github.com/stackdocker/rkt@v0.10.1-0.20151109095037-1aa827478248/pkg/fileutil/xattrs_linux.go (about) 1 // Copyright 2014 Red Hat, Inc 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 // +build linux 16 17 // These functions are from github.com/docker/docker/pkg/system 18 19 package fileutil 20 21 import ( 22 "syscall" 23 "unsafe" 24 ) 25 26 // Returns a nil slice and nil error if the xattr is not set 27 func Lgetxattr(path string, attr string) ([]byte, error) { 28 pathBytes, err := syscall.BytePtrFromString(path) 29 if err != nil { 30 return nil, err 31 } 32 attrBytes, err := syscall.BytePtrFromString(attr) 33 if err != nil { 34 return nil, err 35 } 36 37 dest := make([]byte, 128) 38 destBytes := unsafe.Pointer(&dest[0]) 39 sz, _, errno := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0) 40 if errno == syscall.ENODATA { 41 return nil, nil 42 } 43 if errno == syscall.ERANGE { 44 dest = make([]byte, sz) 45 destBytes := unsafe.Pointer(&dest[0]) 46 sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0) 47 } 48 if errno != 0 { 49 return nil, errno 50 } 51 52 return dest[:sz], nil 53 } 54 55 var _zero uintptr 56 57 func Lsetxattr(path string, attr string, data []byte, flags int) error { 58 pathBytes, err := syscall.BytePtrFromString(path) 59 if err != nil { 60 return err 61 } 62 attrBytes, err := syscall.BytePtrFromString(attr) 63 if err != nil { 64 return err 65 } 66 var dataBytes unsafe.Pointer 67 if len(data) > 0 { 68 dataBytes = unsafe.Pointer(&data[0]) 69 } else { 70 dataBytes = unsafe.Pointer(&_zero) 71 } 72 _, _, errno := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(dataBytes), uintptr(len(data)), uintptr(flags), 0) 73 if errno != 0 { 74 return errno 75 } 76 return nil 77 }