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+/* -*- 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/. */
+
+/*
+ * JS allocation policies.
+ *
+ * The allocators here are for system memory with lifetimes which are not
+ * managed by the GC. See the comment at the top of vm/MallocProvider.h.
+ */
+
+#ifndef js_AllocPolicy_h
+#define js_AllocPolicy_h
+
+#include "js/TypeDecls.h"
+#include "js/Utility.h"
+
+extern MOZ_COLD JS_PUBLIC_API void JS_ReportOutOfMemory(JSContext* cx);
+
+namespace js {
+
+class FrontendContext;
+
+enum class AllocFunction { Malloc, Calloc, Realloc };
+
+/* Base class allocation policies providing allocation methods. */
+class AllocPolicyBase {
+ public:
+ template <typename T>
+ T* maybe_pod_arena_malloc(arena_id_t arenaId, size_t numElems) {
+ return js_pod_arena_malloc<T>(arenaId, numElems);
+ }
+ template <typename T>
+ T* maybe_pod_arena_calloc(arena_id_t arenaId, size_t numElems) {
+ return js_pod_arena_calloc<T>(arenaId, numElems);
+ }
+ template <typename T>
+ T* maybe_pod_arena_realloc(arena_id_t arenaId, T* p, size_t oldSize,
+ size_t newSize) {
+ return js_pod_arena_realloc<T>(arenaId, p, oldSize, newSize);
+ }
+ template <typename T>
+ T* pod_arena_malloc(arena_id_t arenaId, size_t numElems) {
+ return maybe_pod_arena_malloc<T>(arenaId, numElems);
+ }
+ template <typename T>
+ T* pod_arena_calloc(arena_id_t arenaId, size_t numElems) {
+ return maybe_pod_arena_calloc<T>(arenaId, numElems);
+ }
+ template <typename T>
+ T* pod_arena_realloc(arena_id_t arenaId, T* p, size_t oldSize,
+ size_t newSize) {
+ return maybe_pod_arena_realloc<T>(arenaId, p, oldSize, newSize);
+ }
+
+ template <typename T>
+ T* maybe_pod_malloc(size_t numElems) {
+ return maybe_pod_arena_malloc<T>(js::MallocArena, numElems);
+ }
+ template <typename T>
+ T* maybe_pod_calloc(size_t numElems) {
+ return maybe_pod_arena_calloc<T>(js::MallocArena, numElems);
+ }
+ template <typename T>
+ T* maybe_pod_realloc(T* p, size_t oldSize, size_t newSize) {
+ return maybe_pod_arena_realloc<T>(js::MallocArena, p, oldSize, newSize);
+ }
+ template <typename T>
+ T* pod_malloc(size_t numElems) {
+ return pod_arena_malloc<T>(js::MallocArena, numElems);
+ }
+ template <typename T>
+ T* pod_calloc(size_t numElems) {
+ return pod_arena_calloc<T>(js::MallocArena, numElems);
+ }
+ template <typename T>
+ T* pod_realloc(T* p, size_t oldSize, size_t newSize) {
+ return pod_arena_realloc<T>(js::MallocArena, p, oldSize, newSize);
+ }
+
+ template <typename T>
+ void free_(T* p, size_t numElems = 0) {
+ js_free(p);
+ }
+};
+
+/* Policy for using system memory functions and doing no error reporting. */
+class SystemAllocPolicy : public AllocPolicyBase {
+ public:
+ void reportAllocOverflow() const {}
+ bool checkSimulatedOOM() const { return !js::oom::ShouldFailWithOOM(); }
+};
+
+MOZ_COLD JS_PUBLIC_API void ReportOutOfMemory(JSContext* cx);
+MOZ_COLD JS_PUBLIC_API void ReportOutOfMemory(FrontendContext* fc);
+
+/*
+ * Allocation policy that calls the system memory functions and reports errors
+ * to the context. Since the JSContext given on construction is stored for
+ * the lifetime of the container, this policy may only be used for containers
+ * whose lifetime is a shorter than the given JSContext.
+ *
+ * FIXME bug 647103 - rewrite this in terms of temporary allocation functions,
+ * not the system ones.
+ */
+class JS_PUBLIC_API TempAllocPolicy : public AllocPolicyBase {
+ // Type tag for context_bits_
+ static constexpr uintptr_t JsContextTag = 0x1;
+
+ // Either a JSContext* (if JsContextTag is set), or FrontendContext*
+ uintptr_t const context_bits_;
+
+ MOZ_ALWAYS_INLINE bool hasJSContext() const {
+ return (context_bits_ & JsContextTag) == JsContextTag;
+ }
+
+ MOZ_ALWAYS_INLINE JSContext* cx() const {
+ MOZ_ASSERT(hasJSContext());
+ return reinterpret_cast<JSContext*>(context_bits_ ^ JsContextTag);
+ }
+
+ MOZ_ALWAYS_INLINE FrontendContext* fc() const {
+ MOZ_ASSERT(!hasJSContext());
+ return reinterpret_cast<FrontendContext*>(context_bits_);
+ }
+
+ /*
+ * Non-inline helper to call JSRuntime::onOutOfMemory with minimal
+ * code bloat.
+ */
+ void* onOutOfMemory(arena_id_t arenaId, AllocFunction allocFunc,
+ size_t nbytes, void* reallocPtr = nullptr);
+
+ template <typename T>
+ T* onOutOfMemoryTyped(arena_id_t arenaId, AllocFunction allocFunc,
+ size_t numElems, void* reallocPtr = nullptr) {
+ size_t bytes;
+ if (MOZ_UNLIKELY(!CalculateAllocSize<T>(numElems, &bytes))) {
+ return nullptr;
+ }
+ return static_cast<T*>(
+ onOutOfMemory(arenaId, allocFunc, bytes, reallocPtr));
+ }
+
+#ifdef DEBUG
+ void assertNotJSContextOnHelperThread() const;
+#else
+ MOZ_ALWAYS_INLINE void assertNotJSContextOnHelperThread() const {}
+#endif /* DEBUG */
+
+ public:
+ MOZ_IMPLICIT TempAllocPolicy(JSContext* cx)
+ : context_bits_(uintptr_t(cx) | JsContextTag) {
+ MOZ_ASSERT((uintptr_t(cx) & JsContextTag) == 0);
+ }
+ MOZ_IMPLICIT TempAllocPolicy(FrontendContext* fc)
+ : context_bits_(uintptr_t(fc)) {
+ MOZ_ASSERT((uintptr_t(fc) & JsContextTag) == 0);
+ }
+
+ template <typename T>
+ T* pod_arena_malloc(arena_id_t arenaId, size_t numElems) {
+ assertNotJSContextOnHelperThread();
+ T* p = this->maybe_pod_arena_malloc<T>(arenaId, numElems);
+ if (MOZ_UNLIKELY(!p)) {
+ p = onOutOfMemoryTyped<T>(arenaId, AllocFunction::Malloc, numElems);
+ }
+ return p;
+ }
+
+ template <typename T>
+ T* pod_arena_calloc(arena_id_t arenaId, size_t numElems) {
+ assertNotJSContextOnHelperThread();
+ T* p = this->maybe_pod_arena_calloc<T>(arenaId, numElems);
+ if (MOZ_UNLIKELY(!p)) {
+ p = onOutOfMemoryTyped<T>(arenaId, AllocFunction::Calloc, numElems);
+ }
+ return p;
+ }
+
+ template <typename T>
+ T* pod_arena_realloc(arena_id_t arenaId, T* prior, size_t oldSize,
+ size_t newSize) {
+ assertNotJSContextOnHelperThread();
+ T* p2 = this->maybe_pod_arena_realloc<T>(arenaId, prior, oldSize, newSize);
+ if (MOZ_UNLIKELY(!p2)) {
+ p2 = onOutOfMemoryTyped<T>(arenaId, AllocFunction::Realloc, newSize,
+ prior);
+ }
+ return p2;
+ }
+
+ template <typename T>
+ T* pod_malloc(size_t numElems) {
+ return pod_arena_malloc<T>(js::MallocArena, numElems);
+ }
+
+ template <typename T>
+ T* pod_calloc(size_t numElems) {
+ return pod_arena_calloc<T>(js::MallocArena, numElems);
+ }
+
+ template <typename T>
+ T* pod_realloc(T* prior, size_t oldSize, size_t newSize) {
+ return pod_arena_realloc<T>(js::MallocArena, prior, oldSize, newSize);
+ }
+
+ template <typename T>
+ void free_(T* p, size_t numElems = 0) {
+ js_free(p);
+ }
+
+ void reportAllocOverflow() const;
+
+ bool checkSimulatedOOM() const {
+ if (js::oom::ShouldFailWithOOM()) {
+ if (hasJSContext()) {
+ ReportOutOfMemory(cx());
+ } else {
+ ReportOutOfMemory(fc());
+ }
+ return false;
+ }
+
+ return true;
+ }
+};
+
+/*
+ * A replacement for MallocAllocPolicy that allocates in the JS heap and adds no
+ * extra behaviours.
+ *
+ * This is currently used for allocating source buffers for parsing. Since these
+ * are temporary and will not be freed by GC, the memory is not tracked by the
+ * usual accounting.
+ */
+class MallocAllocPolicy : public AllocPolicyBase {
+ public:
+ void reportAllocOverflow() const {}
+
+ [[nodiscard]] bool checkSimulatedOOM() const { return true; }
+};
+
+} /* namespace js */
+
+#endif /* js_AllocPolicy_h */