linux-kernel - unexpected rename() behaviour

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Date:	Sat, 29 Mar 2008 01:07:52 +0100
From:	Ketil Froyn <ketil@...yn.name>
To:	linux-kernel@...r.kernel.org
Subject: unexpected rename() behaviour

Hi,

The following behaviour was unexpected (tested on Debian/ext3):

$ echo 1 > 1
$ ln 1 2
$ cat 2
1
$ ./rename 2 1
$ echo $?
0
$ cat 2
1

The code for ./rename is simple:

---
/* compile: gcc -o rename rename.c */
#include <stdio.h>
int main(int argc, char *argv[]) { return rename(argv[1], argv[2]); }
---

I thought this must be wrong behaviour, but I have been unable to 
confirm what the correct result should be in this special case. rename() 
returns success, but the source file is intact, which seems odd. The 
"mv" command specifically checks for cases like this and calls 
unlink("2") instead of rename("2", "1"). Are all applications meant to 
do this? What standards describe what rename() should do in cases like this?

Regards,
Ketil Froyn
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