1. Field of the Invention
The present invention relates to apparatus and operation methods of file system, and in particular relates to methods and electronic devices for modifying the file header.
2. Description of the Related Art
When the computer stores files, the disk driver needs to record files information (name, location, size, etc.) into the file allocation table (FAT). The computer also needs to first find locations of files from the FAT when retrieving or storing files, such that the desired files can be successfully found. The FAT will record which clusters have been used, which clusters have not been used, and cluster locations in which the files are stored. The cluster is the basic unit of files storage, one cluster consists of many sectors, and the cluster is the smallest unit of storage space that the operating system can allocate to a file. If a file's size is smaller than one cluster, the file will occupy one cluster. If a file's size exceeds the amount that can be contained in one cluster, the file will also occupy an integer number of clusters. It is noted that a file may be stored in discontiguous clusters.
Conventionally, the method for modifying the file header is to copy the original data following the old header to the end of the new header. However, such method may result in a large amount of data movement, causing degraded performance accordingly.