MiniDB

A project for NYCU Unix Programming 2024.

About the Debugger

MiniDB is an interactive debugger designed for debugging 64-bit x86-64 assembly-level instructions. It supports debugging of static non-Position Independent Executable (non-PIE) programs on x86-64 architecture.

You can run the following command to inspect its properties:

$ file <program_name>

Usage

Load the target program before starting to debug:

$ ./mdb <program_name>

$ ./mdb
(mdb) load <program_name>

Supported Commands

• Step Instruction
• Continue Execution
• Show Registers Info
• Breakpoint: Set, Show Info, and Delete
• Patch Memory
• System Call

Step Instruction

Execute a single assembly instruction.

(mdb) si

Continue Execution

Continue the execution of the target program until it terminates or hits a breakpoint.

(mdb) cont

Show Registers Info

Show all the registers and their corresponding values in hexadecimal format.

(mdb) info reg

Breakpoint: Set, Show Info, and Delete

Set breakpoint

Sets a breakpoint at a specific memory address in hexadecimal format.

(mdb) break <hex address>

Show Breakpoints Info

Lists all active breakpoints, showing their ID and address.

(mdb) info break

Delete Breakpoint

Removes a breakpoint by its ID.

(mdb) delete <id>

Patch Memory

Modifies the memory starting at a specified address. The value will be written in hexadecimal, and the length in bytes can be 1, 2, 4, or 8.

(mdb) patch <hex address> <hex value> <len>

System Call

The program execution should break at every system call instruction unless it hits a breakpoint.

(mdb) syscall