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moby--moby/pkg/system/rm.go

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package system
import (
"os"
"syscall"
"time"
"github.com/docker/docker/pkg/mount"
"github.com/pkg/errors"
)
// EnsureRemoveAll wraps `os.RemoveAll` to check for specific errors that can
// often be remedied.
// Only use `EnsureRemoveAll` if you really want to make every effort to remove
// a directory.
//
// Because of the way `os.Remove` (and by extension `os.RemoveAll`) works, there
// can be a race between reading directory entries and then actually attempting
// to remove everything in the directory.
// These types of errors do not need to be returned since it's ok for the dir to
// be gone we can just retry the remove operation.
//
// This should not return a `os.ErrNotExist` kind of error under any cirucmstances
func EnsureRemoveAll(dir string) error {
notExistErr := make(map[string]bool)
// track retries
exitOnErr := make(map[string]int)
maxRetry := 5
// Attempt to unmount anything beneath this dir first
mount.RecursiveUnmount(dir)
for {
err := os.RemoveAll(dir)
if err == nil {
return err
}
pe, ok := err.(*os.PathError)
if !ok {
return err
}
if os.IsNotExist(err) {
if notExistErr[pe.Path] {
return err
}
notExistErr[pe.Path] = true
// There is a race where some subdir can be removed but after the parent
// dir entries have been read.
// So the path could be from `os.Remove(subdir)`
// If the reported non-existent path is not the passed in `dir` we
// should just retry, but otherwise return with no error.
if pe.Path == dir {
return nil
}
continue
}
if pe.Err != syscall.EBUSY {
return err
}
if mounted, _ := mount.Mounted(pe.Path); mounted {
if e := mount.Unmount(pe.Path); e != nil {
if mounted, _ := mount.Mounted(pe.Path); mounted {
return errors.Wrapf(e, "error while removing %s", dir)
}
}
}
if exitOnErr[pe.Path] == maxRetry {
return err
}
exitOnErr[pe.Path]++
time.Sleep(100 * time.Millisecond)
}
}