src/common/linux/elfutils.h

// Copyright (c) 2012, Google Inc.
// All rights reserved.
//
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// 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.
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// 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,
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// 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.
//
// elfutils.h: Utilities for dealing with ELF files.
//

#ifndef COMMON_LINUX_ELFUTILS_H_
#define COMMON_LINUX_ELFUTILS_H_

#include <elf.h>
#include <link.h>
#include <stdint.h>

#include "common/memory_allocator.h"

namespace google_breakpad {

// Traits classes so consumers can write templatized code to deal
// with specific ELF bits.
struct ElfClass32 {
  typedef Elf32_Addr Addr;
  typedef Elf32_Dyn Dyn;
  typedef Elf32_Ehdr Ehdr;
  typedef Elf32_Nhdr Nhdr;
  typedef Elf32_Phdr Phdr;
  typedef Elf32_Shdr Shdr;
  typedef Elf32_Half Half;
  typedef Elf32_Off Off;
  typedef Elf32_Sym Sym;
  typedef Elf32_Word Word;

  static const int kClass = ELFCLASS32;
  static const uint16_t kMachine = EM_386;
  static const size_t kAddrSize = sizeof(Elf32_Addr);
  static constexpr const char* kMachineName = "x86";
};

struct ElfClass64 {
  typedef Elf64_Addr Addr;
  typedef Elf64_Dyn Dyn;
  typedef Elf64_Ehdr Ehdr;
  typedef Elf64_Nhdr Nhdr;
  typedef Elf64_Phdr Phdr;
  typedef Elf64_Shdr Shdr;
  typedef Elf64_Half Half;
  typedef Elf64_Off Off;
  typedef Elf64_Sym Sym;
  typedef Elf64_Word Word;

  static const int kClass = ELFCLASS64;
  static const uint16_t kMachine = EM_X86_64;
  static const size_t kAddrSize = sizeof(Elf64_Addr);
  static constexpr const char* kMachineName = "x86_64";
};

bool IsValidElf(const void* elf_header);
int ElfClass(const void* elf_base);

// Attempt to find a section named |section_name| of type |section_type|
// in the ELF binary data at |elf_mapped_base|. On success, returns true
// and sets |*section_start| to point to the start of the section data,
// and |*section_size| to the size of the section's data.
bool FindElfSection(const void* elf_mapped_base,
                    const char* section_name,
                    uint32_t section_type,
                    const void** section_start,
                    size_t* section_size);

// Internal helper method, exposed for convenience for callers
// that already have more info.
template<typename ElfClass>
const typename ElfClass::Shdr*
FindElfSectionByName(const char* name,
                     typename ElfClass::Word section_type,
                     const typename ElfClass::Shdr* sections,
                     const char* section_names,
                     const char* names_end,
                     int nsection);

struct ElfSegment {
  const void* start;
  size_t size;
};

// Attempt to find all segments of type |segment_type| in the ELF
// binary data at |elf_mapped_base|. On success, returns true and fills
// |*segments| with a list of segments of the given type.
bool FindElfSegments(const void* elf_mapped_base,
                     uint32_t segment_type,
                     wasteful_vector<ElfSegment>* segments);

// Convert an offset from an Elf header into a pointer to the mapped
// address in the current process. Takes an extra template parameter
// to specify the return type to avoid having to dynamic_cast the
// result.
template<typename ElfClass, typename T>
const T*
GetOffset(const typename ElfClass::Ehdr* elf_header,
          typename ElfClass::Off offset);

// Read the value of DT_SONAME from the elf file mapped at |elf_base|. Returns
// true and fills |soname| with the result if found.
bool ElfFileSoNameFromMappedFile(const void* elf_base,
                                 char* soname,
                                 size_t soname_size);

}  // namespace google_breakpad

#endif  // COMMON_LINUX_ELFUTILS_H_