- Avoid reaching browscap.org's rate limit

src/phpbrowscap/Browscap.php

@@ -811,27 +811,45 @@ protected function _getRemoteIniFile($url, $path)
             }
         }
 
-        // Get updated .ini file
-        $browscap = $this->_getRemoteData($url);
+        if ($url != $path) {
+            // Check if it's possible to write to the .ini file.
+            if (is_file($path)) {
+                if (!is_writable($path)) {
+                    throw new Exception("Could not write to '$path' (check the permissions of the current/old ini file).");
+                }
+            }
+            else {
+                // Test writability by creating a file only if one already doesn't exist, so we can safely delete it after the test.
+                $test_file = fopen($path, 'a');
+                if ($test_file) {
+                    fclose($test_file);
+                    unlink($path);
+                }
+                else {
+                    throw new Exception("Could not write to '$path' (check the permissions of the cache directory).");
+                }
+            }
 
+            // Get updated .ini file
+            $browscap = $this->_getRemoteData($url);
 
-        $browscap = explode("\n", $browscap);
 
-        $pattern = self::REGEX_DELIMITER
-                 . '('
-                 . self::VALUES_TO_QUOTE
-                 . ')="?([^"]*)"?$'
-                 . self::REGEX_DELIMITER;
+            $browscap = explode("\n", $browscap);
 
+            $pattern = self::REGEX_DELIMITER
+                . '('
+                . self::VALUES_TO_QUOTE
+                . ')="?([^"]*)"?$'
+                . self::REGEX_DELIMITER;
 
-        // Ok, lets read the file
-        $content = '';
-        foreach ($browscap as $subject) {
-            $subject = trim($subject);
-            $content .= preg_replace($pattern, '$1="$2"', $subject) . "\n";
-        }
 
-        if ($url != $path) {
+            // Ok, lets read the file
+            $content = '';
+            foreach ($browscap as $subject) {
+                $subject = trim($subject);
+                $content .= preg_replace($pattern, '$1="$2"', $subject) . "\n";
+            }
+
             if (!file_put_contents($path, $content)) {
                 throw new Exception("Could not write .ini content to $path");
             }