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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 */
/* JSPrincipals and related interfaces. */
#ifndef js_Principals_h
#define js_Principals_h
#include "mozilla/Atomics.h"
#include <stdint.h>
#include "jstypes.h"
#include "js/TypeDecls.h"
struct JSStructuredCloneReader;
struct JSStructuredCloneWriter;
struct JSPrincipals {
/* Don't call "destroy"; use reference counting macros below. */
mozilla::Atomic<int32_t, mozilla::SequentiallyConsistent> refcount{0};
#ifdef JS_DEBUG
/* A helper to facilitate principals debugging. */
uint32_t debugToken;
JSPrincipals() = default;
void setDebugToken(uint32_t token) {
#ifdef JS_DEBUG
debugToken = token;
* Write the principals with the given |writer|. Return false on failure,
* true on success.
virtual bool write(JSContext* cx, JSStructuredCloneWriter* writer) = 0;
* Whether the principal corresponds to a System or AddOn Principal.
* Technically this also checks for an ExpandedAddonPrincipal.
virtual bool isSystemOrAddonPrincipal() = 0;
* This is not defined by the JS engine but should be provided by the
* embedding.
JS_PUBLIC_API void dump();
extern JS_PUBLIC_API void JS_HoldPrincipals(JSPrincipals* principals);
extern JS_PUBLIC_API void JS_DropPrincipals(JSContext* cx,
JSPrincipals* principals);
// Return whether the first principal subsumes the second. The exact meaning of
// 'subsumes' is left up to the browser. Subsumption is checked inside the JS
// engine when determining, e.g., which stack frames to display in a backtrace.
typedef bool (*JSSubsumesOp)(JSPrincipals* first, JSPrincipals* second);
namespace JS {
enum class RuntimeCode { JS, WASM };
} // namespace JS
* Used to check if a CSP instance wants to disable eval() and friends.
* See JSContext::isRuntimeCodeGenEnabled() in vm/JSContext.cpp.
* `code` is the JavaScript source code passed to eval/Function, but nullptr
* for Wasm.
* Returning `false` from this callback will prevent the execution/compilation
* of the code.
typedef bool (*JSCSPEvalChecker)(JSContext* cx, JS::RuntimeCode kind,
JS::HandleString code);
struct JSSecurityCallbacks {
JSCSPEvalChecker contentSecurityPolicyAllows;
JSSubsumesOp subsumes;
extern JS_PUBLIC_API void JS_SetSecurityCallbacks(
JSContext* cx, const JSSecurityCallbacks* callbacks);
extern JS_PUBLIC_API const JSSecurityCallbacks* JS_GetSecurityCallbacks(
JSContext* cx);
* Code running with "trusted" principals will be given a deeper stack
* allocation than ordinary scripts. This allows trusted script to run after
* untrusted script has exhausted the stack. This function sets the
* runtime-wide trusted principal.
* This principals is not held (via JS_HoldPrincipals/JS_DropPrincipals).
* Instead, the caller must ensure that the given principals stays valid for as
* long as 'cx' may point to it. If the principals would be destroyed before
* 'cx', JS_SetTrustedPrincipals must be called again, passing nullptr for
* 'prin'.
extern JS_PUBLIC_API void JS_SetTrustedPrincipals(JSContext* cx,
JSPrincipals* prin);
typedef void (*JSDestroyPrincipalsOp)(JSPrincipals* principals);
* Initialize the callback that is called to destroy JSPrincipals instance
* when its reference counter drops to zero. The initialization can be done
* only once per JS runtime.
extern JS_PUBLIC_API void JS_InitDestroyPrincipalsCallback(
JSContext* cx, JSDestroyPrincipalsOp destroyPrincipals);
* Read a JSPrincipals instance from the given |reader| and initialize the out
* paratemer |outPrincipals| to the JSPrincipals instance read.
* Return false on failure, true on success. The |outPrincipals| parameter
* should not be modified if false is returned.
* The caller is not responsible for calling JS_HoldPrincipals on the resulting
* JSPrincipals instance, the JSReadPrincipalsOp must increment the refcount of
* the resulting JSPrincipals on behalf of the caller.
using JSReadPrincipalsOp = bool (*)(JSContext* cx,
JSStructuredCloneReader* reader,
JSPrincipals** outPrincipals);
* Initialize the callback that is called to read JSPrincipals instances from a
* buffer. The initialization can be done only once per JS runtime.
extern JS_PUBLIC_API void JS_InitReadPrincipalsCallback(
JSContext* cx, JSReadPrincipalsOp read);
namespace JS {
class MOZ_RAII AutoHoldPrincipals {
JSContext* cx_;
JSPrincipals* principals_ = nullptr;
explicit AutoHoldPrincipals(JSContext* cx, JSPrincipals* principals = nullptr)
: cx_(cx) {
~AutoHoldPrincipals() { reset(nullptr); }
void reset(JSPrincipals* principals) {
if (principals) {
if (principals_) {
JS_DropPrincipals(cx_, principals_);
principals_ = principals;
JSPrincipals* get() const { return principals_; }
} // namespace JS
#endif /* js_Principals_h */