Re: [PATCH v3 0/2] Brown-bag fix on top of js/mingw-inherit-only-std-handles

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Dec 3, 2019, 12:04 UTC
Message-ID: <nycvar.QRO.7.76.6.1912031303250.31080@tvgsbejvaqbjf.bet>
In-Reply-To: <a4ac4530-9b5c-3eb6-ada2-067c6ef73868@kdbg.org>

Hi Hannes,

On Mon, 2 Dec 2019, Johannes Sixt wrote:

Show 13 quoted lines

> Am 02.12.19 um 12:33 schrieb Johannes Schindelin via GitGitGadget:
> > Range-diff vs v2:
> >
> >  1:  280b6d08a4 = 1:  280b6d08a4 mingw: do set `errno` correctly when trying to restrict handle inheritance
> >  2:  c3dea00fb1 ! 2:  e04e1269b3 mingw: translate ERROR_SUCCESS to errno = 0
> >      @@ -3,12 +3,15 @@
> >           mingw: translate ERROR_SUCCESS to errno = 0
>
> The subject line would have to be adjusted as well.
>
> 	mingw: forbid translating ERROR_SUCCESS to an errno value
>
> or something.

Oy. Thank you for catching this! (It is always amazing to me how much I miss when I have stared at the same commits for a while.)

For good measure, I force-pushed the branch of the PR to match what Junio has in `pu`, but if there are no other changes I need to make, I will refrain from submitting another iteration.

Thanks, Dscho

Show 33 quoted lines

>
> >
> >           Johannes Sixt pointed out that the `err_win_to_posix()` function
> >      -    mishandles `ERROR_SUCCESS`. This commit fixes that.
> >      +    mishandles `ERROR_SUCCESS`: it maps it to `ENOSYS`.
> >
> >      -    Technically, we try to only assign `errno` to the corresponding value of
> >      -    `GetLastError()` (which translation is performed by that function) when
> >      -    a Win32 API call failed, so this change is purely defensive and is not
> >      -    expected to fix an existing bug in our code base.
> >      +    The only purpose of this function is to map Win32 API errors to `errno`
> >      +    ones, and there is actually no equivalent to `ERROR_SUCCESS`: the idea
> >      +    of `errno` is that it will only be set in case of an error, and left
> >      +    alone in case of success.
> >      +
> >      +    Therefore, as pointed out by Junio Hamano, it is a bug to call this
> >      +    function when there was not even any error to map.
> >
> >           Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> >
> >      @@ -19,7 +22,7 @@
> >        	case ERROR_SHARING_BUFFER_EXCEEDED: error = ENFILE; break;
> >        	case ERROR_SHARING_VIOLATION: error = EACCES; break;
> >        	case ERROR_STACK_OVERFLOW: error = ENOMEM; break;
> >      -+	case ERROR_SUCCESS: error = 0; break;
> >      ++	case ERROR_SUCCESS: BUG("err_win_to_posix() called without an error!");
> >        	case ERROR_SWAPERROR: error = ENOENT; break;
> >        	case ERROR_TOO_MANY_MODULES: error = EMFILE; break;
> >        	case ERROR_TOO_MANY_OPEN_FILES: error = EMFILE; break;
> >
>
> -- Hannes
>