[llvm-objcopy][MachO] Support load commands used in executables/shared libraries

Summary:
This patch implements copying some load commands that appear in executables/shared libraries such as the indirect symbol table.

I don't add tests intentionally because this patch is incomplete: we need a layout algorithm for executables/shared libraries. I'll submit it as a separate patch with tests.

Reviewers: alexshap, rupprecht, jhenderson, compnerd

Reviewed By: alexshap

Subscribers: abrachet, mgorny, mgrang, MaskRay, mtrent, jakehehrlich, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63395

llvm-svn: 369230

1 files changed, 41 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
index 23dde7de53d..b48a0d8952d 100644
--- a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
@@ -129,10 +129,19 @@ void MachOReader::readLoadCommands(Object &O) const {
     case MachO::LC_SYMTAB:
       O.SymTabCommandIndex = O.LoadCommands.size();
       break;
+    case MachO::LC_DYSYMTAB:
+      O.DySymTabCommandIndex = O.LoadCommands.size();
+      break;
     case MachO::LC_DYLD_INFO:
     case MachO::LC_DYLD_INFO_ONLY:
       O.DyLdInfoCommandIndex = O.LoadCommands.size();
       break;
+    case MachO::LC_DATA_IN_CODE:
+      O.DataInCodeCommandIndex = O.LoadCommands.size();
+      break;
+    case MachO::LC_FUNCTION_STARTS:
+      O.FunctionStartsCommandIndex = O.LoadCommands.size();
+      break;
     }
 #define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct)                         \
   case MachO::LCName:                                                          \
@@ -222,6 +231,35 @@ void MachOReader::readExportInfo(Object &O) const {
   O.Exports.Trie = MachOObj.getDyldInfoExportsTrie();
 }
 
+void MachOReader::readDataInCodeData(Object &O) const {
+  if (!O.DataInCodeCommandIndex)
+    return;
+  const MachO::linkedit_data_command &LDC =
+      O.LoadCommands[*O.DataInCodeCommandIndex]
+          .MachOLoadCommand.linkedit_data_command_data;
+
+  O.DataInCode.Data = arrayRefFromStringRef(
+      MachOObj.getData().substr(LDC.dataoff, LDC.datasize));
+}
+
+void MachOReader::readFunctionStartsData(Object &O) const {
+  if (!O.FunctionStartsCommandIndex)
+    return;
+  const MachO::linkedit_data_command &LDC =
+      O.LoadCommands[*O.FunctionStartsCommandIndex]
+          .MachOLoadCommand.linkedit_data_command_data;
+
+  O.FunctionStarts.Data = arrayRefFromStringRef(
+      MachOObj.getData().substr(LDC.dataoff, LDC.datasize));
+}
+
+void MachOReader::readIndirectSymbolTable(Object &O) const {
+  MachO::dysymtab_command DySymTab = MachOObj.getDysymtabLoadCommand();
+  for (uint32_t i = 0; i < DySymTab.nindirectsyms; ++i)
+    O.IndirectSymTable.Symbols.push_back(
+        MachOObj.getIndirectSymbolTableEntry(DySymTab, i));
+}
+
 std::unique_ptr<Object> MachOReader::create() const {
   auto Obj = std::make_unique<Object>();
   readHeader(*Obj);
@@ -233,6 +271,9 @@ std::unique_ptr<Object> MachOReader::create() const {
   readWeakBindInfo(*Obj);
   readLazyBindInfo(*Obj);
   readExportInfo(*Obj);
+  readDataInCodeData(*Obj);
+  readFunctionStartsData(*Obj);
+  readIndirectSymbolTable(*Obj);
   return Obj;
 }