Fix backslash character stripping in Copy Post module

[Copilot]

Fixes #46020

Proposed changes:

Backslash characters (\) were being stripped from post content when duplicating posts. For example, \t is a tab became t is a tab.

Root cause: wp_update_post() internally calls wp_unslash(), expecting slashed data (like from $_POST). When passing unslashed database data directly, backslashes get stripped.

Fix: Wrap data with wp_slash() before passing to wp_update_post(), matching the pattern in WordPress Core's wp_restore_post_revision() (revision.php:485).

Changes:

• copy-post.php: Add wp_slash() in update_content()

// Before
return wp_update_post( $data );

// After  
return wp_update_post( wp_slash( $data ) );

Other information:

• [x] Have you written new tests for your changes, if applicable?
• [ ] Have you checked the E2E test CI results, and verified that your changes do not break them?
• [ ] Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

Does this pull request change what data or activity we track or use?

No.

Testing instructions:

• Create a post with a Code block containing \t is a tab
• Save the post
• Click "Duplicate" from post actions
• Verify the duplicated post retains \t is a tab (not t is a tab)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Copy post strips "" characters from post content</issue_title> <issue_description>### Impacted plugin

Jetpack

Quick summary

The "copy post" or "duplicate post" functionality may incorrectly strip the \ character from post content.

This affected character is U+005C Reverse Solidus character or "backslash."

Steps to reproduce

1. Create a post with content like this:

   <!-- wp:code -->
   <pre class="wp-block-code"><code>\t is a tab</code></pre>
   <!-- /wp:code -->
   

   That is a Code block with the text \t is a tab.

2. Save the post.

3. From the post edit view, click "Duplicate" on the post.

4. A post is created where the text is now t is a tab:

   <!-- wp:code -->
   <pre class="wp-block-code"><code>t is a tab</code></pre>
   <!-- /wp:code -->
   

 <!-- wp:code -->
-<pre class="wp-block-code"><code>\t is a tab</code></pre>
+<pre class="wp-block-code"><code>t is a tab</code></pre>
 <!-- /wp:code -->

This seems to happen regularly with the \ character:

• \t -> t
• \n -> n
• \f -> f
• \\ -> \
• \9 -> 9
• \ -> (space)

[!NOTE] The reproduction uses a Code block because it's easy to see the characters, but this seems to happen on any content. Text in a Paragraph block will also be affected.

Site owner impact

Fewer than 20% of the total website/platform users

Severity

Minor

What other impact(s) does this issue have?

No response

If a workaround is available, please outline it here.

No response

Platform (Simple and/or Atomic)

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Automattic/jetpack#46020

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[sirreal]

@copilot You should look at this history: https://github.com/Automattic/jetpack/pull/1703

[Copilot]

@copilot You should look at this history: https://github.com/Automattic/jetpack/pull/1703

Thanks for sharing that context. I reviewed the history and see that PR #1703's fix was reverted because it modified the transform() and swap_for_editing() methods - core markdown transformation logic.

My changes are different in scope - I'm only adding wp_slash() wrappers in wp_restore_post_revision() and fix_latest_revision_on_restore() before calling wp_update_post()/wp_insert_post(). This follows the same pattern used in WordPress Core's wp_restore_post_revision() (revision.php:485).

The copy-post.php change is straightforward and safe. For the markdown module changes, the context is narrower - we're just ensuring DB data is properly slashed before passing to these WordPress functions, not modifying the transformation pipeline that caused issues in the old PR.

That said, given the module's complexity, if you'd prefer I revert the markdown changes and keep only the copy-post fix, let me know.

[sirreal]

That said, given the module's complexity, if you'd prefer I revert the markdown changes and keep only the copy-post fix, let me know.

@copilot Since this appears to be a separate issue, you should create a separate PR for that and remove the changes from this PR.

[Copilot]

That said, given the module's complexity, if you'd prefer I revert the markdown changes and keep only the copy-post fix, let me know.

@copilot Since this appears to be a separate issue, you shoul...

Removed the markdown module changes in a803166. This PR now only contains the copy-post fix.

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