/thirdparty/breakpad/common/linux/elf_symbols_to_module.cc
http://github.com/tomahawk-player/tomahawk · C++ · 168 lines · 87 code · 22 blank · 59 comment · 14 complexity · 564e4ccc43e830d6a2ee42a69a545847 MD5 · raw file
- // -*- mode: c++ -*-
- // Copyright (c) 2011 Google Inc. All Rights Reserved.
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions are
- // met:
- //
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above
- // copyright notice, this list of conditions and the following disclaimer
- // in the documentation and/or other materials provided with the
- // distribution.
- // * Neither the name of Google Inc. nor the names of its
- // contributors may be used to endorse or promote products derived from
- // this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- // Original author: Ted Mielczarek <ted.mielczarek@gmail.com>
- #include "common/linux/elf_symbols_to_module.h"
- #include <elf.h>
- #include <string.h>
- #include "common/byte_cursor.h"
- #include "common/module.h"
- namespace google_breakpad {
- class ELFSymbolIterator {
- public:
- // The contents of an ELF symbol, adjusted for the host's endianness,
- // word size, and so on. Corresponds to the data in Elf32_Sym / Elf64_Sym.
- struct Symbol {
- // True if this iterator has reached the end of the symbol array. When
- // this is set, the other members of this structure are not valid.
- bool at_end;
- // The number of this symbol within the list.
- size_t index;
- // The current symbol's name offset. This is the offset within the
- // string table.
- size_t name_offset;
- // The current symbol's value, size, info and shndx fields.
- uint64_t value;
- uint64_t size;
- unsigned char info;
- uint16_t shndx;
- };
- // Create an ELFSymbolIterator walking the symbols in BUFFER. Treat the
- // symbols as big-endian if BIG_ENDIAN is true, as little-endian
- // otherwise. Assume each symbol has a 'value' field whose size is
- // VALUE_SIZE.
- //
- ELFSymbolIterator(const ByteBuffer *buffer, bool big_endian,
- size_t value_size)
- : value_size_(value_size), cursor_(buffer, big_endian) {
- // Actually, weird sizes could be handled just fine, but they're
- // probably mistakes --- expressed in bits, say.
- assert(value_size == 4 || value_size == 8);
- symbol_.index = 0;
- Fetch();
- }
- // Move to the next symbol. This function's behavior is undefined if
- // at_end() is true when it is called.
- ELFSymbolIterator &operator++() { Fetch(); symbol_.index++; return *this; }
- // Dereferencing this iterator produces a reference to an Symbol structure
- // that holds the current symbol's values. The symbol is owned by this
- // SymbolIterator, and will be invalidated at the next call to operator++.
- const Symbol &operator*() const { return symbol_; }
- const Symbol *operator->() const { return &symbol_; }
- private:
- // Read the symbol at cursor_, and set symbol_ appropriately.
- void Fetch() {
- // Elf32_Sym and Elf64_Sym have different layouts.
- unsigned char other;
- if (value_size_ == 4) {
- // Elf32_Sym
- cursor_
- .Read(4, false, &symbol_.name_offset)
- .Read(4, false, &symbol_.value)
- .Read(4, false, &symbol_.size)
- .Read(1, false, &symbol_.info)
- .Read(1, false, &other)
- .Read(2, false, &symbol_.shndx);
- } else {
- // Elf64_Sym
- cursor_
- .Read(4, false, &symbol_.name_offset)
- .Read(1, false, &symbol_.info)
- .Read(1, false, &other)
- .Read(2, false, &symbol_.shndx)
- .Read(8, false, &symbol_.value)
- .Read(8, false, &symbol_.size);
- }
- symbol_.at_end = !cursor_;
- }
- // The size of symbols' value field, in bytes.
- size_t value_size_;
- // A byte cursor traversing buffer_.
- ByteCursor cursor_;
- // Values for the symbol this iterator refers to.
- Symbol symbol_;
- };
- const char *SymbolString(ptrdiff_t offset, ByteBuffer& strings) {
- if (offset < 0 || (size_t) offset >= strings.Size()) {
- // Return the null string.
- offset = 0;
- }
- return reinterpret_cast<const char *>(strings.start + offset);
- }
- bool ELFSymbolsToModule(const uint8_t *symtab_section,
- size_t symtab_size,
- const uint8_t *string_section,
- size_t string_size,
- const bool big_endian,
- size_t value_size,
- Module *module) {
- ByteBuffer symbols(symtab_section, symtab_size);
- // Ensure that the string section is null-terminated.
- if (string_section[string_size - 1] != '\0') {
- const void* null_terminator = memrchr(string_section, '\0', string_size);
- string_size = reinterpret_cast<const uint8_t*>(null_terminator)
- - string_section;
- }
- ByteBuffer strings(string_section, string_size);
- // The iterator walking the symbol table.
- ELFSymbolIterator iterator(&symbols, big_endian, value_size);
- while(!iterator->at_end) {
- if (ELF32_ST_TYPE(iterator->info) == STT_FUNC &&
- iterator->shndx != SHN_UNDEF) {
- Module::Extern *ext = new Module::Extern;
- ext->name = SymbolString(iterator->name_offset, strings);
- ext->address = iterator->value;
- module->AddExtern(ext);
- }
- ++iterator;
- }
- return true;
- }
- } // namespace google_breakpad