From d5262c712488674fba74a749e81894e098226bfa Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Sat, 6 Jun 2020 11:17:56 +0300 Subject: [PATCH] qcow2.py: move qcow2 format classes to separate module We are going to enhance qcow2 format parsing by adding more structure classes. Let's split format parsing from utility code. Signed-off-by: Vladimir Sementsov-Ogievskiy Message-Id: <20200606081806.23897-4-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake Signed-off-by: Eric Blake --- tests/qemu-iotests/qcow2.py | 160 +------------------------- tests/qemu-iotests/qcow2_format.py | 173 +++++++++++++++++++++++++++++ 2 files changed, 177 insertions(+), 156 deletions(-) create mode 100644 tests/qemu-iotests/qcow2_format.py diff --git a/tests/qemu-iotests/qcow2.py b/tests/qemu-iotests/qcow2.py index 2da434a013..e968869ea6 100755 --- a/tests/qemu-iotests/qcow2.py +++ b/tests/qemu-iotests/qcow2.py @@ -17,163 +17,11 @@ # import sys -import struct -import string - -class QcowHeaderExtension: - - def __init__(self, magic, length, data): - if length % 8 != 0: - padding = 8 - (length % 8) - data += b"\0" * padding - - self.magic = magic - self.length = length - self.data = data - - @classmethod - def create(cls, magic, data): - return QcowHeaderExtension(magic, len(data), data) - - -class QcowHeader: - - uint32_t = 'I' - uint64_t = 'Q' - - fields = [ - # Version 2 header fields - [uint32_t, '%#x', 'magic'], - [uint32_t, '%d', 'version'], - [uint64_t, '%#x', 'backing_file_offset'], - [uint32_t, '%#x', 'backing_file_size'], - [uint32_t, '%d', 'cluster_bits'], - [uint64_t, '%d', 'size'], - [uint32_t, '%d', 'crypt_method'], - [uint32_t, '%d', 'l1_size'], - [uint64_t, '%#x', 'l1_table_offset'], - [uint64_t, '%#x', 'refcount_table_offset'], - [uint32_t, '%d', 'refcount_table_clusters'], - [uint32_t, '%d', 'nb_snapshots'], - [uint64_t, '%#x', 'snapshot_offset'], - - # Version 3 header fields - [uint64_t, 'mask', 'incompatible_features'], - [uint64_t, 'mask', 'compatible_features'], - [uint64_t, 'mask', 'autoclear_features'], - [uint32_t, '%d', 'refcount_order'], - [uint32_t, '%d', 'header_length'], - ] - - fmt = '>' + ''.join(field[0] for field in fields) - - def __init__(self, fd): - - buf_size = struct.calcsize(QcowHeader.fmt) - - fd.seek(0) - buf = fd.read(buf_size) - - header = struct.unpack(QcowHeader.fmt, buf) - self.__dict__ = dict((field[2], header[i]) - for i, field in enumerate(QcowHeader.fields)) - - self.set_defaults() - self.cluster_size = 1 << self.cluster_bits - - fd.seek(self.header_length) - self.load_extensions(fd) - - if self.backing_file_offset: - fd.seek(self.backing_file_offset) - self.backing_file = fd.read(self.backing_file_size) - else: - self.backing_file = None - - def set_defaults(self): - if self.version == 2: - self.incompatible_features = 0 - self.compatible_features = 0 - self.autoclear_features = 0 - self.refcount_order = 4 - self.header_length = 72 - - def load_extensions(self, fd): - self.extensions = [] - - if self.backing_file_offset != 0: - end = min(self.cluster_size, self.backing_file_offset) - else: - end = self.cluster_size - - while fd.tell() < end: - (magic, length) = struct.unpack('>II', fd.read(8)) - if magic == 0: - break - else: - padded = (length + 7) & ~7 - data = fd.read(padded) - self.extensions.append(QcowHeaderExtension(magic, length, - data)) - - def update_extensions(self, fd): - - fd.seek(self.header_length) - extensions = self.extensions - extensions.append(QcowHeaderExtension(0, 0, b"")) - for ex in extensions: - buf = struct.pack('>II', ex.magic, ex.length) - fd.write(buf) - fd.write(ex.data) - - if self.backing_file is not None: - self.backing_file_offset = fd.tell() - fd.write(self.backing_file) - - if fd.tell() > self.cluster_size: - raise Exception("I think I just broke the image...") - - def update(self, fd): - header_bytes = self.header_length - - self.update_extensions(fd) - - fd.seek(0) - header = tuple(self.__dict__[f] for t, p, f in QcowHeader.fields) - buf = struct.pack(QcowHeader.fmt, *header) - buf = buf[0:header_bytes-1] - fd.write(buf) - - def dump(self): - for f in QcowHeader.fields: - value = self.__dict__[f[2]] - if f[1] == 'mask': - bits = [] - for bit in range(64): - if value & (1 << bit): - bits.append(bit) - value_str = str(bits) - else: - value_str = f[1] % value - - print("%-25s" % f[2], value_str) - print("") - - def dump_extensions(self): - for ex in self.extensions: - - data = ex.data[:ex.length] - if all(c in string.printable.encode('ascii') for c in data): - data = "'%s'" % data.decode('ascii') - else: - data = "" - - print("Header extension:") - print("%-25s %#x" % ("magic", ex.magic)) - print("%-25s %d" % ("length", ex.length)) - print("%-25s %s" % ("data", data)) - print("") +from qcow2_format import ( + QcowHeader, + QcowHeaderExtension +) def cmd_dump_header(fd): diff --git a/tests/qemu-iotests/qcow2_format.py b/tests/qemu-iotests/qcow2_format.py new file mode 100644 index 0000000000..0e517c1bbc --- /dev/null +++ b/tests/qemu-iotests/qcow2_format.py @@ -0,0 +1,173 @@ +# Library for manipulations with qcow2 image +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . +# + +import struct +import string + + +class QcowHeaderExtension: + + def __init__(self, magic, length, data): + if length % 8 != 0: + padding = 8 - (length % 8) + data += b"\0" * padding + + self.magic = magic + self.length = length + self.data = data + + @classmethod + def create(cls, magic, data): + return QcowHeaderExtension(magic, len(data), data) + + +class QcowHeader: + + uint32_t = 'I' + uint64_t = 'Q' + + fields = [ + # Version 2 header fields + [uint32_t, '%#x', 'magic'], + [uint32_t, '%d', 'version'], + [uint64_t, '%#x', 'backing_file_offset'], + [uint32_t, '%#x', 'backing_file_size'], + [uint32_t, '%d', 'cluster_bits'], + [uint64_t, '%d', 'size'], + [uint32_t, '%d', 'crypt_method'], + [uint32_t, '%d', 'l1_size'], + [uint64_t, '%#x', 'l1_table_offset'], + [uint64_t, '%#x', 'refcount_table_offset'], + [uint32_t, '%d', 'refcount_table_clusters'], + [uint32_t, '%d', 'nb_snapshots'], + [uint64_t, '%#x', 'snapshot_offset'], + + # Version 3 header fields + [uint64_t, 'mask', 'incompatible_features'], + [uint64_t, 'mask', 'compatible_features'], + [uint64_t, 'mask', 'autoclear_features'], + [uint32_t, '%d', 'refcount_order'], + [uint32_t, '%d', 'header_length'], + ] + + fmt = '>' + ''.join(field[0] for field in fields) + + def __init__(self, fd): + + buf_size = struct.calcsize(QcowHeader.fmt) + + fd.seek(0) + buf = fd.read(buf_size) + + header = struct.unpack(QcowHeader.fmt, buf) + self.__dict__ = dict((field[2], header[i]) + for i, field in enumerate(QcowHeader.fields)) + + self.set_defaults() + self.cluster_size = 1 << self.cluster_bits + + fd.seek(self.header_length) + self.load_extensions(fd) + + if self.backing_file_offset: + fd.seek(self.backing_file_offset) + self.backing_file = fd.read(self.backing_file_size) + else: + self.backing_file = None + + def set_defaults(self): + if self.version == 2: + self.incompatible_features = 0 + self.compatible_features = 0 + self.autoclear_features = 0 + self.refcount_order = 4 + self.header_length = 72 + + def load_extensions(self, fd): + self.extensions = [] + + if self.backing_file_offset != 0: + end = min(self.cluster_size, self.backing_file_offset) + else: + end = self.cluster_size + + while fd.tell() < end: + (magic, length) = struct.unpack('>II', fd.read(8)) + if magic == 0: + break + else: + padded = (length + 7) & ~7 + data = fd.read(padded) + self.extensions.append(QcowHeaderExtension(magic, length, + data)) + + def update_extensions(self, fd): + + fd.seek(self.header_length) + extensions = self.extensions + extensions.append(QcowHeaderExtension(0, 0, b"")) + for ex in extensions: + buf = struct.pack('>II', ex.magic, ex.length) + fd.write(buf) + fd.write(ex.data) + + if self.backing_file is not None: + self.backing_file_offset = fd.tell() + fd.write(self.backing_file) + + if fd.tell() > self.cluster_size: + raise Exception("I think I just broke the image...") + + def update(self, fd): + header_bytes = self.header_length + + self.update_extensions(fd) + + fd.seek(0) + header = tuple(self.__dict__[f] for t, p, f in QcowHeader.fields) + buf = struct.pack(QcowHeader.fmt, *header) + buf = buf[0:header_bytes-1] + fd.write(buf) + + def dump(self): + for f in QcowHeader.fields: + value = self.__dict__[f[2]] + if f[1] == 'mask': + bits = [] + for bit in range(64): + if value & (1 << bit): + bits.append(bit) + value_str = str(bits) + else: + value_str = f[1] % value + + print("%-25s" % f[2], value_str) + print("") + + def dump_extensions(self): + for ex in self.extensions: + + data = ex.data[:ex.length] + if all(c in string.printable.encode('ascii') for c in data): + data = "'%s'" % data.decode('ascii') + else: + data = "" + + print("Header extension:") + print("%-25s %#x" % ("magic", ex.magic)) + print("%-25s %d" % ("length", ex.length)) + print("%-25s %s" % ("data", data)) + print("")