"Not exact 3 files existent in folder" - wrong assumptions about file system

[d--j]

Trying to execute the updater I get

$ php updater.phar 
Nextcloud Updater - version: v16.0.3-3-ga0c2b25 dirty

Current version is 18.0.9.

Update to Nextcloud 19.0.3 available. (channel: "stable")
Following file will be downloaded automatically: https://download.nextcloud.com/server/releases/nextcloud-19.0.3.zip
Open changelog ↗

Steps that will be executed:
[ ] Check for expected files
[ ] Check for write permissions
[ ] Create backup
[ ] Downloading
[ ] Verify integrity
[ ] Extracting
[ ] Enable maintenance mode
[ ] Replace entry points
[ ] Delete old files
[ ] Move new files in place
[ ] Done

Start update? [y/N] y

Info: Pressing Ctrl-C will finish the currently running step and then stops the updater.

[✔] Check for expected files
[✔] Check for write permissions
[✔] Create backup
[✔] Downloading
[✘] Verify integrity failed
Not exact 3 files existent in folder

Update failed. To resume or retry just execute the updater again.

The error is thrown here:

updater/lib/Updater.php

Lines 576 to 586 in cbf2b53

	private function getDownloadedFilePath() {
	$storageLocation = $this->getDataDirectoryLocation() . '/updater-'.$this->getConfigOption('instanceid') . '/downloads/';
	$this->silentLog('[info] storage location: ' . $storageLocation);
	$files = scandir($storageLocation);
	// ., .. and downloaded zip archive
	if(count($files) !== 3) {
	throw new \Exception('Not exact 3 files existent in folder');
	}
	return $storageLocation . '/' . $files[2];
	}

updater/index.php

Lines 693 to 703 in cbf2b53

	private function getDownloadedFilePath() {
	$storageLocation = $this->getDataDirectoryLocation() . '/updater-'.$this->getConfigOption('instanceid') . '/downloads/';
	$this->silentLog('[info] storage location: ' . $storageLocation);
	$files = scandir($storageLocation);
	// ., .. and downloaded zip archive
	if(count($files) !== 3) {
	throw new \Exception('Not exact 3 files existent in folder');
	}
	return $storageLocation . '/' . $files[2];
	}

This function assumes that a scandir always includes . and .. (and that they are the first and second entry in a scandir). This assumption is wrong. The data folder of this particular Nextcloud installation is on a FUSE filesystem (more exactly, it's S3QL). This filesystem does not return . and .. in a scandir call. Also . and .. could be on different positions in the array, so unconditionally accessing the third entry is wrong, too.

Something like this should handle these cases:

 private function getDownloadedFilePath() { 
 	$storageLocation = $this->getDataDirectoryLocation() . '/updater-'.$this->getConfigOption('instanceid') . '/downloads/'; 
 	$this->silentLog('[info] storage location: ' . $storageLocation); 
  
 	$files = array_filter(scandir($storageLocation), function($path){ return $path != "." && $path != ".."; });
 	if(count($files) !== 1) { 
 		throw new \Exception('Not exactly 1 entry exists in folder'); 
 	} 
 	return $storageLocation . '/' . $files[0]; 
 } 

[MorrisJobke]

Fix is in #306