Add duplicate handling and CHANGELOG.

Author: Zegnat

CHANGELOG.md

@@ -0,0 +1,18 @@
+# Change Log
+All notable changes to this project will be documented in this file.
+This project adheres to [Semantic Versioning](http://semver.org/).
+
+## [Unreleased]
+### Added
+- This CHANGELOG file.
+
+### Changed
+- Handle duplicate files in the same way as the Python implementation, adding
+  the new 409 response code from API v2.
+
+## 1.0.0-rc.1 - 2015-11-03
+### Added
+- The server implementation all packed in a single file.
+- Documentation to help people get started.
+
+[Unreleased]: https://github.com/PhotoBackup/server-php/compare/v1.0.0-rc.1...HEAD

index.php

@@ -127,6 +127,18 @@
 $filename = preg_replace('@[^0-9a-z._-]@i', '', $filename);
 $target = $MediaRoot . '/' . $filename;
 
+/**
+ * If a file with the same name and size exists, treat the new upload as a
+ * duplicate and exit.
+ */
+if (
+    file_exists($target) &&
+    filesize() === $_POST['filesize']
+) {
+    header($protocol . ' 409 Conflict');
+    exit();
+}
+
 /**
  * Move the uploaded file into the target directory. If anything did not work,
  * exit with HTTP code 500.