Simple Filesystem in C

This project is a simple block-based, inode-style filesystem written in C for my Operating Systems course (Spring 2025). It runs on top of a simulated software disk provided via softwaredisk.c.

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👨‍💻 Authors

• Carter Mauer
• Cole Heausler

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🗂️ Project Structure

simple-filesystem-c/
├── src/
│   ├── filesystem.c
│   ├── formatfs.c
│   ├── softwaredisk.c
│   ├── filesystem.h
│   ├── softwaredisk.h
├── tests/
│   ├── testfs0.c
│   ├── testfs4a.c
│   └── exercisesoftwaredisk.c
├── README.md
├── filesystem_design.pdf
├── assignment-instructions.pdf
└── .gitignore

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💾 Disk Layout

Block Range	Purpose
0	Data Block Bitmap
1	Inode Bitmap
2–5	Inodes (4 blocks, 128 per block = 512 total)
6–69	Directory Entries (64 blocks, 8 entries/block)
70–4095	File Data Blocks

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📦 Filesystem Features

• Inode-based structure with 13 direct and 1 indirect pointer
• Flat directory layout (single-level, no subdirectories)
• 512 max files
• ~8 MB max file size per file
• Supports filenames up to 507 characters
• Bitmaps used for inode and block allocation
• Persistent storage through softwaredisk backend
• Error handling through fserror enum and fs_print_error()

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⚙️ Building & Running

Navigate to the src/ folder and build everything using make:

cd src/
make

Format the Disk

./formatfs

Run Tests

./testfs0     # Simple test
./testfs4a    # Alignment test

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🔒 Error Handling

All file operations set the global variable fserror. You can check the result of any operation using:

fs_print_error();

Common error types include:

• FS_OUT_OF_SPACE
• FS_FILE_ALREADY_EXISTS
• FS_FILE_NOT_FOUND
• FS_IO_ERROR

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🛑 Limitations

• No support for subdirectories
• No permissions or timestamps
• Not thread-safe (single-process only)
• No crash recovery

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📄 Design Document

See filesystem_design.md for a detailed breakdown of the physical layout, file structures, and implementation limits.

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🧪 License

This project was developed as an educational assignment for CSC 4103. Not intended for production or commercial use.