Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!bruce!cechew
From: cechew@bruce.cs.monash.OZ.AU (Earl Chew)
Newsgroups: comp.os.minix
Subject: Re: fs "bug" (rename) and "fix"
Keywords: fs rename
Message-ID: <3404@bruce.cs.monash.OZ.AU>
Date: 28 Nov 90 01:57:42 GMT
References: <1990Nov28.001925.24250@unicorn.cc.wwu.edu>
Organization: Monash Uni. Computer Science, Australia
Lines: 50

In <1990Nov28.001925.24250@unicorn.cc.wwu.edu> phil@unicorn.cc.wwu.edu (Phil Nelson) writes:

>Recently, I was working with a program that used the rename system call
>to make backup files.  It used calls like rename("file","file~").  This
>call failed every time.  After tracking down what was happening, I
>discovered that fs (the code for rename) checks to make sure that the
>old file name (file) is not a prefix of the new file name (file~).  If

Actually, there is a problem with both the original and the proposed patch.
Assume that the cwd is /a and that there is a directory named /a/b. Consider:

	rename("b","b~");	/* failed original */
	rename("b","/a/b/c");	/* fails proposed patch */

It may get worse once symbolic links are introduced. Enclosed is a copy of a
patch that Bruce sent me that appears to cure the problem.

Earl

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-- 
Earl Chew, Dept of Computer Science, Monash University, Australia 3168
EMAIL: cechew@bruce.cs.monash.edu.au PHONE: 03 5655447 FAX: 03 5655146
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