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File Mode / Permissions Interface #49
Description
Currently we do not work around different permission systems.
How about to introduce an interface and some classes to handle this problem.
interface FileMode // or FilePermissions
{
const TYPE = 'unknown';
/**
* Check if file modes are supported by the fs.
*
* @return bool
*/
public function isSupported();
/**
* Test if file is readable for the current user.
* Which "user" is referenced, depends on the implementation
* and have to be automatically detected.
*
* @return bool
*/
public function isReadable();
/**
* Test if file is writeable for the current user.
* Which "user" is referenced, depends on the implementation
* and have to be automatically detected.
*
* @return bool
*/
public function isWriteable();
/**
* Test if file is executeable for the current user.
* Which "user" is referenced, depends on the implementation
* and have to be automatically detected.
*
* @return bool
*/
public function isExecuteable();
/**
* For stacked file permission systems, get the next hop.
*
* @return FileMode
*/
public function nextFileMode();
}Then we have multiple classes with specific methods.
The UnsupportedFileMode class that indicate that file permissions are not supported.
class UnsupportedFileMode implements FileMode
{
const TYPE = 'unsupported';
public function isSupported()
{
return false;
}
}The PrimitiveFileMode only know read, write, executeable. It does not know owner, groups or complex acl rules.
class PrimitiveFileMode implements FileMode
{
const TYPE = 'primitive';
public function isSupported()
{
return true;
}
public function isReadable();
public function isWriteable();
public function isExecuteable();
}The UnixFileMode only know read, write, executeable for owner, groups and others.
class UnixFileMode implements FileMode
{
const TYPE = 'unix';
public function isSupported()
{
return true;
}
public function isOwnerReadable();
public function isOwnerWriteable();
public function isOwnerExecuteable();
public function isGroupReadable();
public function isGroupWriteable();
public function isGroupExecuteable();
public function isOthersReadable();
public function isOthersWriteable();
public function isOthersExecuteable();
public function isSticky();
// maybe more
}As you expected, the ACLFileMode will allow access to acl rules.
An interface system like this allow us to respect the different permission system.
The FileMode::isSupported is mandatory, because in mounted or merged filesystem I don't have access to the underlaying filesystem to check the "file permissions" ability. The UnsupportedFileMode prevents File::getMode from returning null.
Also other systems are allowed to implement there own permission system. For example Contao could implement it's own ContaoPermissionsFileMode for example.
class ContaoPermissionsFileMode implements FileMode
{
const TYPE = 'contao';
public function isSupported()
{
return true;
}
public function isUserReadable($backendUserId);
public function isUserWriteable($backendUserId);
public function isMemberReadable($memberId);
public function isMemberWriteable($memberId);
}To allow access to different permission systems, for example the ContaoPermissionsFileMode is just an overlay over UnixFileMode, the File::getMode should be extended with a type parameter:
interface File
{
/**
* Get permission access object for this file.
*
* @param string $type The permission system to access.
* If null the filesystem default permission system will be returned.
*
* @throw UnsupportedPermissionSystemException will be thrown if the requested permission system is not available.
*/
public function getMode($type = null);
}To access different permission systems just use the TYPE constant:
/** @var ContaoFilesystem $fs */
$file = $fs->getFile('foo');
/** @var ContaoPermissionsFileMode $contaoPerms */
$contaoPerms = $file->getMode();
// forcing a permission system (not good)
try {
/** @var UnixFileMode $unixPerms */
$unixPerms = $file->getMode(UnixFileMode::TYPE);
} catch (UnsupportedPermissionSystemException $e) {
// unix unsupported, maybe it is a linked in remote share like dropbox or amazon S3
}
// get the next permission system (good way)
/** @var UnixFileMode|DropboxFileMode|AmazonS3FileMode|... $nextPerms */
$nextPerms = $contaoPerms->nextFileMode();This allow us to transparent add file permission systems, nobody knows about it, but it will protect the files. The File::isReadable, File::isWriteable and File::isExecuteable should be shortcuts to the FileMode::isReadable, FileMode::isWriteable, FileMode::isExecuteable methods.
Activity
tristanlins commentedon May 27, 2013
The method
will be dropped. The adapter have to check its own native permissions and then check permission - if available - against an extended permission manager.