New context at each call and possibility to add more options and params to the context

src/Composer/Downloader/FileDownloader.php

@@ -78,15 +78,14 @@ abstract class FileDownloader implements DownloaderInterface
             }
         }
 
-        $ctx = StreamContextFactory::getContext();
+        $options = array();
-
         if ($this->io->hasAuthorization($package->getSourceUrl())) {
             $auth = $this->io->getAuthorization($package->getSourceUrl());
             $authStr = base64_encode($auth['username'] . ':' . $auth['password']);
-            stream_context_set_option($ctx, 'http', 'header', "Authorization: Basic $authStr\r\n");
+            $options['http']['header'] = "Authorization: Basic $authStr\r\n";
         }
 
-        stream_context_set_params($ctx, array("notification" => array($this, 'callbackGet')));
+        $ctx = StreamContextFactory::getContext($options, array('notification' => array($this, 'callbackGet')));
 
         $this->io->overwrite("    Downloading: <comment>connection...</comment>", false);
         @copy($url, $fileName, $ctx);

src/Composer/Json/JsonFile.php

@@ -60,8 +60,10 @@ class JsonFile
      */
     public function read()
     {
-        $ctx = StreamContextFactory::getContext();
+        $ctx = StreamContextFactory::getContext(array(
-        stream_context_set_option($ctx, 'http', 'header', 'User-Agent: Composer/'.Composer::VERSION."\r\n");
+            'http' => array(
+                'header' => 'User-Agent: Composer/'.Composer::VERSION."\r\n"
+        )));
 
         $json = file_get_contents($this->path, false, $ctx);
         if (!$json) {

src/Composer/Util/StreamContextFactory.php

@@ -1,4 +1,5 @@
 <?php
+
 /*
  * This file is part of Composer.
  *
@@ -18,23 +19,19 @@ namespace Composer\Util;
  */
 final class StreamContextFactory
 {
-    private static $context;
-
     /**
      * Creates a context supporting HTTP proxies
      *
+     * @param array $options Options to merge with the default
+     * @param array $params  Parameters to specify on the context
      * @return resource Default context
      * @throws \RuntimeException if https proxy required and OpenSSL uninstalled
      */
-    public static function getContext()
+    static public function getContext(array $options = array(), array $params = array())
     {
-        if (null !== self::$context) {
+        $options = array_merge(array('http' => array()), $options);
-            return self::$context;
-        }
 
         // Handle system proxy
-        $params = array('http' => array());
-
         if (isset($_SERVER['HTTP_PROXY']) || isset($_SERVER['http_proxy'])) {
             // Some systems seem to rely on a lowercased version instead...
             $proxy = isset($_SERVER['HTTP_PROXY']) ? $_SERVER['HTTP_PROXY'] : $_SERVER['http_proxy'];
@@ -46,12 +43,12 @@ final class StreamContextFactory
                 throw new \RuntimeException('You must enable the openssl extension to use a proxy over https');
             }
             
-            $params['http'] = array(
+            $options['http'] = array(
                 'proxy'           => $proxy,
                 'request_fulluri' => true,
             );
         }
         
-        return self::$context = stream_context_create($params);
+        return stream_context_create($options, $params);
     }
 }