jdk8-mips64-public/hotspot: src/share/vm/utilities/elfFile.cpp@e5003079dfa5

     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  */

    25 #include "precompiled.hpp"

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

    29 #include <string.h>

    30 #include <stdio.h>

    31 #include <limits.h>

    32 #include <new>

    34 #include "memory/allocation.inline.hpp"

    35 #include "utilities/decoder.hpp"

    36 #include "utilities/elfFile.hpp"

    37 #include "utilities/elfStringTable.hpp"

    38 #include "utilities/elfSymbolTable.hpp"

    41 ElfFile::ElfFile(const char* filepath) {

    42   assert(filepath, "null file path");

    43   memset(&m_elfHdr, 0, sizeof(m_elfHdr));

    44   m_string_tables = NULL;

    45   m_symbol_tables = NULL;

    46   m_next = NULL;

    47   m_status = NullDecoder::no_error;

    49   int len = strlen(filepath) + 1;

    50   m_filepath = (const char*)os::malloc(len * sizeof(char), mtInternal);

    51   if (m_filepath != NULL) {

    52     strcpy((char*)m_filepath, filepath);

    53     m_file = fopen(filepath, "r");

    54     if (m_file != NULL) {

    55       load_tables();

    56     } else {

    57       m_status = NullDecoder::file_not_found;

    58     }

    59   } else {

    60     m_status = NullDecoder::out_of_memory;

    61   }

    62 }

    64 ElfFile::~ElfFile() {

    65   if (m_string_tables != NULL) {

    66     delete m_string_tables;

    67   }

    69   if (m_symbol_tables != NULL) {

    70     delete m_symbol_tables;

    71   }

    73   if (m_file != NULL) {

    74     fclose(m_file);

    75   }

    77   if (m_filepath != NULL) {

    78     os::free((void*)m_filepath);

    79   }

    81   if (m_next != NULL) {

    82     delete m_next;

    83   }

    84 };

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

    88 bool ElfFile::is_elf_file(Elf_Ehdr& hdr) {

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

    90       ELFMAG1 == hdr.e_ident[EI_MAG1] &&

    91       ELFMAG2 == hdr.e_ident[EI_MAG2] &&

    92       ELFMAG3 == hdr.e_ident[EI_MAG3] &&

    93       ELFCLASSNONE != hdr.e_ident[EI_CLASS] &&

    94       ELFDATANONE != hdr.e_ident[EI_DATA]);

    95 }

    97 bool ElfFile::load_tables() {

    98   assert(m_file, "file not open");

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

   101   // read elf file header

   102   if (fread(&m_elfHdr, sizeof(m_elfHdr), 1, m_file) != 1) {

   103     m_status = NullDecoder::file_invalid;

   104     return false;

   105   }

   107   if (!is_elf_file(m_elfHdr)) {

   108     m_status = NullDecoder::file_invalid;

   109     return false;

   110   }

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

   113   Elf_Shdr shdr;

   114   if (!fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {

   115     if (NullDecoder::is_error(m_status)) return false;

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

   118       if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {

   119         m_status = NullDecoder::file_invalid;

   120         return false;

   121       }

   122       // string table

   123       if (shdr.sh_type == SHT_STRTAB) {

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

   125         if (table == NULL) {

   126           m_status = NullDecoder::out_of_memory;

   127           return false;

   128         }

   129         add_string_table(table);

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

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

   132         if (table == NULL) {

   133           m_status = NullDecoder::out_of_memory;

   134           return false;

   135         }

   136         add_symbol_table(table);

   137       }

   138     }

   139   }

   140   return true;

   141 }

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

   144   // something already went wrong, just give up

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

   146     return false;

   147   }

   148   ElfSymbolTable* symbol_table = m_symbol_tables;

   149   int string_table_index;

   150   int pos_in_string_table;

   151   int off = INT_MAX;

   152   bool found_symbol = false;

   153   while (symbol_table != NULL) {

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

   155       found_symbol = true;

   156     }

   157     symbol_table = symbol_table->m_next;

   158   }

   159   if (!found_symbol) return false;

   161   ElfStringTable* string_table = get_string_table(string_table_index);

   163   if (string_table == NULL) {

   164     m_status = NullDecoder::file_invalid;

   165     return false;

   166   }

   167   if (offset) *offset = off;

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

   170 }

   173 void ElfFile::add_symbol_table(ElfSymbolTable* table) {

   174   if (m_symbol_tables == NULL) {

   175     m_symbol_tables = table;

   176   } else {

   177     table->m_next = m_symbol_tables;

   178     m_symbol_tables = table;

   179   }

   180 }

   182 void ElfFile::add_string_table(ElfStringTable* table) {

   183   if (m_string_tables == NULL) {

   184     m_string_tables = table;

   185   } else {

   186     table->m_next = m_string_tables;

   187     m_string_tables = table;

   188   }

   189 }

   191 ElfStringTable* ElfFile::get_string_table(int index) {

   192   ElfStringTable* p = m_string_tables;

   193   while (p != NULL) {

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

   195     p = p->m_next;

   196   }

   197   return NULL;

   198 }

   200 #ifdef LINUX

   201 bool ElfFile::specifies_noexecstack() {

   202   Elf_Phdr phdr;

   203   if (!m_file)  return true;

   205   if (!fseek(m_file, m_elfHdr.e_phoff, SEEK_SET)) {

   206     for (int index = 0; index < m_elfHdr.e_phnum; index ++) {

   207       if (fread((void*)&phdr, sizeof(Elf_Phdr), 1, m_file) != 1) {

   208         m_status = NullDecoder::file_invalid;

   209         return false;

   210       }

   211       if (phdr.p_type == PT_GNU_STACK) {

   212         if (phdr.p_flags == (PF_R | PF_W))  {

   213           return true;

   214         } else {

   215           return false;

   216         }

   217       }

   218     }

   219   }

   220   return false;

   221 }

   222 #endif

   224 #endif // _WINDOWS

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