Remove base64 encoding from files that contain plain text

app/assets/javascripts/ide/components/new_dropdown/upload.vue

@@ -25,14 +25,32 @@ export default {
     },
   },
   methods: {
-    createFile(target, file, isText) {
+    isText(content, fileType) {
+      const knownBinaryFileTypes = ['image/'];
+      const knownTextFileTypes = ['text/'];
+      const isKnownBinaryFileType = knownBinaryFileTypes.find(type => fileType.includes(type));
+      const isKnownTextFileType = knownTextFileTypes.find(type => fileType.includes(type));
+      const asciiRegex = /^[ -~\t\n\r]+$/; // tests whether a string contains ascii characters only (ranges from space to tilde, tabs and new lines)
+
+      if (isKnownBinaryFileType) {
+        return false;
+      }
+
+      if (isKnownTextFileType) {
+        return true;
+      }
+
+      // if it's not a known file type, determine the type by evaluating the file contents
+      return asciiRegex.test(content);
+    },
+    createFile(target, file) {
       const { name } = file;
       let { result } = target;
+      const encodedContent = result.split('base64,')[1];
+      const rawContent = encodedContent ? atob(encodedContent) : '';
+      const isText = this.isText(rawContent, file.type);
 
-      if (!isText) {
-        // eslint-disable-next-line prefer-destructuring
-        result = result.split('base64,')[1];
-      }
+      result = isText ? rawContent : encodedContent;
 
       this.$emit('create', {
         name: `${this.path ? `${this.path}/` : ''}${name}`,
@@ -43,15 +61,9 @@ export default {
     },
     readFile(file) {
       const reader = new FileReader();
-      const isText = file.type.match(/text.*/) !== null;
 
-      reader.addEventListener('load', e => this.createFile(e.target, file, isText), { once: true });
-
-      if (isText) {
-        reader.readAsText(file);
-      } else {
+      reader.addEventListener('load', e => this.createFile(e.target, file), { once: true });
       reader.readAsDataURL(file);
-      }
     },
     openFile() {
       Array.from(this.$refs.fileUpload.files).forEach(file => this.readFile(file));

changelogs/unreleased/fix-base64-encoded-file-uploads.yml

+---
+title: Remove base64 encoding from files that contain plain text
+merge_request: 22425
+author:
+type: fixed

spec/javascripts/ide/components/new_dropdown/upload_spec.js

@@ -40,21 +40,10 @@ describe('new dropdown upload', () => {
 
   describe('readFile', () => {
     beforeEach(() => {
-      spyOn(FileReader.prototype, 'readAsText');
       spyOn(FileReader.prototype, 'readAsDataURL');
     });
 
-    it('calls readAsText for text files', () => {
-      const file = {
-        type: 'text/html',
-      };
-
-      vm.readFile(file);
-
-      expect(FileReader.prototype.readAsText).toHaveBeenCalledWith(file);
-    });
-
-    it('calls readAsDataURL for non-text files', () => {
+    it('calls readAsDataURL for all files', () => {
       const file = {
         type: 'images/png',
       };
@@ -66,32 +55,37 @@ describe('new dropdown upload', () => {
   });
 
   describe('createFile', () => {
-    const target = {
-      result: 'content',
+    const textTarget = {
+      result: 'base64,cGxhaW4gdGV4dA==',
     };
     const binaryTarget = {
-      result: 'base64,base64content',
+      result: 'base64,w4I=',
     };
-    const file = {
-      name: 'file',
+    const textFile = {
+      name: 'textFile',
+      type: 'text/plain',
+    };
+    const binaryFile = {
+      name: 'binaryFile',
+      type: 'image/png',
     };
 
-    it('creates new file', () => {
-      vm.createFile(target, file, true);
+    it('creates file in plain text (without encoding) if the file content is plain text', () => {
+      vm.createFile(textTarget, textFile);
 
       expect(vm.$emit).toHaveBeenCalledWith('create', {
-        name: file.name,
+        name: textFile.name,
         type: 'blob',
-        content: target.result,
+        content: 'plain text',
         base64: false,
       });
     });
 
     it('splits content on base64 if binary', () => {
-      vm.createFile(binaryTarget, file, false);
+      vm.createFile(binaryTarget, binaryFile);
 
       expect(vm.$emit).toHaveBeenCalledWith('create', {
-        name: file.name,
+        name: binaryFile.name,
         type: 'blob',
         content: binaryTarget.result.split('base64,')[1],
         base64: true,