File System Operations

/**
 * Downloads files to the local filesystem with support for incremental builds
 * @param files - Map of file paths to File objects
 * @param basePath - Base directory to download files to
 * @param meta - Optional metadata for build context
 * @returns Promise resolving to downloaded files as FileFsRef objects
 */
function download(files: Files, basePath: string, meta?: Meta): Promise<DownloadedFiles>;

interface DownloadedFiles {
  [filePath: string]: FileFsRef;
}

import { download, FileFsRef } from "@now/build-utils";

// Download files for build
const files = {
  "index.js": new FileFsRef({ fsPath: "/src/index.js" }),
  "package.json": new FileFsRef({ fsPath: "/src/package.json" })
};

const downloadedFiles = await download(files, "/tmp/build");
// Files are now available in /tmp/build/

/**
 * Find files matching glob patterns
 * @param pattern - Glob pattern to match files against
 * @param options - Optional glob configuration
 * @returns Promise resolving to array of matching file paths
 */
function glob(pattern: string, options?: GlobOptions): Promise<string[]>;

interface GlobOptions {
  cwd?: string;
  ignore?: string | string[];
  dot?: boolean;
  matchBase?: boolean;
  nodir?: boolean;
}

import { glob } from "@now/build-utils";

// Find all JavaScript files
const jsFiles = await glob("**/*.js", { cwd: "/project" });

// Find TypeScript files, ignoring node_modules
const tsFiles = await glob("src/**/*.ts", {
  cwd: "/project",
  ignore: ["node_modules/**", "dist/**"]
});

/**
 * Rename files in a Files collection
 * @param files - Files collection to rename
 * @param renameFn - Function that transforms file names
 * @returns New Files collection with renamed paths
 */
function rename(files: Files, renameFn: (name: string) => string): Files;

import { rename } from "@now/build-utils";

// Add prefix to all files
const prefixedFiles = rename(originalFiles, (name) => `build/${name}`);

// Change file extensions
const renamedFiles = rename(originalFiles, (name) => 
  name.replace(/\.ts$/, ".js")
);

/**
 * Create a writable temporary directory
 * @returns Promise resolving to absolute path to writable directory
 */
function getWriteableDirectory(): Promise<string>;

import { getWriteableDirectory } from "@now/build-utils";

// Create temporary directory for build
const tempDir = await getWriteableDirectory();
console.log("Temp directory:", tempDir);
// Example output: /tmp/7a3f2b1c

/**
 * Convert a readable stream to Buffer
 * @param stream - Node.js readable stream
 * @returns Promise resolving to Buffer containing stream data
 */
function streamToBuffer(stream: NodeJS.ReadableStream): Promise<Buffer>;

/**
 * Check if file mode represents a symbolic link
 * @param mode - File mode number
 * @returns True if the mode represents a symbolic link
 */
function isSymbolicLink(mode: number): boolean;

/**
 * Read and parse configuration file
 * @param files - Single file path or array of file paths to try
 * @returns Promise resolving to parsed configuration or null if not found
 */
function readConfigFile<T>(files: string | string[]): Promise<T | null>;

import { readConfigFile } from "@now/build-utils";

// Try multiple config file names
const config = await readConfigFile([
  'app.json',
  'app.yaml', 
  'app.toml'
]);

if (config) {
  console.log("Found config:", config);
} else {
  console.log("No config file found");
}

// Read specific config file
const packageConfig = await readConfigFile('package.json');

// Standard file permissions
const S_IFMT = 61440;   // 0170000 type of file
const S_IFLNK = 40960;  // 0120000 symbolic link