Re: Bug: git branch --unset-upstream command can nuke config when disk is full.

From: Jeff King <peff@peff.net>
Date: Sep 13, 2017, 14:51 UTC
Message-ID: <20170913145154.423zqe6antzccclk@sigill.intra.peff.net>
In-Reply-To: <CANgJU+WHr2-FjAUUKQ8pUkniczcxrr11dTo_zBeXdTi_su2oUA@mail.gmail.com>

On Wed, Sep 13, 2017 at 04:49:45PM +0200, demerphq wrote:

Show 19 quoted lines

> On 13 September 2017 at 16:17, Jeff King <peff@peff.net> wrote:
> > You're welcome to read over the function to double-check, but I just
> > looked it over and couldn't find any unchecked writes.
> 
> I can look, but I doubt I would notice something you did not.
> 
> On the other hand the strace output does show that this is a case
> where the writes failed, but we still renamed the empty config.lock
> file into place:
> 
> 
> write(3, "[core]\n\tsharedRepository = true\n"..., 288) = -1 ENOSPC
> (No space left on device)
> write(3, "        merge = refs/heads/yves/"..., 51) = -1 ENOSPC (No
> space left on device)
> munmap(0x7f48d9b8c000, 363)             = 0
> close(3)                                = 0
> rename("/usr/local/git_tree/main/.git/config.lock",
> "/usr/local/git_tree/main/.git/config") = 0

Hmph. That is very disturbing. But with that information I should be able to track down the culprit. Thanks for digging.

> I freed up space and things worked, so I somehow doubt the filesystem
> is at fault. When I then filled up the disk and retried the error was
> repeatable.

Yeah, agreed. This really does look like a bug.

-Peff