Method and device for operating Sparse-format mirror image document

Abstract

The invention provides a method and a device for operating a Sparse-format mirror image document. The method includes: analyzing the Sparse-format mirror image document, and creating a chunk index table for indexing every block in the Sparse-format mirror image document; determining the position of a document in an Ext4-format file and the serial number of a block of catalogue information when the Sparse-format mirror image file is converted into the Ext4 file, determining an address of the block with the serial number according to the chunk index table, and reading the position of the file and the catalogue information; calling an Ext4 file system operation module to determine the number of the block in which the file needing to be operated is positioned according to the read position of the file and the catalogue information, determining the address of the block with the number according to the chunk index table, and operating content in the corresponding address. The method and the device for operating the Sparse-format mirror image document have the advantages that no format conversion is needed, and file operation can be achieved in a quick and lossless manner.

Description

technical field [0001] The invention relates to the technical field of computer file systems, in particular to a method and device for operating image files in Sparse format. Background technique [0002] Ext4 is the file system format of the Linux system. For a file with discontinuous storage locations, the unoccupied disk space is "empty", but for the file system of the Ext4 format, these locations are filled with "0", and in During the transmission of the file, the data "0" filled in these positions is read out and transmitted. [0003] The file system in Sparse format is a variant of the file system in Ext4 format. The disk format of the file system in Sparse format is as follows: figure 1 shown. For the situation where space is allocated for the file system but not used, the Sparse file can make more efficient use of the file system space. It uses some short metadata to describe the "empty" disk space to reduce the disk size. Only when " Only when real file data is w...

AI Technical Summary

Problems solved by technology

Based on these differences, after the file in Ext4 format on Linux is decomposed to Windows, the symbolic link will not correspond to the original file attribute when it is made into the file attribute of Ext4 format. As a result, it cannot be mounted or the file cannot be identify

[0011] 2) The actual application scenario is to modify or replace one or several files in the image. Sometimes the file size does not change, but the above process is for the entire image file in sparse format, and one of the file entries cannot be edited separately. Inefficient and time-consuming

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