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From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.unix.wizards,comp.sources.wanted
Subject: Re: ftruncate(2) for System V.3.2 needed
Message-ID: <2246@auspex.auspex.com>
Date: 17 Jul 89 17:55:50 GMT
References: <1132@ssp15.idca.tds.philips.nl> <02KJ02SJ3cms01@amdahl.uts.amdahl.com> <747@rwing.UUCP>
Reply-To: guy@auspex.auspex.com (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 24

>This ioctl() call looks like something that would be interesting to
>try, however, the value of F_FREESP is not to be found in *ANY* of the
>includes on my site - could someome perhaps indicate what numerical
>value F_FREESP is supposed to be on USG type systems?

The value that's defined in <fcntl.h>.  If it's not defined there, your
system may not *have* such an "fcntl()" call (not "ioctl()") - it first
appeared in some flavor of S5R3.1, isn't in S5R3 (or S5R2 or earlier),
and in S5R3.1 the code that implements it has the comments:

/*
 * This is an experimental facility for SVR3.1 and WILL be changed
 * in the next release.  ...
 *

	...

 * Bug:  unused bytes in the last retained block are not cleared.
 * This may result in a "hole" in the file that does not read as zeroes.
 */

so beware - if it's not documented, it may be because it's not
considered "done" and may not be supported or even work correctly in all
cases....