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<?php
/**
* @todo document (needs one-sentence top-level class description).
*/
class FileStore {
const DELETE_ORIGINAL = 1;
/**
* Fetch the FileStore object for a given storage group
*/
static function get( $group ) {
global $wgFileStore;
if( isset( $wgFileStore[$group] ) ) {
$info = $wgFileStore[$group];
return new FileStore( $group,
$info['directory'],
$info['url'],
intval( $info['hash'] ) );
} else {
return null;
}
}
private function __construct( $group, $directory, $path, $hash ) {
$this->mGroup = $group;
$this->mDirectory = $directory;
$this->mPath = $path;
$this->mHashLevel = $hash;
}
/**
* Acquire a lock; use when performing write operations on a store.
* This is attached to your master database connection, so if you
* suffer an uncaught error the lock will be released when the
* connection is closed.
* @see Database::lock()
*/
static function lock() {
$dbw = wfGetDB( DB_MASTER );
$lockname = $dbw->addQuotes( FileStore::lockName() );
return $dbw->lock( $lockname, __METHOD__ );
}
/**
* Release the global file store lock.
* @see Database::unlock()
*/
static function unlock() {
$dbw = wfGetDB( DB_MASTER );
$lockname = $dbw->addQuotes( FileStore::lockName() );
return $dbw->unlock( $lockname, __METHOD__ );
}
private static function lockName() {
return 'MediaWiki.' . wfWikiID() . '.FileStore';
}
/**
* Copy a file into the file store from elsewhere in the filesystem.
* Should be protected by FileStore::lock() to avoid race conditions.
*
* @param $key storage key string
* @param $flags
* DELETE_ORIGINAL - remove the source file on transaction commit.
*
* @throws FSException if copy can't be completed
* @return FSTransaction
*/
function insert( $key, $sourcePath, $flags=0 ) {
$destPath = $this->filePath( $key );
return $this->copyFile( $sourcePath, $destPath, $flags );
}
/**
* Copy a file from the file store to elsewhere in the filesystem.
* Should be protected by FileStore::lock() to avoid race conditions.
*
* @param $key storage key string
* @param $flags
* DELETE_ORIGINAL - remove the source file on transaction commit.
*
* @throws FSException if copy can't be completed
* @return FSTransaction on success
*/
function export( $key, $destPath, $flags=0 ) {
$sourcePath = $this->filePath( $key );
return $this->copyFile( $sourcePath, $destPath, $flags );
}
private function copyFile( $sourcePath, $destPath, $flags=0 ) {
if( !file_exists( $sourcePath ) ) {
// Abort! Abort!
throw new FSException( "missing source file '$sourcePath'" );
}
$transaction = new FSTransaction();
if( $flags & self::DELETE_ORIGINAL ) {
$transaction->addCommit( FSTransaction::DELETE_FILE, $sourcePath );
}
if( file_exists( $destPath ) ) {
// An identical file is already present; no need to copy.
} else {
if( !file_exists( dirname( $destPath ) ) ) {
wfSuppressWarnings();
$ok = wfMkdirParents( dirname( $destPath ) );
wfRestoreWarnings();
if( !$ok ) {
throw new FSException(
"failed to create directory for '$destPath'" );
}
}
wfSuppressWarnings();
$ok = copy( $sourcePath, $destPath );
wfRestoreWarnings();
if( $ok ) {
wfDebug( __METHOD__." copied '$sourcePath' to '$destPath'\n" );
$transaction->addRollback( FSTransaction::DELETE_FILE, $destPath );
} else {
throw new FSException(
__METHOD__." failed to copy '$sourcePath' to '$destPath'" );
}
}
return $transaction;
}
/**
* Delete a file from the file store.
* Caller's responsibility to make sure it's not being used by another row.
*
* File is not actually removed until transaction commit.
* Should be protected by FileStore::lock() to avoid race conditions.
*
* @param $key storage key string
* @throws FSException if file can't be deleted
* @return FSTransaction
*/
function delete( $key ) {
$destPath = $this->filePath( $key );
if( false === $destPath ) {
throw new FSException( "file store does not contain file '$key'" );
} else {
return FileStore::deleteFile( $destPath );
}
}
/**
* Delete a non-managed file on a transactional basis.
*
* File is not actually removed until transaction commit.
* Should be protected by FileStore::lock() to avoid race conditions.
*
* @param $path file to remove
* @throws FSException if file can't be deleted
* @return FSTransaction
*
* @todo Might be worth preliminary permissions check
*/
static function deleteFile( $path ) {
if( file_exists( $path ) ) {
$transaction = new FSTransaction();
$transaction->addCommit( FSTransaction::DELETE_FILE, $path );
return $transaction;
} else {
throw new FSException( "cannot delete missing file '$path'" );
}
}
/**
* Stream a contained file directly to HTTP output.
* Will throw a 404 if file is missing; 400 if invalid key.
* @return true on success, false on failure
*/
function stream( $key ) {
$path = $this->filePath( $key );
if( $path === false ) {
wfHttpError( 400, "Bad request", "Invalid or badly-formed filename." );
return false;
}
if( file_exists( $path ) ) {
// Set the filename for more convenient save behavior from browsers
// FIXME: Is this safe?
header( 'Content-Disposition: inline; filename="' . $key . '"' );
require_once 'StreamFile.php';
wfStreamFile( $path );
} else {
return wfHttpError( 404, "Not found",
"The requested resource does not exist." );
}
}
/**
* Confirm that the given file key is valid.
* Note that a valid key may refer to a file that does not exist.
*
* Key should consist of a 31-digit base-36 SHA-1 hash and
* an optional alphanumeric extension, all lowercase.
* The whole must not exceed 64 characters.
*
* @param $key
* @return boolean
*/
static function validKey( $key ) {
return preg_match( '/^[0-9a-z]{31,32}(\.[0-9a-z]{1,31})?$/', $key );
}
/**
* Calculate file storage key from a file on disk.
* You must pass an extension to it, as some files may be calculated
* out of a temporary file etc.
*
* @param $path to file
* @param $extension
* @return string or false if could not open file or bad extension
*/
static function calculateKey( $path, $extension ) {
wfSuppressWarnings();
$hash = sha1_file( $path );
wfRestoreWarnings();
if( $hash === false ) {
wfDebug( __METHOD__.": couldn't hash file '$path'\n" );
return false;
}
$base36 = wfBaseConvert( $hash, 16, 36, 31 );
if( $extension == '' ) {
$key = $base36;
} else {
$key = $base36 . '.' . $extension;
}
// Sanity check
if( self::validKey( $key ) ) {
return $key;
} else {
wfDebug( __METHOD__.": generated bad key '$key'\n" );
return false;
}
}
/**
* Return filesystem path to the given file.
* Note that the file may or may not exist.
* @return string or false if an invalid key
*/
function filePath( $key ) {
if( self::validKey( $key ) ) {
return $this->mDirectory . DIRECTORY_SEPARATOR .
$this->hashPath( $key, DIRECTORY_SEPARATOR );
} else {
return false;
}
}
/**
* Return URL path to the given file, if the store is public.
* @return string or false if not public
*/
function urlPath( $key ) {
if( $this->mUrl && self::validKey( $key ) ) {
return $this->mUrl . '/' . $this->hashPath( $key, '/' );
} else {
return false;
}
}
private function hashPath( $key, $separator ) {
$parts = array();
for( $i = 0; $i < $this->mHashLevel; $i++ ) {
$parts[] = $key{$i};
}
$parts[] = $key;
return implode( $separator, $parts );
}
}
/**
* Wrapper for file store transaction stuff.
*
* FileStore methods may return one of these for undoable operations;
* you can then call its rollback() or commit() methods to perform
* final cleanup if dependent database work fails or succeeds.
*/
class FSTransaction {
const DELETE_FILE = 1;
/**
* Combine more items into a fancier transaction
*/
function add( FSTransaction $transaction ) {
$this->mOnCommit = array_merge(
$this->mOnCommit, $transaction->mOnCommit );
$this->mOnRollback = array_merge(
$this->mOnRollback, $transaction->mOnRollback );
}
/**
* Perform final actions for success.
* @return true if actions applied ok, false if errors
*/
function commit() {
return $this->apply( $this->mOnCommit );
}
/**
* Perform final actions for failure.
* @return true if actions applied ok, false if errors
*/
function rollback() {
return $this->apply( $this->mOnRollback );
}
// --- Private and friend functions below...
function __construct() {
$this->mOnCommit = array();
$this->mOnRollback = array();
}
function addCommit( $action, $path ) {
$this->mOnCommit[] = array( $action, $path );
}
function addRollback( $action, $path ) {
$this->mOnRollback[] = array( $action, $path );
}
private function apply( $actions ) {
$result = true;
foreach( $actions as $item ) {
list( $action, $path ) = $item;
if( $action == self::DELETE_FILE ) {
wfSuppressWarnings();
$ok = unlink( $path );
wfRestoreWarnings();
if( $ok )
wfDebug( __METHOD__.": deleting file '$path'\n" );
else
wfDebug( __METHOD__.": failed to delete file '$path'\n" );
$result = $result && $ok;
}
}
return $result;
}
}
/**
* @ingroup Exception
*/
class FSException extends MWException { }