elfFile.hpp

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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#ifndef SHARE_VM_UTILITIES_ELF_FILE_HPP
#define SHARE_VM_UTILITIES_ELF_FILE_HPP

#if !defined(_WINDOWS) && !defined(__APPLE__)

#if defined(__OpenBSD__)
#include <sys/exec_elf.h>
#else
#include <elf.h>
#endif
#include <stdio.h>

#ifdef _LP64

typedef Elf64_Half      Elf_Half;
typedef Elf64_Word      Elf_Word;
typedef Elf64_Off       Elf_Off;
typedef Elf64_Addr      Elf_Addr;

typedef Elf64_Ehdr      Elf_Ehdr;
typedef Elf64_Shdr      Elf_Shdr;
typedef Elf64_Phdr      Elf_Phdr;
typedef Elf64_Sym       Elf_Sym;

#if !defined(__ANDROID__) && (!defined(_ALLBSD_SOURCE) || defined(__APPLE__))
#define ELF_ST_TYPE ELF64_ST_TYPE
#endif

#else

typedef Elf32_Half      Elf_Half;
typedef Elf32_Word      Elf_Word;
typedef Elf32_Off       Elf_Off;
typedef Elf32_Addr      Elf_Addr;


typedef Elf32_Ehdr      Elf_Ehdr;
typedef Elf32_Shdr      Elf_Shdr;
typedef Elf32_Phdr      Elf_Phdr;
typedef Elf32_Sym       Elf_Sym;

#if !defined(__ANDROID__) && (!defined(_ALLBSD_SOURCE) || defined(__APPLE__))
#define ELF_ST_TYPE ELF32_ST_TYPE
#endif
#endif

#include "globalDefinitions.hpp"
#include "memory/allocation.hpp"
#include "utilities/decoder.hpp"


class ElfStringTable;
class ElfSymbolTable;
class ElfFuncDescTable;


// On Solaris/Linux platforms, libjvm.so does contain all private symbols.
// ElfFile is basically an elf file parser, which can lookup the symbol
// that is the nearest to the given address.
// Beware, this code is called from vm error reporting code, when vm is already
// in "error" state, so there are scenarios, lookup will fail. We want this
// part of code to be very defensive, and bait out if anything went wrong.

class ElfFile: public CHeapObj<mtInternal> {
  friend class ElfDecoder;
 public:
  ElfFile(const char* filepath);
  ~ElfFile();

  bool decode(address addr, char* buf, int buflen, int* offset);
  const char* filepath() {
    return m_filepath;
  }

  bool same_elf_file(const char* filepath) {
    assert(filepath, "null file path");
    assert(m_filepath, "already out of memory");
    return (m_filepath && !strcmp(filepath, m_filepath));
  }

  NullDecoder::decoder_status get_status() {
    return m_status;
  }

 private:
  // sanity check, if the file is a real elf file
  bool is_elf_file(Elf_Ehdr&);

  // load string tables from the elf file
  bool load_tables();

  // string tables are stored in a linked list
  void add_string_table(ElfStringTable* table);

  // symbol tables are stored in a linked list
  void add_symbol_table(ElfSymbolTable* table);

  // return a string table at specified section index
  ElfStringTable* get_string_table(int index);

protected:
   ElfFile*  next() const { return m_next; }
   void set_next(ElfFile* file) { m_next = file; }

 public:
  // Returns true if the elf file is marked NOT to require an executable stack,
  // or if the file could not be opened.
  // Returns false if the elf file requires an executable stack, the stack flag
  // is not set at all, or if the file can not be read.
  // On systems other than linux it always returns false.
  bool specifies_noexecstack() NOT_LINUX({ return false; });

 protected:
    ElfFile*         m_next;

 private:
  // file
  const char* m_filepath;
  FILE* m_file;

  // Elf header
  Elf_Ehdr                     m_elfHdr;

  // symbol tables
  ElfSymbolTable*              m_symbol_tables;

  // string tables
  ElfStringTable*              m_string_tables;

  // function descriptors table
  ElfFuncDescTable*            m_funcDesc_table;

  NullDecoder::decoder_status  m_status;
};

#endif // !_WINDOWS && !__APPLE__

#endif // SHARE_VM_UTILITIES_ELF_FILE_HPP