Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 935 insertions, 0 deletions

diff --git a/build/unix/elfhack/elf.cpp b/build/unix/elfhack/elf.cpp
new file mode 100644
index 0000000000..b2a21e4901
--- /dev/null
+++ b/build/unix/elfhack/elf.cpp
@@ -0,0 +1,935 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#undef NDEBUG
+#include <cstring>
+#include <assert.h>
+#include "elfxx.h"
+
+template <class endian, typename R, typename T>
+void Elf_Ehdr_Traits::swap(T& t, R& r) {
+  memcpy(r.e_ident, t.e_ident, sizeof(r.e_ident));
+  r.e_type = endian::swap(t.e_type);
+  r.e_machine = endian::swap(t.e_machine);
+  r.e_version = endian::swap(t.e_version);
+  r.e_entry = endian::swap(t.e_entry);
+  r.e_phoff = endian::swap(t.e_phoff);
+  r.e_shoff = endian::swap(t.e_shoff);
+  r.e_flags = endian::swap(t.e_flags);
+  r.e_ehsize = endian::swap(t.e_ehsize);
+  r.e_phentsize = endian::swap(t.e_phentsize);
+  r.e_phnum = endian::swap(t.e_phnum);
+  r.e_shentsize = endian::swap(t.e_shentsize);
+  r.e_shnum = endian::swap(t.e_shnum);
+  r.e_shstrndx = endian::swap(t.e_shstrndx);
+}
+
+template <class endian, typename R, typename T>
+void Elf_Phdr_Traits::swap(T& t, R& r) {
+  r.p_type = endian::swap(t.p_type);
+  r.p_offset = endian::swap(t.p_offset);
+  r.p_vaddr = endian::swap(t.p_vaddr);
+  r.p_paddr = endian::swap(t.p_paddr);
+  r.p_filesz = endian::swap(t.p_filesz);
+  r.p_memsz = endian::swap(t.p_memsz);
+  r.p_flags = endian::swap(t.p_flags);
+  r.p_align = endian::swap(t.p_align);
+}
+
+template <class endian, typename R, typename T>
+void Elf_Shdr_Traits::swap(T& t, R& r) {
+  r.sh_name = endian::swap(t.sh_name);
+  r.sh_type = endian::swap(t.sh_type);
+  r.sh_flags = endian::swap(t.sh_flags);
+  r.sh_addr = endian::swap(t.sh_addr);
+  r.sh_offset = endian::swap(t.sh_offset);
+  r.sh_size = endian::swap(t.sh_size);
+  r.sh_link = endian::swap(t.sh_link);
+  r.sh_info = endian::swap(t.sh_info);
+  r.sh_addralign = endian::swap(t.sh_addralign);
+  r.sh_entsize = endian::swap(t.sh_entsize);
+}
+
+template <class endian, typename R, typename T>
+void Elf_Dyn_Traits::swap(T& t, R& r) {
+  r.d_tag = endian::swap(t.d_tag);
+  r.d_un.d_val = endian::swap(t.d_un.d_val);
+}
+
+template <class endian, typename R, typename T>
+void Elf_Sym_Traits::swap(T& t, R& r) {
+  r.st_name = endian::swap(t.st_name);
+  r.st_value = endian::swap(t.st_value);
+  r.st_size = endian::swap(t.st_size);
+  r.st_info = t.st_info;
+  r.st_other = t.st_other;
+  r.st_shndx = endian::swap(t.st_shndx);
+}
+
+template <class endian>
+struct _Rel_info {
+  static inline void swap(Elf32_Word& t, Elf32_Word& r) { r = endian::swap(t); }
+  static inline void swap(Elf64_Xword& t, Elf64_Xword& r) {
+    r = endian::swap(t);
+  }
+  static inline void swap(Elf64_Xword& t, Elf32_Word& r) {
+    r = endian::swap(ELF32_R_INFO(ELF64_R_SYM(t), ELF64_R_TYPE(t)));
+  }
+  static inline void swap(Elf32_Word& t, Elf64_Xword& r) {
+    r = endian::swap(ELF64_R_INFO(ELF32_R_SYM(t), ELF32_R_TYPE(t)));
+  }
+};
+
+template <class endian, typename R, typename T>
+void Elf_Rel_Traits::swap(T& t, R& r) {
+  r.r_offset = endian::swap(t.r_offset);
+  _Rel_info<endian>::swap(t.r_info, r.r_info);
+}
+
+template <class endian, typename R, typename T>
+void Elf_Rela_Traits::swap(T& t, R& r) {
+  r.r_offset = endian::swap(t.r_offset);
+  _Rel_info<endian>::swap(t.r_info, r.r_info);
+  r.r_addend = endian::swap(t.r_addend);
+}
+
+static const Elf64_Shdr null64_section = {0, SHT_NULL,  0, 0, 0,
+                                          0, SHN_UNDEF, 0, 0, 0};
+
+Elf_Shdr null_section(null64_section);
+
+Elf_Ehdr::Elf_Ehdr(std::ifstream& file, unsigned char ei_class,
+                   unsigned char ei_data)
+    : serializable<Elf_Ehdr_Traits>(file, ei_class, ei_data),
+      ElfSection(null_section, nullptr, nullptr) {
+  shdr.sh_size = Elf_Ehdr::size(ei_class);
+}
+
+Elf::Elf(std::ifstream& file) {
+  if (!file.is_open()) throw std::runtime_error("Error opening file");
+
+  file.exceptions(std::ifstream::eofbit | std::ifstream::failbit |
+                  std::ifstream::badbit);
+  // Read ELF magic number and identification information
+  unsigned char e_ident[EI_VERSION];
+  file.seekg(0);
+  file.read((char*)e_ident, sizeof(e_ident));
+  file.seekg(0);
+  ehdr = new Elf_Ehdr(file, e_ident[EI_CLASS], e_ident[EI_DATA]);
+
+  // ELFOSABI_LINUX is kept unsupported because I haven't looked whether
+  // STB_GNU_UNIQUE or STT_GNU_IFUNC would need special casing.
+  if ((ehdr->e_ident[EI_OSABI] != ELFOSABI_NONE) &&
+      (ehdr->e_ident[EI_ABIVERSION] != 0))
+    throw std::runtime_error("unsupported ELF ABI");
+
+  if (ehdr->e_version != 1) throw std::runtime_error("unsupported ELF version");
+
+  // Sanity checks
+  if (ehdr->e_shnum == 0)
+    throw std::runtime_error("sstripped ELF files aren't supported");
+
+  if (ehdr->e_ehsize != Elf_Ehdr::size(e_ident[EI_CLASS]))
+    throw std::runtime_error(
+        "unsupported ELF inconsistency: ehdr.e_ehsize != sizeof(ehdr)");
+
+  if (ehdr->e_shentsize != Elf_Shdr::size(e_ident[EI_CLASS]))
+    throw std::runtime_error(
+        "unsupported ELF inconsistency: ehdr.e_shentsize != sizeof(shdr)");
+
+  if (ehdr->e_phnum == 0) {
+    if (ehdr->e_phoff != 0)
+      throw std::runtime_error(
+          "unsupported ELF inconsistency: e_phnum == 0 && e_phoff != 0");
+    if (ehdr->e_phentsize != 0)
+      throw std::runtime_error(
+          "unsupported ELF inconsistency: e_phnum == 0 && e_phentsize != 0");
+  } else if (ehdr->e_phoff != ehdr->e_ehsize)
+    throw std::runtime_error(
+        "unsupported ELF inconsistency: ehdr->e_phoff != ehdr->e_ehsize");
+  else if (ehdr->e_phentsize != Elf_Phdr::size(e_ident[EI_CLASS]))
+    throw std::runtime_error(
+        "unsupported ELF inconsistency: ehdr->e_phentsize != sizeof(phdr)");
+
+  // Read section headers
+  Elf_Shdr** shdr = new Elf_Shdr*[ehdr->e_shnum];
+  file.seekg(ehdr->e_shoff);
+  for (int i = 0; i < ehdr->e_shnum; i++)
+    shdr[i] = new Elf_Shdr(file, e_ident[EI_CLASS], e_ident[EI_DATA]);
+
+  // Sanity check in section header for index 0
+  if ((shdr[0]->sh_name != 0) || (shdr[0]->sh_type != SHT_NULL) ||
+      (shdr[0]->sh_flags != 0) || (shdr[0]->sh_addr != 0) ||
+      (shdr[0]->sh_offset != 0) || (shdr[0]->sh_size != 0) ||
+      (shdr[0]->sh_link != SHN_UNDEF) || (shdr[0]->sh_info != 0) ||
+      (shdr[0]->sh_addralign != 0) || (shdr[0]->sh_entsize != 0))
+    throw std::runtime_error(
+        "Section header for index 0 contains unsupported values");
+
+  if ((shdr[ehdr->e_shstrndx]->sh_link != 0) ||
+      (shdr[ehdr->e_shstrndx]->sh_info != 0))
+    throw std::runtime_error(
+        "unsupported ELF content: string table with sh_link != 0 || sh_info != "
+        "0");
+
+  // Store these temporarily
+  tmp_shdr = shdr;
+  tmp_file = &file;
+
+  // Fill sections list
+  sections = new ElfSection*[ehdr->e_shnum];
+  for (int i = 0; i < ehdr->e_shnum; i++) sections[i] = nullptr;
+  for (int i = 1; i < ehdr->e_shnum; i++) {
+    // The .dynamic section is going to have references to other sections,
+    // so it's better to start with that one and recursively initialize those
+    // other sections first, to avoid possible infinite recursion (bug 1606739).
+    if (tmp_shdr[i]->sh_type == SHT_DYNAMIC) {
+      getSection(i);
+    }
+  }
+  for (int i = 1; i < ehdr->e_shnum; i++) {
+    if (sections[i] != nullptr) continue;
+    getSection(i);
+  }
+  Elf_Shdr s;
+  s.sh_name = 0;
+  s.sh_type = SHT_NULL;
+  s.sh_flags = 0;
+  s.sh_addr = 0;
+  s.sh_offset = ehdr->e_shoff;
+  s.sh_entsize = Elf_Shdr::size(e_ident[EI_CLASS]);
+  s.sh_size = s.sh_entsize * ehdr->e_shnum;
+  s.sh_link = 0;
+  s.sh_info = 0;
+  s.sh_addralign = (e_ident[EI_CLASS] == ELFCLASS32) ? 4 : 8;
+  shdr_section = new ElfSection(s, nullptr, nullptr);
+
+  // Fake section for program headers
+  s.sh_offset = ehdr->e_phoff;
+  s.sh_addr = ehdr->e_phoff;
+  s.sh_entsize = Elf_Phdr::size(e_ident[EI_CLASS]);
+  s.sh_size = s.sh_entsize * ehdr->e_phnum;
+  phdr_section = new ElfSection(s, nullptr, nullptr);
+
+  phdr_section->insertAfter(ehdr, false);
+
+  sections[1]->insertAfter(phdr_section, false);
+  for (int i = 2; i < ehdr->e_shnum; i++) {
+    // TODO: this should be done in a better way
+    if ((shdr_section->getPrevious() == nullptr) &&
+        (shdr[i]->sh_offset > ehdr->e_shoff)) {
+      shdr_section->insertAfter(sections[i - 1], false);
+      sections[i]->insertAfter(shdr_section, false);
+    } else
+      sections[i]->insertAfter(sections[i - 1], false);
+  }
+  if (shdr_section->getPrevious() == nullptr)
+    shdr_section->insertAfter(sections[ehdr->e_shnum - 1], false);
+
+  tmp_file = nullptr;
+  tmp_shdr = nullptr;
+  for (int i = 0; i < ehdr->e_shnum; i++) delete shdr[i];
+  delete[] shdr;
+
+  eh_shstrndx = (ElfStrtab_Section*)sections[ehdr->e_shstrndx];
+
+  // Skip reading program headers if there aren't any
+  if (ehdr->e_phnum == 0) return;
+
+  bool adjusted_phdr_section = false;
+  // Read program headers
+  file.seekg(ehdr->e_phoff);
+  for (int i = 0; i < ehdr->e_phnum; i++) {
+    Elf_Phdr phdr(file, e_ident[EI_CLASS], e_ident[EI_DATA]);
+    if (phdr.p_type == PT_LOAD) {
+      // Default alignment for PT_LOAD on x86-64 prevents elfhack from
+      // doing anything useful. However, the system doesn't actually
+      // require such a big alignment, so in order for elfhack to work
+      // efficiently, reduce alignment when it's originally the default
+      // one.
+      if ((ehdr->e_machine == EM_X86_64) && (phdr.p_align == 0x200000))
+        phdr.p_align = 0x1000;
+    }
+    ElfSegment* segment = new ElfSegment(&phdr);
+    // Some segments aren't entirely filled (if at all) by sections
+    // For those, we use fake sections
+    if ((phdr.p_type == PT_LOAD) && (phdr.p_offset == 0)) {
+      // Use a fake section for ehdr and phdr
+      ehdr->getShdr().sh_addr = phdr.p_vaddr;
+      if (!adjusted_phdr_section) {
+        phdr_section->getShdr().sh_addr += phdr.p_vaddr;
+        adjusted_phdr_section = true;
+      }
+      segment->addSection(ehdr);
+      segment->addSection(phdr_section);
+    }
+    if (phdr.p_type == PT_PHDR) {
+      if (!adjusted_phdr_section) {
+        phdr_section->getShdr().sh_addr = phdr.p_vaddr;
+        adjusted_phdr_section = true;
+      }
+      segment->addSection(phdr_section);
+    }
+    for (int j = 1; j < ehdr->e_shnum; j++)
+      if (phdr.contains(sections[j])) segment->addSection(sections[j]);
+    // Make sure that our view of segments corresponds to the original
+    // ELF file.
+    // GNU gold likes to start some segments before the first section
+    // they contain. https://sourceware.org/bugzilla/show_bug.cgi?id=19392
+    unsigned int gold_adjustment = segment->getAddr() - phdr.p_vaddr;
+    assert(segment->getFileSize() == phdr.p_filesz - gold_adjustment);
+    // gold makes TLS segments end on an aligned virtual address, even
+    // when the underlying section ends before that, while bfd ld
+    // doesn't. It's fine if we don't keep that alignment.
+    unsigned int memsize = segment->getMemSize();
+    if (phdr.p_type == PT_TLS && memsize != phdr.p_memsz) {
+      unsigned int align = segment->getAlign();
+      memsize = (memsize + align - 1) & ~(align - 1);
+    }
+    assert(memsize == phdr.p_memsz - gold_adjustment);
+    segments.push_back(segment);
+  }
+
+  new (&eh_entry) ElfLocation(ehdr->e_entry, this);
+}
+
+Elf::~Elf() {
+  for (std::vector<ElfSegment*>::iterator seg = segments.begin();
+       seg != segments.end(); seg++)
+    delete *seg;
+  delete[] sections;
+  ElfSection* section = ehdr;
+  while (section != nullptr) {
+    ElfSection* next = section->getNext();
+    delete section;
+    section = next;
+  }
+}
+
+// TODO: This shouldn't fail after inserting sections
+ElfSection* Elf::getSection(int index) {
+  if ((index < -1) || (index >= ehdr->e_shnum))
+    throw std::runtime_error("Section index out of bounds");
+  if (index == -1)
+    index = ehdr->e_shstrndx;  // TODO: should be fixed to use the actual
+                               // current number
+  // Special case: the section at index 0 is void
+  if (index == 0) return nullptr;
+  // Infinite recursion guard
+  if (sections[index] == (ElfSection*)this) return nullptr;
+  if (sections[index] == nullptr) {
+    sections[index] = (ElfSection*)this;
+    switch (tmp_shdr[index]->sh_type) {
+      case SHT_DYNAMIC:
+        sections[index] =
+            new ElfDynamic_Section(*tmp_shdr[index], tmp_file, this);
+        break;
+      case SHT_REL:
+        sections[index] =
+            new ElfRel_Section<Elf_Rel>(*tmp_shdr[index], tmp_file, this);
+        break;
+      case SHT_RELA:
+        sections[index] =
+            new ElfRel_Section<Elf_Rela>(*tmp_shdr[index], tmp_file, this);
+        break;
+      case SHT_DYNSYM:
+      case SHT_SYMTAB:
+        sections[index] =
+            new ElfSymtab_Section(*tmp_shdr[index], tmp_file, this);
+        break;
+      case SHT_STRTAB:
+        sections[index] =
+            new ElfStrtab_Section(*tmp_shdr[index], tmp_file, this);
+        break;
+      default:
+        sections[index] = new ElfSection(*tmp_shdr[index], tmp_file, this);
+    }
+  }
+  return sections[index];
+}
+
+ElfSection* Elf::getSectionAt(Elf64_Off offset) {
+  for (int i = 1; i < ehdr->e_shnum; i++) {
+    ElfSection* section = getSection(i);
+    if ((section != nullptr) && (section->getFlags() & SHF_ALLOC) &&
+        !(section->getFlags() & SHF_TLS) && (offset >= section->getAddr()) &&
+        (offset < section->getAddr() + section->getSize()))
+      return section;
+  }
+  return nullptr;
+}
+
+ElfSegment* Elf::getSegmentByType(unsigned int type, ElfSegment* last) {
+  std::vector<ElfSegment*>::iterator seg;
+  if (last) {
+    seg = std::find(segments.begin(), segments.end(), last);
+    ++seg;
+  } else
+    seg = segments.begin();
+  for (; seg != segments.end(); seg++)
+    if ((*seg)->getType() == type) return *seg;
+  return nullptr;
+}
+
+void Elf::removeSegment(ElfSegment* segment) {
+  if (!segment) return;
+  std::vector<ElfSegment*>::iterator seg;
+  seg = std::find(segments.begin(), segments.end(), segment);
+  if (seg == segments.end()) return;
+  segment->clear();
+  segments.erase(seg);
+}
+
+ElfDynamic_Section* Elf::getDynSection() {
+  for (std::vector<ElfSegment*>::iterator seg = segments.begin();
+       seg != segments.end(); seg++)
+    if (((*seg)->getType() == PT_DYNAMIC) &&
+        ((*seg)->getFirstSection() != nullptr) &&
+        (*seg)->getFirstSection()->getType() == SHT_DYNAMIC)
+      return (ElfDynamic_Section*)(*seg)->getFirstSection();
+
+  return nullptr;
+}
+
+void Elf::normalize() {
+  // fixup section headers sh_name; TODO: that should be done by sections
+  // themselves
+  for (ElfSection* section = ehdr; section != nullptr;
+       section = section->getNext()) {
+    if (section->getIndex() == 0)
+      continue;
+    else
+      ehdr->e_shnum = section->getIndex() + 1;
+    section->getShdr().sh_name = eh_shstrndx->getStrIndex(section->getName());
+  }
+  ehdr->markDirty();
+  // Check segments consistency
+  int i = 0;
+  for (std::vector<ElfSegment*>::iterator seg = segments.begin();
+       seg != segments.end(); seg++, i++) {
+    std::list<ElfSection*>::iterator it = (*seg)->begin();
+    for (ElfSection* last = *(it++); it != (*seg)->end(); last = *(it++)) {
+      if (((*it)->getType() != SHT_NOBITS) &&
+          ((*it)->getAddr() - last->getAddr()) !=
+              ((*it)->getOffset() - last->getOffset())) {
+        throw std::runtime_error("Segments inconsistency");
+      }
+    }
+  }
+
+  ElfSegment* prevLoad = nullptr;
+  for (auto& it : segments) {
+    if (it->getType() == PT_LOAD) {
+      if (prevLoad) {
+        size_t alignedPrevEnd = (prevLoad->getAddr() + prevLoad->getMemSize() +
+                                 prevLoad->getAlign() - 1) &
+                                ~(prevLoad->getAlign() - 1);
+        size_t alignedStart = it->getAddr() & ~(it->getAlign() - 1);
+        if (alignedPrevEnd > alignedStart) {
+          throw std::runtime_error("Segments overlap");
+        }
+      }
+      prevLoad = it;
+    }
+  }
+
+  // fixup ehdr before writing
+  if (ehdr->e_phnum != segments.size()) {
+    ehdr->e_phnum = segments.size();
+    phdr_section->getShdr().sh_size =
+        segments.size() * Elf_Phdr::size(ehdr->e_ident[EI_CLASS]);
+    phdr_section->getNext()->markDirty();
+  }
+  // fixup shdr before writing
+  if (ehdr->e_shnum != shdr_section->getSize() / shdr_section->getEntSize())
+    shdr_section->getShdr().sh_size =
+        ehdr->e_shnum * Elf_Shdr::size(ehdr->e_ident[EI_CLASS]);
+  ehdr->e_shoff = shdr_section->getOffset();
+  ehdr->e_entry = eh_entry.getValue();
+  ehdr->e_shstrndx = eh_shstrndx->getIndex();
+
+  // Check sections consistency
+  unsigned int minOffset = 0;
+  for (ElfSection* section = ehdr; section != nullptr;
+       section = section->getNext()) {
+    unsigned int offset = section->getOffset();
+    if (offset < minOffset) {
+      throw std::runtime_error("Sections overlap");
+    }
+    if (section->getType() != SHT_NOBITS) {
+      minOffset = offset + section->getSize();
+    }
+  }
+}
+
+void Elf::write(std::ofstream& file) {
+  normalize();
+  for (ElfSection* section = ehdr; section != nullptr;
+       section = section->getNext()) {
+    file.seekp(section->getOffset());
+    if (section == phdr_section) {
+      for (std::vector<ElfSegment*>::iterator seg = segments.begin();
+           seg != segments.end(); seg++) {
+        Elf_Phdr phdr;
+        phdr.p_type = (*seg)->getType();
+        phdr.p_flags = (*seg)->getFlags();
+        phdr.p_offset = (*seg)->getOffset();
+        phdr.p_vaddr = (*seg)->getAddr();
+        phdr.p_paddr = phdr.p_vaddr + (*seg)->getVPDiff();
+        phdr.p_filesz = (*seg)->getFileSize();
+        phdr.p_memsz = (*seg)->getMemSize();
+        phdr.p_align = (*seg)->getAlign();
+        phdr.serialize(file, ehdr->e_ident[EI_CLASS], ehdr->e_ident[EI_DATA]);
+      }
+    } else if (section == shdr_section) {
+      null_section.serialize(file, ehdr->e_ident[EI_CLASS],
+                             ehdr->e_ident[EI_DATA]);
+      for (ElfSection* sec = ehdr; sec != nullptr; sec = sec->getNext()) {
+        if (sec->getType() != SHT_NULL)
+          sec->getShdr().serialize(file, ehdr->e_ident[EI_CLASS],
+                                   ehdr->e_ident[EI_DATA]);
+      }
+    } else
+      section->serialize(file, ehdr->e_ident[EI_CLASS], ehdr->e_ident[EI_DATA]);
+  }
+}
+
+ElfSection::ElfSection(Elf_Shdr& s, std::ifstream* file, Elf* parent)
+    : shdr(s),
+      link(shdr.sh_link == SHN_UNDEF ? nullptr
+                                     : parent->getSection(shdr.sh_link)),
+      next(nullptr),
+      previous(nullptr),
+      index(-1) {
+  if ((file == nullptr) || (shdr.sh_type == SHT_NULL) ||
+      (shdr.sh_type == SHT_NOBITS))
+    data = nullptr;
+  else {
+    data = static_cast<char*>(malloc(shdr.sh_size));
+    if (!data) {
+      throw std::runtime_error("Could not malloc ElfSection data");
+    }
+    auto pos = file->tellg();
+    file->seekg(shdr.sh_offset);
+    file->read(data, shdr.sh_size);
+    file->seekg(pos);
+  }
+  if (shdr.sh_name == 0)
+    name = nullptr;
+  else {
+    ElfStrtab_Section* strtab = (ElfStrtab_Section*)parent->getSection(-1);
+    // Special case (see elfgeneric.cpp): if strtab is nullptr, the
+    // section being created is the strtab.
+    if (strtab == nullptr)
+      name = &data[shdr.sh_name];
+    else
+      name = strtab->getStr(shdr.sh_name);
+  }
+  // Only SHT_REL/SHT_RELA sections use sh_info to store a section
+  // number.
+  if ((shdr.sh_type == SHT_REL) || (shdr.sh_type == SHT_RELA))
+    info.section = shdr.sh_info ? parent->getSection(shdr.sh_info) : nullptr;
+  else
+    info.index = shdr.sh_info;
+}
+
+Elf64_Addr ElfSection::getAddr() {
+  if (shdr.sh_addr != (Elf64_Addr)-1) return shdr.sh_addr;
+
+  // It should be safe to adjust sh_addr for all allocated sections that
+  // are neither SHT_NOBITS nor SHT_PROGBITS
+  if ((previous != nullptr) && isRelocatable()) {
+    unsigned int addr = previous->getAddr();
+    if (previous->getType() != SHT_NOBITS) addr += previous->getSize();
+
+    if (addr & (getAddrAlign() - 1)) addr = (addr | (getAddrAlign() - 1)) + 1;
+
+    return (shdr.sh_addr = addr);
+  }
+  return shdr.sh_addr;
+}
+
+Elf64_Off ElfSection::getOffset() {
+  if (shdr.sh_offset != (Elf64_Off)-1) return shdr.sh_offset;
+
+  if (previous == nullptr) return (shdr.sh_offset = 0);
+
+  Elf64_Off offset = previous->getOffset();
+
+  ElfSegment* ptload = getSegmentByType(PT_LOAD);
+  ElfSegment* prev_ptload = previous->getSegmentByType(PT_LOAD);
+
+  if (ptload && (ptload == prev_ptload)) {
+    offset += getAddr() - previous->getAddr();
+    return (shdr.sh_offset = offset);
+  }
+
+  if (previous->getType() != SHT_NOBITS) offset += previous->getSize();
+
+  Elf32_Word align = 0x1000;
+  for (std::vector<ElfSegment*>::iterator seg = segments.begin();
+       seg != segments.end(); seg++)
+    align = std::max(align, (*seg)->getAlign());
+
+  Elf32_Word mask = align - 1;
+  // SHF_TLS is used for .tbss which is some kind of special case.
+  if (((getType() != SHT_NOBITS) || (getFlags() & SHF_TLS)) &&
+      (getFlags() & SHF_ALLOC)) {
+    if ((getAddr() & mask) < (offset & mask))
+      offset = (offset | mask) + (getAddr() & mask) + 1;
+    else
+      offset = (offset & ~mask) + (getAddr() & mask);
+  }
+  if ((getType() != SHT_NOBITS) && (offset & (getAddrAlign() - 1)))
+    offset = (offset | (getAddrAlign() - 1)) + 1;
+
+  return (shdr.sh_offset = offset);
+}
+
+int ElfSection::getIndex() {
+  if (index != -1) return index;
+  if (getType() == SHT_NULL) return (index = 0);
+  ElfSection* reference;
+  for (reference = previous;
+       (reference != nullptr) && (reference->getType() == SHT_NULL);
+       reference = reference->getPrevious())
+    ;
+  if (reference == nullptr) return (index = 1);
+  return (index = reference->getIndex() + 1);
+}
+
+Elf_Shdr& ElfSection::getShdr() {
+  getOffset();
+  if (shdr.sh_link == (Elf64_Word)-1)
+    shdr.sh_link = getLink() ? getLink()->getIndex() : 0;
+  if (shdr.sh_info == (Elf64_Word)-1)
+    shdr.sh_info = ((getType() == SHT_REL) || (getType() == SHT_RELA))
+                       ? (getInfo().section ? getInfo().section->getIndex() : 0)
+                       : getInfo().index;
+
+  return shdr;
+}
+
+ElfSegment::ElfSegment(Elf_Phdr* phdr)
+    : type(phdr->p_type),
+      v_p_diff(phdr->p_paddr - phdr->p_vaddr),
+      flags(phdr->p_flags),
+      align(phdr->p_align),
+      vaddr(phdr->p_vaddr),
+      filesz(phdr->p_filesz),
+      memsz(phdr->p_memsz) {}
+
+void ElfSegment::addSection(ElfSection* section) {
+  // Make sure all sections in PT_GNU_RELRO won't be moved by elfhack
+  assert(!((type == PT_GNU_RELRO) && (section->isRelocatable())));
+
+  // TODO: Check overlapping sections
+  std::list<ElfSection*>::iterator i;
+  for (i = sections.begin(); i != sections.end(); ++i)
+    if ((*i)->getAddr() > section->getAddr()) break;
+  sections.insert(i, section);
+  section->addToSegment(this);
+}
+
+void ElfSegment::removeSection(ElfSection* section) {
+  sections.remove(section);
+  section->removeFromSegment(this);
+}
+
+unsigned int ElfSegment::getFileSize() {
+  if (type == PT_GNU_RELRO) return filesz;
+
+  if (sections.empty()) return 0;
+  // Search the last section that is not SHT_NOBITS
+  std::list<ElfSection*>::reverse_iterator i;
+  for (i = sections.rbegin();
+       (i != sections.rend()) && ((*i)->getType() == SHT_NOBITS); ++i)
+    ;
+  // All sections are SHT_NOBITS
+  if (i == sections.rend()) return 0;
+
+  unsigned int end = (*i)->getAddr() + (*i)->getSize();
+
+  return end - sections.front()->getAddr();
+}
+
+unsigned int ElfSegment::getMemSize() {
+  if (type == PT_GNU_RELRO) return memsz;
+
+  if (sections.empty()) return 0;
+
+  unsigned int end = sections.back()->getAddr() + sections.back()->getSize();
+
+  return end - sections.front()->getAddr();
+}
+
+unsigned int ElfSegment::getOffset() {
+  if ((type == PT_GNU_RELRO) && !sections.empty() &&
+      (sections.front()->getAddr() != vaddr))
+    throw std::runtime_error(
+        "PT_GNU_RELRO segment doesn't start on a section start");
+
+  return sections.empty() ? 0 : sections.front()->getOffset();
+}
+
+unsigned int ElfSegment::getAddr() {
+  if ((type == PT_GNU_RELRO) && !sections.empty() &&
+      (sections.front()->getAddr() != vaddr))
+    throw std::runtime_error(
+        "PT_GNU_RELRO segment doesn't start on a section start");
+
+  return sections.empty() ? 0 : sections.front()->getAddr();
+}
+
+void ElfSegment::clear() {
+  for (std::list<ElfSection*>::iterator i = sections.begin();
+       i != sections.end(); ++i)
+    (*i)->removeFromSegment(this);
+  sections.clear();
+}
+
+ElfValue* ElfDynamic_Section::getValueForType(unsigned int tag) {
+  for (unsigned int i = 0; i < shdr.sh_size / shdr.sh_entsize; i++)
+    if (dyns[i].tag == tag) return dyns[i].value;
+
+  return nullptr;
+}
+
+ElfSection* ElfDynamic_Section::getSectionForType(unsigned int tag) {
+  ElfValue* value = getValueForType(tag);
+  return value ? value->getSection() : nullptr;
+}
+
+bool ElfDynamic_Section::setValueForType(unsigned int tag, ElfValue* val) {
+  unsigned int i;
+  unsigned int shnum = shdr.sh_size / shdr.sh_entsize;
+  for (i = 0; (i < shnum) && (dyns[i].tag != DT_NULL); i++)
+    if (dyns[i].tag == tag) {
+      delete dyns[i].value;
+      dyns[i].value = val;
+      return true;
+    }
+  // If we get here, this means we didn't match for the given tag
+  // Most of the time, there are a few DT_NULL entries, that we can
+  // use to add our value, but if we are on the last entry, we can't.
+  if (i >= shnum - 1) return false;
+
+  dyns[i].tag = tag;
+  dyns[i].value = val;
+  return true;
+}
+
+ElfDynamic_Section::ElfDynamic_Section(Elf_Shdr& s, std::ifstream* file,
+                                       Elf* parent)
+    : ElfSection(s, file, parent) {
+  auto pos = file->tellg();
+  dyns.resize(s.sh_size / s.sh_entsize);
+  file->seekg(shdr.sh_offset);
+  // Here we assume tags refer to only one section (e.g. DT_RELSZ accounts
+  // for .rel.dyn size)
+  for (unsigned int i = 0; i < s.sh_size / s.sh_entsize; i++) {
+    Elf_Dyn dyn(*file, parent->getClass(), parent->getData());
+    dyns[i].tag = dyn.d_tag;
+    switch (dyn.d_tag) {
+      case DT_NULL:
+      case DT_SYMBOLIC:
+      case DT_TEXTREL:
+      case DT_BIND_NOW:
+        dyns[i].value = new ElfValue();
+        break;
+      case DT_NEEDED:
+      case DT_SONAME:
+      case DT_RPATH:
+      case DT_PLTREL:
+      case DT_RUNPATH:
+      case DT_FLAGS:
+      case DT_RELACOUNT:
+      case DT_RELCOUNT:
+      case DT_VERDEFNUM:
+      case DT_VERNEEDNUM:
+        dyns[i].value = new ElfPlainValue(dyn.d_un.d_val);
+        break;
+      case DT_PLTGOT:
+      case DT_HASH:
+      case DT_STRTAB:
+      case DT_SYMTAB:
+      case DT_RELA:
+      case DT_INIT:
+      case DT_FINI:
+      case DT_REL:
+      case DT_JMPREL:
+      case DT_INIT_ARRAY:
+      case DT_FINI_ARRAY:
+      case DT_GNU_HASH:
+      case DT_VERSYM:
+      case DT_VERNEED:
+      case DT_VERDEF:
+        dyns[i].value = new ElfLocation(dyn.d_un.d_ptr, parent);
+        break;
+      default:
+        dyns[i].value = nullptr;
+    }
+  }
+  // Another loop to get the section sizes
+  for (unsigned int i = 0; i < s.sh_size / s.sh_entsize; i++)
+    switch (dyns[i].tag) {
+      case DT_PLTRELSZ:
+        dyns[i].value = new ElfSize(getSectionForType(DT_JMPREL));
+        break;
+      case DT_RELASZ:
+        dyns[i].value = new ElfSize(getSectionForType(DT_RELA));
+        break;
+      case DT_STRSZ:
+        dyns[i].value = new ElfSize(getSectionForType(DT_STRTAB));
+        break;
+      case DT_RELSZ:
+        dyns[i].value = new ElfSize(getSectionForType(DT_REL));
+        break;
+      case DT_INIT_ARRAYSZ:
+        dyns[i].value = new ElfSize(getSectionForType(DT_INIT_ARRAY));
+        break;
+      case DT_FINI_ARRAYSZ:
+        dyns[i].value = new ElfSize(getSectionForType(DT_FINI_ARRAY));
+        break;
+      case DT_RELAENT:
+        dyns[i].value = new ElfEntSize(getSectionForType(DT_RELA));
+        break;
+      case DT_SYMENT:
+        dyns[i].value = new ElfEntSize(getSectionForType(DT_SYMTAB));
+        break;
+      case DT_RELENT:
+        dyns[i].value = new ElfEntSize(getSectionForType(DT_REL));
+        break;
+    }
+
+  file->seekg(pos);
+}
+
+ElfDynamic_Section::~ElfDynamic_Section() {
+  for (unsigned int i = 0; i < shdr.sh_size / shdr.sh_entsize; i++)
+    delete dyns[i].value;
+}
+
+void ElfDynamic_Section::serialize(std::ofstream& file, unsigned char ei_class,
+                                   unsigned char ei_data) {
+  for (unsigned int i = 0; i < shdr.sh_size / shdr.sh_entsize; i++) {
+    Elf_Dyn dyn;
+    dyn.d_tag = dyns[i].tag;
+    dyn.d_un.d_val = (dyns[i].value != nullptr) ? dyns[i].value->getValue() : 0;
+    dyn.serialize(file, ei_class, ei_data);
+  }
+}
+
+ElfSymtab_Section::ElfSymtab_Section(Elf_Shdr& s, std::ifstream* file,
+                                     Elf* parent)
+    : ElfSection(s, file, parent) {
+  auto pos = file->tellg();
+  syms.resize(s.sh_size / s.sh_entsize);
+  ElfStrtab_Section* strtab = (ElfStrtab_Section*)getLink();
+  file->seekg(shdr.sh_offset);
+  for (unsigned int i = 0; i < shdr.sh_size / shdr.sh_entsize; i++) {
+    Elf_Sym sym(*file, parent->getClass(), parent->getData());
+    syms[i].name = strtab->getStr(sym.st_name);
+    syms[i].info = sym.st_info;
+    syms[i].other = sym.st_other;
+    ElfSection* section =
+        (sym.st_shndx == SHN_ABS) ? nullptr : parent->getSection(sym.st_shndx);
+    new (&syms[i].value)
+        ElfLocation(section, sym.st_value, ElfLocation::ABSOLUTE);
+    syms[i].size = sym.st_size;
+    syms[i].defined = (sym.st_shndx != SHN_UNDEF);
+  }
+  file->seekg(pos);
+}
+
+void ElfSymtab_Section::serialize(std::ofstream& file, unsigned char ei_class,
+                                  unsigned char ei_data) {
+  ElfStrtab_Section* strtab = (ElfStrtab_Section*)getLink();
+  for (unsigned int i = 0; i < shdr.sh_size / shdr.sh_entsize; i++) {
+    Elf_Sym sym;
+    sym.st_name = strtab->getStrIndex(syms[i].name);
+    sym.st_info = syms[i].info;
+    sym.st_other = syms[i].other;
+    sym.st_value = syms[i].value.getValue();
+    ElfSection* section = syms[i].value.getSection();
+    if (syms[i].defined)
+      sym.st_shndx = section ? section->getIndex() : SHN_ABS;
+    else
+      sym.st_shndx = SHN_UNDEF;
+    sym.st_size = syms[i].size;
+    sym.serialize(file, ei_class, ei_data);
+  }
+}
+
+Elf_SymValue* ElfSymtab_Section::lookup(const char* name,
+                                        unsigned int type_filter) {
+  for (std::vector<Elf_SymValue>::iterator sym = syms.begin();
+       sym != syms.end(); sym++) {
+    if ((type_filter & (1 << ELF32_ST_TYPE(sym->info))) &&
+        (strcmp(sym->name, name) == 0)) {
+      return &*sym;
+    }
+  }
+  return nullptr;
+}
+
+const char* ElfStrtab_Section::getStr(unsigned int index) {
+  for (std::vector<table_storage>::iterator t = table.begin(); t != table.end();
+       t++) {
+    if (index < t->used) return t->buf + index;
+    index -= t->used;
+  }
+  assert(1 == 0);
+  return nullptr;
+}
+
+const char* ElfStrtab_Section::getStr(const char* string) {
+  if (string == nullptr) return nullptr;
+
+  // If the given string is within the section, return it
+  for (std::vector<table_storage>::iterator t = table.begin(); t != table.end();
+       t++)
+    if ((string >= t->buf) && (string < t->buf + t->used)) return string;
+
+  // TODO: should scan in the section to find an existing string
+
+  // If not, we need to allocate the string in the section
+  size_t len = strlen(string) + 1;
+
+  if (table.back().size - table.back().used < len)
+    table.resize(table.size() + 1);
+
+  char* alloc_str = table.back().buf + table.back().used;
+  memcpy(alloc_str, string, len);
+  table.back().used += len;
+
+  shdr.sh_size += len;
+  markDirty();
+
+  return alloc_str;
+}
+
+unsigned int ElfStrtab_Section::getStrIndex(const char* string) {
+  if (string == nullptr) return 0;
+
+  unsigned int index = 0;
+  string = getStr(string);
+  for (std::vector<table_storage>::iterator t = table.begin(); t != table.end();
+       t++) {
+    if ((string >= t->buf) && (string < t->buf + t->used))
+      return index + (string - t->buf);
+    index += t->used;
+  }
+
+  assert(1 == 0);
+  return 0;
+}
+
+void ElfStrtab_Section::serialize(std::ofstream& file, unsigned char ei_class,
+                                  unsigned char ei_data) {
+  file.seekp(getOffset());
+  for (std::vector<table_storage>::iterator t = table.begin(); t != table.end();
+       t++)
+    file.write(t->buf, t->used);
+}