From: Eric Sunshine <sunshine@sunshineco.com>
Date: Wed, 17 Aug 2016 12:48:37 GMT
Subject: Re: [PATCH 2/2] mingw: ensure temporary file handles are not inherited by child processes
Message-ID: <CAPig+cR4=kEUb5PsZfoz3=W+R61wER=vHos5uX02kEVM8YETgA@mail.gmail.com>
In-Reply-To: <77e7c4e4de6c45a1b24bb4d08ca20a1385f43444.1471437637.git.johannes.schindelin@gmx.de>

On Wed, Aug 17, 2016 at 8:41 AM, Johannes Schindelin
<johannes.schindelin@gmx.de> wrote:
> When the index is locked and child processes inherit the handle to
> said lock and the parent process wants to remove the lock before the
> child process exits, on Windows there is a problem: it won't work
> because files cannot be deleted if a process holds a handle on them.
> The symptom:
>
>     Rename from 'xxx/.git/index.lock' to 'xxx/.git/index' failed.
>     Should I try again? (y/n)
>
> Spawning child processes with bInheritHandles==FALSE would not work
> because no file handles would be inherited, not even the hStdXxx
> handles in STARTUPINFO (stdin/stdout/stderr).
>
> Opening every file with O_NOINHERIT does not work, either, as e.g.
> git-upload-pack expects inherited file handles.
>
> This leaves us with the only way out: creating temp files with the
> O_NOINHERIT flag. This flag is Windows-specific, however. For our
> purposes, it is equivalent our purposes) to O_CLOEXEC (which does not

s/our purposes)//

> exist on Windows), so let's just open temporary files with the
> O_CLOEXEC flag and map that flag to O_NOINHERIT on Windows.
>
> This fixes the test that we just introduced to demonstrate the problem.
>
> Signed-off-by: Ben Wijen <ben@wijen.net>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>