JPS6369066A - Data correcting system on unrewritable medium - Google Patents

Abstract

PURPOSE:To control rewritably by adding a correcting block to an unwritten area and recording a writing position. CONSTITUTION:An input/output request program 2 successively requests an input output control means 4 to input the data record in a data file 1. The means 4 obtains a block position to be inputted from the file 1 while it inputs a block position data from an index file 3 to an index buffer 6. In accordance with this, the data are inputted to a data buffer 5 and a data record requested from the inside of the block is delivered to a program 2. At the time of the necessity, the inputted data record is corrected, delivered to the means 4 and requested to be replaced to an original record. The means 4 replaces the original record in the buffer 5 to the record after the correction, outputs newly the block to the unwritten area in the file 1, changes the position data of the corresponding block in the buffer 6 to he new data and outputs them to the index file 3. Thus, by recording the writing position, the re-writing can be executed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention accesses a file on a non-rewritable medium that cannot write data to the same part again after writing data once, and modifies the data. Regarding the method of

[Conventional technology]

Conventionally, data correction has been carried out by making it impossible to modify the contents of a file on a non-rewritable medium, or by creating a new file and copying the data therein in a format that includes the modified data.

[Problem to be solved by the invention] As mentioned above, if data cannot be modified, only unmodified data can be written on a non-rewritable medium, and great care must be taken when using it. It was narrow. Furthermore, the method of creating a new file and copying it there does not pose much of a problem if the file size is small. but,
If the file size is large, a file of the same size is required even if a part of the image is corrected, so there is a drawback that there is a large amount of waste.

[Means for solving problems]

The present invention provides a data file on a non-rewritable medium in which data cannot be written to the same part again after data is written therein, an input/output request program that requests input/output to the data file, and an input/output request program that requests input/output to the data file. an index file on a rewritable medium for managing block positions written in a data file; an input/output control means for controlling input/output to the data file and the index file; The input/output request program first records data in the data file. In the case where the input/output control means receives a request from the input/output request program, it writes the records as a block on the data buffer to the data file, and also writes the block position on the data file via the index buffer. iK is stored in the index file, and when the input/output request program sequentially reads data records in the data file, the input/output control means that receives a request from the input/output request log 2 executes the index file. input block position data from the data file into the index buffer to determine the block position to be input in the data file, input the block from the data file to the data buffer, and pass the data record to the input/output request program; When the input/output request program requests modification of an input data record, the input/output control means that received the request from the input/output request program replaces the original data record and the modified data record on the data buffer. After that, the block on the data buffer is written as a new block in the rear unwritten part of the data file, and the block position on the index buffer 7 is changed to a new block position and written to the index file. The present invention is characterized in that it enables correct input from the corrected block for subsequent data record input requests.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

Referring to FIG. 1, one embodiment of the present invention uses an original disk as a non-rewritable medium and a magnetic disk as a rewritable medium.

In addition to magnetic disks, floppy disks, electronic disks, magnetic tapes, etc. can also be used as rewritable media. One embodiment of the present invention includes a data file 1 on a source disk, an input/output request program 2 that requests input/output to this data file 1, an index file 3 on a magnetic disk, an input/output control means 4, and the data file 10. It is composed of a data buffer 5 used for inputting and outputting, and an index buffer 6 used for inputting and outputting the index file 30.

First, when the input/output request program 2 creates the data file 1, the input/output control means sets the area of the data file 1, the area of the index file 3, and the block size of the data file l secured in advance before the actual input/output execution. 4
Notify. The input/output control means 4 secures the storage area of the data buffer 5 based on the notified block size, and also secures the storage area of the index buffer 6 of a certain size. Furthermore, program 2 calculates the maximum number of blocks that can be stored in data file 1 by dividing the size of data file l by the block size, and determines whether this maximum number of block position data can be stored in index file 3. Determine whether or not.

If it cannot be stored, index file 3 is expanded.

The input/output request program 2 then sequentially passes the data records to be input to the data file IK to the input/output control means 4. The input/output control means 4 accumulates the passed data records in the data buffer 5, and outputs them to the data file 1 as a block when the data buffer 5 is full. Further, the input/output control means 4 stores the block position of the output block in the data file 1 as data in the index buffer 6, and outputs it to the index file 2 when the index buffer 6 is also full.

Next, data record input from data file 1 and data record modification will be explained. The input/output request program 2 sequentially requests the input/output control means 4 to input data records in the data file 1. Input/output control means 4
inputs the block position data from the index file 3 into the index buffer 6 to find the block position to be input from the data file 1. A block is input from the data file 1 to the data buffer 5 according to the obtained block position, and the requested data record from within the block is passed to the similar input/output request program 2. Then, the input/output request program 2 refers to the input data record, modifies the data record if necessary, and passes it to the input/output control means 4.

Request replacement with the original data record.

The input/output control means 4 replaces the original data record in the data buffer with the modified data record, outputs a new block in the data buffer to an unwritten portion in the data file 1, and outputs a new block in the index buffer 6. The position data of the corresponding block is also changed to new data and output to the index file 3. .

Referring to FIG. 2, the first three block position data from the index file 3 are input into the index buffer 6. Block 2 is input from data file 1 to data buffer 5 based on position data A2 of block 2, and the data record is passed from there to input/output request program 2.

Referring to FIG. 3, the input/output request program 2 modifies the contents of a data record and requests its replacement as a data record. In this case, first, the data record R in the data buffer 5 is replaced with the data record 几' and output as a new block 2 to the unwritten block position An. Furthermore, index buffer 6
The location A2 of block 2 in the index file 3 is changed to An, and then written to the index file 3.

Next, each process of the input/output control means will be described in detail with reference to FIGS. 4 to 7.

Referring to FIG. 4, in the preparation process before actual input/output, the input/output request program 2 sends data to the data file 1 area, the index file 3 area, and the block size of the data file 1 to the input/output control means 4. will be notified. Upon receiving the notification, the input/output control means 4 performs steps 401 and 40.
In step 2, storage areas for the data buffer 5 and index buffer 6 are secured, and in step 403, the maximum number of blocks that can be stored in the data file 1 is calculated. Step 404
In step 405, it is determined whether the size of the index file 3 is sufficient, and if it is insufficient, it is expanded.Next, referring to FIG. explain. When an output request is received from the input/output request program 2, first step 5 is performed.
At step 01, it is determined whether the data record to be output can be stored in the data buffer 5 or not. If it is determined that the data record can be stored, the data record is stored in the data buffer 5 in step 506, and the process ends. If the data buffer 5 is full and cannot store data, steps 502 to 506 are executed. In step 502, data in the data buffer 5 is output as a block to the data file 1. In step 503, it is determined whether the output block position can be stored in the index buffer,
If A is determined to be able to be stored, the data record of the outgoing request is stored in step 505. If it cannot be stored, the contents of the index buffer are output to the index file in step 504, and then the data record of the output request is stored in step 505.

Next, the process of inputting data records from the data file 1 will be described in detail with reference to FIG.

First, when an input request is received from the input/output request program 2, it is determined in step 601 whether or not a target data record exists in the data buffer 5. If it is determined that the data record exists, the target data record is extracted in step 605.

If it does not exist, in order to input the next block, it is determined whether or not the position of the next block exists by referring to the index buffer 6. If not, step 60
3, block position data is input from the index file 3. In step 604, the next block is input from data file 1 based on the next block position input in step 603. Thereafter, in step 605, the target data record is retrieved.

Next, with reference to FIG. 7, a modification process for modifying a data record will be described in detail. Receive modified data record from input/output request program 2, step 701
The unmodified data record in the data buffer 5 is replaced with the modified data record)'. At step 702, the block in the data buffer 5 is output to the unwritten portion of the data file 1. In step 703, the block position in the index buffer 6 is changed to the block position output in step 702, and in step 704, the contents of the index buffer 6 are output to the index file 3.

In the above embodiment, the number of blocks that can be stored in the data buffer 5 and index buffer 6 is one, but it is possible to store a plurality of blocks. Also, index files always exist on a one-to-one basis with data files, but by assigning a block number to each block), when data file 1 is opened, data file l is read once and the block is Correlate numbers and block positions, and if a block with the same block number is input, register the newly read block as the latest block, create index 7 file 3, and delete it when data file 1 is closed. It is also possible to do so.

〔Effect of the invention〕

As explained above, the present invention can write a modified block by adding it to an unwritten area on a non-rewritable medium, and record the written position on a rewritable medium, which requires minimal resources. This has the effect of overcoming the disadvantages of non-rewritable media by controlling the amount of media as if they were rewritable, and expanding the scope of their use.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a state diagram showing the process up to data record input, Fig. 3 is a state diagram showing data record modification, and Figs. 4 to 7 are state diagrams showing data record input. FIG. 3 is a diagram showing each processing step of the output control means. 1 to 7, 1... a data file on a non-rewritable medium, 2... an input/output request program, 3... an index file on a rewritable medium, 4...
...I/O control means, 5...Data buffer, 6...
・Index buffer, 401, 402, 403, 404°4
05... Each step of the preparation process, 501, 502
゜503.504,505,506...Each step of output processing, 601,602,603,604,605.
...Each step of input processing, 701, 702, 703,
704... Correction (-- Fig. 5, Fig. 6, Fig. 7)

Claims (1)

[Scope of Claims] An input/output request program means for requesting data input/output to a data file on a non-rewritable medium in which data cannot be written in the same area again after data has been written, and said data file. a data storage means for overwriting and storing modified data on data exchanged between and already stored; a writing means for writing the modified data of the data storage means into an unwritten portion of the data file; storage position changing means for changing the storage position of the data file of the data before being overwritten by the writing means to the storage position of the data file written by the writing means. data modification method.