From fad138dd79d025229433c9de90108df4eb81f4af Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Tue, 11 Oct 2011 00:15:42 +0000
Subject: [PATCH] Add support for reading many-section ELF files. If you want
 to tackle adding the testcase, let me know. It's a 4.2MB ELF file and I'll be
 happy to mail it to you.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141605 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Object/ELFObjectFile.cpp | 47 ++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/lib/Object/ELFObjectFile.cpp b/lib/Object/ELFObjectFile.cpp
index 16e9d14ce60..550e241a31b 100644
--- a/lib/Object/ELFObjectFile.cpp
+++ b/lib/Object/ELFObjectFile.cpp
@@ -314,10 +314,10 @@ class ELFObjectFile : public ObjectFile {
   const T        *getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
   const Elf_Sym  *getSymbol(DataRefImpl Symb) const;
   const Elf_Shdr *getSection(DataRefImpl index) const;
-  const Elf_Shdr *getSection(uint16_t index) const;
+  const Elf_Shdr *getSection(uint32_t index) const;
   const Elf_Rel  *getRel(DataRefImpl Rel) const;
   const Elf_Rela *getRela(DataRefImpl Rela) const;
-  const char     *getString(uint16_t section, uint32_t offset) const;
+  const char     *getString(uint32_t section, uint32_t offset) const;
   const char     *getString(const Elf_Shdr *section, uint32_t offset) const;
   error_code      getSymbolName(const Elf_Sym *Symb, StringRef &Res) const;
 
@@ -371,6 +371,9 @@ public:
   virtual uint8_t getBytesInAddress() const;
   virtual StringRef getFileFormatName() const;
   virtual unsigned getArch() const;
+
+  uint64_t getNumSections() const;
+  uint64_t getStringTableIndex() const;
 };
 } // end namespace
 
@@ -1067,16 +1070,15 @@ ELFObjectFile<target_endianness, is64Bits>::ELFObjectFile(MemoryBuffer *Object
 
   SectionHeaderTable =
     reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
-  uint32_t SectionTableSize = Header->e_shnum * Header->e_shentsize;
+  uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
   if (!(  (const uint8_t *)SectionHeaderTable + SectionTableSize
          <= base() + Data->getBufferSize()))
     // FIXME: Proper error handling.
     report_fatal_error("Section table goes past end of file!");
 
-
-  // To find the symbol tables we walk the section table to find SHT_STMTAB.
+  // To find the symbol tables we walk the section table to find SHT_SYMTAB.
   const Elf_Shdr* sh = reinterpret_cast<const Elf_Shdr*>(SectionHeaderTable);
-  for (unsigned i = 0; i < Header->e_shnum; ++i) {
+  for (uint64_t i = 0, e = getNumSections(); i != e; ++i) {
     if (sh->sh_type == ELF::SHT_SYMTAB) {
       SymbolTableSectionsIndexMap[i] = SymbolTableSections.size();
       SymbolTableSections.push_back(sh);
@@ -1094,7 +1096,7 @@ ELFObjectFile<target_endianness, is64Bits>::ELFObjectFile(MemoryBuffer *Object
   }
 
   // Get string table sections.
-  dot_shstrtab_sec = getSection(Header->e_shstrndx);
+  dot_shstrtab_sec = getSection(getStringTableIndex());
   if (dot_shstrtab_sec) {
     // Verify that the last byte in the string table in a null.
     if (((const char*)base() + dot_shstrtab_sec->sh_offset)
@@ -1105,7 +1107,7 @@ ELFObjectFile<target_endianness, is64Bits>::ELFObjectFile(MemoryBuffer *Object
 
   // Merge this into the above loop.
   for (const char *i = reinterpret_cast<const char *>(SectionHeaderTable),
-                  *e = i + Header->e_shnum * Header->e_shentsize;
+                  *e = i + getNumSections() * Header->e_shentsize;
                    i != e; i += Header->e_shentsize) {
     const Elf_Shdr *sh = reinterpret_cast<const Elf_Shdr*>(i);
     if (sh->sh_type == ELF::SHT_STRTAB) {
@@ -1165,7 +1167,7 @@ section_iterator ELFObjectFile<target_endianness, is64Bits>
   memset(&ret, 0, sizeof(DataRefImpl));
   ret.p = reinterpret_cast<intptr_t>(base()
                                      + Header->e_shoff
-                                     + (Header->e_shentsize * Header->e_shnum));
+                                     + (Header->e_shentsize*getNumSections()));
   return section_iterator(SectionRef(ret, this));
 }
 
@@ -1218,6 +1220,25 @@ unsigned ELFObjectFile<target_endianness, is64Bits>::getArch() const {
   }
 }
 
+template<support::endianness target_endianness, bool is64Bits>
+uint64_t ELFObjectFile<target_endianness, is64Bits>::getNumSections() const {
+  if (Header->e_shnum == ELF::SHN_UNDEF)
+    return SectionHeaderTable->sh_size;
+  return Header->e_shnum;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+uint64_t
+ELFObjectFile<target_endianness, is64Bits>::getStringTableIndex() const {
+  if (Header->e_shnum == ELF::SHN_UNDEF) {
+    if (Header->e_shstrndx == ELF::SHN_HIRESERVE)
+      return SectionHeaderTable->sh_link;
+    if (Header->e_shstrndx >= getNumSections())
+      return 0;
+  }
+  return Header->e_shstrndx;
+}
+
 
 template<support::endianness target_endianness, bool is64Bits>
 template<typename T>
@@ -1268,10 +1289,10 @@ ELFObjectFile<target_endianness, is64Bits>::getSection(DataRefImpl Symb) const {
 
 template<support::endianness target_endianness, bool is64Bits>
 const typename ELFObjectFile<target_endianness, is64Bits>::Elf_Shdr *
-ELFObjectFile<target_endianness, is64Bits>::getSection(uint16_t index) const {
-  if (index == 0 || index >= ELF::SHN_LORESERVE)
+ELFObjectFile<target_endianness, is64Bits>::getSection(uint32_t index) const {
+  if (index == 0)
     return 0;
-  if (!SectionHeaderTable || index >= Header->e_shnum)
+  if (!SectionHeaderTable || index >= getNumSections())
     // FIXME: Proper error handling.
     report_fatal_error("Invalid section index!");
 
@@ -1282,7 +1303,7 @@ ELFObjectFile<target_endianness, is64Bits>::getSection(uint16_t index) const {
 
 template<support::endianness target_endianness, bool is64Bits>
 const char *ELFObjectFile<target_endianness, is64Bits>
-                         ::getString(uint16_t section,
+                         ::getString(uint32_t section,
                                      ELF::Elf32_Word offset) const {
   return getString(getSection(section), offset);
 }
-- 
2.34.1