[PATCH] D66063: [Object] Create MutableELFObject Class for Doing Mutations on ELFObjectFiles [Part 5]

[Alex Brachet via Phabricator via llvm-commits]

abrachet created this revision.
abrachet added reviewers: jhenderson, rupprecht.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Micro patch to add ability to modify the files header


https://reviews.llvm.org/D66063

Files:
  llvm/include/llvm/Object/MutableELFObject.h
  llvm/unittests/Object/MutableELFObjectTest.cpp


Index: llvm/unittests/Object/MutableELFObjectTest.cpp
===================================================================
--- llvm/unittests/Object/MutableELFObjectTest.cpp
+++ llvm/unittests/Object/MutableELFObjectTest.cpp
@@ -563,3 +563,24 @@
   ASSERT_THAT_EXPECTED(NameOrErr, Succeeded());
   EXPECT_EQ(*NameOrErr, "newsym");
 }
+
+TEST(MutableELFObject, UpdateHeader) {
+  SmallString<0> Storage;
+  Expected<std::unique_ptr<ObjectFile>> ErrOrObj = yaml2ObjectFile(Storage, R"(
+--- !ELF
+FileHeader:
+  Class:     ELFCLASS64
+  Data:      ELFDATA2LSB
+  Type:      ET_REL
+  Machine:   EM_X86_64)");
+
+  ASSERT_THAT_EXPECTED(ErrOrObj, Succeeded());
+  auto *ELFObjFile = dyn_cast<ELFObjectFile<ELF64LE>>(ErrOrObj->get());
+  ASSERT_TRUE(ELFObjFile);
+  MutableELFObject<ELF64LE> MutableObject(std::move(*ELFObjFile));
+
+  Elf_Ehdr_Impl<ELF64LE> &Header = MutableObject.getHeader();
+  EXPECT_EQ(Header.e_type, ELF::ET_REL);
+  Header.e_type = ELF::ET_EXEC;
+  EXPECT_EQ(MutableObject.getHeader().e_type, ELF::ET_EXEC);
+}
Index: llvm/include/llvm/Object/MutableELFObject.h
===================================================================
--- llvm/include/llvm/Object/MutableELFObject.h
+++ llvm/include/llvm/Object/MutableELFObject.h
@@ -216,13 +216,12 @@
 
   using MutableSymbolTable = MutableTable<Elf_Sym, MutableELFSymbol<ELFT>>;
 
+  Elf_Ehdr FileHeader;
   MutableTable<Elf_Shdr, MutableELFSection<ELFT>> Sections;
   MutableSymbolTable Symbols;
   MutableSymbolTable DynSymbols;
 
-  const Elf_Ehdr &getHeader() const {
-    return *reinterpret_cast<const Elf_Ehdr *>(this->base());
-  }
+  const Elf_Ehdr &getHeader() const { return FileHeader; }
 
   /// Many getSection* methods in ELFObjectFile use getSection to get the
   /// the header associated with that section. This override returns a valid
@@ -259,6 +258,7 @@
 public:
   explicit MutableELFObject(ELFObjectFile<ELFT> &&B)
       : ELFObjectFile<ELFT>(std::move(B)),
+        FileHeader(*reinterpret_cast<const Elf_Ehdr *>(this->base())),
         Sections(ArrayRef<Elf_Shdr>(reinterpret_cast<const Elf_Shdr *>(
                                         this->base() + getHeader().e_shoff),
                                     getHeader().e_shnum)),
@@ -376,6 +376,8 @@
 
   /// Removes a section.
   void removeSection(section_iterator Sec) { removeSection(*Sec); }
+
+  Elf_Ehdr &getHeader() { return FileHeader; }
 };
 
 template <typename ELFT>


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