126 lines
3.1 KiB
Go
126 lines
3.1 KiB
Go
// +build linux darwin
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package sysx
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import (
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"bytes"
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"syscall"
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"golang.org/x/sys/unix"
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)
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// Listxattr calls syscall listxattr and reads all content
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// and returns a string array
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func Listxattr(path string) ([]string, error) {
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return listxattrAll(path, unix.Listxattr)
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}
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// Removexattr calls syscall removexattr
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func Removexattr(path string, attr string) (err error) {
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return unix.Removexattr(path, attr)
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}
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// Setxattr calls syscall setxattr
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func Setxattr(path string, attr string, data []byte, flags int) (err error) {
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return unix.Setxattr(path, attr, data, flags)
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}
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// Getxattr calls syscall getxattr
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func Getxattr(path, attr string) ([]byte, error) {
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return getxattrAll(path, attr, unix.Getxattr)
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}
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// LListxattr lists xattrs, not following symlinks
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func LListxattr(path string) ([]string, error) {
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return listxattrAll(path, unix.Llistxattr)
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}
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// LRemovexattr removes an xattr, not following symlinks
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func LRemovexattr(path string, attr string) (err error) {
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return unix.Lremovexattr(path, attr)
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}
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// LSetxattr sets an xattr, not following symlinks
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func LSetxattr(path string, attr string, data []byte, flags int) (err error) {
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return unix.Lsetxattr(path, attr, data, flags)
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}
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// LGetxattr gets an xattr, not following symlinks
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func LGetxattr(path, attr string) ([]byte, error) {
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return getxattrAll(path, attr, unix.Lgetxattr)
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}
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const defaultXattrBufferSize = 5
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type listxattrFunc func(path string, dest []byte) (int, error)
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func listxattrAll(path string, listFunc listxattrFunc) ([]string, error) {
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var p []byte // nil on first execution
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for {
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n, err := listFunc(path, p) // first call gets buffer size.
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if err != nil {
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return nil, err
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}
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if n > len(p) {
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p = make([]byte, n)
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continue
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}
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p = p[:n]
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ps := bytes.Split(bytes.TrimSuffix(p, []byte{0}), []byte{0})
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var entries []string
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for _, p := range ps {
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s := string(p)
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if s != "" {
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entries = append(entries, s)
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}
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}
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return entries, nil
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}
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}
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type getxattrFunc func(string, string, []byte) (int, error)
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func getxattrAll(path, attr string, getFunc getxattrFunc) ([]byte, error) {
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p := make([]byte, defaultXattrBufferSize)
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for {
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n, err := getFunc(path, attr, p)
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if err != nil {
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if errno, ok := err.(syscall.Errno); ok && errno == syscall.ERANGE {
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p = make([]byte, len(p)*2) // this can't be ideal.
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continue // try again!
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}
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return nil, err
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}
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// realloc to correct size and repeat
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if n > len(p) {
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p = make([]byte, n)
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continue
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}
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return p[:n], nil
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}
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}
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