51 lines
910 B
Go
51 lines
910 B
Go
|
package resource
|
||
|
|
|
||
|
|
import (
|
||
|
|
"io"
|
||
|
|
"os"
|
||
|
|
)
|
||
|
|
|
||
|
|
// An Instance represents the content at some location accessed through some
|
||
|
|
// Provider. It's the data at some URL.
|
||
|
|
type Instance interface {
|
||
|
|
Get() (io.ReadCloser, error)
|
||
|
|
Put(io.Reader) error
|
||
|
|
Stat() (os.FileInfo, error)
|
||
|
|
io.ReaderAt
|
||
|
|
WriteAt([]byte, int64) (int, error)
|
||
|
|
Delete() error
|
||
|
|
}
|
||
|
|
|
||
|
|
type DirInstance interface {
|
||
|
|
Readdirnames() ([]string, error)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Creates a io.ReadSeeker to an Instance.
|
||
|
|
func ReadSeeker(r Instance) io.ReadSeeker {
|
||
|
|
fi, err := r.Stat()
|
||
|
|
if err != nil {
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
return io.NewSectionReader(r, 0, fi.Size())
|
||
|
|
}
|
||
|
|
|
||
|
|
// Move instance content, deleting the source if it succeeds.
|
||
|
|
func Move(from, to Instance) (err error) {
|
||
|
|
rc, err := from.Get()
|
||
|
|
if err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
defer rc.Close()
|
||
|
|
err = to.Put(rc)
|
||
|
|
if err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
from.Delete()
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
func Exists(i Instance) bool {
|
||
|
|
_, err := i.Stat()
|
||
|
|
return err == nil
|
||
|
|
}
|