DockerCLI/vendor/github.com/stevvooe/continuity/sysx/xattr.go

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package sysx
import (
"bytes"
"fmt"
"syscall"
)
const defaultXattrBufferSize = 5
var ErrNotSupported = fmt.Errorf("not supported")
type listxattrFunc func(path string, dest []byte) (int, error)
func listxattrAll(path string, listFunc listxattrFunc) ([]string, error) {
var p []byte // nil on first execution
for {
n, err := listFunc(path, p) // first call gets buffer size.
if err != nil {
return nil, err
}
if n > len(p) {
p = make([]byte, n)
continue
}
p = p[:n]
ps := bytes.Split(bytes.TrimSuffix(p, []byte{0}), []byte{0})
var entries []string
for _, p := range ps {
s := string(p)
if s != "" {
entries = append(entries, s)
}
}
return entries, nil
}
}
type getxattrFunc func(string, string, []byte) (int, error)
func getxattrAll(path, attr string, getFunc getxattrFunc) ([]byte, error) {
p := make([]byte, defaultXattrBufferSize)
for {
n, err := getFunc(path, attr, p)
if err != nil {
if errno, ok := err.(syscall.Errno); ok && errno == syscall.ERANGE {
p = make([]byte, len(p)*2) // this can't be ideal.
continue // try again!
}
return nil, err
}
// realloc to correct size and repeat
if n > len(p) {
p = make([]byte, n)
continue
}
return p[:n], nil
}
}