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Date: Fri, 10 Dec 2010 20:22:06 +0100
From: Matthias Andree <matthias DOT andree AT gmx DOT de>
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To: cygwin AT cygwin DOT com
Subject: Re: 1.7.7: rm -rf sometimes fails - race condition?
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Am 10.12.2010 19:26, schrieb Christopher Faylor:
> On Fri, Dec 10, 2010 at 06:49:09PM +0100, Matthias Andree wrote:
>>Greetings,
>>
>>I see that "rm -rf" on a directory sometimes fails, like here:
>>
>>|>>> Creating source package
>>| fetchmail-6.3.19-1.cygport
>>| fetchmail-6.3.19-1.cygwin.patch
>>| fetchmail-6.3.19.tar.bz2
>>|>>> Removing work directory in 5 seconds...
>>|>>> Removing work directory NOW.
>>| rm: cannot remove `/usr/src/fetchmail-6.3.19-1/inst/usr/share/locale/da':
>>Directory not empty
>>| Command exited with non-zero status 1
>>
>>Alternatively, you get "...in use" for an error, however, in this case, it
>>appears that the corresponding syscall triggered by rm(1) had already returned
>>but the file wasn't fully removed from the directory yet.
>>
>>I've seen this happen for a while now.  This happens sporadically, and retrying
>>the operation usually succeeds, so it matters less in an interactive shell.
>>However, this often breaks scripts, in this case, cygport.
>>
>>This looks like either a premature return from a syscall or libcall, or like a
>>genuine race in the system.
>>
>>In case it matters, this is
>>- Windows 7 Prof. 32-bit German
>>- with Sophos Endpoint Security and Control ver. 9 and
>>- Microsoft Windows Defender.
>>- coreutils 8.5-2
>>- uname -a:
>>  CYGWIN_NT-6.1 somehost 1.7.7(0.230/5/3) 2010-08-31 09:58 i686 Cygwin
>>
>>
>>Has anyone seen similar things?
> 
> Yes and you seem to have nailed the problem - it happens when a virus checker
> hooks into a syscall and allows it to return before completion.  I don't think
> we want to modify Cygwin to not trust success return values from system calls.

Well, I don't know a solution but I think this is unexpected behaviour.

You can delete thousands of files and dirs without bad things happening, but
once in a while it fails.  What file of the many (cvsweb isn't really amenable
to searches ;-)) implements unlink()?

-- 
Matthias Andree

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