chore: update gcr and docker cred helpers (#2910)

vendor/github.com/Microsoft/hcsshim/internal/winapi/utils.go

@@ -0,0 +1,82 @@
+//go:build windows
+
+package winapi
+
+import (
+	"errors"
+	"reflect"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+// Uint16BufferToSlice wraps a uint16 pointer-and-length into a slice
+// for easier interop with Go APIs
+func Uint16BufferToSlice(buffer *uint16, bufferLength int) (result []uint16) {
+	hdr := (*reflect.SliceHeader)(unsafe.Pointer(&result))
+	hdr.Data = uintptr(unsafe.Pointer(buffer))
+	hdr.Cap = bufferLength
+	hdr.Len = bufferLength
+
+	return
+}
+
+// UnicodeString corresponds to UNICODE_STRING win32 struct defined here
+// https://docs.microsoft.com/en-us/windows/win32/api/ntdef/ns-ntdef-_unicode_string
+type UnicodeString struct {
+	Length        uint16
+	MaximumLength uint16
+	Buffer        *uint16
+}
+
+// NTSTRSAFE_UNICODE_STRING_MAX_CCH is a constant defined in ntstrsafe.h. This value
+// denotes the maximum number of wide chars a path can have.
+const NTSTRSAFE_UNICODE_STRING_MAX_CCH = 32767
+
+// String converts a UnicodeString to a golang string
+func (uni UnicodeString) String() string {
+	// UnicodeString is not guaranteed to be null terminated, therefore
+	// use the UnicodeString's Length field
+	return windows.UTF16ToString(Uint16BufferToSlice(uni.Buffer, int(uni.Length/2)))
+}
+
+// NewUnicodeString allocates a new UnicodeString and copies `s` into
+// the buffer of the new UnicodeString.
+func NewUnicodeString(s string) (*UnicodeString, error) {
+	buf, err := windows.UTF16FromString(s)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(buf) > NTSTRSAFE_UNICODE_STRING_MAX_CCH {
+		return nil, syscall.ENAMETOOLONG
+	}
+
+	uni := &UnicodeString{
+		// The length is in bytes and should not include the trailing null character.
+		Length:        uint16((len(buf) - 1) * 2),
+		MaximumLength: uint16((len(buf) - 1) * 2),
+		Buffer:        &buf[0],
+	}
+	return uni, nil
+}
+
+// ConvertStringSetToSlice is a helper function used to convert the contents of
+// `buf` into a string slice. `buf` contains a set of null terminated strings
+// with an additional null at the end to indicate the end of the set.
+func ConvertStringSetToSlice(buf []byte) ([]string, error) {
+	var results []string
+	prev := 0
+	for i := range buf {
+		if buf[i] == 0 {
+			if prev == i {
+				// found two null characters in a row, return result
+				return results, nil
+			}
+			results = append(results, string(buf[prev:i]))
+			prev = i + 1
+		}
+	}
+	return nil, errors.New("string set malformed: missing null terminator at end of buffer")
+}