RamFS In-Memory File System

RamFS is a lightweight in-memory file system module provided by LibXR. It supports unified management of files, directories, and custom nodes, and is suitable for file access and debugging simulations in embedded systems.

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Main Features

• Organized using a red-black tree structure for files and directories;
• Supports read-only, read-write, and executable file types;
• Supports custom nodes (Custom) for user-defined metadata or extension points;
• Supports recursive search of files, directories, and custom nodes;
• Type-safe data access for all files;
• All data resides entirely in memory, ideal for runtime construction and simulation.

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Core Structures

FsNode

The base class for all nodes, with a unified interface:

• name: node name
• type: node type (FILE / DIR / CUSTOM)
• parent: parent directory

File

Created using CreateFile(), supporting:

• Read-only (READ_ONLY)
• Read-write (READ_WRITE)
• Executable (EXEC): has a Run(argc, argv) method

Dir

Directory class supports adding and finding:

• Add: Add(file), Add(dir), Add(custom)
• Find: FindFile(name), FindDir(name), FindCustom(name), and their recursive variants with Rev

Custom

Custom nodes are used to attach user-defined metadata or extension semantics. Current RamFS is responsible only for naming, attachment, and lookup; it does not impose extra I/O behavior on custom nodes.

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Usage Example

RamFS fs;

int counter = 0;

// Create executable file (increments counter each time it's run)
auto exec_file = RamFS::CreateFile<int*>(
  "runme",
  [](int* arg, int argc, char** argv) {
    UNUSED(argc);
    UNUSED(argv);
    (*arg)++;
    return 0;
  },
  &counter
);

// Create read/write file
auto data_file = RamFS::CreateFile("value", counter);

// Create directory and custom node
auto dir = RamFS::CreateDir("mydir");
auto custom = RamFS::Custom("mycustom");

// Build file system structure
fs.Add(data_file);  // Add to root directory
fs.Add(dir);
dir.Add(exec_file);
dir.Add(custom);

// Run exec file multiple times and verify count
for (int i = 1; i <= 5; ++i) {
  exec_file->Run(0, nullptr);
  ASSERT(data_file->GetData<int>() == i);
}

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Interface Overview

RamFS File System Interface

Method	Description
CreateFile(name, data)	Create a read-only or read-write file
CreateFile(name, exec, arg)	Create an executable file
CreateDir(name)	Create a directory
Add(file/dir/custom)	Add node to root directory
FindFile(name)	Recursively search for a file
FindDir(name)	Search for a directory
FindCustom(name)	Search for a custom node

File Interface

Method	Description
Run(argc, argv)	Run executable file (only for EXEC type)
GetData<T>()	Get a type-safe reference to file data

Dir Interface

Method	Description
Add(node)	Add a file, directory, or custom node
FindFile(name)	Find file in current directory
FindFileRev(name)	Recursively find file
FindDir(name)	Find subdirectory
FindDirRev(name)	Recursively find directory
FindCustom(name)	Find custom node
FindCustomRev(name)	Recursively find custom node

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Application Scenarios

• Simulate file systems in embedded platforms;
• Virtual file access in debug mode;
• Build temporary config, log, or parameter nodes in memory;
• Attach user-defined nodes and debug metadata;

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Unit Test Reference

See [test_ramfs.cpp] for coverage of:

• Executable file execution
• Type-safe data access
• Adding and finding files, directories, and custom nodes