Add support for OSC 52 clipboard copy in conhost #18949

j4james · 2025-05-26T09:01:16Z

Summary of the Pull Request

This adds support for copying to the clipboard in conhost using the OSC
52 escape sequence, extending the original implementation which was for
Windows Terminal only.

References and Relevant Issues

The Windows Terminal implementation was added in PR #5823.

Detailed Description of the Pull Request / Additional comments

Because the clipboard can't be accessed from a background thread, this
works by saving the content in a global variable, and then posting a
custom message to the main GUI thread, which takes care of the actual
copy operation.

Validation Steps Performed

I've manually confirmed that tmux copy mode is now able to copy to the
system clipboard.

PR Checklist

Closes Add support for OSC 52 clipboard copies in conhost #18943

j4james · 2025-05-26T09:10:06Z

src/host/consoleInformation.cpp

+        // The clipboard can only be updated from the main GUI thread, so we
+        // need to post a message to trigger the actual copy operation. But if
+        // the pending clipboard content is already set, a message would have
+        // already been posted, so there's no need to post another one.
+        const auto clipboardMessageSent = _pendingClipboardText.has_value();
+        _pendingClipboardText = text;
+        if (!clipboardMessageSent)
+        {
+            PostMessageW(window->GetWindowHandle(), CM_UPDATE_CLIPBOARD, 0, 0);
+        }


I don't know if I've just misunderstood how you're supposed to use the windows clipboard, but I couldn't get it working from a background thread, and this technique worked for me. I don't know if maybe there's a better way to do this.

Yep, reading doesn't require a HWND but writing does, to my knowledge.

j4james · 2025-05-26T09:15:47Z

src/interactivity/win32/Clipboard.cpp

+void Clipboard::CopyText(const std::wstring& text)
+{
+    const auto clipboard = _openClipboard(ServiceLocator::LocateConsoleWindow()->GetWindowHandle());
+    if (!clipboard)
+    {
+        LOG_LAST_ERROR();
+        return;
+    }
+
+    EmptyClipboard();
+    // As per: https://learn.microsoft.com/en-us/windows/win32/dataxchg/standard-clipboard-formats
+    //   CF_UNICODETEXT: [...] A null character signals the end of the data.
+    // --> We add +1 to the length. This works because .c_str() is null-terminated.
+    _copyToClipboard(CF_UNICODETEXT, text.c_str(), (text.size() + 1) * sizeof(wchar_t));
+}


The content of this method is copied directly from StoreSelectionToClipboard, but there's really not much to it, so I didn't think there was any point in trying to share the code somehow.

src/host/consoleInformation.cpp

lhecker · 2025-05-26T23:02:44Z

src/host/consoleInformation.cpp

+    const auto clipboardText = _pendingClipboardText;
+    _pendingClipboardText.reset();
+    return clipboardText;


We can avoid a copy here by doing this:

return std::exchange(_pendingClipboardText, {});

I've tested OSC 52 with Windows Terminal with up to 100MiB and it was relatively snappy. So I think avoiding a copy may be useful to reduce the peak memory usage.

...now that I mention this, I realize that immediately copying the clipboard contents into an HGLOBAL would have another benefit... Well, that's a minor issue though.

Thanks for the exchange suggestion. I was hoping there was way to avoid that copy. That's definitely made a difference.

DHowett

Concise and easy to review.

I'm going to attempt to backport this to Ge+ Windows as well. Just to keep the wheels turning. :)

DHowett · 2025-06-10T19:33:45Z

/azp run

azure-pipelines · 2025-06-10T19:33:55Z

Azure Pipelines successfully started running 1 pipeline(s).

## Summary of the Pull Request Some applications that make use of the `OSC 52` clipboard sequence will only do so if they can be certain that the terminal actually has that functionality. Indicating our support for `OSC 52` in the `DA1` report will give them an easy way to detect that. ## References and Relevant Issues `OSC 52` support was added to Windows Terminal in issue #5823, and to ConHost in issue #18949. ## Detailed Description of the Pull Request / Additional comments Support for writing to the clipboard is indicated in the primary device attributes report by the extension parameter `52`. This is obviously not a standard DEC extension, but it's one that's been agreed upon by a number of modern terminals. The extension is only reported when writing to the clipboard is actually permitted (Windows Terminal has an option to disable that). ## Validation Steps Performed I've updated the Device Attributes unit test to check that we're reporting extension `52` when clipboard access is enabled, and not reporting it when disabled. ## PR Checklist - [x] Closes #19017 - [x] Tests added/passed

Some applications that make use of the `OSC 52` clipboard sequence will only do so if they can be certain that the terminal actually has that functionality. Indicating our support for `OSC 52` in the `DA1` report will give them an easy way to detect that. `OSC 52` support was added to Windows Terminal in issue #5823, and to ConHost in issue #18949. Support for writing to the clipboard is indicated in the primary device attributes report by the extension parameter `52`. This is obviously not a standard DEC extension, but it's one that's been agreed upon by a number of modern terminals. The extension is only reported when writing to the clipboard is actually permitted (Windows Terminal has an option to disable that). I've updated the Device Attributes unit test to check that we're reporting extension `52` when clipboard access is enabled, and not reporting it when disabled. - [x] Closes #19017 - [x] Tests added/passed (cherry picked from commit 00ee884) Service-Card-Id: PVTI_lADOAF3p4s4AmhmQzgbpe4k Service-Version: 1.22

## Summary of the Pull Request Some applications that make use of the `OSC 52` clipboard sequence will only do so if they can be certain that the terminal actually has that functionality. Indicating our support for `OSC 52` in the `DA1` report will give them an easy way to detect that. ## References and Relevant Issues `OSC 52` support was added to Windows Terminal in issue #5823, and to ConHost in issue #18949. ## Detailed Description of the Pull Request / Additional comments Support for writing to the clipboard is indicated in the primary device attributes report by the extension parameter `52`. This is obviously not a standard DEC extension, but it's one that's been agreed upon by a number of modern terminals. The extension is only reported when writing to the clipboard is actually permitted (Windows Terminal has an option to disable that). ## Validation Steps Performed I've updated the Device Attributes unit test to check that we're reporting extension `52` when clipboard access is enabled, and not reporting it when disabled. ## PR Checklist - [x] Closes #19017 - [x] Tests added/passed (cherry picked from commit 00ee884) Service-Card-Id: PVTI_lADOAF3p4s4Axadtzgbpe4g Service-Version: 1.23

Add support for OSC 52 clipboard copy in conhost

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j4james commented May 26, 2025

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j4james mentioned this pull request May 26, 2025

Terminal often crashes when typing in a text box using Google Japanese IME #18947

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lhecker reviewed May 26, 2025

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src/host/consoleInformation.cpp Show resolved Hide resolved

lhecker approved these changes May 26, 2025

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Avoid unnecessary string copy

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lhecker approved these changes May 27, 2025

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j4james mentioned this pull request Jun 9, 2025

Indicate support for OSC 52 in the devices attributes report #19017

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DHowett approved these changes Jun 10, 2025

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DHowett added this to Inbox Servicing Pipeline Jun 10, 2025

github-project-automation bot moved this to To Cherry Pick in Inbox Servicing Pipeline Jun 10, 2025

DHowett enabled auto-merge (squash) June 10, 2025 19:34

DHowett merged commit 4abc041 into microsoft:main Jun 10, 2025
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j4james mentioned this pull request Jun 14, 2025

Indicate support for OSC 52 in the DA1 report #19034

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j4james commented May 26, 2025

Summary of the Pull Request

References and Relevant Issues

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

PR Checklist

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