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Method and program for file information write processingRelated Patent Categories: Data Processing: Database And File Management Or Data Structures, File Or Database MaintenanceMethod and program for file information write processing description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060173923, Method and program for file information write processing. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-375074, filed in Dec. 12, 2004, the entire contents of which are incorporated herein by reference. FIELD OF THE INVENTION [0002] The present invention relates to a processing method for writing file information and program thereof. BACKGROUND OF THE INVENTION [0003] File access within a computer system is realized through a combination of three programs: application; file system (middleware); and device driver. Here, application refers to various application programs such as word processors and CAD software. Device driver refers to a control program which performs read/write on each area within a (nonvolatile) secondary memory, such as magnetic disks and flash memory, wherein stored contents are retained even when power is tuned off. File system (middleware), which is provided between application and device driver, performs a process for outputting instructions corresponding to the write instructions from the application to the device driver. [0004] With a file system such as this, when power supplies were unexpectedly cut off during writing data and a write failure occurs, problems frequently lie in how the information in the file relevant to the write is restored. From this relation, methods addressing write failures such as this are disclosed in many references such as Patent Reference 1. [0005] [Patent Reference 1] [0006] Japanese Patent Laid-Open Publication No. 2003-169293 "Data recorder/player, means for recording and playing data, and digital camera" DESCRIPTION OF THE RELATED ART [0007] The following are explanations of an instance where a write instruction sent from the application to the file system is a file overwrite instruction and an instance where the write instruction is a file move instruction, during file access by a computer. [0008] First, the process performed by the middleware corresponding to an overwrite instruction when the overwrite instruction is given to the middleware from the application is explained. [0009] FIG. 1 is a diagram showing the data configuration of the file system. [0010] As shown in FIG. 1, the file system comprises three areas: a boot sector; file allocation table (FAT); and an actual data area. [0011] Here, information regarding the entire file system, such as the file system capacity, the size of the cluster which is the processing unit of the actual data area, and the position of the root directory within the actual data area, are described in the boot sector. In addition, pointer information which indicates which cluster a cluster is connected to is stored in each entry of the FAT corresponding to individual clusters within the actual data area. If the cluster has no connection destination, "End" is set in this pointer information. If the cluster is freed, "NULL" is set in this pointer information (shown as blank in the diagram). In other words, data retained within the clusters corresponding to entries within FAT wherein a pointer value other than "NULL" is set is data which has meaning. [0012] Furthermore, the actual data area that is used is separated into (processing) units called clusters, and actual information regarding files and directories are stored therein. In FIG. 1, for simplicity, actual data area is divided into 16 clusters, and these clusters have head addresses of hexadecimal numerals 0 to 15, in sequence, with the progression from the upper-right to the lower-left; in other words, "0x0", "0x1", "0x2", "0x3", "0x4", "0x5", "0x6", "0x7", "0x8", "0x9", "0xA", "0xB", "0xC", "0xD", "0xE", and "0xF". [0013] For example, in FIG. 1, it is understood, by referring to the boot sector, that the root director of the actual data area corresponds to the "0x0" cluster, and from the contents of this "0x0" cluster, it is indicated that a file (File1), of which the data length (Length)=5 and the head actual data (Data1) is in the "0x1" cluster, exists in this root directory as a directory entry. [0014] Since information regarding the interconnection of clusters within the actual data area is stored in the FAT, in FIG. 1, it is understood, by referring to the FAT, that data (Data 2) of the "0x2" cluster exists as the subsequent data of data (Data 1) of the "0x1" cluster, data (Data 3) of the "0xB" cluster exists as the subsequent data of data (Data 2) of the "0x2" cluster, data (Data 4) of the "0xE" cluster exists as the subsequent data of data (Data 3) of the "0xB" cluster, and data (Data 5) of the "0x5" cluster exists as the subsequent data of data (Data 4) of the "0xE" cluster. In addition, since the FAT entry corresponding to this "0x5" cluster is "End", it is understood that the data in this file (File 1) ends with data (Data 5) of this "0x5" cluster. Here, the fact that directory entry File1 (of the root directory) is configured so that Data 1, Data 2, Data 3, Data 4, and Data 5 are connected in sequence is represented as is shown in the bottom row of FIG. 1. [0015] Overwrite instruction is given in regards to File1, such as this, from the application which output this File 1. FIG. 2 is a diagram showing the state of the file before overwrite instruction is made. [0016] File system (middleware) specifies the (one or plural) cluster(s) within the secondary memory (actual data area) which is the target of write, implementing information regarding the starting location and the length of the overwrite comprised in the file overwrite instruction from the application. Here, clusters corresponding to Data 2, Data 3, and Data 4 are considered clusters which have been specified as such. [0017] In other words, first, the content of the cluster corresponding to Data 2 is overwritten as shown in FIG. 3; next, the content of the cluster corresponding to Data 3 is overwritten as shown in FIG. 4; and furthermore, the content of the cluster corresponding to Data 4 is overwritten as shown in FIG. 5. [0018] FIG. 6 is a flowchart of a conventional overwrite process. [0019] In FIG. 6, first, data overwrite (write) process is performed on one or plural cluster(s) within the actual data area specified as overwrite target in Step S101. In the subsequent step S102, file information, for example last update time information, is changed (updated). [0020] However, if file overwrite is performed by a procedure such as this, when, for example, a write failure such as power supply interruption occurs during the first, second, and third write, such as that shown in FIG. 3, FIG. 4, or FIG. 5, the data of the cluster which is being written, in other words the cluster corresponding to Data 2, Data 3, or Data 4, is stored to the secondary memory in an incomplete state. This means, the period from the start of overwrite of the cluster corresponding to Data 2 in FIG. 3 until before the completion of overwrite of the cluster corresponding to Data 4 in FIG. 5 is a period wherein incomplete data will be left within the secondary memory if a power supply interruption or the like occurs. In other words, it is a period wherein there is risk of data damage. Continue reading about Method and program for file information write processing... Full patent description for Method and program for file information write processing Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and program for file information write processing patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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