/*

 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_VM_UTILITIES_ELF_FILE_HPP

#define SHARE_VM_UTILITIES_ELF_FILE_HPP

#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(_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(_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;

// ELF section, may or may not have cached data

class ElfSection VALUE_OBJ_CLASS_SPEC {

private:

  Elf_Shdr      _section_hdr;

  void*         _section_data;

  NullDecoder::decoder_status _stat;

public:

  ElfSection(FILE* fd, const Elf_Shdr& hdr);

  ~ElfSection();

  NullDecoder::decoder_status status() const { return _stat; }

  const Elf_Shdr* section_header() const { return &_section_hdr; }

  const void*     section_data()   const { return (const void*)_section_data; }

private:

  // load this section.

  // it return no_error, when it fails to cache the section data due to lack of memory

  NullDecoder::decoder_status load_section(FILE* const file, const Elf_Shdr& hdr);

};

class FileReader : public StackObj {

protected:

  FILE* const _fd;

public:

  FileReader(FILE* const fd) : _fd(fd) {};

  bool read(void* buf, size_t size);

  int  read_buffer(void* buf, size_t size);

  bool set_position(long offset);

};

// Mark current position, so we can get back to it after

// reads.

class MarkedFileReader : public FileReader {

private:

  long  _marked_pos;

public:

  MarkedFileReader(FILE* const fd);

  ~MarkedFileReader();

  bool has_mark() const { return _marked_pos >= 0; }

};

// 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;

private:

  // link ElfFiles

  ElfFile*          _next;

  // Elf file

  char*             _filepath;

  FILE*             _file;

  // Elf header

  Elf_Ehdr          _elfHdr;

  // symbol tables

  ElfSymbolTable*   _symbol_tables;

  // regular string tables

  ElfStringTable*   _string_tables;

  // section header string table, used for finding section name

  ElfStringTable*   _shdr_string_table;

  // function descriptors table

  ElfFuncDescTable* _funcDesc_table;

  NullDecoder::decoder_status  _status;

public:

  ElfFile(const char* filepath);

  ~ElfFile();

  bool decode(address addr, char* buf, int buflen, int* offset);

  const char* filepath() const {

    return _filepath;

  }

  bool same_elf_file(const char* filepath) const {

    assert(filepath != NULL, "null file path");

    return (_filepath != NULL && !strcmp(filepath, _filepath));

  }

  NullDecoder::decoder_status get_status() const {

    return _status;

  }

  // 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.

  static bool specifies_noexecstack(const char* filepath) NOT_LINUX({ return false; });

private:

  // sanity check, if the file is a real elf file

  static bool is_elf_file(Elf_Ehdr&);

  // parse this elf file

  NullDecoder::decoder_status parse_elf(const char* filename);

  // load string, symbol and function descriptor tables from the elf file

  NullDecoder::decoder_status load_tables();

  ElfFile*  next() const { return _next; }

  void set_next(ElfFile* file) { _next = file; }

  // find a section by name, return section index

  // if there is no such section, return -1

  int section_by_name(const char* name, Elf_Shdr& hdr);

  // 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);

  FILE* const fd() const { return _file; }

  // Cleanup string, symbol and function descriptor tables

  void cleanup_tables();

public:

  // For whitebox test

  static bool _do_not_cache_elf_section;

};

#endif // !_WINDOWS && !__APPLE__

#endif // SHARE_VM_UTILITIES_ELF_FILE_HPP