Exitor

Exitor is a special text editor (Basic vi editor ) built on XV6 operating system.

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Exitor - A Minimal Text Editor for xv6

Exitor is a minimalist VI-like text editor built for the xv6 operating system. It provides basic file editing capabilities, copy-paste functionality, and a custom dynamic memory management system via user-defined system calls.

Features

  • Modes

    • Insert Mode – Press i to start typing.
    • Command Mode – Press ESC to enter command input.

  • Commands

    • :w → Save the file
    • :q → Quit without saving
    • :wq → Save and quit
    • :y → Yank (copy) lines
      • After typing :y, press Enter, then input the start line, press Enter, and input the end line.
    • :p → Paste the previously yanked lines

  • Clipboard Support

    • Yanked lines are stored in a fixed-size clipboard buffer (1024 bytes).
    • Only line-based copy-paste is supported.

  • Dynamic Memory Allocation (Custom)

    • xmalloc(), xfree(), xcalloc(), and xrealloc() system calls implemented.
    • Uses a simple header-based allocator with validation and free-list management.

System Calls Added

System Call Description
xmalloc(n) Allocate n bytes of memory
xfree(ptr) Free previously allocated memory at ptr
xcalloc(n, s) Allocate and zero-initialize n * s bytes
xrealloc(ptr, size) Reallocate memory at ptr to size
clear() Clears the screen (terminal)
hello() Prints "Hello World" to the console
exitor() Prints Exitor banner and usage instructions

Building & Running

  1. Clone or integrate this project into your xv6 source tree.
  2. Rebuild xv6 using:
   make clean 
   make qemu-nox (Use qemu-nox for better UI)

Usage

To run Exitor inside xv6:

exitor <filename>

Example:

exitor notes.txt

Hint

If you are cloning this repo for your xv6 project, consider making the copy and paste functions system calls for better modularity and privilege separation. Since I added them as normal functions.

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