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 #ifndef _WINDOWS

    28 

    29 #include <string.h>

    30 #include <stdio.h>

    31 #include <limits.h>

    32 

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

    34 #include "utilities/decoder.hpp"

    35 #include "utilities/elfFile.hpp"

    36 #include "utilities/elfStringTable.hpp"

    37 #include "utilities/elfSymbolTable.hpp"

    38 

    39 

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

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

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

    43   m_string_tables = NULL;

    44   m_symbol_tables = NULL;

    45   m_next = NULL;

    46   m_status = Decoder::no_error;

    47 

    48   int len = strlen(filepath) + 1;

    49   m_filepath = NEW_C_HEAP_ARRAY(char, len);

    50   if (m_filepath != NULL) {

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

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

    53     if (m_file != NULL) {

    54       load_tables();

    55     } else {

    56       m_status = Decoder::file_not_found;

    57     }

    58   } else {

    59     m_status = Decoder::out_of_memory;

    60   }

    61 }

    62 

    63 ElfFile::~ElfFile() {

    64   if (m_string_tables != NULL) {

    65     delete m_string_tables;

    66   }

    67 

    68   if (m_symbol_tables != NULL) {

    69     delete m_symbol_tables;

    70   }

    71 

    72   if (m_file != NULL) {

    73     fclose(m_file);

    74   }

    75 

    76   if (m_filepath != NULL) {

    77     FREE_C_HEAP_ARRAY(char, m_filepath);

    78   }

    79 

    80   if (m_next != NULL) {

    81     delete m_next;

    82   }

    83 };

    84 

    85 

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

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

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

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

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

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

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

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

    94 }

    95 

    96 bool ElfFile::load_tables() {

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

    98   assert(m_status == Decoder::no_error, "already in error");

    99 

   100   // read elf file header

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

   102     m_status = Decoder::file_invalid;

   103     return false;

   104   }

   105 

   106   if (!is_elf_file(m_elfHdr)) {

   107     m_status = Decoder::file_invalid;

   108     return false;

   109   }

   110 

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

   112   Elf_Shdr shdr;

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

   114     if (m_status != Decoder::no_error) return false;

   115 

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

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

   118         m_status = Decoder::file_invalid;

   119         return false;

   120       }

   121       // string table

   122       if (shdr.sh_type == SHT_STRTAB) {

   123         ElfStringTable* table = new ElfStringTable(m_file, shdr, index);

   124         if (table == NULL) {

   125           m_status = Decoder::out_of_memory;

   126           return false;

   127         }

   128         add_string_table(table);

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

   130         ElfSymbolTable* table = new ElfSymbolTable(m_file, shdr);

   131         if (table == NULL) {

   132           m_status = Decoder::out_of_memory;

   133           return false;

   134         }

   135         add_symbol_table(table);

   136       }

   137     }

   138   }

   139   return true;

   140 }

   141 

   142 const char* ElfFile::decode(address addr, int* offset) {

   143   // something already went wrong, just give up

   144   if (m_status != Decoder::no_error) {

   145     return NULL;

   146   }

   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 (Decoder::no_error == 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 NULL;

   160 

   161   ElfStringTable* string_table = get_string_table(string_table_index);

   162   if (string_table == NULL) {

   163     m_status = Decoder::file_invalid;

   164     return NULL;

   165   }

   166   if (offset) *offset = off;

   167   return string_table->string_at(pos_in_string_table);

   168 }

   169 

   170 

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

   172   if (m_symbol_tables == NULL) {

   173     m_symbol_tables = table;

   174   } else {

   175     table->m_next = m_symbol_tables;

   176     m_symbol_tables = table;

   177   }

   178 }

   179 

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

   181   if (m_string_tables == NULL) {

   182     m_string_tables = table;

   183   } else {

   184     table->m_next = m_string_tables;

   185     m_string_tables = table;

   186   }

   187 }

   188 

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

   190   ElfStringTable* p = m_string_tables;

   191   while (p != NULL) {

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

   193     p = p->m_next;

   194   }

   195   return NULL;

   196 }

   197 

   198 #endif // _WINDOWS