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      1 //===- ObjectFile.cpp - File format independent object file ---------------===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 // This file defines a file format independent ObjectFile class.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #include "llvm/Object/ObjectFile.h"
     14 #include "llvm/ADT/StringRef.h"
     15 #include "llvm/BinaryFormat/Magic.h"
     16 #include "llvm/Object/Binary.h"
     17 #include "llvm/Object/COFF.h"
     18 #include "llvm/Object/Error.h"
     19 #include "llvm/Object/MachO.h"
     20 #include "llvm/Object/Wasm.h"
     21 #include "llvm/Support/Error.h"
     22 #include "llvm/Support/ErrorHandling.h"
     23 #include "llvm/Support/ErrorOr.h"
     24 #include "llvm/Support/FileSystem.h"
     25 #include "llvm/Support/MemoryBuffer.h"
     26 #include "llvm/Support/raw_ostream.h"
     27 #include <algorithm>
     28 #include <cstdint>
     29 #include <memory>
     30 #include <system_error>
     31 
     32 using namespace llvm;
     33 using namespace object;
     34 
     35 raw_ostream &object::operator<<(raw_ostream &OS, const SectionedAddress &Addr) {
     36   OS << "SectionedAddress{" << format_hex(Addr.Address, 10);
     37   if (Addr.SectionIndex != SectionedAddress::UndefSection)
     38     OS << ", " << Addr.SectionIndex;
     39   return OS << "}";
     40 }
     41 
     42 void ObjectFile::anchor() {}
     43 
     44 ObjectFile::ObjectFile(unsigned int Type, MemoryBufferRef Source)
     45     : SymbolicFile(Type, Source) {}
     46 
     47 bool SectionRef::containsSymbol(SymbolRef S) const {
     48   Expected<section_iterator> SymSec = S.getSection();
     49   if (!SymSec) {
     50     // TODO: Actually report errors helpfully.
     51     consumeError(SymSec.takeError());
     52     return false;
     53   }
     54   return *this == **SymSec;
     55 }
     56 
     57 Expected<uint64_t> ObjectFile::getSymbolValue(DataRefImpl Ref) const {
     58   if (Expected<uint32_t> FlagsOrErr = getSymbolFlags(Ref)) {
     59     if (*FlagsOrErr & SymbolRef::SF_Undefined)
     60       return 0;
     61     if (*FlagsOrErr & SymbolRef::SF_Common)
     62       return getCommonSymbolSize(Ref);
     63   } else
     64     // TODO: Test this error.
     65     return FlagsOrErr.takeError();
     66   return getSymbolValueImpl(Ref);
     67 }
     68 
     69 Error ObjectFile::printSymbolName(raw_ostream &OS, DataRefImpl Symb) const {
     70   Expected<StringRef> Name = getSymbolName(Symb);
     71   if (!Name)
     72     return Name.takeError();
     73   OS << *Name;
     74   return Error::success();
     75 }
     76 
     77 uint32_t ObjectFile::getSymbolAlignment(DataRefImpl DRI) const { return 0; }
     78 
     79 bool ObjectFile::isSectionBitcode(DataRefImpl Sec) const {
     80   Expected<StringRef> NameOrErr = getSectionName(Sec);
     81   if (NameOrErr)
     82     return *NameOrErr == ".llvmbc";
     83   consumeError(NameOrErr.takeError());
     84   return false;
     85 }
     86 
     87 bool ObjectFile::isSectionStripped(DataRefImpl Sec) const { return false; }
     88 
     89 bool ObjectFile::isBerkeleyText(DataRefImpl Sec) const {
     90   return isSectionText(Sec);
     91 }
     92 
     93 bool ObjectFile::isBerkeleyData(DataRefImpl Sec) const {
     94   return isSectionData(Sec);
     95 }
     96 
     97 bool ObjectFile::isDebugSection(StringRef SectionName) const {
     98   return false;
     99 }
    100 
    101 Expected<section_iterator>
    102 ObjectFile::getRelocatedSection(DataRefImpl Sec) const {
    103   return section_iterator(SectionRef(Sec, this));
    104 }
    105 
    106 Triple ObjectFile::makeTriple() const {
    107   Triple TheTriple;
    108   auto Arch = getArch();
    109   TheTriple.setArch(Triple::ArchType(Arch));
    110 
    111   // For ARM targets, try to use the build attributes to build determine
    112   // the build target. Target features are also added, but later during
    113   // disassembly.
    114   if (Arch == Triple::arm || Arch == Triple::armeb)
    115     setARMSubArch(TheTriple);
    116 
    117   // TheTriple defaults to ELF, and COFF doesn't have an environment:
    118   // something we can do here is indicate that it is mach-o.
    119   if (isMachO()) {
    120     TheTriple.setObjectFormat(Triple::MachO);
    121   } else if (isCOFF()) {
    122     const auto COFFObj = cast<COFFObjectFile>(this);
    123     if (COFFObj->getArch() == Triple::thumb)
    124       TheTriple.setTriple("thumbv7-windows");
    125   } else if (isXCOFF()) {
    126     // XCOFF implies AIX.
    127     TheTriple.setOS(Triple::AIX);
    128     TheTriple.setObjectFormat(Triple::XCOFF);
    129   }
    130 
    131   return TheTriple;
    132 }
    133 
    134 Expected<std::unique_ptr<ObjectFile>>
    135 ObjectFile::createObjectFile(MemoryBufferRef Object, file_magic Type,
    136                              bool InitContent) {
    137   StringRef Data = Object.getBuffer();
    138   if (Type == file_magic::unknown)
    139     Type = identify_magic(Data);
    140 
    141   switch (Type) {
    142   case file_magic::unknown:
    143   case file_magic::bitcode:
    144   case file_magic::coff_cl_gl_object:
    145   case file_magic::archive:
    146   case file_magic::macho_universal_binary:
    147   case file_magic::windows_resource:
    148   case file_magic::pdb:
    149   case file_magic::minidump:
    150     return errorCodeToError(object_error::invalid_file_type);
    151   case file_magic::tapi_file:
    152     return errorCodeToError(object_error::invalid_file_type);
    153   case file_magic::elf:
    154   case file_magic::elf_relocatable:
    155   case file_magic::elf_executable:
    156   case file_magic::elf_shared_object:
    157   case file_magic::elf_core:
    158     return createELFObjectFile(Object, InitContent);
    159   case file_magic::macho_object:
    160   case file_magic::macho_executable:
    161   case file_magic::macho_fixed_virtual_memory_shared_lib:
    162   case file_magic::macho_core:
    163   case file_magic::macho_preload_executable:
    164   case file_magic::macho_dynamically_linked_shared_lib:
    165   case file_magic::macho_dynamic_linker:
    166   case file_magic::macho_bundle:
    167   case file_magic::macho_dynamically_linked_shared_lib_stub:
    168   case file_magic::macho_dsym_companion:
    169   case file_magic::macho_kext_bundle:
    170     return createMachOObjectFile(Object);
    171   case file_magic::coff_object:
    172   case file_magic::coff_import_library:
    173   case file_magic::pecoff_executable:
    174     return createCOFFObjectFile(Object);
    175   case file_magic::xcoff_object_32:
    176     return createXCOFFObjectFile(Object, Binary::ID_XCOFF32);
    177   case file_magic::xcoff_object_64:
    178     return createXCOFFObjectFile(Object, Binary::ID_XCOFF64);
    179   case file_magic::wasm_object:
    180     return createWasmObjectFile(Object);
    181   }
    182   llvm_unreachable("Unexpected Object File Type");
    183 }
    184 
    185 Expected<OwningBinary<ObjectFile>>
    186 ObjectFile::createObjectFile(StringRef ObjectPath) {
    187   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
    188       MemoryBuffer::getFile(ObjectPath);
    189   if (std::error_code EC = FileOrErr.getError())
    190     return errorCodeToError(EC);
    191   std::unique_ptr<MemoryBuffer> Buffer = std::move(FileOrErr.get());
    192 
    193   Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
    194       createObjectFile(Buffer->getMemBufferRef());
    195   if (Error Err = ObjOrErr.takeError())
    196     return std::move(Err);
    197   std::unique_ptr<ObjectFile> Obj = std::move(ObjOrErr.get());
    198 
    199   return OwningBinary<ObjectFile>(std::move(Obj), std::move(Buffer));
    200 }
    201