- //===--- MetadataLookup.cpp - Swift Language Type Name Lookup -------------===//
- //
- // This source file is part of the Swift.org open source project
- //
- // Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
- // Licensed under Apache License v2.0 with Runtime Library Exception
- //
- // See http://swift.org/LICENSE.txt for license information
- // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
- //
- //===----------------------------------------------------------------------===//
- //
- // Implementations of runtime functions for looking up a type by name.
- //
- //===----------------------------------------------------------------------===//
-
- #include "swift/Basic/LLVM.h"
- #include "swift/Basic/Lazy.h"
- #include "swift/Runtime/Concurrent.h"
- #include "swift/Runtime/HeapObject.h"
- #include "swift/Runtime/Metadata.h"
- #include "llvm/ADT/DenseMap.h"
- #include "llvm/ADT/Optional.h"
- #include "llvm/ADT/PointerIntPair.h"
- #include "llvm/ADT/StringExtras.h"
- #include "Private.h"
-
- #if defined(__APPLE__) && defined(__MACH__)
- #include <mach-o/dyld.h>
- #include <mach-o/getsect.h>
- #elif defined(__ELF__)
- #include <elf.h>
- #include <link.h>
- #endif
-
- #include <dlfcn.h>
- #include <mutex>
-
- using namespace swift;
- using namespace Demangle;
-
- #if SWIFT_OBJC_INTEROP
- #include <objc/runtime.h>
- #include <objc/message.h>
- #include <objc/objc.h>
- #endif
-
- #if defined(__APPLE__) && defined(__MACH__)
- #define SWIFT_TYPE_METADATA_SECTION "__swift2_types"
- #elif defined(__ELF__)
- #define SWIFT_TYPE_METADATA_SECTION ".swift2_type_metadata_start"
- #endif
-
- // Type Metadata Cache.
-
- namespace {
- struct TypeMetadataSection {
- const TypeMetadataRecord *Begin, *End;
- const TypeMetadataRecord *begin() const {
- return Begin;
- }
- const TypeMetadataRecord *end() const {
- return End;
- }
- };
-
- struct TypeMetadataCacheEntry {
- private:
- std::string Name;
- const Metadata *Metadata;
-
- public:
- TypeMetadataCacheEntry(const llvm::StringRef name,
- const struct Metadata *metadata) {
- Name = name.str();
- Metadata = metadata;
- }
-
- bool matches(llvm::StringRef aName) {
- return aName.equals(Name);
- }
-
- const struct Metadata *getMetadata(void) {
- return Metadata;
- }
- };
- }
-
- static void _initializeCallbacksToInspectDylib();
-
- struct TypeMetadataState {
- ConcurrentMap<size_t, TypeMetadataCacheEntry> Cache;
- std::vector<TypeMetadataSection> SectionsToScan;
- pthread_mutex_t SectionsToScanLock;
-
- TypeMetadataState() {
- SectionsToScan.reserve(16);
- pthread_mutex_init(&SectionsToScanLock, nullptr);
- _initializeCallbacksToInspectDylib();
- }
- };
-
- static Lazy<TypeMetadataState> TypeMetadataRecords;
-
- static void
- _registerTypeMetadataRecords(TypeMetadataState &T,
- const TypeMetadataRecord *begin,
- const TypeMetadataRecord *end) {
- pthread_mutex_lock(&T.SectionsToScanLock);
- T.SectionsToScan.push_back(TypeMetadataSection{begin, end});
- pthread_mutex_unlock(&T.SectionsToScanLock);
- }
-
- static void _addImageTypeMetadataRecordsBlock(const uint8_t *records,
- size_t recordsSize) {
- assert(recordsSize % sizeof(TypeMetadataRecord) == 0
- && "weird-sized type metadata section?!");
-
- // If we have a section, enqueue the type metadata for lookup.
- auto recordsBegin
- = reinterpret_cast<const TypeMetadataRecord*>(records);
- auto recordsEnd
- = reinterpret_cast<const TypeMetadataRecord*>
- (records + recordsSize);
-
- // type metadata cache should always be sufficiently initialized by this point.
- _registerTypeMetadataRecords(TypeMetadataRecords.unsafeGetAlreadyInitialized(),
- recordsBegin, recordsEnd);
- }
-
- #if defined(__APPLE__) && defined(__MACH__)
- static void _addImageTypeMetadataRecords(const mach_header *mh,
- intptr_t vmaddr_slide) {
- #ifdef __LP64__
- using mach_header_platform = mach_header_64;
- assert(mh->magic == MH_MAGIC_64 && "loaded non-64-bit image?!");
- #else
- using mach_header_platform = mach_header;
- #endif
-
- // Look for a __swift2_types section.
- unsigned long recordsSize;
- const uint8_t *records =
- getsectiondata(reinterpret_cast<const mach_header_platform *>(mh),
- SEG_TEXT, SWIFT_TYPE_METADATA_SECTION,
- &recordsSize);
-
- if (!records)
- return;
-
- _addImageTypeMetadataRecordsBlock(records, recordsSize);
- }
- #elif defined(__ELF__)
- static int _addImageTypeMetadataRecords(struct dl_phdr_info *info,
- size_t size, void * /*data*/) {
- void *handle;
- if (!info->dlpi_name || info->dlpi_name[0] == '\0') {
- handle = dlopen(nullptr, RTLD_LAZY);
- } else
- handle = dlopen(info->dlpi_name, RTLD_LAZY | RTLD_NOLOAD);
- auto records = reinterpret_cast<const uint8_t*>(
- dlsym(handle, SWIFT_TYPE_METADATA_SECTION));
-
- if (!records) {
- // if there are no type metadata records, don't hold this handle open.
- dlclose(handle);
- return 0;
- }
-
- // Extract the size of the type metadata block from the head of the section
- auto recordsSize = *reinterpret_cast<const uint64_t*>(records);
- records += sizeof(recordsSize);
-
- _addImageTypeMetadataRecordsBlock(records, recordsSize);
-
- dlclose(handle);
- return 0;
- }
- #endif
-
- static void _initializeCallbacksToInspectDylib() {
- #if defined(__APPLE__) && defined(__MACH__)
- // Install our dyld callback.
- // Dyld will invoke this on our behalf for all images that have already
- // been loaded.
- _dyld_register_func_for_add_image(_addImageTypeMetadataRecords);
- #elif defined(__ELF__)
- // Search the loaded dls. Unlike the above, this only searches the already
- // loaded ones.
- // FIXME: Find a way to have this continue to happen after.
- // rdar://problem/19045112
- dl_iterate_phdr(_addImageTypeMetadataRecords, nullptr);
- #else
- # error No known mechanism to inspect dynamic libraries on this platform.
- #endif
- }
-
- void
- swift::swift_registerTypeMetadataRecords(const TypeMetadataRecord *begin,
- const TypeMetadataRecord *end) {
- auto &T = TypeMetadataRecords.get();
- _registerTypeMetadataRecords(T, begin, end);
- }
-
- // copied from ProtocolConformanceRecord::getCanonicalTypeMetadata()
- const Metadata *TypeMetadataRecord::getCanonicalTypeMetadata() const {
- switch (getTypeKind()) {
- case TypeMetadataRecordKind::UniqueDirectType:
- return getDirectType();
- case TypeMetadataRecordKind::NonuniqueDirectType:
- return swift_getForeignTypeMetadata((ForeignTypeMetadata *)getDirectType());
- case TypeMetadataRecordKind::UniqueDirectClass:
- if (auto *ClassMetadata =
- static_cast<const struct ClassMetadata *>(getDirectType()))
- return swift_getObjCClassMetadata(ClassMetadata);
- else
- return nullptr;
- default:
- return nullptr;
- }
- }
-
- // returns the type metadata if typeName matches the metadata's name
- const Metadata *
- swift::_matchMetadataByMangledTypeName(const llvm::StringRef typeName,
- const Metadata *metadata,
- const GenericMetadata *pattern) {
- const NominalTypeDescriptor *ntd = nullptr;
- const Metadata *foundMetadata = nullptr;
-
- if (metadata != nullptr)
- ntd = metadata->getNominalTypeDescriptor();
- else if (pattern != nullptr)
- ntd = pattern->getTemplateDescription();
-
- if (ntd == nullptr || ntd->Name != typeName)
- return nullptr;
-
- if (metadata != nullptr) {
- foundMetadata = metadata;
- } else if (!ntd->GenericParams.hasGenericParams()) {
- foundMetadata = swift_getResilientMetadata(const_cast<GenericMetadata *>(pattern));
- }
-
- return foundMetadata;
- }
-
- // finds the type metadata for the type named by typeName
- static const Metadata *
- _searchTypeMetadataRecords(const TypeMetadataState &T,
- const llvm::StringRef typeName) {
- unsigned sectionIdx = 0;
- unsigned endSectionIdx = T.SectionsToScan.size();
- const Metadata *foundMetadata = nullptr;
-
- for (; sectionIdx < endSectionIdx; ++sectionIdx) {
- auto §ion = T.SectionsToScan[sectionIdx];
- for (const auto &record : section) {
- if (auto metadata = record.getCanonicalTypeMetadata())
- foundMetadata = _matchMetadataByMangledTypeName(typeName, metadata, nullptr);
- else if (auto pattern = record.getGenericPattern())
- foundMetadata = _matchMetadataByMangledTypeName(typeName, nullptr, pattern);
-
- if (foundMetadata != nullptr)
- return foundMetadata;
- }
- }
-
- return nullptr;
- }
-
- static const Metadata *
- _typeByMangledName(const llvm::StringRef typeName) {
- const Metadata *foundMetadata = nullptr;
- auto &T = TypeMetadataRecords.get();
- size_t hash = llvm::HashString(typeName);
-
- ConcurrentList<TypeMetadataCacheEntry> &Bucket = T.Cache.findOrAllocateNode(hash);
-
- // Check name to type metadata cache
- for (auto &Entry : Bucket) {
- if (Entry.matches(typeName))
- return Entry.getMetadata();
- }
-
- // Check type metadata records
- pthread_mutex_lock(&T.SectionsToScanLock);
- foundMetadata = _searchTypeMetadataRecords(T, typeName);
- pthread_mutex_unlock(&T.SectionsToScanLock);
-
- // Check protocol conformances table. Note that this has no support for
- // resolving generic types yet.
- if (foundMetadata == nullptr)
- foundMetadata = _searchConformancesByMangledTypeName(typeName);
-
- if (foundMetadata != nullptr)
- Bucket.push_front(TypeMetadataCacheEntry(typeName, foundMetadata));
-
- #if SWIFT_OBJC_INTEROP
- // Check for ObjC class
- // FIXME does this have any value? any ObjC class with a Swift name
- // should already be registered as a Swift type.
- if (foundMetadata == nullptr) {
- std::string prefixedName("_Tt" + typeName.str());
- foundMetadata = reinterpret_cast<ClassMetadata *>
- (objc_lookUpClass(prefixedName.c_str()));
- }
- #endif
-
- return foundMetadata;
- }
-
- /// Return the type metadata for a given mangled name, used in the
- /// implementation of _typeByName(). The human readable name returned
- /// by swift_getTypeName() is non-unique, so we used mangled names
- /// internally.
- extern "C"
- const Metadata *
- swift_getTypeByMangledName(const char *typeName, size_t typeNameLength) {
- llvm::StringRef name(typeName, typeNameLength);
- return _typeByMangledName(name);
- }
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