LC

Parse a .class File Format Manually

hard2/8

Inspect Java Bytecode with javap -c Implement a Minimal JVM That Runs Hello World

Language

Compiler

2.0s Limit 256MB

Implementation

Write a C program that parses a simulated .class file header and constant pool.

Requirements:

Define a binary buffer representing a minimal .class file with magic CAFEBABE
Extract and print the magic number in hexadecimal
Extract and print minor and major version numbers
Extract and print the constant pool count
Parse at least one UTF-8 constant pool entry and print the class name
Output must contain the strings: .class, CAFEBABE, constant pool, and parse

Why This Matters

0xCAFEBABE and this exact constant-pool layout are specified byte-for-byte in JVMS chapter 4, and bytecode-manipulation libraries like ASM and Javassist — which power Spring's AOP proxies and Java APM agents — parse this identical structure at class-load time. Understanding the raw format is what lets you read a corrupted class file error or write a custom bytecode transformer instead of treating .class files as an opaque blob.

Hints

0 / 3 revealed

Validation Suite

main.c

Workspace 1.0