PROGRAM, METHOD, AND SYSTEM FOR CODE CONVERSION

• US 20110321018A1
• Filed: 06/15/2011
• Published: 12/29/2011
• Est. Priority Date: 06/29/2010
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Tatsubori, Michiaki
• Application Number:
  US13/160,796
• Publication Number:
  US 20110321018A1
• Time in Patent Office: Days
• US Class Current: 717/137
• CPC Class Codes: G06F 8/53 Decompilation; Disassembly
• CPC Class Codes: G06F 8/74 Reverse engineering; Extracting design information from source code

Abstract

A program product, a method and a system for enhancing the readability of Java® source code obtained by decompiling Java® bytecode. Code which does not directly correspond to language of a second programming language and which is intended to execute an instruction related to a stack operation, is replaced with any combination of an expression for assignment to a temporary variable, a call for a dummy method which only returns part of an argument as-is, and an expression for reading the temporary variable. Code for calling a method which does not correspond to a second programming language and which leaves its value on the stack and has no return value is replaced by a new method. The new method, having an additional first argument and the original argument, executes the original method call and returns the additional first argument as-is.

Claims

1. An article of manufacture tangibly embodying computer readable instructions which, when implemented, cause a computer to carry out the steps of a method of converting a code so that an executable bytecode generated by a processor for a first programming language corresponds to source code written in a second programming language, the steps of the method comprising:

sequentially reading instructions in the executable bytecode generated by the processor for the first programming language;

when a first code is found which does not directly correspond to any language element of the second programming language and which is intended to execute an instruction related to a stack operation, replacing the first found code with any combination of an expression for assignment to a temporary variable, a call for a dummy method which only returns part of an argument as-is, and an expression for reading the temporary variable; and

when a second code is found which does not directly correspond to any language element of the second programming language and which is intended to call an original method which leaves a value thereof on a stack and has no return value, generating a new method which has an additional first argument and an original argument, wherein the new method executes the original method call, and returns the additional first argument as-is, and replacing the call for the original method having no return value with a call for the new method.

2. The article of manufacture according to claim 1, further comprising the step of preprocessing so as not to introduce excess temporary variables.

3. The article of manufacture according to claim 1, further comprising the step of postprocessing so as to generate bytecode which can be easily decompiled by a decompiler which does not introduce temporary variables.

4. The code conversion program product according to claim 1, wherein

the first programming language is a PHP language, and

the second programming language is Java.

5. A code conversion method of converting code using a computer so that executable bytecode generated by a processor for a first programming language corresponds to source code written in a second programming language, the method comprising the steps of:

sequentially reading instructions in the executable bytecode generated by the processor for the first programming language by using the computer;

when a first code is found which does not directly correspond to any language element of the second programming language and which is intended to execute an instruction related to a stack operation, replacing the first found code with any combination of an expression for assignment to a temporary variable, a call for a dummy method which only returns part of an argument as-is, and an expression for reading the temporary variable by using the computer; and

when a second code is found which does not directly correspond to any language element of the second programming language and which is intended to call an original method which leaves a value thereof on a stack and has no return value, generating a new method which has an additional first argument and an original argument, wherein the new method executes the original method call, and returns the additional first argument as-is and replacing the call for the original method having no return value with a call for the new method by using the computer.

6. The code conversion method according to claim 5, wherein

the first programming language is a PHP language, and

the second programming language is Java.

7. A computer implemented code conversion system for converting code so that executable bytecode generated by a processor for a first programming language corresponds to source code written in a second programming language, the system comprising:

means that sequentially reads instructions in the executable bytecode generated by the processor for the first programming language;

means that, when finding a first code which does not directly correspond to any language element of the second programming language and which is intended to execute an instruction related to a stack operation, replaces the first found code with any combination of an expression for assignment to a temporary variable, a call for a dummy method which only returns part of an argument as-is, and an expression for reading the temporary variable; and

means that, when finding a second code which does not directly correspond to any language element of the second programming language and which is intended to call an original method which leaves a value thereof on a stack and has no return value, generates a new method, the new method having an additional first argument and an original argument, executing the original method call, and returning the additional first argument as-is, and replaces the call for the original method having no return value with a call for the new method.

8. The code conversion system according to claim 7, wherein

the first programming language is a PHP language, and

the second programming language is Java.