DockerCLI/vendor/github.com/opencontainers/runc/libcontainer/system/xattrs_linux.go

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package system
import "golang.org/x/sys/unix"
// Returns a []byte slice if the xattr is set and nil otherwise
// Requires path and its attribute as arguments
func Lgetxattr(path string, attr string) ([]byte, error) {
var sz int
// Start with a 128 length byte array
dest := make([]byte, 128)
sz, errno := unix.Lgetxattr(path, attr, dest)
switch {
case errno == unix.ENODATA:
return nil, errno
case errno == unix.ENOTSUP:
return nil, errno
case errno == unix.ERANGE:
// 128 byte array might just not be good enough,
// A dummy buffer is used to get the real size
// of the xattrs on disk
sz, errno = unix.Lgetxattr(path, attr, []byte{})
if errno != nil {
return nil, errno
}
dest = make([]byte, sz)
sz, errno = unix.Lgetxattr(path, attr, dest)
if errno != nil {
return nil, errno
}
case errno != nil:
return nil, errno
}
return dest[:sz], nil
}