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

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

On Mon, Jul 8, 2024 at 4:15 PM Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 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: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>

Thanks