Add ability to specify a callback for Curl::download()

src/Curl/Curl.php

@@ -150,12 +150,28 @@ class Curl
         return $this->exec();
     }
 
-    public function download($url, $filename)
+    public function download($url, $mixed_filename)
     {
-        $fh = fopen($filename, 'wb');
+        $callback = false;
+        if (is_callable($mixed_filename)) {
+            $callback = $mixed_filename;
+            $fh = tmpfile();
+        } else {
+            $filename = $mixed_filename;
+            $fh = fopen($filename, 'wb');
+        }
+
         $this->setOpt(CURLOPT_FILE, $fh);
         $this->get($url);
-        fclose($fh);
+
+        if ($callback) {
+            rewind($fh);
+            $callback($this, $fh);
+        }
+
+        if (is_resource($fh)) {
+            fclose($fh);
+        }
 
         // Fix "PHP Notice: Use of undefined constant STDOUT" when reading the
         // PHP script from stdin.

tests/PHPCurlClass/PHPCurlClassTest.php

@@ -468,6 +468,43 @@ class CurlTest extends PHPUnit_Framework_TestCase
         $this->assertFalse(file_exists($downloaded_file_path));
     }
 
+    public function testDownloadCallback()
+    {
+        // Upload a file.
+        $upload_file_path = Helper\get_png();
+        $upload_test = new Test();
+        $upload_test->server('upload_response', 'POST', array(
+            'image' => '@' . $upload_file_path,
+        ));
+        $uploaded_file_path = $upload_test->curl->response->file_path;
+
+        // Download the file.
+        $callback_called = false;
+        $curl = new Curl();
+        $curl->setHeader('X-DEBUG-TEST', 'download_response');
+        $curl->download(Test::TEST_URL . '?' . http_build_query(array(
+            'file_path' => $uploaded_file_path,
+        )), function($instance, $fh) use (&$callback_called) {
+            $callback_called = true;
+            PHPUnit_Framework_Assert::assertInstanceOf('Curl\Curl', $instance);
+            PHPUnit_Framework_Assert::assertTrue(is_resource($fh));
+            PHPUnit_Framework_Assert::assertEquals('stream', get_resource_type($fh));
+            PHPUnit_Framework_Assert::assertGreaterThan(0, strlen(stream_get_contents($fh)));
+            PHPUnit_Framework_Assert::assertEquals(0, strlen(stream_get_contents($fh)));
+            fclose($fh);
+        });
+        $this->assertTrue($callback_called);
+
+        // Remove server file.
+        $this->assertEquals('true', $upload_test->server('upload_cleanup', 'POST', array(
+            'file_path' => $uploaded_file_path,
+        )));
+
+        unlink($upload_file_path);
+        $this->assertFalse(file_exists($upload_file_path));
+        $this->assertFalse(file_exists($uploaded_file_path));
+    }
+
     public function testBasicHttpAuth()
     {
         $test = new Test();