mirror of
https://codeberg.org/ziglang/zig.git
synced 2026-04-26 13:01:34 +03:00
Alex Rønne Petersen
216 lines
12 KiB
C++
Vendored
216 lines
12 KiB
C++
Vendored
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___CONFIGURATION_HARDENING_H
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#define _LIBCPP___CONFIGURATION_HARDENING_H
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/* zig patch: instead of including __config_site, zig adds -D flags when compiling */
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#include <__configuration/experimental.h>
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#include <__configuration/language.h>
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#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
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# pragma GCC system_header
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#endif
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// TODO(LLVM 23): Remove this. We're making these an error to catch folks who might not have migrated.
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// Since hardening went through several changes (many of which impacted user-facing macros),
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// we're keeping these checks around for a bit longer than usual. Failure to properly configure
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// hardening results in checks being dropped silently, which is a pretty big deal.
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#if defined(_LIBCPP_ENABLE_ASSERTIONS)
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# error "_LIBCPP_ENABLE_ASSERTIONS has been removed, please use _LIBCPP_HARDENING_MODE=<mode> instead (see docs)"
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#endif
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#if defined(_LIBCPP_ENABLE_HARDENED_MODE)
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# error "_LIBCPP_ENABLE_HARDENED_MODE has been removed, please use _LIBCPP_HARDENING_MODE=<mode> instead (see docs)"
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#endif
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#if defined(_LIBCPP_ENABLE_SAFE_MODE)
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# error "_LIBCPP_ENABLE_SAFE_MODE has been removed, please use _LIBCPP_HARDENING_MODE=<mode> instead (see docs)"
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#endif
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#if defined(_LIBCPP_ENABLE_DEBUG_MODE)
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# error "_LIBCPP_ENABLE_DEBUG_MODE has been removed, please use _LIBCPP_HARDENING_MODE=<mode> instead (see docs)"
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#endif
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// The library provides the macro `_LIBCPP_HARDENING_MODE` which can be set to one of the following values:
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//
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// - `_LIBCPP_HARDENING_MODE_NONE`;
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// - `_LIBCPP_HARDENING_MODE_FAST`;
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// - `_LIBCPP_HARDENING_MODE_EXTENSIVE`;
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// - `_LIBCPP_HARDENING_MODE_DEBUG`.
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//
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// These values have the following effects:
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//
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// - `_LIBCPP_HARDENING_MODE_NONE` -- sets the hardening mode to "none" which disables all runtime hardening checks;
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//
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// - `_LIBCPP_HARDENING_MODE_FAST` -- sets that hardening mode to "fast". The fast mode enables security-critical checks
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// that can be done with relatively little runtime overhead in constant time;
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//
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// - `_LIBCPP_HARDENING_MODE_EXTENSIVE` -- sets the hardening mode to "extensive". The extensive mode is a superset of
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// the fast mode that additionally enables checks that are relatively cheap and prevent common types of logic errors
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// but are not necessarily security-critical;
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//
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// - `_LIBCPP_HARDENING_MODE_DEBUG` -- sets the hardening mode to "debug". The debug mode is a superset of the extensive
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// mode and enables all checks available in the library, including internal assertions. Checks that are part of the
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// debug mode can be very expensive and thus the debug mode is intended to be used for testing, not in production.
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// Inside the library, assertions are categorized so they can be cherry-picked based on the chosen hardening mode. These
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// macros are only for internal use -- users should only pick one of the high-level hardening modes described above.
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//
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// - `_LIBCPP_ASSERT_VALID_INPUT_RANGE` -- checks that ranges (whether expressed as an iterator pair, an iterator and
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// a sentinel, an iterator and a count, or a `std::range`) given as input to library functions are valid:
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// - the sentinel is reachable from the begin iterator;
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// - TODO(hardening): both iterators refer to the same container.
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//
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// - `_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS` -- checks that any attempts to access a container element, whether through
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// the container object or through an iterator, are valid and do not attempt to go out of bounds or otherwise access
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// a non-existent element. For iterator checks to work, bounded iterators must be enabled in the ABI. Types like
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// `optional` and `function` are considered one-element containers for the purposes of this check.
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//
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// - `_LIBCPP_ASSERT_NON_NULL` -- checks that the pointer being dereferenced is not null. On most modern platforms zero
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// address does not refer to an actual location in memory, so a null pointer dereference would not compromize the
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// memory security of a program (however, it is still undefined behavior that can result in strange errors due to
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// compiler optimizations).
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//
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// - `_LIBCPP_ASSERT_NON_OVERLAPPING_RANGES` -- for functions that take several ranges as arguments, checks that the
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// given ranges do not overlap.
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//
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// - `_LIBCPP_ASSERT_VALID_DEALLOCATION` -- checks that an attempt to deallocate memory is valid (e.g. the given object
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// was allocated by the given allocator). Violating this category typically results in a memory leak.
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//
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// - `_LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL` -- checks that a call to an external API doesn't fail in
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// an unexpected manner. This includes triggering documented cases of undefined behavior in an external library (like
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// attempting to unlock an unlocked mutex in pthreads). Any API external to the library falls under this category
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// (from system calls to compiler intrinsics). We generally don't expect these failures to compromize memory safety or
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// otherwise create an immediate security issue.
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//
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// - `_LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR` -- checks any operations that exchange nodes between containers to make sure
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// the containers have compatible allocators.
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//
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// - `_LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN` -- checks that the given argument is within the domain of valid arguments
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// for the function. Violating this typically produces an incorrect result (e.g. the clamp algorithm returns the
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// original value without clamping it due to incorrect functors) or puts an object into an invalid state (e.g.
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// a string view where only a subset of elements is possible to access). This category is for assertions violating
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// which doesn't cause any immediate issues in the library -- whatever the consequences are, they will happen in the
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// user code.
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//
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// - `_LIBCPP_ASSERT_PEDANTIC` -- checks prerequisites which are imposed by the Standard, but violating which happens to
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// be benign in our implementation.
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//
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// - `_LIBCPP_ASSERT_SEMANTIC_REQUIREMENT` -- checks that the given argument satisfies the semantic requirements imposed
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// by the Standard. Typically, there is no simple way to completely prove that a semantic requirement is satisfied;
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// thus, this would often be a heuristic check and it might be quite expensive.
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//
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// - `_LIBCPP_ASSERT_INTERNAL` -- checks that internal invariants of the library hold. These assertions don't depend on
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// user input.
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//
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// - `_LIBCPP_ASSERT_UNCATEGORIZED` -- for assertions that haven't been properly classified yet.
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// clang-format off
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# define _LIBCPP_HARDENING_MODE_NONE (1 << 1)
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# define _LIBCPP_HARDENING_MODE_FAST (1 << 2)
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# define _LIBCPP_HARDENING_MODE_EXTENSIVE (1 << 4) // Deliberately not ordered.
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# define _LIBCPP_HARDENING_MODE_DEBUG (1 << 3)
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// clang-format on
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#ifndef _LIBCPP_HARDENING_MODE
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# ifndef _LIBCPP_HARDENING_MODE_DEFAULT
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# error _LIBCPP_HARDENING_MODE_DEFAULT is not defined. This definition should be set at configuration time in the \
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`__config_site` header, please make sure your installation of libc++ is not broken.
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# endif
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# define _LIBCPP_HARDENING_MODE _LIBCPP_HARDENING_MODE_DEFAULT
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#endif
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#if _LIBCPP_HARDENING_MODE != _LIBCPP_HARDENING_MODE_NONE && _LIBCPP_HARDENING_MODE != _LIBCPP_HARDENING_MODE_FAST && \
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_LIBCPP_HARDENING_MODE != _LIBCPP_HARDENING_MODE_EXTENSIVE && \
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_LIBCPP_HARDENING_MODE != _LIBCPP_HARDENING_MODE_DEBUG
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# error _LIBCPP_HARDENING_MODE must be set to one of the following values: \
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_LIBCPP_HARDENING_MODE_NONE, \
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_LIBCPP_HARDENING_MODE_FAST, \
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_LIBCPP_HARDENING_MODE_EXTENSIVE, \
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_LIBCPP_HARDENING_MODE_DEBUG
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#endif
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// The library provides the macro `_LIBCPP_ASSERTION_SEMANTIC` for configuring the assertion semantic used by hardening;
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// it can be set to one of the following values:
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//
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// - `_LIBCPP_ASSERTION_SEMANTIC_IGNORE`;
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// - `_LIBCPP_ASSERTION_SEMANTIC_OBSERVE`;
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// - `_LIBCPP_ASSERTION_SEMANTIC_QUICK_ENFORCE`;
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// - `_LIBCPP_ASSERTION_SEMANTIC_ENFORCE`.
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//
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// libc++ assertion semantics generally mirror the evaluation semantics of C++26 Contracts:
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// - `ignore` evaluates the assertion but doesn't do anything if it fails (note that it differs from the Contracts
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// `ignore` semantic which wouldn't evaluate the assertion at all);
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// - `observe` logs an error (indicating, if possible, that the error is fatal) and continues execution;
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// - `quick-enforce` terminates the program as fast as possible (via trapping);
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// - `enforce` logs an error and then terminates the program.
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//
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// Additionally, a special `hardening-dependent` value selects the assertion semantic based on the hardening mode in
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// effect: the production-capable modes (`fast` and `extensive`) map to `quick_enforce` and the `debug` mode maps to
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// `enforce`. The `hardening-dependent` semantic cannot be selected explicitly, it is only used when no assertion
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// semantic is provided by the user _and_ the library's default semantic is configured to be dependent on hardening.
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//
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// Notes:
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// - Continuing execution after a hardening check fails results in undefined behavior; the `observe` semantic is meant
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// to make adopting hardening easier but should not be used outside of this scenario;
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// - C++26 wording for Library Hardening precludes a conforming Hardened implementation from using the Contracts
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// `ignore` semantic when evaluating hardened preconditions in the Library. Libc++ allows using this semantic for
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// hardened preconditions, however, be aware that using `ignore` does not produce a conforming "Hardened"
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// implementation, unlike the other semantics above.
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// clang-format off
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# define _LIBCPP_ASSERTION_SEMANTIC_HARDENING_DEPENDENT (1 << 1)
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# define _LIBCPP_ASSERTION_SEMANTIC_IGNORE (1 << 2)
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# define _LIBCPP_ASSERTION_SEMANTIC_OBSERVE (1 << 3)
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# define _LIBCPP_ASSERTION_SEMANTIC_QUICK_ENFORCE (1 << 4)
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# define _LIBCPP_ASSERTION_SEMANTIC_ENFORCE (1 << 5)
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// clang-format on
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// If the user attempts to configure the assertion semantic, check that it is allowed in the current environment.
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#if defined(_LIBCPP_ASSERTION_SEMANTIC)
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# if !_LIBCPP_HAS_EXPERIMENTAL_LIBRARY
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# error "Assertion semantics are an experimental feature."
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# endif
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# if defined(_LIBCPP_CXX03_LANG)
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# error "Assertion semantics are not available in the C++03 mode."
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# endif
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#endif // defined(_LIBCPP_ASSERTION_SEMANTIC)
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// User-provided semantic takes top priority -- don't override if set.
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#ifndef _LIBCPP_ASSERTION_SEMANTIC
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# ifndef _LIBCPP_ASSERTION_SEMANTIC_DEFAULT
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# error _LIBCPP_ASSERTION_SEMANTIC_DEFAULT is not defined. This definition should be set at configuration time in \
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the `__config_site` header, please make sure your installation of libc++ is not broken.
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# endif
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# if _LIBCPP_ASSERTION_SEMANTIC_DEFAULT != _LIBCPP_ASSERTION_SEMANTIC_HARDENING_DEPENDENT
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# define _LIBCPP_ASSERTION_SEMANTIC _LIBCPP_ASSERTION_SEMANTIC_DEFAULT
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# else
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# if _LIBCPP_HARDENING_MODE == _LIBCPP_HARDENING_MODE_DEBUG
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# define _LIBCPP_ASSERTION_SEMANTIC _LIBCPP_ASSERTION_SEMANTIC_ENFORCE
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# else
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# define _LIBCPP_ASSERTION_SEMANTIC _LIBCPP_ASSERTION_SEMANTIC_QUICK_ENFORCE
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# endif
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# endif // _LIBCPP_ASSERTION_SEMANTIC_DEFAULT != _LIBCPP_ASSERTION_SEMANTIC_HARDENING_DEPENDENT
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#endif // #ifndef _LIBCPP_ASSERTION_SEMANTIC
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// Finally, validate the selected semantic (in case the user tries setting it to an incorrect value):
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#if _LIBCPP_ASSERTION_SEMANTIC != _LIBCPP_ASSERTION_SEMANTIC_IGNORE && \
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_LIBCPP_ASSERTION_SEMANTIC != _LIBCPP_ASSERTION_SEMANTIC_OBSERVE && \
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_LIBCPP_ASSERTION_SEMANTIC != _LIBCPP_ASSERTION_SEMANTIC_QUICK_ENFORCE && \
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_LIBCPP_ASSERTION_SEMANTIC != _LIBCPP_ASSERTION_SEMANTIC_ENFORCE
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# error _LIBCPP_ASSERTION_SEMANTIC must be set to one of the following values: \
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_LIBCPP_ASSERTION_SEMANTIC_IGNORE, \
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_LIBCPP_ASSERTION_SEMANTIC_OBSERVE, \
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_LIBCPP_ASSERTION_SEMANTIC_QUICK_ENFORCE, \
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_LIBCPP_ASSERTION_SEMANTIC_ENFORCE
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#endif
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#endif // _LIBCPP___CONFIGURATION_HARDENING_H
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