Date: Sun, 22 Jul 2001 17:16:11 -0700 From: Bakul Shah <bakul@bitblocks.com> To: tlambert2@mindspring.com Cc: Joshua Goodall <joshua@roughtrade.net>, Bruce Evans <bde@zeta.org.au>, freebsd-fs@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG Subject: Re: flags on symlinks Message-ID: <200107230016.UAA17001@renown.cnchost.com> In-Reply-To: Your message of "Sun, 22 Jul 2001 15:11:10 PDT." <3B5B4F7E.8C48801E@mindspring.com>
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> > I guess there is general agreement that it is desirable to be able to set
> > schg,sunlink etc on symlinks and fifos.
> Probably devices, too, which is a can of worms, particularly
> with devfs.
> Already, the fchown/fchmod on sockets and other things which
> use a non VFS struct fileops fails -- I think this includes
> FIFO's.
> > The consistency argument goes like this:
> >
> > Currently exposed as accessor methods to VOP_SETATTR are:
> > chmod(2), fchmod(2), lchmod(2)
> > chown(2), fchown(2), lchown(2)
> > chflags(2), fchflags(2)
>
> I know the argument for adding more and more system calls;
> I just don't agree with it. BSDI has already suggested
> limiting the total number of FreeBSD system calls to something
> like less than 32 more, total, without going to another block
> much higher up, and having to have FreeBSD allocate a large,
> sparse system call array, adding potentially a lot of overhead,
> depending on future directions with the ABI.
Well, I won't mind if {,l}ch{mod,own,flags} etc become library
routines. Something like:
int
chown(const char* path, uid_t owner, gid_t group) {
int fd, err;
fd = open(path, O_EXCL);
if (!fd)
return errno;
err = fchown(fd, owner, group);
close(fd);
return err;
}
But then you must be able to open() a symlink (O_NOFOLLOW
flag must not make the open fail).
My main argument is for consistent treatment and for `equal
rights': if an object has an inode it must have the same
rights as any other object also with an inode. devfs is a
different kind of beast just like msdosfs so rights of an
inode based object are not the same as rights of devfs or
msdos fs. Anyway, I argue for either adding a syscall or
deleting a few to make a consistent set!
Earlier you said:
> If the chflags call was defined to always affect its
> target (and not follow links), then the user space utility
> could do the stat/readlink itself, and find the correct
> target, if it wasn't told to not follow links.
I don't like running namei twice. Between the stat/readlink
and chflags(), things can change.
[Digressing a bit...]
Ideally I want only the f* version of syscalls, so that you
_have_ to `open' an object. Open gives you a handle, a
'capability' to operate on the object. In the past I have
argued for *always* passing in a capability even for open().
Then you can throw away even the chdir() call. But then
it won't be the unix we know and love and hate!
-- bakul
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