JPH01214934A - System for detecting indirect recursive calling of program - Google Patents

Abstract

PURPOSE:To prevent an executable program which uses a program as a constituent routine from getting into an infinite loop by making detection of indirect recursive calling of the program executable at the time of execution of the program. CONSTITUTION:Whether or not the content of an address saving area 9 is vacant value is discriminated by means of a vacant value discriminating means 2 and, when the content is a vacant value, a returning address '1' is stored in the area 9 by means of a returning address storing means 3. Then the content of the area 9 is copied and stored in a temporary address saving area 10 by means of an address area copying means 6. Thereafter, the returning address '1' is fetched by means of a returning address branching means 8 and branched to the returning address 1 in a calling-side program. When the content is not a vacant value, it is discriminated that indirect recursive calling is executed to a program 100 and abnormal termination of the program 100 is executed by an interrupting instruction executing means 4. Therefore, an executable program which uses a program as a constituent routine can be prevented from getting into an infinite loop.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for detecting indirect recursive calls of programs;
In particular, the present invention relates to a method for detecting indirect recursive calls to programs in data processing systems in which recursive calls to programs are prohibited.

[Conventional technology]

Conventionally, program recursive call detection methods detect program recursive calls in data processing systems where program recursive calls are prohibited. The only thing that needed to be done was to detect errors (calls to programs) and perform error diagnosis (notify the program creator that there is an error in the structure of the program and prompt them to modify the program).

Regarding indirect recursive calls of programs (calls of a specific program within another program called by a specific program), since the state of other programs is not known at the time of compiling a program, the recursion of the program described above is Call detection methods were unable to detect this (even when the translated program was executed as one of the constituent routines of an executable program, it was not possible to detect and deal with indirect recursive calls to the program).

[Problem to be solved by the invention]

In the conventional program recursive call detection method described above,
Error diagnosis is only performed by detecting direct recursive calls to a program when compiling a program, but indirect recursive calls to a program cannot be detected at the time of translation or execution. If you create a program that performs this, there is a drawback that an infinite loop will occur when an executable program that uses the program as a constituent routine is executed.

In view of the above-mentioned points, an object of the present invention is to detect indirect recursive calls when executing a program that makes indirect recursive calls,
To provide a recursive call detection method for a program (indirect recursive call detection method for a program) that prevents falling into an infinite loop when executing an executable program whose constituent routine is a program that makes an indirect recursive call.

[Means to solve the problem]

The indirect program indirect recursive call detection method of the present invention, in a data processing system in which recursive program calls are prohibited and has a program interrupt instruction, initializes the return address save area in the program with an upper value when the program is loaded into memory. an upper price initializing means for initializing the upper value; an upper value identifying means within the program for identifying whether the contents of the return address save area are an upper value at a program entry point; Interrupt instruction execution means in the program that executes a program interrupt instruction to abnormally terminate the program when the contents of the save area are not at the upper value, and identification by the upper value identification means that the contents of the return address save area are at the upper value. return address storage means within the program for storing a return address to the calling program passed from the calling program in the return address save area in a certain case; and the return address save area after execution of a predetermined process in the program. address area copying means in the program for copying the contents of the return address to the temporary address saving area in the program; Upper value setting means in the program that sets an upper value in the return address save area; and return address branching means in the program that branches to a return address in the calling program stored in the temporary address save M area. and has.

[Effect]

In the program indirect recursive call detection method of the present invention, the upper value initializing means initializes the return address save area in the program with the upper value when the program is loaded into the memory, and the upper value identifying means in the program detects the return address at the program entry point. The interrupt instruction execution means in the program identifies whether the contents of the save area are the upper value or not, and executes the program interrupt instruction when the contents of the return address save area are not the upper value as identified by the upper value identifying means. When the return address storage means in the program terminates abnormally and the contents of the return address save area are the upper value as identified by the upper value identification means, the return address passed from the calling program to the calling program is stored in the return address save area. The address area copying means in the program copies the contents of the return address save area to the temporary address save area in the program after executing a predetermined process in the program, and the upper value setting means in the program copies the contents by the address area copying means. After the contents of the return address save area are stored in the temporary address save area during processing, the upper value is set in the return address save area, and the return address branching means in the program executes a return in the calling program that is stored in the temporary address save area. Branch to address.

〔Example〕

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

FIG. 1 is a block diagram showing the structure of an embodiment of the method for detecting indirect recursive calls of programs according to the present invention. The program indirect recursive call detection method of this embodiment includes a return address 1, an upper value identification means 2, a return address storage means 3, an interrupt instruction execution means 4, a program processing means 5,
Address area copying means 6, upper value setting means 7, return address branching means 8, return address saving area 9, temporary address saving area 10, program entry point 11, program end point 12, upper value initializing means 13.

Components indicated by numerals 2 to 12 in FIG. 1 are included in a program 100 that is one of the configuration routines of an executable program (not shown) generated through translation processing and linked editing processing. (generated when the program 100 is translated).

Next, the operation of the indirect recursive call detection method of the program of this embodiment configured as described above will be explained.

When the program 100 is loaded into a memory (not shown) in a data processing system to which the program indirect recursive call detection method of this embodiment is applied, the return address save area 9 is set to an upper value (a value that does not indicate any address or address). For example, O3 (Opera
ting System (not shown) or the like.

Program 100 loaded into memory in this way
A call from a calling program (not shown; other programs constituting the executable program or O3) returns at return address 1 (address in the calling program that returns when the specified processing of the program 100 is completed).
This is done by calling the program entry point 11 with the .

At the program entry point 11, the upper price identification means 2 is activated.

The upper price identification means 2 identifies whether the contents of the return address save area 9 are the upper price.

If the content of the return address save area 9 is an upper value in this identification, the return address storage means 3 is activated.

In the return address storage means 3, the return address 1 passed when the program entry pointer 1 is called is stored in the return address save area 9.

Next, control is passed to the program processing means 5, a predetermined process is executed, and after the execution, the address area copying means 6 is activated.

In the address area copying means 6, the return address saving area 9
The contents are copied and stored in the temporary address save area 1o.

Next, the upper value setting means 7 is activated, and the upper value is set in the return address save area 9.

Further, the return address branching means 8 is activated, the return address 1 stored in the temporary address save area 10 is taken out, and a branch (return) to the return address l in the calling program is performed.

When the contents of the return address save area 9 are not an upper price in identifying whether the contents of the return address save area 9 are an upper price in the upper price identifying means 2 (the program processing means 5
After the predetermined processing in , before the upper price setting means 7 sets the upper price, the program 100 is called again from the other program via the program processing means 5 (indirect recursive call). Because of this, the contents of the return address save area 9 are not at the upper value. Note that error diagnosis is performed for direct recursive calls when the program 100 is translated, so the only recursive calls that occur are indirect recursive calls). , the interrupt instruction execution means 4 is activated.

In the interrupt instruction execution means 4, control is transferred to the program end point 12, and the program 100 ends abnormally (this abnormal end causes the program 100 and the calling program (O
Execution of the entire executable program whose constituent routines are 3) is completed. This prevents the executable program whose constituent routine is program 100 from falling into an infinite loop.

〔Effect of the invention〕

As explained above, the present invention enables detection of indirect recursive calls of programs during program execution in data processing systems where recursive calls of programs are prohibited, thereby executing programs that make indirect recursive calls of programs. This has the effect of preventing an executable program that has this program as a constituent routine from falling into an infinite loop.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, 1...Return address, 2...Upper value identification means, 3...Return address storage means, 4...Interrupt instruction execution means, 5...Program processing means, 6...Address area Copying means, 7... Upper value setting means, 8... Return address branching means, 9... Return address saving area, 10... Temporary address saving area, 11... Program entry point, 12... Program end point, 13...Upper price initialization means, 100...Program.

Claims (1)

[Claims] In a data processing system in which recursive calling of a program is prohibited and has a program interrupt instruction, a null value initialization method is provided for initializing a return address save area in the program with a null value when the program is loaded into memory. null value identification means in the program for identifying whether or not the contents of the return address save area are null values at a program entry point; Interrupt instruction execution means within the program that executes a program interrupt instruction to abnormally terminate the program if the content is not a null value; and an interrupt instruction execution means in the program that abnormally terminates the program when the content is not a null value; return address storage means within the program for storing a return address to the calling program passed from the calling program in the return address save area in a certain case; and the return address save area after execution of a predetermined process in the program. address area copying means in the program for copying the contents of the return address saving area to a temporary address saving area in the program; A null value setting means in the program that sets a null value in the return address save area; and a return address branch in the program that branches to a return address in the calling program stored in the temporary address save area. An indirect recursive call detection method for a program, comprising: means.