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// Copyright (c) Contributors to the Apptainer project, established as
// Apptainer a Series of LF Projects LLC.
// For website terms of use, trademark policy, privacy policy and other
// project policies see https://lfprojects.org/policies
// Copyright (c) 2020, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE.md file distributed with the sources of this project regarding your
// rights to use or distribute this software.
package image
import (
"fmt"
"github.com/apptainer/apptainer/pkg/runtime/engine/config"
)
// DriverFeature defines a feature type that a driver is supporting.
type DriverFeature uint16
const (
// SquashFeature means the driver handles squashfs image mounts.
SquashFeature DriverFeature = 1 << iota
// Ext3Feature means the driver handles ext3fs image mounts.
Ext3Feature
// GocryptFeature means the driver handles gocryptfs image mounts.
GocryptFeature
// OverlayFeature means the driver handle overlay mount.
OverlayFeature
// FuseFeature means the driver uses FUSE as its base.
FuseFeature
)
// ImageFeature means the driver handles any of the image mount types
const ImageFeature = SquashFeature | Ext3Feature | GocryptFeature
// MountFunc defines mount function prototype
type MountFunc func(source string, target string, filesystem string, flags uintptr, data string) error
// MountParams defines parameters passed to driver interface
// while mounting images.
type MountParams struct {
Source string // image source
Target string // image target mount point
Filesystem string // image filesystem type
Flags uintptr // mount flags
Offset uint64 // offset where start filesystem
Size uint64 // size of image filesystem
Key []byte // filesystem decryption key
FSOptions []string // filesystem mount options
DontElevatePrivs bool // omit cmd.SysProcAttr, currently only used by gocryptfs
}
// DriverParams defines parameters passed to driver interface
// while starting it.
type DriverParams struct {
SessionPath string // session driver image path
UsernsFd int // user namespace file descriptor
FuseFd int // fuse file descriptor
Config *config.Common // common engine configuration
}
// Driver defines the image driver interface to register.
type Driver interface {
// Mount is called each time an engine mount an image
Mount(*MountParams, MountFunc) error
// MountErr returns driver mount errors.
MountErr() error
// Start the driver for initialization.
Start(*DriverParams, int, bool) error
// Stop the driver related to given mount target for cleanup,
// an empty target signify to the driver to prepare for stop.
Stop(string) error
// Features Feature returns supported features.
Features() DriverFeature
}
// drivers holds all registered image drivers
var drivers = make(map[string]Driver)
// RegisterDriver registers an image driver by name.
func RegisterDriver(name string, driver Driver) error {
if name == "" {
return fmt.Errorf("empty name")
} else if _, ok := drivers[name]; ok {
return fmt.Errorf("%s is already registered", name)
} else if driver == nil {
return fmt.Errorf("nil driver")
}
drivers[name] = driver
return nil
}
// GetDriver returns the named image driver interface.
func GetDriver(name string) Driver {
return drivers[name]
}
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