distribution/registry/storage/walk.go
Stephen J Day 5d576bc0cd storage: enforce sorted traversal during Walk
Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-12-01 16:25:30 -08:00

59 lines
1.7 KiB
Go

package storage
import (
"errors"
"fmt"
"sort"
"github.com/docker/distribution/context"
storageDriver "github.com/docker/distribution/registry/storage/driver"
)
// ErrSkipDir is used as a return value from onFileFunc to indicate that
// the directory named in the call is to be skipped. It is not returned
// as an error by any function.
var ErrSkipDir = errors.New("skip this directory")
// WalkFn is called once per file by Walk
// If the returned error is ErrSkipDir and fileInfo refers
// to a directory, the directory will not be entered and Walk
// will continue the traversal. Otherwise Walk will return
type WalkFn func(fileInfo storageDriver.FileInfo) error
// Walk traverses a filesystem defined within driver, starting
// from the given path, calling f on each file
func Walk(ctx context.Context, driver storageDriver.StorageDriver, from string, f WalkFn) error {
children, err := driver.List(ctx, from)
if err != nil {
return err
}
sort.Stable(sort.StringSlice(children))
for _, child := range children {
// TODO(stevvooe): Calling driver.Stat for every entry is quite
// expensive when running against backends with a slow Stat
// implementation, such as s3. This is very likely a serious
// performance bottleneck.
fileInfo, err := driver.Stat(ctx, child)
if err != nil {
return err
}
err = f(fileInfo)
skipDir := (err == ErrSkipDir)
if err != nil && !skipDir {
return err
}
if fileInfo.IsDir() && !skipDir {
if err := Walk(ctx, driver, child, f); err != nil {
return err
}
}
}
return nil
}
// pushError formats an error type given a path and an error
// and pushes it to a slice of errors
func pushError(errors []error, path string, err error) []error {
return append(errors, fmt.Errorf("%s: %s", path, err))
}