using the number of writen bytes as indicator if streamCopy() was successfully. Instead check if fwrite returns the number of bytes or false

lib/files/view.php

@@ -361,10 +361,9 @@ class View {
 				} else {
 					$source = $this->fopen($path1 . $postFix1, 'r');
 					$target = $this->fopen($path2 . $postFix2, 'w');
-					$count = \OC_Helper::streamCopy($source, $target);
+					$result = \OC_Helper::streamCopy($source, $target);
 					list($storage1, $internalPath1) = Filesystem::resolvePath($absolutePath1 . $postFix1);
 					$storage1->unlink($internalPath1);
-					$result = $count > 0;
 				}
 				if ($this->fakeRoot == Filesystem::getRoot()) {
 					\OC_Hook::emit(

lib/helper.php

@@ -513,11 +513,13 @@ class OC_Helper {
 		if(!$source or !$target) {
 			return false;
 		}
-		$count=0;
+		$result=true;
 		while(!feof($source)) {
-			$count+=fwrite($target, fread($source, 8192));
+			if (fwrite($target, fread($source, 8192)) === false) {
+				$result = false;
+			}
 		}
-		return $count;
+		return $result;
 	}
 
 	/**