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From: campbell@maynard.UUCP (Larry Campbell)
Newsgroups: net.unix-wizards
Subject: Re: Re: truncating a file opened via open()
Message-ID: <126@maynard.UUCP>
Date: Wed, 19-Jun-85 08:03:49 EDT
Article-I.D.: maynard.126
Posted: Wed Jun 19 08:03:49 1985
Date-Received: Sun, 23-Jun-85 08:38:41 EDT
References: <340@cmu-cs-edu1.ARPA> <786@turtlevax.UUCP> <217@luke.UUCP> <2315@sun.uucp>
Organization: The Boston Software Works Inc., Maynard, MA
Lines: 24

> > >In article <340@cmu-cs-edu1.ARPA> hua@cmu-cs-edu1.ARPA (Ernest Hua) writes:
> > >>Does anyone have any idea how to truncate a file at the current point in
> > >>writing if it is opened by open()?
> 
> There are precisely two solutions for non-4.2BSD systems:
> 1) implement (f)truncate on your system...

Kind of tough for people without source licenses (I know, I'm whining).

> 2) Copy the entire file, up to the point of truncation, to a temporary file,
> then copy it back to the original file.
>
> 	Guy Harris

I don't see how this works unless you unlink the file and then re-creat
it before writing it back.  But the original question implied you only had
a descriptor for the file, not a name...  so you can't unlink or re-creat
it.  And even if you knew the name, other links wouldn't get truncated.
Sounds like it's pretty tough to fake this one ...  sigh ...

- Larry Campbell
  The Boston Software Works, Inc., 120 Fulton St., Boston MA 02109
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