Date: Wed, 2 Jul 2025 16:54:18 -0600 From: Alan Somers <asomers@freebsd.org> To: Rick Macklem <rick.macklem@gmail.com> Cc: FreeBSD CURRENT <freebsd-current@freebsd.org> Subject: Re: RFC: checking file systems support UF_HIDDEN, UF_SYSTEM Message-ID: <CAOtMX2jVdbtGb=%2BCEAbaWF2oiSTD=V=js2HOjQHnpJpCB1i2zw@mail.gmail.com> In-Reply-To: <CAM5tNy5eoY5f-fo9BKc4v34XKXF6%2B6Ae7Zpq=FH7owaSRYSHmw@mail.gmail.com>
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[-- Attachment #1 --] On Wed, Jul 2, 2025, 3:03 PM Rick Macklem <rick.macklem@gmail.com> wrote: > Hi, > > I am implementing the "hidden" and "system" attributes for > NFSv4 using UF_HIDDEN and UF_SYSTEM. > > In a couple of places in the code, I need to know if a file > system supports these flags. > I can think of two ways to do this. > #1 - Create a new VFCF_HIDSYS flag that is set via VFS_SET() > for file systems that support the UF_HIDDEN and UF_SYSTEM > flags and test for that flag being set. > or > #2 - Write it this way... > if (strcmp(vp->v_mount->mnt_vfc->vfc_name, "zfs") != 0 || > strcmp(vp->v_mount->mnt_vfc->vfc_name, "ufs") != 0 || > strcmp(vp->v_mount->mnt_vfc->vfc_name, "msdosfs") != 0 || > strcmp(vp->v_mount->mnt_vfc->vfc_name, "tmpfs") != 0) > > Which do you think is preferable (or do you have another idea)? > > Thanks for any comments, rick > The strcmp method isn't very good, because it doesn't account for the possibility that some filesystems may only support the flags conditionally, depending on formatting options. I vote for method 1. > [-- Attachment #2 --] <div dir="auto"><div><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Wed, Jul 2, 2025, 3:03 PM Rick Macklem <<a href="mailto:rick.macklem@gmail.com">rick.macklem@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi,<br> <br> I am implementing the "hidden" and "system" attributes for<br> NFSv4 using UF_HIDDEN and UF_SYSTEM.<br> <br> In a couple of places in the code, I need to know if a file<br> system supports these flags.<br> I can think of two ways to do this.<br> #1 - Create a new VFCF_HIDSYS flag that is set via VFS_SET()<br> for file systems that support the UF_HIDDEN and UF_SYSTEM<br> flags and test for that flag being set.<br> or<br> #2 - Write it this way...<br> if (strcmp(vp->v_mount->mnt_vfc->vfc_name, "zfs") != 0 ||<br> strcmp(vp->v_mount->mnt_vfc->vfc_name, "ufs") != 0 ||<br> strcmp(vp->v_mount->mnt_vfc->vfc_name, "msdosfs") != 0 ||<br> strcmp(vp->v_mount->mnt_vfc->vfc_name, "tmpfs") != 0)<br> <br> Which do you think is preferable (or do you have another idea)?<br> <br> Thanks for any comments, rick<br></blockquote></div></div><div dir="auto"><br></div><div dir="auto">The strcmp method isn't very good, because it doesn't account for the possibility that some filesystems may only support the flags conditionally, depending on formatting options. I vote for method 1.</div><div dir="auto"><div class="gmail_quote gmail_quote_container"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> </blockquote></div></div></div>home | help
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