moby/pkg/loopback/loopback.go
Sebastiaan van Stijn cff4f20c44
migrate to github.com/containerd/log v0.1.0
The github.com/containerd/containerd/log package was moved to a separate
module, which will also be used by upcoming (patch) releases of containerd.

This patch moves our own uses of the package to use the new module.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2023-10-11 17:52:23 +02:00

73 lines
1.9 KiB
Go

//go:build linux && cgo
// Package loopback provides utilities to work with loopback devices.
//
// Deprecated: this package is deprecated and will be removed in the next release.
package loopback // import "github.com/docker/docker/pkg/loopback"
import (
"context"
"fmt"
"os"
"github.com/containerd/log"
"golang.org/x/sys/unix"
)
func getLoopbackBackingFile(file *os.File) (uint64, uint64, error) {
loopInfo, err := unix.IoctlLoopGetStatus64(int(file.Fd()))
if err != nil {
log.G(context.TODO()).Errorf("Error get loopback backing file: %s", err)
return 0, 0, ErrGetLoopbackBackingFile
}
return loopInfo.Device, loopInfo.Inode, nil
}
// SetCapacity reloads the size for the loopback device.
//
// Deprecated: the loopback package is deprected and will be removed in the next release.
func SetCapacity(file *os.File) error {
if err := unix.IoctlSetInt(int(file.Fd()), unix.LOOP_SET_CAPACITY, 0); err != nil {
log.G(context.TODO()).Errorf("Error loopbackSetCapacity: %s", err)
return ErrSetCapacity
}
return nil
}
// FindLoopDeviceFor returns a loopback device file for the specified file which
// is backing file of a loop back device.
//
// Deprecated: the loopback package is deprected and will be removed in the next release.
func FindLoopDeviceFor(file *os.File) *os.File {
var stat unix.Stat_t
err := unix.Stat(file.Name(), &stat)
if err != nil {
return nil
}
targetInode := stat.Ino
targetDevice := uint64(stat.Dev) //nolint: unconvert // the type is 32bit on mips
for i := 0; true; i++ {
path := fmt.Sprintf("/dev/loop%d", i)
file, err := os.OpenFile(path, os.O_RDWR, 0)
if err != nil {
if os.IsNotExist(err) {
return nil
}
// Ignore all errors until the first not-exist
// we want to continue looking for the file
continue
}
dev, inode, err := getLoopbackBackingFile(file)
if err == nil && dev == targetDevice && inode == targetInode {
return file
}
file.Close()
}
return nil
}