From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.2 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_NONE,URIBL_SBL,URIBL_SBL_A shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id F0F7B1F464 for ; Fri, 29 Nov 2019 23:02:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727217AbfK2XCv (ORCPT ); Fri, 29 Nov 2019 18:02:51 -0500 Received: from bsmtp2.bon.at ([213.33.87.16]:44489 "EHLO bsmtp2.bon.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727073AbfK2XCv (ORCPT ); Fri, 29 Nov 2019 18:02:51 -0500 Received: from dx.site (unknown [93.83.142.38]) by bsmtp2.bon.at (Postfix) with ESMTPSA id 47Pqm84dJdz5tlB; Sat, 30 Nov 2019 00:02:48 +0100 (CET) Received: from [IPv6:::1] (localhost [IPv6:::1]) by dx.site (Postfix) with ESMTP id 2CCE91BFA; Sat, 30 Nov 2019 00:02:48 +0100 (CET) Subject: Re: [PATCH 1/1] mingw: do set `errno` correctly when trying to restrict handle inheritance To: Johannes Schindelin via GitGitGadget Cc: git@vger.kernel.org, Johannes Schindelin , Junio C Hamano References: <685360f735e35e837bc9ef684cbde33564c81666.1575063876.git.gitgitgadget@gmail.com> From: Johannes Sixt Message-ID: <52f2fe39-6a71-a327-8aea-ba757b7eec18@kdbg.org> Date: Sat, 30 Nov 2019 00:02:48 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <685360f735e35e837bc9ef684cbde33564c81666.1575063876.git.gitgitgadget@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Am 29.11.19 um 22:44 schrieb Johannes Schindelin via GitGitGadget: > From: Johannes Schindelin > > In 9a780a384de (mingw: spawned processes need to inherit only standard > handles, 2019-11-22), we taught the Windows-specific part to restrict > which file handles are passed on to the spawned processes. > > Since this logic seemed to be a bit fragile across Windows versions (we > _still_ support Windows Vista in Git for Windows, for example), a > fall-back was added to try spawning the process again, this time without > restricting which file handles are to be inherited by the spawned > process. > > In the common case (i.e. when the process could not be spawned for > reasons _other_ than the file handle inheritance), the fall-back attempt > would still fail, of course. > > Crucially, one thing we missed in that code path was to set `errno` > appropriately. > > This should have been caught by t0061.2 which expected `errno` to be > `ENOENT` after trying to start a process for a non-existing executable, > but `errno` was set to `ENOENT` prior to the `CreateProcessW()` call: > while looking for the config settings for trace2, Git tries to access > `xdg_config` and `user_config` via `access_or_die()`, and as neither of > those config files exists when running the test case (because in Git's > test suite, `HOME` points to the test directory), the `errno` has the > expected value, but for the wrong reasons. > > Let's fix that by making sure that `errno` is set correctly. > > It would be nice if we could somehow fix t0061 to make sure that this > does not regress again. One approach that seemed like it should work, > but did not, was to set `errno` to 0 in the test helper that is used by > t0061.2. > > However, when `mingw_spawnvpe()` wants to see whether the file in > question is a script, it calls `parse_interpreter()`, which in turn > tries to `open()` the file.0/compat/mingw.c#L1134. Obviously, Copy-and-paste garbage? > this call fails, and sets `errno` to `ENOENT`, deep inside the call > chain started from that test helper. > > Instead, we force re-set `errno` at the beginning of the function > `mingw_spawnve_fd()`, which _should_ be safe given that callers of that > function will want to look at `errno` if -1 was returned. And if that > `errno` is 0 ("No error"), regression tests like t0061.2 will kick in. > > Reported-by: Johannes Sixt > Signed-off-by: Johannes Schindelin > --- > compat/mingw.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/compat/mingw.c b/compat/mingw.c > index 2b6eca2f56..bb4eb4211a 100644 > --- a/compat/mingw.c > +++ b/compat/mingw.c > @@ -1423,6 +1423,9 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen > const char *(*quote_arg)(const char *arg) = > is_msys2_sh(*argv) ? quote_arg_msys2 : quote_arg_msvc; > > + /* Make sure to override previous errors, if any */ > + errno = 0; > + > if (restrict_handle_inheritance < 0) > restrict_handle_inheritance = core_restrict_inherited_handles; > /* > @@ -1580,8 +1583,8 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen > ret = CreateProcessW(*wcmd ? wcmd : NULL, wargs, NULL, NULL, > TRUE, flags, wenvblk, dir ? wdir : NULL, > &si.StartupInfo, &pi); > + errno = err_win_to_posix(GetLastError()); I think this should be protected by 'if (!ret)' because err_win_to_posix() does not handle ERROR_SUCCESS and turns it into ENOSYS. It's not that bad because in the case of success we do not guarantee any value of errno anyway. > if (ret && buf.len) { > - errno = err_win_to_posix(GetLastError()); > warning("failed to restrict file handles (%ld)\n\n%s", > err, buf.buf); > } > That said, this fixes the failure. -- Hannes