Implement a Write-Ahead Log (WAL) in C

Write a C program that implements a simplified Write-Ahead Log.

Requirements:

• Define a LogRecord struct with: lsn (int), page_id (int), old_value (int), new_value (int), checksum (unsigned int)
• Implement a checksum function: XOR of all fields plus a magic number 0xDEADBEEF
• Implement wal_append() that adds a record to an in-memory log array
• Implement wal_recover() that scans the log and replays changes to a page array
• Simulate a database with 4 pages, initially all zeros
• Simulate transactions:
  • T1: set page 1 to 100, page 2 to 200
  • T2: set page 1 to 150 (overwrite)
  • T3: set page 3 to 300
• Append all changes to the WAL with proper checksums
• Print the WAL contents (each record with LSN, page, old, new, checksum)
• Simulate a crash by resetting pages to a "checkpoint" state: page 1=50, others=0 (simulating that only some changes reached disk)
• Run recovery: replay WAL records where new_value should be applied
• Print pages before and after recovery
• Simulate log corruption by modifying one record's new_value and show that the checksum detects it