Revert "[llvm-objcopy] Add support for .dynamic, .dynsym, and .dynstr"

This reverts commit r313663. Broken because overlapping-sections was
reverted.

llvm-svn: 313665

Author: jakehehrlich

llvm/test/tools/llvm-objcopy/Inputs/dynamic.so

@@ -228,12 +228,6 @@ void RelocationSection<ELFT>::writeSection(llvm::FileOutputBuffer &Out) const {
     writeRel(reinterpret_cast<Elf_Rela *>(Buf));
 }
 
-bool SectionWithStrTab::classof(const SectionBase *S) {
-  return isa<DynamicSymbolTableSection>(S) || isa<DynamicSection>(S);
-}
-
-void SectionWithStrTab::finalize() { this->Link = StrTab->Index; }
-
 // Returns true IFF a section is wholly inside the range of a segment
 static bool sectionWithinSegment(const SectionBase &Section,
                                  const Segment &Segment) {
@@ -281,20 +275,23 @@ void Object<ELFT>::initSymbolTable(const llvm::object::ELFFile<ELFT> &ElfFile,
                                    SymbolTableSection *SymTab) {
 
   SymTab->Size = 0;
-  SymTab->setStrTab(getSectionOfType<StringTableSection>(
-      SymbolTable->Link,
-      "Symbol table has link index of " + Twine(SymTab->Link) +
-          " which is not a valid index",
-      "Symbol table has link index of " + Twine(SymTab->Link) +
-          " which is not a string table"));
+  if (SymbolTable->Link - 1 >= Sections.size())
+    error("Symbol table has link index of " + Twine(SymbolTable->Link) +
+          " which is not a valid index");
+
+  if (auto StrTab =
+          dyn_cast<StringTableSection>(Sections[SymbolTable->Link - 1].get()))
+    SymTab->setStrTab(StrTab);
+  else
+    error("Symbol table has link index of " + Twine(SymbolTable->Link) +
+          "which is not a string table");
 
   const Elf_Shdr &Shdr = *unwrapOrError(ElfFile.getSection(SymTab->Index));
   StringRef StrTabData = unwrapOrError(ElfFile.getStringTableForSymtab(Shdr));
 
   for (const auto &Sym : unwrapOrError(ElfFile.symbols(&Shdr))) {
     SectionBase *DefSection = nullptr;
     StringRef Name = unwrapOrError(Sym.getName(StrTabData));
-
     if (Sym.st_shndx >= SHN_LORESERVE) {
       if (!isValidReservedSectionIndex(Sym.st_shndx, Machine)) {
         error(
@@ -303,12 +300,12 @@ void Object<ELFT>::initSymbolTable(const llvm::object::ELFFile<ELFT> &ElfFile,
             Twine(Sym.st_shndx));
       }
     } else if (Sym.st_shndx != SHN_UNDEF) {
-      DefSection = getSection(
-          Sym.st_shndx,
-          "Symbol '" + Name + "' is defined in invalid section with index " +
+      if (Sym.st_shndx >= Sections.size())
+        error("Symbol '" + Name +
+              "' is defined in invalid section with index " +
               Twine(Sym.st_shndx));
+      DefSection = Sections[Sym.st_shndx - 1].get();
     }
-
     SymTab->addSymbol(Name, Sym.getBinding(), Sym.getType(), DefSection,
                       Sym.getValue(), Sym.st_shndx, Sym.st_size);
   }
@@ -335,22 +332,6 @@ void initRelocations(RelocationSection<ELFT> *Relocs,
   }
 }
 
-template <class ELFT>
-SectionBase *Object<ELFT>::getSection(uint16_t Index, Twine ErrMsg) {
-  if (Index == SHN_UNDEF || Index > Sections.size())
-    error(ErrMsg);
-  return Sections[Index - 1].get();
-}
-
-template <class ELFT>
-template <class T>
-T *Object<ELFT>::getSectionOfType(uint16_t Index, Twine IndexErrMsg,
-                                  Twine TypeErrMsg) {
-  if (T *TSec = llvm::dyn_cast<T>(getSection(Index, IndexErrMsg)))
-    return TSec;
-  error(TypeErrMsg);
-}
-
 template <class ELFT>
 std::unique_ptr<SectionBase>
 Object<ELFT>::makeSection(const llvm::object::ELFFile<ELFT> &ElfFile,
@@ -361,26 +342,7 @@ Object<ELFT>::makeSection(const llvm::object::ELFFile<ELFT> &ElfFile,
   case SHT_RELA:
     return llvm::make_unique<RelocationSection<ELFT>>();
   case SHT_STRTAB:
-    // If a string table is allocated we don't want to mess with it. That would
-    // mean altering the memory image. There are no special link types or
-    // anything so we can just use a Section.
-    if (Shdr.sh_flags & SHF_ALLOC) {
-      Data = unwrapOrError(ElfFile.getSectionContents(&Shdr));
-      return llvm::make_unique<Section>(Data);
-    }
     return llvm::make_unique<StringTableSection>();
-  case SHT_HASH:
-  case SHT_GNU_HASH:
-    // Hash tables should refer to SHT_DYNSYM which we're not going to change.
-    // Because of this we don't need to mess with the hash tables either.
-    Data = unwrapOrError(ElfFile.getSectionContents(&Shdr));
-    return llvm::make_unique<Section>(Data);
-  case SHT_DYNSYM:
-    Data = unwrapOrError(ElfFile.getSectionContents(&Shdr));
-    return llvm::make_unique<DynamicSymbolTableSection>(Data);
-  case SHT_DYNAMIC:
-    Data = unwrapOrError(ElfFile.getSectionContents(&Shdr));
-    return llvm::make_unique<DynamicSection>(Data);
   case SHT_SYMTAB: {
     auto SymTab = llvm::make_unique<SymbolTableSectionImpl<ELFT>>();
     SymbolTable = SymTab.get();
@@ -428,35 +390,28 @@ void Object<ELFT>::readSectionHeaders(const ELFFile<ELFT> &ElfFile) {
   // relocation sections.
   for (auto &Section : Sections) {
     if (auto RelSec = dyn_cast<RelocationSection<ELFT>>(Section.get())) {
-
-      auto SymTab = getSectionOfType<SymbolTableSection>(
-          RelSec->Link,
-          "Link field value " + Twine(RelSec->Link) + " in section " +
-              RelSec->Name + " is invalid",
-          "Link field value " + Twine(RelSec->Link) + " in section " +
-              RelSec->Name + " is not a symbol table");
+      if (RelSec->Link - 1 >= Sections.size() || RelSec->Link == 0) {
+        error("Link field value " + Twine(RelSec->Link) + " in section " +
+              RelSec->Name + " is invalid");
+      }
+      if (RelSec->Info - 1 >= Sections.size() || RelSec->Info == 0) {
+        error("Info field value " + Twine(RelSec->Link) + " in section " +
+              RelSec->Name + " is invalid");
+      }
+      auto SymTab =
+          dyn_cast<SymbolTableSection>(Sections[RelSec->Link - 1].get());
+      if (SymTab == nullptr) {
+        error("Link field of relocation section " + RelSec->Name +
+              " is not a symbol table");
+      }
       RelSec->setSymTab(SymTab);
-
-      RelSec->setSection(getSection(RelSec->Info,
-                                    "Info field value " + Twine(RelSec->Link) +
-                                        " in section " + RelSec->Name +
-                                        " is invalid"));
-
+      RelSec->setSection(Sections[RelSec->Info - 1].get());
       auto Shdr = unwrapOrError(ElfFile.sections()).begin() + RelSec->Index;
       if (RelSec->Type == SHT_REL)
         initRelocations(RelSec, SymTab, unwrapOrError(ElfFile.rels(Shdr)));
       else
         initRelocations(RelSec, SymTab, unwrapOrError(ElfFile.relas(Shdr)));
     }
-
-    if (auto Sec = dyn_cast<SectionWithStrTab>(Section.get())) {
-      Sec->setStrTab(getSectionOfType<StringTableSection>(
-          Sec->Link,
-          "Link field value " + Twine(Sec->Link) + " in section " + Sec->Name +
-              " is invalid",
-          "Link field value " + Twine(Sec->Link) + " in section " + Sec->Name +
-              " is not a string table"));
-    }
   }
 }
 
@@ -474,12 +429,8 @@ template <class ELFT> Object<ELFT>::Object(const ELFObjectFile<ELFT> &Obj) {
   readSectionHeaders(ElfFile);
   readProgramHeaders(ElfFile);
 
-  SectionNames = getSectionOfType<StringTableSection>(
-      Ehdr.e_shstrndx,
-      "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) + " in elf header " +
-          " is invalid",
-      "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) + " in elf header " +
-          " is not a string table");
+  SectionNames =
+      dyn_cast<StringTableSection>(Sections[Ehdr.e_shstrndx - 1].get());
 }
 
 template <class ELFT>

llvm/test/tools/llvm-objcopy/Inputs/dynsym.so

@@ -193,34 +193,6 @@ template <class ELFT> class RelocationSection : public SectionBase {
   }
 };
 
-class SectionWithStrTab : public Section {
-private:
-  StringTableSection *StrTab;
-
-public:
-  SectionWithStrTab(llvm::ArrayRef<uint8_t> Data) : Section(Data) {}
-  void setStrTab(StringTableSection *StringTable) { StrTab = StringTable; }
-  void finalize() override;
-  static bool classof(const SectionBase *S);
-};
-
-class DynamicSymbolTableSection : public SectionWithStrTab {
-public:
-  DynamicSymbolTableSection(llvm::ArrayRef<uint8_t> Data)
-      : SectionWithStrTab(Data) {}
-  static bool classof(const SectionBase *S) {
-    return S->Type == llvm::ELF::SHT_DYNSYM;
-  }
-};
-
-class DynamicSection : public SectionWithStrTab {
-public:
-  DynamicSection(llvm::ArrayRef<uint8_t> Data) : SectionWithStrTab(Data) {}
-  static bool classof(const SectionBase *S) {
-    return S->Type == llvm::ELF::SHT_DYNAMIC;
-  }
-};
-
 template <class ELFT> class Object {
 private:
   typedef std::unique_ptr<SectionBase> SecPtr;
@@ -237,12 +209,6 @@ template <class ELFT> class Object {
   void readProgramHeaders(const llvm::object::ELFFile<ELFT> &ElfFile);
   void readSectionHeaders(const llvm::object::ELFFile<ELFT> &ElfFile);
 
-  SectionBase *getSection(uint16_t Index, llvm::Twine ErrMsg);
-
-  template <class T>
-  T *getSectionOfType(uint16_t Index, llvm::Twine IndexErrMsg,
-                      llvm::Twine TypeErrMsg);
-
 protected:
   StringTableSection *SectionNames;
   SymbolTableSection *SymbolTable;