/*

 * 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.

 *

 */

#include "precompiled.hpp"

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

#include <string.h>

#include <stdio.h>

#include <limits.h>

#include <new>

#include "logging/log.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

#include "utilities/decoder.hpp"

#include "utilities/elfFile.hpp"

#include "utilities/elfFuncDescTable.hpp"

#include "utilities/elfStringTable.hpp"

#include "utilities/elfSymbolTable.hpp"

#include "utilities/ostream.hpp"

// For test only, disable elf section cache and force to read from file directly.

bool ElfFile::_do_not_cache_elf_section = false;

ElfSection::ElfSection(FILE* fd, const Elf_Shdr& hdr) : _section_data(NULL) {

  _stat = load_section(fd, hdr);

}

ElfSection::~ElfSection() {

  if (_section_data != NULL) {

    os::free(_section_data);

  }

}

NullDecoder::decoder_status ElfSection::load_section(FILE* const fd, const Elf_Shdr& shdr) {

  memcpy((void*)&_section_hdr, (const void*)&shdr, sizeof(shdr));

  if (ElfFile::_do_not_cache_elf_section) {

    log_debug(decoder)("Elf section cache is disabled");

    return NullDecoder::no_error;

  }

  _section_data = os::malloc(shdr.sh_size, mtInternal);

  // No enough memory for caching. It is okay, we can try to read from

  // file instead.

  if (_section_data == NULL) return NullDecoder::no_error;

  MarkedFileReader mfd(fd);

  if (mfd.has_mark() &&

      mfd.set_position(shdr.sh_offset) &&

      mfd.read(_section_data, shdr.sh_size)) {

    return NullDecoder::no_error;

  } else {

    os::free(_section_data);

    _section_data = NULL;

    return NullDecoder::file_invalid;

  }

}

bool FileReader::read(void* buf, size_t size) {

  assert(buf != NULL, "no buffer");

  assert(size > 0, "no space");

  return fread(buf, size, 1, _fd) == 1;

}

int FileReader::read_buffer(void* buf, size_t size) {

  assert(buf != NULL, "no buffer");

  assert(size > 0, "no space");

  return fread(buf, 1, size, _fd);

}

bool FileReader::set_position(long offset) {

  return fseek(_fd, offset, SEEK_SET) == 0;

}

MarkedFileReader::MarkedFileReader(FILE* fd) : FileReader(fd) {

  _marked_pos = ftell(fd);

}

MarkedFileReader::~MarkedFileReader() {

  if (_marked_pos != -1) {

    set_position(_marked_pos);

  }

}

ElfFile::ElfFile(const char* filepath) :

  _next(NULL), _filepath(NULL), _file(NULL),

  _symbol_tables(NULL), _string_tables(NULL), _shdr_string_table(NULL), _funcDesc_table(NULL),

  _status(NullDecoder::no_error) {

  memset(&_elfHdr, 0, sizeof(_elfHdr));

  int len = strlen(filepath) + 1;

  _filepath = (char*)os::malloc(len * sizeof(char), mtInternal);

  if (_filepath == NULL) {

    _status = NullDecoder::out_of_memory;

    return;

  }

  strcpy(_filepath, filepath);

  _status = parse_elf(filepath);

  // we no longer need section header string table

  if (_shdr_string_table != NULL) {

    delete _shdr_string_table;

    _shdr_string_table = NULL;

  }

}

ElfFile::~ElfFile() {

  if (_shdr_string_table != NULL) {

    delete _shdr_string_table;

  }

  cleanup_tables();

  if (_file != NULL) {

    fclose(_file);

  }

  if (_filepath != NULL) {

    os::free((void*)_filepath);

  }

  if (_next != NULL) {

    delete _next;

  }

}

void ElfFile::cleanup_tables() {

  if (_string_tables != NULL) {

    delete _string_tables;

    _string_tables = NULL;

  }

  if (_symbol_tables != NULL) {

    delete _symbol_tables;

    _symbol_tables = NULL;

  }

  if (_funcDesc_table != NULL) {

    delete _funcDesc_table;

    _funcDesc_table = NULL;

  }

}

NullDecoder::decoder_status ElfFile::parse_elf(const char* filepath) {

  assert(filepath, "null file path");

  _file = fopen(filepath, "r");

  if (_file != NULL) {

    return load_tables();

  } else {

    return NullDecoder::file_not_found;

  }

}

//Check elf header to ensure the file is valid.

bool ElfFile::is_elf_file(Elf_Ehdr& hdr) {

  return (ELFMAG0 == hdr.e_ident[EI_MAG0] &&

      ELFMAG1 == hdr.e_ident[EI_MAG1] &&

      ELFMAG2 == hdr.e_ident[EI_MAG2] &&

      ELFMAG3 == hdr.e_ident[EI_MAG3] &&

      ELFCLASSNONE != hdr.e_ident[EI_CLASS] &&

      ELFDATANONE != hdr.e_ident[EI_DATA]);

}

NullDecoder::decoder_status ElfFile::load_tables() {

  assert(_file, "file not open");

  assert(!NullDecoder::is_error(_status), "already in error");

  FileReader freader(fd());

  // read elf file header

  if (!freader.read(&_elfHdr, sizeof(_elfHdr))) {

    return NullDecoder::file_invalid;

  }

  // Check signature

  if (!is_elf_file(_elfHdr)) {

    return NullDecoder::file_invalid;

  }

  // walk elf file's section headers, and load string tables

  Elf_Shdr shdr;

  if (!freader.set_position(_elfHdr.e_shoff)) {

    return NullDecoder::file_invalid;

  }

  for (int index = 0; index < _elfHdr.e_shnum; index ++) {

    if (!freader.read(&shdr, sizeof(shdr))) {

      return NullDecoder::file_invalid;

    }

    if (shdr.sh_type == SHT_STRTAB) {

      // string tables

      ElfStringTable* table = new (std::nothrow) ElfStringTable(fd(), shdr, index);

      if (table == NULL) {

        return NullDecoder::out_of_memory;

      }

      if (index == _elfHdr.e_shstrndx) {

        assert(_shdr_string_table == NULL, "Only set once");

        _shdr_string_table = table;

      } else {

        add_string_table(table);

      }

    } else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {

      // symbol tables

      ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(fd(), shdr);

      if (table == NULL) {

        return NullDecoder::out_of_memory;

      }

      add_symbol_table(table);

    }

  }

#if defined(PPC64) && !defined(ABI_ELFv2)

  // Now read the .opd section wich contains the PPC64 function descriptor table.

  // The .opd section is only available on PPC64 (see for example:

  // http://refspecs.linuxfoundation.org/LSB_3.1.1/LSB-Core-PPC64/LSB-Core-PPC64/specialsections.html)

  // so this code should do no harm on other platforms but because of performance reasons we only

  // execute it on PPC64 platforms.

  // Notice that we can only find the .opd section after we have successfully read in the string

  // tables in the previous loop, because we need to query the name of each section which is

  // contained in one of the string tables (i.e. the one with the index m_elfHdr.e_shstrndx).

  // Reset the file pointer

  int sect_index = section_by_name(".opd", shdr);

  if (sect_index == -1) {

    return NullDecoder::file_invalid;

  }

  _funcDesc_table = new (std::nothrow) ElfFuncDescTable(_file, shdr, sect_index);

  if (_funcDesc_table == NULL) {

      return NullDecoder::out_of_memory;

  }

#endif

  return NullDecoder::no_error;

}

int ElfFile::section_by_name(const char* name, Elf_Shdr& hdr) {

  assert(name != NULL, "No section name");

  size_t len = strlen(name) + 1;

  ResourceMark rm;

  char* buf = NEW_RESOURCE_ARRAY(char, len);

  if (buf == NULL) {

    return -1;

  }

  assert(_shdr_string_table != NULL, "Section header string table should be loaded");

  ElfStringTable* const table = _shdr_string_table;

  MarkedFileReader mfd(fd());

  if (!mfd.has_mark() || !mfd.set_position(_elfHdr.e_shoff)) return -1;

  int sect_index = -1;

  for (int index = 0; index < _elfHdr.e_shnum; index ++) {

    if (!mfd.read((void*)&hdr, sizeof(hdr))) {

      break;

    }

    if (table->string_at(hdr.sh_name, buf, len)) {

      if (strncmp(buf, name, len) == 0) {

        sect_index = index;

        break;

      }

    }

  }

  return sect_index;

}

bool ElfFile::decode(address addr, char* buf, int buflen, int* offset) {

  // something already went wrong, just give up

  if (NullDecoder::is_error(_status)) {

    return false;

  }

  int string_table_index;

  int pos_in_string_table;

  int off = INT_MAX;

  bool found_symbol = false;

  ElfSymbolTable* symbol_table = _symbol_tables;

  while (symbol_table != NULL) {

    if (symbol_table->lookup(addr, &string_table_index, &pos_in_string_table, &off, _funcDesc_table)) {

      found_symbol = true;

      break;

    }

    symbol_table = symbol_table->next();

  }

  if (!found_symbol) {

    return false;

  }

  ElfStringTable* string_table = get_string_table(string_table_index);

  if (string_table == NULL) {

    _status = NullDecoder::file_invalid;

    return false;

  }

  if (offset) *offset = off;

  return string_table->string_at(pos_in_string_table, buf, buflen);

}

void ElfFile::add_symbol_table(ElfSymbolTable* table) {

  if (_symbol_tables == NULL) {

    _symbol_tables = table;

  } else {

    table->set_next(_symbol_tables);

    _symbol_tables = table;

  }

}

void ElfFile::add_string_table(ElfStringTable* table) {

  if (_string_tables == NULL) {

    _string_tables = table;

  } else {

    table->set_next(_string_tables);

    _string_tables = table;

  }

}

ElfStringTable* ElfFile::get_string_table(int index) {

  ElfStringTable* p = _string_tables;

  while (p != NULL) {

    if (p->index() == index) return p;

    p = p->next();

  }

  return NULL;

}

#endif // !_WINDOWS && !__APPLE__