genfs_can_chtimes() (more duplicate code)

[Elad Efrat <elad%NetBSD.org@localhost>]

Hi,

We have similar code to check if we can change the timestamps on files
in the following file-systems: ptyfs, smbfs, tmpfs, udf, ext2, ufs,
msdosfs. The code looks like this:

   1113 if (!issuperuser) {
   1114         if (euid != uid)
   1115                 return EPERM;
   1116         if ((setattrflags & VA_UTIMES_NULL) == 0) {
   1117                 error = VOP_ACCESS(vp, VWRITE, cred);
   1118                 if (error)
   1119                         return error;
   1120         }
   1121 }

...only much uglier, in file-systems that are not udf. :)

I would like to introduce the following, in genfs_vnops.c:

        int
        genfs_can_chtimes(vnode_t *vp, u_int vaflags, uid_t owner_uid,
            kauth_cred_t cred)
        {
                int error;

                /* Must be root, or... */
                error = kauth_authorize_generic(cred,
                    KAUTH_GENERIC_ISSUSER, NULL);
                if (!error)
                        return (0);

                /* must be owner, and... */
                if (kauth_cred_geteuid(cred) != owner_uid)
                        return (EPERM);

                /* have write access if changing times. */
                if ((vaflags & VA_UTIMES_NULL) == 0) {
                        error = VOP_ACCESS(vp, VWRITE, cred);
                        if (error)
                                return (error);
                }

                return (0);
        }

To be used as a replacement. Usage:

        error = genfs_can_chtimes(vp, va_flags, uid, cred);
        if (error)
                return (error);

Are there any objections to such a change?

Thanks,

-e.