text: //===-- ELFDump.cpp - ELF-specific dumper -----------------------*- 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
  //
  //===----------------------------------------------------------------------===//
  ///
  /// \file
  /// This file implements the ELF-specific dumper for llvm-objdump.
  ///
  //===----------------------------------------------------------------------===//
  
  #include "llvm-objdump.h"
  #include "llvm/Demangle/Demangle.h"
  #include "llvm/Object/ELFObjectFile.h"
  #include "llvm/Support/Format.h"
  #include "llvm/Support/MathExtras.h"
  #include "llvm/Support/raw_ostream.h"
  
  using namespace llvm::object;
  
  namespace llvm {
  template <class ELFT>
  static Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> *Elf) {
    auto DynamicEntriesOrError = Elf->dynamicEntries();
    if (!DynamicEntriesOrError)
      return DynamicEntriesOrError.takeError();
  
    for (const typename ELFT::Dyn &Dyn : *DynamicEntriesOrError) {
      if (Dyn.d_tag == ELF::DT_STRTAB) {
        auto MappedAddrOrError = Elf->toMappedAddr(Dyn.getPtr());
        if (!MappedAddrOrError)
          consumeError(MappedAddrOrError.takeError());
        return StringRef(reinterpret_cast<const char *>(*MappedAddrOrError));
      }
    }
  
    // If the dynamic segment is not present, we fall back on the sections.
    auto SectionsOrError = Elf->sections();
    if (!SectionsOrError)
      return SectionsOrError.takeError();
  
    for (const typename ELFT::Shdr &Sec : *SectionsOrError) {
      if (Sec.sh_type == ELF::SHT_DYNSYM)
        return Elf->getStringTableForSymtab(Sec);
    }
  
    return createError("dynamic string table not found");
  }
  
  template <class ELFT>
  static Error getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
                                        const RelocationRef &RelRef,
                                        SmallVectorImpl<char> &Result) {
    const ELFFile<ELFT> &EF = *Obj->getELFFile();
    DataRefImpl Rel = RelRef.getRawDataRefImpl();
    auto SecOrErr = EF.getSection(Rel.d.a);
    if (!SecOrErr)
      return SecOrErr.takeError();
  
    int64_t Addend = 0;
    // If there is no Symbol associated with the relocation, we set the undef
    // boolean value to 'true'. This will prevent us from calling functions that
    // requires the relocation to be associated with a symbol.
    //
    // In SHT_REL case we would need to read the addend from section data.
    // GNU objdump does not do that and we just follow for simplicity atm.
    bool Undef = false;
    if ((*SecOrErr)->sh_type == ELF::SHT_RELA) {
      const typename ELFT::Rela *ERela = Obj->getRela(Rel);
      Addend = ERela->r_addend;
      Undef = ERela->getSymbol(false) == 0;
    } else if ((*SecOrErr)->sh_type != ELF::SHT_REL) {
      return make_error<BinaryError>();
    }
  
    // Default scheme is to print Target, as well as "+ <addend>" for nonzero
    // addend. Should be acceptable for all normal purposes.
    std::string FmtBuf;
    raw_string_ostream Fmt(FmtBuf);
  
    if (!Undef) {
      symbol_iterator SI = RelRef.getSymbol();
      const typename ELFT::Sym *Sym = Obj->getSymbol(SI->getRawDataRefImpl());
      if (Sym->getType() == ELF::STT_SECTION) {
        Expected<section_iterator> SymSI = SI->getSection();
        if (!SymSI)
          return SymSI.takeError();
        const typename ELFT::Shdr *SymSec =
            Obj->getSection((*SymSI)->getRawDataRefImpl());
        auto SecName = EF.getSectionName(SymSec);
        if (!SecName)
          return SecName.takeError();
        Fmt << *SecName;
      } else {
        Expected<StringRef> SymName = SI->getName();
        if (!SymName)
          return SymName.takeError();
        if (Demangle)
          Fmt << demangle(std::string(*SymName));
        else
          Fmt << *SymName;
      }
    } else {
      Fmt << "*ABS*";
    }
    if (Addend != 0) {
        Fmt << (Addend < 0
            ? "-"
            : "+") << format("0x%" PRIx64,
                            (Addend < 0 ? -(uint64_t)Addend : (uint64_t)Addend));
    }
    Fmt.flush();
    Result.append(FmtBuf.begin(), FmtBuf.end());
    return Error::success();
  }
  
  Error getELFRelocationValueString(const ELFObjectFileBase *Obj,
                                    const RelocationRef &Rel,
                                    SmallVectorImpl<char> &Result) {
    if (auto *ELF32LE = dyn_cast<ELF32LEObjectFile>(Obj))
      return getRelocationValueString(ELF32LE, Rel, Result);
    if (auto *ELF64LE = dyn_cast<ELF64LEObjectFile>(Obj))
      return getRelocationValueString(ELF64LE, Rel, Result);
    if (auto *ELF32BE = dyn_cast<ELF32BEObjectFile>(Obj))
      return getRelocationValueString(ELF32BE, Rel, Result);
    auto *ELF64BE = cast<ELF64BEObjectFile>(Obj);
    return getRelocationValueString(ELF64BE, Rel, Result);
  }
  
  template <class ELFT>
  static uint64_t getSectionLMA(const ELFFile<ELFT> *Obj,
                                const object::ELFSectionRef &Sec) {
    auto PhdrRangeOrErr = Obj->program_headers();
    if (!PhdrRangeOrErr)
      report_fatal_error(toString(PhdrRangeOrErr.takeError()));
  
    // Search for a PT_LOAD segment containing the requested section. Use this
    // segment's p_addr to calculate the section's LMA.
    for (const typename ELFT::Phdr &Phdr : *PhdrRangeOrErr)
      if ((Phdr.p_type == ELF::PT_LOAD) && (Phdr.p_vaddr <= Sec.getAddress()) &&
          (Phdr.p_vaddr + Phdr.p_memsz > Sec.getAddress()))
        return Sec.getAddress() - Phdr.p_vaddr + Phdr.p_paddr;
  
    // Return section's VMA if it isn't in a PT_LOAD segment.
    return Sec.getAddress();
  }
  
  uint64_t getELFSectionLMA(const object::ELFSectionRef &Sec) {
    if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Sec.getObject()))
      return getSectionLMA(ELFObj->getELFFile(), Sec);
    else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Sec.getObject()))
      return getSectionLMA(ELFObj->getELFFile(), Sec);
    else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Sec.getObject()))
      return getSectionLMA(ELFObj->getELFFile(), Sec);
    const auto *ELFObj = cast<ELF64BEObjectFile>(Sec.getObject());
    return getSectionLMA(ELFObj->getELFFile(), Sec);
  }
  
  template <class ELFT>
  void printDynamicSection(const ELFFile<ELFT> *Elf, StringRef Filename) {
    ArrayRef<typename ELFT::Dyn> DynamicEntries =
        unwrapOrError(Elf->dynamicEntries(), Filename);
  
    // Find the maximum tag name length to format the value column properly.
    size_t MaxLen = 0;
    for (const typename ELFT::Dyn &Dyn : DynamicEntries)
      MaxLen = std::max(MaxLen, Elf->getDynamicTagAsString(Dyn.d_tag).size());
    std::string TagFmt = "  %-" + std::to_string(MaxLen) + "s ";
  
    outs() << "Dynamic Section:\n";
    for (const typename ELFT::Dyn &Dyn : DynamicEntries) {
      if (Dyn.d_tag == ELF::DT_NULL)
        continue;
  
      std::string Str = Elf->getDynamicTagAsString(Dyn.d_tag);
      outs() << format(TagFmt.c_str(), Str.c_str());
  
      const char *Fmt =
          ELFT::Is64Bits ? "0x%016" PRIx64 "\n" : "0x%08" PRIx64 "\n";
      if (Dyn.d_tag == ELF::DT_NEEDED || Dyn.d_tag == ELF::DT_RPATH ||
          Dyn.d_tag == ELF::DT_RUNPATH || Dyn.d_tag == ELF::DT_SONAME ||
          Dyn.d_tag == ELF::DT_AUXILIARY || Dyn.d_tag == ELF::DT_FILTER) {
        Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf);
        if (StrTabOrErr) {
          const char *Data = StrTabOrErr.get().data();
          outs() << (Data + Dyn.d_un.d_val) << "\n";
          continue;
        }
        reportWarning(toString(StrTabOrErr.takeError()), Filename);
        consumeError(StrTabOrErr.takeError());
      }
      outs() << format(Fmt, (uint64_t)Dyn.d_un.d_val);
    }
  }
  
  template <class ELFT> void printProgramHeaders(const ELFFile<ELFT> *o) {
    outs() << "Program Header:\n";
    auto ProgramHeaderOrError = o->program_headers();
    if (!ProgramHeaderOrError)
      report_fatal_error(toString(ProgramHeaderOrError.takeError()));
    for (const typename ELFT::Phdr &Phdr : *ProgramHeaderOrError) {
      switch (Phdr.p_type) {
      case ELF::PT_DYNAMIC:
        outs() << " DYNAMIC ";
        break;
      case ELF::PT_GNU_EH_FRAME:
        outs() << "EH_FRAME ";
        break;
      case ELF::PT_GNU_RELRO:
        outs() << "   RELRO ";
        break;
      case ELF::PT_GNU_PROPERTY:
        outs() << "   PROPERTY ";
        break;
      case ELF::PT_GNU_STACK:
        outs() << "   STACK ";
        break;
      case ELF::PT_INTERP:
        outs() << "  INTERP ";
        break;
      case ELF::PT_LOAD:
        outs() << "    LOAD ";
        break;
      case ELF::PT_NOTE:
        outs() << "    NOTE ";
        break;
      case ELF::PT_OPENBSD_BOOTDATA:
        outs() << "    OPENBSD_BOOTDATA ";
        break;
      case ELF::PT_OPENBSD_RANDOMIZE:
        outs() << "    OPENBSD_RANDOMIZE ";
        break;
      case ELF::PT_OPENBSD_WXNEEDED:
        outs() << "    OPENBSD_WXNEEDED ";
        break;
      case ELF::PT_PHDR:
        outs() << "    PHDR ";
        break;
      case ELF::PT_TLS:
        outs() << "    TLS ";
        break;
      default:
        outs() << " UNKNOWN ";
      }
  
      const char *Fmt = ELFT::Is64Bits ? "0x%016" PRIx64 " " : "0x%08" PRIx64 " ";
  
      outs() << "off    " << format(Fmt, (uint64_t)Phdr.p_offset) << "vaddr "
             << format(Fmt, (uint64_t)Phdr.p_vaddr) << "paddr "
             << format(Fmt, (uint64_t)Phdr.p_paddr)
             << format("align 2**%u\n",
                       countTrailingZeros<uint64_t>(Phdr.p_align))
             << "         filesz " << format(Fmt, (uint64_t)Phdr.p_filesz)
             << "memsz " << format(Fmt, (uint64_t)Phdr.p_memsz) << "flags "
             << ((Phdr.p_flags & ELF::PF_R) ? "r" : "-")
             << ((Phdr.p_flags & ELF::PF_W) ? "w" : "-")
             << ((Phdr.p_flags & ELF::PF_X) ? "x" : "-") << "\n";
    }
    outs() << "\n";
  }
  
  template <class ELFT>
  void printSymbolVersionDependency(ArrayRef<uint8_t> Contents,
                                    StringRef StrTab) {
    outs() << "Version References:\n";
  
    const uint8_t *Buf = Contents.data();
    while (Buf) {
      auto *Verneed = reinterpret_cast<const typename ELFT::Verneed *>(Buf);
      outs() << "  required from "
             << StringRef(StrTab.drop_front(Verneed->vn_file).data()) << ":\n";
  
      const uint8_t *BufAux = Buf + Verneed->vn_aux;
      while (BufAux) {
        auto *Vernaux = reinterpret_cast<const typename ELFT::Vernaux *>(BufAux);
        outs() << "    "
               << format("0x%08" PRIx32 " ", (uint32_t)Vernaux->vna_hash)
               << format("0x%02" PRIx16 " ", (uint16_t)Vernaux->vna_flags)
               << format("%02" PRIu16 " ", (uint16_t)Vernaux->vna_other)
               << StringRef(StrTab.drop_front(Vernaux->vna_name).data()) << '\n';
        BufAux = Vernaux->vna_next ? BufAux + Vernaux->vna_next : nullptr;
      }
      Buf = Verneed->vn_next ? Buf + Verneed->vn_next : nullptr;
    }
  }
  
  template <class ELFT>
  void printSymbolVersionDefinition(const typename ELFT::Shdr &Shdr,
                                    ArrayRef<uint8_t> Contents,
                                    StringRef StrTab) {
    outs() << "Version definitions:\n";
  
    const uint8_t *Buf = Contents.data();
    uint32_t VerdefIndex = 1;
    // sh_info contains the number of entries in the SHT_GNU_verdef section. To
    // make the index column have consistent width, we should insert blank spaces
    // according to sh_info.
    uint16_t VerdefIndexWidth = std::to_string(Shdr.sh_info).size();
    while (Buf) {
      auto *Verdef = reinterpret_cast<const typename ELFT::Verdef *>(Buf);
      outs() << format_decimal(VerdefIndex++, VerdefIndexWidth) << " "
             << format("0x%02" PRIx16 " ", (uint16_t)Verdef->vd_flags)
             << format("0x%08" PRIx32 " ", (uint32_t)Verdef->vd_hash);
  
      const uint8_t *BufAux = Buf + Verdef->vd_aux;
      uint16_t VerdauxIndex = 0;
      while (BufAux) {
        auto *Verdaux = reinterpret_cast<const typename ELFT::Verdaux *>(BufAux);
        if (VerdauxIndex)
          outs() << std::string(VerdefIndexWidth + 17, ' ');
        outs() << StringRef(StrTab.drop_front(Verdaux->vda_name).data()) << '\n';
        BufAux = Verdaux->vda_next ? BufAux + Verdaux->vda_next : nullptr;
        ++VerdauxIndex;
      }
      Buf = Verdef->vd_next ? Buf + Verdef->vd_next : nullptr;
    }
  }
  
  template <class ELFT>
  void printSymbolVersionInfo(const ELFFile<ELFT> *Elf, StringRef FileName) {
    ArrayRef<typename ELFT::Shdr> Sections =
        unwrapOrError(Elf->sections(), FileName);
    for (const typename ELFT::Shdr &Shdr : Sections) {
      if (Shdr.sh_type != ELF::SHT_GNU_verneed &&
          Shdr.sh_type != ELF::SHT_GNU_verdef)
        continue;
  
      ArrayRef<uint8_t> Contents =
          unwrapOrError(Elf->getSectionContents(&Shdr), FileName);
      const typename ELFT::Shdr *StrTabSec =
          unwrapOrError(Elf->getSection(Shdr.sh_link), FileName);
      StringRef StrTab = unwrapOrError(Elf->getStringTable(StrTabSec), FileName);
  
      if (Shdr.sh_type == ELF::SHT_GNU_verneed)
        printSymbolVersionDependency<ELFT>(Contents, StrTab);
      else
        printSymbolVersionDefinition<ELFT>(Shdr, Contents, StrTab);
    }
  }
  
  void printELFFileHeader(const object::ObjectFile *Obj) {
    if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
      printProgramHeaders(ELFObj->getELFFile());
    else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
      printProgramHeaders(ELFObj->getELFFile());
    else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
      printProgramHeaders(ELFObj->getELFFile());
    else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
      printProgramHeaders(ELFObj->getELFFile());
  }
  
  void printELFDynamicSection(const object::ObjectFile *Obj) {
    if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
      printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
    else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
      printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
    else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
      printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
    else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
      printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
  }
  
  void printELFSymbolVersionInfo(const object::ObjectFile *Obj) {
    if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
      printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
    else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
      printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
    else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
      printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
    else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
      printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
  }
  } // namespace llvm
  