Method for inhibiting an executable program in a disk operating system by replacing the program with an unexecutable program
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to computer software for use with a disk operating system, and more particularly to a program for inhibiting use of executable programs in a disk operating system. 
     Executable programs are programs in the disk operating system (DOS) loaded in a computer and are initiated with external commands by the computer operator. In Microsoft™ or IBM™ DOS, these programs are identified by discrete filenames with extensions COM, EXE and BAT. Programs with extensions COM and EXE, take precedence in execution over the same filename with a BAT extension. Two such programs are FORMAT.COM or FORMAT.EXE for initializing a new, unused disk, and DISKCOPY.COM or DISKCOPY.EXE for copying everything from one disk to another. 
     There are times, however, when it is desired to prevent such executable programs from being used. For instance, before a new or blank floppy or disk can receive and store information in binary form, it must be initialized or formatted with special markers so that when an executive or operating system reads or writes a file to the disk, it will know on which sector and track the file is written. Formatting also sets up directories containing file location information and checks the disk for defects. Once the disk is formatted, information can be stored on it as often as desired without reformatting. To prevent a user from writing over previously recorded information, the sleeve which contains the floppy or disk usually has a small rectangular notch or window on one side. If the notch or window is covered when inserted in a disk drive, the computer prevents information from being written on the disks. Most master distribution disk for software products have no notch and are therefore permanently write-protected. However, write-protection will not protect against formatting. Formatting will permanently wipe off the entire contents of any previously created operating systems and recorded information on the disk. Therefore, a user must always be consciously aware of the consequences of formatting any disk media, particularly a fixed disk, and be absolutely certain it contains no files which need to be retained. 
     While the consequences of accidentally or maliciously executing a formatting program are especially severe, other programs are similarly vulnerable. For instance, there is no means within a DOS for preventing a user from executing the external command DISKCOPY and making an unauthorized copy of confidential information recorded on another disk such as the fixed or hard disk of a computer. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a method for inhibiting use of an executable computer program recorded in memory. 
     Another object is to provide a method for limiting access to executable programs recorded on a disk operating system of a computer. 
     Still another object is to provide a method for temporarily removing an executable program file from a disk operating system. 
     A further object is to provide a method for preventing accidental or malicious destruction of information stored in a computer system. 
     Another object is to provide a method for preventing reproduction of confidential or proprietary programs and other recorded information on other disks. 
     A still further object is to provide a computer program which is stored on a separate disk for controlling the use of executable programs, which can be kept under supervisory custody and control, which can be used on only one computer at a time, and which is easy and economical to use. 
     Briefly, these objects and other aspects of the invention are carried out by a computer program comprising a series of executable batch processes filed on a separate software product, hereinafter referred to as a distribution disk. One of the processes, which is unconditionally ineffective for performing the functions of a specified executable program, is substituted for the executable program in the computer&#39;s disk operating system. With the distribution disk placed in an external drive selected as default, the user enters an external command INSTALL, and the substitute process file on the distribution disk and the executable program file in the computer&#39;s DOS are interchanged. The substitute file is renamed in the DOS with the same filename as the executable program but with a .BAT extension, and the distribution disk is removed from the computer. If the user now attempts, accidentally or intentionally, to initiate the program in the executable file, the ineffective substitute process is executed instead. The substitute process file can be removed by reinserting the distribution disk back into the default drive and executing an external command REMOVE. A batch routine then proceeds to find the substitute process file in the DOS and exchanges it for the executable file which was temporarily taken from the computer and stored in the distribution disk. 
     In an alternate method according to the invention, the substitute process is conditionally ineffective for operating an executable DOS program in a computer having multiple drives. The substitute process requires the user to choose, to the exclusion of at least one designated drive, a drive on which the executable DOS program can be carried out. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of these and other objects and aspects of the invention, reference is made to the following more detailed description taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a generalized flow chart of a computer program according to the invention for inhibiting the formatting of a disk; 
     FIG. 2 is a flow chart of one embodiment of an inhibition process in the computer program of FIG. 1 for unconditionally preventing formatting a disk; 
     FIGS. 3A and 3B are flow charts of an interception process for the inhibition process of FIG. 2; 
     FIG. 4 is a flow chart of a routine in the interception process of FIG. 3B for installing the inhibition process of FIG. 2; 
     FIGS. 5A and 5B are flow charts of a restoration process for the inhibition process of FIG. 2; 
     FIG. 6 is a flow chart of a routine in the restoration process of FIG. 5B for removing the inhibition process of FIG. 2; 
     FIG. 7 is a flow chart of another embodiment of an inhibition process in the computer program of FIG. 1 for conditionally preventing formatting of a disk; 
     FIG. 8 is a flow chart of a routine in the interception process of FIG. 3B for installing the inhibition process of FIG. 7; and 
     FIG. 9 is a flow chart of a routine in the restoration process of FIG. 5B for removing the inhibition process of FIG. 7. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Although the invention is applicable to any executable program initiated by an external command, one of its most useful applications is for the prevention or inhibition of formatting of floppy disks, diskettes or the hard disk in a computer. For this reason, the invention will be related to this application, but of course it is equally applicable to other executable programs. 
     The program for inhibiting formatting of disk media according to the invention is primarily implemented by a general purpose digital computer serving as the host and executed in accordance with internal and external DOS commands such as IBM™ PC-DOS, Version 3.30. Referring now to FIG. 1, the complete inhibiting program consists of three processes, interception 7, inhibition 8, and restoration 9, executed in the order illustrated by interaction of the user when external commands INSTALL, FORMAT and REMOVE, respectively, are entered into the computer. The processes are carried out by a series of batch files stored on an external distribution disk. When called, these files are loaded into the computer primary memory and executed. The interception process 7 substitutes a file containing the inhibition process 8 on the distribution disk, which is ineffective for formatting, for the file containing the formatting program in the DOS of the computer; and, at the user&#39;s command, completely restores the formatting program file to the DOS with the inhibition process file returned to the distribution disk. 
     The embodiment of the inhibition process 8 in FIG. 2, stored on an external distribution disk, such as a 3.5 inch diskette, under a filename TRANSFER.EXE, is started when the file is on the command path and the command FORMAT is entered at block 10. Appendix A hereto is a source code listing in PC-DOS commands of the routines for implementing the unconditional inhibiting program in a computer, such as an IBM™ PS/2 Model 30 or functional equivalent, having an external drive A: and a fixed or hard drive C:. However, as will become apparent hereinafter, the program is also applicable to computers having multiple external drives, e.g. A: and B:. Block 11 turns off all messages, block 12 clears the CRT screen, and block 13 displays a &#34;failure&#34; message (FORMAT PROTECTION MUST BE REMOVED IN ORDER TO FORMAT DISK MEDIA), and the process ends at block 14. Process 8, however, is not operational until it is installed in the computer in place of the DOS formatting process. To install process 8, an external disk drive, appropriate for the distribution disk on which the substitute inhibition program file is recorded and designated TRANSFER.EXE, is selected as the default drive. In the illustrated embodiment the computer has a 3.5 inch disk drive A: and the DOS is installed on the fixed disk drive C: within either the root directory or DOS subdirectory. The distribution disk is inserted in drive A:, and designated default by typing &#34;A:&#34; and pressing the RETURN or ENTER key. When the &#34;A:&gt;&#34; prompt appears on the screen, the file for the inhibiting process 8 is ready to be installed. 
     Referring now to FIG. 3A, the user starts the interception process 7 at block 20 with the external command INSTALL. Block 21 turns off all messages, and block 22 provides an interception message (INSTALL PROGRAM IN OPERATION--PLEASE WAIT) indicating interception is in process. Block 23 provides a time delay for the user to read the message. A routine for executing the time delay is disclosed at page 1134, PC Magazine DOS Power Tools, Paul Somerson, Executive Editor, PC Magazine; Bantam Books, Inc. 1988. Block 24 automatically checks whether the file for the substitute inhibition process 8 with the filename TRANSFER.EXE is on the distribution disk. If it does not exist, it would indicate that the file has already been transferred to the fixed disk, and block 25 would present a &#34;failure&#34; message (FORMAT PROTECTION ALREADY INSTALLED), and the program would end at block 26. If the TRANSFER.EXE file is found in the distribution disk, block 27 clears the screen of all messages, and block 28 may display any copyright and warning notices, and a message (PRESS CTRL-C TO ABORT--ANY OTHER KEY TO CONTINUE) offering the user the option to continue or stop the program. Block 29 suspends the program until a choice is made. To stop the program, the DOS command (CTRL-C or CTRL-BREAK) is entered. If the user presses any key to proceed with interception, block 30 defines all the file paths (FORMAT.COM and FORMAT.EXE) which are to be searched in the fixed disk&#39;s root directory (C: ) and DOS subdirectory (C: DOS ), and the installing routines to be used in the interception process 7. 
     If there are two external drives A: and B: in the computer, block 31 would determine and record, by a FLOPPY.COM routine, Appendix B, the drive in which the distribution disk had been placed. Block 32, FIG. 3B, prevents the inhibition process 8 from being installed from the hard or fixed drive. In this event, block 32a displays a &#34;failure&#34; message (NO EXTERNAL DRIVE SELECTED--PROGRAM ABORTED), and the process ends. 
     A batch loop subroutine, executed in block 33 by a conventional loop program such as disclosed at page 1036, PC Magazine DOS Power Tools, supra, checks at block 34 whether or not the executable file (FORMAT) is in one of the search paths defined in block 30. If not found, block 35 redefines the search path for the next search and block 36 determines if the search is completed. If not completed, block 36 recycles the search to block 34. If there are no more search paths, block 37 presents a &#34;failure&#34; message (CANNOT LOCATE FORMAT PROGRAM, INSTALLATION OF FORMAT PROTECTION ABORTED), block 38 sets the drive determined in block 21 back to the original distribution disk drive, and the program ends. 
     If the program is found in a selected search path, block 39 executes an install routine. Referring to FIG. 4, block 40 copies the file of the substitute inhibition process 8 (TRANSFER.EXE) from the distribution disk to the fixed disk, and block 41 copies a location marker PLACE.XXX in the DOS directory and renames it as an executable file PLACE.COM or PLACE.EXE, as appropriate. This will inform the computer during the restoration process 9 where to replace the DOS formatting file on the fixed disk. Block 42 erases the file of the inhibition process 8 from the distribution disk, and block 43 changes the default from drive A: to drive C:. Blocks 44 and 45, respectively, transfers the DOS formatting file (FORMAT.COM or FORMAT.EXE) on the fixed disk to the distribution disk and renames it FORMAT.XXX, and block 46 renames the inhibition process 8 from TRANSFER.EXE to FORMAT.BAT. 
     This completes installation of the inhibition process 8. Therefore, block 47 presents a message to that effect (FORMAT PROTECTION INSTALLED--FORMAT COMMAND LOCKED), and block 48, like block 38, sets the drive back to the original installation drive. As described above, when a user enters the command FORMAT, the substitute process is executed, which is ineffective for formatting, and displays the &#34;failure&#34; message of block 13 (FIG. 2). 
     The restoration process 9 is essentially the reverse of the interception process 7. The file for the inhibition process 8 with the filename FORMAT.BAT is returned to the distribution disk, and the DOS formatting program with the filename FORMAT.XXX is returned to the DOS directory with the extension changed back to a .COM or .EXE. In order to restore the DOS formatting program file to the computer, it is necessary to re-insert the distribution disk in an external drive and execute restoration process 9. Referring to FIG. 5A, the process is started at block 50 with the external command REMOVE. Block 51 turns off all messages from the batch file program, and block 52 automatically determines whether the inhibition process 8 file TRANSFER.EXE is on the distribution disk. If present, that would indicate the inhibition process 8 had not been installed and block 53 would present a &#34;failure&#34; message (FORMAT PROTECTION NOT INSTALLED--PROGRAM ABORTED) and the program ends. On the other hand, if the inhibition process 8 file is not found on the distribution disk, block 55 presents a restoration message (FORMAT PROTECTION REMOVAL IN PROGRESS--PLEASE WAIT). Block 56 then defines the search paths and files for the place marker (PLACE.COM or PLACE.EXE) in the fixed disk&#39;s root directory or DOS subdirectory. In the event there are two external drives, block 57 determines and records, by the routine FLOPPY.COM, Appendix B, the drive in which the distribution disk has been placed, and block 58 determines whether or not restoration process 9 is in the fixed drive. If it is, the restoration process 9 is ended with a message at block 58a (NO EXTERNAL DRIVE SELECTED--PROGRAM ABORTED). If the place marker is not on the fixed drive, block 59 executes a batch loop routine, such as disclosed at page 1036, PC Magazine DOS Power Tools, supra, in search of one of the paths (C: PLACE:COM) defined in block 56. As the search proceeds, block 60 determines whether or not the program to be removed was found on search. If not, block 61 redefines the search criteria and block 62 causes the search to repeat for another defined path and file. If no file is found, block 63 displays a &#34;failure&#34; message (CANNOT LOCATE FORMAT PROGRAM--REMOVAL OF FORMAT PROTECTION ABORTED). The drive is then set at block 64 to the original distribution disk drive and the program ends. 
     If block 60 indicates the file (PLACE.COM or PLACE.EXE) is in one of the selected search paths, block 65 executes the removal routine. Referring to FIG. 6, block 66 copies the inhibition process 8 file (FORMAT.BAT) from the fixed disk to the distribution disk and restores its original name TRANSFER.EXE. Block 67 erases the FORMAT.BAT and the PLACE.COM or PLACE.EXE files from the fixed disk, and block 68 copies the DOS formatting program file (FORMAT.XXX) from the distribution disk to the fixed disk and restores its original name FORMAT.COM or FORMAT.EXE. When completed, block 69 presents a completion message (FORMAT PROTECTION REMOVED), and block 70 sets the drive back to the original restoration drive, and the program ends. With the format protection now removed, the distribution disk may also be removed, and the DOS formatting capability is completely restored in the computer. 
     The above-described inhibition process, is referred to as being unconditional because the inhibited DOS programs cannot be executed under any conditions. However, the inhibition process may take another form, referred to as conditional inhibition, in which the user may execute inhibited programs under certain conditions. For example, external DOS commands on a designated disk drive of the computer may be used, but not on other drives. Appendix C hereto is a source code listing in PC-DOS commands of the routines for implementing the conditional inhibiting program in a conventional computer having two external drives A: and B:, and a fixed or hard drive C:. Referring to the illustrated embodiment of FIG. 7 the inhibition process will permit a disk on either external drive A: or B: to be formatted, but not the fixed disk of drive C:. The process starts at block 80 when the inhibition program TRANSFER.EXE is on the command path and the command FORMAT entered. Block 81 turns off all messages, and block 82 implements an ASK routine, as disclosed at page 892, PC Magazine DOS Power Tools, supra. This routine presents a message (WISH TO FORMAT EXTERNAL DRIVE (Y/N)? ). If the user enters N for &#34;no&#34;, block 83 clears the screen and block 84 displays the unconditional inhibition message (FORMAT PROTECTION MUST BE REMOVED IN ORDER TO FORMAT HARD DISK MEDIA), and the program ends at block 94. If the user answers Y for &#34;yes&#34;, block 85 clears the screen and block 86 displays a menu (1--FORMAT DRIVE A:, 2--FORMAT DRIVE B:, 3--QUIT). If drive A is selected at block 87, block 88 displays a message (DRIVE A HAS BEEN SELECTED) and block 89 sets the default drive to A: by batch commands; and if drive B is selected at block 90, block 91 displays the selection message (DRIVE B HAS BEEN SELECTED) and block 92 sets the default drive to B:. If the user enters QUIT, the inhibition message of block 84 is displayed and the process ends at block 94. If either drive A: or drive B: is set at default, the disk is formatted by the command XCEL % DRIVE % since the original format command has been renamed, as described below, to XCEL in the distribution disk, and the process ends at block 94. 
     Like the unconditional inhibition, conditional inhibition is not operational until it is installed in the computer. The interception process of FIGS. 3A and 3B is the same as for unconditional inhibition except that the install routine of block 39 (FIG. 3B) is replaced by block 39&#39; of FIG. 8. Block 39&#39; includes a block 95 which copies the substitute inhibition process 8 file (TRANSFER.EXE) and routine ASK.COM, such as disclosed at page 892, PC Magazine DOS Power Tools, supra: and block 96 copies a location marker file PLACE.XXX in the DOS directory and renames it as an executable file PLACE.COM or PLACE.EXE, as appropriate. This informs the computer during the restoration process 9, described below, where to replace the DOS formatting file on the fixed disk. Block 97 erases the inhibition process 8 file from the distribution disk, and block 98 changes the default from external drive A: or B: to drive C:. Block 99 renames the DOS formatting file FORMAT.COM to XCEL.COM and the inhibition file TRANSFER.EXE to FORMAT.BAT; and block 100 renders the renamed formatting file XCEL.COM hidden by means of a HIDE routine, such as disclosed in Samerson et al, supra. page 1017. 
     This completes installation of the conditional inhibition process. Block 47 (FIG. 3B) presents a message to that effect and the process ends. 
     The restoration process for conditional inhibition is essentially the same as for unconditional inhibition except that removal routine 65 is replaced by routine 65&#39;. Referring to FIG. 9, block 65&#39; includes a block 101 which executes a routine UNHIDE, such as disclosed in Samerson et al, supra, page 1131, which brings the hidden renamed file XCEL.COM into view. Block 102 changes the default drive to the fixed disk, and block 103 copies the inhibiting file named FORMAT.BAT to the appropriate drive with the filename TRANSFER.EXE. Block 104 erases the file FORMAT.BAT from the fixed disk, and block 105 renames the formatting file from XCEL.COM to FORMAT.COM. This completes the removal routine. Block 69 presents a completion message, and the process is ended with the message at block 58A. As in the unconditional inhibition process, format protection has been removed and the DOS formatting capability completely restored. 
     Some of the many advantages of the invention should now be readily apparent. For example, a computer program is provided which inhibits the use of executable programs in a disk operating system recorded in a computer. The executable program may be removed from the DOS and placed on a separate removable disk for security purposes. The program is particularly suited for preventing accidental or malicious formatting of disks containing valuable programs or recorded information which would otherwise be destroyed during the formatting process. The program is extremely simple to install and remove without affecting the integrity of other DOS programs and files. 
     It will be understood, of course, that the above-described embodiments are only illustrative of the application of the principles of the present invention. Modifications in these embodiments may be devised by those skilled in the art without departing from the principle and scope of the invention. ##SPC1##