[PATCH] D60555: [llvm-objcopy] Fill .symtab_shndx section correctly

[Eugene Leviant via Phabricator via llvm-commits]

evgeny777 created this revision.
evgeny777 added reviewers: rupprecht, jakehehrlich, jhenderson.
Herald added subscribers: MaskRay, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a reviewer: alexshap.

This fixes https://bugs.llvm.org/show_bug.cgi?id=41461

However I have problem with test case, which requires 19MB binary file. Any help is appreciated.


https://reviews.llvm.org/D60555

Files:
  tools/llvm-objcopy/ELF/Object.cpp
  tools/llvm-objcopy/ELF/Object.h


Index: tools/llvm-objcopy/ELF/Object.h
===================================================================
--- tools/llvm-objcopy/ELF/Object.h
+++ tools/llvm-objcopy/ELF/Object.h
@@ -481,9 +481,14 @@
 public:
   virtual ~SectionIndexSection() {}
   void addIndex(uint32_t Index) {
-    Indexes.push_back(Index);
-    Size += 4;
+    assert(Size);
+    Indexes.push_back(Index);    
   }
+
+  void reserve(size_t NumSymbols) {
+    Indexes.reserve(NumSymbols);
+    Size = NumSymbols * 4;
+  }  
   void setSymTab(SymbolTableSection *SymTab) { Symbols = SymTab; }
   void initialize(SectionTableRef SecTable) override;
   void finalize() override;
@@ -524,6 +529,7 @@
     SectionIndexTable = ShndxTable;
   }
   const SectionIndexSection *getShndxTable() const { return SectionIndexTable; }
+  void fillShndxTable();
   const SectionBase *getStrTab() const { return SymbolNames; }
   const Symbol *getSymbolByIndex(uint32_t Index) const;
   Symbol *getSymbolByIndex(uint32_t Index);
Index: tools/llvm-objcopy/ELF/Object.cpp
===================================================================
--- tools/llvm-objcopy/ELF/Object.cpp
+++ tools/llvm-objcopy/ELF/Object.cpp
@@ -488,20 +488,25 @@
 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);
-    }
-  }
+  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;
+  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 +1666,11 @@
 
   assignOffsets();
 
+  // layoutSections could have modified section indexes, that why we need
+  // to fill 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);


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