations, so we should
>>> consider that fgets() could be interrupted here.
>>>
>>> Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
>>> ---
>>>  cmd.c |    3 +++
>>>  1 files changed, 3 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/cmd.c b/cmd.c
>>> index 2336334..460df92 100644
>>> --- a/cmd.c
>>> +++ b/cmd.c
>>> @@ -272,7 +272,10 @@ fetchline(void)
>>>  		return NULL;
>>>  	printf("%s", get_prompt());
>>>  	fflush(stdout);
>>> +again:
>>>  	if (!fgets(line, MAXREADLINESZ, stdin)) {
>>> +		if (errno == EINTR)
>>> +			goto again;
>>>  		free(line);
>>>  		return NULL;
>>>  	}
>>
>> This looks like a loop replaced by goto (and braces are missing). What
>> about this instead?
>>
>> do {
>>     ret = fgets(...)
>> } while (ret == NULL && errno == EINTR)
>>
>> if (ret == NULL) {
>>    fail
>> }
>>
> 
> I agree.
> 
> However, it seems that my second patch have already solved the
> problem.  We register this readline routines as an aio handler now, so
> fgets() does not block and cannot return with EINTR.
> 
> This patch looks no longer needed, sorry.

Good point. Thanks for having a look.

Kevin