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Compressed-file recovery method of APFS file system and storage medium

A technology for compressing files and restoring methods, applied in the direction of file systems, file/folder operations, file access structures, etc., and can solve problems such as restoration failures

Active Publication Date: 2018-06-01
XIAMEN MEIYA PICO INFORMATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method can only handle uncompressed data, and the compressed data cannot recognize the signature information because the data is compressed, which will cause the recovery to fail

Method used

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  • Compressed-file recovery method of APFS file system and storage medium
  • Compressed-file recovery method of APFS file system and storage medium

Examples

Experimental program
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Embodiment 1

[0056] Please refer to figure 2 , the first embodiment of the present invention is: a compressed file recovery method of the APFS file system. Before explaining the steps of this method, the APFS file system is introduced first.

[0057]The minimum storage unit of the APFS file system is a block, and the size of a block is 4096 bytes. Each block of non-file data blocks begins with a 32-byte block header followed by the corresponding block data. The block header mainly consists of four parts, including the block check value (blockchecksum, 8 bytes, using Fletcher's checksum verification algorithm), block ID (blockid, 8 bytes), block version (blockversion, 8 bytes) and block type (blocktype, 2 bytes). According to different block types, the content of the block data storage identifier has different meanings. The APFS file system mainly has the following types of blocks: container blocks, file information node blocks, space management blocks, allocation information blocks, B...

Embodiment 2

[0094] This embodiment is a computer-readable storage medium corresponding to the above-mentioned embodiment, and a computer program is stored thereon, and the program implements the following steps when executed by a processor:

[0095] Acquire a free block in the free space in turn;

[0096] If the one free block is a file information node block, and the one free block contains compressed data, read and decompress the compressed data;

[0097] Judging whether the free block is a first type of data block, the first type of data block includes an index table and a compressed block, if so, according to the value of each index in the index table, calculate the value of the free block. the length of each compressed block;

[0098] According to the index table and the length of each compressed block, read and decompress the compressed data of each compressed block;

[0099] Determine whether the free block is a second type of data block, the second type of data block includes a ...

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Abstract

The invention discloses a compressed-file recovery method of an APFS file system and a storage medium. The method includes: sequentially acquiring an idle block in idle space; reading and decompressing compressed data if the idle block is a file information node block and the compressed data exist; judging whether the idle block is a first-type data block, and if yes, calculating and obtaining length of each compressed block according to a value of each index in an index table, wherein the first-type data block includes the index table and the compressed blocks; reading and decompressing compressed data of each compressed block according to the index table and the length of each compressed block; and judging whether the idle block is a second-type data block, and if yes, reading and decompressing compressed data of each compressed block according to a value of each index in an index table, wherein the second-type data block includes a compression header, the index table and the compressed blocks. The method can completely recover deleted compressed data in a case where the compressed data are not overwritten.

Description

technical field [0001] The invention relates to the technical field of data recovery, in particular to a compressed file recovery method and storage medium of an APFS file system. Background technique [0002] With the continuous development of cutting-edge technology, the architecture of Apple's file system HFS+ can no longer meet the existing needs. As Apple's latest file system, the APFS file system has been gradually applied to new operating systems of various Apple products due to its high reliability and fast file processing speed. Forensics of Apple system data has always been the focus of the industry, and the launch of new APFS files has brought new challenges to Apple system data forensics. Especially the data compression function of the APFS file system, if the file with the compression attribute is deleted and the index is lost, the traditional recovery method will be invalid, and the data forensics will not be able to proceed in depth. [0003] Currently, for ...

Claims

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Application Information

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IPC IPC(8): G06F17/30
CPCG06F16/13G06F16/16
Inventor 沈长达申强吴少华傅婉莲
Owner XIAMEN MEIYA PICO INFORMATION
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