Refactor webroot detection in resource locator

The current implementation breaks installations with symlinks to
directories inside the webroot (i.E. apps).

With this change both variants, directory and symlinks, will be detected
correctly.

Fixes: #6028
Signed-off-by: Axel Helmert <axel.helmert@luka.de>

2 files changed, 68 insertions, 64 deletions

diff --git a/lib/private/Template/CSSResourceLocator.php b/lib/private/Template/CSSResourceLocator.php
index 32dabb48c0d..1b4050e4ae0 100644
--- a/lib/private/Template/CSSResourceLocator.php
+++ b/lib/private/Template/CSSResourceLocator.php
@@ -117,38 +117,18 @@ class CSSResourceLocator extends ResourceLocator {
 			parent::append($root, $file, $webRoot, $throw);
 		} else {
 			if (!$webRoot) {
-				$tmpRoot = realpath($root);
-				/*
-				 * traverse the potential web roots upwards in the path
-				 *
-				 * example:
-				 *   - root: /srv/www/apps/myapp
-				 *   - available mappings: ['/srv/www']
-				 *
-				 * First we check if a mapping for /srv/www/apps/myapp is available,
-				 * then /srv/www/apps, /srv/www/apps, /srv/www, ... until we find a
-				 * valid web root
-				 */
-				do {
-					if (isset($this->mapping[$tmpRoot])) {
-						$webRoot = $this->mapping[$tmpRoot];
-						break;
-					}
-
-					if ($tmpRoot === '/') {
-						$webRoot = '';
-						$this->logger->error('ResourceLocator can not find a web root (root: {root}, file: {file}, webRoot: {webRoot}, throw: {throw})', [
-							'app' => 'lib',
-							'root' => $root,
-							'file' => $file,
-							'webRoot' => $webRoot,
-							'throw' => $throw ? 'true' : 'false'
-						]);
-						break;
-					}
-					$tmpRoot = dirname($tmpRoot);
-				} while(true);
-
+				$webRoot = $this->findWebRoot($root);
+
+				if (!$webRoot) {
+					$webRoot = '';
+					$this->logger->error('ResourceLocator can not find a web root (root: {root}, file: {file}, webRoot: {webRoot}, throw: {throw})', [
+						'app' => 'lib',
+						'root' => $root,
+						'file' => $file,
+						'webRoot' => $webRoot,
+						'throw' => $throw ? 'true' : 'false'
+					]);
+				}
 			}
 
 			if ($throw && $tmpRoot === '/') {
diff --git a/lib/private/Template/ResourceLocator.php b/lib/private/Template/ResourceLocator.php
index f721906e12b..2127161f28c 100755
--- a/lib/private/Template/ResourceLocator.php
+++ b/lib/private/Template/ResourceLocator.php
@@ -107,6 +107,50 @@ abstract class ResourceLocator {
 	}
 
 	/**
+	 * Attempt to find the webRoot
+	 *
+	 * traverse the potential web roots upwards in the path
+	 *
+	 * example:
+	 *   - root: /srv/www/apps/myapp
+	 *   - available mappings: ['/srv/www']
+	 *
+	 * First we check if a mapping for /srv/www/apps/myapp is available,
+	 * then /srv/www/apps, /srv/www/apps, /srv/www, ... until we find a
+	 * valid web root
+	 *
+	 * @param string $root
+	 * @return string|null The web root or null on failure
+	 */
+	protected function findWebRoot($root) {
+		$webRoot = null;
+		$tmpRoot = $root;
+
+		while ($webRoot === null) {
+			if (isset($this->mapping[$tmpRoot])) {
+				$webRoot = $this->mapping[$tmpRoot];
+				break;
+			}
+
+			if ($tmpRoot === '/') {
+				break;
+			}
+
+			$tmpRoot = dirname($tmpRoot);
+		}
+
+		if (!$webRoot) {
+			$realpath = realpath($root);
+
+			if ($realpath && ($realpath !== $root)) {
+				return $this->findWebRoot($realpath);
+			}
+		}
+
+		return $webRoot;
+	}
+
+	/**
 	 * append the $file resource at $root
 	 *
 	 * @param string $root path to check
@@ -125,38 +169,18 @@ abstract class ResourceLocator {
 		}
 
 		if (!$webRoot) {
-			$tmpRoot = realpath($root);
-			/*
-			 * traverse the potential web roots upwards in the path
-			 *
-			 * example:
-			 *   - root: /srv/www/apps/myapp
-			 *   - available mappings: ['/srv/www']
-			 *
-			 * First we check if a mapping for /srv/www/apps/myapp is available,
-			 * then /srv/www/apps, /srv/www/apps, /srv/www, ... until we find a
-			 * valid web root
-			 */
-			do {
-				if (isset($this->mapping[$tmpRoot])) {
-					$webRoot = $this->mapping[$tmpRoot];
-					break;
-				}
-
-				if ($tmpRoot === '/') {
-					$webRoot = '';
-					$this->logger->error('ResourceLocator can not find a web root (root: {root}, file: {file}, webRoot: {webRoot}, throw: {throw})', [
-						'app' => 'lib',
-						'root' => $root,
-						'file' => $file,
-						'webRoot' => $webRoot,
-						'throw' => $throw ? 'true' : 'false'
-					]);
-					break;
-				}
-				$tmpRoot = dirname($tmpRoot);
-			} while(true);
-
+			$webRoot = $this->findWebRoot($root);
+
+			if (!$webRoot) {
+				$webRoot = '';
+				$this->logger->error('ResourceLocator can not find a web root (root: {root}, file: {file}, webRoot: {webRoot}, throw: {throw})', [
+					'app' => 'lib',
+					'root' => $root,
+					'file' => $file,
+					'webRoot' => $webRoot,
+					'throw' => $throw ? 'true' : 'false'
+				]);
+			}
 		}
 		$this->resources[] = array($root, $webRoot, $file);