func setupDumpStackTrap(root string) {
// Windows does not support signals like *nix systems. So instead of
// trapping on SIGUSR1 to dump stacks, we wait on a Win32 event to be
// signaled. ACL'd to builtin administrators and local system
ev := "Global\\docker-daemon-" + fmt.Sprint(os.Getpid())
sd, err := winio.SddlToSecurityDescriptor("D:P(A;;GA;;;BA)(A;;GA;;;SY)")
if err != nil {
logrus.Errorf("failed to get security descriptor for debug stackdump event %s: %s", ev, err.Error())
return
}
var sa syscall.SecurityAttributes
sa.Length = uint32(unsafe.Sizeof(sa))
sa.InheritHandle = 1
sa.SecurityDescriptor = uintptr(unsafe.Pointer(&sd[0]))
h, err := system.CreateEvent(&sa, false, false, ev)
if h == 0 || err != nil {
logrus.Errorf("failed to create debug stackdump event %s: %s", ev, err.Error())
return
}
go func() {
logrus.Debugf("Stackdump - waiting signal at %s", ev)
for {
syscall.WaitForSingleObject(h, syscall.INFINITE)
signal.DumpStacks(root)
}
}()
}
func initSecurityAttributes() (*syscall.SecurityAttributes, error) {
// create security descriptor
sd := make([]byte, 4096)
if res, _, err := procInitializeSecurityDescriptor.Call(
uintptr(unsafe.Pointer(&sd[0])),
SECURITY_DESCRIPTOR_REVISION); int(res) == 0 {
return nil, os.NewSyscallError("InitializeSecurityDescriptor", err)
}
// configure security descriptor
present := 1
defaulted := 0
if res, _, err := procSetSecurityDescriptorDacl.Call(
uintptr(unsafe.Pointer(&sd[0])),
uintptr(present),
uintptr(unsafe.Pointer(nil)), // acl
uintptr(defaulted)); int(res) == 0 {
return nil, os.NewSyscallError("SetSecurityDescriptorDacl", err)
}
var sa syscall.SecurityAttributes
sa.Length = uint32(unsafe.Sizeof(sa))
sa.SecurityDescriptor = uintptr(unsafe.Pointer(&sd[0]))
return &sa, nil
}
// mkdirWithACL creates a new directory. If there is an error, it will be of
// type *PathError. .
//
// This is a modified and combined version of os.Mkdir and syscall.Mkdir
// in golang to cater for creating a directory am ACL permitting full
// access, with inheritance, to any subfolder/file for Built-in Administrators
// and Local System.
func mkdirWithACL(name string) error {
sa := syscall.SecurityAttributes{Length: 0}
sddl := "D:P(A;OICI;GA;;;BA)(A;OICI;GA;;;SY)"
sd, err := winio.SddlToSecurityDescriptor(sddl)
if err != nil {
return &os.PathError{"mkdir", name, err}
}
sa.Length = uint32(unsafe.Sizeof(sa))
sa.InheritHandle = 1
sa.SecurityDescriptor = uintptr(unsafe.Pointer(&sd[0]))
namep, err := syscall.UTF16PtrFromString(name)
if err != nil {
return &os.PathError{"mkdir", name, err}
}
e := syscall.CreateDirectory(namep, &sa)
if e != nil {
return &os.PathError{"mkdir", name, e}
}
return nil
}