Re: seekable pipes

>> But I'd expect it to do all of the open file operations, not just seek. 
(A 
>> seek-only implementation is certainly acceptable, but the structure 
should 
>> be for the whole concept).
>
>Like ... ioctl, flock? What else isn't implementable in terms of read,
>write, seek?

I guess most of the open file operations can't be moved to user space 
(mmap, readv, etc.).  Looking at the list (of VFS operations), I see read, 
write, seek, ioctl, flock, lock, fsync, and flush that could sensibly be 
transported across a pipe.

>The stat type for <() files is "character special"

When I do it, it's "FIFO" (st_mode contains S_IFIFO).

>such files are usually seekable.

Really?  Character device special files are usually not in my experience: 
terminals, tapes, serial ports.

>In any case, emacs and vim are cool.

You can edit a device special file?  Emacs gives me "file cannot be read" 
on various pipe and character device special files I tried.  strace shows 
that it does an lstat(), then gives up.

--
Bryan Henderson                     IBM Almaden Research Center
San Jose CA                         Filesystems

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