// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// 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.

// This file is copied from

// https://github.com/ClickHouse/ClickHouse/blob/master/src/Common/Elf.h

// and modified by Doris

#pragma once

#if defined(__ELF__) && !defined(__FreeBSD__)

#include <elf.h>

#include <link.h>

#include <filesystem>

#include <functional>

#include <optional>

#include <string>

using ElfAddr = ElfW(Addr);

using ElfEhdr = ElfW(Ehdr);

using ElfOff = ElfW(Off);

using ElfPhdr = ElfW(Phdr);

using ElfShdr = ElfW(Shdr);

using ElfNhdr = ElfW(Nhdr);

using ElfSym = ElfW(Sym);

namespace doris {

/** Allow to navigate sections in ELF.

  */

class Elf final {

public:

    struct Section {

        const ElfShdr& header;

        [[nodiscard]] const char* name() const;

        [[nodiscard]] const char* begin() const;

        [[nodiscard]] const char* end() const;

        [[nodiscard]] size_t size() const;

        Section(const ElfShdr& header_, const Elf& elf_);

    private:

        const Elf& elf;

    };

    explicit Elf(const std::string& path);

    ~Elf();

    bool iterateSections(std::function<bool(const Section& section, size_t idx)>&& pred) const;

    std::optional<Section> findSection(

            std::function<bool(const Section& section, size_t idx)>&& pred) const;

    std::optional<Section> findSectionByName(const char* name) const;

    [[nodiscard]] const char* begin() const { return mapped; }

    [[nodiscard]] const char* end() const { return mapped + elf_size; }

    [[nodiscard]] size_t size() const { return elf_size; }

    /// Obtain build id from SHT_NOTE of section headers (fallback to PT_NOTES section of program headers).

    /// Return empty string if does not exist.

    /// The string is returned in binary. Note that "readelf -n ./clickhouse-server" prints it in hex.

    [[nodiscard]] std::string getBuildID() const;

    static std::string getBuildID(const char* nhdr_pos, size_t size);

    /// Hash of the binary for integrity checks.

    [[nodiscard]] std::string getStoredBinaryHash() const;

private:

    int _fd = -1;

    std::filesystem::path _file;

    size_t elf_size;

    char* mapped = nullptr;

    const ElfEhdr* header = nullptr;

    const ElfShdr* section_headers = nullptr;

    const ElfPhdr* program_headers = nullptr;

    const char* section_names = nullptr;

};

} // namespace doris

#endif