| /* |
| * Copyright (c) 1997, 2013, 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/elfFuncDescTable.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_funcDesc_table = 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; |
| } |
| if (shdr.sh_type == SHT_STRTAB) { |
| // string tables |
| 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) { |
| // symbol tables |
| ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(m_file, shdr); |
| if (table == NULL) { |
| m_status = NullDecoder::out_of_memory; |
| return false; |
| } |
| add_symbol_table(table); |
| } |
| } |
| |
| #if defined(PPC64) && !defined(ABI_ELFv2) |
| // Now read the .opd section wich contains the PPC64 function descriptor table. |
| // The .opd section is only available on PPC64 (see for example: |
| // http://refspecs.linuxfoundation.org/LSB_3.1.1/LSB-Core-PPC64/LSB-Core-PPC64/specialsections.html) |
| // so this code should do no harm on other platforms but because of performance reasons we only |
| // execute it on PPC64 platforms. |
| // Notice that we can only find the .opd section after we have successfully read in the string |
| // tables in the previous loop, because we need to query the name of each section which is |
| // contained in one of the string tables (i.e. the one with the index m_elfHdr.e_shstrndx). |
| |
| // Reset the file pointer |
| if (fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) { |
| m_status = NullDecoder::file_invalid; |
| 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; |
| } |
| if (m_elfHdr.e_shstrndx != SHN_UNDEF && shdr.sh_type == SHT_PROGBITS) { |
| ElfStringTable* string_table = get_string_table(m_elfHdr.e_shstrndx); |
| if (string_table == NULL) { |
| m_status = NullDecoder::file_invalid; |
| return false; |
| } |
| char buf[8]; // '8' is enough because we only want to read ".opd" |
| if (string_table->string_at(shdr.sh_name, buf, sizeof(buf)) && !strncmp(".opd", buf, 4)) { |
| m_funcDesc_table = new (std::nothrow) ElfFuncDescTable(m_file, shdr, index); |
| if (m_funcDesc_table == NULL) { |
| m_status = NullDecoder::out_of_memory; |
| return false; |
| } |
| break; |
| } |
| } |
| } |
| #endif |
| |
| } |
| 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, m_funcDesc_table)) { |
| found_symbol = true; |
| break; |
| } |
| 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(const char* filepath) { |
| // Returns true if the elf file is marked NOT to require an executable stack, |
| // or if the file could not be opened. |
| // Returns false if the elf file requires an executable stack, the stack flag |
| // is not set at all, or if the file can not be read. |
| if (filepath == NULL) return true; |
| |
| FILE* file = fopen(filepath, "r"); |
| if (file == NULL) return true; |
| |
| // AARCH64 defaults to noexecstack. All others default to execstack. |
| #ifdef AARCH64 |
| bool result = true; |
| #else |
| bool result = false; |
| #endif |
| |
| // Read file header |
| Elf_Ehdr head; |
| if (fread(&head, sizeof(Elf_Ehdr), 1, file) == 1 && |
| is_elf_file(head) && |
| fseek(file, head.e_phoff, SEEK_SET) == 0) { |
| |
| // Read program header table |
| Elf_Phdr phdr; |
| for (int index = 0; index < head.e_phnum; index ++) { |
| if (fread((void*)&phdr, sizeof(Elf_Phdr), 1, file) != 1) { |
| result = false; |
| break; |
| } |
| if (phdr.p_type == PT_GNU_STACK) { |
| result = (phdr.p_flags == (PF_R | PF_W)); |
| break; |
| } |
| } |
| } |
| fclose(file); |
| return result; |
| } |
| #endif // LINUX |
| |
| #endif // !_WINDOWS && !__APPLE__ |