[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 11/13] 9p: darwin: Mark mknod as unsupported

From: Keno Fischer
Subject: Re: [Qemu-devel] [PATCH 11/13] 9p: darwin: Mark mknod as unsupported
Date: Thu, 31 May 2018 19:21:08 -0400

On Thu, May 31, 2018 at 7:06 PM, Keno Fischer <address@hidden> wrote:
> On Thu, May 31, 2018 at 6:56 PM, Keno Fischer <address@hidden> wrote:
>>>> My concern was that allowing this would cause unexpected
>>>> behavior, since the device numbers will differ between OS X
>>>> and Linux. Though maybe this isn't the place to worry about
>>>> that.
>>> The numbers may differ indeed but we don't really care since the
>>> server never opens device files. This is just a directory entry.
>> Ok, let me try to implement it. However, I don't think it is possible
>> to implement mknodat (or at least I can't think of how) on Darwin
>> directly. I could use regular mknod, but presumably, this is used
>> to avoid a race condition between creating the device and setting
>> the permissions. Can you think of a good way to resolve that?
> Would it work to fchdir in to the directory and use a cwd-relative
> mknod, then fchdir back? Or do we need to maintain the cwd
> while in this code?

Sorry for the triple-self-post here, but I took a look at the Darwin kernel
source and there's an unexposed (from the Darwin C library) syscall that
only changes the current thread's cwd. That seems like it should be safe,
so I'll go ahead and use that to implement mknodat. I'll also submit a
feature request to apple to implement mknodat.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]