Re: [PATCH 07/15] build: syscalls: Add pivot-root.

[Ludovic Courtès]

"Thompson, David" <address@hidden> skribis:

> On Tue, Jul 7, 2015 at 9:35 AM, Ludovic Courtès <address@hidden> wrote:
>> David Thompson <address@hidden> skribis:
>>
>>> From: David Thompson <address@hidden>
>>>
>>> * guix/build/syscalls.scm (pivot-root): New procedure.
>>> * tests/syscalls.scm: Test it.
>>
>> [...]
>>
>>> +(test-assert "pivot-root"
>>> +  (match (pipe)
>>> +    ((in . out)
>>> +     (match (clone (logior CLONE_NEWUSER CLONE_NEWNS))
>>> +       (0
>>> +        (close in)
>>> +        (call-with-temporary-directory
>>> +         (lambda (root)
>>> +           (let ((put-old (string-append root "/real-root")))
>>> +             (mount "none" root "tmpfs")
>>> +             (mkdir put-old)
>>> +             (call-with-output-file (string-append root "/test")
>>> +               (lambda (port)
>>> +                 (display "testing\n" port)))
>>> +             (pivot-root root put-old)
>>> +             ;; The test file should now be located inside the root 
>>> directory.
>>> +             (write (file-exists "/test") out)
>>> +             (close out))))
>>> +        (primitive-exit 0))
>>> +       (pid
>>> +        (close out)
>>> +        (read in))))))
>>
>> Shouldn’t it be:
>>
>>   (file-exists? (string-append put-old "/test"))
>
> No, because put-old contains the current system root directory.  I
> wanted to test that the file I made in the temporary directory is now
> located in the new root file system.  I hope this makes sense.

Oh, right.  (The other part was the missing question mark, as you
noticed.)

Ludo’.