From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B9677C433F5 for ; Thu, 21 Apr 2022 12:24:03 +0000 (UTC) Received: from localhost ([::1]:44310 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nhVqs-0005ew-LP for qemu-devel@archiver.kernel.org; Thu, 21 Apr 2022 08:24:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43814) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nhVnu-0002kW-31; Thu, 21 Apr 2022 08:20:58 -0400 Received: from kylie.crudebyte.com ([5.189.157.229]:49191) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nhVnr-0005ZS-DJ; Thu, 21 Apr 2022 08:20:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=kylie; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Content-ID:Content-Description; bh=g6fePjwJIu7uKmkrQQL+/eH1tsubc6Gw7nyXI8zSugk=; b=bWFF5XoDUD5EturrXXXNXyNlcl N5ACHBra24IXxi0CmV0oSwMPCBp8UsTVo2d4CGiNltMAYpYuHqKVaXS7HYLtxS/nrzom41cFSLHLT IXoCvEIB95X7+4KUVMk/boezz6nD2cGGSMGRjBRtrGVlzbZ03AuAcQrCttDxyWdJSJo62cPRYyar8 w5PvwoyGi537FXhAbMSi2XfkvRsc0xyGsPyAIkB7YhSYmk6ZyMygL09QApyVH/fiQmAnQIPXInv4U 94tB4/CuPvOsiSLYB15sLNdVxeZqas/vf9+Fdj4UnFBGY1vKtkXH/f3z75D0ZxcmmzBNCn1E8GCN8 yVqaNyOYU8ehyBcWmL+1/pfbmr8POOSLFS9QEC68rMglFrIpA5FLZ4e3qkdajgI0ezAv+kSZ5rttI qvVHIWdlbR8PVE1gFxSRZBinwa4swr3cd/17TS22ApTNInvZWqcC99nCvQTdF1Jg/bvOT+tfffnKI F7mKWC4hJEis/4id5018pUyfEpqY5Ujg3OdYGWmBhLRZuysBtOlngoQyLl9G3W2tVatRzPYZkUM1I vD3yTJQkQi68z6MgStqPRxqE+CcUf5LKMFIrr6i/RDylRJGhJMf1tcchFpLVAM7NwTPazvgwnpThe 9l+EVqze21pK7vVYlov8fIHVYJS5lY3w4s88gPiN4=; From: Christian Schoenebeck To: qemu-devel@nongnu.org, qemu-stable@nongnu.org Cc: Keno Fischer , Michael Roitzsch , Will Cohen , Akihiko Odaki , Greg Kurz Subject: Re: [PATCH 4/5] 9pfs: fix wrong errno being sent to Linux client on macOS host Date: Thu, 21 Apr 2022 14:20:50 +0200 Message-ID: <2789542.yvXY0umSai@silver> In-Reply-To: <20220421134626.52726efa@bahia> References: <3250585.T8RbiGE4XJ@silver> <20220421134626.52726efa@bahia> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Received-SPF: pass client-ip=5.189.157.229; envelope-from=qemu_oss@crudebyte.com; helo=kylie.crudebyte.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Donnerstag, 21. April 2022 13:46:26 CEST Greg Kurz wrote: > On Thu, 21 Apr 2022 13:13:08 +0200 > > Christian Schoenebeck wrote: > > On Donnerstag, 21. April 2022 12:48:35 CEST Greg Kurz wrote: > > > On Tue, 19 Apr 2022 13:41:59 +0200 > > > > > > Christian Schoenebeck wrote: > > > > Linux and macOS only share some errno definitions with equal macro > > > > name and value. In fact most mappings for errno are completely > > > > different on the two systems. > > > > > > > > This patch converts some important errno values from macOS host to > > > > corresponding Linux errno values before eventually sending such error > > > > codes along with Tlerror replies (if 9p2000.L is used that is), which > > > > fixes a bunch of misbehaviours when running a Linux client on macOS > > > > host. > > > > > > This even fixes an actual protocol violation : > > > > > > lerror -- return error code > > > > > > size[4] Rlerror tag[2] ecode[4] > > > > > > lerror replaces the reply message used in a successful call. ecode is a > > > numerical Linux errno. > > > ^^^^^^^^^^^^^^^^^^^^^ > > > > > > Taken from > > > https://github.com/chaos/diod/wiki/protocol#lerror----return-error-code > > > > Again, something to add to the commit log? > > IMHO a protocol violation is important enough to be mentioned but > I'll leave it to you. Ok, will do. > > > > For instance this patch fixes: > > > > mount -t 9p -o posixacl ... > > > > > > > > on Linux guest if security_mode=mapped was used for 9p server, which > > > > refused to mount successfully, because macOS returned ENOATTR==93 > > > > when client tried to retrieve POSIX ACL xattrs, because errno 93 > > > > is defined as EPROTONOSUPPORT==93 on Linux, so Linux client believed > > > > that xattrs were not supported by filesystem on host in general. > > > > > > > > Signed-off-by: Christian Schoenebeck > > > > --- > > > > > > > > hw/9pfs/9p.c | 27 +++++++++++++++++++++++++++ > > > > 1 file changed, 27 insertions(+) > > > > > > > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > > > > index d953035e1c..becc41cbfd 100644 > > > > --- a/hw/9pfs/9p.c > > > > +++ b/hw/9pfs/9p.c > > > > @@ -57,6 +57,31 @@ enum { > > > > > > > > P9ARRAY_DEFINE_TYPE(V9fsPath, v9fs_path_free); > > > > > > > > +/* Translates errno from host -> Linux if needed */ > > > > +static int errno_to_dotl(int err) { > > > > +#if defined(CONFIG_LINUX) > > > > + /* nothing to translate (Linux -> Linux) */ > > > > +#elif defined(CONFIG_DARWIN) > > > > + /* translation mandatory for macOS hosts */ > > > > + if (err == ENAMETOOLONG) { > > > > + err = 36; /* ==ENAMETOOLONG on Linux */ > > > > + } else if (err == ENOTEMPTY) { > > > > + err = 39; /* ==ENOTEMPTY on Linux */ > > > > + } else if (err == ELOOP) { > > > > + err = 40; /* ==ELOOP on Linux */ > > > > + } else if (err == ENOATTR) { > > > > + err = 61; /* ==ENODATA on Linux */ > > > > + } else if (err == ENOTSUP) { > > > > + err = 95; /* ==EOPNOTSUPP on Linux */ > > > > + } else if (err == EOPNOTSUPP) { > > > > + err = 95; /* ==EOPNOTSUPP on Linux */ > > > > + } > > > > > > I'm assuming you have audited all errnos, right ? Just to be sure > > > that this won't bite anymore. > > > > Depends on what you mean with "all". Like I wrote in the commit log, for > > now I translated in this patch those errnos that I identified as > > important, and those are audited by me of course (checked the man pages > > for what errors are expected as result from calls on Linux vs. macOS side > > and looked up numeric values from header files on both sides, tests). > > I was pretty sure you'd have done that at least :-) > > > However if you rather mean really all errnos that were ever defined on > > Linux and macOS, then the answer is no. That would probably quite some > > work, and I'm not sure if you could just try to translate them dry, i.e. > > by just looking at the headers or something. > > But yes I was rather meaning the full errno set. > > > So yes, your concern is justified. The question is, should this all be > > translated right now already, or would it be OK to address this minimum > > set of errno translation for now (especially for qemu-stable) and then > > later address the rest? > > My concern is about the maintenance burden of investigating future > implementations of this issue, so I'd say it is mostly up to you > as the principal maintainer. Maybe leave a FIXME comment in the code > that the list of translated errnos isn't exhaustive at least ? I stick to this minimal approach with FIXME comment then for now. I have tested this patch thoroughly on macOS and did not encounter similar issues. So I think it is good enough as first-aid patch at least. The aforementioned case-insensitive filesystem issues are a higher priority from my PoV, because they trigger various misbehaviour in my tests. Best regards, Christian Schoenebeck > > On the long term you would probably import the Linux errno header file > > into > > the code base, then prefix the individual macros with something like > > DOTL_ENODATA, etc. and then use those macros for translating the errnos > > instead of using literal numerics, maybe using GCC's designated array > > initializers then. > > This would make sense indeed since 9p2000.L explicitly mentions the > numerical linux errnos. > > > > > +#else > > > > +#error Missing errno translation to Linux for this host system > > > > +#endif > > > > + return err; > > > > +} > > > > + > > > > > > As with the other patch, I'd rather move this magic to 9p-util.h . > > > > Makes sense. There is indeed already too much utility code piled up in > > 9p.c.> > > > > static ssize_t pdu_marshal(V9fsPDU *pdu, size_t offset, const char > > > > *fmt, > > > > ...) { > > > > > > > > ssize_t ret; > > > > > > > > @@ -1054,6 +1079,8 @@ static void coroutine_fn pdu_complete(V9fsPDU > > > > *pdu, > > > > ssize_t len)> > > > > > > > > } > > > > len += ret; > > > > id = P9_RERROR; > > > > > > > > + } else { > > > > + err = errno_to_dotl(err); > > > > > > > > } > > > > > > > > ret = pdu_marshal(pdu, len, "d", err);