feat: add min size and empty file validation options (#662)

* feat: add min size and empty file validation options

Author: leonardovillela

README.md

@@ -319,6 +319,10 @@ See it's defaults in [src/Formidable.js](./src/Formidable.js#L14-L22) (the
   placing file uploads in. You can move them later by using `fs.rename()`
 - `options.keepExtensions` **{boolean}** - default `false`; to include the
   extensions of the original files or not
+- `options.allowEmptyFiles` **{boolean}** - default `true`; allow upload empty
+  files
+- `options.minFileSize` **{number}** - default `1` (1byte); the minium size of
+  uploaded file.
 - `options.maxFileSize` **{number}** - default `200 * 1024 * 1024` (200mb);
   limit the size of uploaded file.
 - `options.maxFields` **{number}** - default `1000`; limit the number of fields

src/Formidable.js

@@ -18,6 +18,8 @@ const DEFAULT_OPTIONS = {
   maxFields: 1000,
   maxFieldsSize: 20 * 1024 * 1024,
   maxFileSize: 200 * 1024 * 1024,
+  minFileSize: 1,
+  allowEmptyFiles: true,
   keepExtensions: false,
   encoding: 'utf-8',
   hash: false,
@@ -309,6 +311,14 @@ class IncomingForm extends EventEmitter {
 
     part.on('data', (buffer) => {
       this._fileSize += buffer.length;
+      if (this._fileSize < this.options.minFileSize) {
+        this._error(
+          new Error(
+            `options.minFileSize (${this.options.minFileSize} bytes) inferior, received ${this._fileSize} bytes of file data`,
+          ),
+        );
+        return;
+      }
       if (this._fileSize > this.options.maxFileSize) {
         this._error(
           new Error(
@@ -327,6 +337,15 @@ class IncomingForm extends EventEmitter {
     });
 
     part.on('end', () => {
+      if (!this.options.allowEmptyFiles && this._fileSize === 0) {
+        this._error(
+          new Error(
+            `options.allowEmptyFiles is false, file size should be greather than 0`,
+          ),
+        );
+        return;
+      }
+
       file.end(() => {
         this._flushing -= 1;
         this.emit('file', part.name, file);

test/unit/formidable.test.js

@@ -4,6 +4,7 @@
 'use strict';
 
 const path = require('path');
+const Stream = require('stream');
 // const assert = require('assert');
 const Request = require('http').ClientRequest;
 
@@ -159,6 +160,90 @@ function makeHeader(filename) {
     form.emit('end');
   });
 
+  describe(`${name}#_onPart`, () => {
+    describe('when not allow empty files', () => {
+      describe('when file is empty', () => {
+        test('emits error when part is received', (done) => {
+          const form = getForm(name, {
+            multiples: true,
+            allowEmptyFiles: false,
+          });
+
+          const part = new Stream();
+          part.mime = 'text/plain';
+          // eslint-disable-next-line max-nested-callbacks
+          form.on('error', (error) => {
+            expect(error.message).toBe(
+              'options.allowEmptyFiles is false, file size should be greather than 0',
+            );
+            done();
+          });
+          form.onPart(part);
+          part.emit('end');
+        });
+      });
+
+      describe('when file is not empty', () => {
+        test('not emits error when part is received', () => {
+          const form = getForm(name, {
+            multiples: true,
+            allowEmptyFiles: false,
+          });
+          const formEmitSpy = jest.spyOn(form, 'emit');
+
+          const part = new Stream();
+          part.mime = 'text/plain';
+          form.onPart(part);
+          part.emit('data', Buffer.alloc(1));
+          expect(formEmitSpy).not.toBeCalledWith('error');
+        });
+      });
+    });
+
+    describe('when allow empty files', () => {
+      test('not emits error when part is received', () => {
+        const form = getForm(name, { multiples: true });
+        const formEmitSpy = jest.spyOn(form, 'emit');
+
+        const part = new Stream();
+        part.mime = 'text/plain';
+        form.onPart(part);
+        part.emit('end');
+        expect(formEmitSpy).not.toBeCalledWith('error');
+      });
+    });
+
+    describe('when file uploaded size is inferior than minFileSize option', () => {
+      test('emits error when part is received', (done) => {
+        const form = getForm(name, { multiples: true, minFileSize: 5 });
+
+        const part = new Stream();
+        part.mime = 'text/plain';
+        form.on('error', (error) => {
+          expect(error.message).toBe(
+            'options.minFileSize (5 bytes) inferior, received 4 bytes of file data',
+          );
+          done();
+        });
+        form.onPart(part);
+        part.emit('data', Buffer.alloc(4));
+      });
+    });
+
+    describe('when file uploaded size is superior than minFileSize option', () => {
+      test('not emits error when part is received', () => {
+        const form = getForm(name, { multiples: true, minFileSize: 10 });
+        const formEmitSpy = jest.spyOn(form, 'emit');
+
+        const part = new Stream();
+        part.mime = 'text/plain';
+        form.onPart(part);
+        part.emit('data', Buffer.alloc(11));
+        expect(formEmitSpy).not.toBeCalledWith('error');
+      });
+    });
+  });
+
   // test(`${name}: use custom options.filename instead of form._uploadPath`, () => {
   //   const form = getForm(name, {
   //     filename: (_) => path.join(__dirname, 'sasa'),