lib/Object/ObjectFile.cpp

   1 //===- ObjectFile.cpp - File format independent object file ---------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines a file format independent ObjectFile class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Object/ObjectFile.h"
  15 #include "llvm/ADT/StringRef.h"
  16 #include "llvm/BinaryFormat/Magic.h"
  17 #include "llvm/Object/Binary.h"
  18 #include "llvm/Object/COFF.h"
  19 #include "llvm/Object/Error.h"
  20 #include "llvm/Object/MachO.h"
  21 #include "llvm/Object/Wasm.h"
  22 #include "llvm/Support/Error.h"
  23 #include "llvm/Support/ErrorHandling.h"
  24 #include "llvm/Support/ErrorOr.h"
  25 #include "llvm/Support/FileSystem.h"
  26 #include "llvm/Support/MemoryBuffer.h"
  27 #include "llvm/Support/raw_ostream.h"
  28 #include <algorithm>
  29 #include <cstdint>
  30 #include <memory>
  31 #include <system_error>
  32
  33 using namespace llvm;
  34 using namespace object;
  35
  36 void ObjectFile::anchor() {}
  37
  38 ObjectFile::ObjectFile(unsigned int Type, MemoryBufferRef Source)
  39     : SymbolicFile(Type, Source) {}
  40
  41 bool SectionRef::containsSymbol(SymbolRef S) const {
  42   Expected<section_iterator> SymSec = S.getSection();
  43   if (!SymSec) {
  44     // TODO: Actually report errors helpfully.
  45     consumeError(SymSec.takeError());
  46     return false;
  47   }
  48   return *this == **SymSec;
  49 }
  50
  51 uint64_t ObjectFile::getSymbolValue(DataRefImpl Ref) const {
  52   uint32_t Flags = getSymbolFlags(Ref);
  53   if (Flags & SymbolRef::SF_Undefined)
  54     return 0;
  55   if (Flags & SymbolRef::SF_Common)
  56     return getCommonSymbolSize(Ref);
  57   return getSymbolValueImpl(Ref);
  58 }
  59
  60 std::error_code ObjectFile::printSymbolName(raw_ostream &OS,
  61                                             DataRefImpl Symb) const {
  62   Expected<StringRef> Name = getSymbolName(Symb);
  63   if (!Name)
  64     return errorToErrorCode(Name.takeError());
  65   OS << *Name;
  66   return std::error_code();
  67 }
  68
  69 uint32_t ObjectFile::getSymbolAlignment(DataRefImpl DRI) const { return 0; }
  70
  71 bool ObjectFile::isSectionBitcode(DataRefImpl Sec) const {
  72   StringRef SectName;
  73   if (!getSectionName(Sec, SectName))
  74     return SectName == ".llvmbc";
  75   return false;
  76 }
  77
  78 bool ObjectFile::isSectionStripped(DataRefImpl Sec) const { return false; }
  79
  80 section_iterator ObjectFile::getRelocatedSection(DataRefImpl Sec) const {
  81   return section_iterator(SectionRef(Sec, this));
  82 }
  83
  84 Triple ObjectFile::makeTriple() const {
  85   Triple TheTriple;
  86   auto Arch = getArch();
  87   TheTriple.setArch(Triple::ArchType(Arch));
  88
  89   // For ARM targets, try to use the build attributes to build determine
  90   // the build target. Target features are also added, but later during
  91   // disassembly.
  92   if (Arch == Triple::arm || Arch == Triple::armeb)
  93     setARMSubArch(TheTriple);
  94
  95   // TheTriple defaults to ELF, and COFF doesn't have an environment:
  96   // the best we can do here is indicate that it is mach-o.
  97   if (isMachO())
  98     TheTriple.setObjectFormat(Triple::MachO);
  99
 100   if (isCOFF()) {
 101     const auto COFFObj = dyn_cast<COFFObjectFile>(this);
 102     if (COFFObj->getArch() == Triple::thumb)
 103       TheTriple.setTriple("thumbv7-windows");
 104   }
 105
 106   return TheTriple;
 107 }
 108
 109 Expected<std::unique_ptr<ObjectFile>>
 110 ObjectFile::createObjectFile(MemoryBufferRef Object, file_magic Type) {
 111   StringRef Data = Object.getBuffer();
 112   if (Type == file_magic::unknown)
 113     Type = identify_magic(Data);
 114
 115   switch (Type) {
 116   case file_magic::unknown:
 117   case file_magic::bitcode:
 118   case file_magic::coff_cl_gl_object:
 119   case file_magic::archive:
 120   case file_magic::macho_universal_binary:
 121   case file_magic::windows_resource:
 122   case file_magic::pdb:
 123     return errorCodeToError(object_error::invalid_file_type);
 124   case file_magic::elf:
 125   case file_magic::elf_relocatable:
 126   case file_magic::elf_executable:
 127   case file_magic::elf_shared_object:
 128   case file_magic::elf_core:
 129     return createELFObjectFile(Object);
 130   case file_magic::macho_object:
 131   case file_magic::macho_executable:
 132   case file_magic::macho_fixed_virtual_memory_shared_lib:
 133   case file_magic::macho_core:
 134   case file_magic::macho_preload_executable:
 135   case file_magic::macho_dynamically_linked_shared_lib:
 136   case file_magic::macho_dynamic_linker:
 137   case file_magic::macho_bundle:
 138   case file_magic::macho_dynamically_linked_shared_lib_stub:
 139   case file_magic::macho_dsym_companion:
 140   case file_magic::macho_kext_bundle:
 141     return createMachOObjectFile(Object);
 142   case file_magic::coff_object:
 143   case file_magic::coff_import_library:
 144   case file_magic::pecoff_executable:
 145     return createCOFFObjectFile(Object);
 146   case file_magic::wasm_object:
 147     return createWasmObjectFile(Object);
 148   }
 149   llvm_unreachable("Unexpected Object File Type");
 150 }
 151
 152 Expected<OwningBinary<ObjectFile>>
 153 ObjectFile::createObjectFile(StringRef ObjectPath) {
 154   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
 155       MemoryBuffer::getFile(ObjectPath);
 156   if (std::error_code EC = FileOrErr.getError())
 157     return errorCodeToError(EC);
 158   std::unique_ptr<MemoryBuffer> Buffer = std::move(FileOrErr.get());
 159
 160   Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
 161       createObjectFile(Buffer->getMemBufferRef());
 162   if (Error Err = ObjOrErr.takeError())
 163     return std::move(Err);
 164   std::unique_ptr<ObjectFile> Obj = std::move(ObjOrErr.get());
 165
 166   return OwningBinary<ObjectFile>(std::move(Obj), std::move(Buffer));
 167 }