+++ /dev/null
-# Copyright (c) 2012-2013 Intel, Inc.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License, version 2,
-# as published by the Free Software Foundation.
-#
-# 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.
-
-"""
-This module implements the block map (bmap) creation functionality and provides
-the corresponding API in form of the 'BmapCreate' class.
-
-The idea is that while images files may generally be very large (e.g., 4GiB),
-they may nevertheless contain only little real data, e.g., 512MiB. This data
-are files, directories, file-system meta-data, partition table, etc. When
-copying the image to the target device, you do not have to copy all the 4GiB of
-data, you can copy only 512MiB of it, which is 4 times less, so copying should
-presumably be 4 times faster.
-
-The block map file is an XML file which contains a list of blocks which have to
-be copied to the target device. The other blocks are not used and there is no
-need to copy them. The XML file also contains some additional information like
-block size, image size, count of mapped blocks, etc. There are also many
-commentaries, so it is human-readable.
-
-The image has to be a sparse file. Generally, this means that when you generate
-this image file, you should start with a huge sparse file which contains a
-single hole spanning the entire file. Then you should partition it, write all
-the data (probably by means of loop-back mounting the image or parts of it),
-etc. The end result should be a sparse file where mapped areas represent useful
-parts of the image and holes represent useless parts of the image, which do not
-have to be copied when copying the image to the target device.
-
-This module uses the FIBMAP ioctl to detect holes.
-"""
-
-# Disable the following pylint recommendations:
-# * Too many instance attributes - R0902
-# * Too few public methods - R0903
-# pylint: disable=R0902,R0903
-
-import hashlib
-import logging
-from mic.utils.misc import human_size
-from mic.utils import Filemap
-
-# The bmap format version we generate.
-#
-# Changelog:
-# o 1.3 -> 2.0:
-# Support SHA256 and SHA512 checksums, in 1.3 only SHA1 was supported.
-# "BmapFileChecksum" is used instead of "BmapFileSHA1", and "chksum="
-# attribute is used instead "sha1=". Introduced "ChecksumType" tag. This is
-# an incompatible change.
-# Note, bmap format 1.4 is identical to 2.0. Version 1.4 was a mistake,
-# instead of incrementing the major version number, we incremented minor
-# version number. Unfortunately, the mistake slipped into bmap-tools version
-# 3.0, and was only fixed in bmap-tools v3.1.
-SUPPORTED_BMAP_VERSION = "2.0"
-
-_BMAP_START_TEMPLATE = \
-"""<?xml version="1.0" ?>
-<!-- This file contains the block map for an image file, which is basically
- a list of useful (mapped) block numbers in the image file. In other words,
- it lists only those blocks which contain data (boot sector, partition
- table, file-system metadata, files, directories, extents, etc). These
- blocks have to be copied to the target device. The other blocks do not
- contain any useful data and do not have to be copied to the target
- device.
-
- The block map an optimization which allows to copy or flash the image to
- the image quicker than copying of flashing the entire image. This is
- because with bmap less data is copied: <MappedBlocksCount> blocks instead
- of <BlocksCount> blocks.
-
- Besides the machine-readable data, this file contains useful commentaries
- which contain human-readable information like image size, percentage of
- mapped data, etc.
-
- The 'version' attribute is the block map file format version in the
- 'major.minor' format. The version major number is increased whenever an
- incompatible block map format change is made. The minor number changes
- in case of minor backward-compatible changes. -->
-
-<bmap version="%s">
- <!-- Image size in bytes: %s -->
- <ImageSize> %u </ImageSize>
-
- <!-- Size of a block in bytes -->
- <BlockSize> %u </BlockSize>
-
- <!-- Count of blocks in the image file -->
- <BlocksCount> %u </BlocksCount>
-
-"""
-
-class Error(Exception):
- """
- A class for exceptions generated by this module. We currently support only
- one type of exceptions, and we basically throw human-readable problem
- description in case of errors.
- """
- pass
-
-class BmapCreate(object):
- """
- This class implements the bmap creation functionality. To generate a bmap
- for an image (which is supposedly a sparse file), you should first create
- an instance of 'BmapCreate' and provide:
-
- * full path or a file-like object of the image to create bmap for
- * full path or a file object to use for writing the results to
-
- Then you should invoke the 'generate()' method of this class. It will use
- the FIEMAP ioctl to generate the bmap.
- """
-
- def __init__(self, image, bmap, chksum_type="sha256", log=None):
- """
- Initialize a class instance:
- * image - full path or a file-like object of the image to create bmap
- for
- * bmap - full path or a file object to use for writing the resulting
- bmap to
- * chksum - type of the check sum to use in the bmap file (all checksum
- types which python's "hashlib" module supports are allowed).
- * log - the logger object to use for printing messages.
- """
-
- self._log = log
- if self._log is None:
- self._log = logging.getLogger(__name__)
-
- self.image_size = None
- self.image_size_human = None
- self.block_size = None
- self.blocks_cnt = None
- self.mapped_cnt = None
- self.mapped_size = None
- self.mapped_size_human = None
- self.mapped_percent = None
-
- self._mapped_count_pos1 = None
- self._mapped_count_pos2 = None
- self._chksum_pos = None
-
- self._f_image_needs_close = False
- self._f_bmap_needs_close = False
-
- self._cs_type = chksum_type.lower()
- try:
- self._cs_len = len(hashlib.new(self._cs_type).hexdigest())
- except ValueError as err:
- raise Error("cannot initialize hash function \"%s\": %s" %
- (self._cs_type, err))
-
- if hasattr(image, "read"):
- self._f_image = image
- self._image_path = image.name
- else:
- self._image_path = image
- self._open_image_file()
-
- if hasattr(bmap, "read"):
- self._f_bmap = bmap
- self._bmap_path = bmap.name
- else:
- self._bmap_path = bmap
- self._open_bmap_file()
-
- try:
- self.filemap = Filemap.filemap(self._f_image, self._log)
- except (Filemap.Error, Filemap.ErrorNotSupp) as err:
- raise Error("cannot generate bmap: %s" % err)
-
- self.image_size = self.filemap.image_size
- self.image_size_human = human_size(self.image_size)
- if self.image_size == 0:
- raise Error("cannot generate bmap for zero-sized image file '%s'"
- % self._image_path)
-
- self.block_size = self.filemap.block_size
- self.blocks_cnt = self.filemap.blocks_cnt
-
- def __del__(self):
- """The class destructor which closes the opened files."""
- if self._f_image_needs_close:
- self._f_image.close()
- if self._f_bmap_needs_close:
- self._f_bmap.close()
-
- def _open_image_file(self):
- """Open the image file."""
- try:
- self._f_image = open(self._image_path, 'rb')
- except IOError as err:
- raise Error("cannot open image file '%s': %s"
- % (self._image_path, err))
-
- self._f_image_needs_close = True
-
- def _open_bmap_file(self):
- """Open the bmap file."""
- try:
- self._f_bmap = open(self._bmap_path, 'w+')
- except IOError as err:
- raise Error("cannot open bmap file '%s': %s"
- % (self._bmap_path, err))
-
- self._f_bmap_needs_close = True
-
- def _bmap_file_start(self):
- """
- A helper function which generates the starting contents of the block
- map file: the header comment, image size, block size, etc.
- """
-
- # We do not know the amount of mapped blocks at the moment, so just put
- # whitespaces instead of real numbers. Assume the longest possible
- # numbers.
-
- xml = _BMAP_START_TEMPLATE \
- % (SUPPORTED_BMAP_VERSION, self.image_size_human,
- self.image_size, self.block_size, self.blocks_cnt)
- xml += " <!-- Count of mapped blocks: "
-
- self._f_bmap.write(xml)
- self._mapped_count_pos1 = self._f_bmap.tell()
-
- xml = "%s or %s -->\n" % (' ' * len(self.image_size_human),
- ' ' * len("100.0%"))
- xml += " <MappedBlocksCount> "
-
- self._f_bmap.write(xml)
- self._mapped_count_pos2 = self._f_bmap.tell()
-
- xml = "%s </MappedBlocksCount>\n\n" % (' ' * len(str(self.blocks_cnt)))
-
- # pylint: disable=C0301
- xml += " <!-- Type of checksum used in this file -->\n"
- xml += " <ChecksumType> %s </ChecksumType>\n\n" % self._cs_type
-
- xml += " <!-- The checksum of this bmap file. When it is calculated, the value of\n"
- xml += " the checksum has be zero (all ASCII \"0\" symbols). -->\n"
- xml += " <BmapFileChecksum> "
-
- self._f_bmap.write(xml)
- self._chksum_pos = self._f_bmap.tell()
-
- xml = "0" * self._cs_len + " </BmapFileChecksum>\n\n"
- xml += " <!-- The block map which consists of elements which may either be a\n"
- xml += " range of blocks or a single block. The 'chksum' attribute\n"
- xml += " (if present) is the checksum of this blocks range. -->\n"
- xml += " <BlockMap>\n"
- # pylint: enable=C0301
-
- self._f_bmap.write(xml)
-
- def _bmap_file_end(self):
- """
- A helper function which generates the final parts of the block map
- file: the ending tags and the information about the amount of mapped
- blocks.
- """
-
- xml = " </BlockMap>\n"
- xml += "</bmap>\n"
-
- self._f_bmap.write(xml)
-
- self._f_bmap.seek(self._mapped_count_pos1)
- self._f_bmap.write("%s or %.1f%%"
- % (self.mapped_size_human, self.mapped_percent))
-
- self._f_bmap.seek(self._mapped_count_pos2)
- self._f_bmap.write("%u" % self.mapped_cnt)
-
- self._f_bmap.seek(0)
- hash_obj = hashlib.new(self._cs_type)
- hash_obj.update(self._f_bmap.read())
- chksum = hash_obj.hexdigest()
- self._f_bmap.seek(self._chksum_pos)
- self._f_bmap.write("%s" % chksum)
-
- def _calculate_chksum(self, first, last):
- """
- A helper function which calculates checksum for the range of blocks of
- the image file: from block 'first' to block 'last'.
- """
-
- start = first * self.block_size
- end = (last + 1) * self.block_size
-
- self._f_image.seek(start)
- hash_obj = hashlib.new(self._cs_type)
-
- chunk_size = 1024*1024
- to_read = end - start
- read = 0
-
- while read < to_read:
- if read + chunk_size > to_read:
- chunk_size = to_read - read
- chunk = self._f_image.read(chunk_size)
- hash_obj.update(chunk)
- read += chunk_size
-
- return hash_obj.hexdigest()
-
- def generate(self, include_checksums=True):
- """
- Generate bmap for the image file. If 'include_checksums' is 'True',
- also generate checksums for block ranges.
- """
-
- # Save image file position in order to restore it at the end
- image_pos = self._f_image.tell()
-
- self._bmap_file_start()
-
- # Generate the block map and write it to the XML block map
- # file as we go.
- self.mapped_cnt = 0
- for first, last in self.filemap.get_mapped_ranges(0, self.blocks_cnt):
- self.mapped_cnt += last - first + 1
- if include_checksums:
- chksum = self._calculate_chksum(first, last)
- chksum = " chksum=\"%s\"" % chksum
- else:
- chksum = ""
-
- if first != last:
- self._f_bmap.write(" <Range%s> %s-%s </Range>\n"
- % (chksum, first, last))
- else:
- self._f_bmap.write(" <Range%s> %s </Range>\n"
- % (chksum, first))
-
- self.mapped_size = self.mapped_cnt * self.block_size
- self.mapped_size_human = human_size(self.mapped_size)
- self.mapped_percent = (self.mapped_cnt * 100.0) / self.blocks_cnt
-
- self._bmap_file_end()
-
- try:
- self._f_bmap.flush()
- except IOError as err:
- raise Error("cannot flush the bmap file '%s': %s"
- % (self._bmap_path, err))
-
- self._f_image.seek(image_pos)
+++ /dev/null
-# Copyright (c) 2012 Intel, Inc.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License, version 2,
-# as published by the Free Software Foundation.
-#
-# 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.
-
-"""
-This module implements python implements a way to get file block. Two methods
-are supported - the FIEMAP ioctl and the 'SEEK_HOLE / SEEK_DATA' features of
-the file seek syscall. The former is implemented by the 'FilemapFiemap' class,
-the latter is implemented by the 'FilemapSeek' class. Both classes provide the
-same API. The 'filemap' function automatically selects which class can be used
-and returns an instance of the class.
-"""
-
-# Disable the following pylint recommendations:
-# * Too many instance attributes (R0902)
-# pylint: disable=R0902
-
-import os
-import struct
-import array
-import fcntl
-import tempfile
-import logging
-from mic.utils.misc import get_block_size
-
-
-class ErrorNotSupp(Exception):
- """
- An exception of this type is raised when the 'FIEMAP' or 'SEEK_HOLE' feature
- is not supported either by the kernel or the file-system.
- """
- pass
-
-class Error(Exception):
- """A class for all the other exceptions raised by this module."""
- pass
-
-
-class _FilemapBase(object):
- """
- This is a base class for a couple of other classes in this module. This
- class simply performs the common parts of the initialization process: opens
- the image file, gets its size, etc. The 'log' parameter is the logger object
- to use for printing messages.
- """
-
- def __init__(self, image, log=None):
- """
- Initialize a class instance. The 'image' argument is full path to the
- file or file object to operate on.
- """
-
- self._log = log
- if self._log is None:
- self._log = logging.getLogger(__name__)
-
- self._f_image_needs_close = False
-
- if hasattr(image, "fileno"):
- self._f_image = image
- self._image_path = image.name
- else:
- self._image_path = image
- self._open_image_file()
-
- try:
- self.image_size = os.fstat(self._f_image.fileno()).st_size
- except IOError as err:
- raise Error("cannot get information about file '%s': %s"
- % (self._f_image.name, err))
-
- try:
- self.block_size = get_block_size(self._f_image)
- except IOError as err:
- raise Error("cannot get block size for '%s': %s"
- % (self._image_path, err))
-
- self.blocks_cnt = self.image_size + self.block_size - 1
- self.blocks_cnt /= self.block_size
-
- try:
- self._f_image.flush()
- except IOError as err:
- raise Error("cannot flush image file '%s': %s"
- % (self._image_path, err))
-
- try:
- os.fsync(self._f_image.fileno()),
- except OSError as err:
- raise Error("cannot synchronize image file '%s': %s "
- % (self._image_path, err.strerror))
-
- self._log.debug("opened image \"%s\"" % self._image_path)
- self._log.debug("block size %d, blocks count %d, image size %d"
- % (self.block_size, self.blocks_cnt, self.image_size))
-
- def __del__(self):
- """The class destructor which just closes the image file."""
- if self._f_image_needs_close:
- self._f_image.close()
-
- def _open_image_file(self):
- """Open the image file."""
- try:
- self._f_image = open(self._image_path, 'rb')
- except IOError as err:
- raise Error("cannot open image file '%s': %s"
- % (self._image_path, err))
-
- self._f_image_needs_close = True
-
- def block_is_mapped(self, block): # pylint: disable=W0613,R0201
- """
- This method has has to be implemented by child classes. It returns
- 'True' if block number 'block' of the image file is mapped and 'False'
- otherwise.
- """
-
- raise Error("the method is not implemented")
-
- def block_is_unmapped(self, block): # pylint: disable=W0613,R0201
- """
- This method has has to be implemented by child classes. It returns
- 'True' if block number 'block' of the image file is not mapped (hole)
- and 'False' otherwise.
- """
-
- raise Error("the method is not implemented")
-
- def get_mapped_ranges(self, start, count): # pylint: disable=W0613,R0201
- """
- This method has has to be implemented by child classes. This is a
- generator which yields ranges of mapped blocks in the file. The ranges
- are tuples of 2 elements: [first, last], where 'first' is the first
- mapped block and 'last' is the last mapped block.
-
- The ranges are yielded for the area of the file of size 'count' blocks,
- starting from block 'start'.
- """
-
- raise Error("the method is not implemented")
-
- def get_unmapped_ranges(self, start, count): # pylint: disable=W0613,R0201
- """
- This method has has to be implemented by child classes. Just like
- 'get_mapped_ranges()', but yields unmapped block ranges instead
- (holes).
- """
-
- raise Error("the method is not implemented")
-
-
-# The 'SEEK_HOLE' and 'SEEK_DATA' options of the file seek system call
-_SEEK_DATA = 3
-_SEEK_HOLE = 4
-
-def _lseek(file_obj, offset, whence):
- """This is a helper function which invokes 'os.lseek' for file object
- 'file_obj' and with specified 'offset' and 'whence'. The 'whence'
- argument is supposed to be either '_SEEK_DATA' or '_SEEK_HOLE'. When
- there is no more data or hole starting from 'offset', this function
- returns '-1'. Otherwise the data or hole position is returned."""
-
- try:
- return os.lseek(file_obj.fileno(), offset, whence)
- except OSError as err:
- # The 'lseek' system call returns the ENXIO if there is no data or
- # hole starting from the specified offset.
- if err.errno == os.errno.ENXIO:
- return -1
- elif err.errno == os.errno.EINVAL:
- raise ErrorNotSupp("the kernel or file-system does not support "
- "\"SEEK_HOLE\" and \"SEEK_DATA\"")
- else:
- raise
-
-class FilemapSeek(_FilemapBase):
- """
- This class uses the 'SEEK_HOLE' and 'SEEK_DATA' to find file block mapping.
- Unfortunately, the current implementation requires the caller to have write
- access to the image file.
- """
-
- def __init__(self, image, log=None):
- """Refer the '_FilemapBase' class for the documentation."""
-
- # Call the base class constructor first
- _FilemapBase.__init__(self, image, log)
- self._log.debug("FilemapSeek: initializing")
-
- self._probe_seek_hole()
-
- def _probe_seek_hole(self):
- """
- Check whether the system implements 'SEEK_HOLE' and 'SEEK_DATA'.
- Unfortunately, there seems to be no clean way for detecting this,
- because often the system just fakes them by just assuming that all
- files are fully mapped, so 'SEEK_HOLE' always returns EOF and
- 'SEEK_DATA' always returns the requested offset.
-
- I could not invent a better way of detecting the fake 'SEEK_HOLE'
- implementation than just to create a temporary file in the same
- directory where the image file resides. It would be nice to change this
- to something better.
- """
-
- directory = os.path.dirname(self._image_path)
-
- try:
- tmp_obj = tempfile.TemporaryFile("w+", dir=directory)
- except IOError as err:
- raise ErrorNotSupp("cannot create a temporary in \"%s\": %s"
- % (directory, err))
-
- try:
- os.ftruncate(tmp_obj.fileno(), self.block_size)
- except OSError as err:
- raise ErrorNotSupp("cannot truncate temporary file in \"%s\": %s"
- % (directory, err))
-
- offs = _lseek(tmp_obj, 0, _SEEK_HOLE)
- if offs != 0:
- # We are dealing with the stub 'SEEK_HOLE' implementation which
- # always returns EOF.
- self._log.debug("lseek(0, SEEK_HOLE) returned %d" % offs)
- raise ErrorNotSupp("the file-system does not support "
- "\"SEEK_HOLE\" and \"SEEK_DATA\" but only "
- "provides a stub implementation")
-
- tmp_obj.close()
-
- def block_is_mapped(self, block):
- """Refer the '_FilemapBase' class for the documentation."""
- offs = _lseek(self._f_image, block * self.block_size, _SEEK_DATA)
- if offs == -1:
- result = False
- else:
- result = (offs / self.block_size == block)
-
- self._log.debug("FilemapSeek: block_is_mapped(%d) returns %s"
- % (block, result))
- return result
-
- def block_is_unmapped(self, block):
- """Refer the '_FilemapBase' class for the documentation."""
- return not self.block_is_mapped(block)
-
- def _get_ranges(self, start, count, whence1, whence2):
- """
- This function implements 'get_mapped_ranges()' and
- 'get_unmapped_ranges()' depending on what is passed in the 'whence1'
- and 'whence2' arguments.
- """
-
- assert whence1 != whence2
- end = start * self.block_size
- limit = end + count * self.block_size
-
- while True:
- start = _lseek(self._f_image, end, whence1)
- if start == -1 or start >= limit or start == self.image_size:
- break
-
- end = _lseek(self._f_image, start, whence2)
- if end == -1 or end == self.image_size:
- end = self.blocks_cnt * self.block_size
- if end > limit:
- end = limit
-
- start_blk = start / self.block_size
- end_blk = end / self.block_size - 1
- self._log.debug("FilemapSeek: yielding range (%d, %d)"
- % (start_blk, end_blk))
- yield (start_blk, end_blk)
-
- def get_mapped_ranges(self, start, count):
- """Refer the '_FilemapBase' class for the documentation."""
- self._log.debug("FilemapSeek: get_mapped_ranges(%d, %d(%d))"
- % (start, count, start + count - 1))
- return self._get_ranges(start, count, _SEEK_DATA, _SEEK_HOLE)
-
- def get_unmapped_ranges(self, start, count):
- """Refer the '_FilemapBase' class for the documentation."""
- self._log.debug("FilemapSeek: get_unmapped_ranges(%d, %d(%d))"
- % (start, count, start + count - 1))
- return self._get_ranges(start, count, _SEEK_HOLE, _SEEK_DATA)
-
-
-# Below goes the FIEMAP ioctl implementation, which is not very readable
-# because it deals with the rather complex FIEMAP ioctl. To understand the
-# code, you need to know the FIEMAP interface, which is documented in the
-# "Documentation/filesystems/fiemap.txt" file in the Linux kernel sources.
-
-# Format string for 'struct fiemap'
-_FIEMAP_FORMAT = "=QQLLLL"
-# sizeof(struct fiemap)
-_FIEMAP_SIZE = struct.calcsize(_FIEMAP_FORMAT)
-# Format string for 'struct fiemap_extent'
-_FIEMAP_EXTENT_FORMAT = "=QQQQQLLLL"
-# sizeof(struct fiemap_extent)
-_FIEMAP_EXTENT_SIZE = struct.calcsize(_FIEMAP_EXTENT_FORMAT)
-# The FIEMAP ioctl number
-_FIEMAP_IOCTL = 0xC020660B
-# This FIEMAP ioctl flag which instructs the kernel to sync the file before
-# reading the block map
-_FIEMAP_FLAG_SYNC = 0x00000001
-# Size of the buffer for 'struct fiemap_extent' elements which will be used
-# when invoking the FIEMAP ioctl. The larger is the buffer, the less times the
-# FIEMAP ioctl will be invoked.
-_FIEMAP_BUFFER_SIZE = 256 * 1024
-
-class FilemapFiemap(_FilemapBase):
- """
- This class provides API to the FIEMAP ioctl. Namely, it allows to iterate
- over all mapped blocks and over all holes.
-
- This class synchronizes the image file every time it invokes the FIEMAP
- ioctl in order to work-around early FIEMAP implementation kernel bugs.
- """
-
- def __init__(self, image, log=None):
- """
- Initialize a class instance. The 'image' argument is full the file
- object to operate on.
- """
-
- # Call the base class constructor first
- _FilemapBase.__init__(self, image, log)
- self._log.debug("FilemapFiemap: initializing")
-
- self._buf_size = _FIEMAP_BUFFER_SIZE
-
- # Calculate how many 'struct fiemap_extent' elements fit the buffer
- self._buf_size -= _FIEMAP_SIZE
- self._fiemap_extent_cnt = self._buf_size / _FIEMAP_EXTENT_SIZE
- assert self._fiemap_extent_cnt > 0
- self._buf_size = self._fiemap_extent_cnt * _FIEMAP_EXTENT_SIZE
- self._buf_size += _FIEMAP_SIZE
-
- # Allocate a mutable buffer for the FIEMAP ioctl
- self._buf = array.array('B', [0] * self._buf_size)
-
- # Check if the FIEMAP ioctl is supported
- self.block_is_mapped(0)
-
- def _invoke_fiemap(self, block, count):
- """
- Invoke the FIEMAP ioctl for 'count' blocks of the file starting from
- block number 'block'.
-
- The full result of the operation is stored in 'self._buf' on exit.
- Returns the unpacked 'struct fiemap' data structure in form of a python
- list (just like 'struct.upack()').
- """
-
- if self.blocks_cnt != 0 and (block < 0 or block >= self.blocks_cnt):
- raise Error("bad block number %d, should be within [0, %d]"
- % (block, self.blocks_cnt))
-
- # Initialize the 'struct fiemap' part of the buffer. We use the
- # '_FIEMAP_FLAG_SYNC' flag in order to make sure the file is
- # synchronized. The reason for this is that early FIEMAP
- # implementations had many bugs related to cached dirty data, and
- # synchronizing the file is a necessary work-around.
- struct.pack_into(_FIEMAP_FORMAT, self._buf, 0, block * self.block_size,
- count * self.block_size, _FIEMAP_FLAG_SYNC, 0,
- self._fiemap_extent_cnt, 0)
-
- try:
- fcntl.ioctl(self._f_image, _FIEMAP_IOCTL, self._buf, 1)
- except IOError as err:
- # Note, the FIEMAP ioctl is supported by the Linux kernel starting
- # from version 2.6.28 (year 2008).
- if err.errno == os.errno.EOPNOTSUPP:
- errstr = "FilemapFiemap: the FIEMAP ioctl is not supported " \
- "by the file-system"
- self._log.debug(errstr)
- raise ErrorNotSupp(errstr)
- if err.errno == os.errno.ENOTTY:
- errstr = "FilemapFiemap: the FIEMAP ioctl is not supported " \
- "by the kernel"
- self._log.debug(errstr)
- raise ErrorNotSupp(errstr)
- raise Error("the FIEMAP ioctl failed for '%s': %s"
- % (self._image_path, err))
-
- return struct.unpack(_FIEMAP_FORMAT, self._buf[:_FIEMAP_SIZE])
-
- def block_is_mapped(self, block):
- """Refer the '_FilemapBase' class for the documentation."""
- struct_fiemap = self._invoke_fiemap(block, 1)
-
- # The 3rd element of 'struct_fiemap' is the 'fm_mapped_extents' field.
- # If it contains zero, the block is not mapped, otherwise it is
- # mapped.
- result = bool(struct_fiemap[3])
- self._log.debug("FilemapFiemap: block_is_mapped(%d) returns %s"
- % (block, result))
- return result
-
- def block_is_unmapped(self, block):
- """Refer the '_FilemapBase' class for the documentation."""
- return not self.block_is_mapped(block)
-
- def _unpack_fiemap_extent(self, index):
- """
- Unpack a 'struct fiemap_extent' structure object number 'index' from
- the internal 'self._buf' buffer.
- """
-
- offset = _FIEMAP_SIZE + _FIEMAP_EXTENT_SIZE * index
- return struct.unpack(_FIEMAP_EXTENT_FORMAT,
- self._buf[offset : offset + _FIEMAP_EXTENT_SIZE])
-
- def _do_get_mapped_ranges(self, start, count):
- """
- Implements most the functionality for the 'get_mapped_ranges()'
- generator: invokes the FIEMAP ioctl, walks through the mapped extents
- and yields mapped block ranges. However, the ranges may be consecutive
- (e.g., (1, 100), (100, 200)) and 'get_mapped_ranges()' simply merges
- them.
- """
-
- block = start
- while block < start + count:
- struct_fiemap = self._invoke_fiemap(block, count)
-
- mapped_extents = struct_fiemap[3]
- if mapped_extents == 0:
- # No more mapped blocks
- return
-
- extent = 0
- while extent < mapped_extents:
- fiemap_extent = self._unpack_fiemap_extent(extent)
-
- # Start of the extent
- extent_start = fiemap_extent[0]
- # Starting block number of the extent
- extent_block = extent_start / self.block_size
- # Length of the extent
- extent_len = fiemap_extent[2]
- # Count of blocks in the extent
- extent_count = extent_len / self.block_size
-
- # Extent length and offset have to be block-aligned
- assert extent_start % self.block_size == 0
- assert extent_len % self.block_size == 0
-
- if extent_block > start + count - 1:
- return
-
- first = max(extent_block, block)
- last = min(extent_block + extent_count, start + count) - 1
- yield (first, last)
-
- extent += 1
-
- block = extent_block + extent_count
-
- def get_mapped_ranges(self, start, count):
- """Refer the '_FilemapBase' class for the documentation."""
- self._log.debug("FilemapFiemap: get_mapped_ranges(%d, %d(%d))"
- % (start, count, start + count - 1))
- iterator = self._do_get_mapped_ranges(start, count)
- first_prev, last_prev = iterator.next()
-
- for first, last in iterator:
- if last_prev == first - 1:
- last_prev = last
- else:
- self._log.debug("FilemapFiemap: yielding range (%d, %d)"
- % (first_prev, last_prev))
- yield (first_prev, last_prev)
- first_prev, last_prev = first, last
-
- self._log.debug("FilemapFiemap: yielding range (%d, %d)"
- % (first_prev, last_prev))
- yield (first_prev, last_prev)
-
- def get_unmapped_ranges(self, start, count):
- """Refer the '_FilemapBase' class for the documentation."""
- self._log.debug("FilemapFiemap: get_unmapped_ranges(%d, %d(%d))"
- % (start, count, start + count - 1))
- hole_first = start
- for first, last in self._do_get_mapped_ranges(start, count):
- if first > hole_first:
- self._log.debug("FilemapFiemap: yielding range (%d, %d)"
- % (hole_first, first - 1))
- yield (hole_first, first - 1)
-
- hole_first = last + 1
-
- if hole_first < start + count:
- self._log.debug("FilemapFiemap: yielding range (%d, %d)"
- % (hole_first, start + count - 1))
- yield (hole_first, start + count - 1)
-
-
-def filemap(image, log=None):
- """
- Create and return an instance of a Filemap class - 'FilemapFiemap' or
- 'FilemapSeek', depending on what the system we run on supports. If the
- FIEMAP ioctl is supported, an instance of the 'FilemapFiemap' class is
- returned. Otherwise, if 'SEEK_HOLE' is supported an instance of the
- 'FilemapSeek' class is returned. If none of these are supported, the
- function generates an 'Error' type exception.
- """
-
- try:
- return FilemapFiemap(image, log)
- except ErrorNotSupp:
- return FilemapSeek(image, log)
projects / tools / mic.git / commitdiff