1695659 - Inconsistent document.execCommand('paste') behaviour in tabs with iframes

Status: NEW

(WebExtensions :: General, defect, P3)

Description

[erosman]

Firefox 88.0a1 (2021-03-01) (64-bit) Win7

Info

• activeTab permission
• paste into textarea, input and contenteditable
• Pasting from clipboard into above on context-menu onclick
• same origin file:///C:/Users/.... in test
• using tabs.executeScript() to inject
• Injection into all applicable frames are confirmed
• there are no errors
• document.execCommand('paste') returns true when works and returns false when it fails

Testing on 2 HTML pages

• An HTML page with input, textarea & contenteditable elements
• As above plus an iframe that also has input, textarea & contenteditable elements

Also tested on random web pages.

allFrames: false

const code = `(() => document.execCommand('paste'))();`;
chrome.tabs.executeScript({code}, (result = []) => {
  console.log(result);
});

Result

• tab with 1 frame: ✅ paste works in top-frame // Array [ true ]
• tab with 1+ frames: ❌ paste fails in top-frame // Array [ false ]
• tab with 1+ frames: ❌ paste fails in sub-frame // Array [ false ]

allFrames: true

const code = `(() => document.execCommand('paste'))();`;
chrome.tabs.executeScript({code, allFrames: true}, (result = []) => {
  console.log(result);
});

Result

• tab with 1 frame: ✅ paste works in top-frame // Array [ true ]
• tab with 1+ frames: ❌ paste fails in top-frame // Array [ false, true ]
• tab with 1+ frames: ✅ paste works in sub-frame // Array [ false, true ]

Result Summary
The behaviour of document.execCommand('paste') appears to be inconsistent when there are more than one frames in a tab.

Comment 1

[erosman]

Attachment: 1695659.zip

Bug 1695659 minimal test extension

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

Does this happen with an extension only or is there some testcase showing the issue also in web pages?

Comment 3

[erosman]

I am not sure how to test it in a web page and into top-frame as well as sub-frames and trigger it from a user-action while keeping the document.activeElement the target of the paste.

Comment 4

[Tomislav Jovanovic :zombie]

Tomislav wants to investigate.