1 files changed, 1360 insertions, 0 deletions
diff --git a/externals/breakpad/src/common/linux/dump_symbols.cc b/externals/breakpad/src/common/linux/dump_symbols.cc
new file mode 100644
index 0000000000..b693fc9e16
--- /dev/null
+++ b/externals/breakpad/src/common/linux/dump_symbols.cc
@@ -0,0 +1,1360 @@
+// Copyright 2011 Google LLC
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google LLC nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Restructured in 2009 by: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// dump_symbols.cc: implement google_breakpad::WriteSymbolFile:
+// Find all the debugging info in a file and dump it as a Breakpad symbol file.
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>  // Must come first
+#endif
+
+#include "common/linux/dump_symbols.h"
+
+#include <assert.h>
+#include <elf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <link.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <zlib.h>
+#ifdef HAVE_LIBZSTD
+#include <zstd.h>
+#endif
+
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "common/dwarf/bytereader-inl.h"
+#include "common/dwarf/dwarf2diehandler.h"
+#include "common/dwarf_cfi_to_module.h"
+#include "common/dwarf_cu_to_module.h"
+#include "common/dwarf_line_to_module.h"
+#include "common/dwarf_range_list_handler.h"
+#include "common/linux/crc32.h"
+#include "common/linux/eintr_wrapper.h"
+#include "common/linux/elfutils.h"
+#include "common/linux/elfutils-inl.h"
+#include "common/linux/elf_symbols_to_module.h"
+#include "common/linux/file_id.h"
+#include "common/memory_allocator.h"
+#include "common/module.h"
+#include "common/path_helper.h"
+#include "common/scoped_ptr.h"
+#ifndef NO_STABS_SUPPORT
+#include "common/stabs_reader.h"
+#include "common/stabs_to_module.h"
+#endif
+#include "common/using_std_string.h"
+
+// This namespace contains helper functions.
+namespace {
+
+using google_breakpad::DumpOptions;
+using google_breakpad::DwarfCFIToModule;
+using google_breakpad::DwarfCUToModule;
+using google_breakpad::DwarfLineToModule;
+using google_breakpad::DwarfRangeListHandler;
+using google_breakpad::ElfClass;
+using google_breakpad::ElfClass32;
+using google_breakpad::ElfClass64;
+using google_breakpad::elf::FileID;
+using google_breakpad::FindElfSectionByName;
+using google_breakpad::GetOffset;
+using google_breakpad::IsValidElf;
+using google_breakpad::elf::kDefaultBuildIdSize;
+using google_breakpad::Module;
+using google_breakpad::PageAllocator;
+#ifndef NO_STABS_SUPPORT
+using google_breakpad::StabsToModule;
+#endif
+using google_breakpad::scoped_ptr;
+using google_breakpad::wasteful_vector;
+
+// Define AARCH64 ELF architecture if host machine does not include this define.
+#ifndef EM_AARCH64
+#define EM_AARCH64      183
+#endif
+
+// Define ZStd compression if host machine does not include this define.
+#ifndef ELFCOMPRESS_ZSTD
+#define ELFCOMPRESS_ZSTD 2
+#endif
+
+//
+// FDWrapper
+//
+// Wrapper class to make sure opened file is closed.
+//
+class FDWrapper {
+ public:
+  explicit FDWrapper(int fd) :
+    fd_(fd) {}
+  ~FDWrapper() {
+    if (fd_ != -1)
+      close(fd_);
+  }
+  int get() {
+    return fd_;
+  }
+  int release() {
+    int fd = fd_;
+    fd_ = -1;
+    return fd;
+  }
+ private:
+  int fd_;
+};
+
+//
+// MmapWrapper
+//
+// Wrapper class to make sure mapped regions are unmapped.
+//
+class MmapWrapper {
+ public:
+  MmapWrapper() : is_set_(false) {}
+  ~MmapWrapper() {
+    if (is_set_ && base_ != NULL) {
+      assert(size_ > 0);
+      munmap(base_, size_);
+    }
+  }
+  void set(void* mapped_address, size_t mapped_size) {
+    is_set_ = true;
+    base_ = mapped_address;
+    size_ = mapped_size;
+  }
+  void release() {
+    assert(is_set_);
+    is_set_ = false;
+    base_ = NULL;
+    size_ = 0;
+  }
+
+ private:
+  bool is_set_;
+  void* base_;
+  size_t size_;
+};
+
+// Find the preferred loading address of the binary.
+template<typename ElfClass>
+typename ElfClass::Addr GetLoadingAddress(
+    const typename ElfClass::Phdr* program_headers,
+    int nheader) {
+  typedef typename ElfClass::Phdr Phdr;
+
+  // For non-PIC executables (e_type == ET_EXEC), the load address is
+  // the start address of the first PT_LOAD segment.  (ELF requires
+  // the segments to be sorted by load address.)  For PIC executables
+  // and dynamic libraries (e_type == ET_DYN), this address will
+  // normally be zero.
+  for (int i = 0; i < nheader; ++i) {
+    const Phdr& header = program_headers[i];
+    if (header.p_type == PT_LOAD)
+      return header.p_vaddr;
+  }
+  return 0;
+}
+
+// Find the set of address ranges for all PT_LOAD segments.
+template <typename ElfClass>
+vector<Module::Range> GetPtLoadSegmentRanges(
+    const typename ElfClass::Phdr* program_headers,
+    int nheader) {
+  typedef typename ElfClass::Phdr Phdr;
+  vector<Module::Range> ranges;
+
+  for (int i = 0; i < nheader; ++i) {
+    const Phdr& header = program_headers[i];
+    if (header.p_type == PT_LOAD) {
+      ranges.push_back(Module::Range(header.p_vaddr, header.p_memsz));
+    }
+  }
+  return ranges;
+}
+
+#ifndef NO_STABS_SUPPORT
+template<typename ElfClass>
+bool LoadStabs(const typename ElfClass::Ehdr* elf_header,
+               const typename ElfClass::Shdr* stab_section,
+               const typename ElfClass::Shdr* stabstr_section,
+               const bool big_endian,
+               Module* module) {
+  // A callback object to handle data from the STABS reader.
+  StabsToModule handler(module);
+  // Find the addresses of the STABS data, and create a STABS reader object.
+  // On Linux, STABS entries always have 32-bit values, regardless of the
+  // address size of the architecture whose code they're describing, and
+  // the strings are always "unitized".
+  const uint8_t* stabs =
+      GetOffset<ElfClass, uint8_t>(elf_header, stab_section->sh_offset);
+  const uint8_t* stabstr =
+      GetOffset<ElfClass, uint8_t>(elf_header, stabstr_section->sh_offset);
+  google_breakpad::StabsReader reader(stabs, stab_section->sh_size,
+                                      stabstr, stabstr_section->sh_size,
+                                      big_endian, 4, true, &handler);
+  // Read the STABS data, and do post-processing.
+  if (!reader.Process())
+    return false;
+  handler.Finalize();
+  return true;
+}
+#endif  // NO_STABS_SUPPORT
+
+// A range handler that accepts rangelist data parsed by
+// google_breakpad::RangeListReader and populates a range vector (typically
+// owned by a function) with the results.
+class DumperRangesHandler : public DwarfCUToModule::RangesHandler {
+ public:
+  DumperRangesHandler(google_breakpad::ByteReader* reader) :
+      reader_(reader) { }
+
+  bool ReadRanges(
+      enum google_breakpad::DwarfForm form, uint64_t data,
+      google_breakpad::RangeListReader::CURangesInfo* cu_info,
+      vector<Module::Range>* ranges) {
+    DwarfRangeListHandler handler(ranges);
+    google_breakpad::RangeListReader range_list_reader(reader_, cu_info,
+                                                    &handler);
+    return range_list_reader.ReadRanges(form, data);
+  }
+
+ private:
+  google_breakpad::ByteReader* reader_;
+};
+
+// A line-to-module loader that accepts line number info parsed by
+// google_breakpad::LineInfo and populates a Module and a line vector
+// with the results.
+class DumperLineToModule: public DwarfCUToModule::LineToModuleHandler {
+ public:
+  // Create a line-to-module converter using BYTE_READER.
+  explicit DumperLineToModule(google_breakpad::ByteReader* byte_reader)
+      : byte_reader_(byte_reader) { }
+  void StartCompilationUnit(const string& compilation_dir) {
+    compilation_dir_ = compilation_dir;
+  }
+  void ReadProgram(const uint8_t* program,
+                   uint64_t length,
+                   const uint8_t* string_section,
+                   uint64_t string_section_length,
+                   const uint8_t* line_string_section,
+                   uint64_t line_string_section_length,
+                   Module* module,
+                   std::vector<Module::Line>* lines,
+                   std::map<uint32_t, Module::File*>* files) {
+    DwarfLineToModule handler(module, compilation_dir_, lines, files);
+    google_breakpad::LineInfo parser(program, length, byte_reader_,
+                                  string_section, string_section_length,
+                                  line_string_section,
+                                  line_string_section_length,
+                                  &handler);
+    parser.Start();
+  }
+ private:
+  string compilation_dir_;
+  google_breakpad::ByteReader* byte_reader_;
+};
+
+template<typename ElfClass>
+bool IsCompressedHeader(const typename ElfClass::Shdr* section) {
+  return (section->sh_flags & SHF_COMPRESSED) != 0;
+}
+
+template<typename ElfClass>
+uint32_t GetCompressionHeader(
+    typename ElfClass::Chdr& compression_header,
+    const uint8_t* content, uint64_t size) {
+  const typename ElfClass::Chdr* header =
+      reinterpret_cast<const typename ElfClass::Chdr *>(content);
+
+  if (size < sizeof (*header)) {
+    return 0;
+  }
+
+  compression_header = *header;
+  return sizeof (*header);
+}
+
+std::pair<uint8_t *, uint64_t> UncompressZlibSectionContents(
+    const uint8_t* compressed_buffer, uint64_t compressed_size, uint64_t uncompressed_size) {
+  z_stream stream;
+  memset(&stream, 0, sizeof stream);
+
+  stream.avail_in = compressed_size;
+  stream.avail_out = uncompressed_size;
+  stream.next_in = const_cast<uint8_t *>(compressed_buffer);
+
+  google_breakpad::scoped_array<uint8_t> uncompressed_buffer(
+    new uint8_t[uncompressed_size]);
+
+  int status = inflateInit(&stream);
+  while (stream.avail_in != 0 && status == Z_OK) {
+    stream.next_out =
+      uncompressed_buffer.get() + uncompressed_size - stream.avail_out;
+
+    if ((status = inflate(&stream, Z_FINISH)) != Z_STREAM_END) {
+      break;
+    }
+
+    status = inflateReset(&stream);
+  }
+
+  return inflateEnd(&stream) != Z_OK || status != Z_OK || stream.avail_out != 0
+    ? std::make_pair(nullptr, 0)
+    : std::make_pair(uncompressed_buffer.release(), uncompressed_size);
+}
+
+#ifdef HAVE_LIBZSTD
+std::pair<uint8_t *, uint64_t> UncompressZstdSectionContents(
+    const uint8_t* compressed_buffer, uint64_t compressed_size,uint64_t uncompressed_size) {
+
+  google_breakpad::scoped_array<uint8_t> uncompressed_buffer(new uint8_t[uncompressed_size]);
+  size_t out_size = ZSTD_decompress(uncompressed_buffer.get(), uncompressed_size,
+    compressed_buffer, compressed_size);
+  if (ZSTD_isError(out_size)) {
+    return std::make_pair(nullptr, 0);
+  }
+  assert(out_size == uncompressed_size);
+  return std::make_pair(uncompressed_buffer.release(), uncompressed_size);
+}
+#endif
+
+std::pair<uint8_t *, uint64_t> UncompressSectionContents(
+    uint64_t compression_type, const uint8_t* compressed_buffer,
+    uint64_t compressed_size, uint64_t uncompressed_size) {
+  if (compression_type == ELFCOMPRESS_ZLIB) {
+    return UncompressZlibSectionContents(compressed_buffer, compressed_size, uncompressed_size);
+  }
+
+#ifdef HAVE_LIBZSTD
+  if (compression_type == ELFCOMPRESS_ZSTD) {
+    return UncompressZstdSectionContents(compressed_buffer, compressed_size, uncompressed_size);
+  }
+#endif
+
+  return std::make_pair(nullptr, 0);
+}
+
+void StartProcessSplitDwarf(google_breakpad::CompilationUnit* reader,
+                            Module* module,
+                            google_breakpad::Endianness endianness,
+                            bool handle_inter_cu_refs,
+                            bool handle_inline) {
+  std::string split_file;
+  google_breakpad::SectionMap split_sections;
+  google_breakpad::ByteReader split_byte_reader(endianness);
+  uint64_t cu_offset = 0;
+  if (!reader->ProcessSplitDwarf(split_file, split_sections, split_byte_reader,
+                                 cu_offset))
+    return;
+  DwarfCUToModule::FileContext file_context(split_file, module,
+                                            handle_inter_cu_refs);
+  for (auto section : split_sections)
+    file_context.AddSectionToSectionMap(section.first, section.second.first,
+                                        section.second.second);
+  // Because DWP/DWO file doesn't have .debug_addr/.debug_line/.debug_line_str,
+  // its debug info will refer to .debug_addr/.debug_line in the main binary.
+  if (file_context.section_map().find(".debug_addr") ==
+      file_context.section_map().end())
+    file_context.AddSectionToSectionMap(".debug_addr", reader->GetAddrBuffer(),
+                                        reader->GetAddrBufferLen());
+  if (file_context.section_map().find(".debug_line") ==
+      file_context.section_map().end())
+    file_context.AddSectionToSectionMap(".debug_line", reader->GetLineBuffer(),
+                                        reader->GetLineBufferLen());
+  if (file_context.section_map().find(".debug_line_str") ==
+      file_context.section_map().end())
+    file_context.AddSectionToSectionMap(".debug_line_str",
+                                        reader->GetLineStrBuffer(),
+                                        reader->GetLineStrBufferLen());
+
+  DumperRangesHandler ranges_handler(&split_byte_reader);
+  DumperLineToModule line_to_module(&split_byte_reader);
+  DwarfCUToModule::WarningReporter reporter(split_file, cu_offset);
+  DwarfCUToModule root_handler(
+      &file_context, &line_to_module, &ranges_handler, &reporter, handle_inline,
+      reader->GetLowPC(), reader->GetAddrBase(), reader->HasSourceLineInfo(),
+      reader->GetSourceLineOffset());
+  google_breakpad::DIEDispatcher die_dispatcher(&root_handler);
+  google_breakpad::CompilationUnit split_reader(
+      split_file, file_context.section_map(), cu_offset, &split_byte_reader,
+      &die_dispatcher);
+  split_reader.SetSplitDwarf(reader->GetAddrBase(), reader->GetDWOID());
+  split_reader.Start();
+  // Normally, it won't happen unless we have transitive reference.
+  if (split_reader.ShouldProcessSplitDwarf()) {
+    StartProcessSplitDwarf(&split_reader, module, endianness,
+                           handle_inter_cu_refs, handle_inline);
+  }
+}
+
+template<typename ElfClass>
+bool LoadDwarf(const string& dwarf_filename,
+               const typename ElfClass::Ehdr* elf_header,
+               const bool big_endian,
+               bool handle_inter_cu_refs,
+               bool handle_inline,
+               Module* module) {
+  typedef typename ElfClass::Shdr Shdr;
+
+  const google_breakpad::Endianness endianness = big_endian ?
+      google_breakpad::ENDIANNESS_BIG : google_breakpad::ENDIANNESS_LITTLE;
+  google_breakpad::ByteReader byte_reader(endianness);
+
+  // Construct a context for this file.
+  DwarfCUToModule::FileContext file_context(dwarf_filename,
+                                            module,
+                                            handle_inter_cu_refs);
+
+  // Build a map of the ELF file's sections.
+  const Shdr* sections =
+      GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff);
+  int num_sections = elf_header->e_shnum;
+  const Shdr* section_names = sections + elf_header->e_shstrndx;
+  for (int i = 0; i < num_sections; i++) {
+    const Shdr* section = &sections[i];
+    string name = GetOffset<ElfClass, char>(elf_header,
+                                            section_names->sh_offset) +
+                  section->sh_name;
+    const uint8_t* contents = GetOffset<ElfClass, uint8_t>(elf_header,
+                                                           section->sh_offset);
+    uint64_t size = section->sh_size;
+
+    if (!IsCompressedHeader<ElfClass>(section)) {
+      file_context.AddSectionToSectionMap(name, contents, size);
+      continue;
+    }
+
+    typename ElfClass::Chdr chdr;
+
+    uint32_t compression_header_size =
+      GetCompressionHeader<ElfClass>(chdr, contents, size);
+
+    if (compression_header_size == 0 || chdr.ch_size == 0) {
+      continue;
+    }
+
+    contents += compression_header_size;
+    size -= compression_header_size;
+
+    std::pair<uint8_t *, uint64_t> uncompressed =
+      UncompressSectionContents(chdr.ch_type, contents, size, chdr.ch_size);
+
+    if (uncompressed.first != nullptr && uncompressed.second != 0) {
+      file_context.AddManagedSectionToSectionMap(name, uncompressed.first, uncompressed.second);
+    }
+  }
+
+  // .debug_ranges and .debug_rnglists reader
+  DumperRangesHandler ranges_handler(&byte_reader);
+
+  // Parse all the compilation units in the .debug_info section.
+  DumperLineToModule line_to_module(&byte_reader);
+  google_breakpad::SectionMap::const_iterator debug_info_entry =
+      file_context.section_map().find(".debug_info");
+  assert(debug_info_entry != file_context.section_map().end());
+  const std::pair<const uint8_t*, uint64_t>& debug_info_section =
+      debug_info_entry->second;
+  // This should never have been called if the file doesn't have a
+  // .debug_info section.
+  assert(debug_info_section.first);
+  uint64_t debug_info_length = debug_info_section.second;
+  for (uint64_t offset = 0; offset < debug_info_length;) {
+    // Make a handler for the root DIE that populates MODULE with the
+    // data that was found.
+    DwarfCUToModule::WarningReporter reporter(dwarf_filename, offset);
+    DwarfCUToModule root_handler(&file_context, &line_to_module,
+                                 &ranges_handler, &reporter, handle_inline);
+    // Make a Dwarf2Handler that drives the DIEHandler.
+    google_breakpad::DIEDispatcher die_dispatcher(&root_handler);
+    // Make a DWARF parser for the compilation unit at OFFSET.
+    google_breakpad::CompilationUnit reader(dwarf_filename,
+                                         file_context.section_map(),
+                                         offset,
+                                         &byte_reader,
+                                         &die_dispatcher);
+    // Process the entire compilation unit; get the offset of the next.
+    offset += reader.Start();
+    // Start to process split dwarf file.
+    if (reader.ShouldProcessSplitDwarf()) {
+      StartProcessSplitDwarf(&reader, module, endianness, handle_inter_cu_refs,
+                             handle_inline);
+    }
+  }
+  return true;
+}
+
+// Fill REGISTER_NAMES with the register names appropriate to the
+// machine architecture given in HEADER, indexed by the register
+// numbers used in DWARF call frame information. Return true on
+// success, or false if HEADER's machine architecture is not
+// supported.
+template<typename ElfClass>
+bool DwarfCFIRegisterNames(const typename ElfClass::Ehdr* elf_header,
+                           std::vector<string>* register_names) {
+  switch (elf_header->e_machine) {
+    case EM_386:
+      *register_names = DwarfCFIToModule::RegisterNames::I386();
+      return true;
+    case EM_ARM:
+      *register_names = DwarfCFIToModule::RegisterNames::ARM();
+      return true;
+    case EM_AARCH64:
+      *register_names = DwarfCFIToModule::RegisterNames::ARM64();
+      return true;
+    case EM_MIPS:
+      *register_names = DwarfCFIToModule::RegisterNames::MIPS();
+      return true;
+    case EM_X86_64:
+      *register_names = DwarfCFIToModule::RegisterNames::X86_64();
+      return true;
+    case EM_RISCV:
+      *register_names = DwarfCFIToModule::RegisterNames::RISCV();
+      return true;
+    default:
+      return false;
+  }
+}
+
+template<typename ElfClass>
+bool LoadDwarfCFI(const string& dwarf_filename,
+                  const typename ElfClass::Ehdr* elf_header,
+                  const char* section_name,
+                  const typename ElfClass::Shdr* section,
+                  const bool eh_frame,
+                  const typename ElfClass::Shdr* got_section,
+                  const typename ElfClass::Shdr* text_section,
+                  const bool big_endian,
+                  Module* module) {
+  // Find the appropriate set of register names for this file's
+  // architecture.
+  std::vector<string> register_names;
+  if (!DwarfCFIRegisterNames<ElfClass>(elf_header, &register_names)) {
+    fprintf(stderr, "%s: unrecognized ELF machine architecture '%d';"
+            " cannot convert DWARF call frame information\n",
+            dwarf_filename.c_str(), elf_header->e_machine);
+    return false;
+  }
+
+  const google_breakpad::Endianness endianness = big_endian ?
+      google_breakpad::ENDIANNESS_BIG : google_breakpad::ENDIANNESS_LITTLE;
+
+  // Find the call frame information and its size.
+  const uint8_t* cfi =
+      GetOffset<ElfClass, uint8_t>(elf_header, section->sh_offset);
+  size_t cfi_size = section->sh_size;
+
+  // Plug together the parser, handler, and their entourages.
+  DwarfCFIToModule::Reporter module_reporter(dwarf_filename, section_name);
+  DwarfCFIToModule handler(module, register_names, &module_reporter);
+  google_breakpad::ByteReader byte_reader(endianness);
+
+  byte_reader.SetAddressSize(ElfClass::kAddrSize);
+
+  // Provide the base addresses for .eh_frame encoded pointers, if
+  // possible.
+  byte_reader.SetCFIDataBase(section->sh_addr, cfi);
+  if (got_section)
+    byte_reader.SetDataBase(got_section->sh_addr);
+  if (text_section)
+    byte_reader.SetTextBase(text_section->sh_addr);
+
+  google_breakpad::CallFrameInfo::Reporter dwarf_reporter(dwarf_filename,
+                                                       section_name);
+  if (!IsCompressedHeader<ElfClass>(section)) {
+    google_breakpad::CallFrameInfo parser(cfi, cfi_size,
+                                          &byte_reader, &handler,
+                                          &dwarf_reporter, eh_frame);
+    parser.Start();
+    return true;
+  }
+
+  typename ElfClass::Chdr chdr;
+  uint32_t compression_header_size =
+    GetCompressionHeader<ElfClass>(chdr, cfi, cfi_size);
+
+  if (compression_header_size == 0 || chdr.ch_size == 0) {
+    fprintf(stderr, "%s: decompression failed at header\n",
+            dwarf_filename.c_str());
+    return false;
+  }
+  if (compression_header_size > cfi_size) {
+    fprintf(stderr, "%s: decompression error, compression_header too large\n",
+            dwarf_filename.c_str());
+    return false;
+  }
+
+  cfi += compression_header_size;
+  cfi_size -= compression_header_size;
+
+  std::pair<uint8_t *, uint64_t> uncompressed =
+    UncompressSectionContents(chdr.ch_type, cfi, cfi_size, chdr.ch_size);
+
+  if (uncompressed.first == nullptr || uncompressed.second == 0) {
+    fprintf(stderr, "%s: decompression failed\n", dwarf_filename.c_str());
+    return false;
+  }
+  google_breakpad::CallFrameInfo parser(uncompressed.first, uncompressed.second,
+                                        &byte_reader, &handler, &dwarf_reporter,
+                                        eh_frame);
+  parser.Start();
+  return true;
+}
+
+bool LoadELF(const string& obj_file, MmapWrapper* map_wrapper,
+             void** elf_header) {
+  int obj_fd = open(obj_file.c_str(), O_RDONLY);
+  if (obj_fd < 0) {
+    fprintf(stderr, "Failed to open ELF file '%s': %s\n",
+            obj_file.c_str(), strerror(errno));
+    return false;
+  }
+  FDWrapper obj_fd_wrapper(obj_fd);
+  struct stat st;
+  if (fstat(obj_fd, &st) != 0 && st.st_size <= 0) {
+    fprintf(stderr, "Unable to fstat ELF file '%s': %s\n",
+            obj_file.c_str(), strerror(errno));
+    return false;
+  }
+  void* obj_base = mmap(NULL, st.st_size,
+                        PROT_READ | PROT_WRITE, MAP_PRIVATE, obj_fd, 0);
+  if (obj_base == MAP_FAILED) {
+    fprintf(stderr, "Failed to mmap ELF file '%s': %s\n",
+            obj_file.c_str(), strerror(errno));
+    return false;
+  }
+  map_wrapper->set(obj_base, st.st_size);
+  *elf_header = obj_base;
+  if (!IsValidElf(*elf_header)) {
+    fprintf(stderr, "Not a valid ELF file: %s\n", obj_file.c_str());
+    return false;
+  }
+  return true;
+}
+
+// Get the endianness of ELF_HEADER. If it's invalid, return false.
+template<typename ElfClass>
+bool ElfEndianness(const typename ElfClass::Ehdr* elf_header,
+                   bool* big_endian) {
+  if (elf_header->e_ident[EI_DATA] == ELFDATA2LSB) {
+    *big_endian = false;
+    return true;
+  }
+  if (elf_header->e_ident[EI_DATA] == ELFDATA2MSB) {
+    *big_endian = true;
+    return true;
+  }
+
+  fprintf(stderr, "bad data encoding in ELF header: %d\n",
+          elf_header->e_ident[EI_DATA]);
+  return false;
+}
+
+// Given |left_abspath|, find the absolute path for |right_path| and see if the
+// two absolute paths are the same.
+bool IsSameFile(const char* left_abspath, const string& right_path) {
+  char right_abspath[PATH_MAX];
+  if (!realpath(right_path.c_str(), right_abspath))
+    return false;
+  return strcmp(left_abspath, right_abspath) == 0;
+}
+
+// Read the .gnu_debuglink and get the debug file name. If anything goes
+// wrong, return an empty string.
+string ReadDebugLink(const uint8_t* debuglink,
+                     const size_t debuglink_size,
+                     const bool big_endian,
+                     const string& obj_file,
+                     const std::vector<string>& debug_dirs) {
+  // Include '\0' + CRC32 (4 bytes).
+  size_t debuglink_len = strlen(reinterpret_cast<const char*>(debuglink)) + 5;
+  debuglink_len = 4 * ((debuglink_len + 3) / 4);  // Round up to 4 bytes.
+
+  // Sanity check.
+  if (debuglink_len != debuglink_size) {
+    fprintf(stderr, "Mismatched .gnu_debuglink string / section size: "
+            "%zx %zx\n", debuglink_len, debuglink_size);
+    return string();
+  }
+
+  char obj_file_abspath[PATH_MAX];
+  if (!realpath(obj_file.c_str(), obj_file_abspath)) {
+    fprintf(stderr, "Cannot resolve absolute path for %s\n", obj_file.c_str());
+    return string();
+  }
+
+  std::vector<string> searched_paths;
+  string debuglink_path;
+  std::vector<string>::const_iterator it;
+  for (it = debug_dirs.begin(); it < debug_dirs.end(); ++it) {
+    const string& debug_dir = *it;
+    debuglink_path = debug_dir + "/" +
+                     reinterpret_cast<const char*>(debuglink);
+
+    // There is the annoying case of /path/to/foo.so having foo.so as the
+    // debug link file name. Thus this may end up opening /path/to/foo.so again,
+    // and there is a small chance of the two files having the same CRC.
+    if (IsSameFile(obj_file_abspath, debuglink_path))
+      continue;
+
+    searched_paths.push_back(debug_dir);
+    int debuglink_fd = open(debuglink_path.c_str(), O_RDONLY);
+    if (debuglink_fd < 0)
+      continue;
+
+    FDWrapper debuglink_fd_wrapper(debuglink_fd);
+
+    // The CRC is the last 4 bytes in |debuglink|.
+    const google_breakpad::Endianness endianness = big_endian ?
+        google_breakpad::ENDIANNESS_BIG : google_breakpad::ENDIANNESS_LITTLE;
+    google_breakpad::ByteReader byte_reader(endianness);
+    uint32_t expected_crc =
+        byte_reader.ReadFourBytes(&debuglink[debuglink_size - 4]);
+
+    uint32_t actual_crc = 0;
+    while (true) {
+      const size_t kReadSize = 4096;
+      char buf[kReadSize];
+      ssize_t bytes_read = HANDLE_EINTR(read(debuglink_fd, &buf, kReadSize));
+      if (bytes_read < 0) {
+        fprintf(stderr, "Error reading debug ELF file %s.\n",
+                debuglink_path.c_str());
+        return string();
+      }
+      if (bytes_read == 0)
+        break;
+      actual_crc = google_breakpad::UpdateCrc32(actual_crc, buf, bytes_read);
+    }
+    if (actual_crc != expected_crc) {
+      fprintf(stderr, "Error reading debug ELF file - CRC32 mismatch: %s\n",
+              debuglink_path.c_str());
+      continue;
+    }
+
+    // Found debug file.
+    return debuglink_path;
+  }
+
+  // Not found case.
+  fprintf(stderr, "Failed to find debug ELF file for '%s' after trying:\n",
+          obj_file.c_str());
+  for (it = searched_paths.begin(); it < searched_paths.end(); ++it) {
+    const string& debug_dir = *it;
+    fprintf(stderr, "  %s/%s\n", debug_dir.c_str(), debuglink);
+  }
+  return string();
+}
+
+//
+// LoadSymbolsInfo
+//
+// Holds the state between the two calls to LoadSymbols() in case it's necessary
+// to follow the .gnu_debuglink section and load debug information from a
+// different file.
+//
+template<typename ElfClass>
+class LoadSymbolsInfo {
+ public:
+  typedef typename ElfClass::Addr Addr;
+
+  explicit LoadSymbolsInfo(const std::vector<string>& dbg_dirs) :
+    debug_dirs_(dbg_dirs),
+    has_loading_addr_(false) {}
+
+  // Keeps track of which sections have been loaded so sections don't
+  // accidentally get loaded twice from two different files.
+  void LoadedSection(const string& section) {
+    if (loaded_sections_.count(section) == 0) {
+      loaded_sections_.insert(section);
+    } else {
+      fprintf(stderr, "Section %s has already been loaded.\n",
+              section.c_str());
+    }
+  }
+
+  // The ELF file and linked debug file are expected to have the same preferred
+  // loading address.
+  void set_loading_addr(Addr addr, const string& filename) {
+    if (!has_loading_addr_) {
+      loading_addr_ = addr;
+      loaded_file_ = filename;
+      return;
+    }
+
+    if (addr != loading_addr_) {
+      fprintf(stderr,
+              "ELF file '%s' and debug ELF file '%s' "
+              "have different load addresses.\n",
+              loaded_file_.c_str(), filename.c_str());
+      assert(false);
+    }
+  }
+
+  // Setters and getters
+  const std::vector<string>& debug_dirs() const {
+    return debug_dirs_;
+  }
+
+  string debuglink_file() const {
+    return debuglink_file_;
+  }
+  void set_debuglink_file(string file) {
+    debuglink_file_ = file;
+  }
+
+ private:
+  const std::vector<string>& debug_dirs_; // Directories in which to
+                                          // search for the debug ELF file.
+
+  string debuglink_file_;  // Full path to the debug ELF file.
+
+  bool has_loading_addr_;  // Indicate if LOADING_ADDR_ is valid.
+
+  Addr loading_addr_;  // Saves the preferred loading address from the
+                       // first call to LoadSymbols().
+
+  string loaded_file_;  // Name of the file loaded from the first call to
+                        // LoadSymbols().
+
+  std::set<string> loaded_sections_;  // Tracks the Loaded ELF sections
+                                      // between calls to LoadSymbols().
+};
+
+template<typename ElfClass>
+bool LoadSymbols(const string& obj_file,
+                 const bool big_endian,
+                 const typename ElfClass::Ehdr* elf_header,
+                 const bool read_gnu_debug_link,
+                 LoadSymbolsInfo<ElfClass>* info,
+                 const DumpOptions& options,
+                 Module* module) {
+  typedef typename ElfClass::Addr Addr;
+  typedef typename ElfClass::Phdr Phdr;
+  typedef typename ElfClass::Shdr Shdr;
+
+  Addr loading_addr = GetLoadingAddress<ElfClass>(
+      GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff),
+      elf_header->e_phnum);
+  module->SetLoadAddress(loading_addr);
+  info->set_loading_addr(loading_addr, obj_file);
+
+  // Allow filtering of extraneous debug information in partitioned libraries.
+  // Such libraries contain debug information for all libraries extracted from
+  // the same combined library, implying extensive duplication.
+  vector<Module::Range> address_ranges = GetPtLoadSegmentRanges<ElfClass>(
+      GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff),
+      elf_header->e_phnum);
+  module->SetAddressRanges(address_ranges);
+
+  const Shdr* sections =
+      GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff);
+  const Shdr* section_names = sections + elf_header->e_shstrndx;
+  const char* names =
+      GetOffset<ElfClass, char>(elf_header, section_names->sh_offset);
+  const char* names_end = names + section_names->sh_size;
+  bool found_debug_info_section = false;
+  bool found_usable_info = false;
+
+  if ((options.symbol_data & SYMBOLS_AND_FILES) ||
+      (options.symbol_data & INLINES)) {
+#ifndef NO_STABS_SUPPORT
+    // Look for STABS debugging information, and load it if present.
+    const Shdr* stab_section =
+      FindElfSectionByName<ElfClass>(".stab", SHT_PROGBITS,
+                                     sections, names, names_end,
+                                     elf_header->e_shnum);
+    if (stab_section) {
+      const Shdr* stabstr_section = stab_section->sh_link + sections;
+      if (stabstr_section) {
+        found_debug_info_section = true;
+        found_usable_info = true;
+        info->LoadedSection(".stab");
+        if (!LoadStabs<ElfClass>(elf_header, stab_section, stabstr_section,
+                                 big_endian, module)) {
+          fprintf(stderr, "%s: \".stab\" section found, but failed to load"
+                  " STABS debugging information\n", obj_file.c_str());
+        }
+      }
+    }
+#endif  // NO_STABS_SUPPORT
+
+    // See if there are export symbols available.
+    const Shdr* symtab_section =
+        FindElfSectionByName<ElfClass>(".symtab", SHT_SYMTAB,
+                                       sections, names, names_end,
+                                       elf_header->e_shnum);
+    const Shdr* strtab_section =
+        FindElfSectionByName<ElfClass>(".strtab", SHT_STRTAB,
+                                       sections, names, names_end,
+                                       elf_header->e_shnum);
+    if (symtab_section && strtab_section) {
+      info->LoadedSection(".symtab");
+
+      const uint8_t* symtab =
+          GetOffset<ElfClass, uint8_t>(elf_header,
+                                       symtab_section->sh_offset);
+      const uint8_t* strtab =
+          GetOffset<ElfClass, uint8_t>(elf_header,
+                                       strtab_section->sh_offset);
+      bool result =
+          ELFSymbolsToModule(symtab,
+                             symtab_section->sh_size,
+                             strtab,
+                             strtab_section->sh_size,
+                             big_endian,
+                             ElfClass::kAddrSize,
+                             module);
+      found_usable_info = found_usable_info || result;
+    } else {
+      // Look in dynsym only if full symbol table was not available.
+      const Shdr* dynsym_section =
+          FindElfSectionByName<ElfClass>(".dynsym", SHT_DYNSYM,
+                                         sections, names, names_end,
+                                         elf_header->e_shnum);
+      const Shdr* dynstr_section =
+          FindElfSectionByName<ElfClass>(".dynstr", SHT_STRTAB,
+                                         sections, names, names_end,
+                                         elf_header->e_shnum);
+      if (dynsym_section && dynstr_section) {
+        info->LoadedSection(".dynsym");
+
+        const uint8_t* dynsyms =
+            GetOffset<ElfClass, uint8_t>(elf_header,
+                                         dynsym_section->sh_offset);
+        const uint8_t* dynstrs =
+            GetOffset<ElfClass, uint8_t>(elf_header,
+                                         dynstr_section->sh_offset);
+        bool result =
+            ELFSymbolsToModule(dynsyms,
+                               dynsym_section->sh_size,
+                               dynstrs,
+                               dynstr_section->sh_size,
+                               big_endian,
+                               ElfClass::kAddrSize,
+                               module);
+        found_usable_info = found_usable_info || result;
+      }
+    }
+
+    // Only Load .debug_info after loading symbol table to avoid duplicate
+    // PUBLIC records.
+    // Look for DWARF debugging information, and load it if present.
+    const Shdr* dwarf_section =
+      FindElfSectionByName<ElfClass>(".debug_info", SHT_PROGBITS,
+                                     sections, names, names_end,
+                                     elf_header->e_shnum);
+
+    // .debug_info section type is SHT_PROGBITS for mips on pnacl toolchains,
+    // but MIPS_DWARF for regular gnu toolchains, so both need to be checked
+    if (elf_header->e_machine == EM_MIPS && !dwarf_section) {
+      dwarf_section =
+        FindElfSectionByName<ElfClass>(".debug_info", SHT_MIPS_DWARF,
+                                       sections, names, names_end,
+                                       elf_header->e_shnum);
+    }
+
+    if (dwarf_section) {
+      found_debug_info_section = true;
+      found_usable_info = true;
+      info->LoadedSection(".debug_info");
+      if (!LoadDwarf<ElfClass>(obj_file, elf_header, big_endian,
+                               options.handle_inter_cu_refs,
+                               options.symbol_data & INLINES, module)) {
+        fprintf(stderr, "%s: \".debug_info\" section found, but failed to load "
+                "DWARF debugging information\n", obj_file.c_str());
+      }
+    }
+  }
+
+  if (options.symbol_data & CFI) {
+    // Dwarf Call Frame Information (CFI) is actually independent from
+    // the other DWARF debugging information, and can be used alone.
+    const Shdr* dwarf_cfi_section =
+        FindElfSectionByName<ElfClass>(".debug_frame", SHT_PROGBITS,
+                                       sections, names, names_end,
+                                       elf_header->e_shnum);
+
+    // .debug_frame section type is SHT_PROGBITS for mips on pnacl toolchains,
+    // but MIPS_DWARF for regular gnu toolchains, so both need to be checked
+    if (elf_header->e_machine == EM_MIPS && !dwarf_cfi_section) {
+      dwarf_cfi_section =
+          FindElfSectionByName<ElfClass>(".debug_frame", SHT_MIPS_DWARF,
+                                        sections, names, names_end,
+                                        elf_header->e_shnum);
+    }
+
+    if (dwarf_cfi_section) {
+      // Ignore the return value of this function; even without call frame
+      // information, the other debugging information could be perfectly
+      // useful.
+      info->LoadedSection(".debug_frame");
+      bool result =
+          LoadDwarfCFI<ElfClass>(obj_file, elf_header, ".debug_frame",
+                                 dwarf_cfi_section, false, 0, 0, big_endian,
+                                 module);
+      found_usable_info = found_usable_info || result;
+    }
+
+    // Linux C++ exception handling information can also provide
+    // unwinding data.
+    const Shdr* eh_frame_section =
+        FindElfSectionByName<ElfClass>(".eh_frame", SHT_PROGBITS,
+                                       sections, names, names_end,
+                                       elf_header->e_shnum);
+    if (eh_frame_section) {
+      // Pointers in .eh_frame data may be relative to the base addresses of
+      // certain sections. Provide those sections if present.
+      const Shdr* got_section =
+          FindElfSectionByName<ElfClass>(".got", SHT_PROGBITS,
+                                         sections, names, names_end,
+                                         elf_header->e_shnum);
+      const Shdr* text_section =
+          FindElfSectionByName<ElfClass>(".text", SHT_PROGBITS,
+                                         sections, names, names_end,
+                                         elf_header->e_shnum);
+      info->LoadedSection(".eh_frame");
+      // As above, ignore the return value of this function.
+      bool result =
+          LoadDwarfCFI<ElfClass>(obj_file, elf_header, ".eh_frame",
+                                 eh_frame_section, true,
+                                 got_section, text_section, big_endian, module);
+      found_usable_info = found_usable_info || result;
+    }
+  }
+
+  if (!found_debug_info_section) {
+    fprintf(stderr, "%s: file contains no debugging information"
+            " (no \".stab\" or \".debug_info\" sections)\n",
+            obj_file.c_str());
+
+    // Failed, but maybe there's a .gnu_debuglink section?
+    if (read_gnu_debug_link) {
+      const Shdr* gnu_debuglink_section
+          = FindElfSectionByName<ElfClass>(".gnu_debuglink", SHT_PROGBITS,
+                                           sections, names,
+                                           names_end, elf_header->e_shnum);
+      if (gnu_debuglink_section) {
+        if (!info->debug_dirs().empty()) {
+          const uint8_t* debuglink_contents =
+              GetOffset<ElfClass, uint8_t>(elf_header,
+                                           gnu_debuglink_section->sh_offset);
+          string debuglink_file =
+              ReadDebugLink(debuglink_contents,
+                            gnu_debuglink_section->sh_size,
+                            big_endian,
+                            obj_file,
+                            info->debug_dirs());
+          info->set_debuglink_file(debuglink_file);
+        } else {
+          fprintf(stderr, ".gnu_debuglink section found in '%s', "
+                  "but no debug path specified.\n", obj_file.c_str());
+        }
+      } else {
+        fprintf(stderr, "%s does not contain a .gnu_debuglink section.\n",
+                obj_file.c_str());
+      }
+    } else {
+      // Return true if some usable information was found, since the caller
+      // doesn't want to use .gnu_debuglink.
+      return found_usable_info;
+    }
+
+    // No debug info was found, let the user try again with .gnu_debuglink
+    // if present.
+    return false;
+  }
+
+  return true;
+}
+
+// Return the breakpad symbol file identifier for the architecture of
+// ELF_HEADER.
+template<typename ElfClass>
+const char* ElfArchitecture(const typename ElfClass::Ehdr* elf_header) {
+  typedef typename ElfClass::Half Half;
+  Half arch = elf_header->e_machine;
+  switch (arch) {
+    case EM_386:        return "x86";
+    case EM_ARM:        return "arm";
+    case EM_AARCH64:    return "arm64";
+    case EM_MIPS:       return "mips";
+    case EM_PPC64:      return "ppc64";
+    case EM_PPC:        return "ppc";
+    case EM_S390:       return "s390";
+    case EM_SPARC:      return "sparc";
+    case EM_SPARCV9:    return "sparcv9";
+    case EM_X86_64:     return "x86_64";
+    case EM_RISCV:      return "riscv";
+    default: return NULL;
+  }
+}
+
+template<typename ElfClass>
+bool SanitizeDebugFile(const typename ElfClass::Ehdr* debug_elf_header,
+                       const string& debuglink_file,
+                       const string& obj_filename,
+                       const char* obj_file_architecture,
+                       const bool obj_file_is_big_endian) {
+  const char* debug_architecture =
+      ElfArchitecture<ElfClass>(debug_elf_header);
+  if (!debug_architecture) {
+    fprintf(stderr, "%s: unrecognized ELF machine architecture: %d\n",
+            debuglink_file.c_str(), debug_elf_header->e_machine);
+    return false;
+  }
+  if (strcmp(obj_file_architecture, debug_architecture)) {
+    fprintf(stderr, "%s with ELF machine architecture %s does not match "
+            "%s with ELF architecture %s\n",
+            debuglink_file.c_str(), debug_architecture,
+            obj_filename.c_str(), obj_file_architecture);
+    return false;
+  }
+  bool debug_big_endian;
+  if (!ElfEndianness<ElfClass>(debug_elf_header, &debug_big_endian))
+    return false;
+  if (debug_big_endian != obj_file_is_big_endian) {
+    fprintf(stderr, "%s and %s does not match in endianness\n",
+            obj_filename.c_str(), debuglink_file.c_str());
+    return false;
+  }
+  return true;
+}
+
+template<typename ElfClass>
+bool InitModuleForElfClass(const typename ElfClass::Ehdr* elf_header,
+                           const string& obj_filename,
+                           const string& obj_os,
+                           scoped_ptr<Module>& module,
+                           bool enable_multiple_field) {
+  PageAllocator allocator;
+  wasteful_vector<uint8_t> identifier(&allocator, kDefaultBuildIdSize);
+  if (!FileID::ElfFileIdentifierFromMappedFile(elf_header, identifier)) {
+    fprintf(stderr, "%s: unable to generate file identifier\n",
+            obj_filename.c_str());
+    return false;
+  }
+
+  const char* architecture = ElfArchitecture<ElfClass>(elf_header);
+  if (!architecture) {
+    fprintf(stderr, "%s: unrecognized ELF machine architecture: %d\n",
+            obj_filename.c_str(), elf_header->e_machine);
+    return false;
+  }
+
+  char name_buf[NAME_MAX] = {};
+  std::string name = google_breakpad::ElfFileSoNameFromMappedFile(
+                         elf_header, name_buf, sizeof(name_buf))
+                         ? name_buf
+                         : google_breakpad::BaseName(obj_filename);
+
+  // Add an extra "0" at the end.  PDB files on Windows have an 'age'
+  // number appended to the end of the file identifier; this isn't
+  // really used or necessary on other platforms, but be consistent.
+  string id = FileID::ConvertIdentifierToUUIDString(identifier) + "0";
+  // This is just the raw Build ID in hex.
+  string code_id = FileID::ConvertIdentifierToString(identifier);
+
+  module.reset(new Module(name, obj_os, architecture, id, code_id,
+                          enable_multiple_field));
+
+  return true;
+}
+
+template<typename ElfClass>
+bool ReadSymbolDataElfClass(const typename ElfClass::Ehdr* elf_header,
+                            const string& obj_filename,
+                            const string& obj_os,
+                            const std::vector<string>& debug_dirs,
+                            const DumpOptions& options,
+                            Module** out_module) {
+  typedef typename ElfClass::Ehdr Ehdr;
+
+  *out_module = NULL;
+
+  scoped_ptr<Module> module;
+  if (!InitModuleForElfClass<ElfClass>(elf_header, obj_filename, obj_os, module,
+                                       options.enable_multiple_field)) {
+    return false;
+  }
+
+  // Figure out what endianness this file is.
+  bool big_endian;
+  if (!ElfEndianness<ElfClass>(elf_header, &big_endian))
+    return false;
+
+  LoadSymbolsInfo<ElfClass> info(debug_dirs);
+  if (!LoadSymbols<ElfClass>(obj_filename, big_endian, elf_header,
+                             !debug_dirs.empty(), &info,
+                             options, module.get())) {
+    const string debuglink_file = info.debuglink_file();
+    if (debuglink_file.empty())
+      return false;
+
+    // Load debuglink ELF file.
+    fprintf(stderr, "Found debugging info in %s\n", debuglink_file.c_str());
+    MmapWrapper debug_map_wrapper;
+    Ehdr* debug_elf_header = NULL;
+    if (!LoadELF(debuglink_file, &debug_map_wrapper,
+                 reinterpret_cast<void**>(&debug_elf_header)) ||
+        !SanitizeDebugFile<ElfClass>(debug_elf_header, debuglink_file,
+                                     obj_filename,
+                                     module->architecture().c_str(),
+                                     big_endian)) {
+      return false;
+    }
+
+    if (!LoadSymbols<ElfClass>(debuglink_file, big_endian,
+                               debug_elf_header, false, &info,
+                               options, module.get())) {
+      return false;
+    }
+  }
+
+  *out_module = module.release();
+  return true;
+}
+
+}  // namespace
+
+namespace google_breakpad {
+
+// Not explicitly exported, but not static so it can be used in unit tests.
+bool ReadSymbolDataInternal(const uint8_t* obj_file,
+                            const string& obj_filename,
+                            const string& obj_os,
+                            const std::vector<string>& debug_dirs,
+                            const DumpOptions& options,
+                            Module** module) {
+  if (!IsValidElf(obj_file)) {
+    fprintf(stderr, "Not a valid ELF file: %s\n", obj_filename.c_str());
+    return false;
+  }
+
+  int elfclass = ElfClass(obj_file);
+  if (elfclass == ELFCLASS32) {
+    return ReadSymbolDataElfClass<ElfClass32>(
+        reinterpret_cast<const Elf32_Ehdr*>(obj_file), obj_filename, obj_os,
+        debug_dirs, options, module);
+  }
+  if (elfclass == ELFCLASS64) {
+    return ReadSymbolDataElfClass<ElfClass64>(
+        reinterpret_cast<const Elf64_Ehdr*>(obj_file), obj_filename, obj_os,
+        debug_dirs, options, module);
+  }
+
+  return false;
+}
+
+bool WriteSymbolFile(const string& load_path,
+                     const string& obj_file,
+                     const string& obj_os,
+                     const std::vector<string>& debug_dirs,
+                     const DumpOptions& options,
+                     std::ostream& sym_stream) {
+  Module* module;
+  if (!ReadSymbolData(load_path, obj_file, obj_os, debug_dirs, options,
+                      &module))
+    return false;
+
+  bool result = module->Write(sym_stream, options.symbol_data);
+  delete module;
+  return result;
+}
+
+// Read the selected object file's debugging information, and write out the
+// header only to |stream|. Return true on success; if an error occurs, report
+// it and return false.
+bool WriteSymbolFileHeader(const string& load_path,
+                           const string& obj_file,
+                           const string& obj_os,
+                           std::ostream& sym_stream) {
+  MmapWrapper map_wrapper;
+  void* elf_header = NULL;
+  if (!LoadELF(load_path, &map_wrapper, &elf_header)) {
+    fprintf(stderr, "Could not load ELF file: %s\n", obj_file.c_str());
+    return false;
+  }
+
+  if (!IsValidElf(elf_header)) {
+    fprintf(stderr, "Not a valid ELF file: %s\n", obj_file.c_str());
+    return false;
+  }
+
+  int elfclass = ElfClass(elf_header);
+  scoped_ptr<Module> module;
+  if (elfclass == ELFCLASS32) {
+    if (!InitModuleForElfClass<ElfClass32>(
+        reinterpret_cast<const Elf32_Ehdr*>(elf_header), obj_file, obj_os,
+        module, /*enable_multiple_field=*/false)) {
+      fprintf(stderr, "Failed to load ELF module: %s\n", obj_file.c_str());
+      return false;
+    }
+  } else if (elfclass == ELFCLASS64) {
+    if (!InitModuleForElfClass<ElfClass64>(
+        reinterpret_cast<const Elf64_Ehdr*>(elf_header), obj_file, obj_os,
+        module, /*enable_multiple_field=*/false)) {
+      fprintf(stderr, "Failed to load ELF module: %s\n", obj_file.c_str());
+      return false;
+    }
+  } else {
+    fprintf(stderr, "Unsupported module file: %s\n", obj_file.c_str());
+    return false;
+  }
+
+  return module->Write(sym_stream, ALL_SYMBOL_DATA);
+}
+
+bool ReadSymbolData(const string& load_path,
+                    const string& obj_file,
+                    const string& obj_os,
+                    const std::vector<string>& debug_dirs,
+                    const DumpOptions& options,
+                    Module** module) {
+  MmapWrapper map_wrapper;
+  void* elf_header = NULL;
+  if (!LoadELF(load_path, &map_wrapper, &elf_header))
+    return false;
+
+  return ReadSymbolDataInternal(reinterpret_cast<uint8_t*>(elf_header),
+                                obj_file, obj_os, debug_dirs, options, module);
+}
+
+}  // namespace google_breakpad