svn commit: r365643 - head/bin/cp

[Warner Losh]

On Thu, Sep 24, 2020 at 12:41 AM Stefan Esser <se at freebsd.org> wrote:

> Am 23.09.20 um 19:23 schrieb Warner Losh> But for this issue, we're not
> mounting devfs early enough.  We should
> > fix that. Removing /dev/null from the boot process likely is never going
> > to happen because we use it all over the place to discard output...
> > There's ~200 instances of it in the boot rc scripts, so getting rid of
> > it there would also be quite the effort, with the same question.
>
> Removal of /dev/null from rc.d scripts should be quite simple,
> since most cases could just use ">-" (close file descriptor)
> instead. Other usage could be substituted with ":>" followed
> by chown.
>

So closing fd1 and fd2 doesn't cause them to be available for these
programs to get as an fd on open, causing other issues?

But >- isn't documented in sh(1) as doing the close thing. On a whim I did
the following:
$ echo fred >-
$ ls -last ./-
4 -rw-r--r--  1 imp  imp  5 Sep 24 00:50 ./-
$ cat ./-
fred
$
which suggests maybe you now have a lot of files named - instead...


> I'd be willing to generate patches for review, if there is any
> chance such a change might be accepted into -CURRENT.
>
> I could not find any use of /dev/zero,


Yea, I'd thought we used it in libc, but I can't find any evidence of that
with grep now that I've gone looking for it. For get that specific one :)


> but e.g. rc.d/syscons
> uses ${kbddev} (i.e. /dev/ttyv0) and rc.d/zvol performs swapon
> on /dev/zvol/${name}, rc.d/random uses /dev/random and so on.
>

So those interactions should be disaled by rc variables...  Or we should be
failing the operation...


> But those further references to /dev nodes will in general be
> NOPs if /dev is not available (some test for existence of the
> node they rely on, other just fail trying to access them, but
> without negative effect on going multi-user).
>

Yea, that's more minor, but if /dev/ isn't there, they likely should fail,
or shouldn't proceed... But in a way that allows the rest of the rc scripts
to continue...

Warner