file-entry-cache

Table of Contents

file-entry-cache

A lightweight cache for file metadata, ideal for processes that work on a specific set of files and only need to reprocess files that have changed since the last run

codecov tests npm npm license

Features

  • Lightweight cache for file metadata
  • Ideal for processes that work on a specific set of files
  • Persists cache to Disk via reconcile() or persistInterval on cache options.
  • Uses checksum to determine if a file has changed
  • Supports relative and absolute paths with configurable current working directory
  • Portable cache files when using relative paths
  • ESM and CommonJS support with Typescript

Table of Contents

Installation

npm install file-entry-cache

Getting Started

import fileEntryCache from 'file-entry-cache';
const cache = fileEntryCache.create('cache1');

// Using relative paths
let fileDescriptor = cache.getFileDescriptor('./src/file.txt');
console.log(fileDescriptor.changed); // true as it is the first time
console.log(fileDescriptor.key); // './src/file.txt' (stored as provided)

fileDescriptor = cache.getFileDescriptor('./src/file.txt');
console.log(fileDescriptor.changed); // false as it has not changed

// do something to change the file
fs.writeFileSync('./src/file.txt', 'new data foo bar');

// check if the file has changed
fileDescriptor = cache.getFileDescriptor('./src/file.txt');
console.log(fileDescriptor.changed); // true

Save it to Disk and Reconcile files that are no longer found

import fileEntryCache from 'file-entry-cache';
const cache = fileEntryCache.create('cache1');
let fileDescriptor = cache.getFileDescriptor('./src/file.txt');
console.log(fileDescriptor.changed); // true as it is the first time
cache.reconcile(); // save the cache to disk and remove files that are no longer found

Load the cache from a file:

import fileEntryCache from 'file-entry-cache';
const cache = fileEntryCache.createFromFile('/path/to/cache/file');
let fileDescriptor = cache.getFileDescriptor('./src/file.txt');
console.log(fileDescriptor.changed); // false as it has not changed from the saved cache.

Changes from v10 to v11

BREAKING CHANGES:

  • strictPaths now defaults to true - Path traversal protection is enabled by default for security. To restore v10 behavior, explicitly set strictPaths: false

NEW FEATURES:

  • Added cwd option - You can now specify a custom current working directory for resolving relative paths
  • Added strictPaths option - Provides protection against path traversal attacks (enabled by default)
  • Improved cache portability - When using relative paths with the same cwd, cache files are portable across different environments

Changes from v9 to v10

There have been many features added and changes made to the file-entry-cache class. Here are the main changes:

  • Added cache object to the options to allow for more control over the cache
  • Added hashAlgorithm to the options to allow for different checksum algorithms. Note that if you load from file it most likely will break if the value was something before.
  • Migrated to Typescript with ESM and CommonJS support. This allows for better type checking and support for both ESM and CommonJS.
  • Once options are passed in they get assigned as properties such as hashAlgorithm. For the Cache options they are assigned to cache such as cache.ttl and cache.lruSize.
  • Added cache.persistInterval to allow for saving the cache to disk at a specific interval. This will save the cache to disk at the interval specified instead of calling reconsile() to save. (off by default)
  • Added getFileDescriptorsByPath(filePath: string): FileEntryDescriptor[] to get all the file descriptors that start with the path specified. This is useful when you want to get all the files in a directory or a specific path.
  • Using flat-cache v6 which is a major update. This allows for better performance and more control over the cache.
  • On FileEntryDescriptor.meta if using typescript you need to use the meta.data to set additional information. This is to allow for better type checking and to avoid conflicts with the meta object which was any.

Global Default Functions

  • create(cacheId: string, cacheDirectory?: string, useCheckSum?: boolean, cwd?: string) - Creates a new instance of the FileEntryCache class
  • createFromFile(cachePath: string, useCheckSum?: boolean, cwd?: string) - Creates a new instance of the FileEntryCache class and loads the cache from a file.

FileEntryCache Options (FileEntryCacheOptions)

  • useModifiedTime? - If true it will use the modified time to determine if the file has changed. Default is true
  • useCheckSum? - If true it will use a checksum to determine if the file has changed. Default is false
  • hashAlgorithm? - The algorithm to use for the checksum. Default is md5 but can be any algorithm supported by crypto.createHash
  • cwd? - The current working directory for resolving relative paths. Default is process.cwd()
  • strictPaths? - If true restricts file access to within cwd boundaries, preventing path traversal attacks. Default is true
  • cache.ttl? - The time to live for the cache in milliseconds. Default is 0 which means no expiration
  • cache.lruSize? - The number of items to keep in the cache. Default is 0 which means no limit
  • cache.useClone? - If true it will clone the data before returning it. Default is false
  • cache.expirationInterval? - The interval to check for expired items in the cache. Default is 0 which means no expiration
  • cache.persistInterval? - The interval to save the data to disk. Default is 0 which means no persistence
  • cache.cacheDir? - The directory to save the cache files. Default is ./cache
  • cache.cacheId? - The id of the cache. Default is cache1
  • cache.parse? - The function to parse the data. Default is flatted.parse
  • cache.stringify? - The function to stringify the data. Default is flatted.stringify

API

  • constructor(options?: FileEntryCacheOptions) - Creates a new instance of the FileEntryCache class
  • useCheckSum: boolean - If true it will use a checksum to determine if the file has changed. Default is false
  • hashAlgorithm: string - The algorithm to use for the checksum. Default is md5 but can be any algorithm supported by crypto.createHash
  • getHash(buffer: Buffer): string - Gets the hash of a buffer used for checksums
  • cwd: string - The current working directory for resolving relative paths. Default is process.cwd()
  • strictPaths: boolean - If true restricts file access to within cwd boundaries. Default is true
  • createFileKey(filePath: string): string - Returns the cache key for the file path (returns the path exactly as provided).
  • deleteCacheFile(): boolean - Deletes the cache file from disk
  • destroy(): void - Destroys the cache. This will clear the cache in memory. If using cache persistence it will stop the interval.
  • removeEntry(filePath: string): void - Removes an entry from the cache.
  • reconcile(): void - Saves the cache to disk and removes any files that are no longer found.
  • hasFileChanged(filePath: string): boolean - Checks if the file has changed. This will return true if the file has changed.
  • getFileDescriptor(filePath: string, options?: { useModifiedTime?: boolean, useCheckSum?: boolean }): FileEntryDescriptor - Gets the file descriptor for the file. Please refer to the entire section on Get File Descriptor for more information.
  • normalizeEntries(files?: string[]): FileDescriptor[] - Normalizes the entries. If no files are provided, it will return all cached entries.
  • analyzeFiles(files: string[]) will return AnalyzedFiles object with changedFiles, notFoundFiles, and notChangedFiles as FileDescriptor arrays.
  • getUpdatedFiles(files: string[]) will return an array of FileEntryDescriptor objects that have changed.
  • getFileDescriptorsByPath(filePath: string): FileEntryDescriptor[] will return an array of FileEntryDescriptor objects that starts with the path prefix specified.
  • getAbsolutePath(filePath: string): string - Resolves a relative path to absolute using the configured cwd. Returns absolute paths unchanged. When strictPaths is enabled, throws an error if the path resolves outside cwd.
  • getAbsolutePathWithCwd(filePath: string, cwd: string): string - Resolves a relative path to absolute using a custom working directory. When strictPaths is enabled, throws an error if the path resolves outside the provided cwd.

Get File Descriptor

The getFileDescriptor(filePath: string, options?: { useCheckSum?: boolean, useModifiedTime?: boolean }): FileEntryDescriptor function is used to get the file descriptor for the file. This function will return a FileEntryDescriptor object that has the following properties:

  • key: string - The cache key for the file. This is exactly the path that was provided (relative or absolute).
  • changed: boolean - If the file has changed since the last time it was analyzed.
  • notFound: boolean - If the file was not found.
  • meta: FileEntryMeta - The meta data for the file. This has the following properties: size, mtime, hash, data. Note that data is an object that can be used to store additional information.
  • err - If there was an error analyzing the file.

Path Handling and Current Working Directory

The cache stores paths exactly as they are provided (relative or absolute). When checking if files have changed, relative paths are resolved using the configured cwd (current working directory):

// Default: uses process.cwd()
const cache1 = fileEntryCache.create('cache1');

// Custom working directory
const cache2 = fileEntryCache.create('cache2', './cache', false, '/project/root');
// Or with options object
const cache3 = new FileEntryCache({ cwd: '/project/root' });

// The cache key is always the provided path
const descriptor = cache2.getFileDescriptor('./src/file.txt');
console.log(descriptor.key); // './src/file.txt'
// But file operations resolve from: '/project/root/src/file.txt'

Cache Portability

Using relative paths with a consistent cwd (defaults to process.cwd()) makes cache files portable across different machines and environments. This is especially useful for CI/CD pipelines and team development.

// On machine A (project at /home/user/project)
const cacheA = fileEntryCache.create('build-cache', './cache', false, '/home/user/project');
cacheA.getFileDescriptor('./src/index.js'); // Resolves to /home/user/project/src/index.js
cacheA.reconcile();

// On machine B (project at /workspace/project)
const cacheB = fileEntryCache.create('build-cache', './cache', false, '/workspace/project');
cacheB.getFileDescriptor('./src/index.js'); // Resolves to /workspace/project/src/index.js
// Cache hit! File hasn't changed since machine A

Maximum Portability with Checksums

For maximum cache portability across different environments, use checksums (useCheckSum: true) along with relative paths and cwd which defaults to process.cwd(). This ensures that cache validity is determined by file content rather than modification times, which can vary across systems:

// Development machine
const devCache = fileEntryCache.create(
    '.buildcache',
    './cache',                 // cache directory
    true                      // Use checksums for content-based comparison
);

// Process files using relative paths
const descriptor = devCache.getFileDescriptor('./src/index.js');
if (descriptor.changed) {
    console.log('Building ./src/index.js...');
    // Build process here
}
devCache.reconcile(); // Save cache

// CI/CD Pipeline or another developer's machine
const ciCache = fileEntryCache.create(
    '.buildcache',
    './node_modules/.cache',
    true,                      // Same checksum setting
    process.cwd()              // Different absolute path, same relative structure
);

// Same relative path works across environments
const descriptor2 = ciCache.getFileDescriptor('./src/index.js');
if (!descriptor2.changed) {
    console.log('Using cached result for ./src/index.js');
    // Skip rebuild - file content unchanged
}

Handling Project Relocations

Cache remains valid even when projects are moved or renamed:

// Original location: /projects/my-app
const cache1 = fileEntryCache.create('.cache', './cache', true, '/projects/my-app');
cache1.getFileDescriptor('./src/app.js');
cache1.reconcile();

// After moving project to: /archived/2024/my-app
const cache2 = fileEntryCache.create('.cache', './cache', true, '/archived/2024/my-app');
cache2.getFileDescriptor('./src/app.js'); // Still finds cached entry!
// Cache valid as long as relative structure unchanged

If there is an error when trying to get the file descriptor it will return a notFound and err property with the error.

const fileEntryCache = new FileEntryCache();
const fileDescriptor = fileEntryCache.getFileDescriptor('no-file');
if (fileDescriptor.err) {
    console.error(fileDescriptor.err);
}

if (fileDescriptor.notFound) {
    console.error('File not found');
}

Path Security and Traversal Prevention

The strictPaths option provides security against path traversal attacks by restricting file access to within the configured cwd boundaries. This is enabled by default (since v11) to ensure secure defaults when processing untrusted input or when running in security-sensitive environments.

Basic Usage

// strictPaths is enabled by default for security
const cache = new FileEntryCache({
    cwd: '/project/root'
});

// This will work - file is within cwd
const descriptor = cache.getFileDescriptor('./src/index.js');

// This will throw an error - attempts to access parent directory
try {
    cache.getFileDescriptor('../../../etc/passwd');
} catch (error) {
    console.error(error); // Path traversal attempt blocked
}

// To allow parent directory access (not recommended for untrusted input)
const unsafeCache = new FileEntryCache({
    cwd: '/project/root',
    strictPaths: false  // Explicitly disable protection
});

Security Features

When strictPaths is enabled:

  • Path Traversal Prevention: Blocks attempts to access files outside the working directory using ../ sequences
  • Null Byte Protection: Automatically removes null bytes from paths to prevent injection attacks
  • Path Normalization: Cleans and normalizes paths to prevent bypass attempts

Use Cases

Build Tools with Untrusted Input

// Secure build tool configuration
const cache = fileEntryCache.create(
    '.buildcache',
    './cache',
    true,  // useCheckSum
    process.cwd()
);

// Enable strict path checking for security
cache.strictPaths = true;

// Process user-provided file paths safely
function processUserFile(userProvidedPath) {
    try {
        const descriptor = cache.getFileDescriptor(userProvidedPath);
        // Safe to process - file is within boundaries
        return descriptor;
    } catch (error) {
        if (error.message.includes('Path traversal attempt blocked')) {
            console.warn('Security: Blocked access to:', userProvidedPath);
            return null;
        }
        throw error;
    }
}

CI/CD Environments

// Strict security for CI/CD pipelines
const cache = new FileEntryCache({
    cwd: process.env.GITHUB_WORKSPACE || process.cwd(),
    strictPaths: true,  // Prevent access outside workspace
    useCheckSum: true   // Content-based validation
});

// All file operations are now restricted to the workspace
cache.getFileDescriptor('./src/app.js');  // ✓ Allowed
cache.getFileDescriptor('/etc/passwd');   // ✗ Blocked (absolute path outside cwd)
cache.getFileDescriptor('../../../root'); // ✗ Blocked (path traversal)

Dynamic Security Control

const cache = new FileEntryCache({ cwd: '/safe/directory' });

// Start with relaxed mode for trusted operations
cache.strictPaths = false;
processInternalFiles();

// Enable strict mode for untrusted input
cache.strictPaths = true;
processUserUploadedPaths();

// Return to relaxed mode if needed
cache.strictPaths = false;

Default Behavior

As of v11, strictPaths is enabled by default to provide secure defaults. This means:

  • Path traversal attempts using ../ are blocked
  • File access is restricted to within the configured cwd
  • Null bytes in paths are automatically sanitized

Migrating from v10 or Earlier

If you're upgrading from v10 or earlier and need to maintain the previous behavior (for example, if your code legitimately accesses parent directories), you can explicitly disable strict paths:

const cache = new FileEntryCache({
    cwd: process.cwd(),
    strictPaths: false  // Restore v10 behavior
});

However, we strongly recommend keeping strictPaths: true and adjusting your code to work within the security boundaries, especially when processing any untrusted input.

Using Checksums to Determine if a File has Changed (useCheckSum)

By default the useCheckSum is false. This means that the FileEntryCache will use the mtime and ctime to determine if the file has changed. If you set useCheckSum to true it will use a checksum to determine if the file has changed. This is useful when you want to make sure that the file has not changed at all.

const fileEntryCache = new FileEntryCache();
const fileDescriptor = fileEntryCache.getFileDescriptor('file.txt', { useCheckSum: true });

You can pass useCheckSum in the FileEntryCache options, as a property .useCheckSum to make it default for all files, or in the getFileDescriptor function. Here is an example where you set it globally but then override it for a specific file:

const fileEntryCache = new FileEntryCache({ useCheckSum: true });
const fileDescriptor = fileEntryCache.getFileDescriptor('file.txt', { useCheckSum: false });

Setting Additional Meta Data

In the past we have seen people do random values on the meta object. This can cause issues with the meta object. To avoid this we have data which can be anything.

const fileEntryCache = new FileEntryCache();
const fileDescriptor = fileEntryCache.getFileDescriptor('file.txt');
fileDescriptor.meta.data = { myData: 'myData' }; //anything you want

How to Contribute

You can contribute by forking the repo and submitting a pull request. Please make sure to add tests and update the documentation. To learn more about how to contribute go to our main README https://github.com/jaredwray/cacheable. This will talk about how to Open a Pull Request, Ask a Question, or Post an Issue.

License and Copyright

MIT © Jared Wray