MachO/InputFiles.h - llvm-project/lld - Git at Google

 //===- InputFiles.h ---------------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLD_MACHO_INPUT_FILES_H
 #define LLD_MACHO_INPUT_FILES_H

 #include "MachOStructs.h"
 #include "Target.h"

 #include "lld/Common/LLVM.h"
 #include "lld/Common/Memory.h"
 #include "llvm/ADT/CachedHashString.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/BinaryFormat/MachO.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/TextAPI/TextAPIReader.h"

 #include <vector>

 namespace llvm {
 namespace lto {
 class InputFile;
 } // namespace lto
 namespace MachO {
 class InterfaceFile;
 } // namespace MachO
 class TarWriter;
 } // namespace llvm

 namespace lld {
 namespace macho {

 struct PlatformInfo;
 class ConcatInputSection;
 class Symbol;
 class Defined;
 struct Reloc;
 enum class RefState : uint8_t;

 // If --reproduce option is given, all input files are written
 // to this tar archive.
 extern std::unique_ptr<llvm::TarWriter> tar;

 // If .subsections_via_symbols is set, each InputSection will be split along
 // symbol boundaries. The field offset represents the offset of the subsection
 // from the start of the original pre-split InputSection.
 struct Subsection {
   uint64_t offset = 0;
   InputSection *isec = nullptr;
 };

 using Subsections = std::vector<Subsection>;

 struct Section {
   uint64_t address = 0;
   Subsections subsections;
   Section(uint64_t addr) : address(addr){};
 };

 class InputFile {
 public:
   enum Kind {
     ObjKind,
     OpaqueKind,
     DylibKind,
     ArchiveKind,
     BitcodeKind,
   };

   virtual ~InputFile() = default;
   Kind kind() const { return fileKind; }
   StringRef getName() const { return name; }
   static void resetIdCount() { idCount = 0; }

   MemoryBufferRef mb;

   std::vector<Symbol *> symbols;
   std::vector<Section> sections;
   // Provides an easy way to sort InputFiles deterministically.
   const int id;

   // If not empty, this stores the name of the archive containing this file.
   // We use this string for creating error messages.
   std::string archiveName;

 protected:
   InputFile(Kind kind, MemoryBufferRef mb)
       : mb(mb), id(idCount++), fileKind(kind), name(mb.getBufferIdentifier()) {}

   InputFile(Kind, const llvm::MachO::InterfaceFile &);

 private:
   const Kind fileKind;
   const StringRef name;

   static int idCount;
 };

 // .o file
 class ObjFile final : public InputFile {
 public:
   ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName);
   static bool classof(const InputFile *f) { return f->kind() == ObjKind; }

   llvm::DWARFUnit *compileUnit = nullptr;
   const uint32_t modTime;
   std::vector<ConcatInputSection *> debugSections;
   ArrayRef<llvm::MachO::data_in_code_entry> dataInCodeEntries;

 private:
   Section *compactUnwindSection = nullptr;

   template <class LP> void parse();
   template <class SectionHeader> void parseSections(ArrayRef<SectionHeader>);
   template <class LP>
   void parseSymbols(ArrayRef<typename LP::section> sectionHeaders,
                     ArrayRef<typename LP::nlist> nList, const char *strtab,
                     bool subsectionsViaSymbols);
   template <class NList>
   Symbol *parseNonSectionSymbol(const NList &sym, StringRef name);
   template <class SectionHeader>
   void parseRelocations(ArrayRef<SectionHeader> sectionHeaders,
                         const SectionHeader &, Subsections &);
   void parseDebugInfo();
   void parseDataInCode();
   void registerCompactUnwind();
 };

 // command-line -sectcreate file
 class OpaqueFile final : public InputFile {
 public:
   OpaqueFile(MemoryBufferRef mb, StringRef segName, StringRef sectName);
   static bool classof(const InputFile *f) { return f->kind() == OpaqueKind; }
 };

 // .dylib or .tbd file
 class DylibFile final : public InputFile {
 public:
   // Mach-O dylibs can re-export other dylibs as sub-libraries, meaning that the
   // symbols in those sub-libraries will be available under the umbrella
   // library's namespace. Those sub-libraries can also have their own
   // re-exports. When loading a re-exported dylib, `umbrella` should be set to
   // the root dylib to ensure symbols in the child library are correctly bound
   // to the root. On the other hand, if a dylib is being directly loaded
   // (through an -lfoo flag), then `umbrella` should be a nullptr.
   explicit DylibFile(MemoryBufferRef mb, DylibFile *umbrella,
                      bool isBundleLoader = false);
   explicit DylibFile(const llvm::MachO::InterfaceFile &interface,
                      DylibFile *umbrella = nullptr,
                      bool isBundleLoader = false);

   void parseLoadCommands(MemoryBufferRef mb);
   void parseReexports(const llvm::MachO::InterfaceFile &interface);

   static bool classof(const InputFile *f) { return f->kind() == DylibKind; }

   StringRef installName;
   DylibFile *exportingFile = nullptr;
   DylibFile *umbrella;
   SmallVector<StringRef, 2> rpaths;
   uint32_t compatibilityVersion = 0;
   uint32_t currentVersion = 0;
   int64_t ordinal = 0; // Ordinal numbering starts from 1, so 0 is a sentinel
   RefState refState;
   bool reexport = false;
   bool forceNeeded = false;
   bool forceWeakImport = false;
   bool deadStrippable = false;
   bool explicitlyLinked = false;

   unsigned numReferencedSymbols = 0;

   bool isReferenced() const { return numReferencedSymbols > 0; }

   // An executable can be used as a bundle loader that will load the output
   // file being linked, and that contains symbols referenced, but not
   // implemented in the bundle. When used like this, it is very similar
   // to a Dylib, so we re-used the same class to represent it.
   bool isBundleLoader;

 private:
   bool handleLDSymbol(StringRef originalName);
   void handleLDPreviousSymbol(StringRef name, StringRef originalName);
   void handleLDInstallNameSymbol(StringRef name, StringRef originalName);
   void checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const;
 };

 // .a file
 class ArchiveFile final : public InputFile {
 public:
   explicit ArchiveFile(std::unique_ptr<llvm::object::Archive> &&file);
   void addLazySymbols();
   void fetch(const llvm::object::Archive::Symbol &);
   // LLD normally doesn't use Error for error-handling, but the underlying
   // Archive library does, so this is the cleanest way to wrap it.
   Error fetch(const llvm::object::Archive::Child &, StringRef reason);
   const llvm::object::Archive &getArchive() const { return *file; };
   static bool classof(const InputFile *f) { return f->kind() == ArchiveKind; }

 private:
   std::unique_ptr<llvm::object::Archive> file;
   // Keep track of children fetched from the archive by tracking
   // which address offsets have been fetched already.
   llvm::DenseSet<uint64_t> seen;
 };

 class BitcodeFile final : public InputFile {
 public:
   explicit BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
                        uint64_t offsetInArchive);
   static bool classof(const InputFile *f) { return f->kind() == BitcodeKind; }

   std::unique_ptr<llvm::lto::InputFile> obj;
 };

 extern llvm::SetVector<InputFile *> inputFiles;
 extern llvm::DenseMap<llvm::CachedHashStringRef, MemoryBufferRef> cachedReads;

 llvm::Optional<MemoryBufferRef> readFile(StringRef path);

 namespace detail {

 template <class CommandType, class... Types>
 std::vector<const CommandType *>
 findCommands(const void *anyHdr, size_t maxCommands, Types... types) {
   std::vector<const CommandType *> cmds;
   std::initializer_list<uint32_t> typesList{types...};
   const auto *hdr = reinterpret_cast<const llvm::MachO::mach_header *>(anyHdr);
   const uint8_t *p =
       reinterpret_cast<const uint8_t *>(hdr) + target->headerSize;
   for (uint32_t i = 0, n = hdr->ncmds; i < n; ++i) {
     auto *cmd = reinterpret_cast<const CommandType *>(p);
     if (llvm::is_contained(typesList, cmd->cmd)) {
       cmds.push_back(cmd);
       if (cmds.size() == maxCommands)
         return cmds;
     }
     p += cmd->cmdsize;
   }
   return cmds;
 }

 } // namespace detail

 // anyHdr should be a pointer to either mach_header or mach_header_64
 template <class CommandType = llvm::MachO::load_command, class... Types>
 const CommandType *findCommand(const void *anyHdr, Types... types) {
   std::vector<const CommandType *> cmds =
       detail::findCommands<CommandType>(anyHdr, 1, types...);
   return cmds.size() ? cmds[0] : nullptr;
 }

 template <class CommandType = llvm::MachO::load_command, class... Types>
 std::vector<const CommandType *> findCommands(const void *anyHdr,
                                               Types... types) {
   return detail::findCommands<CommandType>(anyHdr, 0, types...);
 }

 } // namespace macho

 std::string toString(const macho::InputFile *file);
 } // namespace lld

 #endif
	//===- InputFiles.h ---------------------------------------------- C++ --===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLD_MACHO_INPUT_FILES_H
	#define LLD_MACHO_INPUT_FILES_H

	#include "MachOStructs.h"
	#include "Target.h"

	#include "lld/Common/LLVM.h"
	#include "lld/Common/Memory.h"
	#include "llvm/ADT/CachedHashString.h"
	#include "llvm/ADT/DenseSet.h"
	#include "llvm/ADT/SetVector.h"
	#include "llvm/BinaryFormat/MachO.h"
	#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
	#include "llvm/Object/Archive.h"
	#include "llvm/Support/MemoryBuffer.h"
	#include "llvm/TextAPI/TextAPIReader.h"

	#include <vector>

	namespace llvm {
	namespace lto {
	class InputFile;
	} // namespace lto
	namespace MachO {
	class InterfaceFile;
	} // namespace MachO
	class TarWriter;
	} // namespace llvm

	namespace lld {
	namespace macho {

	struct PlatformInfo;
	class ConcatInputSection;
	class Symbol;
	class Defined;
	struct Reloc;
	enum class RefState : uint8_t;

	// If --reproduce option is given, all input files are written
	// to this tar archive.
	extern std::unique_ptr<llvm::TarWriter> tar;

	// If .subsections_via_symbols is set, each InputSection will be split along
	// symbol boundaries. The field offset represents the offset of the subsection
	// from the start of the original pre-split InputSection.
	struct Subsection {
	uint64_t offset = 0;
	InputSection *isec = nullptr;
	};

	using Subsections = std::vector<Subsection>;

	struct Section {
	uint64_t address = 0;
	Subsections subsections;
	Section(uint64_t addr) : address(addr){};
	};

	class InputFile {
	public:
	enum Kind {
	ObjKind,
	OpaqueKind,
	DylibKind,
	ArchiveKind,
	BitcodeKind,
	};

	virtual ~InputFile() = default;
	Kind kind() const { return fileKind; }
	StringRef getName() const { return name; }
	static void resetIdCount() { idCount = 0; }

	MemoryBufferRef mb;

	std::vector<Symbol *> symbols;
	std::vector<Section> sections;
	// Provides an easy way to sort InputFiles deterministically.
	const int id;

	// If not empty, this stores the name of the archive containing this file.
	// We use this string for creating error messages.
	std::string archiveName;

	protected:
	InputFile(Kind kind, MemoryBufferRef mb)
	: mb(mb), id(idCount++), fileKind(kind), name(mb.getBufferIdentifier()) {}

	InputFile(Kind, const llvm::MachO::InterfaceFile &);

	private:
	const Kind fileKind;
	const StringRef name;

	static int idCount;
	};

	// .o file
	class ObjFile final : public InputFile {
	public:
	ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName);
	static bool classof(const InputFile *f) { return f->kind() == ObjKind; }

	llvm::DWARFUnit *compileUnit = nullptr;
	const uint32_t modTime;
	std::vector<ConcatInputSection *> debugSections;
	ArrayRef<llvm::MachO::data_in_code_entry> dataInCodeEntries;

	private:
	Section *compactUnwindSection = nullptr;

	template <class LP> void parse();
	template <class SectionHeader> void parseSections(ArrayRef<SectionHeader>);
	template <class LP>
	void parseSymbols(ArrayRef<typename LP::section> sectionHeaders,
	ArrayRef<typename LP::nlist> nList, const char *strtab,
	bool subsectionsViaSymbols);
	template <class NList>
	Symbol *parseNonSectionSymbol(const NList &sym, StringRef name);
	template <class SectionHeader>
	void parseRelocations(ArrayRef<SectionHeader> sectionHeaders,
	const SectionHeader &, Subsections &);
	void parseDebugInfo();
	void parseDataInCode();
	void registerCompactUnwind();
	};

	// command-line -sectcreate file
	class OpaqueFile final : public InputFile {
	public:
	OpaqueFile(MemoryBufferRef mb, StringRef segName, StringRef sectName);
	static bool classof(const InputFile *f) { return f->kind() == OpaqueKind; }
	};

	// .dylib or .tbd file
	class DylibFile final : public InputFile {
	public:
	// Mach-O dylibs can re-export other dylibs as sub-libraries, meaning that the
	// symbols in those sub-libraries will be available under the umbrella
	// library's namespace. Those sub-libraries can also have their own
	// re-exports. When loading a re-exported dylib, `umbrella` should be set to
	// the root dylib to ensure symbols in the child library are correctly bound
	// to the root. On the other hand, if a dylib is being directly loaded
	// (through an -lfoo flag), then `umbrella` should be a nullptr.
	explicit DylibFile(MemoryBufferRef mb, DylibFile *umbrella,
	bool isBundleLoader = false);
	explicit DylibFile(const llvm::MachO::InterfaceFile &interface,
	DylibFile *umbrella = nullptr,
	bool isBundleLoader = false);

	void parseLoadCommands(MemoryBufferRef mb);
	void parseReexports(const llvm::MachO::InterfaceFile &interface);

	static bool classof(const InputFile *f) { return f->kind() == DylibKind; }

	StringRef installName;
	DylibFile *exportingFile = nullptr;
	DylibFile *umbrella;
	SmallVector<StringRef, 2> rpaths;
	uint32_t compatibilityVersion = 0;
	uint32_t currentVersion = 0;
	int64_t ordinal = 0; // Ordinal numbering starts from 1, so 0 is a sentinel
	RefState refState;
	bool reexport = false;
	bool forceNeeded = false;
	bool forceWeakImport = false;
	bool deadStrippable = false;
	bool explicitlyLinked = false;

	unsigned numReferencedSymbols = 0;

	bool isReferenced() const { return numReferencedSymbols > 0; }

	// An executable can be used as a bundle loader that will load the output
	// file being linked, and that contains symbols referenced, but not
	// implemented in the bundle. When used like this, it is very similar
	// to a Dylib, so we re-used the same class to represent it.
	bool isBundleLoader;

	private:
	bool handleLDSymbol(StringRef originalName);
	void handleLDPreviousSymbol(StringRef name, StringRef originalName);
	void handleLDInstallNameSymbol(StringRef name, StringRef originalName);
	void checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const;
	};

	// .a file
	class ArchiveFile final : public InputFile {
	public:
	explicit ArchiveFile(std::unique_ptr<llvm::object::Archive> &&file);
	void addLazySymbols();
	void fetch(const llvm::object::Archive::Symbol &);
	// LLD normally doesn't use Error for error-handling, but the underlying
	// Archive library does, so this is the cleanest way to wrap it.
	Error fetch(const llvm::object::Archive::Child &, StringRef reason);
	const llvm::object::Archive &getArchive() const { return *file; };
	static bool classof(const InputFile *f) { return f->kind() == ArchiveKind; }

	private:
	std::unique_ptr<llvm::object::Archive> file;
	// Keep track of children fetched from the archive by tracking
	// which address offsets have been fetched already.
	llvm::DenseSet<uint64_t> seen;
	};

	class BitcodeFile final : public InputFile {
	public:
	explicit BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
	uint64_t offsetInArchive);
	static bool classof(const InputFile *f) { return f->kind() == BitcodeKind; }

	std::unique_ptr<llvm::lto::InputFile> obj;
	};

	extern llvm::SetVector<InputFile *> inputFiles;
	extern llvm::DenseMap<llvm::CachedHashStringRef, MemoryBufferRef> cachedReads;

	llvm::Optional<MemoryBufferRef> readFile(StringRef path);

	namespace detail {

	template <class CommandType, class... Types>
	std::vector<const CommandType *>
	findCommands(const void *anyHdr, size_t maxCommands, Types... types) {
	std::vector<const CommandType *> cmds;
	std::initializer_list<uint32_t> typesList{types...};
	const auto hdr = reinterpret_cast<const llvm::MachO::mach_header >(anyHdr);
	const uint8_t *p =
	reinterpret_cast<const uint8_t *>(hdr) + target->headerSize;
	for (uint32_t i = 0, n = hdr->ncmds; i < n; ++i) {
	auto cmd = reinterpret_cast<const CommandType >(p);
	if (llvm::is_contained(typesList, cmd->cmd)) {
	cmds.push_back(cmd);
	if (cmds.size() == maxCommands)
	return cmds;
	}
	p += cmd->cmdsize;
	}
	return cmds;
	}

	} // namespace detail

	// anyHdr should be a pointer to either mach_header or mach_header_64
	template <class CommandType = llvm::MachO::load_command, class... Types>
	const CommandType findCommand(const void anyHdr, Types... types) {
	std::vector<const CommandType *> cmds =
	detail::findCommands<CommandType>(anyHdr, 1, types...);
	return cmds.size() ? cmds[0] : nullptr;
	}

	template <class CommandType = llvm::MachO::load_command, class... Types>
	std::vector<const CommandType > findCommands(const void anyHdr,
	Types... types) {
	return detail::findCommands<CommandType>(anyHdr, 0, types...);
	}

	} // namespace macho

	std::string toString(const macho::InputFile *file);
	} // namespace lld

	#endif