File Explorer

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Key Tools

In order to ensure that my code was working, I utilized 2 debugging tools:

• GDB: This allowed me to go instruction by instruction and inspect the state of the program, which was especially useful when tracking “segfaults”
• Valgrind: This allowed me to see how memory was being utilized by our program, and ensure that we were allocating and freeing memory correctly.

Homework 1: C Data Structures Implementation

Overview

Implemented two fundamental C data structures from scratch:

• Doubly-linked list with iterator support
• Chained hash table with dynamic resizing

Key Features

• Generic payload support for storing arbitrary data types
• Memory management with proper malloc/free handling
• Iterator abstractions for safe data structure traversal
• Robust error handling using Verify333 assertions

Technical Implementation

• LinkedList: Managed head/tail pointers with node splicing logic
• HashTable: Used FNV hashing with separate chaining collision resolution
• Memory safety: Comprehensive Valgrind testing for leaks and errors
• Code quality: Followed Google C++ style guide with cpplint validation

Homework 2: In-Memory Search Engine

Overview

Built a file system crawler, indexer, and query processor using HW1 data structures.

Components Implemented

Part A: File Parser

• Text file ingestion with memory-efficient string handling
• Word parsing using alphabetic character separation
• Position tracking with byte offset recording
• Case normalization converting all words to lowercase

Part B: Crawler and Indexer

• Recursive directory traversal with document ID assignment
• Inverted index construction mapping words → documents → positions
• Document table management for filename ↔ docID bidirectional lookup

Part C: Query Processor

• Multi-word query processing with result intersection
• Ranking algorithm based on term frequency summation
• Interactive shell with console-based user interface

Data Structures Used

• Document table: Dual hash tables for bidirectional lookup
• Inverted index: Nested hash tables (word → docID → positions)
• Position tracking: Linked lists maintaining sorted offsets

Homework 3: Disk-Based Search Engine

Overview

Extended HW2 search engine to persistent storage with architecture-neutral file format.

Components Implemented

Part A: Index Marshaller

• Big-endian serialization for cross-platform compatibility
• Complex file format with header, doctable, and index regions
• Checksum validation for data integrity verification
• Hierarchical data storage maintaining in-memory structure relationships

Part B: Index Reader

• C++ class hierarchy for file-based data structure access
• Efficient lookup algorithms for query processing
• Memory-mapped style access without full file loading

Part C: Multi-Index Search Shell

• Multiple index file support for distributed searching
• Rank aggregation across multiple corpora
• Interactive query interface with result merging

File Format Features

• Magic number identification (0xCAFEF00D)
• Embedded hash tables with bucket chaining
• Variable-length string storage
• Position list compression and sorting

Final Project: Web Server Security & Session Management

Security Features Implemented

Session Management

• Secure cookie generation with session tracking
• HMAC-SHA256 protection against cookie tampering
• Session validation with cryptographic verification

Authentication System

• Login page with credential processing
• Admin cookie minting for privileged access
• Plaintext authentication (noted as potential security concern)

Access Control

• Admin-only routes (/quitquitquit endpoint protection)
• Protected file access for $(BASE_DIR)/admin contents
• Role-based authorization using session cookies

Administrative Features

• Server logging of client requests and activities
• Admin dashboard with system overview
• Navigation system with role-appropriate links

Technical Implementation Details

• Cookie security: HMAC verification prevents unauthorized modifications
• Access enforcement: Session validation on protected endpoints
• User experience: Seamless navigation between public and admin areas
• Monitoring: Comprehensive request logging for administrative oversight