Index: install.php
===================================================================
RCS file: /cvs/drupal/drupal/install.php,v
retrieving revision 1.30
diff -u -p -r1.30 install.php
--- install.php	17 Dec 2006 06:51:47 -0000	1.30
+++ install.php	21 Dec 2006 06:11:41 -0000
@@ -17,6 +17,10 @@ require_once './includes/install.inc';
 function install_main() {
   global $profile, $install_locale;
   require_once './includes/bootstrap.inc';
+  $settings_file = './'. conf_path() .'/settings.php';
+  // If the settings file exists but is unreadable, try to change the
+  // permissions so that it is readable (i.e. the web server is the owner).
+  drupal_verify_install_file($settings_file, FILE_EXIST|FILE_READABLE);
   drupal_bootstrap(DRUPAL_BOOTSTRAP_CONFIGURATION);
   require_once './modules/system/system.install';
 
@@ -83,7 +87,6 @@ function install_main() {
   drupal_install_profile($profile, $modules);
 
   // Warn about settings.php permissions risk
-  $settings_file = './'. conf_path() .'/settings.php';
   if (!drupal_verify_install_file($settings_file, FILE_EXIST|FILE_READABLE|FILE_NOT_WRITABLE)) {
     drupal_set_message(st('All necessary changes to %file have been made, so you should now remove write permissions to this file. Failure to remove write permissions to this file is a security risk.', array('%file' => $settings_file)), 'error');
   }
@@ -107,7 +110,8 @@ function install_verify_settings() {
   global $db_prefix, $db_type, $db_url;
 
   // Verify existing settings (if any).
-  if ($_SERVER['REQUEST_METHOD'] == 'GET' && $db_url != 'mysql://username:password@localhost/databasename') {
+  // If settings.php does not exist or is unreadable db_url won't be set.
+  if ($_SERVER['REQUEST_METHOD'] == 'GET' && isset($db_url) && $db_url != 'mysql://username:password@localhost/databasename') {
     // We need this because we want to run form_get_errors.
     include_once './includes/form.inc';
 
Index: includes/bootstrap.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/bootstrap.inc,v
retrieving revision 1.142
diff -u -p -r1.142 bootstrap.inc
--- includes/bootstrap.inc	12 Dec 2006 06:27:17 -0000	1.142
+++ includes/bootstrap.inc	21 Dec 2006 06:11:41 -0000
@@ -235,7 +235,7 @@ function drupal_unset_globals() {
 function conf_init() {
   global $db_url, $db_prefix, $base_url, $base_path, $base_root, $conf, $installed_profile;
   $conf = array();
-  include_once './'. conf_path() .'/settings.php';
+  @include_once './'. conf_path() . '/settings.php';
 
   if (isset($base_url)) {
     // Parse fixed base URL from settings.php.
Index: includes/install.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/install.inc,v
retrieving revision 1.30
diff -u -p -r1.30 install.inc
--- includes/install.inc	8 Dec 2006 11:54:04 -0000	1.30
+++ includes/install.inc	21 Dec 2006 06:11:41 -0000
@@ -391,20 +391,21 @@ function drupal_verify_install_file($fil
 
   // Verify file permissions.
   if (isset($mask)) {
-    $masks = array(FILE_EXIST, FILE_READABLE, FILE_WRITABLE, FILE_EXECUTABLE, FILE_NOT_READABLE, FILE_NOT_WRITABLE, FILE_NOT_EXECUTABLE);
+    // File must exist for any of the other checks to make sense.
+    if ($mask & FILE_EXIST) {
+      if (!file_exists($file)) {
+        if ($type == 'dir') {
+          drupal_install_mkdir($file, $mask);
+        }
+        if (!file_exists($file)) {
+          return FALSE;
+        }
+      }
+    }
+    $masks = array(FILE_READABLE, FILE_WRITABLE, FILE_EXECUTABLE, FILE_NOT_READABLE, FILE_NOT_WRITABLE, FILE_NOT_EXECUTABLE);
     foreach ($masks as $current_mask) {
       if ($mask & $current_mask) {
         switch ($current_mask) {
-          case FILE_EXIST:
-            if (!file_exists($file)) {
-              if ($type == 'dir') {
-                drupal_install_mkdir($file, $mask);
-              }
-              if (!file_exists($file)) {
-                $return = FALSE;
-              }
-            }
-            break;
           case FILE_READABLE:
             if (!is_readable($file) && !drupal_install_fix_file($file, $mask)) {
               $return = FALSE;