From patchwork Thu Oct 24 11:46:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Steinhardt X-Patchwork-Id: 13848830 Received: from fout-a7-smtp.messagingengine.com (fout-a7-smtp.messagingengine.com [103.168.172.150]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF4F4147C79 for ; Thu, 24 Oct 2024 11:46:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.150 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770388; cv=none; b=iKxScxb3/4WxjFb3coQncNqXA0xABEbIzdBNkO7mAzT61LiB5MlzGH1ZijyT8VDGt4Xt1/gWybB0dVsm5/JrUZ67Cr554fYsoCO7ORud+CdJSJiCbCmxFSRmqPE9LAdDiiPlc3A5hytBvE3f38UT4kPcVgis6NJIyTUFJjoL40k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770388; c=relaxed/simple; bh=YqXW1DFZbq/8XaUQc83doprlyCXcqO0C2mKsYzs3Fh0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I/gD0HUy3P4Bc1U8BuiqqnlzW7YLAlYTa3JHX2hfz+yiJ+ZPASJlIyEWQ4ACkR1Uz9tz6p52a3GVnJwlKCyuLlS/LYHLqitnavk5XlO93Ea0+67bzfgE1L0gBUgwJNrD6Z1e0POhcG1QVRoUvsZXyK3IlKOu/VxK9Ori7yQLFUc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=pks.im; spf=pass smtp.mailfrom=pks.im; dkim=pass (2048-bit key) header.d=pks.im header.i=@pks.im header.b=KiQ3ebxU; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=I5WyukWA; arc=none smtp.client-ip=103.168.172.150 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=pks.im Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pks.im Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pks.im header.i=@pks.im header.b="KiQ3ebxU"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="I5WyukWA" Received: from phl-compute-07.internal (phl-compute-07.phl.internal [10.202.2.47]) by mailfout.phl.internal (Postfix) with ESMTP id E173A13800D4; Thu, 24 Oct 2024 07:46:24 -0400 (EDT) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-07.internal (MEProxy); Thu, 24 Oct 2024 07:46:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pks.im; h=cc:cc :content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:subject :subject:to:to; s=fm3; t=1729770384; x=1729856784; bh=MTRkXvw6t0 FSqOMZZJW27DpDqfh6nWVWSPW17/JpGEk=; b=KiQ3ebxUegYFmy/p/E2B7YZDXh qwN4Y2+eMrlFnc4DBn6DBN4rmksuzVeKrH6mulW48AH1fMvwCeEs2uEGHqAKGr2t IbYHRPgKy+cU38l9ZTZF44v5G3ZdPSzepUjTdRg6rAJ2nUp5qscaZ1bE5MwSfYtV 7MyZBGmB2N6YC2QAHgkeaZyKl5zmU1ocdfU3CIJGRAAJ8WS9xLEShPXgkJD+zV1j FMCZsx/ajbck1rubqSllOUrSe2i1SX+JBsOdq724HGCkmE1NfWgHlU8+M0n7fVI0 oPQrMZxZVIPWHZEMqYx0ozL5ZB7G0S/bT9GP+WcYq98q6/GkDoVm6RArqBcg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1729770384; x=1729856784; bh=MTRkXvw6t0FSqOMZZJW27DpDqfh6 nWVWSPW17/JpGEk=; b=I5WyukWAFg+Ld9I0q6B2GkmuxGpY7rPsO/DoyHULfKtW H/m3bqYVGkafbKS6+8ZZJQF9LDoDGHPIjfDGZx2jEnzzEbZg4NznkQZMA5sSmvYX Jyp8eaojo4qQpgeiwBObn6Y+hiZIax+HdvMGuQD2Y0P8aW6qAFrT8UJcUpWtRa1l YQGodLiNoe3AtFif39Oe5yLkfrWC08GnhgA2DWNcDCbJpgsQEwke2x8Zb0aQcx5g SueGA5x7cYBNG/ilmV9jDSE5MKKEHWYx/zj3sEvxP9xO4jFFABrbTRsmpyE7ChYl nJ3khsN5CrMeKI1/3OmreO43H5YPFVGSaTLNs+OWvg== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeftddrvdejtddgudekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggvpdfu rfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnh htshculddquddttddmnecujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvden ucfhrhhomheprfgrthhrihgtkhcuufhtvghinhhhrghrughtuceophhssehpkhhsrdhimh eqnecuggftrfgrthhtvghrnhepveekkeffhfeitdeludeigfejtdetvdelvdduhefgueeg udfghfeukefhjedvkedtnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrg hilhhfrhhomhepphhssehpkhhsrdhimhdpnhgspghrtghpthhtohepgedpmhhouggvpehs mhhtphhouhhtpdhrtghpthhtohepghhithesvhhgvghrrdhkvghrnhgvlhdrohhrghdprh gtphhtthhopehmvgesthhtrgihlhhorhhrrdgtohhmpdhrtghpthhtohepkhhrihhsthho fhhfvghrhhgruhhgshgsrghkkhesfhgrshhtmhgrihhlrdgtohhmpdhrtghpthhtohepjh hohhgrnhhnvghsrdhstghhihhnuggvlhhinhesghhmgidruggv X-ME-Proxy: Feedback-ID: i197146af:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 24 Oct 2024 07:46:23 -0400 (EDT) Received: by vm-mail (OpenSMTPD) with ESMTPSA id fd86691b (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Thu, 24 Oct 2024 11:46:26 +0000 (UTC) Date: Thu, 24 Oct 2024 13:46:20 +0200 From: Patrick Steinhardt To: git@vger.kernel.org Cc: Johannes Schindelin , Taylor Blau , Kristoffer Haugsbakk Subject: [PATCH v2 1/3] compat/mingw: share file handles created via `CreateFileW()` Message-ID: <63c2cfa87a4a3c44367acdc1f7cdb57289b4b761.1729770140.git.ps@pks.im> References: Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Unless told otherwise, Windows will keep other processes from reading, writing and deleting files when one has an open handle that was created via `CreateFileW()`. This behaviour can be altered via `FILE_SHARE_*` flags: - `FILE_SHARE_READ` allows a concurrent process to open the file for reading. - `FILE_SHARE_WRITE` allows a concurrent process to open the file for writing. - `FILE_SHARE_DELETE` allows a concurrent process to delete the file or to replace it via an atomic rename. This sharing mechanism is quite important in the context of Git, as we assume POSIX semantics all over the place. But there are two callsites where we don't pass all three of these flags: - We don't set `FILE_SHARE_DELETE` when creating a file for appending via `mingw_open_append()`. This makes it impossible to delete the file from another process or to replace it via an atomic rename. The function was introduced via d641097589 (mingw: enable atomic O_APPEND, 2018-08-13) and has been using `FILE_SHARE_READ | FILE_SHARE_WRITE` since the inception. There aren't any indicators that the omission of `FILE_SHARE_DELETE` was intentional. - We don't set any sharing flags in `mingw_utime()`, which changes the access and modification of a file. This makes it impossible to perform any kind of operation on this file at all from another process. While we only open the file for a short amount of time to update its timestamps, this still opens us up for a race condition with another process. `mingw_utime()` was originally implemented via `_wopen()`, which doesn't give you full control over the sharing mode. Instead, it calls `_wsopen()` with `_SH_DENYNO`, which ultimately translates to `FILE_SHARE_READ | FILE_SHARE_WRITE`. It was then refactored via 090a3085bc (t/helper/test-chmtime: update mingw to support chmtime on directories, 2022-03-02) to use `CreateFileW()`, but we stopped setting any sharing flags at all, which seems like an unintentional side effect. By restoring `FILE_SHARE_READ | FILE_SHARE_WRITE` we thus fix this and get back the old behaviour of `_wopen()`. The fact that we didn't set the equivalent of `FILE_SHARE_DELETE` can be explained, as well: neither `_wopen()` nor `_wsopen()` allow you to do so. So overall, it doesn't seem intentional that we didn't allow deletions here, either. Adapt both of these callsites to pass all three sharing flags. Signed-off-by: Patrick Steinhardt --- compat/mingw.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/compat/mingw.c b/compat/mingw.c index 0e851ecae29..e326c6fcd2d 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -502,7 +502,7 @@ static int mingw_open_append(wchar_t const *wfilename, int oflags, ...) * to append to the file. */ handle = CreateFileW(wfilename, FILE_APPEND_DATA, - FILE_SHARE_WRITE | FILE_SHARE_READ, + FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE, NULL, create, FILE_ATTRIBUTE_NORMAL, NULL); if (handle == INVALID_HANDLE_VALUE) { DWORD err = GetLastError(); @@ -1006,7 +1006,7 @@ int mingw_utime (const char *file_name, const struct utimbuf *times) osfilehandle = CreateFileW(wfilename, FILE_WRITE_ATTRIBUTES, - 0 /*FileShare.None*/, + FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING, (attrs != INVALID_FILE_ATTRIBUTES && From patchwork Thu Oct 24 11:46:23 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Steinhardt X-Patchwork-Id: 13848831 Received: from fhigh-a3-smtp.messagingengine.com (fhigh-a3-smtp.messagingengine.com [103.168.172.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3E424170853 for ; Thu, 24 Oct 2024 11:46:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.154 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770390; cv=none; b=jhVHziJiYnyDFt1AD/NrQO9IDBPsrw8wPAOqjipnDw2RSn18WiHU8ejOeuTgTQx6exsdpirP0IZwrO6JPdAmaVGfKsv4D6WKCzd9fpWZUexR2TL4ytAIBol4lWXGnQr+DBELUJnU5YPooWx522JmCW72yKMGeNAVJJ+R6jTrvDE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770390; c=relaxed/simple; bh=ieqZX9cixRkKreNQS5LSlKhSy0wtaD7nT+ENiWSqX1I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J5LAb7zT0IhIY+wXSAdi6qyQKDs0oRNt1U4CdHLIMWWcKSkok7n33Cd90DKEyZTizyaurvCOYJK/yrQ+Zt+mr6MJq2SKz7lv5oajighBNeOQz4m0BU3Flrlmuccz5KTkuAexS6+rGM4EszgP3HP1jhbGsq1wHyUmWvJULSRoqq8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=pks.im; spf=pass smtp.mailfrom=pks.im; dkim=pass (2048-bit key) header.d=pks.im header.i=@pks.im header.b=zPQq543N; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=ncKNeUba; arc=none smtp.client-ip=103.168.172.154 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=pks.im Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pks.im Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pks.im header.i=@pks.im header.b="zPQq543N"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="ncKNeUba" Received: from phl-compute-01.internal (phl-compute-01.phl.internal [10.202.2.41]) by mailfhigh.phl.internal (Postfix) with ESMTP id 4F7E6114017D; Thu, 24 Oct 2024 07:46:27 -0400 (EDT) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-01.internal (MEProxy); Thu, 24 Oct 2024 07:46:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pks.im; h=cc:cc :content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:subject :subject:to:to; s=fm3; t=1729770387; x=1729856787; bh=D9lvrtj2Po /MIjLzuFkdAv7rGKqis51gfkHfcbOwbdE=; b=zPQq543NvCEPoJhAJOY05wT1jF fTt+KMxBSZuRwYrQNTBrK3woYPTspp26csCXeiRrnJBXPhzEOhmhCuatuS3VDzgb a7IejgFPu22mtsbZzUayzj7ynnxIPZvZozH6S8Dc/s81fRWxcn9GJ+8i5d7AWioc suPSw9zon9CP1rthRFNbaNGv1z4gCE0wqNSBah/WYrBYpHIDWnGaYfBuZhi5NbnG aQ4B/NDCPEjkAot95191cxhDu53Cj3MqLL9iH91A+icKwDSZHZr+vW3DSbFrxjfC mQYLoPmd2baKHXaocM4FYfyt019IMkM1VDyOo6/b1N/CHmatNVk+0zALeImg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1729770387; x=1729856787; bh=D9lvrtj2Po/MIjLzuFkdAv7rGKqi s51gfkHfcbOwbdE=; b=ncKNeUbaDUriTC4B64NllLcgaOBq0lBWrXUBNVtfF+zz nrSrg6ohecLze02tV9vqkXUDc8BxoJcCUfQ7O5xDNafFxB4q3mkRoVIpupYKkQ6R ihud3yqReRVhcplLoObygKqcSa9OwTt7L/wCpinhNlnW20IQHEDa5av5VjlwL96c 97ZE/6jRN5TR4BLseA4XEJhtJYjGuY8JLgU2hPUeO9nK0vAfT1J3RMnX8bb2h9IX 5inDx17jpazd5BCultCjljfzbQsw5cGwYRYi2T0YnfS/uGjQv2YtfcvjIb9o99Jf 1DZBpWKsSQkemKK+sjJC3s0GbZ/SX0Fy72L5EOgcZQ== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeftddrvdejtddgudelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggvpdfu rfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnh htshculddquddttddmnecujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvden ucfhrhhomheprfgrthhrihgtkhcuufhtvghinhhhrghrughtuceophhssehpkhhsrdhimh eqnecuggftrfgrthhtvghrnhepveekkeffhfeitdeludeigfejtdetvdelvdduhefgueeg udfghfeukefhjedvkedtnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrg hilhhfrhhomhepphhssehpkhhsrdhimhdpnhgspghrtghpthhtohepgedpmhhouggvpehs mhhtphhouhhtpdhrtghpthhtohepghhithesvhhgvghrrdhkvghrnhgvlhdrohhrghdprh gtphhtthhopehjohhhrghnnhgvshdrshgthhhinhguvghlihhnsehgmhigrdguvgdprhgt phhtthhopehmvgesthhtrgihlhhorhhrrdgtohhmpdhrtghpthhtohepkhhrihhsthhofh hfvghrhhgruhhgshgsrghkkhesfhgrshhtmhgrihhlrdgtohhm X-ME-Proxy: Feedback-ID: i197146af:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 24 Oct 2024 07:46:26 -0400 (EDT) Received: by vm-mail (OpenSMTPD) with ESMTPSA id 15ab1f42 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Thu, 24 Oct 2024 11:46:29 +0000 (UTC) Date: Thu, 24 Oct 2024 13:46:23 +0200 From: Patrick Steinhardt To: git@vger.kernel.org Cc: Johannes Schindelin , Taylor Blau , Kristoffer Haugsbakk Subject: [PATCH v2 2/3] compat/mingw: allow deletion of most opened files Message-ID: References: Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: On Windows, we emulate open(3p) via `mingw_open()`. This function implements handling of some platform-specific quirks that are required to make it behave as closely as possible like open(3p) would, but for most cases we just call the Windows-specific `_wopen()` function. This function has a major downside though: it does not allow us to specify the sharing mode. While there is `_wsopen()` that allows us to pass sharing flags, those sharing flags are not the same `FILE_SHARE_*` flags as `CreateFileW()` accepts. Instead, `_wsopen()` only allows concurrent read- and write-access, but does not allow for concurrent deletions. Unfortunately though, we have to allow concurrent deletions if we want to have POSIX-style atomic renames on top of an existing file that has open file handles. Implement a new function that emulates open(3p) for existing files via `CreateFileW()` such that we can set the required sharing flags. While we have the same issue when calling open(3p) with `O_CREAT`, implementing that mode would be more complex due to the required permission handling. Furthermore, atomic updates via renames typically write to exclusive lockfile and then perform the rename, and thus we don't have to handle the case where the locked path has been created with `O_CREATE`. So while it would be nice to have proper POSIX semantics in all paths, we instead aim for a minimum viable fix here. Signed-off-by: Patrick Steinhardt --- compat/mingw.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) diff --git a/compat/mingw.c b/compat/mingw.c index e326c6fcd2d..6c75fe36b15 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -532,6 +532,62 @@ static int mingw_open_append(wchar_t const *wfilename, int oflags, ...) return fd; } +/* + * Ideally, we'd use `_wopen()` to implement this functionality so that we + * don't have to reimplement it, but unfortunately we do not have tight control + * over the share mode there. And while `_wsopen()` and friends exist that give + * us _some_ control over the share mode, this family of functions doesn't give + * us the ability to enable FILE_SHARE_DELETE, either. But this is a strict + * requirement for us though so that we can unlink or rename over files that + * are held open by another process. + * + * We are thus forced to implement our own emulation of `open()`. To make our + * life simpler we only implement basic support for this, namely opening + * existing files for reading and/or writing. This means that newly created + * files won't have their sharing mode set up correctly, but for now I couldn't + * find any case where this matters. We may have to revisit that in the future + * though based on our needs. + */ +static int mingw_open_existing(const wchar_t *filename, int oflags, ...) +{ + SECURITY_ATTRIBUTES security_attributes = { + .nLength = sizeof(security_attributes), + .bInheritHandle = !(oflags & O_NOINHERIT), + }; + HANDLE handle; + int access; + int fd; + + /* We only support basic flags. */ + if (oflags & ~(O_ACCMODE | O_NOINHERIT)) { + errno = ENOSYS; + return -1; + } + + if (oflags & O_RDWR) + access = GENERIC_READ | GENERIC_WRITE; + else if (oflags & O_WRONLY) + access = GENERIC_WRITE; + else + access = GENERIC_READ; + + handle = CreateFileW(filename, access, + FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE, + &security_attributes, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); + if (handle == INVALID_HANDLE_VALUE) { + DWORD err = GetLastError(); + if (err == ERROR_INVALID_PARAMETER) + err = ERROR_PATH_NOT_FOUND; + errno = err_win_to_posix(err); + return -1; + } + + fd = _open_osfhandle((intptr_t)handle, oflags | O_BINARY); + if (fd < 0) + CloseHandle(handle); + return fd; +} + /* * Does the pathname map to the local named pipe filesystem? * That is, does it have a "//./pipe/" prefix? @@ -567,6 +623,8 @@ int mingw_open (const char *filename, int oflags, ...) if ((oflags & O_APPEND) && !is_local_named_pipe_path(filename)) open_fn = mingw_open_append; + else if (!(oflags & ~(O_ACCMODE | O_NOINHERIT))) + open_fn = mingw_open_existing; else open_fn = _wopen; From patchwork Thu Oct 24 11:46:26 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Steinhardt X-Patchwork-Id: 13848832 Received: from fhigh-a3-smtp.messagingengine.com (fhigh-a3-smtp.messagingengine.com [103.168.172.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C692E1D041D for ; Thu, 24 Oct 2024 11:46:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.154 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770396; cv=none; b=C36kpW+bd/6py4QeivWEq+Up9k8jiFLlFmldBb7ExFOjq52kCBilbV5qO3XXQvq7NrtVP+kmmRmlIusbMGpZ3GIG0icgGFYX4SGO7PKo49YFggfq6fbRnzmGVrfQT3K/pkgbsKwP55VA6pjqxPsv7Rog/3vVulmED+7C1pi4O+8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729770396; c=relaxed/simple; bh=Zg0Zx3iHMWU3tSKhHL925MV8XsPECiDeHDgfAiUFzME=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=eZXdS6brk51Sr74Q/VQ8h8jy+4HqLoGPloRiyiAuRCcBNAZPEIKfer3EikDUFko7U5zRy6mduoNx/FnLrg4ojj73EEqbRuPS5TlahsHR7U8hLiqBSd5EmFAzDPaRb6VXHYtJu9du5zwuKdqjdtVobgrlOPinFmpQ4yoHwvHwg7Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=pks.im; spf=pass smtp.mailfrom=pks.im; dkim=pass (2048-bit key) header.d=pks.im header.i=@pks.im header.b=SyygtjKS; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=beS9w+Sl; arc=none smtp.client-ip=103.168.172.154 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=pks.im Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pks.im Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pks.im header.i=@pks.im header.b="SyygtjKS"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="beS9w+Sl" Received: from phl-compute-05.internal (phl-compute-05.phl.internal [10.202.2.45]) by mailfhigh.phl.internal (Postfix) with ESMTP id A341C11400FC; Thu, 24 Oct 2024 07:46:32 -0400 (EDT) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-05.internal (MEProxy); Thu, 24 Oct 2024 07:46:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pks.im; h=cc:cc :content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:subject :subject:to:to; s=fm3; t=1729770392; x=1729856792; bh=jKlUbthhLb vGbzMQesf1U36tzXINICflZOhFIFljN6k=; b=SyygtjKSBeacBDhHgjYFqQ7j03 Ki0vusscuDjq6R/CENqiZ8sp62HqLbydMQElUycLaq1N0w/V9SgSoigQbtkzRBeX LDk5f41iJYqYqw8SiVtelnRNK0YxjczG2p+nS6jOFkI73clcA0BL4lXHXg1Ml0mD MIzoHVwwr+xooLUwALrn6qVvE8cn+YwQHl93Hia/O4gYo1YuAvrsoftbi7UwjUel ijK2cuVPsctIRiJwjAhstPFDwEmikNkT36f8G/UMBXDo+efbBrfdzHCUwPCgc3jj XNzt5utj1xHwG8gjAxMg5zLYBg3wOFJBkQU7xa3ZkXzK16V+ZrO+GCEgfEBA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1729770392; x=1729856792; bh=jKlUbthhLbvGbzMQesf1U36tzXIN ICflZOhFIFljN6k=; b=beS9w+SlwiGVq33pClMxHIxSESvsPuOeteauH8S+tggm ZmwvgXstwusG5lrOP7BaeUczhgG3v7CtX9QBUsCAdwHI9WFE8U1XOT+3A15oolpJ 2ZVTJv3KZIcE6LdOxhLoRX6GJIviQ5Nw0+QFKlsWVXiEfgJdvvDpcoE/fwBwsLZZ 00Fxr6EyJMDpBJYqdtFIGc7QuvYxFV3uW6a6k8COF3VXyLL1045pOmSNpbKOB1o1 cN+/PyGMfPsvF0xSO1I4rjg+evN03Z6AW2YYSTnV/FcZ2pzthOfGJ3u0gG1cbpP5 qB3VqqO2an5HHyYvV3I3E2ODV97CiJSSGHDKEjldgw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeftddrvdejtddgudekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggvpdfu rfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnh htshculddquddttddmnecujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvden ucfhrhhomheprfgrthhrihgtkhcuufhtvghinhhhrghrughtuceophhssehpkhhsrdhimh eqnecuggftrfgrthhtvghrnhepjeehffduffeufeeludelleeivedvffeludeuheeuuddt udelgfetgeffffdukeegnecuffhomhgrihhnpehmihgtrhhoshhofhhtrdgtohhmnecuve hluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepphhssehpkhhs rdhimhdpnhgspghrtghpthhtohepgedpmhhouggvpehsmhhtphhouhhtpdhrtghpthhtoh epghhithesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehjohhhrghnnhgv shdrshgthhhinhguvghlihhnsehgmhigrdguvgdprhgtphhtthhopehkrhhishhtohhffh gvrhhhrghughhssggrkhhksehfrghsthhmrghilhdrtghomhdprhgtphhtthhopehmvges thhtrgihlhhorhhrrdgtohhm X-ME-Proxy: Feedback-ID: i197146af:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 24 Oct 2024 07:46:31 -0400 (EDT) Received: by vm-mail (OpenSMTPD) with ESMTPSA id 5755527e (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Thu, 24 Oct 2024 11:46:34 +0000 (UTC) Date: Thu, 24 Oct 2024 13:46:26 +0200 From: Patrick Steinhardt To: git@vger.kernel.org Cc: Johannes Schindelin , Taylor Blau , Kristoffer Haugsbakk Subject: [PATCH v2 3/3] compat/mingw: support POSIX semantics for atomic renames Message-ID: References: Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: By default, Windows restricts access to files when those files have been opened by another process. As explained in the preceding commits, these restrictions can be loosened such that reads, writes and/or deletes of files with open handles _are_ allowed. While we set up those sharing flags in most relevant code paths now, we still don't properly handle POSIX-style atomic renames in case the target path is open. This is failure demonstrated by t0610, where one of our tests spawns concurrent writes in a reftable-enabled repository and expects all of them to succeed. This test fails most of the time because the process that has acquired the "tables.list" lock is unable to rename it into place while other processes are busy reading that file. Windows 10 has introduced the `FILE_RENAME_FLAG_POSIX_SEMANTICS` flag that allows us to fix this usecase [1]. When set, it is possible to rename a file over a preexisting file even when the target file still has handles open. Those handles must have been opened with the `FILE_SHARE_DELETE` flag, which we have ensured in the preceding commits. Careful readers might have noticed that [1] does not mention the above flag, but instead mentions `FILE_RENAME_POSIX_SEMANTICS`. This flag is not for use with `SetFileInformationByHandle()` though, which is what we use. And while the `FILE_RENAME_FLAG_POSIX_SEMANTICS` flag exists, it is not documented on [2] or anywhere else as far as I can tell. Unfortunately, we still support Windows systems older than Windows 10 that do not yet have this new flag. Our `_WIN32_WINNT` SDK version still targets 0x0600, which is Windows Vista and later. And even though that Windows version is out-of-support, bumping the SDK version all the way to 0x0A00, which is Windows 10 and later, is not an option as it would make it impossible to compile on Windows 8.1, which is still supported. Instead, we have to manually declare the relevant infrastructure to make this feature available and have fallback logic in place in case we run on a Windows version that does not yet have this flag. On another note: `mingw_rename()` has a retry loop that is used in case deleting a file failed because it's still open in another process. One might be pressed to not use this loop anymore when we can use POSIX semantics. But unfortunately, we have to keep it around due to our dependence on the `FILE_SHARE_DELETE` flag. While we know to set that sharing flag now, other applications may not do so and may thus still cause sharing violations when we try to rename a file. This fixes concurrent writes in the reftable backend as demonstrated in t0610, but may also end up fixing other usecases where Git wants to perform renames. [1]: https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntifs/ns-ntifs-_file_rename_information [2]: https://learn.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-file_rename_info Signed-off-by: Patrick Steinhardt --- compat/mingw.c | 87 ++++++++++++++++++++++++++++++++++++-- t/t0610-reftable-basics.sh | 8 ++-- 2 files changed, 88 insertions(+), 7 deletions(-) diff --git a/compat/mingw.c b/compat/mingw.c index 6c75fe36b15..22c005a4533 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -2209,10 +2209,16 @@ int mingw_accept(int sockfd1, struct sockaddr *sa, socklen_t *sz) #undef rename int mingw_rename(const char *pold, const char *pnew) { + static int supports_file_rename_info_ex = 1; DWORD attrs, gle; int tries = 0; wchar_t wpold[MAX_PATH], wpnew[MAX_PATH]; - if (xutftowcs_path(wpold, pold) < 0 || xutftowcs_path(wpnew, pnew) < 0) + int wpnew_len; + + if (xutftowcs_path(wpold, pold) < 0) + return -1; + wpnew_len = xutftowcs_path(wpnew, pnew); + if (wpnew_len < 0) return -1; /* @@ -2223,11 +2229,84 @@ int mingw_rename(const char *pold, const char *pnew) return 0; if (errno != EEXIST) return -1; + repeat: - if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING)) - return 0; + if (supports_file_rename_info_ex) { + /* + * Our minimum required Windows version is still set to Windows + * Vista. We thus have to declare required infrastructure for + * FileRenameInfoEx ourselves until we bump _WIN32_WINNT to + * 0x0A00. Furthermore, we have to handle cases where the + * FileRenameInfoEx call isn't supported yet. + */ +#define FILE_RENAME_FLAG_REPLACE_IF_EXISTS 0x00000001 +#define FILE_RENAME_FLAG_POSIX_SEMANTICS 0x00000002 + FILE_INFO_BY_HANDLE_CLASS FileRenameInfoEx = 22; + struct { + /* + * This is usually an unnamed union, but that is not + * part of ISO C99. We thus inline the field, as we + * really only care for the Flags field anyway. + */ + DWORD Flags; + HANDLE RootDirectory; + DWORD FileNameLength; + /* + * The actual structure is defined with a single-character + * flex array so that the structure has to be allocated on + * the heap. As we declare this structure ourselves though + * we can avoid the allocation and define FileName to have + * MAX_PATH bytes. + */ + WCHAR FileName[MAX_PATH]; + } rename_info = { 0 }; + HANDLE old_handle = INVALID_HANDLE_VALUE; + BOOL success; + + old_handle = CreateFileW(wpold, DELETE, + FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE, + NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); + if (old_handle == INVALID_HANDLE_VALUE) { + errno = err_win_to_posix(GetLastError()); + return -1; + } + + rename_info.Flags = FILE_RENAME_FLAG_REPLACE_IF_EXISTS | + FILE_RENAME_FLAG_POSIX_SEMANTICS; + rename_info.FileNameLength = wpnew_len * sizeof(WCHAR); + memcpy(rename_info.FileName, wpnew, wpnew_len * sizeof(WCHAR)); + + success = SetFileInformationByHandle(old_handle, FileRenameInfoEx, + &rename_info, sizeof(rename_info)); + gle = GetLastError(); + CloseHandle(old_handle); + if (success) + return 0; + + /* + * When we see ERROR_INVALID_PARAMETER we can assume that the + * current system doesn't support FileRenameInfoEx. Keep us + * from using it in future calls and retry. + */ + if (gle == ERROR_INVALID_PARAMETER) { + supports_file_rename_info_ex = 0; + goto repeat; + } + + /* + * In theory, we shouldn't get ERROR_ACCESS_DENIED because we + * always open files with FILE_SHARE_DELETE But in practice we + * cannot assume that Git is the only one accessing files, and + * other applications may not set FILE_SHARE_DELETE. So we have + * to retry. + */ + } else { + if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING)) + return 0; + gle = GetLastError(); + } + /* TODO: translate more errors */ - gle = GetLastError(); if (gle == ERROR_ACCESS_DENIED && (attrs = GetFileAttributesW(wpnew)) != INVALID_FILE_ATTRIBUTES) { if (attrs & FILE_ATTRIBUTE_DIRECTORY) { diff --git a/t/t0610-reftable-basics.sh b/t/t0610-reftable-basics.sh index babec7993e3..eaf6fab6d29 100755 --- a/t/t0610-reftable-basics.sh +++ b/t/t0610-reftable-basics.sh @@ -450,10 +450,12 @@ test_expect_success 'ref transaction: retry acquiring tables.list lock' ' ) ' -# This test fails most of the time on Windows systems. The root cause is +# This test fails most of the time on Cygwin systems. The root cause is # that Windows does not allow us to rename the "tables.list.lock" file into -# place when "tables.list" is open for reading by a concurrent process. -test_expect_success !WINDOWS 'ref transaction: many concurrent writers' ' +# place when "tables.list" is open for reading by a concurrent process. We have +# worked around that in our MinGW-based rename emulation, but the Cygwin +# emulation seems to be insufficient. +test_expect_success !CYGWIN 'ref transaction: many concurrent writers' ' test_when_finished "rm -rf repo" && git init repo && (