Strings in the system clipboard contain trailing NULL character

Linux
1

JUCE: v5.4.7
OS: Debian GNU/Linux 10 (buster)
X.Org version: 1.20.4

Using the SytemClipboard class like this:

SystemClipboard::copyTextToClipboard ("test");

and then pasting the clipboard content somewhere else (e.g. a text editor) results in the following string:

test�

The trailing symbol is the NULL unicode character (U+0000). It looks like the null character is not properly stripped off when the string is passed to the X11 clipboard system.

1 Like
2

Upon further investigation, the NULL character is not present on Ubuntu 18.04, with X.Org version 1.20.8.
I managed to fix the glitch with by applying the following changes:

--- a/modules/juce_gui_basics/native/juce_linux_X11_Clipboard.cpp
+++ b/modules/juce_gui_basics/native/juce_linux_X11_Clipboard.cpp
@@ -154,9 +154,9 @@ namespace ClipboardHelpers
             if (evt.target == XA_STRING || evt.target == ClipboardHelpers::atom_UTF8_STRING)
             {
                 // translate to utf8
-                numDataItems = ClipboardHelpers::localClipboardContent.getNumBytesAsUTF8() + 1;
+                numDataItems = ClipboardHelpers::localClipboardContent.getNumBytesAsUTF8();
                 data.calloc (numDataItems + 1);
-                ClipboardHelpers::localClipboardContent.copyToUTF8 (data, numDataItems);
+                ClipboardHelpers::localClipboardContent.copyToUTF8 (data, numDataItems + 1);
                 propertyFormat = 8; // bits/item
             }
             else if (evt.target == ClipboardHelpers::atom_TARGETS)

Tested both on the original system (Debian 10 with X.Org version: 1.20.4) and Ubuntu.

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3

I’m unable to reproduce this on Debian 10 or Ubuntu 18.04 using X11 v1.20.4. Can you check and see if the issue is still present in the latest version of JUCE?

4

Just tested with JUCE 6.0.1 on Debian 10 (buster), X version: 1.20.4: I still can reproduce the problem.

However I’ve noticed something more: the NULL character doesn’t show up if you copy and paste the text within the same JUCE app - e.g. I tried with the Projucer (both 5.x and 6.0.1) and I could copy/paste text flawlessly.

5

Where are you pasting to where you are seeing the null character? I’ve tried pasting to other non-JUCE apps like the system Text Editor and it looks correct.

6

I’m pasting it on a new document in Visual Studio Code, in the Chrome address bar and also in the text area right here on this forum.

7

Thanks, I see what’s happening now. String::getNumBytesAsUTF8() returns the number of bytes excluding the null-terminator so we’re adding 1 to it. but then also allocating an extra byte for data on the line below.

This has been fixed on the develop branch:

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