feature: disable root path check when serve is false

README.md

@@ -435,9 +435,34 @@ Assume this structure with the compressed asset as a sibling of the un-compresse
 └── index.html
 ```
 
-#### Disable serving
+#### Disable serving and CWD behavior
 
-If you would just like to use the reply decorator and not serve whole directories automatically, you can simply pass the option `{ serve: false }`. This will prevent the plugin from serving everything under `root`.
+If you want to use only the reply decorator without automatically serving whole directories, pass the option `{ serve: false }`. This prevents the plugin from serving everything under `root`.
+
+When `serve: false` is used:
+
+- If no `root` is provided, the plugin will use the current working directory (CWD) as the default root.
+- The `sendFile` method will send files relative to the CWD or the specified `root`.
+
+Example usage:
+
+```js
+const fastify = require('fastify')()
+const path = require('node:path')
+
+fastify.register(require('@fastify/static'), {
+  serve: false,
+  // root is optional when serve is false, will default to CWD if not provided
+  root: path.join(__dirname, 'public')
+})
+
+fastify.get('/file', (req, reply) => {
+  // This will serve the file from the CWD if no root was provided
+  reply.sendFile('myFile.html')
+})
+```
+
+This configuration allows you to use the `sendFile` decorator without automatically serving an entire directory.
 
 #### Disabling reply decorator
 

index.js

@@ -18,8 +18,13 @@ const supportedEncodings = ['br', 'gzip', 'deflate']
 send.mime.default_type = 'application/octet-stream'
 
 async function fastifyStatic (fastify, opts) {
+  if (opts.serve === false && opts.root === undefined) {
+    opts.root = process.cwd()
+    fastify.log.warn('No root path provided. Defaulting to current working directory. This may pose security risks if not intended.')
+  }
+
   opts.root = normalizeRoot(opts.root)
-  checkRootPathForErrors(fastify, opts.root)
+  checkRootPathForErrors(fastify, opts.root, opts.serve === false)
 
   const setHeaders = opts.setHeaders
   if (setHeaders !== undefined && typeof setHeaders !== 'function') {
@@ -408,7 +413,7 @@ function normalizeRoot (root) {
   return root
 }
 
-function checkRootPathForErrors (fastify, rootPath) {
+function checkRootPathForErrors (fastify, rootPath, skipExistenceCheck) {
   if (rootPath === undefined) {
     throw new Error('"root" option is required')
   }
@@ -425,40 +430,46 @@ function checkRootPathForErrors (fastify, rootPath) {
     }
 
     // check each path and fail at first invalid
-    rootPath.map((path) => checkPath(fastify, path))
+    rootPath.map((path) => checkPath(fastify, path, skipExistenceCheck))
     return
   }
 
   if (typeof rootPath === 'string') {
-    return checkPath(fastify, rootPath)
+    return checkPath(fastify, rootPath, skipExistenceCheck)
   }
 
   throw new Error('"root" option must be a string or array of strings')
 }
 
-function checkPath (fastify, rootPath) {
+function checkPath (fastify, rootPath, skipExistenceCheck) {
+  // skip all checks if rootPath is the CWD
+  if (rootPath === process.cwd()) {
+    return
+  }
   if (typeof rootPath !== 'string') {
     throw new Error('"root" option must be a string')
   }
   if (path.isAbsolute(rootPath) === false) {
     throw new Error('"root" option must be an absolute path')
   }
 
-  let pathStat
+  if (!skipExistenceCheck) {
+    let pathStat
 
-  try {
-    pathStat = statSync(rootPath)
-  } catch (e) {
-    if (e.code === 'ENOENT') {
-      fastify.log.warn(`"root" path "${rootPath}" must exist`)
-      return
-    }
+    try {
+      pathStat = statSync(rootPath)
+    } catch (e) {
+      if (e.code === 'ENOENT') {
+        fastify.log.warn(`"root" path "${rootPath}" must exist`)
+        return
+      }
 
-    throw e
-  }
+      throw e
+    }
 
-  if (pathStat.isDirectory() === false) {
-    throw new Error('"root" option must point to a directory')
+    if (pathStat.isDirectory() === false) {
+      throw new Error('"root" option must point to a directory')
+    }
   }
 }
 

test/static.test.js

@@ -4023,3 +4023,76 @@ t.test('content-length in head route should not return zero when using wildcard'
     })
   })
 })
+
+t.test('serve: false disables root path check', t => {
+  t.plan(4)
+
+  t.test('should default to CWD when no root is provided', async (t) => {
+    t.plan(3)
+    const fastify = Fastify()
+
+    let warningLogged = false
+    fastify.log.warn = (message) => {
+      if (message.includes('No root path provided')) {
+        warningLogged = true
+      }
+    }
+
+    await fastify.register(fastifyStatic, { serve: false })
+
+    t.ok(warningLogged, 'should log a warning about defaulting to CWD')
+
+    fastify.get('/test', (req, reply) => {
+      reply.sendFile('test/static/index.html')
+    })
+
+    const response = await fastify.inject('/test')
+    t.equal(response.statusCode, 200, 'should serve file from CWD')
+
+    const fs = require('fs')
+    const expectedContent = fs.readFileSync('test/static/index.html', 'utf8')
+    t.equal(response.payload, expectedContent, 'should serve correct file content')
+  })
+
+  t.test('should not throw when root is non-existent directory and serve is false', async (t) => {
+    t.plan(1)
+    const fastify = Fastify()
+    const nonExistentPath = path.join(__dirname, 'definitely-non-existent-directory')
+
+    await fastify.register(fastifyStatic, {
+      serve: false,
+      root: nonExistentPath
+    })
+    t.pass('should not throw for non-existent directory')
+  })
+
+  t.test('should still validate root is a string or array of strings', async (t) => {
+    t.plan(1)
+    const fastify = Fastify()
+
+    try {
+      await fastify.register(fastifyStatic, {
+        serve: false,
+        root: 123
+      })
+      t.fail('Should have thrown an error for non-string root')
+    } catch (error) {
+      t.match(error.message, /"root" option must be a string or array of strings/, 'Should throw for non-string root')
+    }
+  })
+
+  t.test('should still validate root is an absolute path', async (t) => {
+    t.plan(1)
+    const fastify = Fastify()
+
+    try {
+      await fastify.register(fastifyStatic, {
+        serve: false,
+        root: 'relative/path'
+      })
+      t.fail('Should have thrown an error for relative path')
+    } catch (error) {
+      t.match(error.message, /"root" option must be an absolute path/, 'Should throw for relative path')
+    }
+  })
+})