Method for reconstructing debugging information for a decompiled executable file

• US 6,151,701 A
• Filed: 09/28/1998
• Issued: 11/21/2000
• Est. Priority Date: 09/30/1997
• Status: Expired due to Fees

• Current Assignee: Ahpah Software, Inc.
• Original Assignee: Ahpah Software, Inc.
• Inventors: Martino, Paul J., Humphreys, Greg
• Primary Examiner(s): Hafiz, Tariq R.
• Assistant Examiner(s): ZHEN, WEI Y
• Application Number:
  US09/162,472
• Time in Patent Office: 785 Days
• Field of Search: 717/4
• US Class Current: 717/130
• CPC Class Codes: G06F 11/362 Software debugging
• CPC Class Codes: G06F 8/53 Decompilation; Disassembly

Abstract

A debugging system according to the present invention includes a decompiler that provides information to a table generator, which generates a line number map and a symbol table, each of which corresponds to an executable file being decompiled. In a specific embodiment, hooks into specific operations performed by the decompiler trigger the table generator operation. A debugging information program can be hooked into a decompiler to generate the debugging information and modify the source code output by the decompiler. For example, the program can be hooked into the decompiler to monitor when the decompiler inserts or deletes source statements, generates line numbers for source lines, or assigns variable names to variables encountered in the executable code.

Claims

1. A decompiler for decompiling target executable code into target source code with debugging information, wherein executable code comprises a plurality of instructions for a particular computing environment and source code comprises a plurality of instructions in a form readable by programmers, and wherein the target executable code is a result of compiling initial source code, the decompiler comprising:

source generation means for generating one or more source statements of the target source code from one or more instructions of the target executable code, wherein the one or more source statements are such that a compiler for the particular computing environment would compile the one or more source statements into the one or more instructions of the target executable code, or functionally equivalent instructions which are functionally equivalent to the one or more instructions of the target executable code, wherein the source generation means includes hooks for incorporating additional functionality at a plurality of hook points in the source generation means; and

means for generating debugging information independent of the initial source code, the debugging information being information about source code that would correspond to the target executable code, wherein the means for generating debugging information comprises additional functionality hooked at the plurality of hook points to generate the debugging information in response to the decompiler processing through each of the plurality of hook pints.

2. The decompiler of claim 1, wherein the debugging information includes a line number map, which maps line numbers between the target executable code and the target source code, and a symbol table, which maps source data element names to executable data elements.

3. The decompiler of claim 1, wherein the plurality of hook points include at least:

a first hook that is executed when the source generation means generates one or more source statements of the target source code from one or more instructions of the target executable code;

a second hook that is executed when the source generation means deletes a source statement of the target source code; and

a third hook that is executed when the source generation means inserts a source statement of the target source code.

4. The decompiler of claim 3, wherein the plurality of hook points further comprise:

a fourth hook that is executed when the source generation means generates a nonstatement line of source text in the target source code; and

a fifth hook that is executed when the source generation means assigns a source data element name to data element encountered in the target executable code.

5. The decompiler of claim 4, wherein the additional functionality added at the fourth hook includes logic to add line numbering for nonstatement lines where indicated by a readability format.

6. The decompiler of claim 1, further comprising means for organizing the target source code and the debugging information into a class file in a format expected by a class file debugger.

7. The decompiler of claim 1, wherein the target executable code comprises one or more executable code files and the target source code comprises one or more source code files.

8. The decompiler of claim 1, wherein the target executable code comprises instructions that are native instructions for a particular computing environment.

9. The decompiler of claim 1, wherein the target executable code comprises a plurality of instructions which are in an intermediate form readily convertible into native instructions for a particular computing environment.

10. The decompiler of claim 1, wherein the target source code includes comments.