Re: QEMU policy for real file tests

[Christian Schoenebeck]

On Donnerstag, 17. September 2020 11:55:00 CEST Thomas Huth wrote:
> 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

These answers already cover everything I need right now. Thanks!

Final question: if at some later point one large file needs to be created for 
some test case, is there some approximate size limit to stay below for not 
causing issues with free CI cloud services?

Best regards,
Christian Schoenebeck