FileWriter silently fails in IFrame with 'Invalid Parameter type'

[wehe64]

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Bug Report:

FileWriter silently fails in IFrame with 'Invalid Parameter type'

Problem

A blob/pdf is written to a temporary file on the device and then opened via the platform's OS. This workes fine when the test-doc is properly compiled into its own platform app on Android or iOS.

But I want my app to come empty and be installed without it's content document, which should be downloaded and locally stored by the final user only.

When the test-doc is downloaded by a loader-app, then written to the device storage and displayed from there in an IFrame, everything looks and works fine, except this:

• When the doc's JS creates a FileWriter, all looks good, but no data gets written. No Error occurs and the empty file is passed on to the file-opener2 and finally the PDF-viewer complains about the corrupt pdf.

On iOS the console shows an error inside the FileWriter object, on Android, no errors are reported at all.

What is expected to happen?

• LoaderApp started, then loades & stores the loaderDoc web-document,
• the loaderDoc should be able to download, store, open and display a test-PDF from Github.

What does actually happen?

• pdf file size always empty (or just 2bytes)
• no errors in console on Android
• on iOS in console:
  FileWriter error: 'Invalid Parameter type'

Information

the cordova loaderDoc project

• can either run as is (w/o the LoaderApp) - and works fine
• or be payload for the LoaderApp, that is:
  • have its www-folder downloaded as zip,
  • be stored locally on the device
  • and then opened from there in an IFrame
  • in both cases the same code runs -
    in the latter case it fails

DROP-IN www/cordova.js:

www/cordova.js of the payload document is meant to be replaced during cordova's build procress.

In two cases it won't be replaced and is used as is:

• before the raw web-doc is put inside a cordova project's www/ folder (happens on the CMS creating the doc)
• if it resides in the LoaderApp's IFrame, in this case proxies of the plugins are created inside the IFrame

Command or Code

1. build the loaderDoc as a cordova app, install/run it,
   see if it manages to download, write and open the test-pdf
2. build and run the LoaderApp, have it download the loaderDoc, save and open it, and finally have the loaderDoc fail its test-operation.

Environment, Platform, Device

Desktop Linux:

5.8.6-1-MANJARO, x86_64 GNU/Linux

Desktop OS/X:

Systemversion:	macOS 10.15.6 (19G2021)
Kernel-Version:	Darwin 19.6.0

Android:

Galaxy Tab-A Model SM-T510
Android-Version: 10
Kernel-Version: 4.4.177-19000394
# 1 Tue June 30 16:25:20 KST 2020

iOS:

iPAD Air 2
iOS-Version 14.0
ModelNo MGHY2FD/A

Version information

for both LoaderApp and and the loaderDoc:

> cordova --version
10.0.0

> cordova platform ls
Installed platforms:
  android 9.0.0
  ios 6.1.1

> cordova plugin ls
cordova-plugin-device 2.0.3 "Device"
cordova-plugin-dialogs 2.0.2 "Notification"
cordova-plugin-file-opener2 3.0.5 "File Opener2"
cordova-plugin-file 6.0.2 "File"
cordova-plugin-whitelist 1.3.4 "Whitelist"

- jQuery 3.5.1.min.js
- jszip.min.js

Android Studio 4.0.1
Build #AI-193.6911.18.40.6626763, built on June 25, 2020
Runtime version: 1.8.0_242-release-1644-b3-6222593 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Linux 5.8.6-1-MANJARO
GC: ParNew, ConcurrentMarkSweep
Memory: 1981M
Cores: 8
Registry: ide.new.welcome.screen.force=true
Non-Bundled Plugins: org.jetbrains.kotlin, com.google.services.firebase

Checklist

• [x] I searched for existing GitHub issues
• [x] I updated all Cordova tooling to most recent version
• [x] I included all the necessary information above