Normalize document_root() output after realpath() so Page Cache rewrite rules work on Windows

[tivnet]

Util_Environment::document_root() returns the raw output of realpath() at two of its return points without normalizing the directory separators. On Windows realpath() returns back-slashes (and a drive letter), so the returned path does not match the forward-slash-normalized cache directory that other code compares it against. As a result PgCache_Environment::apache_cache_uri_path() fails to relativize the cache path and falls back to the absolute path, producing a broken Disk: Enhanced serve rule.

This makes document_root() consistent with its sibling site_root() in the same file, which already normalizes after realpath().

Symptom (Disk: Enhanced on Windows)

The generated .htaccess serve rule ends up glueing %{DOCUMENT_ROOT} onto an absolute filesystem path, for example:

RewriteCond "%{DOCUMENT_ROOT}C:/path/to/site/wp-content/cache/page_enhanced/%{HTTP_HOST}/.../_index....html" -f

The -f test can never succeed against that path, so every request falls through to PHP (advanced-cache.php) instead of being served statically. Page caching still produces correct files, but the static-serve fast path is silently lost.

Root cause

site_root() normalizes after realpath():

public static function site_root() {
    $site_root = ABSPATH;
    $site_root = realpath( $site_root );
    $site_root = self::normalize_path( $site_root );   // normalized
    return $site_root;
}

document_root() does not - it returns the raw realpath() result. On Windows that value contains back-slashes, so downstream string comparisons against the forward-slash cache directory (in apache_cache_uri_path()) miss, and the code falls back to emitting the absolute path.

Fix

Add self::normalize_path() before each return in document_root(), so the function always returns a forward-slash path regardless of platform - matching site_root().

Testing

• Linux is unaffected: realpath() already returns forward slashes, so normalize_path() is a no-op there and the emitted rewrite rules are unchanged.
• Windows: the emitted Disk: Enhanced serve RewriteCond becomes web-root-relative (%{DOCUMENT_ROOT}/wp-content/cache/page_enhanced/...), and Apache serves the cached file statically.

---

Note

Low Risk
Small, platform-targeted path normalization in environment helpers; Linux paths are unchanged and the change only affects how document root strings are formatted for comparisons and rewrite rules.

Overview
Util_Environment::document_root() now runs normalize_path() on every return path, including after realpath() and on the docroot_fix branch. That aligns it with site_root(), which already normalized post-realpath() output.

On Windows, raw realpath() backslashes broke string comparisons against forward-slash cache paths in Disk: Enhanced rewrite generation (e.g. PgCache_Environment::apache_cache_uri_path()), so .htaccess RewriteCond paths stayed absolute and static serve never matched. Linux behavior is unchanged because normalization is effectively a no-op when paths already use forward slashes.

^{Reviewed by Cursor Bugbot for commit 14aadad. Bugbot is set up for automated code reviews on this repo. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

^{Bugbot Autofix is ON, but it could not run because the branch was deleted or merged before autofix could start.}

Want reviews to match your repository better? Bugbot Learning can learn team-specific rules from PR activity. A team admin can enable Learning in the Cursor dashboard.

^{Reviewed by Cursor Bugbot for commit 14aadad. Configure here.}

[cursor]

CDN path stripping breaks on Windows

Medium Severity

document_root() now always returns a forward-slash path after realpath(), which fixes Page Cache comparisons, but several CDN callers still str_replace that value against OS-native paths such as WP_CONTENT_DIR and upload basedir without normalizing the other side. On Windows those prefixes no longer match, so folder-placeholder and relative-path stripping can leave absolute paths in place.

Additional Locations (1)

• Util_Environment.php#L777-L778

 

^{Reviewed by Cursor Bugbot for commit 14aadad. Configure here.}