1 /*

     2  * Copyright (c) 1997, 2017, 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 "prims/jvm.h"

    31 #include "runtime/os.hpp"

    32 #include "utilities/elfStringTable.hpp"

    33 

    34 // We will try to load whole string table into memory if we can.

    35 // Otherwise, fallback to more expensive file operation.

    36 ElfStringTable::ElfStringTable(FILE* file, Elf_Shdr shdr, int index) {

    37   assert(file, "null file handle");

    38   m_table = NULL;

    39   m_index = index;

    40   m_next = NULL;

    41   m_file = file;

    42   m_status = NullDecoder::no_error;

    43 

    44   // try to load the string table

    45   long cur_offset = ftell(file);

    46   m_table = (char*)os::malloc(sizeof(char) * shdr.sh_size, mtInternal);

    47   if (m_table != NULL) {

    48     // if there is an error, mark the error

    49     if (fseek(file, shdr.sh_offset, SEEK_SET) ||

    50       fread((void*)m_table, shdr.sh_size, 1, file) != 1 ||

    51       fseek(file, cur_offset, SEEK_SET)) {

    52       m_status = NullDecoder::file_invalid;

    53       os::free((void*)m_table);

    54       m_table = NULL;

    55     }

    56   } else {

    57     memcpy(&m_shdr, &shdr, sizeof(Elf_Shdr));

    58   }

    59 }

    60 

    61 ElfStringTable::~ElfStringTable() {

    62   if (m_table != NULL) {

    63     os::free((void*)m_table);

    64   }

    65 

    66   if (m_next != NULL) {

    67     delete m_next;

    68   }

    69 }

    70 

    71 bool ElfStringTable::string_at(int pos, char* buf, int buflen) {

    72   if (NullDecoder::is_error(m_status)) {

    73     return false;

    74   }

    75   if (m_table != NULL) {

    76     jio_snprintf(buf, buflen, "%s", (const char*)(m_table + pos));

    77     return true;

    78   } else {

    79     long cur_pos = ftell(m_file);

    80     if (cur_pos == -1 ||

    81       fseek(m_file, m_shdr.sh_offset + pos, SEEK_SET) ||

    82       fread(buf, 1, buflen, m_file) <= 0 ||

    83       fseek(m_file, cur_pos, SEEK_SET)) {

    84       m_status = NullDecoder::file_invalid;

    85       return false;

    86     }

    87     return true;

    88   }

    89 }

    90 

    91 #endif // !_WINDOWS && !__APPLE__