FIX: Better 0 file size detection and logging (#16116)

When creating files with create-multipart, if the file
size was somehow zero we were showing a very unhelpful
error message to the user. Now we show a nicer message,
and proactively don't call the API if we know the file
size is 0 bytes in JS, along with extra console logging
to help with debugging.

app/assets/javascripts/discourse/app/lib/uploads.js

@@ -116,6 +116,13 @@ export function validateUploadedFile(file, opts) {
     }
   }
 
+  if (file.size === 0) {
+    /* eslint-disable no-console */
+    console.warn("File with a 0 byte size detected, cancelling upload.", file);
+    bootbox.alert(I18n.t("post.errors.file_size_zero"));
+    return false;
+  }
+
   // everything went fine
   return true;
 }

app/assets/javascripts/discourse/app/services/media-optimization-worker.js

@@ -42,6 +42,10 @@ export default class MediaOptimizationWorkerService extends Service {
       this.siteSettings
         .composer_media_optimization_image_bytes_optimization_threshold
     ) {
+      this.logIfDebug(
+        `The file ${file.name} was less than the image optimization bytes threshold (${this.siteSettings.composer_media_optimization_image_bytes_optimization_threshold} bytes), skipping.`,
+        file
+      );
       return Promise.resolve();
     }
     await this.ensureAvailableWorker();
@@ -185,10 +189,10 @@ export default class MediaOptimizationWorkerService extends Service {
     this.installPromise = null;
   }
 
-  logIfDebug(message) {
+  logIfDebug(...messages) {
     if (this.siteSettings.composer_media_optimization_debug_mode) {
       // eslint-disable-next-line no-console
-      console.log(message);
+      console.log(...messages);
     }
   }
 }

app/controllers/uploads_controller.rb

@@ -200,6 +200,10 @@ class UploadsController < ApplicationController
   end
 
   def validate_file_size(file_name:, file_size:)
+    if file_size.zero?
+      raise ExternalUploadValidationError.new(I18n.t("upload.size_zero_failure"))
+    end
+
     if file_size_too_big?(file_name, file_size)
       raise ExternalUploadValidationError.new(
         I18n.t(

config/locales/client.en.yml

@@ -3104,6 +3104,7 @@ en:
         edit: "Sorry, there was an error editing your post. Please try again."
         upload: "Sorry, there was an error uploading that file. Please try again."
         file_too_large: "Sorry, that file is too big (maximum size is %{max_size_kb}kb). Why not upload your large file to a cloud sharing service, then paste the link?"
+        file_size_zero: "Sorry, it looks like something has gone wrong, the file you are trying to upload is 0 bytes. Please try again."
         file_too_large_humanized: "Sorry, that file is too big (maximum size is %{max_size}). Why not upload your large file to a cloud sharing service, then paste the link?"
         too_many_uploads: "Sorry, you can only upload one file at a time."
         too_many_dragged_and_dropped_files:

config/locales/server.en.yml

@@ -4088,6 +4088,7 @@ en:
     external_upload_not_found: "The upload was not found in the external store. %{additional_detail}"
     checksum_mismatch_failure: "The checksum of the file you uploaded does not match. The file contents may have changed on upload. Please try again."
     cannot_promote_failure: "The upload cannot be completed, it may have already completed or previously failed."
+    size_zero_failure: "Sorry, it looks like something has gone wrong, the file you are trying to upload is 0 bytes. Please try again."
     attachments:
       too_large: "Sorry, the file you are trying to upload is too big (maximum size is %{max_size_kb}KB)."
       too_large_humanized: "Sorry, the file you are trying to upload is too big (maximum size is %{max_size})."

public/javascripts/media-optimization-worker.js

@@ -25,10 +25,10 @@ function resizeWithAspect(
   };
 }
 
-function logIfDebug(message) {
+function logIfDebug(...messages) {
   if (DedicatedWorkerGlobalScope.debugMode) {
     // eslint-disable-next-line no-console
-    console.log(message);
+    console.log(...messages);
   }
 }
 

spec/requests/uploads_controller_spec.rb

@@ -825,6 +825,22 @@ describe UploadsController do
         expect(response.body).to include(I18n.t("upload.attachments.too_large_humanized", max_size: "1 MB"))
       end
 
+      it 'returns a sensible error if the file size is 0 bytes' do
+        SiteSetting.authorized_extensions = "*"
+        stub_create_multipart_request
+
+        post "/uploads/create-multipart.json", **{
+          params: {
+            file_name: "test.zip",
+            file_size: 0,
+            upload_type: "composer",
+          }
+        }
+
+        expect(response.status).to eq(422)
+        expect(response.body).to include(I18n.t("upload.size_zero_failure"))
+      end
+
       def stub_create_multipart_request
         FileStore::S3Store.any_instance.stubs(:temporary_upload_path).returns(
           "uploads/default/#{test_bucket_prefix}/temp/28fccf8259bbe75b873a2bd2564b778c/test.png"