Added CURL progress function callback when downloading/uploading.

Author: racklin

README.md

@@ -97,3 +97,19 @@ Delete an empty bucket:
 S3::deleteBucket($bucketName)
 ```
 
+### Progress Function
+
+Add a progress function when S3 downloading / uploading 
+
+```php
+S3::setProgressFunction('progress');
+
+function progress($resource,$download_size, $downloaded, $upload_size, $uploaded)
+{
+    if($download_size > 0)
+         echo $downloaded / $download_size  * 100;
+    ob_flush();
+    flush();
+    sleep(1); // just to see effect
+}
+```

S3.php

@@ -190,6 +190,15 @@ class S3
 	 */
 	private static $__signingKeyResource = false;
 
+	/**
+	 * CURL progress function callback 
+	 *
+	 * @var function
+	 * @access public
+	 * @static 
+	 */
+	public static $progressFunction = null;
+
 
 	/**
 	* Constructor - if you're not using the class statically
@@ -355,6 +364,17 @@ public static function freeSigningKey()
 			openssl_free_key(self::$__signingKeyResource);
 	}
 
+	/**
+	* Set progress function
+	*
+	* @param function $func Progress function 
+	* @return void
+	*/
+	public static function setProgressFunction($func = null)
+	{
+		self::$progressFunction = $func;
+	}
+
 
 	/**
 	* Internal error handler
@@ -2237,6 +2257,12 @@ public function getResponse()
 			default: break;
 		}
 
+		// set curl progress function callback
+		if (S3::$progressFunction) {
+			curl_setopt($curl, CURLOPT_NOPROGRESS, false);
+			curl_setopt($curl, CURLOPT_PROGRESSFUNCTION, S3::$progressFunction);
+		}
+
 		// Execute, grab errors
 		if (curl_exec($curl))
 			$this->response->code = curl_getinfo($curl, CURLINFO_HTTP_CODE);