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package system // import "github.com/docker/docker/pkg/system"
import (
"golang.org/x/sys/unix"
)
// Lgetxattr retrieves the value of the extended attribute identified by attr
// and associated with the given path in the file system.
// It will returns a nil slice and nil error if the xattr is not set.
func Lgetxattr(path string, attr string) ([]byte, error) {
sysErr := func(err error) ([]byte, error) {
return nil, &XattrError{Op: "lgetxattr", Attr: attr, Path: path, Err: err}
}
// Start with a 128 length byte array
dest := make([]byte, 128)
sz, errno := unix.Lgetxattr(path, attr, dest)
for errno == unix.ERANGE {
// Buffer too small, use zero-sized buffer to get the actual size
sz, errno = unix.Lgetxattr(path, attr, []byte{})
if errno != nil {
return sysErr(errno)
}
dest = make([]byte, sz)
sz, errno = unix.Lgetxattr(path, attr, dest)
}
switch {
case errno == unix.ENODATA:
return nil, nil
case errno != nil:
return sysErr(errno)
}
return dest[:sz], nil
}
// Lsetxattr sets the value of the extended attribute identified by attr
// and associated with the given path in the file system.
func Lsetxattr(path string, attr string, data []byte, flags int) error {
err := unix.Lsetxattr(path, attr, data, flags)
if err != nil {
return &XattrError{Op: "lsetxattr", Attr: attr, Path: path, Err: err}
}
return nil
}
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