1 files changed, 165 insertions, 0 deletions
diff --git a/js/public/friend/StackLimits.h b/js/public/friend/StackLimits.h
new file mode 100644
index 0000000000..57168d222f
--- /dev/null
+++ b/js/public/friend/StackLimits.h
@@ -0,0 +1,165 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef js_friend_StackLimits_h
+#define js_friend_StackLimits_h
+
+#include "mozilla/Attributes.h"  // MOZ_ALWAYS_INLINE, MOZ_COLD
+#include "mozilla/Likely.h"      // MOZ_LIKELY
+
+#include <stddef.h>  // size_t
+#include <stdint.h>  // uintptr_t
+
+#include "jstypes.h"  // JS_FRIEND_API
+
+#include "js/HeapAPI.h"  // JS::StackKind, JS::StackForTrustedScript, JS::StackForUntrustedScript
+#include "js/RootingAPI.h"  // JS::RootingContext
+#include "js/Utility.h"  // JS_STACK_OOM_POSSIBLY_FAIL_REPORT, JS_STACK_OOM_POSSIBLY_FAIL
+
+struct JS_PUBLIC_API JSContext;
+
+#ifndef JS_STACK_GROWTH_DIRECTION
+#  ifdef __hppa
+#    define JS_STACK_GROWTH_DIRECTION (1)
+#  else
+#    define JS_STACK_GROWTH_DIRECTION (-1)
+#  endif
+#endif
+
+#if JS_STACK_GROWTH_DIRECTION > 0
+#  define JS_CHECK_STACK_SIZE(limit, sp) (MOZ_LIKELY((uintptr_t)(sp) < (limit)))
+#else
+#  define JS_CHECK_STACK_SIZE(limit, sp) (MOZ_LIKELY((uintptr_t)(sp) > (limit)))
+#endif
+
+namespace js {
+
+namespace detail {
+
+extern JS_FRIEND_API bool RunningWithTrustedPrincipals(JSContext* cx);
+
+MOZ_ALWAYS_INLINE uintptr_t GetNativeStackLimitHelper(JSContext* cx,
+                                                      JS::StackKind kind,
+                                                      int extraAllowance) {
+  uintptr_t limit = JS::RootingContext::get(cx)->nativeStackLimit[kind];
+#if JS_STACK_GROWTH_DIRECTION > 0
+  limit += extraAllowance;
+#else
+  limit -= extraAllowance;
+#endif
+  return limit;
+}
+
+}  // namespace detail
+
+extern MOZ_COLD JS_FRIEND_API void ReportOverRecursed(JSContext* maybecx);
+
+MOZ_ALWAYS_INLINE uintptr_t GetNativeStackLimit(JSContext* cx) {
+  JS::StackKind kind = detail::RunningWithTrustedPrincipals(cx)
+                           ? JS::StackForTrustedScript
+                           : JS::StackForUntrustedScript;
+  return detail::GetNativeStackLimitHelper(cx, kind, 0);
+}
+
+/*
+ * These functions return |false| if we are close to using up the C++ stack.
+ * They also report an overrecursion error, except for the DontReport variants.
+ * The CheckSystemRecursionLimit variant gives us a little extra space so we
+ * can ensure that crucial code is able to run. CheckRecursionLimitConservative
+ * allows less space than any other check, including a safety buffer (as in, it
+ * uses the untrusted limit and subtracts a little more from it).
+ */
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimit(JSContext* cx, uintptr_t limit) {
+  int stackDummy;
+
+  JS_STACK_OOM_POSSIBLY_FAIL_REPORT();
+
+  if (!JS_CHECK_STACK_SIZE(limit, &stackDummy)) {
+    ReportOverRecursed(cx);
+    return false;
+  }
+
+  return true;
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimitDontReport(uintptr_t limit) {
+  int stackDummy;
+
+  JS_STACK_OOM_POSSIBLY_FAIL();
+
+  return JS_CHECK_STACK_SIZE(limit, &stackDummy);
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimit(JSContext* cx) {
+  JS_STACK_OOM_POSSIBLY_FAIL_REPORT();
+
+  // GetNativeStackLimit(cx) is pretty slow because it has to do an uninlined
+  // call to RunningWithTrustedPrincipals to determine which stack limit to
+  // use. To work around this, check the untrusted limit first to avoid the
+  // overhead in most cases.
+  uintptr_t untrustedLimit =
+      detail::GetNativeStackLimitHelper(cx, JS::StackForUntrustedScript, 0);
+  if (MOZ_LIKELY(CheckRecursionLimitDontReport(untrustedLimit))) {
+    return true;
+  }
+  return CheckRecursionLimit(cx, GetNativeStackLimit(cx));
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimitDontReport(JSContext* cx) {
+  return CheckRecursionLimitDontReport(GetNativeStackLimit(cx));
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimitWithStackPointerDontReport(
+    JSContext* cx, void* sp) {
+  JS_STACK_OOM_POSSIBLY_FAIL();
+
+  return JS_CHECK_STACK_SIZE(GetNativeStackLimit(cx), sp);
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimitWithStackPointer(JSContext* cx,
+                                                           void* sp) {
+  JS_STACK_OOM_POSSIBLY_FAIL_REPORT();
+
+  if (!JS_CHECK_STACK_SIZE(GetNativeStackLimit(cx), sp)) {
+    ReportOverRecursed(cx);
+    return false;
+  }
+  return true;
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimitWithExtra(JSContext* cx,
+                                                    size_t extra) {
+  char stackDummy;
+  char* sp = &stackDummy;
+#if JS_STACK_GROWTH_DIRECTION > 0
+  sp += extra;
+#else
+  sp -= extra;
+#endif
+  return CheckRecursionLimitWithStackPointer(cx, sp);
+}
+
+MOZ_ALWAYS_INLINE bool CheckSystemRecursionLimit(JSContext* cx) {
+  return CheckRecursionLimit(
+      cx, detail::GetNativeStackLimitHelper(cx, JS::StackForSystemCode, 0));
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimitConservative(JSContext* cx) {
+  return CheckRecursionLimit(
+      cx, detail::GetNativeStackLimitHelper(cx, JS::StackForUntrustedScript,
+                                            -1024 * int(sizeof(size_t))));
+}
+
+MOZ_ALWAYS_INLINE bool CheckRecursionLimitConservativeDontReport(
+    JSContext* cx) {
+  return CheckRecursionLimitDontReport(detail::GetNativeStackLimitHelper(
+      cx, JS::StackForUntrustedScript, -1024 * int(sizeof(size_t))));
+}
+
+}  // namespace js
+
+#endif  // js_friend_StackLimits_h