[ci skip] Update the index.php file

- Use DIRECTORY_SEPARATOR instead of a hard-coded forward-slash
- Use more proper terminology in comment descriptions
- Small tweaks to directory detection logic

2 files changed, 90 insertions, 52 deletions

diff --git a/index.php b/index.php
index 5cc37108a..6986e1e5d 100755
--- a/index.php
+++ b/index.php
@@ -91,24 +91,25 @@ switch (ENVIRONMENT)
 
 /*
  *---------------------------------------------------------------
- * SYSTEM FOLDER NAME
+ * SYSTEM DIRCTORY NAME
  *---------------------------------------------------------------
  *
- * This variable must contain the name of your "system" folder.
- * Include the path if the folder is not in the same directory
- * as this file.
+ * This variable must contain the name of your "system" directory.
+ * Set the path if it is not in the same directory as this file.
  */
 	$system_path = 'system';
 
 /*
  *---------------------------------------------------------------
- * APPLICATION FOLDER NAME
+ * APPLICATION DIRECTORY NAME
  *---------------------------------------------------------------
  *
  * If you want this front controller to use a different "application"
- * folder than the default one you can set its name here. The folder
- * can also be renamed or relocated anywhere on your server. If
- * you do, use a full server path. For more info please see the user guide:
+ * directory than the default one you can set its name here. The directory
+ * can also be renamed or relocated anywhere on your server. If you do,
+ * use an absolute (full) server path.
+ * For more info please see the user guide:
+ *
  * https://codeigniter.com/user_guide/general/managing_apps.html
  *
  * NO TRAILING SLASH!
@@ -117,14 +118,14 @@ switch (ENVIRONMENT)
 
 /*
  *---------------------------------------------------------------
- * VIEW FOLDER NAME
+ * VIEW DIRECTORY NAME
  *---------------------------------------------------------------
  *
- * If you want to move the view folder out of the application
- * folder set the path to the folder here. The folder can be renamed
+ * If you want to move the view directory out of the application
+ * directory, set the path to it here. The directory can be renamed
  * and relocated anywhere on your server. If blank, it will default
- * to the standard location inside your application folder. If you
- * do move this, use the full server path to this folder.
+ * to the standard location inside your application directory.
+ * If you do move this, use an absolute (full) server path.
  *
  * NO TRAILING SLASH!
  */
@@ -150,8 +151,8 @@ switch (ENVIRONMENT)
  *
  * Un-comment the $routing array below to use this feature
  */
-	// The directory name, relative to the "controllers" folder.  Leave blank
-	// if your controller is not in a sub-folder within the "controllers" folder
+	// The directory name, relative to the "controllers" directory.  Leave blank
+	// if your controller is not in a sub-directory within the "controllers" one
 	// $routing['directory'] = '';
 
 	// The controller class file name.  Example:  mycontroller
@@ -197,12 +198,16 @@ switch (ENVIRONMENT)
 
 	if (($_temp = realpath($system_path)) !== FALSE)
 	{
-		$system_path = $_temp.'/';
+		$system_path = $_temp.DIRECTORY_SEPARATOR;
 	}
 	else
 	{
 		// Ensure there's a trailing slash
-		$system_path = rtrim($system_path, '/').'/';
+		$system_path = strtr(
+			rtrim($system_path, '/\\'),
+			'/\\',
+			DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
+		).DIRECTORY_SEPARATOR;
 	}
 
 	// Is the system path correct?
@@ -221,66 +226,84 @@ switch (ENVIRONMENT)
 	// The name of THIS file
 	define('SELF', pathinfo(__FILE__, PATHINFO_BASENAME));
 
-	// Path to the system folder
-	define('BASEPATH', str_replace('\\', '/', $system_path));
+	// Path to the system directory
+	define('BASEPATH', $system_path);
 
-	// Path to the front controller (this file)
-	define('FCPATH', dirname(__FILE__).'/');
+	// Path to the front controller (this file) directory
+	define('FCPATH', dirname(__FILE__).DIRECTORY_SEPARATOR);
 
-	// Name of the "system folder"
-	define('SYSDIR', trim(strrchr(trim(BASEPATH, '/'), '/'), '/'));
+	// Name of the "system" directory
+	define('SYSDIR', basename(BASEPATH));
 
-	// The path to the "application" folder
+	// The path to the "application" directory
 	if (is_dir($application_folder))
 	{
 		if (($_temp = realpath($application_folder)) !== FALSE)
 		{
-			$application_folder = $_temp;
+			$application_folder = $_temp.DIRECTORY_SEPARATOR;
+		}
+		else
+		{
+			$application_folder = strtr(
+				rtrim($application_folder, '/\\'),
+				'/\\',
+				DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
+			);
 		}
-
-		define('APPPATH', $application_folder.DIRECTORY_SEPARATOR);
+	}
+	elseif (is_dir(BASEPATH.$application_folder.DIRECTORY_SEPARATOR))
+	{
+		$application_folder = BASEPATH.strtr(
+			trim($application_folder, '/\\'),
+			'/\\',
+			DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
+		);
 	}
 	else
 	{
-		if ( ! is_dir(BASEPATH.$application_folder.DIRECTORY_SEPARATOR))
-		{
-			header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
-			echo 'Your application folder path does not appear to be set correctly. Please open the following file and correct this: '.SELF;
-			exit(3); // EXIT_CONFIG
-		}
-
-		define('APPPATH', BASEPATH.$application_folder.DIRECTORY_SEPARATOR);
+		header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
+		echo 'Your application folder path does not appear to be set correctly. Please open the following file and correct this: '.SELF;
+		exit(3); // EXIT_CONFIG
 	}
 
-	// The path to the "views" folder
-	if ( ! is_dir($view_folder))
+	define('APPPATH', $application_folder.DIRECTORY_SEPARATOR);
+
+	// The path to the "views" directory
+	if ( ! isset($view_folder[0]) && is_dir(APPPATH.'views'.DIRECTORY_SEPARATOR))
 	{
-		if ( ! empty($view_folder) && is_dir(APPPATH.$view_folder.DIRECTORY_SEPARATOR))
-		{
-			$view_folder = APPPATH.$view_folder;
-		}
-		elseif ( ! is_dir(APPPATH.'views'.DIRECTORY_SEPARATOR))
+		$view_folder = APPPATH.'views';
+	}
+	elseif (is_dir($view_folder))
+	{
+		if (($_temp = realpath($view_folder)) !== FALSE)
 		{
-			header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
-			echo 'Your view folder path does not appear to be set correctly. Please open the following file and correct this: '.SELF;
-			exit(3); // EXIT_CONFIG
+			$view_folder = $_temp;
 		}
 		else
 		{
-			$view_folder = APPPATH.'views';
+			$view_folder = strtr(
+				rtrim($view_folder, '/\\'),
+				'/\\',
+				DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
+			);
 		}
 	}
-
-	if (($_temp = realpath($view_folder)) !== FALSE)
+	elseif (is_dir(APPPATH.$view_folder.DIRECTORY_SEPARATOR))
 	{
-		$view_folder = $_temp.DIRECTORY_SEPARATOR;
+		$view_folder = APPPATH.strtr(
+			trim($view_folder, '/\\'),
+			'/\\',
+			DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
+		);
 	}
 	else
 	{
-		$view_folder = rtrim($view_folder, '/\\').DIRECTORY_SEPARATOR;
+		header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
+		echo 'Your view folder path does not appear to be set correctly. Please open the following file and correct this: '.SELF;
+		exit(3); // EXIT_CONFIG
 	}
 
-	define('VIEWPATH', $view_folder);
+	define('VIEWPATH', $view_folder.DIRECTORY_SEPARATOR);
 
 /*
  * --------------------------------------------------------------------
diff --git a/user_guide_src/source/installation/upgrade_306.rst b/user_guide_src/source/installation/upgrade_306.rst
index f6d2f13d4..3863e0afa 100644
--- a/user_guide_src/source/installation/upgrade_306.rst
+++ b/user_guide_src/source/installation/upgrade_306.rst
@@ -13,7 +13,22 @@ Replace all files and directories in your *system/* directory.
 .. note:: If you have any custom developed files in these directories,
 	please make copies of them first.
 
-Step 2: Remove 'prep_for_form' usage (deprecation)
+Step 2: Update your index.php file (optional)
+=============================================
+
+We've made some tweaks to the index.php file, mostly related to proper
+usage of directory separators (i.e. use the ``DIRECTORY_SEPARATOR``
+constant instead of a hard coded forward slash "/").
+
+Nothing will break if you skip this step, but if you're running Windows
+or just want to be up to date with every change - we do recommend that
+you update your index.php file.
+
+*Tip: Just copy the ``ENVIRONMENT``, ``$system_path``, ``$application_folder``
+and ``$view_folder`` declarations from the old file and put them into the
+new one, replacing the defaults.*
+
+Step 3: Remove 'prep_for_form' usage (deprecation)
 ==================================================
 
 The :doc:`Form Validation Library <../libraries/form_validation>` has a