ELF: Do not treat errors in InputFiles class as fatal errors.

[ruiu]

Summary

This file is not as easy to handle errors as the driver or the
symbol table because of the nature of file IO. However, I think
this patch is not as horrible as I expected; I'm fairly satisfied
with this change. If we find an error, we call error() to record
the error, and return a zero value. Zero value is an empty
vector for the vector, nullptr for a pointer, or an empty string
for the StringRef. Callers gracefully handle such values.

In some cases, we don't have good zero values. I changed the
type of such functions so that they return a boolean value.

All changes are mechanical and should not change the existing
behavior.

[• rafael]

First thing: testcase? :-)

[• rafael]

ELF/InputFiles.cpp

213

It looks like most of this patch is converting uses of fatal that can only be reached with broken files.

I don't see the point of supporting some broken files but not others, and I don't think this will scale to supporting all.

ELF/Driver.cpp

void LinkerDriver::addFile(StringRef Path) {
 
   switch (identify_magic(MBRef.getBuffer())) {
   case file_magic::unknown:
     readLinkerScript(&Alloc, MBRef);
     return;
   case file_magic::archive:
     if (WholeArchive) {
       for (MemoryBufferRef MB : getArchiveMembers(MBRef))
-        Files.push_back(createObjectFile(MB));
+        if (std::unique_ptr<InputFile> F = createObjectFile(MB))
+          Files.push_back(std::move(F));
       return;
     }
     Files.push_back(make_unique<ArchiveFile>(MBRef));
     return;
   case file_magic::elf_shared_object:
-    Files.push_back(createSharedFile(MBRef));
+    if (std::unique_ptr<InputFile> F = createSharedFile(MBRef))
+      Files.push_back(std::move(F));
     return;
   default:
-    Files.push_back(createObjectFile(MBRef));
+    if (std::unique_ptr<InputFile> F = createObjectFile(MBRef))
+      Files.push_back(std::move(F));
   }
 }
 
 // Add a given library by searching it from input search paths.
 void LinkerDriver::addLibrary(StringRef Name) {
   StringRef Path = searchLibrary(Name);
   if (Path.empty())
     error("Unable to find library -l" + Name);

ELF/InputFiles.h

public:
 
   uint32_t getSectionIndex(const Elf_Sym &Sym) const;
 
 protected:
   llvm::object::ELFFile<ELFT> ELFObj;
   const Elf_Shdr *Symtab = nullptr;
   ArrayRef<Elf_Word> SymtabSHNDX;
   StringRef StringTable;
-  void initStringTable();
+  bool initStringTable();
   Elf_Sym_Range getNonLocalSymbols();
   Elf_Sym_Range getSymbolsHelper(bool);
 };
 
 // .o file.
 template <class ELFT> class ObjectFile : public ELFFileBase<ELFT> {
   typedef ELFFileBase<ELFT> Base;
   typedef typename llvm::object::ELFFile<ELFT>::Elf_Sym Elf_Sym;
   typedef typename llvm::object::ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
   typedef typename llvm::object::ELFFile<ELFT>::Elf_Sym_Range Elf_Sym_Range;
   typedef typename llvm::object::ELFFile<ELFT>::Elf_Word Elf_Word;
   typedef typename llvm::object::ELFFile<ELFT>::uintX_t uintX_t;
 
   // uint32 in ELFT's byte order
   typedef llvm::support::detail::packed_endian_specific_integral<
       uint32_t, ELFT::TargetEndianness, 2>
       uint32_X;
 
-  StringRef getShtGroupSignature(const Elf_Shdr &Sec);
+  bool getShtGroupSignature(const Elf_Shdr &Sec, StringRef &Result);
   ArrayRef<uint32_X> getShtGroupEntries(const Elf_Shdr &Sec);
 
 public:
   static bool classof(const InputFile *F) {
     return F->kind() == Base::ObjectKind;
   }
 
   ArrayRef<SymbolBody *> getSymbols() { return SymbolBodies; }
 
   explicit ObjectFile(MemoryBufferRef M);
-  void parse(llvm::DenseSet<StringRef> &ComdatGroups);
+  bool parse(llvm::DenseSet<StringRef> &ComdatGroups);
 
   ArrayRef<InputSectionBase<ELFT> *> getSections() const { return Sections; }
   InputSectionBase<ELFT> *getSection(const Elf_Sym &Sym) const;
 
   SymbolBody *getSymbolBody(uint32_t SymbolIndex) const {
     uint32_t FirstNonLocal = this->Symtab->sh_info;
     if (SymbolIndex < FirstNonLocal)
       return nullptr;
     return SymbolBodies[SymbolIndex - FirstNonLocal];
   }
 
   Elf_Sym_Range getLocalSymbols();
   const Elf_Sym *getLocalSymbol(uintX_t SymIndex);
 
   const Elf_Shdr *getSymbolTable() const { return this->Symtab; };
 
   // Get MIPS GP0 value defined by this file. This value represents the gp value
   // used to create the relocatable object and required to support
   // R_MIPS_GPREL16 / R_MIPS_GPREL32 relocations.
   uint32_t getMipsGp0() const;
 
   std::vector<const Elf_Sym *> KeptLocalSyms;
 
 private:
-  void initializeSections(llvm::DenseSet<StringRef> &ComdatGroups);
-  void initializeSymbols();
-  InputSectionBase<ELFT> *createInputSection(const Elf_Shdr &Sec);
+  bool initializeSections(llvm::DenseSet<StringRef> &ComdatGroups);
+  bool initializeSymbols();
+  InputSectionBase<ELFT> *createInputSection(const Elf_Shdr &Sec, StringRef Name);
 
   SymbolBody *createSymbolBody(const Elf_Sym *Sym);
 
   // List of all sections defined by this file.
   std::vector<InputSectionBase<ELFT> *> Sections;
 
   // List of all symbols referenced or defined by this file.
   std::vector<SymbolBody *> SymbolBodies;
 
   // MIPS .reginfo section defined by this file.
   MipsReginfoInputSection<ELFT> *MipsReginfo = nullptr;
 
   llvm::BumpPtrAllocator Alloc;
   llvm::SpecificBumpPtrAllocator<MergeInputSection<ELFT>> MAlloc;
   llvm::SpecificBumpPtrAllocator<EHInputSection<ELFT>> EHAlloc;
 };
 
 class ArchiveFile : public InputFile {
 public:
   explicit ArchiveFile(MemoryBufferRef M) : InputFile(ArchiveKind, M) {}
   static bool classof(const InputFile *F) { return F->kind() == ArchiveKind; }
-  void parse();
+  bool parse();
 
   // Returns a memory buffer for a given symbol. An empty memory buffer
   // is returned if we have already returned the same memory buffer.
   // (So that we don't instantiate same members more than once.)
   MemoryBufferRef getMember(const Archive::Symbol *Sym);
 
   llvm::MutableArrayRef<Lazy> getLazySymbols() { return LazySymbols; }
 
public:
   llvm::ArrayRef<StringRef> getUndefinedSymbols() { return Undefs; }
 
   static bool classof(const InputFile *F) {
     return F->kind() == Base::SharedKind;
   }
 
   explicit SharedFile(MemoryBufferRef M);
 
-  void parseSoName();
-  void parseRest();
+  bool parseSoName();
+  bool parseRest();
 
   // Used for --as-needed
   bool AsNeeded = false;
   bool IsUsed = false;
   bool isNeeded() const { return !AsNeeded || IsUsed; }
 };
 
 std::unique_ptr<InputFile> createObjectFile(MemoryBufferRef MB);
 std::unique_ptr<InputFile> createSharedFile(MemoryBufferRef MB);
 
 } // namespace elf2
 } // namespace lld
 
 #endif

ELF/InputFiles.cpp

 using namespace lld::elf2;
 
 namespace {
 class ECRAII {
   std::error_code EC;
 
 public:
   std::error_code &getEC() { return EC; }
-  ~ECRAII() { fatal(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() {
   if (ELFT::TargetEndianness == support::little)
     return ELFT::Is64Bits ? ELF64LEKind : ELF32LEKind;
   return ELFT::Is64Bits ? ELF64BEKind : 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)
-    fatal("Invalid sh_info in symbol table");
+  if (FirstNonLocal > NumSymbols) {
+    error("Invalid sh_info in symbol table");
+    return Elf_Sym_Range(nullptr, nullptr);
+  }
   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 ELFObj.getExtendedSymbolTableIndex(&Sym, Symtab, SymtabSHNDX);
   if (I >= ELF::SHN_LORESERVE || I == ELF::SHN_ABS)
     return 0;
   return I;
 }
 
-template <class ELFT> void ELFFileBase<ELFT>::initStringTable() {
+template <class ELFT> bool ELFFileBase<ELFT>::initStringTable() {
   if (!Symtab)
-    return;
+    return true;
   ErrorOr<StringRef> StringTableOrErr = ELFObj.getStringTableForSymtab(*Symtab);
-  fatal(StringTableOrErr);
+  if (error(StringTableOrErr, "corrupted file"))
+    return false;
   StringTable = *StringTableOrErr;
+  return true;
 }
 
 template <class ELFT>
 typename ELFFileBase<ELFT>::Elf_Sym_Range
 ELFFileBase<ELFT>::getNonLocalSymbols() {
   return getSymbolsHelper(false);
 }
 
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 ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
+bool ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
   // Read section and symbol tables.
-  initializeSections(ComdatGroups);
-  initializeSymbols();
+  if (!initializeSections(ComdatGroups))
+    return false;
+  if (!initializeSymbols())
+    return false;
+  return true;
 }
 
 // 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) {
+bool ObjectFile<ELFT>::getShtGroupSignature(const Elf_Shdr &Sec, StringRef &Result) {
   const ELFFile<ELFT> &Obj = this->ELFObj;
   uint32_t SymtabdSectionIndex = Sec.sh_link;
   ErrorOr<const Elf_Shdr *> SecOrErr = Obj.getSection(SymtabdSectionIndex);
-  fatal(SecOrErr);
+  if (error(SecOrErr, "corrupted file"))
+    return false;
   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);
-  fatal(StringTableOrErr);
+  if (error(StringTableOrErr, "corrupted file"))
+    return false;
   ErrorOr<StringRef> SignatureOrErr = Sym->getName(*StringTableOrErr);
-  fatal(SignatureOrErr);
-  return *SignatureOrErr;
+  if (error(SignatureOrErr, "corrupted file"))
+    return false;
+  Result = *SignatureOrErr;
+  return true;
 }
 
 template <class ELFT>
 ArrayRef<typename ObjectFile<ELFT>::uint32_X>
 ObjectFile<ELFT>::getShtGroupEntries(const Elf_Shdr &Sec) {
   const ELFFile<ELFT> &Obj = this->ELFObj;
   ErrorOr<ArrayRef<uint32_X>> EntriesOrErr =
       Obj.template getSectionContentsAsArray<uint32_X>(&Sec);
-  fatal(EntriesOrErr);
+  if (error(EntriesOrErr, "corrupted file"))
+    return {};
   ArrayRef<uint32_X> Entries = *EntriesOrErr;
-  if (Entries.empty() || Entries[0] != GRP_COMDAT)
-    fatal("Unsupported SHT_GROUP format");
+  if (Entries.empty() || Entries[0] != GRP_COMDAT) {
+    error("Unsupported SHT_GROUP format");
+    return {};
+  }
   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)
-    fatal("Writable SHF_MERGE sections are not supported");
+  if (Flags & SHF_WRITE) {
+    error("Writable SHF_MERGE sections are not supported");
+    return false;
+  }
   uintX_t EntSize = Sec.sh_entsize;
-  if (!EntSize || Sec.sh_size % EntSize)
-    fatal("SHF_MERGE section size must be a multiple of sh_entsize");
+  if (!EntSize || Sec.sh_size % EntSize) {
+    error("SHF_MERGE section size must be a multiple of sh_entsize");
+    return false;
+  }
 
   // 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 ObjectFile<ELFT>::initializeSections(DenseSet<StringRef> &ComdatGroups) {
+bool ObjectFile<ELFT>::initializeSections(DenseSet<StringRef> &ComdatGroups) {
   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:
+    case SHT_GROUP: {
       Sections[I] = &InputSection<ELFT>::Discarded;
-      if (ComdatGroups.insert(getShtGroupSignature(Sec)).second)
+      StringRef Sig;
+      if (!getShtGroupSignature(Sec, Sig))
+        return false;
+      if (ComdatGroups.insert(Sig).second)
         continue;
       for (uint32_t SecIndex : getShtGroupEntries(Sec)) {
-        if (SecIndex >= Size)
-          fatal("Invalid section index in group");
+        if (SecIndex >= Size) {
+          error("Invalid section index in group");
+          return false;
+        }
         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);
-      fatal(ErrorOrTable);
+      if (error(ErrorOrTable, "corrupted file"))
+        return false;
       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)
-        fatal("Invalid relocated section index");
+      if (RelocatedSectionIndex >= Size) {
+        error("Invalid relocated section index");
+        return false;
+      }
       InputSectionBase<ELFT> *RelocatedSection =
           Sections[RelocatedSectionIndex];
-      if (!RelocatedSection)
-        fatal("Unsupported relocation reference");
+      if (!RelocatedSection) {
+        error("Unsupported relocation reference");
+        return false;
+      }
       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)
-          fatal("Multiple relocation sections to .eh_frame are not supported");
-        S->RelocSection = &Sec;
-      } else {
-        fatal("Relocations pointing to SHF_MERGE are not supported");
+        break;
       }
+      if (auto *S = dyn_cast<EHInputSection<ELFT>>(RelocatedSection)) {
+        if (S->RelocSection) {
+          error("Multiple relocation sections to .eh_frame are not supported");
+          return false;
+        }
+        S->RelocSection = &Sec;
         break;
       }
+      error("Relocations pointing to SHF_MERGE are not supported");
+      return false;
+    }
     default:
-      Sections[I] = createInputSection(Sec);
+      ErrorOr<StringRef> NameOrErr = this->ELFObj.getSectionName(&Sec);
+      if (error(NameOrErr, "corrupted file"))
+        return false;
+      Sections[I] = createInputSection(Sec, *NameOrErr);
     }
   }
+  return true;
 }
 
 template <class ELFT> InputSectionBase<ELFT> *
-ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
-  ErrorOr<StringRef> NameOrErr = this->ELFObj.getSectionName(&Sec);
-  fatal(NameOrErr);
-  StringRef Name = *NameOrErr;
-
+ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec, StringRef Name) {
   // .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 (Alloc) MipsReginfoInputSection<ELFT>(this, &Sec);
     return MipsReginfo;
   }
 
   if (Name == ".eh_frame")
     return new (EHAlloc.Allocate()) EHInputSection<ELFT>(this, &Sec);
   if (shouldMerge<ELFT>(Sec))
     return new (MAlloc.Allocate()) MergeInputSection<ELFT>(this, &Sec);
   return new (Alloc) InputSection<ELFT>(this, &Sec);
 }
 
-template <class ELFT> void ObjectFile<ELFT>::initializeSymbols() {
-  this->initStringTable();
+template <class ELFT> bool ObjectFile<ELFT>::initializeSymbols() {
+  if (!this->initStringTable())
+    return false;
   Elf_Sym_Range Syms = this->getNonLocalSymbols();
   uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
   SymbolBodies.reserve(NumSymbols);
-  for (const Elf_Sym &Sym : Syms)
-    SymbolBodies.push_back(createSymbolBody(&Sym));
+  for (const Elf_Sym &Sym : Syms) {
+    SymbolBody *B = createSymbolBody(&Sym);
+    if (!B)
+      return false;
+    SymbolBodies.push_back(B);
+  }
+  return true;
 }
 
 template <class ELFT>
 InputSectionBase<ELFT> *
 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])
-    fatal("Invalid section index");
+  if (Index >= Sections.size() || !Sections[Index]) {
+    error("Invalid section index");
+    return nullptr;
+  }
   return Sections[Index];
 }
 
 template <class ELFT>
 SymbolBody *ObjectFile<ELFT>::createSymbolBody(const Elf_Sym *Sym) {
   ErrorOr<StringRef> NameOrErr = Sym->getName(this->StringTable);
-  fatal(NameOrErr);
+  if (error(NameOrErr, "corrupted file"))
+    return nullptr;
   StringRef Name = *NameOrErr;
 
   switch (Sym->st_shndx) {
   case SHN_UNDEF:
     return new (Alloc) UndefinedElf<ELFT>(Name, *Sym);
   case SHN_COMMON:
     return new (Alloc) DefinedCommon(Name, Sym->st_size, Sym->st_value,
                                      Sym->getBinding() == llvm::ELF::STB_WEAK,
                                      Sym->getVisibility());
   }
 
   switch (Sym->getBinding()) {
   default:
-    fatal("unexpected binding");
+    error("unexpected binding");
+    return nullptr;
   case STB_GLOBAL:
   case STB_WEAK:
   case STB_GNU_UNIQUE: {
     InputSectionBase<ELFT> *Sec = getSection(*Sym);
     if (Sec == &InputSection<ELFT>::Discarded)
       return new (Alloc) UndefinedElf<ELFT>(Name, *Sym);
     return new (Alloc) DefinedRegular<ELFT>(Name, *Sym, Sec);
   }
   }
 }
 
-void ArchiveFile::parse() {
+bool ArchiveFile::parse() {
   ErrorOr<std::unique_ptr<Archive>> FileOrErr = Archive::create(MB);
-  fatal(FileOrErr, "Failed to parse archive");
+  if (error(FileOrErr, "Failed to parse archive"))
+    return false;
   File = std::move(*FileOrErr);
 
   // 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);
+  return true;
 }
 
 // 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();
-  fatal(COrErr, "Could not get the member for symbol " + Sym->getName());
+  if (error(COrErr, "Could not get the member for symbol " + Sym->getName()))
+    return MemoryBufferRef();
   const Archive::Child &C = *COrErr;
 
   if (!Seen.insert(C.getChildOffset()).second)
     return MemoryBufferRef();
 
   ErrorOr<MemoryBufferRef> RefOrErr = C.getMemoryBufferRef();
-  if (!RefOrErr)
-    fatal(RefOrErr, "Could not get the buffer for the member defining symbol " +
-          Sym->getName());
+  if (error(RefOrErr, "Could not get the buffer for the member defining symbol " +
+            Sym->getName()))
+    return MemoryBufferRef();
   return *RefOrErr;
 }
 
 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);
-  fatal(Ret);
+  if (error(Ret, "corrupted file"))
+    return nullptr;
   return *Ret;
 }
 
 // Partially parse the shared object file so that we can call
 // getSoName on this object.
-template <class ELFT> void SharedFile<ELFT>::parseSoName() {
+template <class ELFT> bool 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);
-      fatal(ErrorOrTable);
+      if (error(ErrorOrTable, "corrupted file"))
+        return false;
       this->SymtabSHNDX = *ErrorOrTable;
       break;
     }
     }
   }
 
-  this->initStringTable();
+  if (!this->initStringTable())
+    return false;
   SoName = this->getName();
 
   if (!DynamicSec)
-    return;
+    return true;
   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())
-        fatal("Invalid DT_SONAME entry");
+      if (Val >= this->StringTable.size()) {
+        error("Invalid DT_SONAME entry");
+        return false;
+      }
       SoName = StringRef(this->StringTable.data() + Val);
-      return;
+      return true;
     }
   }
+  return true;
 }
 
 // Fully parse the shared object file. This must be called after parseSoName().
-template <class ELFT> void SharedFile<ELFT>::parseRest() {
+template <class ELFT> bool SharedFile<ELFT>::parseRest() {
   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);
-    fatal(NameOrErr.getError());
+    if (error(NameOrErr, "Failed to get a string table"))
+      return false;
     StringRef Name = *NameOrErr;
 
     if (Sym.isUndefined())
       Undefs.push_back(Name);
     else
       SymbolBodies.emplace_back(this, Name, Sym);
   }
+  return true;
 }
 
 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>
 static std::unique_ptr<InputFile> createELFFile(MemoryBufferRef MB) {
   std::pair<unsigned char, unsigned char> Type = getElfArchType(MB.getBuffer());
-  if (Type.second != ELF::ELFDATA2LSB && Type.second != ELF::ELFDATA2MSB)
-    fatal("Invalid data encoding: " + MB.getBufferIdentifier());
+  if (Type.second != ELF::ELFDATA2LSB && Type.second != ELF::ELFDATA2MSB) {
+    error("Invalid data encoding: " + MB.getBufferIdentifier());
+    return nullptr;
+  }
 
   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);
   }
-  fatal("Invalid file class: " + MB.getBufferIdentifier());
+  error("Invalid file class: " + MB.getBufferIdentifier());
+  return nullptr;
 }
 
 std::unique_ptr<InputFile> elf2::createObjectFile(MemoryBufferRef MB) {
   return createELFFile<ObjectFile>(MB);
 }
 
 std::unique_ptr<InputFile> elf2::createSharedFile(MemoryBufferRef MB) {
   return createELFFile<SharedFile>(MB);

ELF/SymbolTable.cpp

 void SymbolTable<ELFT>::addFile(std::unique_ptr<InputFile> File) {
   if (!isCompatible<ELFT>(File.get()))
     return;
   InputFile *FileP = File.get();
 
   // .a file
   if (auto *F = dyn_cast<ArchiveFile>(FileP)) {
     ArchiveFiles.emplace_back(cast<ArchiveFile>(File.release()));
-    F->parse();
+    if (!F->parse())
+      return;
     for (Lazy &Sym : F->getLazySymbols())
       addLazy(&Sym);
     return;
   }
 
   // .so file
   if (auto *F = dyn_cast<SharedFile<ELFT>>(FileP)) {
     // DSOs are uniquified not by filename but by soname.
-    F->parseSoName();
+    if (!F->parseSoName())
+      return;
     if (!SoNames.insert(F->getSoName()).second)
       return;
 
     SharedFiles.emplace_back(cast<SharedFile<ELFT>>(File.release()));
-    F->parseRest();
+    if (!F->parseRest())
+      return;
     for (SharedSymbol<ELFT> &B : F->getSharedSymbols())
       resolve(&B);
     return;
   }
 
   // .o file
   auto *F = cast<ObjectFile<ELFT>>(FileP);
   ObjectFiles.emplace_back(cast<ObjectFile<ELFT>>(File.release()));
-  F->parse(ComdatGroups);
+  if (!F->parse(ComdatGroups))
+    return;
   for (SymbolBody *B : F->getSymbols())
     resolve(B);
 }
 
 // Add an undefined symbol.
 template <class ELFT>
 SymbolBody *SymbolTable<ELFT>::addUndefined(StringRef Name) {
   auto *Sym = new (Alloc) Undefined(Name, false, STV_DEFAULT, false);