/*
* Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#if !defined(_WINDOWS) && !defined(__APPLE__)
#include <string.h>
#include <stdio.h>
#include <limits.h>
#include <new>
#include "memory/allocation.inline.hpp"
#include "utilities/decoder.hpp"
#include "utilities/elfFile.hpp"
#include "utilities/elfStringTable.hpp"
#include "utilities/elfSymbolTable.hpp"
ElfFile::ElfFile(const char* filepath) {
assert(filepath, "null file path");
memset(&m_elfHdr, 0, sizeof(m_elfHdr));
m_string_tables = NULL;
m_symbol_tables = NULL;
m_next = NULL;
m_status = NullDecoder::no_error;
int len = strlen(filepath) + 1;
m_filepath = (const char*)os::malloc(len * sizeof(char), mtInternal);
if (m_filepath != NULL) {
strcpy((char*)m_filepath, filepath);
m_file = fopen(filepath, "r");
if (m_file != NULL) {
load_tables();
} else {
m_status = NullDecoder::file_not_found;
}
} else {
m_status = NullDecoder::out_of_memory;
}
}
ElfFile::~ElfFile() {
if (m_string_tables != NULL) {
delete m_string_tables;
}
if (m_symbol_tables != NULL) {
delete m_symbol_tables;
}
if (m_file != NULL) {
fclose(m_file);
}
if (m_filepath != NULL) {
os::free((void*)m_filepath);
}
if (m_next != NULL) {
delete m_next;
}
};
//Check elf header to ensure the file is valid.
bool ElfFile::is_elf_file(Elf_Ehdr& hdr) {
return (ELFMAG0 == hdr.e_ident[EI_MAG0] &&
ELFMAG1 == hdr.e_ident[EI_MAG1] &&
ELFMAG2 == hdr.e_ident[EI_MAG2] &&
ELFMAG3 == hdr.e_ident[EI_MAG3] &&
ELFCLASSNONE != hdr.e_ident[EI_CLASS] &&
ELFDATANONE != hdr.e_ident[EI_DATA]);
}
bool ElfFile::load_tables() {
assert(m_file, "file not open");
assert(!NullDecoder::is_error(m_status), "already in error");
// read elf file header
if (fread(&m_elfHdr, sizeof(m_elfHdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
if (!is_elf_file(m_elfHdr)) {
m_status = NullDecoder::file_invalid;
return false;
}
// walk elf file's section headers, and load string tables
Elf_Shdr shdr;
if (!fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
if (NullDecoder::is_error(m_status)) return false;
for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
// string table
if (shdr.sh_type == SHT_STRTAB) {
ElfStringTable* table = new (std::nothrow) ElfStringTable(m_file, shdr, index);
if (table == NULL) {
m_status = NullDecoder::out_of_memory;
return false;
}
add_string_table(table);
} else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {
ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(m_file, shdr);
if (table == NULL) {
m_status = NullDecoder::out_of_memory;
return false;
}
add_symbol_table(table);
}
}
}
return true;
}
bool ElfFile::decode(address addr, char* buf, int buflen, int* offset) {
// something already went wrong, just give up
if (NullDecoder::is_error(m_status)) {
return false;
}
ElfSymbolTable* symbol_table = m_symbol_tables;
int string_table_index;
int pos_in_string_table;
int off = INT_MAX;
bool found_symbol = false;
while (symbol_table != NULL) {
if (symbol_table->lookup(addr, &string_table_index, &pos_in_string_table, &off)) {
found_symbol = true;
}
symbol_table = symbol_table->m_next;
}
if (!found_symbol) return false;
ElfStringTable* string_table = get_string_table(string_table_index);
if (string_table == NULL) {
m_status = NullDecoder::file_invalid;
return false;
}
if (offset) *offset = off;
return string_table->string_at(pos_in_string_table, buf, buflen);
}
void ElfFile::add_symbol_table(ElfSymbolTable* table) {
if (m_symbol_tables == NULL) {
m_symbol_tables = table;
} else {
table->m_next = m_symbol_tables;
m_symbol_tables = table;
}
}
void ElfFile::add_string_table(ElfStringTable* table) {
if (m_string_tables == NULL) {
m_string_tables = table;
} else {
table->m_next = m_string_tables;
m_string_tables = table;
}
}
ElfStringTable* ElfFile::get_string_table(int index) {
ElfStringTable* p = m_string_tables;
while (p != NULL) {
if (p->index() == index) return p;
p = p->m_next;
}
return NULL;
}
#ifdef LINUX
bool ElfFile::specifies_noexecstack() {
Elf_Phdr phdr;
if (!m_file) return true;
if (!fseek(m_file, m_elfHdr.e_phoff, SEEK_SET)) {
for (int index = 0; index < m_elfHdr.e_phnum; index ++) {
if (fread((void*)&phdr, sizeof(Elf_Phdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
if (phdr.p_type == PT_GNU_STACK) {
if (phdr.p_flags == (PF_R | PF_W)) {
return true;
} else {
return false;
}
}
}
}
return false;
}
#endif
#endif // _WINDOWS