Date: Sat, 4 Nov 2006 18:22:39 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Joerg Pernfuss <elessar@bsdforen.de>, <freebsd-hackers@freebsd.org> Subject: Re: [patch] rm can have undesired side-effects Message-ID: <200611050222.kA52Mdm0011497@apollo.backplane.com> References: <20061029222847.GA68272@marvin.astase.com> <20061030003628.42bc5f8d@loki.starkstrom.lan> <00f201c6fbb6$0c6bd150$b3db87d4@multiplay.co.uk> <20061030024358.39a12359@loki.starkstrom.lan>
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::...
::Although I am a big defender of "the user should know what he does",
::the "right thing to do"[TM] would probably be to sync the behaviour
::of FreeBSD's rm(1) to OpenBSD and lobby NetBSD and DragonFlyBSD to do
::the same :)
::
:: Joerg
:
: I agree. I will make this change in DragonFly right now, in fact.
: The -P option really needs to be consistent across environments
: and my take on the original design was so users could alias rm to
: rm -P in their .cshrc files. Clearly it cannot destroy the contents
: of the file in the presence of hard links when used in that context.
:
: -Matt
Followup note here. OpenBSD's /bin/rm source is doing something
unexpected... it isn't unlink()ing the file if it has > 1 hardlinks
and -P is used. That is its current behavior.
pkgbox# /usr/obj/archive/OpenBSD-current/src/bin/rm/rm -P /tmp/x
pkgbox# echo "x" > /tmp/x
pkgbox# ln /tmp/x /tmp/y
pkgbox# /usr/obj/archive/OpenBSD-current/src/bin/rm/rm -P /tmp/x
rm: /tmp/x (inode 36): not overwritten due to multiple links
pkgbox# ls -la /tmp/x /tmp/y
-rw-r--r-- 2 root wheel 2 Nov 4 18:19 /tmp/x
-rw-r--r-- 2 root wheel 2 Nov 4 18:19 /tmp/y
pkgbox#
I'm not sure I agree with this. It makes -P unusable as a .cshrc alias.
I would have expected it to still unlink the file.
In anycase, for now I am going to sync DragonFly's rm with OpenBSD anyhow,
even though I'm scratching my head a bit. This may be just as broken
as before, just in a different (and safer) way.
-Matt
Matthew Dillon
<dillon@backplane.com>
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