Adds the ability to export an album using streaming tar.

controllers/Download.php

@@ -0,0 +1,122 @@
+<?php
+/*****************************************************************************
+ * Download.php
+ * Contains the code to download an album.
+ *
+ * Kabuki CMS (C) 2013-2019, Aaron van Geffen
+ *****************************************************************************/
+
+class Download extends HTMLController
+{
+	public function __construct()
+	{
+		// Ensure we're logged in at this point.
+		$user = Registry::get('user');
+		if (!$user->isLoggedIn())
+			throw new NotAllowedException();
+
+		if(!isset($_GET['tag']))
+			throw new UnexpectedValueException('Must specify an album to download');
+
+		$tag = (int)$_GET['tag'];
+		$album = Tag::fromId($tag);
+
+		if($album->kind !== 'Album')
+			throw new UnexpectedValueException('Specified tag does not correspond to an album');
+
+		//Yes TOCTOU but it does not need to be perfect.
+		$lock_file = join('/', array(sys_get_temp_dir(), 'pics-export.lock'));
+		if(!file_exists($lock_file))
+		{
+			try
+			{
+				$fp = fopen($lock_file, 'x');
+
+				if(!$fp)
+					throw new UnexpectedValueException('Could not open lock-file');
+					
+				$this->exportAlbum($album);
+			}
+			finally
+			{
+  			fclose($fp);
+				unlink($lock_file);
+			}
+		}
+		else
+			throw new UnexpectedValueException('Another export is busy, please try again later');
+
+		exit();
+	}
+
+	private function exportAlbum($album)
+	{
+		$files = array();
+
+		$album_ids = array_merge(array($album->id_tag), $this->getChildAlbumIds($album->id_tag));
+		foreach($album_ids as $album_id)
+		{
+			$iterator = AssetIterator::getByOptions(
+				array(
+					'id_tag' => $album_id
+				)
+			);
+			while($asset = $iterator->Next())
+			{
+				$files[] = join(DIRECTORY_SEPARATOR, array('.', $asset->getSubdir(), $asset->getFilename()));
+			}
+		}
+
+		$descriptorspec = array(
+			0 => array('pipe', 'r'),
+			1 => array('pipe', 'w'),
+		);
+
+		$command = 'tar --null -cf - -T -';
+
+		$proc = proc_open($command, $descriptorspec, $pipes, ASSETSDIR);
+
+		if(!$proc)
+			throw new UnexpectedValueException('Could not execute TAR command');
+
+		if(!$pipes[0])
+			throw new UnexpectedValueException('Could not open pipe for STDIN');
+
+		if(!$pipes[1])
+			throw new UnexpectedValueException('Could not open pipe for STDOUT');
+
+		$album_name = $album->tag;
+
+		header('Pragma: no-cache');
+		header('Content-Description: File Download');
+		header('Content-disposition: attachment; filename="' . $album_name . '.tar"');
+		header('Content-Type: application/octet-stream');
+		header('Content-Transfer-Encoding: binary');
+
+		foreach($files as $file)
+			fwrite($pipes[0], $file . "\0");
+
+		fclose($pipes[0]);
+
+		while($chunk = stream_get_contents($pipes[1], 4096))
+			echo $chunk;
+
+		fclose($pipes[1]);
+
+		proc_close($proc);
+	}
+
+	private function getChildAlbumIds($parent_id)
+	{
+		$ids = array();
+
+		$albums = Tag::getAlbums($parent_id, 0, PHP_INT_MAX, 'object');
+		foreach($albums as $album)
+		{
+			$ids[] = $album->id_tag;
+			$ids = array_merge($ids, $this->getChildAlbumIds($album->id_tag));
+		}
+
+		return $ids;
+	}
+}

controllers/ViewPhotoAlbum.php

@@ -61,7 +61,13 @@ class ViewPhotoAlbum extends HTMLController
 		// Can we do fancy things here?
 		// !!! TODO: permission system?
 		$buttons = [];
+
 		if (Registry::get('user')->isLoggedIn())
+			$buttons[] = [
+				'url' => BASEURL . '/download/?tag=' . $id_tag,
+				'caption' => 'Download this album',
+			];
+
 			$buttons[] = [
 				'url' => BASEURL . '/uploadmedia/?tag=' . $id_tag,
 				'caption' => 'Upload new photos here',

models/Dispatcher.php

@@ -28,6 +28,7 @@ class Dispatcher
 			'suggest' => 'ProvideAutoSuggest',
 			'timeline' => 'ViewTimeline',
 			'uploadmedia' => 'UploadMedia',
+			'download' => 'Download',
 		];
 
 		// Work around PHP's FPM not always providing PATH_INFO.