Re: [PATCH for-4.19] tools/libxs: Fix fcntl() invocation in set_cloexec()

[Jürgen Groß <jgross@xxxxxxxx>]

On 08.07.24 17:15, Andrew Cooper wrote:
> set_cloexec() had a bit too much copy&pate from setnonblock(), and
> insufficient testing on ancient versions of Linux...
>
> As written (emulating ancient linux by undef'ing O_CLOEXEC), strace shows:
>
>    open("/dev/xen/xenbus", O_RDWR)         = 3
>    fcntl(3, F_GETFL)                       = 0x8002 (flags O_RDWR|O_LARGEFILE)
>    fcntl(3, 0x8003 /* F_??? */, 0x7ffe4a771d90) = -1 EINVAL (Invalid argument)
>    close(3)                                = 0
>
> which is obviously nonsense.
>
> Switch F_GETFL -> F_GETFD, and fix the second invocation to use F_SETFD.  With
> this, strace is rather happer:
>
>    open("/dev/xen/xenbus", O_RDWR)         = 3
>    fcntl(3, F_GETFD)                       = 0
>    fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
>
> Fixes: bf7c1464706a ("tools/libxs: Fix CLOEXEC handling in get_dev()")
> Reported-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen