Xref: utzoo comp.unix.wizards:15504 comp.unix.questions:12794
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!xanth!kremer
From: kremer@cs.odu.edu (Lloyd Kremer)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: unix question: files per directory
Summary: why is off_t signed?
Keywords: how many can there be?
Message-ID: <8420@xanth.cs.odu.edu>
Date: 11 Apr 89 23:12:40 GMT
References: <24110@beta.lanl.gov>
Followup-To: comp.unix.wizards
Distribution: na
Organization: Old Dominion University, Norfolk, Va.
Lines: 34



In article <24110@beta.lanl.gov> dxxb@beta.lanl.gov (David W. Barts) writes:
>How many files can there be in a single UNIX directory

In article <16839@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
>The maximum size is the same as for files, namely 2^31 - 1 (2147483647)
>bytes.  (This is due to the use of a signed 32 bit integer for off_t.


Point of curiosity:

Why was it decided that off_t should be signed?  Why should it not be
unsigned long where unsigned longs are supported, or unsigned int where int
is a 32 bit quantity?  It seems that signed long imposes an unnecessary
2GB limit on file size.

There are many devices having a capacity greater than 4 or 5 GB.  It seems
reasonable that one might want a file greater than 2GB on such a device,
such as the product of something akin to 'tar -cf' of a whole filesystem.

And it doesn't make sense to have a negative offset into a file.  The
only exception that comes to mind is that of returning an error code from
a function like lseek(), and this special case could be macro'd like

	#define SEEK_ERR ((off_t)(-1))

in <sys/types.h> or <sys/stat.h>.

					Just curious,

					Lloyd Kremer
					Brooks Financial Systems
					{uunet,sun,...}!xanth!brooks!lloyd