[llvm-objcopy] Fill .symtab_shndx section correctly

Differential revision: https://reviews.llvm.org/D60555

llvm-svn: 358278

1 files changed, 23 insertions, 10 deletions

diff --git a/llvm/tools/llvm-objcopy/ELF/Object.cpp b/llvm/tools/llvm-objcopy/ELF/Object.cpp
index de51851..979ab0a 100644
--- a/llvm/tools/llvm-objcopy/ELF/Object.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/Object.cpp
@@ -486,22 +486,30 @@ void SymbolTableSection::finalize() {
 }
 
 void SymbolTableSection::prepareForLayout() {
-  // Add all potential section indexes before file layout so that the section
-  // index section has the approprite size.
-  if (SectionIndexTable != nullptr) {
-    for (const auto &Sym : Symbols) {
-      if (Sym->DefinedIn != nullptr && Sym->DefinedIn->Index >= SHN_LORESERVE)
-        SectionIndexTable->addIndex(Sym->DefinedIn->Index);
-      else
-        SectionIndexTable->addIndex(SHN_UNDEF);
-    }
-  }
+  // Reserve proper amount of space in section index table, so we can
+  // layout sections correctly. We will fill the table with correct
+  // indexes later in fillShdnxTable.
+  if (SectionIndexTable)  
+    SectionIndexTable->reserve(Symbols.size());
   // Add all of our strings to SymbolNames so that SymbolNames has the right
   // size before layout is decided.
   for (auto &Sym : Symbols)
     SymbolNames->addString(Sym->Name);
 }
 
+void SymbolTableSection::fillShndxTable() {
+  if (SectionIndexTable == nullptr)
+    return;
+  // Fill section index table with real section indexes. This function must
+  // be called after assignOffsets.
+  for (const auto &Sym : Symbols) {
+    if (Sym->DefinedIn != nullptr && Sym->DefinedIn->Index >= SHN_LORESERVE)
+      SectionIndexTable->addIndex(Sym->DefinedIn->Index);
+    else
+      SectionIndexTable->addIndex(SHN_UNDEF);
+  }
+}
+
 const Symbol *SymbolTableSection::getSymbolByIndex(uint32_t Index) const {
   if (Symbols.size() <= Index)
     error("Invalid symbol index: " + Twine(Index));
@@ -1661,6 +1669,11 @@ template <class ELFT> Error ELFWriter<ELFT>::finalize() {
 
   assignOffsets();
 
+  // layoutSections could have modified section indexes, so we need
+  // to fill the index table after assignOffsets.
+  if (Obj.SymbolTable != nullptr)
+    Obj.SymbolTable->fillShndxTable();
+
   // Finally now that all offsets and indexes have been set we can finalize any
   // remaining issues.
   uint64_t Offset = Obj.SHOffset + sizeof(Elf_Shdr);