Date: Fri, 08 Jun 2001 02:11:07 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: "Patrick W. Penzias Dirks" <pwd@apple.com> Cc: FreeBSD-FS@FreeBSD.ORG, FreeBSD-Arch@FreeBSD.ORG Subject: Re: Support for pivot_root-like system call? Message-ID: <3B2096AB.309B2D14@mindspring.com> References: <200106072103.f57L37l26327@scv2.apple.com>
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"Patrick W. Penzias Dirks" wrote: > > Hi, > > I'm the filesystems tech lead in Apple's Mac OS X Core OS group. > Prompted by the needs of, among others, virus protection software > developers who want to be able to mount "on" the root directory to > intercept ALL filesystem calls in the system, I'm contemplating > implementation of a new system call in Mac OS X to do something like > Linux's pivot_root system call: > > int pivot_root(const char *new_root, const char *put_old); > > (which basically installs "new_root" as the new "/" [root_vnode] in > the system and transfers the current root directory to the pathname > specified my "put_old") It doesn't work in FreeBSD proper because of cache coherency bugs that have been around since 1995, but: mount -t nullfs / /put_old # or wherever mount -t <whatever> / Would do what you want, I think. Really, the BSD way of doing this is to stack an FS with the feature you want on top of the one without the feature in it. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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