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Re: casefile implementation
From: |
Ben Pfaff |
Subject: |
Re: casefile implementation |
Date: |
Mon, 30 May 2005 19:10:55 -0700 |
User-agent: |
Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) |
John Darrington <address@hidden> writes:
> I wondered if it wouldn't be possible to use the mmap system call to
> greatly simplify the implementation of casefile.c
I don't want to depend on mmap. It's not available everywhere,
and even where it is it might not work on every file system.
The GNU coding standards address this:
Don't assume that `mmap' either works on all files or fails for all
files. It may work on some files and fail on others.
The proper way to use `mmap' is to try it on the specific file for
which you want to use it--and if `mmap' doesn't work, fall back on
doing the job in another way using `read' and `write'.
The reason this precaution is needed is that the GNU kernel (the
HURD) provides a user-extensible file system, in which there can be many
different kinds of "ordinary files." Many of them support `mmap', but
some do not. It is important to make programs handle all these kinds
of files.
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