From 31f0360f1fd4ebc9dfcaed42d1c50d2448b4632e Mon Sep 17 00:00:00 2001 From: Tom Zanussi Date: Sat, 24 Aug 2013 15:31:34 +0000 Subject: wic: Add mic w/pykickstart This is the starting point for the implemention described in [YOCTO 3847] which came to the conclusion that it would make sense to use kickstart syntax to implement image creation in OpenEmbedded. I subsequently realized that there was an existing tool that already implemented image creation using kickstart syntax, the Tizen/Meego mic tool. As such, it made sense to use that as a starting point - this commit essentially just copies the relevant Python code from the MIC tool to the scripts/lib dir, where it can be accessed by the previously created wic tool. Most of this will be removed or renamed by later commits, since we're initially focusing on partitioning only. Care should be taken so that we can easily add back any additional functionality should we decide later to expand the tool, though (we may also want to contribute our local changes to the mic tool to the Tizen project if it makes sense, and therefore should avoid gratuitous changes to the original code if possible). Added the /mic subdir from Tizen mic repo as a starting point: git clone git://review.tizen.org/tools/mic.git For reference, the top commit: commit 20164175ddc234a17b8a12c33d04b012347b1530 Author: Gui Chen Date: Sun Jun 30 22:32:16 2013 -0400 bump up to 0.19.2 Also added the /plugins subdir, moved to under the /mic subdir (to match the default plugin_dir location in mic.conf.in, which was renamed to yocto-image.conf (moved and renamed by later patches) and put into /scripts. Signed-off-by: Tom Zanussi Signed-off-by: Saul Wold Signed-off-by: Richard Purdie --- scripts/lib/mic/utils/gpt_parser.py | 331 ++++++++++++++++++++++++++++++++++++ 1 file changed, 331 insertions(+) create mode 100644 scripts/lib/mic/utils/gpt_parser.py (limited to 'scripts/lib/mic/utils/gpt_parser.py') diff --git a/scripts/lib/mic/utils/gpt_parser.py b/scripts/lib/mic/utils/gpt_parser.py new file mode 100644 index 0000000000..5d43b70778 --- /dev/null +++ b/scripts/lib/mic/utils/gpt_parser.py @@ -0,0 +1,331 @@ +#!/usr/bin/python -tt +# +# Copyright (c) 2013 Intel, Inc. +# +# 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; version 2 of the License +# +# 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, write to the Free Software Foundation, Inc., 59 +# Temple Place - Suite 330, Boston, MA 02111-1307, USA. + +""" This module implements a simple GPT partitions parser which can read the +GPT header and the GPT partition table. """ + +import struct +import uuid +import binascii +from mic.utils.errors import MountError + +_GPT_HEADER_FORMAT = "<8s4sIIIQQQQ16sQIII" +_GPT_HEADER_SIZE = struct.calcsize(_GPT_HEADER_FORMAT) +_GPT_ENTRY_FORMAT = "<16s16sQQQ72s" +_GPT_ENTRY_SIZE = struct.calcsize(_GPT_ENTRY_FORMAT) +_SUPPORTED_GPT_REVISION = '\x00\x00\x01\x00' + +def _stringify_uuid(binary_uuid): + """ A small helper function to transform a binary UUID into a string + format. """ + + uuid_str = str(uuid.UUID(bytes_le = binary_uuid)) + + return uuid_str.upper() + +def _calc_header_crc(raw_hdr): + """ Calculate GPT header CRC32 checksum. The 'raw_hdr' parameter has to + be a list or a tuple containing all the elements of the GPT header in a + "raw" form, meaning that it should simply contain "unpacked" disk data. + """ + + raw_hdr = list(raw_hdr) + raw_hdr[3] = 0 + raw_hdr = struct.pack(_GPT_HEADER_FORMAT, *raw_hdr) + + return binascii.crc32(raw_hdr) & 0xFFFFFFFF + +def _validate_header(raw_hdr): + """ Validate the GPT header. The 'raw_hdr' parameter has to be a list or a + tuple containing all the elements of the GPT header in a "raw" form, + meaning that it should simply contain "unpacked" disk data. """ + + # Validate the signature + if raw_hdr[0] != 'EFI PART': + raise MountError("GPT partition table not found") + + # Validate the revision + if raw_hdr[1] != _SUPPORTED_GPT_REVISION: + raise MountError("Unsupported GPT revision '%s', supported revision " \ + "is '%s'" % \ + (binascii.hexlify(raw_hdr[1]), + binascii.hexlify(_SUPPORTED_GPT_REVISION))) + + # Validate header size + if raw_hdr[2] != _GPT_HEADER_SIZE: + raise MountError("Bad GPT header size: %d bytes, expected %d" % \ + (raw_hdr[2], _GPT_HEADER_SIZE)) + + crc = _calc_header_crc(raw_hdr) + if raw_hdr[3] != crc: + raise MountError("GPT header crc mismatch: %#x, should be %#x" % \ + (crc, raw_hdr[3])) + +class GptParser: + """ GPT partition table parser. Allows reading the GPT header and the + partition table, as well as modifying the partition table records. """ + + def __init__(self, disk_path, sector_size = 512): + """ The class constructor which accepts the following parameters: + * disk_path - full path to the disk image or device node + * sector_size - size of a disk sector in bytes """ + + self.sector_size = sector_size + self.disk_path = disk_path + + try: + self._disk_obj = open(disk_path, 'r+b') + except IOError as err: + raise MountError("Cannot open file '%s' for reading GPT " \ + "partitions: %s" % (disk_path, err)) + + def __del__(self): + """ The class destructor. """ + + self._disk_obj.close() + + def _read_disk(self, offset, size): + """ A helper function which reads 'size' bytes from offset 'offset' of + the disk and checks all the error conditions. """ + + self._disk_obj.seek(offset) + try: + data = self._disk_obj.read(size) + except IOError as err: + raise MountError("cannot read from '%s': %s" % \ + (self.disk_path, err)) + + if len(data) != size: + raise MountError("cannot read %d bytes from offset '%d' of '%s', " \ + "read only %d bytes" % \ + (size, offset, self.disk_path, len(data))) + + return data + + def _write_disk(self, offset, buf): + """ A helper function which writes buffer 'buf' to offset 'offset' of + the disk. This function takes care of unaligned writes and checks all + the error conditions. """ + + # Since we may be dealing with a block device, we only can write in + # 'self.sector_size' chunks. Find the aligned starting and ending + # disk offsets to read. + start = (offset / self.sector_size) * self.sector_size + end = ((start + len(buf)) / self.sector_size + 1) * self.sector_size + + data = self._read_disk(start, end - start) + off = offset - start + data = data[:off] + buf + data[off + len(buf):] + + self._disk_obj.seek(start) + try: + self._disk_obj.write(data) + except IOError as err: + raise MountError("cannot write to '%s': %s" % (self.disk_path, err)) + + def read_header(self, primary = True): + """ Read and verify the GPT header and return a dictionary containing + the following elements: + + 'signature' : header signature + 'revision' : header revision + 'hdr_size' : header size in bytes + 'hdr_crc' : header CRC32 + 'hdr_lba' : LBA of this header + 'hdr_offs' : byte disk offset of this header + 'backup_lba' : backup header LBA + 'backup_offs' : byte disk offset of backup header + 'first_lba' : first usable LBA for partitions + 'first_offs' : first usable byte disk offset for partitions + 'last_lba' : last usable LBA for partitions + 'last_offs' : last usable byte disk offset for partitions + 'disk_uuid' : UUID of the disk + 'ptable_lba' : starting LBA of array of partition entries + 'ptable_offs' : disk byte offset of the start of the partition table + 'ptable_size' : partition table size in bytes + 'entries_cnt' : number of available partition table entries + 'entry_size' : size of a single partition entry + 'ptable_crc' : CRC32 of the partition table + 'primary' : a boolean, if 'True', this is the primary GPT header, + if 'False' - the secondary + 'primary_str' : contains string "primary" if this is the primary GPT + header, and "backup" otherwise + + This dictionary corresponds to the GPT header format. Please, see the + UEFI standard for the description of these fields. + + If the 'primary' parameter is 'True', the primary GPT header is read, + otherwise the backup GPT header is read instead. """ + + # Read and validate the primary GPT header + raw_hdr = self._read_disk(self.sector_size, _GPT_HEADER_SIZE) + raw_hdr = struct.unpack(_GPT_HEADER_FORMAT, raw_hdr) + _validate_header(raw_hdr) + primary_str = "primary" + + if not primary: + # Read and validate the backup GPT header + raw_hdr = self._read_disk(raw_hdr[6] * self.sector_size, _GPT_HEADER_SIZE) + raw_hdr = struct.unpack(_GPT_HEADER_FORMAT, raw_hdr) + _validate_header(raw_hdr) + primary_str = "backup" + + return { 'signature' : raw_hdr[0], + 'revision' : raw_hdr[1], + 'hdr_size' : raw_hdr[2], + 'hdr_crc' : raw_hdr[3], + 'hdr_lba' : raw_hdr[5], + 'hdr_offs' : raw_hdr[5] * self.sector_size, + 'backup_lba' : raw_hdr[6], + 'backup_offs' : raw_hdr[6] * self.sector_size, + 'first_lba' : raw_hdr[7], + 'first_offs' : raw_hdr[7] * self.sector_size, + 'last_lba' : raw_hdr[8], + 'last_offs' : raw_hdr[8] * self.sector_size, + 'disk_uuid' :_stringify_uuid(raw_hdr[9]), + 'ptable_lba' : raw_hdr[10], + 'ptable_offs' : raw_hdr[10] * self.sector_size, + 'ptable_size' : raw_hdr[11] * raw_hdr[12], + 'entries_cnt' : raw_hdr[11], + 'entry_size' : raw_hdr[12], + 'ptable_crc' : raw_hdr[13], + 'primary' : primary, + 'primary_str' : primary_str } + + def _read_raw_ptable(self, header): + """ Read and validate primary or backup partition table. The 'header' + argument is the GPT header. If it is the primary GPT header, then the + primary partition table is read and validated, otherwise - the backup + one. The 'header' argument is a dictionary which is returned by the + 'read_header()' method. """ + + raw_ptable = self._read_disk(header['ptable_offs'], + header['ptable_size']) + + crc = binascii.crc32(raw_ptable) & 0xFFFFFFFF + if crc != header['ptable_crc']: + raise MountError("Partition table at LBA %d (%s) is corrupted" % \ + (header['ptable_lba'], header['primary_str'])) + + return raw_ptable + + def get_partitions(self, primary = True): + """ This is a generator which parses the GPT partition table and + generates the following dictionary for each partition: + + 'index' : the index of the partition table endry + 'offs' : byte disk offset of the partition table entry + 'type_uuid' : partition type UUID + 'part_uuid' : partition UUID + 'first_lba' : the first LBA + 'last_lba' : the last LBA + 'flags' : attribute flags + 'name' : partition name + 'primary' : a boolean, if 'True', this is the primary partition + table, if 'False' - the secondary + 'primary_str' : contains string "primary" if this is the primary GPT + header, and "backup" otherwise + + This dictionary corresponds to the GPT header format. Please, see the + UEFI standard for the description of these fields. + + If the 'primary' parameter is 'True', partitions from the primary GPT + partition table are generated, otherwise partitions from the backup GPT + partition table are generated. """ + + if primary: + primary_str = "primary" + else: + primary_str = "backup" + + header = self.read_header(primary) + raw_ptable = self._read_raw_ptable(header) + + for index in xrange(0, header['entries_cnt']): + start = header['entry_size'] * index + end = start + header['entry_size'] + raw_entry = struct.unpack(_GPT_ENTRY_FORMAT, raw_ptable[start:end]) + + if raw_entry[2] == 0 or raw_entry[3] == 0: + continue + + part_name = str(raw_entry[5].decode('UTF-16').split('\0', 1)[0]) + + yield { 'index' : index, + 'offs' : header['ptable_offs'] + start, + 'type_uuid' : _stringify_uuid(raw_entry[0]), + 'part_uuid' : _stringify_uuid(raw_entry[1]), + 'first_lba' : raw_entry[2], + 'last_lba' : raw_entry[3], + 'flags' : raw_entry[4], + 'name' : part_name, + 'primary' : primary, + 'primary_str' : primary_str } + + def _change_partition(self, header, entry): + """ A helper function for 'change_partitions()' which changes a + a paricular instance of the partition table (primary or backup). """ + + if entry['index'] >= header['entries_cnt']: + raise MountError("Partition table at LBA %d has only %d " \ + "records cannot change record number %d" % \ + (header['entries_cnt'], entry['index'])) + # Read raw GPT header + raw_hdr = self._read_disk(header['hdr_offs'], _GPT_HEADER_SIZE) + raw_hdr = list(struct.unpack(_GPT_HEADER_FORMAT, raw_hdr)) + _validate_header(raw_hdr) + + # Prepare the new partition table entry + raw_entry = struct.pack(_GPT_ENTRY_FORMAT, + uuid.UUID(entry['type_uuid']).bytes_le, + uuid.UUID(entry['part_uuid']).bytes_le, + entry['first_lba'], + entry['last_lba'], + entry['flags'], + entry['name'].encode('UTF-16')) + + # Write the updated entry to the disk + entry_offs = header['ptable_offs'] + \ + header['entry_size'] * entry['index'] + self._write_disk(entry_offs, raw_entry) + + # Calculate and update partition table CRC32 + raw_ptable = self._read_disk(header['ptable_offs'], + header['ptable_size']) + raw_hdr[13] = binascii.crc32(raw_ptable) & 0xFFFFFFFF + + # Calculate and update the GPT header CRC + raw_hdr[3] = _calc_header_crc(raw_hdr) + + # Write the updated header to the disk + raw_hdr = struct.pack(_GPT_HEADER_FORMAT, *raw_hdr) + self._write_disk(header['hdr_offs'], raw_hdr) + + def change_partition(self, entry): + """ Change a GPT partition. The 'entry' argument has the same format as + 'get_partitions()' returns. This function simply changes the partition + table record corresponding to 'entry' in both, the primary and the + backup GPT partition tables. The parition table CRC is re-calculated + and the GPT headers are modified accordingly. """ + + # Change the primary partition table + header = self.read_header(True) + self._change_partition(header, entry) + + # Change the backup partition table + header = self.read_header(False) + self._change_partition(header, entry) -- cgit v1.2.3