157 lines
4.8 KiB
Python
157 lines
4.8 KiB
Python
#!/usr/bin/python
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# -*- coding: utf-8 -*-
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#
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# Copyright 2013 The Plaso Project Authors.
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# Please see the AUTHORS file for details on individual authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""The range list data type."""
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class Range(object):
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"""Class that implements a range object."""
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def __init__(self, range_offset, range_size):
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"""Initializes the range object.
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Args:
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range_offset: the range offset.
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range_size: the range size.
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Raises:
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ValueError: if the range offset or range size is not valid.
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"""
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if range_offset < 0:
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raise ValueError(u'Invalid range offset value.')
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if range_size < 0:
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raise ValueError(u'Invalid range size value.')
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super(Range, self).__init__()
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self.start_offset = range_offset
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self.size = range_size
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self.end_offset = range_offset + range_size
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class RangeList(object):
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"""Class that implements a range list object."""
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def __init__(self):
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"""Initializes the range list object."""
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super(RangeList, self).__init__()
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self.ranges = []
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@property
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def number_of_ranges(self):
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"""The number of ranges."""
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return len(self.ranges)
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def GetSpanningRange(self):
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"""Retrieves the range spanning the entire range list."""
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if self.number_of_ranges == 0:
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return
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first_range = self.ranges[0]
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last_range = self.ranges[-1]
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range_size = last_range.end_offset - first_range.start_offset
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return Range(first_range.start_offset, range_size)
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def Insert(self, range_offset, range_size):
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"""Inserts the range defined by the offset and size in the list.
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Note that overlapping ranges will be merged.
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Args:
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range_offset: the range offset.
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range_size: the range size.
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Raises:
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RuntimeError: if the range cannot be inserted.
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ValueError: if the range offset or range size is not valid.
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"""
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if range_offset < 0:
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raise ValueError(u'Invalid range offset value.')
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if range_size < 0:
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raise ValueError(u'Invalid range size value.')
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insert_index = None
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merge_index = None
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number_of_range_objects = len(self.ranges)
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range_end_offset = range_offset + range_size
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if number_of_range_objects == 0:
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insert_index = 0
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else:
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range_object_index = 0
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for range_object in self.ranges:
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# Ignore negative ranges.
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if range_object.start_offset < 0:
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range_object_index += 1
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continue
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# Insert the range before an existing one.
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if range_end_offset < range_object.start_offset:
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insert_index = range_object_index
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break
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# Ignore the range since the existing one overlaps it.
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if (range_offset >= range_object.start_offset and
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range_end_offset <= range_object.end_offset):
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break
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# Merge the range since it overlaps the existing one at the end.
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if (range_offset >= range_object.start_offset and
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range_offset <= range_object.end_offset):
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merge_index = range_object_index
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break
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# Merge the range since it overlaps the existing one at the start.
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if (range_end_offset >= range_object.start_offset and
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range_end_offset <= range_object.end_offset):
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merge_index = range_object_index
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break
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# Merge the range since it overlaps the existing one.
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if (range_offset <= range_object.start_offset and
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range_end_offset >= range_object.end_offset):
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merge_index = range_object_index
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break
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range_object_index += 1
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# Insert the range after the last one.
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if range_object_index >= number_of_range_objects:
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insert_index = number_of_range_objects
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if insert_index is not None and merge_index is not None:
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raise RuntimeError(
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u'Unable to insert the range both insert and merge specified.')
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if insert_index is not None:
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self.ranges.insert(insert_index, Range(range_offset, range_size))
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elif merge_index is not None:
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range_object = self.ranges[merge_index]
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if range_offset < range_object.start_offset:
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range_object.size += range_object.start_offset - range_offset
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range_object.start_offset = range_offset
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if range_end_offset > range_object.end_offset:
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range_object.size += range_end_offset - range_object.end_offset
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range_object.end_offset = range_end_offset
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