From patchwork Sun Oct 9 19:50:02 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Juan Quintela X-Patchwork-Id: 118622 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [140.186.70.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 1CF67B6F9D for ; Mon, 10 Oct 2011 07:04:28 +1100 (EST) Received: from localhost ([::1]:51251 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RCzbl-0005Td-CG for incoming@patchwork.ozlabs.org; Sun, 09 Oct 2011 16:04:25 -0400 Received: from eggs.gnu.org ([140.186.70.92]:47633) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RCzbf-0005TM-DD for qemu-devel@nongnu.org; Sun, 09 Oct 2011 16:04:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RCzbe-0007F0-Ai for qemu-devel@nongnu.org; Sun, 09 Oct 2011 16:04:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58191) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RCzPf-0004mU-Hp for qemu-devel@nongnu.org; Sun, 09 Oct 2011 15:51:56 -0400 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p99JprWu022972 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sun, 9 Oct 2011 15:51:53 -0400 Received: from neno.neno (ovpn-116-17.ams2.redhat.com [10.36.116.17]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id p99Jorop007860; Sun, 9 Oct 2011 15:51:47 -0400 From: Juan Quintela To: qemu-devel@nongnu.org Date: Sun, 9 Oct 2011 21:50:02 +0200 Message-Id: <4cb62cf10320417d6cf9c74f60503b8a186fc0cc.1318189536.git.quintela@redhat.com> In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 4/5] savevm: improve subsections detection on load X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org We add qemu_peek_buffer, that is identical to qemu_get_buffer, just that it don't update f->buf_index. We add a paramenter to qemu_peek_byte() to be able to peek more than one byte. Once this is done, to see if we have a subsection we look: - 1st byte is QEMU_VM_SUBSECTION - 2nd byte is a length, and is bigger than section name - 3rd element is a string that starts with section_name So, we shouldn't have false positives (yes, content could still get us wrong but probabilities are really low). v2: - Alex Williamsom found that we could get negative values on index. - Rework code to fix that part. - Rewrite qemu_get_buffer() using qemu_peek_buffer() v3: - return "done" on error case v4: - fix qemu_file_skip() off by one. Signed-off-by: Juan Quintela --- savevm.c | 110 ++++++++++++++++++++++++++++++++++++++++++-------------------- 1 files changed, 75 insertions(+), 35 deletions(-) diff --git a/savevm.c b/savevm.c index 94628c6..ad58e7c 100644 --- a/savevm.c +++ b/savevm.c @@ -532,59 +532,85 @@ void qemu_put_byte(QEMUFile *f, int v) qemu_fflush(f); } -int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size1) +static void qemu_file_skip(QEMUFile *f, int size) { - int size, l; + if (f->buf_index + size <= f->buf_size) { + f->buf_index += size; + } +} + +static int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size, size_t offset) +{ + int pending; + int index; if (f->is_write) { abort(); } - size = size1; - while (size > 0) { - l = f->buf_size - f->buf_index; - if (l == 0) { - qemu_fill_buffer(f); - l = f->buf_size - f->buf_index; - if (l == 0) { - break; - } - } - if (l > size) { - l = size; + index = f->buf_index + offset; + pending = f->buf_size - index; + if (pending < size) { + qemu_fill_buffer(f); + index = f->buf_index + offset; + pending = f->buf_size - index; + } + + if (pending <= 0) { + return 0; + } + if (size > pending) { + size = pending; + } + + memcpy(buf, f->buf + index, size); + return size; +} + +int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size) +{ + int pending = size; + int done = 0; + + while (pending > 0) { + int res; + + res = qemu_peek_buffer(f, buf, pending, 0); + if (res == 0) { + return done; } - memcpy(buf, f->buf + f->buf_index, l); - f->buf_index += l; - buf += l; - size -= l; + qemu_file_skip(f, res); + buf += res; + pending -= res; + done += res; } - return size1 - size; + return done; } -static int qemu_peek_byte(QEMUFile *f) +static int qemu_peek_byte(QEMUFile *f, int offset) { + int index = f->buf_index + offset; + if (f->is_write) { abort(); } - if (f->buf_index >= f->buf_size) { + if (index >= f->buf_size) { qemu_fill_buffer(f); - if (f->buf_index >= f->buf_size) { + index = f->buf_index + offset; + if (index >= f->buf_size) { return 0; } } - return f->buf[f->buf_index]; + return f->buf[index]; } int qemu_get_byte(QEMUFile *f) { int result; - result = qemu_peek_byte(f); - - if (f->buf_index < f->buf_size) { - f->buf_index++; - } + result = qemu_peek_byte(f, 0); + qemu_file_skip(f, 1); return result; } @@ -1684,22 +1710,36 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, return 0; } - while (qemu_peek_byte(f) == QEMU_VM_SUBSECTION) { + while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) { char idstr[256]; int ret; - uint8_t version_id, len; + uint8_t version_id, len, size; const VMStateDescription *sub_vmsd; - qemu_get_byte(f); /* subsection */ - len = qemu_get_byte(f); - qemu_get_buffer(f, (uint8_t *)idstr, len); - idstr[len] = 0; - version_id = qemu_get_be32(f); + len = qemu_peek_byte(f, 1); + if (len < strlen(vmsd->name) + 1) { + /* subsection name has be be "section_name/a" */ + return 0; + } + size = qemu_peek_buffer(f, (uint8_t *)idstr, len, 2); + if (size != len) { + return 0; + } + idstr[size] = 0; + if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) { + /* it don't have a valid subsection name */ + return 0; + } sub_vmsd = vmstate_get_subsection(sub, idstr); if (sub_vmsd == NULL) { return -ENOENT; } + qemu_file_skip(f, 1); /* subsection */ + qemu_file_skip(f, 1); /* len */ + qemu_file_skip(f, len); /* idstr */ + version_id = qemu_get_be32(f); + assert(!sub_vmsd->subsections); ret = vmstate_load_state(f, sub_vmsd, opaque, version_id); if (ret) {