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//===--- Overrides.cpp - Compat override table for Swift 5.0 runtime ------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file provides compatibility override hooks for Swift 5.0 runtimes.
//
//===----------------------------------------------------------------------===//
#include "Overrides.h"
#include "../Compatibility51/Overrides.h"
#include "CompatibilityOverride.h"
#include <dlfcn.h>
#include <mach-o/dyld.h>
#include <mach-o/getsect.h>
using namespace swift;
struct OverrideSection {
uintptr_t version;
#define OVERRIDE(name, ret, attrs, ccAttrs, namespace, typedArgs, namedArgs) \
Override_ ## name name;
#include "CompatibilityOverride.def"
};
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmissing-designated-field-initializers"
OverrideSection Swift50Overrides
__attribute__((used, section("__DATA,__swift_hooks"))) = {
.version = 0,
.conformsToProtocol = swift50override_conformsToProtocol,
// We use the same hook for conformsToSwiftProtocol as we do for a 5.1
// runtime, so reference the override from the Compatibility51 library.
// If we're back deploying to Swift 5.0, we also have to support 5.1, so
// the Compatibility51 library is always linked when the 50 library is.
.conformsToSwiftProtocol = swift51override_conformsToSwiftProtocol,
};
#pragma clang diagnostic pop
// Allow this library to get force-loaded by autolinking
__attribute__((weak, visibility("hidden")))
extern "C"
char _swift_FORCE_LOAD_$_swiftCompatibility50 = 0;
// Put a getClass hook in front of the system Swift runtime's hook to prevent it
// from trying to interpret symbolic references. rdar://problem/55036306
// FIXME: delete this #if and dlsym once we don't
// need to build with older libobjc headers
#if !OBJC_GETCLASSHOOK_DEFINED
using objc_hook_getClass = BOOL(*)(const char * _Nonnull name,
Class _Nullable * _Nonnull outClass);
#endif
static objc_hook_getClass OldGetClassHook;
static BOOL
getObjCClassByMangledName_untrusted(const char * _Nonnull typeName,
Class _Nullable * _Nonnull outClass) {
// Scan the string for byte sequences that might be recognized as
// symbolic references, and reject them.
for (const char *c = typeName; *c != 0; ++c) {
if (*c >= 1 && *c < 0x20) {
*outClass = Nil;
return NO;
}
}
if (OldGetClassHook) {
return OldGetClassHook(typeName, outClass);
}
// In case the OS runtime for some reason didn't install a hook, fallback to
// NO.
return NO;
}
#if __POINTER_WIDTH__ == 64
using mach_header_platform = mach_header_64;
#else
using mach_header_platform = mach_header;
#endif
__attribute__((constructor))
static void installGetClassHook_untrusted() {
extern char __dso_handle[];
// swiftCompatibility* might be linked into multiple dynamic libraries because
// of build system reasons, but the copy in the main executable is the only
// one that should count. Bail early unless we're running out of the main
// executable.
auto machHeader = (const mach_header_platform *)__dso_handle;
if (machHeader->filetype != MH_EXECUTE)
return;
// FIXME: delete this #if and dlsym once we don't
// need to build with older libobjc headers
#if !OBJC_GETCLASSHOOK_DEFINED
using objc_hook_getClass = BOOL(*)(const char * _Nonnull name,
Class _Nullable * _Nonnull outClass);
auto objc_setHook_getClass =
(void(*)(objc_hook_getClass _Nonnull,
objc_hook_getClass _Nullable * _Nonnull))
dlsym(RTLD_DEFAULT, "objc_setHook_getClass");
#endif
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunguarded-availability"
if (objc_setHook_getClass) {
objc_setHook_getClass(getObjCClassByMangledName_untrusted,
&OldGetClassHook);
}
#pragma clang diagnostic pop
}
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