vendor/github.com/fsouza/go-dockerclient/external/github.com/docker/docker/pkg/system/xattrs_linux.go

   1 package system
   2
   3 import (
   4         "syscall"
   5         "unsafe"
   6 )
   7
   8 // Lgetxattr retrieves the value of the extended attribute identified by attr
   9 // and associated with the given path in the file system.
  10 // It will returns a nil slice and nil error if the xattr is not set.
  11 func Lgetxattr(path string, attr string) ([]byte, error) {
  12         pathBytes, err := syscall.BytePtrFromString(path)
  13         if err != nil {
  14                 return nil, err
  15         }
  16         attrBytes, err := syscall.BytePtrFromString(attr)
  17         if err != nil {
  18                 return nil, err
  19         }
  20
  21         dest := make([]byte, 128)
  22         destBytes := unsafe.Pointer(&dest[0])
  23         sz, _, errno := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
  24         if errno == syscall.ENODATA {
  25                 return nil, nil
  26         }
  27         if errno == syscall.ERANGE {
  28                 dest = make([]byte, sz)
  29                 destBytes := unsafe.Pointer(&dest[0])
  30                 sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
  31         }
  32         if errno != 0 {
  33                 return nil, errno
  34         }
  35
  36         return dest[:sz], nil
  37 }
  38
  39 var _zero uintptr
  40
  41 // Lsetxattr sets the value of the extended attribute identified by attr
  42 // and associated with the given path in the file system.
  43 func Lsetxattr(path string, attr string, data []byte, flags int) error {
  44         pathBytes, err := syscall.BytePtrFromString(path)
  45         if err != nil {
  46                 return err
  47         }
  48         attrBytes, err := syscall.BytePtrFromString(attr)
  49         if err != nil {
  50                 return err
  51         }
  52         var dataBytes unsafe.Pointer
  53         if len(data) > 0 {
  54                 dataBytes = unsafe.Pointer(&data[0])
  55         } else {
  56                 dataBytes = unsafe.Pointer(&_zero)
  57         }
  58         _, _, errno := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(dataBytes), uintptr(len(data)), uintptr(flags), 0)
  59         if errno != 0 {
  60                 return errno
  61         }
  62         return nil
  63 }