svn commit: r365643 - head/bin/cp
Warner Losh
imp at bsdimp.com
Tue Sep 22 22:02:11 UTC 2020
On Tue, Sep 22, 2020 at 3:55 PM Kyle Evans <kevans at freebsd.org> wrote:
> On Tue, Sep 22, 2020 at 4:53 PM Ian Lepore <ian at freebsd.org> wrote:
> >
> > On Tue, 2020-09-22 at 15:50 -0600, Warner Losh wrote:
> > > I think it's a great leap sideways, but I've done cp /dev/null foo to
> > > clear
> > > it out for 35 years now... It's why it feels like a workaround.
> > >
> > > Though it is a legit optimization, no matter the feelings. As for
> > > clearer,
> > > I'm less sure since then I have to remember what the : operator does.
> > >
> > > Warner
> > >
> >
> > For me, :> is idiomatic (but ugly).
> >
> > On the other hand, the cp /dev/null had a nice dogfooding aspect to
> > it... when we broke cp by accident, its use in the build system was the
> > first alarm to go off.
> >
> > --Ian
> >
>
> To be honest, this is a case that really should be covered by
> regression tests somewhere.
>
It should (but isn't yet).
Ian is right for old-school FreeBSD thinking. In that thinking the build
system should use an eclectic mix of tools to act as a fire-wall against
accidental breakage.
Complete, effective, test suites give much better coverage... if they are
run...
So until we run tests frequently, with loud regression squawking that's as
effective as build breakage, I tend to fall in the 'all of the above' camp
until that's in place... :)
Warner
P.S. though not, if I suppose, if it means that we're slowing down the
regression coverage uptake...
> > On Tue, Sep 22, 2020 at 3:48 PM Alan Somers <asomers at freebsd.org>
> > > wrote:
> > >
> > > > It doesn't feel like a workaround to me. I think Kyle's version is
> > > > clearer than the original.
> > > >
> > > > On Tue, Sep 22, 2020 at 3:45 PM Warner Losh <imp at bsdimp.com> wrote:
> > > >
> > > > >
> > > > >
> > > > > On Tue, Sep 22, 2020 at 3:42 PM Kyle Evans <kevans at freebsd.org>
> > > > > wrote:
> > > > >
> > > > > > cp is already fixed, people are still feeling the fallout of
> > > > > > being
> > > > > > within those revisions and needing to bootstrap their own cp.
> > > > > > We can
> > > > > > reduce the number of components these invocations rely on
> > > > > > trivially to
> > > > > > shell built-in mechanics, why not do so?
> > > > > >
> > > > >
> > > > > Fair point. I just bristle at putting workarounds in for valid
> > > > > /bin/sh
> > > > > syntax because we opposed for a few days. so long as it's an
> > > > > unconditional
> > > > > clearing of the file to be zero length, I'm OK with that.
> > > > >
> > > > > Warner
> > > > >
> > > > >
> > > > > > On Tue, Sep 22, 2020 at 4:40 PM Warner Losh <imp at bsdimp.com>
> > > > > > wrote:
> > > > > > >
> > > > > > > So why do we need a workaround at all? cp /dev/null has been
> > > > > > > fixed,
> > > > > >
> > > > > > and that's way more important to get right.
> > > > > > >
> > > > > > > I don't want to paper-over issues with this at all, though if
> > > > > > > we use
> > > > > >
> > > > > > the host's (now broken) cp, I suppose that might be OK in the
> > > > > > short term.
> > > > > > If that's the case, then maybe this is OK.
> > > > > > >
> > > > > > > Otherwise, I'd strongly prefer we fix cp.
> > > > > > >
> > > > > > > Warner
> > > > > > >
> > > > > > > On Tue, Sep 22, 2020 at 3:31 PM Alan Somers <
> > > > > > > asomers at freebsd.org>
> > > > > >
> > > > > > wrote:
> > > > > > > >
> > > > > > > > +1.
> > > > > > > >
> > > > > > > > On Tue, Sep 22, 2020 at 3:27 PM Kyle Evans <
> > > > > > > > kevans at freebsd.org>
> > > > > >
> > > > > > wrote:
> > > > > > > > >
> > > > > > > > > I'm running a build at the suggestion of mjg to confirm
> > > > > > > > > there aren't
> > > > > > > > > any others hiding that can be converted, and I will
> > > > > > > > > commit after I've
> > > > > > > > > verified that this is it.
> > > > > > > > >
> > > > > > > > > On Tue, Sep 22, 2020 at 4:02 PM Alan Somers <
> > > > > > > > > asomers at freebsd.org>
> > > > > >
> > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > LGTM.
> > > > > > > > > >
> > > > > > > > > > On Tue, Sep 22, 2020 at 2:59 PM Kyle Evans <
> > > > > > > > > > kevans at freebsd.org>
> > > > > >
> > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > Perhaps:
> > > > > > > > > > >
> > > > > > > > > > > diff --git a/stand/i386/zfsboot/Makefile
> > > > > >
> > > > > > b/stand/i386/zfsboot/Makefile
> > > > > > > > > > > index ff315abc0ef..7e362b43a39 100644
> > > > > > > > > > > --- a/stand/i386/zfsboot/Makefile
> > > > > > > > > > > +++ b/stand/i386/zfsboot/Makefile
> > > > > > > > > > > @@ -81,7 +81,7 @@ zfsboot.ld: zfsboot.ldr zfsboot.bin
> > > > > > > > > > > ${BTXKERN}
> > > > > > > > > > > -o ${.TARGET} -P 1 zfsboot.bin
> > > > > > > > > > >
> > > > > > > > > > > zfsboot.ldr:
> > > > > > > > > > > - cp /dev/null ${.TARGET}
> > > > > > > > > > > + :> ${.TARGET}
> > > > > > > > > > >
> > > > > > > > > > > zfsboot.bin: zfsboot.out
> > > > > > > > > > > ${OBJCOPY} -S -O binary zfsboot.out
> > > > > > > > > > > ${.TARGET}
> > > > > > > > > > > diff --git a/stand/libsa/Makefile
> > > > > > > > > > > b/stand/libsa/Makefile
> > > > > > > > > > > index effece9e01b..63cd46a9c54 100644
> > > > > > > > > > > --- a/stand/libsa/Makefile
> > > > > > > > > > > +++ b/stand/libsa/Makefile
> > > > > > > > > > > @@ -122,7 +122,7 @@ beforedepend:
> > > > > > > > > > > ln -sf ${SRCTOP}/include/arpa/inet.h
> > > > > > > > > > > arpa/inet.h; \
> > > > > > > > > > > ln -sf ${SRCTOP}/include/arpa/t
> > > > > > > > > > > ftp.h arpa/tftp.h; \
> > > > > > > > > > > for i in _time.h _strings.h _string.h; do \
> > > > > > > > > > > - [ -f xlocale/$$i ] || cp /dev/null
> > > > > > > > > > > xlocale/$$i; \
> > > > > > > > > > > + [ -f xlocale/$$i ] || :> xlocale/$$i;
> > > > > > > > > > > \
> > > > > > > > > > > done; \
> > > > > > > > > > > for i in ${STAND_H_INC}; do \
> > > > > > > > > > > ln -sf ${SASRC}/stand.h $$i; \
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > On Tue, Sep 22, 2020 at 3:58 PM Alan Somers <
> > > > > > > > > > > asomers at freebsd.org>
> > > > > >
> > > > > > wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > Looks like two places in stand. Is there any
> > > > > > > > > > > > reason why
> > > > > >
> > > > > > Mateusz's suggestion wouldn't work?
> > > > > > > > > > > >
> > > > > > > > > > > > > rg -g Makefile 'cp.*/dev/null'
> > > > > > > > > > > >
> > > > > > > > > > > > stand/libsa/Makefile
> > > > > > > > > > > > 125: [ -f xlocale/$$i ] || cp /dev/null
> > > > > > > > > > > > xlocale/$$i; \
> > > > > > > > > > > >
> > > > > > > > > > > > stand/i386/zfsboot/Makefile
> > > > > > > > > > > > 82: cp /dev/null ${.TARGET}
> > > > > > > > > > > >
> > > > > > > > > > > > On Tue, Sep 22, 2020 at 2:54 PM Mateusz Guzik <
> > > > > >
> > > > > > mjguzik at gmail.com> wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > Can we instead add a workaround to the build
> > > > > > > > > > > > > tree?
> > > > > > > > > > > > >
> > > > > > > > > > > > > Where is cp /dev/null coming from anyway? Perhaps
> > > > > > > > > > > > > this can be
> > > > > >
> > > > > > patched
> > > > > > > > > > > > > to touch the target file.
> > > > > > > > > > > > >
> > > > > > > > > > > > > On 9/22/20, Alan Somers <asomers at freebsd.org>
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > On Tue, Sep 22, 2020 at 2:48 PM Kyle Evans <
> > > > > >
> > > > > > kevans at freebsd.org> wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > On Fri, Sep 11, 2020 at 3:49 PM Alan Somers <
> > > > > >
> > > > > > asomers at freebsd.org> wrote:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Author: asomers
> > > > > > > > > > > > > > > > Date: Fri Sep 11 20:49:36 2020
> > > > > > > > > > > > > > > > New Revision: 365643
> > > > > > > > > > > > > > > > URL:
> > > > > > > > > > > > > > > >
> https://svnweb.freebsd.org/changeset/base/365643
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Log:
> > > > > > > > > > > > > > > > cp: fall back to read/write if
> > > > > > > > > > > > > > > > copy_file_range fails
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Even though copy_file_range has a file-
> > > > > > > > > > > > > > > > system agnostic
> > > > > >
> > > > > > version, it
> > > > > > > > > > > > > > > still
> > > > > > > > > > > > > > > > fails on devfs (perhaps because the file
> > > > > > > > > > > > > > > > descriptor is
> > > > > >
> > > > > > non-seekable?)
> > > > > > > > > > > > > > > In
> > > > > > > > > > > > > > > > that case, fallback to old-fashioned
> > > > > > > > > > > > > > > > read/write. Fixes
> > > > > > > > > > > > > > > > "cp /dev/null /tmp/null"
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Hi,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Any objection to adding a quick UPDATING
> > > > > > > > > > > > > > > entry for this?
> > > > > >
> > > > > > I'm seeing
> > > > > > > > > > > > > > > occasional reports of this breakage as recent
> > > > > > > > > > > > > > > as today on
> > > > > >
> > > > > > IRC from
> > > > > > > > > > > > > > > folks that were a little bit thrown off by
> > > > > > > > > > > > > > > this because it
> > > > > >
> > > > > > throws up
> > > > > > > > > > > > > > > fairly far into the build and looks like a
> > > > > > > > > > > > > > > stand build
> > > > > >
> > > > > > regression
> > > > > > > > > > > > > > > instead of a cp regression.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Kyle Evans
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > No objection. Can you suggest the proper
> > > > > > > > > > > > > > wording?
> > > > > > > > > > > > > > _______________________________________________
> > > > > > > > > > > > > > svn-src-all at freebsd.org mailing list
> > > > > > > > > > > > > >
> > https://lists.freebsd.org/mailman/listinfo/svn-src-all
> > > > > > > > > > > > > > To unsubscribe, send any mail to "
> > > > > >
> > > > > > svn-src-all-unsubscribe at freebsd.org"
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > --
> > > > > > > > > > > > > Mateusz Guzik <mjguzik gmail.com>
> >
>
More information about the svn-src-head
mailing list