Re: QEMU policy for real file tests

[Thomas Huth]

On 17/09/2020 11.37, Daniel P. Berrangé wrote:
> On Thu, Sep 17, 2020 at 10:26:36AM +0100, Alex Bennée wrote:
>>
>> Christian Schoenebeck <qemu_oss@crudebyte.com> writes:
>>
>>> Hi,
>>>
>>> is there a QEMU policy for test cases that create/write/read/delete real 
>>> files 
>>> and directories? E.g. should they be situated at a certain location and is 
>>> any 
>>> measure of sandboxing required?
>>
>> I don't think we have a hard and fast policy. It also depends on what
>> you are doing the test in - but ideally you should use a secure mktempd
>> (that can't clash) and clean-up after you are finished. This is a bit
>> easier in python than shell I think.
> 
> mktempd will end up on /tmp usually which can be tmpfs and size limited,
> so be mindful of the size of files you create. Don't assume you can
> create multi-GB sized files !  Creating a temp dir underneath the build
> dir (effectively CWD of the test) is a reasonable alternative.

Another thing to consider: If you want to create Unix sockets in your
tests, make sure that the file name does not get too long, since there
are limits on certain systems - i.e. socket files should be created in a
/tmp subdirectory, indeed.

 Thomas