snapshot: sagernet/gvisor v0.0.0-20250811.0-sing-box-mod.1

Содержимое пина, зафиксированного в go.mod sing-box-lx, одним коммитом
без истории. Полная история SagerNet/gvisor — 1.45 ГБ и клонируется в
каждой CI-джобе; наша дельта — одна вставка в одну функцию, история для
неё не нужна.

Module path github.com/sagernet/gvisor сохранён намеренно: на него
опирается replace-директива суперпроекта.

Патч поверх — отдельным коммитом, чтобы дельта читалась одним git show
и переносилась на новый пин копированием.

SPECS/TASKS/048-GVISOR_HANDSHAKE_NIL_CRASH

pkg/hostarch/sizes_util.go

@@ -0,0 +1,114 @@
+// Copyright 2022 The gVisor Authors.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+package hostarch
+
+// Masks often used when working with alignment in constant expressions.
+const (
+	PageMask      = PageSize - 1
+	HugePageMask  = HugePageSize - 1
+	CacheLineMask = CacheLineSize - 1
+)
+
+type bytecount interface {
+	~uint | ~uint16 | ~uint32 | ~uint64 | ~uintptr
+}
+
+type hugebytecount interface {
+	~uint | ~uint32 | ~uint64 | ~uintptr
+}
+
+// PageRoundDown returns x rounded down to the nearest multiple of PageSize.
+func PageRoundDown[T bytecount](x T) T {
+	return x &^ PageMask
+}
+
+// PageRoundUp returns x rounded up to the nearest multiple of PageSize. ok is
+// true iff rounding up does not overflow the range of T.
+func PageRoundUp[T bytecount](x T) (val T, ok bool) {
+	val = PageRoundDown(x + PageMask)
+	ok = val >= x
+	return
+}
+
+// MustPageRoundUp is equivalent to PageRoundUp, but panics if rounding up
+// overflows.
+func MustPageRoundUp[T bytecount](x T) T {
+	val, ok := PageRoundUp(x)
+	if !ok {
+		panic("PageRoundUp overflows")
+	}
+	return val
+}
+
+// PageOffset returns the offset of x into its containing page.
+func PageOffset[T bytecount](x T) T {
+	return x & PageMask
+}
+
+// IsPageAligned returns true if x is a multiple of PageSize.
+func IsPageAligned[T bytecount](x T) bool {
+	return PageOffset(x) == 0
+}
+
+// ToPagesRoundUp returns (the number of pages equal to x bytes rounded up,
+// true). If rounding x up to a multiple of PageSize overflows the range of T,
+// ToPagesRoundUp returns (unspecified, false).
+func ToPagesRoundUp[T bytecount](x T) (T, bool) {
+	y := x + PageMask
+	if y < x {
+		return x, false
+	}
+	return y / PageSize, true
+}
+
+// HugePageRoundDown returns x rounded down to the nearest multiple of
+// HugePageSize.
+func HugePageRoundDown[T hugebytecount](x T) T {
+	return x &^ HugePageMask
+}
+
+// HugePageRoundUp returns x rounded up to the nearest multiple of
+// HugePageSize. ok is true iff rounding up does not overflow the range of T.
+func HugePageRoundUp[T hugebytecount](x T) (val T, ok bool) {
+	val = HugePageRoundDown(x + HugePageMask)
+	ok = val >= x
+	return
+}
+
+// MustHugePageRoundUp is equivalent to HugePageRoundUp, but panics if rounding
+// up overflows.
+func MustHugePageRoundUp[T hugebytecount](x T) T {
+	val, ok := HugePageRoundUp(x)
+	if !ok {
+		panic("HugePageRoundUp overflows")
+	}
+	return val
+}
+
+// HugePageOffset returns the offset of x into its containing page.
+func HugePageOffset[T hugebytecount](x T) T {
+	return x & HugePageMask
+}
+
+// IsHugePageAligned returns true if x is a multiple of HugePageSize.
+func IsHugePageAligned[T hugebytecount](x T) bool {
+	return HugePageOffset(x) == 0
+}
+
+// CacheLineRoundDown returns the offset rounded down to the nearest multiple
+// of CacheLineSize.
+func CacheLineRoundDown[T bytecount](x T) T {
+	return x &^ CacheLineMask
+}
+
+// CacheLineRoundUp returns the offset rounded up to the nearest multiple of
+// CacheLineSize. ok is true iff rounding up does not overflow the range of T.
+func CacheLineRoundUp[T bytecount](x T) (val T, ok bool) {
+	val = CacheLineRoundDown(x + CacheLineMask)
+	ok = val >= x
+	return
+}