On Thursday, February 03, 2011 03:15:29 pm roger peppe wrote:
> On 3 February 2011 13:44, dexen deVries <dexen.devr...@gmail.com> wrote:
> > On Thursday, February 03, 2011 02:36:40 pm roger peppe wrote:
> >> On 3 February 2011 11:45, dexen deVries <dexen.devr...@gmail.com> wrote:
> >> > read(open("/foo")) returns byte stream under entry `foo' in the root
> >> > object.
> >> >
> >> > readdir("/foo") returns `bar' (and possibly others) -- entries in
> >> > hierarchical section of object `/foo'.
> >>
> >> there's no distinction between readdir and read in plan 9.
> >
> > Forgot about that. Still, you can't chdir() into an inode that doesn't
> > indicate being a directory. And the bytestream returned by
> > read(SOME_DIRECTORY) is fixed-format and doesn't provide any space for
> > free- form bytestream.
>
> i don't think that helps you.
>
> under plan 9, reading a directory is this:
>
> translate(read(open(dir)))
>
> i don't see how you can make read(open(dir)) return
> something different.
no contest there. I'd like to have a look at the handling of multiple forks of
files in other OSes (from userland perspective).
> oh yes, maintaining the usual semantics for cp becomes tricky.
>
> mkdir z
> cp x.c z
>
> do i mean to write x.c to z itself, or to a new file within z?
I have only linux experience with cp -- and this usage pattern always irked
me. Theoretically, it's prone to race condition: suppose somebody removes the
dir `z' right between `mkdir' and `cp'. You `cp x.c z', and end up with `z'
file. It's unpredictable, unless you're on a single-process OS (yuck).
I'd rather see `cp x.c z' always duplicates bytestream from x.c into z's
bytestream, whatever `z' happens to be right now. Creating `z' in the process,
if not present. If you want to have `z/x.c', you'd state that explicitly as
`cp x.c z/x.c'.
nb., with the current semantics you *could* say `cp x.c z/' to be unambiguous
you want to create a child of `z', but it seems to be common not to use
trailing slash unless 100% necessary.
--
dexen deVries
[[[↓][→]]]
> how does a C compiler get to be that big? what is all that code doing?
iterators, string objects, and a full set of C macros that ensure
boundary conditions and improve interfaces.
ron minnich, in response to Charles Forsyth
http://9fans.net/archive/2011/02/90
