1 files changed, 496 insertions, 0 deletions
diff --git a/ELF/InputFiles.cpp b/ELF/InputFiles.cpp
new file mode 100644
index 0000000000000..e0827a3ee43d9
--- /dev/null
+++ b/ELF/InputFiles.cpp
@@ -0,0 +1,496 @@
+//===- InputFiles.cpp -----------------------------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InputFiles.h"
+#include "InputSection.h"
+#include "Error.h"
+#include "Symbols.h"
+#include "llvm/ADT/STLExtras.h"
+
+using namespace llvm;
+using namespace llvm::ELF;
+using namespace llvm::object;
+using namespace llvm::sys::fs;
+
+using namespace lld;
+using namespace lld::elf2;
+
+namespace {
+class ECRAII {
+  std::error_code EC;
+
+public:
+  std::error_code &getEC() { return EC; }
+  ~ECRAII() { error(EC); }
+};
+}
+
+template <class ELFT>
+ELFFileBase<ELFT>::ELFFileBase(Kind K, MemoryBufferRef M)
+    : InputFile(K, M), ELFObj(MB.getBuffer(), ECRAII().getEC()) {}
+
+template <class ELFT>
+ELFKind ELFFileBase<ELFT>::getELFKind() {
+  using llvm::support::little;
+  if (ELFT::Is64Bits)
+    return ELFT::TargetEndianness == little ? ELF64LEKind : ELF64BEKind;
+  return ELFT::TargetEndianness == little ? ELF32LEKind : ELF32BEKind;
+}
+
+template <class ELFT>
+typename ELFFileBase<ELFT>::Elf_Sym_Range
+ELFFileBase<ELFT>::getSymbolsHelper(bool Local) {
+  if (!Symtab)
+    return Elf_Sym_Range(nullptr, nullptr);
+  Elf_Sym_Range Syms = ELFObj.symbols(Symtab);
+  uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
+  uint32_t FirstNonLocal = Symtab->sh_info;
+  if (FirstNonLocal > NumSymbols)
+    error("Invalid sh_info in symbol table");
+  if (!Local)
+    return make_range(Syms.begin() + FirstNonLocal, Syms.end());
+  // +1 to skip over dummy symbol.
+  return make_range(Syms.begin() + 1, Syms.begin() + FirstNonLocal);
+}
+
+template <class ELFT>
+uint32_t ELFFileBase<ELFT>::getSectionIndex(const Elf_Sym &Sym) const {
+  uint32_t I = Sym.st_shndx;
+  if (I == ELF::SHN_XINDEX)
+    return this->ELFObj.getExtendedSymbolTableIndex(&Sym, this->Symtab,
+                                                    SymtabSHNDX);
+  if (I >= ELF::SHN_LORESERVE || I == ELF::SHN_ABS)
+    return 0;
+  return I;
+}
+
+template <class ELFT> void ELFFileBase<ELFT>::initStringTable() {
+  if (!Symtab)
+    return;
+  ErrorOr<StringRef> StringTableOrErr = ELFObj.getStringTableForSymtab(*Symtab);
+  error(StringTableOrErr.getError());
+  StringTable = *StringTableOrErr;
+}
+
+template <class ELFT>
+typename ELFFileBase<ELFT>::Elf_Sym_Range
+ELFFileBase<ELFT>::getNonLocalSymbols() {
+  return getSymbolsHelper(false);
+}
+
+template <class ELFT>
+ObjectFile<ELFT>::ObjectFile(MemoryBufferRef M)
+    : ELFFileBase<ELFT>(Base::ObjectKind, M) {}
+
+template <class ELFT>
+typename ObjectFile<ELFT>::Elf_Sym_Range ObjectFile<ELFT>::getLocalSymbols() {
+  return this->getSymbolsHelper(true);
+}
+
+template <class ELFT> uint32_t ObjectFile<ELFT>::getMipsGp0() const {
+  return MipsReginfo ? MipsReginfo->getGp0() : 0;
+}
+
+template <class ELFT>
+const typename ObjectFile<ELFT>::Elf_Sym *
+ObjectFile<ELFT>::getLocalSymbol(uintX_t SymIndex) {
+  uint32_t FirstNonLocal = this->Symtab->sh_info;
+  if (SymIndex >= FirstNonLocal)
+    return nullptr;
+  Elf_Sym_Range Syms = this->ELFObj.symbols(this->Symtab);
+  return Syms.begin() + SymIndex;
+}
+
+template <class ELFT>
+void elf2::ObjectFile<ELFT>::parse(DenseSet<StringRef> &Comdats) {
+  // Read section and symbol tables.
+  initializeSections(Comdats);
+  initializeSymbols();
+}
+
+// Sections with SHT_GROUP and comdat bits define comdat section groups.
+// They are identified and deduplicated by group name. This function
+// returns a group name.
+template <class ELFT>
+StringRef ObjectFile<ELFT>::getShtGroupSignature(const Elf_Shdr &Sec) {
+  const ELFFile<ELFT> &Obj = this->ELFObj;
+  uint32_t SymtabdSectionIndex = Sec.sh_link;
+  ErrorOr<const Elf_Shdr *> SecOrErr = Obj.getSection(SymtabdSectionIndex);
+  error(SecOrErr);
+  const Elf_Shdr *SymtabSec = *SecOrErr;
+  uint32_t SymIndex = Sec.sh_info;
+  const Elf_Sym *Sym = Obj.getSymbol(SymtabSec, SymIndex);
+  ErrorOr<StringRef> StringTableOrErr = Obj.getStringTableForSymtab(*SymtabSec);
+  error(StringTableOrErr);
+  ErrorOr<StringRef> SignatureOrErr = Sym->getName(*StringTableOrErr);
+  error(SignatureOrErr);
+  return *SignatureOrErr;
+}
+
+template <class ELFT>
+ArrayRef<typename ObjectFile<ELFT>::GroupEntryType>
+ObjectFile<ELFT>::getShtGroupEntries(const Elf_Shdr &Sec) {
+  const ELFFile<ELFT> &Obj = this->ELFObj;
+  ErrorOr<ArrayRef<GroupEntryType>> EntriesOrErr =
+      Obj.template getSectionContentsAsArray<GroupEntryType>(&Sec);
+  error(EntriesOrErr.getError());
+  ArrayRef<GroupEntryType> Entries = *EntriesOrErr;
+  if (Entries.empty() || Entries[0] != GRP_COMDAT)
+    error("Unsupported SHT_GROUP format");
+  return Entries.slice(1);
+}
+
+template <class ELFT>
+static bool shouldMerge(const typename ELFFile<ELFT>::Elf_Shdr &Sec) {
+  typedef typename ELFFile<ELFT>::uintX_t uintX_t;
+  uintX_t Flags = Sec.sh_flags;
+  if (!(Flags & SHF_MERGE))
+    return false;
+  if (Flags & SHF_WRITE)
+    error("Writable SHF_MERGE sections are not supported");
+  uintX_t EntSize = Sec.sh_entsize;
+  if (!EntSize || Sec.sh_size % EntSize)
+    error("SHF_MERGE section size must be a multiple of sh_entsize");
+
+  // Don't try to merge if the aligment is larger than the sh_entsize.
+  //
+  // If this is not a SHF_STRINGS, we would need to pad after every entity. It
+  // would be equivalent for the producer of the .o to just set a larger
+  // sh_entsize.
+  //
+  // If this is a SHF_STRINGS, the larger alignment makes sense. Unfortunately
+  // it would complicate tail merging. This doesn't seem that common to
+  // justify the effort.
+  if (Sec.sh_addralign > EntSize)
+    return false;
+
+  return true;
+}
+
+template <class ELFT>
+void elf2::ObjectFile<ELFT>::initializeSections(DenseSet<StringRef> &Comdats) {
+  uint64_t Size = this->ELFObj.getNumSections();
+  Sections.resize(Size);
+  unsigned I = -1;
+  const ELFFile<ELFT> &Obj = this->ELFObj;
+  for (const Elf_Shdr &Sec : Obj.sections()) {
+    ++I;
+    if (Sections[I] == &InputSection<ELFT>::Discarded)
+      continue;
+
+    switch (Sec.sh_type) {
+    case SHT_GROUP:
+      Sections[I] = &InputSection<ELFT>::Discarded;
+      if (Comdats.insert(getShtGroupSignature(Sec)).second)
+        continue;
+      for (GroupEntryType E : getShtGroupEntries(Sec)) {
+        uint32_t SecIndex = E;
+        if (SecIndex >= Size)
+          error("Invalid section index in group");
+        Sections[SecIndex] = &InputSection<ELFT>::Discarded;
+      }
+      break;
+    case SHT_SYMTAB:
+      this->Symtab = &Sec;
+      break;
+    case SHT_SYMTAB_SHNDX: {
+      ErrorOr<ArrayRef<Elf_Word>> ErrorOrTable = Obj.getSHNDXTable(Sec);
+      error(ErrorOrTable);
+      this->SymtabSHNDX = *ErrorOrTable;
+      break;
+    }
+    case SHT_STRTAB:
+    case SHT_NULL:
+      break;
+    case SHT_RELA:
+    case SHT_REL: {
+      uint32_t RelocatedSectionIndex = Sec.sh_info;
+      if (RelocatedSectionIndex >= Size)
+        error("Invalid relocated section index");
+      InputSectionBase<ELFT> *RelocatedSection =
+          Sections[RelocatedSectionIndex];
+      if (!RelocatedSection)
+        error("Unsupported relocation reference");
+      if (auto *S = dyn_cast<InputSection<ELFT>>(RelocatedSection)) {
+        S->RelocSections.push_back(&Sec);
+      } else if (auto *S = dyn_cast<EHInputSection<ELFT>>(RelocatedSection)) {
+        if (S->RelocSection)
+          error("Multiple relocation sections to .eh_frame are not supported");
+        S->RelocSection = &Sec;
+      } else {
+        error("Relocations pointing to SHF_MERGE are not supported");
+      }
+      break;
+    }
+    default:
+      Sections[I] = createInputSection(Sec);
+    }
+  }
+}
+
+template <class ELFT> InputSectionBase<ELFT> *
+elf2::ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
+  ErrorOr<StringRef> NameOrErr = this->ELFObj.getSectionName(&Sec);
+  error(NameOrErr);
+  StringRef Name = *NameOrErr;
+
+  // .note.GNU-stack is a marker section to control the presence of
+  // PT_GNU_STACK segment in outputs. Since the presence of the segment
+  // is controlled only by the command line option (-z execstack) in LLD,
+  // .note.GNU-stack is ignored.
+  if (Name == ".note.GNU-stack")
+    return &InputSection<ELFT>::Discarded;
+
+  // A MIPS object file has a special section that contains register
+  // usage info, which needs to be handled by the linker specially.
+  if (Config->EMachine == EM_MIPS && Name == ".reginfo") {
+    MipsReginfo = new (this->Alloc) MipsReginfoInputSection<ELFT>(this, &Sec);
+    return MipsReginfo;
+  }
+
+  if (Name == ".eh_frame")
+    return new (this->EHAlloc.Allocate()) EHInputSection<ELFT>(this, &Sec);
+  if (shouldMerge<ELFT>(Sec))
+    return new (this->MAlloc.Allocate()) MergeInputSection<ELFT>(this, &Sec);
+  return new (this->Alloc) InputSection<ELFT>(this, &Sec);
+}
+
+template <class ELFT> void elf2::ObjectFile<ELFT>::initializeSymbols() {
+  this->initStringTable();
+  Elf_Sym_Range Syms = this->getNonLocalSymbols();
+  uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
+  this->SymbolBodies.reserve(NumSymbols);
+  for (const Elf_Sym &Sym : Syms)
+    this->SymbolBodies.push_back(createSymbolBody(this->StringTable, &Sym));
+}
+
+template <class ELFT>
+InputSectionBase<ELFT> *
+elf2::ObjectFile<ELFT>::getSection(const Elf_Sym &Sym) const {
+  uint32_t Index = this->getSectionIndex(Sym);
+  if (Index == 0)
+    return nullptr;
+  if (Index >= Sections.size() || !Sections[Index])
+    error("Invalid section index");
+  return Sections[Index];
+}
+
+template <class ELFT>
+SymbolBody *elf2::ObjectFile<ELFT>::createSymbolBody(StringRef StringTable,
+                                                     const Elf_Sym *Sym) {
+  ErrorOr<StringRef> NameOrErr = Sym->getName(StringTable);
+  error(NameOrErr.getError());
+  StringRef Name = *NameOrErr;
+
+  switch (Sym->st_shndx) {
+  case SHN_UNDEF:
+    return new (this->Alloc) UndefinedElf<ELFT>(Name, *Sym);
+  case SHN_COMMON:
+    return new (this->Alloc) DefinedCommon(
+        Name, Sym->st_size, Sym->st_value,
+        Sym->getBinding() == llvm::ELF::STB_WEAK, Sym->getVisibility());
+  }
+
+  switch (Sym->getBinding()) {
+  default:
+    error("unexpected binding");
+  case STB_GLOBAL:
+  case STB_WEAK:
+  case STB_GNU_UNIQUE: {
+    InputSectionBase<ELFT> *Sec = getSection(*Sym);
+    if (Sec == &InputSection<ELFT>::Discarded)
+      return new (this->Alloc) UndefinedElf<ELFT>(Name, *Sym);
+    return new (this->Alloc) DefinedRegular<ELFT>(Name, *Sym, Sec);
+  }
+  }
+}
+
+static std::unique_ptr<Archive> openArchive(MemoryBufferRef MB) {
+  ErrorOr<std::unique_ptr<Archive>> ArchiveOrErr = Archive::create(MB);
+  error(ArchiveOrErr, "Failed to parse archive");
+  return std::move(*ArchiveOrErr);
+}
+
+void ArchiveFile::parse() {
+  File = openArchive(MB);
+
+  // Allocate a buffer for Lazy objects.
+  size_t NumSyms = File->getNumberOfSymbols();
+  LazySymbols.reserve(NumSyms);
+
+  // Read the symbol table to construct Lazy objects.
+  for (const Archive::Symbol &Sym : File->symbols())
+    LazySymbols.emplace_back(this, Sym);
+}
+
+// Returns a buffer pointing to a member file containing a given symbol.
+MemoryBufferRef ArchiveFile::getMember(const Archive::Symbol *Sym) {
+  ErrorOr<Archive::Child> COrErr = Sym->getMember();
+  error(COrErr, "Could not get the member for symbol " + Sym->getName());
+  const Archive::Child &C = *COrErr;
+
+  if (!Seen.insert(C.getChildOffset()).second)
+    return MemoryBufferRef();
+
+  ErrorOr<MemoryBufferRef> RefOrErr = C.getMemoryBufferRef();
+  if (!RefOrErr)
+    error(RefOrErr, "Could not get the buffer for the member defining symbol " +
+          Sym->getName());
+  return *RefOrErr;
+}
+
+std::vector<MemoryBufferRef> ArchiveFile::getMembers() {
+  File = openArchive(MB);
+
+  std::vector<MemoryBufferRef> Result;
+  for (auto &ChildOrErr : File->children()) {
+    error(ChildOrErr,
+          "Could not get the child of the archive " + File->getFileName());
+    const Archive::Child Child(*ChildOrErr);
+    ErrorOr<MemoryBufferRef> MbOrErr = Child.getMemoryBufferRef();
+    if (!MbOrErr)
+      error(MbOrErr, "Could not get the buffer for a child of the archive " +
+            File->getFileName());
+    Result.push_back(MbOrErr.get());
+  }
+  return Result;
+}
+
+template <class ELFT>
+SharedFile<ELFT>::SharedFile(MemoryBufferRef M)
+    : ELFFileBase<ELFT>(Base::SharedKind, M) {
+  AsNeeded = Config->AsNeeded;
+}
+
+template <class ELFT>
+const typename ELFFile<ELFT>::Elf_Shdr *
+SharedFile<ELFT>::getSection(const Elf_Sym &Sym) const {
+  uint32_t Index = this->getSectionIndex(Sym);
+  if (Index == 0)
+    return nullptr;
+  ErrorOr<const Elf_Shdr *> Ret = this->ELFObj.getSection(Index);
+  error(Ret);
+  return *Ret;
+}
+
+template <class ELFT> void SharedFile<ELFT>::parseSoName() {
+  typedef typename ELFFile<ELFT>::Elf_Dyn Elf_Dyn;
+  typedef typename ELFFile<ELFT>::uintX_t uintX_t;
+  const Elf_Shdr *DynamicSec = nullptr;
+
+  const ELFFile<ELFT> Obj = this->ELFObj;
+  for (const Elf_Shdr &Sec : Obj.sections()) {
+    switch (Sec.sh_type) {
+    default:
+      continue;
+    case SHT_DYNSYM:
+      this->Symtab = &Sec;
+      break;
+    case SHT_DYNAMIC:
+      DynamicSec = &Sec;
+      break;
+    case SHT_SYMTAB_SHNDX: {
+      ErrorOr<ArrayRef<Elf_Word>> ErrorOrTable = Obj.getSHNDXTable(Sec);
+      error(ErrorOrTable);
+      this->SymtabSHNDX = *ErrorOrTable;
+      break;
+    }
+    }
+  }
+
+  this->initStringTable();
+  this->SoName = this->getName();
+
+  if (!DynamicSec)
+    return;
+  auto *Begin =
+      reinterpret_cast<const Elf_Dyn *>(Obj.base() + DynamicSec->sh_offset);
+  const Elf_Dyn *End = Begin + DynamicSec->sh_size / sizeof(Elf_Dyn);
+
+  for (const Elf_Dyn &Dyn : make_range(Begin, End)) {
+    if (Dyn.d_tag == DT_SONAME) {
+      uintX_t Val = Dyn.getVal();
+      if (Val >= this->StringTable.size())
+        error("Invalid DT_SONAME entry");
+      this->SoName = StringRef(this->StringTable.data() + Val);
+      return;
+    }
+  }
+}
+
+template <class ELFT> void SharedFile<ELFT>::parse() {
+  Elf_Sym_Range Syms = this->getNonLocalSymbols();
+  uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
+  SymbolBodies.reserve(NumSymbols);
+  for (const Elf_Sym &Sym : Syms) {
+    ErrorOr<StringRef> NameOrErr = Sym.getName(this->StringTable);
+    error(NameOrErr.getError());
+    StringRef Name = *NameOrErr;
+
+    if (Sym.isUndefined())
+      Undefs.push_back(Name);
+    else
+      SymbolBodies.emplace_back(this, Name, Sym);
+  }
+}
+
+template <typename T>
+static std::unique_ptr<InputFile> createELFFileAux(MemoryBufferRef MB) {
+  std::unique_ptr<T> Ret = llvm::make_unique<T>(MB);
+
+  if (!Config->FirstElf)
+    Config->FirstElf = Ret.get();
+
+  if (Config->EKind == ELFNoneKind) {
+    Config->EKind = Ret->getELFKind();
+    Config->EMachine = Ret->getEMachine();
+  }
+
+  return std::move(Ret);
+}
+
+template <template <class> class T>
+std::unique_ptr<InputFile> lld::elf2::createELFFile(MemoryBufferRef MB) {
+  std::pair<unsigned char, unsigned char> Type = getElfArchType(MB.getBuffer());
+  if (Type.second != ELF::ELFDATA2LSB && Type.second != ELF::ELFDATA2MSB)
+    error("Invalid data encoding: " + MB.getBufferIdentifier());
+
+  if (Type.first == ELF::ELFCLASS32) {
+    if (Type.second == ELF::ELFDATA2LSB)
+      return createELFFileAux<T<ELF32LE>>(MB);
+    return createELFFileAux<T<ELF32BE>>(MB);
+  }
+  if (Type.first == ELF::ELFCLASS64) {
+    if (Type.second == ELF::ELFDATA2LSB)
+      return createELFFileAux<T<ELF64LE>>(MB);
+    return createELFFileAux<T<ELF64BE>>(MB);
+  }
+  error("Invalid file class: " + MB.getBufferIdentifier());
+}
+
+template class elf2::ELFFileBase<ELF32LE>;
+template class elf2::ELFFileBase<ELF32BE>;
+template class elf2::ELFFileBase<ELF64LE>;
+template class elf2::ELFFileBase<ELF64BE>;
+
+template class elf2::ObjectFile<ELF32LE>;
+template class elf2::ObjectFile<ELF32BE>;
+template class elf2::ObjectFile<ELF64LE>;
+template class elf2::ObjectFile<ELF64BE>;
+
+template class elf2::SharedFile<ELF32LE>;
+template class elf2::SharedFile<ELF32BE>;
+template class elf2::SharedFile<ELF64LE>;
+template class elf2::SharedFile<ELF64BE>;
+
+template std::unique_ptr<InputFile>
+elf2::createELFFile<ObjectFile>(MemoryBufferRef);
+
+template std::unique_ptr<InputFile>
+elf2::createELFFile<SharedFile>(MemoryBufferRef);