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[149.14.88.106]) by smtp.gmail.com with ESMTPSA id m34-20020a05600c3b2200b00380e3225af9sm11392948wms.0.2022.02.28.05.36.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Feb 2022 05:36:31 -0800 (PST) Message-ID: <493ea7b6-4e62-5c6e-682b-d5a787ae9299@redhat.com> Date: Mon, 28 Feb 2022 14:36:30 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v9 09/11] 9p: darwin: Implement compatibility for mknodat To: Christian Schoenebeck , qemu-devel@nongnu.org References: <20220227223522.91937-1-wwcohen@gmail.com> <20220227223522.91937-10-wwcohen@gmail.com> <5277572.8N0aQqchxN@silver> From: Thomas Huth In-Reply-To: <5277572.8N0aQqchxN@silver> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: , Cc: Laurent Vivier , Greg Kurz , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , hi@alyssa.is, Michael Roitzsch , Will Cohen , Paolo Bonzini , Keno Fischer Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 28/02/2022 14.20, Christian Schoenebeck wrote: > On Sonntag, 27. Februar 2022 23:35:20 CET Will Cohen wrote: >> From: Keno Fischer >> >> Darwin does not support mknodat. However, to avoid race conditions >> with later setting the permissions, we must avoid using mknod on >> the full path instead. We could try to fchdir, but that would cause >> problems if multiple threads try to call mknodat at the same time. >> However, luckily there is a solution: Darwin includes a function >> that sets the cwd for the current thread only. >> This should suffice to use mknod safely. >> >> This function (pthread_fchdir_np) is protected by a check in >> meson in a patch later in this series. >> >> Signed-off-by: Keno Fischer >> Signed-off-by: Michael Roitzsch >> [Will Cohen: - Adjust coding style >> - Replace clang references with gcc >> - Note radar filed with Apple for missing syscall >> - Replace direct syscall with pthread_fchdir_np and >> adjust patch notes accordingly >> - Declare pthread_fchdir_np with >> - __attribute__((weak_import)) to allow checking for >> its presence before usage >> - Move declarations above cplusplus guard >> - Add CONFIG_PTHREAD_FCHDIR_NP to meson and check for >> presence in 9p-util >> - Rebase to apply cleanly on top of the 2022-02-10 >> changes to 9pfs >> - Fix line over 90 characters formatting error] >> Signed-off-by: Will Cohen >> --- >> hw/9pfs/9p-local.c | 4 ++-- >> hw/9pfs/9p-util-darwin.c | 33 +++++++++++++++++++++++++++++++++ >> hw/9pfs/9p-util-linux.c | 6 ++++++ >> hw/9pfs/9p-util.h | 11 +++++++++++ >> meson.build | 1 + >> 5 files changed, 53 insertions(+), 2 deletions(-) >> >> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c >> index a0d08e5216..d42ce6d8b8 100644 >> --- a/hw/9pfs/9p-local.c >> +++ b/hw/9pfs/9p-local.c >> @@ -682,7 +682,7 @@ static int local_mknod(FsContext *fs_ctx, V9fsPath >> *dir_path, >> >> if (fs_ctx->export_flags & V9FS_SM_MAPPED || >> fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) { >> - err = mknodat(dirfd, name, fs_ctx->fmode | S_IFREG, 0); >> + err = qemu_mknodat(dirfd, name, fs_ctx->fmode | S_IFREG, 0); >> if (err == -1) { >> goto out; >> } >> @@ -697,7 +697,7 @@ static int local_mknod(FsContext *fs_ctx, V9fsPath >> *dir_path, } >> } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH || >> fs_ctx->export_flags & V9FS_SM_NONE) { >> - err = mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev); >> + err = qemu_mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev); >> if (err == -1) { >> goto out; >> } >> diff --git a/hw/9pfs/9p-util-darwin.c b/hw/9pfs/9p-util-darwin.c >> index cdb4c9e24c..bec0253474 100644 >> --- a/hw/9pfs/9p-util-darwin.c >> +++ b/hw/9pfs/9p-util-darwin.c >> @@ -7,6 +7,8 @@ >> >> #include "qemu/osdep.h" >> #include "qemu/xattr.h" >> +#include "qapi/error.h" >> +#include "qemu/error-report.h" >> #include "9p-util.h" >> >> ssize_t fgetxattrat_nofollow(int dirfd, const char *filename, const char >> *name, @@ -62,3 +64,34 @@ int fsetxattrat_nofollow(int dirfd, const char >> *filename, const char *name, close_preserve_errno(fd); >> return ret; >> } >> + >> +/* >> + * As long as mknodat is not available on macOS, this workaround >> + * using pthread_fchdir_np is needed. >> + * >> + * Radar filed with Apple for implementing mknodat: >> + * rdar://FB9862426 (https://openradar.appspot.com/FB9862426) >> + */ >> +#if defined CONFIG_PTHREAD_FCHDIR_NP >> + >> +int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev) >> +{ >> + int preserved_errno, err; >> + if (!pthread_fchdir_np) { >> + error_report_once("pthread_fchdir_np() not available on this version of macOS"); > > You took the code style error message a bit too literal; this line is still > too long: > > WARNING: line over 80 characters > #199: FILE: hw/9pfs/9p-util-darwin.c:81: > + error_report_once("pthread_fchdir_np() not available on this version of macOS"); > > total: 0 errors, 1 warnings, 91 lines checked > > However this is too trivial to send a v10 just for this. If there are no other > issues in this v9 then I'll simply fix this on my end. My plan is to queue > this series tomorrow. For lines less than 90 characters, it's just a warning, and I think it's ok in such cases to keep it longer than 80 characters, if the result of breaking it up would look more awkward otherwise. Thomas