elfStringTable.cpp revision 3718:b9a9ed0f8eeb 
1/*
2 * Copyright (c) 1997, 2012, 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.
35ElfStringTable::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, mtInternal);
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
60ElfStringTable::~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
70bool 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
91