Re: About close() in commit_lock_file()
- From
Duy Nguyen <pclouds@gmail.com>
- Date
- Aug 6, 2013, 08:36 UTC
- Message-ID
- <CACsJy8DquJj1qVawKfrbZY+2WLC54Gskizs1sxZ_j1yutBkbdA@mail.gmail.com>
- In-Reply-To
- <52009A90.7050701@viscovery.net>
On Tue, Aug 6, 2013 at 1:41 PM, Johannes Sixt <j.sixt@viscovery.net> wrote:
Show 16 quoted lines
> Am 8/5/2013 16:23, schrieb Duy Nguyen: >> close() is added in commit_lock_file(), before rename(), by 4723ee9 >> (Close files opened by lock_file() before unlinking. - 2007-11-13), >> which is needed by Windows. But doesn't that create a gap between >> close() and rename() on other platforms where another process can >> replace .lock file with something else before rename() is executed? > > First, files manipulated by commit_lock_file() are to be opened only using > lock_file() by definition. Opening such a file in with open() or fopen() > or renaming it via rename() without using the lockfile.[ch] API is > possible regardless of whether commit_lock_file() has closed the file or > not. Such manipulation is already undefined behavior (from Git's point of > view), and there is nothing we can do about "misbehaving" processes. > > Second, lock_file() uses O_CREAT|O_EXCL, which fails when the file exists, > regardless of whether it is open or not.
The second process could unlink(.lock file) first, then open it, even using lock_file(), but I think that falls into your "first" and is an invalid case from git point of view, so..
> Conclusion: There is no problem.
Agreed. False alarm.
-- Duy