PrismaFS

PrismaFS is a lightweight, layered userspace filesystem inspired by Plan 9. It allows you to overlay a base filesystem with session-specific layers, providing isolated views and changes without affecting the original data.

Features

• Layered filesystem design inspired by Plan 9's namespace philosophy.
• Per-session modifications that do not alter the base layer.
• Transparent file and directory operations.
• Implemented as a user-space filesystem using macFUSE.

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Requirements

To use PrismaFS, you need:

• macFUSE: Install it from https://osxfuse.github.io/.
• A POSIX-compliant environment (macOS or a UNIX-like system).
• Clang or cc (preferred). GCC is supported but not recommended.

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Installation

Building PrismaFS

To build PrismaFS from the source, use the provided Makefile:

make

If you prefer to use GCC, you can override the default compiler by running:

make CC=gcc

Installing PrismaFS

To install PrismaFS to /usr/local/bin (or another directory in your PATH):

sudo make install

You can now run prismafs.

Uninstalling PrismaFS

To remove the installed binary:

sudo make uninstall

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Compile and Development

• Preferred (Clang):

clang -Wall -o prismafs prismafs.c -D_FILE_OFFSET_BITS=64 -I/usr/local/include /usr/local/lib/libosxfuse.2.dylib

• GCC:

gcc -Wall -o prismafs prismafs.c -D_FILE_OFFSET_BITS=64 -I/usr/local/include /usr/local/lib/libosxfuse.2.dylib

Notes:

When using macFUSE, its libraries are placed in /usr/local/lib:

find /usr/local/lib -name "libosxfuse*" /usr/local/lib/libosxfuse.2.dylib /usr/local/lib/libosxfuse_i64.2.dylib

Headers are located in:

sudo ls /usr/local/include fuse fuse.h node

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Usage

Running PrismaFS

1. Set up the required environment variables:

   • BASE_LAYER_DIR: The directory to be used as the base layer (e.g., /).
   • SESSION_LAYER_DIR: The directory to store session-specific changes (e.g., /tmp/prismafs_session).

   Example:

export BASE_LAYER_DIR=/ export SESSION_LAYER_DIR=/tmp/prismafs_session

2. Mount PrismaFS to a directory:

mkdir /tmp/prismafs_mount ./prismafs /tmp/prismafs_mount

3. Use the mounted directory (/tmp/prismafs_mount) to view and modify files:
   • Changes in this directory are isolated to the session layer.
   • Base layer files remain unmodified.

Cleaning Up

To unmount PrismaFS:

umount /tmp/prismafs_mount

Or:

fusermount -u /tmp/prismafs_mount

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License

PrismaFS is licensed under the Apache License 2.0. See the LICENSE file for details. Website: ithas-site.com