From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 483DD65321 for ; Wed, 22 Jul 2020 15:57:07 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 2AE90210BF for ; Wed, 22 Jul 2020 15:56:38 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [212.186.127.180]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 7FC5D210A9 for ; Wed, 22 Jul 2020 15:56:35 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 49FAF431A8 for ; Wed, 22 Jul 2020 15:56:35 +0200 (CEST) From: Stefan Reiter To: pbs-devel@lists.proxmox.com Date: Wed, 22 Jul 2020 15:56:25 +0200 Message-Id: <20200722135625.23653-6-s.reiter@proxmox.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200722135625.23653-1-s.reiter@proxmox.com> References: <20200722135625.23653-1-s.reiter@proxmox.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.015 Adjusted score from AWL reputation of From: address KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment RCVD_IN_DNSWL_MED -2.3 Sender listed at https://www.dnswl.org/, medium trust SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [restore.rs, lib.rs] Subject: [pbs-devel] [PATCH v2 backup-qemu 5/5] read_image_at: iterate until buffer is filled X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Jul 2020 13:57:07 -0000 QEMU will always assume EOF when less bytes than requested are returned by a block drivers 'read' interface, so we need to fill the buffer up to 'size' if possible. Signed-off-by: Stefan Reiter --- v2 note: this was previously a QEMU patch, but honestly that's stupid so let's do it in Rust instead. current-api.h | 4 ++-- src/lib.rs | 4 ++-- src/restore.rs | 20 ++++++++++++++++---- 3 files changed, 20 insertions(+), 8 deletions(-) diff --git a/current-api.h b/current-api.h index 15bb275..d77eff6 100644 --- a/current-api.h +++ b/current-api.h @@ -364,8 +364,8 @@ int proxmox_restore_read_image_at(ProxmoxRestoreHandle *handle, * Note: The data pointer needs to be valid until the async * opteration is finished. * - * Note: It is not an error for a successful call to transfer fewer - * bytes than requested. + * Note: The call will only ever transfer less than 'size' bytes if + * the end of the file has been reached. */ void proxmox_restore_read_image_at_async(ProxmoxRestoreHandle *handle, uint8_t aid, diff --git a/src/lib.rs b/src/lib.rs index d4b9370..3346be8 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -934,8 +934,8 @@ pub extern "C" fn proxmox_restore_read_image_at( /// Note: The data pointer needs to be valid until the async /// opteration is finished. /// -/// Note: It is not an error for a successful call to transfer fewer -/// bytes than requested. +/// Note: The call will only ever transfer less than 'size' bytes if +/// the end of the file has been reached. #[no_mangle] #[allow(clippy::not_unsafe_ptr_arg_deref)] pub extern "C" fn proxmox_restore_read_image_at_async( diff --git a/src/restore.rs b/src/restore.rs index 2be0295..e43d040 100644 --- a/src/restore.rs +++ b/src/restore.rs @@ -262,10 +262,22 @@ impl RestoreTask { } let mut reader = reader.lock().await; - reader.seek(SeekFrom::Start(offset)).await?; - let buf: &mut [u8] = unsafe { std::slice::from_raw_parts_mut(data.0 as *mut u8, size as usize)}; - let bytes = reader.read(buf).await?; - Ok(bytes.try_into()?) + let buf: &mut [u8] = unsafe { std::slice::from_raw_parts_mut(data.0 as *mut u8, size as usize)}; + let mut read = 0; + + while read < size { + reader.seek(SeekFrom::Start(offset + read)).await?; + let bytes = reader.read(&mut buf[read as usize..]).await?; + + if bytes == 0 { + // EOF + break; + } + + read += bytes as u64; + } + + Ok(read.try_into()?) } } -- 2.20.1