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Re: keychain locking problem (Was test -f occasionally fails on sym links)
On Mar 29 06:47, Karl M wrote:
> The reason I ask is that keychain uses
>
> if tl_error=`ln -s $$ "$lockf" 2>&1`; then
>
> inside its takelock function as an atomic operation for creating a lock. It
> then uses
>
> if [ -f "$lockf" ]; then
>
> to test for an old style lock file, and this sometimes fails (incorrectly
> succeeds) and generates an error message.
>
> >From what I can find, this is expected to be an atomic operation and one
> >of
> the ways programs do file locking.
No chance. Cygwin is not the OS and the OS doesn't support native symlinks
and consequentially no atomic symlink creation.
> if (umask 0377; : > ~/.keychain/${HOSTNAME}-keys) 2>/dev/null; then
> keychain --quiet ~/.ssh/identity ~/.ssh/id_dsa ~/.ssh/id_rsa
> fi
>
> and the lock file is cleaned up by the keychain-service. This does seem to
> be safe (only verified by load testing under Cygwin). I found this method
> in the UNIX CD Bookshelf.
>
> So...my questions are
>
> 1) Is this a safe method?
Yes, AFAICS. File creation and setting of permissions is atomic, as
long as you don't rely on "ntea". But that's old stuff, just ignore it.
> 3) Should this problem be fed to the upstream keychain maintainer?
The symlink creation problem? If the upstream maintainer cares, sure.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader mailto:cygwin@cygwin.com
Red Hat, Inc.
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