Re: [Qemu-block] [Qemu-devel] [PATCH v2 1/1] block: improve error handling in raw_open

[Halil Pasic]

On 07/26/2016 05:42 PM, Max Reitz wrote:
>> +++ b/block/raw-posix.c
>> > @@ -485,6 +485,7 @@ static int raw_open_common(BlockDriverState *bs, QDict 
>> > *options,
>> >      s->fd = -1;
>> >      fd = qemu_open(filename, s->open_flags, 0644);
>> >      if (fd < 0) {
>> > +        error_setg_errno(errp, errno, "Could not open file");
> We don't guarantee that error_setg_errno() does not modify errno. (In
> practice it should not, but we don't guarantee that.)
> 


Thank you very much for your review. I have double checked, and I
remembered correctly: error_setg_errno saves and restores the original
errno, so that is why I assumed it does not. 

> Therefore, the common pattern is to save the errno value before calling
> this function, i.e. to put the function call...
> 
>> >          ret = -errno;
> ...here.
> 
> With that fixed, the patch should be good.
> 
> Max
> 
 
But now that you have this pointed out, I understand, it is better to
have no function calls between failure and saving the errno. I will post
a v3 and keep this in mind for the future. Sorry for the extra work.

Frankly, I'm a bit uncomfortable with asking (do not want to be pushy),
but do you have an opinion on the 'error_report_err' issue (pointed
out in the cover letter part)?

Cheers,
Halil

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