1 /*
   2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 
  27 #if !defined(_WINDOWS) && !defined(__APPLE__)
  28 
  29 #include "memory/allocation.inline.hpp"
  30 #include "runtime/os.hpp"
  31 #include "utilities/elfStringTable.hpp"
  32 
  33 // We will try to load whole string table into memory if we can.
  34 // Otherwise, fallback to more expensive file operation.
  35 ElfStringTable::ElfStringTable(FILE* file, Elf_Shdr shdr, int index) {
  36   assert(file, "null file handle");
  37   m_table = NULL;
  38   m_index = index;
  39   m_next = NULL;
  40   m_file = file;
  41   m_status = NullDecoder::no_error;
  42 
  43   // try to load the string table
  44   long cur_offset = ftell(file);
  45   m_table = (char*)os::malloc(sizeof(char) * shdr.sh_size);
  46   if (m_table != NULL) {
  47     // if there is an error, mark the error
  48     if (fseek(file, shdr.sh_offset, SEEK_SET) ||
  49       fread((void*)m_table, shdr.sh_size, 1, file) != 1 ||
  50       fseek(file, cur_offset, SEEK_SET)) {
  51       m_status = NullDecoder::file_invalid;
  52       os::free((void*)m_table);
  53       m_table = NULL;
  54     }
  55   } else {
  56     memcpy(&m_shdr, &shdr, sizeof(Elf_Shdr));
  57   }
  58 }
  59 
  60 ElfStringTable::~ElfStringTable() {
  61   if (m_table != NULL) {
  62     os::free((void*)m_table);
  63   }
  64 
  65   if (m_next != NULL) {
  66     delete m_next;
  67   }
  68 }
  69 
  70 bool ElfStringTable::string_at(int pos, char* buf, int buflen) {
  71   if (NullDecoder::is_error(m_status)) {
  72     return false;
  73   }
  74   if (m_table != NULL) {
  75     jio_snprintf(buf, buflen, "%s", (const char*)(m_table + pos));
  76     return true;
  77   } else {
  78     long cur_pos = ftell(m_file);
  79     if (cur_pos == -1 ||
  80       fseek(m_file, m_shdr.sh_offset + pos, SEEK_SET) ||
  81       fread(buf, 1, buflen, m_file) <= 0 ||
  82       fseek(m_file, cur_pos, SEEK_SET)) {
  83       m_status = NullDecoder::file_invalid;
  84       return false;
  85     }
  86     return true;
  87   }
  88 }
  89 
  90 #endif // _WINDOWS