| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // -*- mode: C++ -*- |
| // |
| // Copyright 2022 Google LLC |
| // |
| // Licensed under the Apache License v2.0 with LLVM Exceptions (the |
| // "License"); you may not use this file except in compliance with the |
| // License. You may obtain a copy of the License at |
| // |
| // https://llvm.org/LICENSE.txt |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| // Author: Aleksei Vetrov |
| |
| #ifndef STG_DWARF_H_ |
| #define STG_DWARF_H_ |
| |
| #include <elf.h> |
| #include <elfutils/libdw.h> |
| |
| #include <cstddef> |
| #include <memory> |
| #include <string> |
| #include <vector> |
| |
| #include "file_descriptor.h" |
| |
| namespace stg { |
| namespace dwarf { |
| |
| // C++ wrapper over Dwarf_Die, providing interface for its various properties. |
| struct Entry { |
| // All methods in libdw take Dwarf_Die by non-const pointer as libdw caches |
| // in it a link to the associated abbreviation table. Updating this link is |
| // not thread-safe and so we cannot, for example, hold a std::shared_ptr to a |
| // heap-allocated Dwarf_Die. |
| // |
| // The only options left are holding a std::unique_ptr or storing a value. |
| // Unique pointers will add one more level of indirection to a hot path. |
| // So we choose to store Dwarf_Die values. |
| // |
| // Each Entry only contains references to DWARF file memory and is fairly |
| // small (32 bytes), so copies can be easily made if necessary. However, |
| // within one thread it is preferable to pass it by reference. |
| Dwarf_Die die{}; |
| |
| // Get list of direct descendants of an entry in the DWARF tree. |
| std::vector<Entry> GetChildren(); |
| |
| // All getters are non-const as libdw may need to modify Dwarf_Die. |
| int GetTag(); |
| }; |
| |
| // C++ wrapper over libdw (DWARF library). |
| // |
| // Creates a "Dwarf" object from an ELF file or a memory and controls the life |
| // cycle of the created objects. |
| class Handler { |
| public: |
| explicit Handler(const std::string& path); |
| Handler(char* data, size_t size); |
| |
| std::vector<Entry> GetCompilationUnits(); |
| |
| private: |
| struct ElfDeleter { |
| void operator()(Elf* elf) { elf_end(elf); } |
| }; |
| |
| struct DwarfDeleter { |
| void operator()(Dwarf* dwarf) { dwarf_end(dwarf); } |
| }; |
| |
| void InitialiseDwarf(); |
| |
| // The order of the following three fields is important because Elf uses a |
| // value from FileDescriptor without owning it, and Dwarf uses an Elf*. |
| FileDescriptor fd_; |
| std::unique_ptr<Elf, ElfDeleter> elf_; |
| std::unique_ptr<Dwarf, DwarfDeleter> dwarf_; |
| }; |
| |
| } // namespace dwarf |
| } // namespace stg |
| |
| #endif // STG_DWARF_H_ |