From e84f5aaedfe46d847303e694cd1c8823fe8ff09d Mon Sep 17 00:00:00 2001
From: Xing GUO <higuoxing@gmail.com>
Date: Thu, 28 Mar 2019 12:51:35 +0000
Subject: [PATCH] [llvm-readobj] Add new helper function
 `getSymbolVersionByIndex()`

Summary: When implementing `GNU style` dumper for `.gnu.version` section, we should find symbol version name by `vs_index`.

Reviewers: jhenderson, rupprecht

Reviewed By: rupprecht

Subscribers: arphaman, rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59545

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@357164 91177308-0d34-0410-b5e6-96231b3b80d8
---
 tools/llvm-readobj/ELFDumper.cpp | 75 ++++++++++++++++++--------------
 1 file changed, 43 insertions(+), 32 deletions(-)

diff --git a/tools/llvm-readobj/ELFDumper.cpp b/tools/llvm-readobj/ELFDumper.cpp
index 091456329f9..89257e833d4 100644
--- a/tools/llvm-readobj/ELFDumper.cpp
+++ b/tools/llvm-readobj/ELFDumper.cpp
@@ -274,6 +274,9 @@ public:
                            StringRef &SectionName,
                            unsigned &SectionIndex) const;
   std::string getStaticSymbolName(uint32_t Index) const;
+	std::string getSymbolVersionByIndex(StringRef StrTab,
+	                                const uint32_t VersionSymbolIndex,
+                                  bool &IsDefault) const;
 
   void printSymbolsHelper(bool IsDynamic) const;
   const Elf_Shdr *getDotSymtabSec() const { return DotSymtabSec; }
@@ -627,7 +630,7 @@ template <class ELFT> void ELFDumper<ELFT>::LoadVersionMap() const {
 
 template <typename ELFT>
 StringRef ELFDumper<ELFT>::getSymbolVersion(StringRef StrTab,
-                                            const Elf_Sym *symb,
+                                            const Elf_Sym *Sym,
                                             bool &IsDefault) const {
   // This is a dynamic symbol. Look in the GNU symbol version table.
   if (!dot_gnu_version_sec) {
@@ -637,41 +640,16 @@ StringRef ELFDumper<ELFT>::getSymbolVersion(StringRef StrTab,
   }
 
   // Determine the position in the symbol table of this entry.
-  size_t entry_index = (reinterpret_cast<uintptr_t>(symb) -
+  size_t EntryIndex = (reinterpret_cast<uintptr_t>(Sym) -
                         reinterpret_cast<uintptr_t>(DynSymRegion.Addr)) /
                        sizeof(Elf_Sym);
 
   // Get the corresponding version index entry
-  const Elf_Versym *vs = unwrapOrError(
-      ObjF->getELFFile()->template getEntry<Elf_Versym>(dot_gnu_version_sec, entry_index));
-  size_t version_index = vs->vs_index & ELF::VERSYM_VERSION;
-
-  // Special markers for unversioned symbols.
-  if (version_index == ELF::VER_NDX_LOCAL ||
-      version_index == ELF::VER_NDX_GLOBAL) {
-    IsDefault = false;
-    return StringRef("");
-  }
-
-  // Lookup this symbol in the version table
-  LoadVersionMap();
-  if (version_index >= VersionMap.size() || VersionMap[version_index].isNull())
-    reportError("Invalid version entry");
-  const VersionMapEntry &entry = VersionMap[version_index];
-
-  // Get the version name string
-  size_t name_offset;
-  if (entry.isVerdef()) {
-    // The first Verdaux entry holds the name.
-    name_offset = entry.getVerdef()->getAux()->vda_name;
-    IsDefault = !(vs->vs_index & ELF::VERSYM_HIDDEN);
-  } else {
-    name_offset = entry.getVernaux()->vna_name;
-    IsDefault = false;
-  }
-  if (name_offset >= StrTab.size())
-    reportError("Invalid string offset");
-  return StringRef(StrTab.data() + name_offset);
+  const Elf_Versym *Versym =
+      unwrapOrError(ObjF->getELFFile()->template getEntry<Elf_Versym>(
+          dot_gnu_version_sec, EntryIndex));
+  return StringRef(
+      this->getSymbolVersionByIndex(StrTab, Versym->vs_index, IsDefault));
 }
 
 static std::string maybeDemangle(StringRef Name) {
@@ -689,6 +667,39 @@ std::string ELFDumper<ELFT>::getStaticSymbolName(uint32_t Index) const {
   return maybeDemangle(unwrapOrError(Sym->getName(StrTable)));
 }
 
+template <typename ELFT>
+std::string ELFDumper<ELFT>::getSymbolVersionByIndex(
+    StringRef StrTab, const uint32_t SymbolVersionIndex, bool &IsDefault) const {
+  size_t VersionIndex = SymbolVersionIndex & VERSYM_VERSION;
+
+  // Special markers for unversioned symbols.
+  if (VersionIndex == VER_NDX_LOCAL ||
+      VersionIndex == VER_NDX_GLOBAL) {
+    IsDefault = false;
+    return "";
+  }
+
+  // Lookup this symbol in the version table
+  LoadVersionMap();
+  if (VersionIndex >= VersionMap.size() || VersionMap[VersionIndex].isNull())
+    reportError("Invalid version entry");
+  const VersionMapEntry &Entry = VersionMap[VersionIndex];
+
+  // Get the version name string
+  size_t NameOffset;
+  if (Entry.isVerdef()) {
+    // The first Verdaux entry holds the name.
+    NameOffset = Entry.getVerdef()->getAux()->vda_name;
+    IsDefault = !(SymbolVersionIndex & VERSYM_HIDDEN);
+  } else {
+    NameOffset = Entry.getVernaux()->vna_name;
+    IsDefault = false;
+  }
+  if (NameOffset >= StrTab.size())
+    reportError("Invalid string offset");
+  return std::string(StrTab.data() + NameOffset);
+}
+
 template <typename ELFT>
 std::string ELFDumper<ELFT>::getFullSymbolName(const Elf_Sym *Symbol,
                                                StringRef StrTable,
-- 
2.40.0