Operating Systems (CS330)

Repository Overview

This repository houses my solutions to the assignments completed during the Operating Systems Course (CS330) in the 5th semester at IIT Kanpur under the guidance of Prof. Debadatta Mishra. The solutions presented here reflect the hands-on experience gained in implementing various critical aspects of operating systems, including memory management, system calls, and fault handling.

Assignments Overview

Assignment 1: Dynamic Memory Management and Directory/File Size Calculation

• Objective: Implement API functions for dynamic memory allocation and deallocation, along with a utility to recursively calculate the size of any directory or file, including symbolic links.
• Implementation Highlights:
  • Developed a robust memalloc() and memfree() library, optimized to reduce memory fragmentation.
  • Implemented recursive directory size calculation, accounting for symbolic links.

Assignment 2: Trace Buffer and Tracing Utilities Implementation in GemOS

• Objective: Extend GemOS to include trace buffer functionality (similar to pipe() functionality in UNIX), and implement strace() and ftrace() utilities
• Implementation Highlights:
  • Implemented the trace buffer functionality, supporting create_pipe(), read(), write(), and close_pipe() functionalities.
  • Developed strace() and ftrace() utilities to intercept and record system calls and function calls invoked by a process.
  • Integrated a fault handler to manage trace buffer overflows.
  • Validated write and read syscalls based on the read/write access permissions of code, data, heap, and stack segments.

Assignment 3: Kernel-Level Memory Management with mmap, munmap, mprotect, and Copy-on-Write Fork

• Objective: Implement the mmap(), munmap(), and mprotect() system calls. Develop the cfork() syscall using a Copy-on-Write (CoW) fault handler to support lazy memory allocation.
• Implementation Highlights:
  • Extended the GemOS codebase to include the mmap(), munmap(), and mprotect() system calls.
  • Implemented a cfork() system call triggered by page faults supporting lazy allocation.

Additional Notes

• Object Files: For Assignments 2 and 3, object files for various components were provided. The task was to modify and implement specific files: tracer.c for Assignment 2 and v2p.c for Assignment 3.