KR20060056626A - Method of extracting file's information - Google Patents

Abstract

The present invention relates to a method of extracting file information from a device using a file allocation table (FAT) file system.

A method of extracting file information from a device using a FAT file system includes extracting name information of a file from a directory entry for the file in order to extract information of a file included in a directory to be searched. At the same time as the first process of extracting information of the extension, attribute, last modified time, last modified date, start cluster, and size of the file, and the file from which information is extracted until all the information of the files included in the directory is extracted. In addition, it characterized in that it comprises a second process for proceeding the first process for extracting information of the remaining files.

FAT, file system, directory, directory entry

Description

How to extract file information {METHOD OF EXTRACTING FILE'S INFORMATION}             

1 is a structural diagram of a directory entry;

2 is a flowchart illustrating a process of extracting file information according to a preferred embodiment of the present invention.

The present invention relates to a method of extracting file information from a device using a file system, and more particularly, to a method of extracting file information from a device using a file allocation table (FAT) file system.

The file system is software that reads and writes data in file units. Among them, the FAT file system is a file system mainly used in personal computers. The FAT file system is used not only for personal computers but also for compatibility with personal computers in digital cameras, personal digital assistants (PDAs), and portable terminals.                         

FAT file system is the information that files are stored from several clusters to several clusters based on the cluster that divides the storage media where files are stored, for example, hard disk, floppy disk, flash memory, external memory card, etc. To the device.

The FAT file system provides a directory entry containing a directory or file information. The directory entry is stored in the storage medium, and its structure is as shown in FIG.

1 is a structural diagram of a directory entry. The directory entry of FIG. 1 has a size of 32 bytes, in order of file name information in spaces of 0 to 8 bytes, file extension information in spaces of 9 to 11 bytes, attribute information of files in spaces of 11 to 12 bytes, and 12 Reserved space in ~ 22 bytes, file latest modification time information in 23-24 bytes space, latest modification date of file in 25-26 bytes space, start of file in 27-28 bytes space Cluster information, file size information is stored in a space of 29 to 32 bytes.

A method of extracting information of a file, that is, information of a file stored in a directory entry, in a device using a FAT file system configured as described above is as follows.

First, assuming that there are 1000 files included in the directory to be searched, the structure is as follows.

Directory-File 1 (Directory Entry1)                         

File 2 (Directory Entry 2)

File 3 (Directory Entry 3)

                ...

-File 1000 (directory entry 1000)

Thus, if there are 1000 files in a directory, there are also 1000 directory entries that contain file information for each file. A device using the FAT file system to extract information of files included in the directory uses functions provided by the FAT file system as described below.

Directory = opendir (directory name);

Filename = readdir (directory);

while (filename! = NULL)

{

Filename = readdir (directory);

}

When the name of the directory is received as a parameter, the opendir function searches a directory corresponding to the directory name and provides a directory entry for the searched directory and order information of the files included in the directory. A device using a FAT file system receives a directory entry for the directory and order information of files contained in the directory from the opendir function and provides the information as an argument of a function called readdir. The readdir function is a function of providing name information of files included in the directory in order one by one when receiving a directory entry for the directory and order information of the files included in the directory.

That is, when a device using a FAT file system provides an argument value provided through the opendir function to the readdir function for the first time, the readdir function provides name information of the first file among the files included in the directory. . When the device using the FAT file system provides the argument value to the readdir function, the readdir function provides name information of a second file among the files included in the directory.

In more detail, the readdir function refers to the location of the directory by identifying the starting cluster in which the directory is stored from the directory entry for the directory provided as an argument value. Accordingly, by referring to the files included in the directory, a device using the FAT file system can read the name information of the files from the directory entry for the files. Further, whenever the device using the FAT file system provides the argument value to the readdir function, the reason that the readdir function can provide the name information of the file in order is because of the value of the files included in the directory. This is because order information is provided. The speed of extracting file name information is fast because the readdir function can refer to the location of the next file through the order information of the files immediately after the single file name information is extracted. Devices using the FAT file system continue to provide the argument value to the readdir function until the readdir function extracts the name information of all the files contained in the directory and can no longer provide the name information of the file.

Next, to extract information other than the name of a file included in the directory in a device using a FAT file system, a function stat as described below is used.

Directory = opendir (directory name);

Filename = readdir (directory);

while (filename! = NULL)

{

File information = stat (filename);

Filename = readdir (directory);

}

The stat function receives the name information of the file provided through the readdir function as an argument value, searches for a file matching the name of the file, and if a file matching the name of the file is found, the name information of the searched file is retrieved. This function provides the remaining information through the directory entry of the file. The stat function compares the names of the files included in the directory with the argument values in order to search for a file matching the name of the file received as the argument value. When a file matching the argument value is found, the stat function provides the remaining information except the name information of the found file through the directory entry of the file.

The stat function compares the names of the files included in the directory with the argument values in order. If the name of the file received as the argument value is the name of a file located in the front of the directory such as files 1, 2, and 3, the comparison Short time

However, if the name of the file received as an argument is the name of a file located later in the directory, such as file 1000, the comparison time performed by the stat function becomes long. Because the stat function compares the files included in the directory with the argument values one by one in order to find the name of the file that matches the file 1000, The comparison time is long.

Therefore, in the case of extracting the information of a file of a predetermined directory in a device using a FAT file system, the more time is included in the predetermined directory, the longer the comparison time of the stat function is performed to extract the information of the file. Accordingly, a problem of slowing down the speed of extracting file information from a device using a FAT file system occurs.                         

In order to solve the above problems, there is a method of limiting the number of files that can be included in a directory, for example, a method of limiting the number of files that can be included in one directory to 100. Some digital cameras and portable terminals use such a method, but this has a problem that inconveniences users by limiting the number of files that can be stored.

Accordingly, it is an object of the present invention to provide a method for extracting file information so that a device using a FAT file system does not slow down even if a large number of files are included in a predetermined directory.

A method of extracting file information in a device using a FAT file system according to the present invention for achieving the above object is to extract information of a file included in a directory to be searched. The first process of extracting the information of the extension, the attribute, the latest modification time, the latest modification date, the start cluster, and the size of the file and extracting the name information and the information until the information of the files included in the directory are all extracted. And a second step of proceeding with the first step for extracting information of remaining files in addition to the extracted file.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

First, the characteristics of the above-described readdir function and stat function will be described. Providing the file name information in the readdir function means that the information of the file among the information of the file included in the directory entry for the file to provide the file name information Only name information is read. In addition, providing the file information in the stat function is to search for a file matching the name of the predetermined file received as an argument value and to store the remaining information except for the file name information among the information of the file included in the directory entry of the retrieved file. To read.

In a preferred embodiment of the present invention, the method that the readdir function can extract the remaining information at the same time when the readdir function extracts the file name information by using the speed of providing the file name information to a function called readdir_stat Implement and provide

A function called readdir_stat is implemented to extract file name information, file extension information, file attribute information, file latest modification time information, file latest modification date information, file start cluster information, and file size information.

Accordingly, the device using the FAT file system can receive all the information of the file from the directory entry without using the stat function. A method of extracting file information as described above will be described in detail with reference to the flowchart of FIG. 2.                     

2 is a flowchart illustrating a process of extracting file information according to a preferred embodiment of the present invention.

A device using the FAT file system provides the name of the directory as a parameter to the opendir function to obtain name information of a file included in a directory to be searched. The opendir function provided with the argument value searches a directory corresponding to the directory name and provides a directory entry for the searched directory and order information of the files included in the directory to a device using the FAT file system (S100). .

Then, the device using the FAT file system provides the readdir_stat function with a directory entry for the provided directory and order information of the files included in the directory as argument values. The readdir_stat function reads the name information of the first file from the directory entry for the files in accordance with the order information and at the same time the file extension information, the file attribute information, the latest modification time information of the file, and the latest modification date information of the file. It also reads the file's starting cluster information and file size information. Therefore, the device using the FAT file system may extract the remaining information at the same time as the name information of the file (S200).

When the information of the first file is extracted, the device using the FAT file system checks whether the readdir_stat function extracts the information of all the files included in the directory. The device using the FAT file system extracts the information of the next file by performing the step S200 until all the file information is extracted and the readdir_stat function can no longer provide the file information (S300).

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined not only by the claims but also by the equivalents of the claims.

According to the present invention as described above, even if a large number of files included in the directory, the user can achieve the convenience of use that does not feel that the speed of file search does not slow down.

In addition, even if the number of files that can be included in the directory is not limited, the file search speed is not affected.

Claims (1)

A method of extracting file information from a device using a file allocation table (FAT) file system, In order to extract information of a file included in a directory to be searched, the name information of the file is extracted from a directory entry for the file, and at the same time, an extension, an attribute, a recent modification time, and a recent time of the file are extracted. Extracting information of a modification date, a start cluster, and a size; And And a second step of proceeding with the first step of extracting information of remaining files other than the file from which information is extracted until all information of files included in the directory is extracted.

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