/* -*- 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/. */
/* Implementations of runtime and static assertion macros for C and C++. */
// It appears that this is sometimes compiled without XP_WIN #ifdefined(_WIN32) # include <process.h> # define MOZ_GET_PID() _getpid() #elif !defined(__wasi__) # include <unistd.h> # define MOZ_GET_PID() getpid() #else // Prevent compiler warning # define MOZ_GET_PID() -1 #endif
/* * The crash reason set by MOZ_CRASH_ANNOTATE is consumed by the crash reporter * if present. It is declared here (and defined in Assertions.cpp) to make it * available to all code, even libraries that don't link with the crash reporter * directly.
*/
MOZ_BEGIN_EXTERN_C extern MFBT_DATA constchar* gMozCrashReason;
MOZ_END_EXTERN_C
#ifdefined(MOZ_HAS_MOZGLUE) || defined(MOZILLA_INTERNAL_API) staticinlinevoid AnnotateMozCrashReason(constchar* reason) {
gMozCrashReason = reason; // See bug 1681846, on 32-bit Android ARM the compiler removes the store to // gMozCrashReason if this barrier is not present. asmvolatile("" ::: "memory");
} # define MOZ_CRASH_ANNOTATE(...) AnnotateMozCrashReason(__VA_ARGS__) #else # define MOZ_CRASH_ANNOTATE(...) \ do { /* nothing */ \
} while (false) #endif
#include <stddef.h> #include <stdio.h> #include <stdlib.h> #ifdef _MSC_VER /* * TerminateProcess and GetCurrentProcess are defined in <winbase.h>, which * further depends on <windef.h>. We hardcode these few definitions manually * because those headers clutter the global namespace with a significant * number of undesired macros and symbols.
*/
MOZ_BEGIN_EXTERN_C
__declspec(dllimport) int __stdcall TerminateProcess(void* hProcess, unsignedint uExitCode);
__declspec(dllimport) void* __stdcall GetCurrentProcess(void);
MOZ_END_EXTERN_C #elifdefined(__wasi__) /* * On Wasm/WASI platforms, we just call __builtin_trap().
*/ #else # include <signal.h> #endif #ifdef ANDROID # include <android/log.h> #endif
/* * Prints |aStr| as an assertion failure (using aFilename and aLine as the * location of the assertion) to the standard debug-output channel. * * Usually you should use MOZ_ASSERT or MOZ_CRASH instead of this method. This * method is primarily for internal use in this header, and only secondarily * for use in implementing release-build assertions.
*/
/* * MOZ_ASSUME_UNREACHABLE_MARKER() expands to an expression which states that * it is undefined behavior for execution to reach this point. No guarantees * are made about what will happen if this is reached at runtime. Most code * should use MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE because it has extra * asserts.
*/ #ifdefined(__clang__) || defined(__GNUC__) # define MOZ_ASSUME_UNREACHABLE_MARKER() __builtin_unreachable() #elifdefined(_MSC_VER) # define MOZ_ASSUME_UNREACHABLE_MARKER() __assume(0) #else # ifdef __cplusplus # define MOZ_ASSUME_UNREACHABLE_MARKER() ::abort() # else # define MOZ_ASSUME_UNREACHABLE_MARKER() abort() # endif #endif
/** * MOZ_REALLY_CRASH is used in the implementation of MOZ_CRASH(). You should * call MOZ_CRASH instead.
*/ #ifdefined(_MSC_VER) /* * On MSVC use the __debugbreak compiler intrinsic, which produces an inline * (not nested in a system function) breakpoint. This distinctively invokes * Breakpad without requiring system library symbols on all stack-processing * machines, as a nested breakpoint would require. * * We use __LINE__ to prevent the compiler from folding multiple crash sites * together, which would make crash reports hard to understand. * * We use TerminateProcess with the exit code aborting would generate * because we don't want to invoke atexit handlers, destructors, library * unload handlers, and so on when our process might be in a compromised * state. * * We don't use abort() because it'd cause Windows to annoyingly pop up the * process error dialog multiple times. See bug 345118 and bug 426163. * * (Technically these are Windows requirements, not MSVC requirements. But * practically you need MSVC for debugging, and we only ship builds created * by MSVC, so doing it this way reduces complexity.)
*/
# define MOZ_REALLY_CRASH(line) \ do { \
MOZ_NOMERGE __debugbreak(); \
MOZ_NoReturn(line); \
} while (false)
#elif __wasi__
# define MOZ_REALLY_CRASH(line) __builtin_trap()
#else
/* * MOZ_CRASH_WRITE_ADDR is the address to be used when performing a forced * crash. NULL is preferred however if for some reason NULL cannot be used * this makes choosing another value possible. * * In the case of UBSan certain checks, bounds specifically, cause the compiler * to emit the 'ud2' instruction when storing to 0x0. This causes forced * crashes to manifest as ILL (at an arbitrary address) instead of the expected * SEGV at 0x0.
*/ # ifdef MOZ_UBSAN # define MOZ_CRASH_WRITE_ADDR 0x1 # else # define MOZ_CRASH_WRITE_ADDR NULL # endif
/* * MOZ_CRASH([explanation-string]) crashes the program, plain and simple, in a * Breakpad-compatible way, in both debug and release builds. * * MOZ_CRASH is a good solution for "handling" failure cases when you're * unwilling or unable to handle them more cleanly -- for OOM, for likely memory * corruption, and so on. It's also a good solution if you need safe behavior * in release builds as well as debug builds. But if the failure is one that * should be debugged and fixed, MOZ_ASSERT is generally preferable. * * The optional explanation-string, if provided, must be a string literal * explaining why we're crashing. This argument is intended for use with * MOZ_CRASH() calls whose rationale is non-obvious; don't use it if it's * obvious why we're crashing. * * If we're a DEBUG build and we crash at a MOZ_CRASH which provides an * explanation-string, we print the string to stderr. Otherwise, we don't * print anything; this is because we want MOZ_CRASH to be 100% safe in release * builds, and it's hard to print to stderr safely when memory might have been * corrupted.
*/ #if !(defined(DEBUG) || defined(FUZZING)) # define MOZ_CRASH(...) \ do { \
MOZ_FUZZING_HANDLE_CRASH_EVENT4("MOZ_CRASH", __FILE__, __LINE__, NULL); \
MOZ_CRASH_ANNOTATE("MOZ_CRASH(" __VA_ARGS__ ")"); \
MOZ_REALLY_CRASH(__LINE__); \
} while (false) #else # define MOZ_CRASH(...) \ do { \
MOZ_FUZZING_HANDLE_CRASH_EVENT4("MOZ_CRASH", __FILE__, __LINE__, NULL); \
MOZ_ReportCrash("" __VA_ARGS__, __FILE__, __LINE__); \
MOZ_CRASH_ANNOTATE("MOZ_CRASH(" __VA_ARGS__ ")"); \
MOZ_REALLY_CRASH(__LINE__); \
} while (false) #endif
/* * MOZ_DIAGNOSTIC_CRASH acts like MOZ_CRASH in a MOZ_DIAGNOSTIC_ASSERT_ENABLED * build, and does nothing otherwise. See the comment later in this file for a * description of when MOZ_DIAGNOSTIC_ASSERT_ENABLED is defined.
*/ #ifdefined(MOZ_DIAGNOSTIC_ASSERT_ENABLED) # define MOZ_DIAGNOSTIC_CRASH(...) MOZ_CRASH(__VA_ARGS__) #else # define MOZ_DIAGNOSTIC_CRASH(...) \ do { /* nothing */ \
} while (false) #endif
/* * MOZ_CRASH_UNSAFE(explanation-string) can be used if the explanation string * cannot be a string literal (but no other processing needs to be done on it). * A regular MOZ_CRASH() is preferred wherever possible, as passing arbitrary * strings from a potentially compromised process is not without risk. If the * string being passed is the result of a printf-style function, consider using * MOZ_CRASH_UNSAFE_PRINTF instead. * * @note This macro causes data collection because crash strings are annotated * to crash-stats and are publicly visible. Firefox data stewards must do data * review on usages of this macro.
*/ static MOZ_ALWAYS_INLINE_EVEN_DEBUG MOZ_COLD MOZ_NORETURN void MOZ_Crash( constchar* aFilename, int aLine, constchar* aReason) {
MOZ_FUZZING_HANDLE_CRASH_EVENT4("MOZ_CRASH", aFilename, aLine, aReason); #ifdefined(DEBUG) || defined(FUZZING)
MOZ_ReportCrash(aReason, aFilename, aLine); #endif
MOZ_CRASH_ANNOTATE(aReason);
MOZ_REALLY_CRASH(aLine);
} #define MOZ_CRASH_UNSAFE(reason) MOZ_Crash(__FILE__, __LINE__, reason)
/* * MOZ_CRASH_UNSAFE_PRINTF(format, arg1 [, args]) can be used when more * information is desired than a string literal can supply. The caller provides * a printf-style format string, which must be a string literal and between * 1 and 4 additional arguments. A regular MOZ_CRASH() is preferred wherever * possible, as passing arbitrary strings to printf from a potentially * compromised process is not without risk. * * @note This macro causes data collection because crash strings are annotated * to crash-stats and are publicly visible. Firefox data stewards must do data * review on usages of this macro.
*/ #define MOZ_CRASH_UNSAFE_PRINTF(format, ...) \ do { \
static_assert(MOZ_ARG_COUNT(__VA_ARGS__) > 0, \ "Did you forget arguments to MOZ_CRASH_UNSAFE_PRINTF? " \ "Or maybe you want MOZ_CRASH instead?"); \
static_assert(MOZ_ARG_COUNT(__VA_ARGS__) <= sPrintfMaxArgs, \ "Only up to 4 additional arguments are allowed!"); \
static_assert(sizeof(format) <= sPrintfCrashReasonSize, \ "The supplied format string is too long!"); \
MOZ_Crash(__FILE__, __LINE__, MOZ_CrashPrintf("" format, __VA_ARGS__)); \
} while (false)
MOZ_END_EXTERN_C
/* * MOZ_ASSERT(expr [, explanation-string]) asserts that |expr| must be truthy in * debug builds. If it is, execution continues. Otherwise, an error message * including the expression and the explanation-string (if provided) is printed, * an attempt is made to invoke any existing debugger, and execution halts. * MOZ_ASSERT is fatal: no recovery is possible. Do not assert a condition * which can correctly be falsy. * * The optional explanation-string, if provided, must be a string literal * explaining the assertion. It is intended for use with assertions whose * correctness or rationale is non-obvious, and for assertions where the "real" * condition being tested is best described prosaically. Don't provide an * explanation if it's not actually helpful. * * // No explanation needed: pointer arguments often must not be NULL. * MOZ_ASSERT(arg); * * // An explanation can be helpful to explain exactly how we know an * // assertion is valid. * MOZ_ASSERT(state == WAITING_FOR_RESPONSE, * "given that <thingA> and <thingB>, we must have..."); * * // Or it might disambiguate multiple identical (save for their location) * // assertions of the same expression. * MOZ_ASSERT(getSlot(PRIMITIVE_THIS_SLOT).isUndefined(), * "we already set [[PrimitiveThis]] for this Boolean object"); * MOZ_ASSERT(getSlot(PRIMITIVE_THIS_SLOT).isUndefined(), * "we already set [[PrimitiveThis]] for this String object"); * * MOZ_ASSERT has no effect in non-debug builds. It is designed to catch bugs * *only* during debugging, not "in the field". If you want the latter, use * MOZ_RELEASE_ASSERT, which applies to non-debug builds as well. * * MOZ_DIAGNOSTIC_ASSERT works like MOZ_RELEASE_ASSERT in Nightly and early beta * and MOZ_ASSERT in late Beta and Release - use this when a condition is * potentially rare enough to require real user testing to hit, but is not * security-sensitive. This can cause user pain, so use it sparingly. If a * MOZ_DIAGNOSTIC_ASSERT is firing, it should promptly be converted to a * MOZ_ASSERT while the failure is being investigated, rather than letting users * suffer. * * MOZ_DIAGNOSTIC_ASSERT_ENABLED is defined when MOZ_DIAGNOSTIC_ASSERT is like * MOZ_RELEASE_ASSERT rather than MOZ_ASSERT.
*/
/* * Implement MOZ_VALIDATE_ASSERT_CONDITION_TYPE, which is used to guard against * accidentally passing something unintended in lieu of an assertion condition.
*/
#ifdef __cplusplus # include <type_traits> namespace mozilla { namespace detail {
template <typename T> struct AssertionConditionType { using ValueT = std::remove_reference_t<T>;
static_assert(!std::is_array_v<ValueT>, "Expected boolean assertion condition, got an array or a " "string!");
static_assert(!std::is_function_v<ValueT>, "Expected boolean assertion condition, got a function! Did " "you intend to call that function?");
static_assert(!std::is_floating_point_v<ValueT>, "It's often a bad idea to assert that a floating-point number " "is nonzero, because such assertions tend to intermittently " "fail. Shouldn't your code gracefully handle this case instead " "of asserting? Anyway, if you really want to do that, write an " "explicit boolean condition, like !!x or x!=0.");
/* First the single-argument form. */ #define MOZ_ASSERT_HELPER1(kind, expr) \ do { \
MOZ_VALIDATE_ASSERT_CONDITION_TYPE(expr); \ if (MOZ_UNLIKELY(!MOZ_CHECK_ASSERT_ASSIGNMENT(expr))) { \
MOZ_FUZZING_HANDLE_CRASH_EVENT2(kind, #expr); \
MOZ_REPORT_ASSERTION_FAILURE(#expr, __FILE__, __LINE__); \
MOZ_CRASH_ANNOTATE(kind "("#expr")"); \
MOZ_REALLY_CRASH(__LINE__); \
} \
} while (false) /* Now the two-argument form. */ #define MOZ_ASSERT_HELPER2(kind, expr, explain) \ do { \
MOZ_VALIDATE_ASSERT_CONDITION_TYPE(expr); \ if (MOZ_UNLIKELY(!MOZ_CHECK_ASSERT_ASSIGNMENT(expr))) { \
MOZ_FUZZING_HANDLE_CRASH_EVENT2(kind, #expr); \
MOZ_REPORT_ASSERTION_FAILURE(#expr" (" explain ")", __FILE__, \
__LINE__); \
MOZ_CRASH_ANNOTATE(kind "("#expr") (" explain ")"); \
MOZ_REALLY_CRASH(__LINE__); \
} \
} while (false)
#define MOZ_ASSERT_GLUE(a, b) a b #define MOZ_RELEASE_ASSERT(...) \
MOZ_ASSERT_GLUE( \
MOZ_PASTE_PREFIX_AND_ARG_COUNT(MOZ_ASSERT_HELPER, __VA_ARGS__), \
("MOZ_RELEASE_ASSERT", __VA_ARGS__))
/* * MOZ_ASSERT_DEBUG_OR_FUZZING is like a MOZ_ASSERT but also enabled in builds * that are non-DEBUG but FUZZING. This is useful for checks that are too * expensive for Nightly in general but are still indicating potentially * critical bugs. * In fuzzing builds, the assert is rewritten to be a diagnostic assert because * we already use this in other sensitive places and fuzzing automation is * set to act on these under all circumstances.
*/ #ifdef FUZZING # define MOZ_ASSERT_DEBUG_OR_FUZZING(...) MOZ_DIAGNOSTIC_ASSERT(__VA_ARGS__) #else # define MOZ_ASSERT_DEBUG_OR_FUZZING(...) MOZ_ASSERT(__VA_ARGS__) #endif
/* * MOZ_ASSERT_IF(cond1, cond2) is equivalent to MOZ_ASSERT(cond2) if cond1 is * true. * * MOZ_ASSERT_IF(isPrime(num), num == 2 || isOdd(num)); * * As with MOZ_ASSERT, MOZ_ASSERT_IF has effect only in debug builds. It is * designed to catch bugs during debugging, not "in the field".
*/ #ifdef DEBUG # define MOZ_ASSERT_IF(cond, expr) \ do { \ if (cond) { \
MOZ_ASSERT(expr); \
} \
} while (false) #else # define MOZ_ASSERT_IF(cond, expr) \ do { /* nothing */ \
} while (false) #endif
/* * MOZ_DIAGNOSTIC_ASSERT_IF is like MOZ_ASSERT_IF, but using * MOZ_DIAGNOSTIC_ASSERT as the underlying assert. * * See the block comment for MOZ_DIAGNOSTIC_ASSERT above for more details on how * diagnostic assertions work and how to use them.
*/ #ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED # define MOZ_DIAGNOSTIC_ASSERT_IF(cond, expr) \ do { \ if (cond) { \
MOZ_DIAGNOSTIC_ASSERT(expr); \
} \
} while (false) #else # define MOZ_DIAGNOSTIC_ASSERT_IF(cond, expr) \ do { /* nothing */ \
} while (false) #endif
/* * MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE([reason]) tells the compiler that it * can assume that the macro call cannot be reached during execution. This lets * the compiler generate better-optimized code under some circumstances, at the * expense of the program's behavior being undefined if control reaches the * MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE. * * In Gecko, you probably should not use this macro outside of performance- or * size-critical code, because it's unsafe. If you don't care about code size * or performance, you should probably use MOZ_ASSERT or MOZ_CRASH. * * SpiderMonkey is a different beast, and there it's acceptable to use * MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE more widely. * * Note that MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE is noreturn, so it's valid * not to return a value following a MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE * call. * * Example usage: * * enum ValueType { * VALUE_STRING, * VALUE_INT, * VALUE_FLOAT * }; * * int ptrToInt(ValueType type, void* value) { * { * // We know for sure that type is either INT or FLOAT, and we want this * // code to run as quickly as possible. * switch (type) { * case VALUE_INT: * return *(int*) value; * case VALUE_FLOAT: * return (int) *(float*) value; * default: * MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE("Unexpected ValueType"); * } * }
*/
/* * Unconditional assert in debug builds for (assumed) unreachable code paths * that have a safe return without crashing in release builds.
*/ #define MOZ_ASSERT_UNREACHABLE(reason) \
MOZ_ASSERT(false, "MOZ_ASSERT_UNREACHABLE: " reason)
#define MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE(reason) \ do { \
MOZ_ASSERT_UNREACHABLE(reason); \
MOZ_ASSUME_UNREACHABLE_MARKER(); \
} while (false)
/** * MOZ_FALLTHROUGH_ASSERT is an annotation to suppress compiler warnings about * switch cases that MOZ_ASSERT(false) (or its alias MOZ_ASSERT_UNREACHABLE) in * debug builds, but intentionally fall through in release builds to handle * unexpected values. * * Why do we need MOZ_FALLTHROUGH_ASSERT in addition to [[fallthrough]]? In * release builds, the MOZ_ASSERT(false) will expand to `do { } while (false)`, * requiring a [[fallthrough]] annotation to suppress a -Wimplicit-fallthrough * warning. In debug builds, the MOZ_ASSERT(false) will expand to something like * `if (true) { MOZ_CRASH(); }` and the [[fallthrough]] annotation will cause * a -Wunreachable-code warning. The MOZ_FALLTHROUGH_ASSERT macro breaks this * warning stalemate. * * // Example before MOZ_FALLTHROUGH_ASSERT: * switch (foo) { * default: * // This case wants to assert in debug builds, fall through in release. * MOZ_ASSERT(false); // -Wimplicit-fallthrough warning in release builds! * [[fallthrough]]; // but -Wunreachable-code warning in debug builds! * case 5: * return 5; * } * * // Example with MOZ_FALLTHROUGH_ASSERT: * switch (foo) { * default: * // This case asserts in debug builds, falls through in release. * MOZ_FALLTHROUGH_ASSERT("Unexpected foo value?!"); * case 5: * return 5; * }
*/ #ifdef DEBUG # define MOZ_FALLTHROUGH_ASSERT(...) \
MOZ_CRASH("MOZ_FALLTHROUGH_ASSERT: " __VA_ARGS__) #else # define MOZ_FALLTHROUGH_ASSERT(...) [[fallthrough]] #endif
/* * MOZ_ALWAYS_TRUE(expr) and friends always evaluate the provided expression, in * both debug and release builds. Then, in debug builds and Nightly and early * beta builds, we crash using the string value of the expression as the message * using MOZ_DIAGNOSTIC_CRASH.
*/ #define MOZ_ALWAYS_TRUE(expr) \ do { \ if (MOZ_LIKELY(expr)) { \ /* Silence [[nodiscard]]. */ \
} else { \
MOZ_DIAGNOSTIC_CRASH(#expr); \
} \
} while (false)
/* * This is only used by Array and nsTArray classes, therefore it is not * required when included from C code.
*/ #ifdef __cplusplus namespace mozilla::detail {
MFBT_API MOZ_NORETURN MOZ_COLD void InvalidArrayIndex_CRASH(size_t aIndex,
size_t aLength);
} // namespace mozilla::detail #endif// __cplusplus
/* * Provide a fake default value to be used when a value is required but none can * sensibily be provided without adding undefined behavior or security issues. * * This function asserts and aborts if it ever executed. * * Example usage: * * class Trooper { * const Droid& lookFor; * Trooper() : lookFor(MakeCompilerAssumeUnreachableFakeValue< const Droid&>()) { * // The class might be instantiated due to existing caller * // but this never happens in practice. * } * }; *
*/ #ifdef __cplusplus namespace mozilla { template <typename T> staticinline T MakeCompilerAssumeUnreachableFakeValue() {
MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE();
}
} // namespace mozilla #endif// __cplusplus
#endif/* mozilla_Assertions_h */
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