64 lines
1.4 KiB
Go
64 lines
1.4 KiB
Go
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// +build linux
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package loopback
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import (
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"fmt"
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"os"
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"syscall"
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"github.com/Sirupsen/logrus"
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)
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func getLoopbackBackingFile(file *os.File) (uint64, uint64, error) {
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loopInfo, err := ioctlLoopGetStatus64(file.Fd())
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if err != nil {
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logrus.Errorf("Error get loopback backing file: %s", err)
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return 0, 0, ErrGetLoopbackBackingFile
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}
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return loopInfo.loDevice, loopInfo.loInode, nil
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}
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// SetCapacity reloads the size for the loopback device.
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func SetCapacity(file *os.File) error {
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if err := ioctlLoopSetCapacity(file.Fd(), 0); err != nil {
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logrus.Errorf("Error loopbackSetCapacity: %s", err)
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return ErrSetCapacity
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}
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return nil
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}
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// FindLoopDeviceFor returns a loopback device file for the specified file which
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// is backing file of a loop back device.
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func FindLoopDeviceFor(file *os.File) *os.File {
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stat, err := file.Stat()
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if err != nil {
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return nil
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}
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targetInode := stat.Sys().(*syscall.Stat_t).Ino
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targetDevice := stat.Sys().(*syscall.Stat_t).Dev
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for i := 0; true; i++ {
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path := fmt.Sprintf("/dev/loop%d", i)
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file, err := os.OpenFile(path, os.O_RDWR, 0)
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if err != nil {
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if os.IsNotExist(err) {
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return nil
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}
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// Ignore all errors until the first not-exist
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// we want to continue looking for the file
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continue
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}
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dev, inode, err := getLoopbackBackingFile(file)
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if err == nil && dev == targetDevice && inode == targetInode {
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return file
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}
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file.Close()
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}
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return nil
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}
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