Re: [msysGit] Re: [PATCH] mingw: do not crash on open(NULL, ...)

[Pat Thoyts <patthoyts@gmail.com>]

On 27 September 2010 14:19, Erik Faye-Lund <kusmabite@gmail.com> wrote:
> On Fri, Sep 24, 2010 at 12:50 AM, Junio C Hamano <gitster@pobox.com> wrote:
>> Erik Faye-Lund <kusmabite@gmail.com> writes:
>>
>>> On Thu, Sep 23, 2010 at 10:35 AM, Erik Faye-Lund <kusmabite@gmail.com> wrote:
>>>> Since open() already sets errno correctly for the NULL-case, let's just
>>>> avoid the problematic strcmp.
>>>>
>>>> Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
>>>
>>> I guess I should add a comment as to why this patch is needed:
>>>
>>> This seems to be the culprit for issue 523 in the msysGit issue
>>> tracker: http://code.google.com/p/msysgit/issues/detail?id=523
>>>
>>> fetch_and_setup_pack_index() apparently pass a NULL-pointer to
>>> parse_pack_index(), which in turn pass it to check_packed_git_idx(),
>>> which again pass it to open(). This all looks intentional to my
>>> (http.c-untrained) eye.
>>
>> Surely, open(NULL) should be rejected by a sane system, and your patch
>> looks sane to me.
>>
>
> Since this doesn't seem to be in git.git yet, perhaps you could squash
> this on top? I didn't notice it in time, but fopen lacked the same
> check (freopen already had the check). It's not as important, because
> it doesn't seem like we have any code reaching this path so far, but
> it would IMO be better to fix this now rather than having to chase
> down the issue again later...
>
> diff --git a/compat/mingw.c b/compat/mingw.c
> index 4595aaa..f069fea 100644
> --- a/compat/mingw.c
> +++ b/compat/mingw.c
> @@ -160,7 +160,7 @@ ssize_t mingw_write(int fd, const void *buf, size_t count)
>  #undef fopen
>  FILE *mingw_fopen (const char *filename, const char *otype)
>  {
> -       if (!strcmp(filename, "/dev/null"))
> +       if (filename && !strcmp(filename, "/dev/null"))
>                filename = "nul";
>        return fopen(filename, otype);
>  }
>

I'll apply this to the devel branch and try to remember to squash it
on the next rebase-merge.
Cheers,
Pat