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ec7a926148
The async main drain queue function is noreturn, but was emitting a warning due to the override compatibility returning the result of the overridden function in the wrapper override function. To work around this, I've added the `OVERRIDE_TASK_NORETURN` macro, which provides an override point for noreturn functions in the concurrency library that doesn't return the result from the wrapped function, avoiding the warning. In the event that the function is not set, the macro is set to the normal `OVERRIDE` with the return type set to `void`.
104 lines
3.9 KiB
C++
104 lines
3.9 KiB
C++
//===--- CompatibilityOverride.cpp - Back-deploying compatibility fixes ---s-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Support back-deploying compatibility fixes for newer apps running on older runtimes.
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//
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//===----------------------------------------------------------------------===//
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#include "CompatibilityOverride.h"
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#ifdef SWIFT_STDLIB_SUPPORT_BACK_DEPLOYMENT
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#include "../runtime/ImageInspection.h"
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#include "swift/Runtime/Once.h"
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#include <assert.h>
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#include <atomic>
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#include <mach-o/getsect.h>
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#include <type_traits>
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using namespace swift;
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/// The definition of the contents of the override section.
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///
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/// The runtime looks in the main executable (not any libraries!) for a
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/// __swift54_hooks section and uses the hooks defined therein. This struct
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/// defines the layout of that section. These hooks allow extending
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/// runtime functionality when running apps built with a more recent
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/// compiler. If additional hooks are needed, they may be added at the
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/// end, but once ABI stability hits, existing ones must not be removed
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/// or rearranged. The version number at the beginning can be used to
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/// indicate the presence of added functions. Until we do so, the
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/// version must be set to 0.
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struct OverrideSection {
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uintptr_t version;
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#define OVERRIDE(name, ret, attrs, ccAttrs, namespace, typedArgs, namedArgs) \
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Override_ ## name name;
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#include COMPATIBILITY_OVERRIDE_INCLUDE_PATH
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};
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static_assert(std::is_pod<OverrideSection>::value,
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"OverrideSection has a set layout and must be POD.");
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// We only support mach-o for overrides, so the implementation of lookupSection
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// can be mach-o specific.
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#if __POINTER_WIDTH__ == 64
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using mach_header_platform = mach_header_64;
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#else
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using mach_header_platform = mach_header;
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#endif
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extern "C" mach_header_platform *_NSGetMachExecuteHeader();
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static void *lookupSection(const char *segment, const char *section,
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size_t *outSize) {
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unsigned long size;
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auto *executableHeader = _NSGetMachExecuteHeader();
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uint8_t *data = getsectiondata(executableHeader, segment, section, &size);
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if (outSize != nullptr && data != nullptr)
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*outSize = size;
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return static_cast<void *>(data);
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}
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static OverrideSection *getOverrideSectionPtr() {
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static OverrideSection *OverrideSectionPtr;
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static swift_once_t Predicate;
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swift_once(&Predicate, [](void *) {
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size_t Size;
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OverrideSectionPtr = static_cast<OverrideSection *>(
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lookupSection("__DATA", COMPATIBILITY_OVERRIDE_SECTION_NAME, &Size));
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if (Size < sizeof(OverrideSection))
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OverrideSectionPtr = nullptr;
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}, nullptr);
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return OverrideSectionPtr;
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}
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#define OVERRIDE(name, ret, attrs, ccAttrs, namespace, typedArgs, namedArgs) \
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Override_ ## name swift::getOverride_ ## name() { \
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auto *Section = getOverrideSectionPtr(); \
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if (Section == nullptr) \
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return nullptr; \
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return Section->name; \
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}
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#define OVERRIDE_NORETURN(name, attrs, ccAttrs, namespace, typedArgs, namedArgs) \
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Override_ ## name swift::getOverride_ ## name() { \
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auto *Section = getOverrideSectionPtr(); \
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if (Section == nullptr) \
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nullptr; \
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Section->name; \
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}
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#include COMPATIBILITY_OVERRIDE_INCLUDE_PATH
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#endif // #ifdef SWIFT_STDLIB_SUPPORT_BACK_DEPLOYMENT
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