lyng/docs/lyngio.md

lyngio — Extended I/O and System Library for Lyng

lyngio is a separate library that extends the Lyng core (lynglib) with powerful, multiplatform, and secure I/O capabilities.

Why a separate module?

1. Security: I/O and process execution are sensitive operations. By keeping them in a separate module, we ensure that the Lyng core remains 100% safe by default. You only enable what you explicitly need.
2. Footprint: Not every script needs filesystem or process access. Keeping these as a separate module helps minimize the dependency footprint for small embedded projects.
3. Control: lyngio provides fine-grained security policies (FsAccessPolicy, ProcessAccessPolicy) that allow you to control exactly what a script can do.

Included Modules

• lyng.io.fs: Async filesystem access. Provides the Path class for file/directory operations, streaming, and globbing.
• lyng.io.process: External process execution and shell commands. Provides Process, RunningProcess, and Platform information.

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Quick Start: Embedding lyngio

1. Add Dependencies (Gradle)

repositories {
    maven("https://gitea.sergeych.net/api/packages/SergeychWorks/maven")
}

dependencies {
    // Both are required for full I/O support
    implementation("net.sergeych:lynglib:0.0.1-SNAPSHOT")
    implementation("net.sergeych:lyngio:0.0.1-SNAPSHOT")
}

2. Initialize in Kotlin (JVM or Native)

To use lyngio modules in your scripts, you must install them into your Lyng scope and provide a security policy.

import net.sergeych.lyng.Script
import net.sergeych.lyng.io.fs.createFs
import net.sergeych.lyng.io.process.createProcessModule
import net.sergeych.lyngio.fs.security.PermitAllAccessPolicy
import net.sergeych.lyngio.process.security.PermitAllProcessAccessPolicy

suspend fun runMyScript() {
    val scope = Script.newScope()
    
    // Install modules with policies
    createFs(PermitAllAccessPolicy, scope)
    createProcessModule(PermitAllProcessAccessPolicy, scope)
    
    // Now scripts can import them
    scope.eval("""
        import lyng.io.fs
        import lyng.io.process
        
        println("Working dir: " + Path(".").readUtf8())
        println("OS: " + Platform.details().name)
    """)
}

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Security Tools

lyngio is built with a "Secure by Default" philosophy. Every I/O or process operation is checked against a policy.

• Filesystem Security: Implement FsAccessPolicy to restrict access to specific paths or operations (e.g., read-only access to a sandbox directory).
• Process Security: Implement ProcessAccessPolicy to restrict which executables can be run or to disable shell execution entirely.

For more details, see the specific module documentation:

• Filesystem Security Details
• Process Security Details

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Platform Support Overview

Platform	lyng.io.fs	lyng.io.process
JVM	✅	✅
Native (Linux/macOS)	✅	✅
Native (Windows)	✅	🚧 (Planned)
Android	✅	❌
NodeJS	✅	❌
Browser / Wasm	✅ (In-memory)	❌