#!/usr/bin/env node
/**
* Patch script for web-llm FFI compatibility
*
* This script adds missing TVM FFI stub functions to the web-llm bundle
* to enable compatibility with custom-compiled WASMs that have additional
* FFI imports (like TVMFFIEnvSetStream for stream management).
*
* Usage: node scripts/patch-webllm-ffi.js
*/
const fs = require('fs');
const path = require('path');
const WEB_LLM_INDEX = path.join(__dirname, '../node_modules/@mlc-ai/web-llm/lib/index.js');
// Stub function definitions to add (no-ops for WebGPU since streams aren't used)
const STUB_FUNCTIONS = `
// === BEGIN CUSTOM FFI STUBS ===
// Added by patch-webllm-ffi.js for extended context window WASM compatibility
function _TVMFFIEnvSetStream(){return 0;}_TVMFFIEnvSetStream.stub=true;
function _TVMFFIEnvGetStream(){return 0;}_TVMFFIEnvGetStream.stub=true;
// === END CUSTOM FFI STUBS ===
`;
// Pattern to find existing stub functions (they're defined right before wasmImports)
const STUB_MARKER = 'function _TVMFFIWasmFunctionDeleter()';
// Pattern to find the specific TVM wasmImports (the one with TVMFFIWasmFunctionDeleter)
const TVM_WASM_IMPORTS_PATTERN = /wasmImports=\{TVMFFIWasmFunctionDeleter[^}]+\}/;
function patchWebLLM() {
console.log('Patching web-llm FFI imports...');
if (!fs.existsSync(WEB_LLM_INDEX)) {
console.error('Error: web-llm index.js not found at:', WEB_LLM_INDEX);
process.exit(1);
}
let content = fs.readFileSync(WEB_LLM_INDEX, 'utf8');
// Check if already patched (look for our specific function definition)
if (content.includes('function _TVMFFIEnvSetStream()')) {
console.log('Already patched! Skipping.');
return;
}
// Find the stub function marker and insert our stubs before it
const stubIndex = content.indexOf(STUB_MARKER);
if (stubIndex === -1) {
console.error('Error: Could not find stub function marker');
process.exit(1);
}
// Insert our stub functions
content = content.slice(0, stubIndex) + STUB_FUNCTIONS + content.slice(stubIndex);
// Now extend wasmImports to include our new stubs
const match = content.match(TVM_WASM_IMPORTS_PATTERN);
if (!match) {
console.error('Error: Could not find TVM wasmImports object (looking for one with TVMFFIWasmFunctionDeleter)');
process.exit(1);
}
// Insert our new entries just before the closing brace
const originalImports = match[0];
const newImports = originalImports.replace(/\}$/, ',TVMFFIEnvSetStream:_TVMFFIEnvSetStream,TVMFFIEnvGetStream:_TVMFFIEnvGetStream}');
content = content.replace(originalImports, newImports);
// Write back
fs.writeFileSync(WEB_LLM_INDEX, content);
console.log('Patch applied successfully!');
console.log('Added stubs for: TVMFFIEnvSetStream, TVMFFIEnvGetStream');
}
// Also patch the source map if it exists
function patchSourceMap() {
const mapFile = WEB_LLM_INDEX + '.map';
if (fs.existsSync(mapFile)) {
// Just note that source map is now stale
console.log('Note: Source map at', mapFile, 'is now stale');
}
}
patchWebLLM();
patchSourceMap();
