reader.hpp

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#ifndef OSMIUM_IO_READER_HPP
#define OSMIUM_IO_READER_HPP
 
/*
 
This file is part of Osmium (https://osmcode.org/libosmium).
 
Copyright 2013-2025 Jochen Topf <jochen@topf.org> and others (see README).
 
Boost Software License - Version 1.0 - August 17th, 2003
 
Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:
 
The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
 
*/
 
#include <osmium/io/compression.hpp>
#include <osmium/io/detail/input_format.hpp>
#include <osmium/io/detail/queue_util.hpp>
#include <osmium/io/detail/read_thread.hpp>
#include <osmium/io/detail/read_write.hpp>
#include <osmium/io/error.hpp>
#include <osmium/io/file.hpp>
#include <osmium/io/header.hpp>
#include <osmium/memory/buffer.hpp>
#include <osmium/osm/entity_bits.hpp>
#include <osmium/thread/pool.hpp>
#include <osmium/thread/util.hpp>
#include <osmium/util/config.hpp>
 
#include <cerrno>
#include <cstdlib>
#include <fcntl.h>
#include <future>
#include <memory>
#include <string>
#include <system_error>
#include <thread>
#include <utility>
 
#ifndef _WIN32
# include <sys/wait.h>
#endif
 
#ifndef _MSC_VER
# include <unistd.h>
#endif
 
namespace osmium {
 
    namespace io {
 
        namespace detail {
 
            inline std::size_t get_input_queue_size() noexcept {
                return osmium::config::get_max_queue_size("INPUT", 20);
            }
 
            inline std::size_t get_osmdata_queue_size() noexcept {
                return osmium::config::get_max_queue_size("OSMDATA", 20);
            }
 
        } // namespace detail
 
        class Reader {
 
            // The Reader::read() function reads from a queue of buffers which
            // can contain nested buffers. These nested buffers will be in
            // here, because read() can only return a single unnested buffer.
            osmium::memory::Buffer m_back_buffers;
 
            osmium::io::File m_file;
 
            osmium::thread::Pool* m_pool = nullptr;
 
            std::atomic<std::size_t> m_offset{0};
 
            detail::ParserFactory::create_parser_type m_creator;
 
            enum class status {
                okay   = 0, // normal reading
                error  = 1, // some error occurred while reading
                closed = 2, // close() called
                eof    = 3  // eof of file was reached without error
            } m_status = status::okay;
 
            int m_childpid = 0;
 
            detail::future_string_queue_type m_input_queue;
 
            int m_fd = -1;
 
            std::size_t m_file_size = 0;
 
            std::unique_ptr<osmium::io::Decompressor> m_decompressor;
 
            osmium::io::detail::ReadThreadManager m_read_thread_manager;
 
            detail::future_buffer_queue_type m_osmdata_queue;
            detail::queue_wrapper<osmium::memory::Buffer> m_osmdata_queue_wrapper;
 
            std::future<osmium::io::Header> m_header_future;
            osmium::io::Header m_header;
 
            osmium::thread::thread_handler m_thread;
 
            osmium::osm_entity_bits::type m_read_which_entities = osmium::osm_entity_bits::all;
            osmium::io::read_meta m_read_metadata = osmium::io::read_meta::yes;
            osmium::io::buffers_type m_buffers_kind = osmium::io::buffers_type::any;
 
            void set_option(osmium::thread::Pool& pool) noexcept {
                m_pool = &pool;
            }
 
            void set_option(osmium::osm_entity_bits::type value) noexcept {
                m_read_which_entities = value;
            }
 
            void set_option(osmium::io::read_meta value) noexcept {
                // Ignore this setting if we have a history/change file,
                // because if this is set to "no", we don't see the difference
                // between visible and deleted objects.
                if (!m_file.has_multiple_object_versions()) {
                    m_read_metadata = value;
                }
            }
 
            void set_option(osmium::io::buffers_type value) noexcept {
                m_buffers_kind = value;
            }
 
            // This function will run in a separate thread.
            static void parser_thread(osmium::thread::Pool& pool,
                                      int fd,
                                      const detail::ParserFactory::create_parser_type& creator,
                                      detail::future_string_queue_type& input_queue,
                                      detail::future_buffer_queue_type& osmdata_queue,
                                      std::promise<osmium::io::Header>&& header_promise,
                                      std::atomic<std::size_t>* offset_ptr,
                                      osmium::osm_entity_bits::type read_which_entities,
                                      osmium::io::read_meta read_metadata,
                                      osmium::io::buffers_type buffers_kind,
                                      bool want_buffered_pages_removed) {
                std::promise<osmium::io::Header> promise{std::move(header_promise)};
                osmium::io::detail::parser_arguments args = {
                    pool,
                    fd,
                    input_queue,
                    osmdata_queue,
                    promise,
                    offset_ptr,
                    read_which_entities,
                    read_metadata,
                    buffers_kind,
                    want_buffered_pages_removed};
                creator(args)->parse();
            }
 
#ifndef _WIN32
            static int execute(const std::string& command, const std::string& filename, int* childpid) {
                int pipefd[2];
                if (pipe(pipefd) < 0) {
                    throw std::system_error{errno, std::system_category(), "opening pipe failed"};
                }
                const pid_t pid = fork();
                if (pid < 0) {
                    throw std::system_error{errno, std::system_category(), "fork failed"};
                }
                if (pid == 0) { // child
                    // close all file descriptors except one end of the pipe
                    for (int i = 0; i < 32; ++i) {
                        if (i != pipefd[1]) {
                            ::close(i);
                        }
                    }
                    if (dup2(pipefd[1], 1) < 0) { // put end of pipe as stdout/stdin
                        std::exit(1); // NOLINT(concurrency-mt-unsafe)
                    }
 
                    ::open("/dev/null", O_RDONLY); // stdin
                    ::open("/dev/null", O_WRONLY); // stderr
                    // hack: -g switches off globbing in curl which allows [] to be used in file names
                    // this is important for XAPI URLs
                    // in theory this execute() function could be used for other commands, but it is
                    // only used for curl at the moment, so this is okay.
                    if (::execlp(command.c_str(), command.c_str(), "-g", filename.c_str(), nullptr) < 0) {
                        std::exit(1); // NOLINT(concurrency-mt-unsafe)
                    }
                }
                // parent
                *childpid = pid;
                ::close(pipefd[1]);
                return pipefd[0];
            }
#endif
 
            static int open_input_file_or_url(const std::string& filename, int* childpid) {
                const std::string protocol{filename.substr(0, filename.find_first_of(':'))};
                if (protocol == "http" || protocol == "https" || protocol == "ftp" || protocol == "file") {
#ifndef _WIN32
                    return execute("curl", filename, childpid);
#else
                    throw io_error{"Reading OSM files from the network currently not supported on Windows."};
#endif
                }
                const int fd = osmium::io::detail::open_for_reading(filename);
#if defined(__linux__) || defined(__FreeBSD__)
                if (fd >= 0) {
                    // Tell the kernel we are going to read this file sequentially
                    ::posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
                }
#endif
                return fd;
            }
 
            static std::unique_ptr<Decompressor> make_decompressor(const osmium::io::File& file, int fd, std::atomic<std::size_t>* offset_ptr) {
                const auto& factory = osmium::io::CompressionFactory::instance();
                std::unique_ptr<Decompressor> decompressor;
 
                if (file.buffer()) {
                    decompressor = factory.create_decompressor(file.compression(), file.buffer(), file.buffer_size());
                } else if (file.format() == file_format::pbf) {
                    decompressor = std::unique_ptr<Decompressor>{new DummyDecompressor{}};
                } else {
                    decompressor = factory.create_decompressor(file.compression(), fd);
                }
 
                decompressor->set_offset_ptr(offset_ptr);
                return decompressor;
            }
 
        public:
 
            template <typename... TArgs>
            explicit Reader(const osmium::io::File& file, TArgs&&... args) :
                m_file(file.check()),
                m_creator(detail::ParserFactory::instance().get_creator_function(m_file)),
                m_input_queue(detail::get_input_queue_size(), "raw_input"),
                m_fd(m_file.buffer() ? -1 : open_input_file_or_url(m_file.filename(), &m_childpid)),
                m_file_size(m_fd > 2 ? osmium::file_size(m_fd) : 0),
                m_decompressor(make_decompressor(m_file, m_fd, &m_offset)),
                m_read_thread_manager(*m_decompressor, m_input_queue),
                m_osmdata_queue(detail::get_osmdata_queue_size(), "parser_results"),
                m_osmdata_queue_wrapper(m_osmdata_queue) {
 
                (void)std::initializer_list<int>{(set_option(std::forward<TArgs>(args)), 0)...};
 
                if (!m_pool) {
                    m_pool = &thread::Pool::default_instance();
                }
 
                std::promise<osmium::io::Header> header_promise;
                m_header_future = header_promise.get_future();
 
                const auto cpc = osmium::config::clean_page_cache_after_read();
                if (cpc >= 0) {
                    m_decompressor->set_want_buffered_pages_removed(true);
                }
 
                const int fd_for_parser = m_decompressor->is_real() ? -1 : m_fd;
                m_thread = osmium::thread::thread_handler{parser_thread, std::ref(*m_pool), fd_for_parser, std::ref(m_creator),
                                                          std::ref(m_input_queue), std::ref(m_osmdata_queue),
                                                          std::move(header_promise), &m_offset, m_read_which_entities,
                                                          m_read_metadata, m_buffers_kind,
                                                          m_decompressor->want_buffered_pages_removed()};
            }
 
            template <typename... TArgs>
            explicit Reader(const std::string& filename, TArgs&&... args) :
                Reader(osmium::io::File(filename), std::forward<TArgs>(args)...) {
            }
 
            template <typename... TArgs>
            explicit Reader(const char* filename, TArgs&&... args) :
                Reader(osmium::io::File(filename), std::forward<TArgs>(args)...) {
            }
 
            Reader(const Reader&) = delete;
            Reader& operator=(const Reader&) = delete;
 
            Reader(Reader&&) = delete;
            Reader& operator=(Reader&&) = delete;
 
            ~Reader() noexcept {
                try {
                    close();
                } catch (...) { // NOLINT(bugprone-empty-catch)
                    // Ignore any exceptions because destructor must not throw.
                }
            }
 
            void close() {
                m_status = status::closed;
 
                m_read_thread_manager.stop();
 
                m_osmdata_queue_wrapper.shutdown();
 
                try {
                    m_read_thread_manager.close();
                } catch (...) { // NOLINT(bugprone-empty-catch)
                    // Ignore any exceptions.
                }
 
#ifndef _WIN32
                if (m_childpid) {
                    int status = 0;
                    const pid_t pid = ::waitpid(m_childpid, &status, 0);
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
                    if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { // NOLINT(hicpp-signed-bitwise)
                        throw std::system_error{errno, std::system_category(), "subprocess returned error"};
                    }
#pragma GCC diagnostic pop
                    m_childpid = 0;
                }
#endif
            }
 
            osmium::io::Header header() {
                if (m_status == status::error) {
                    throw io_error{"Can not get header from reader when in status 'error'"};
                }
 
                try {
                    if (m_header_future.valid()) {
                        m_header = m_header_future.get();
                    }
                } catch (...) {
                    close();
                    m_status = status::error;
                    throw;
                }
 
                return m_header;
            }
 
            osmium::memory::Buffer read() {
                osmium::memory::Buffer buffer;
 
                // If there are buffers on the stack, return those first.
                if (m_back_buffers) {
                    if (m_back_buffers.has_nested_buffers()) {
                        buffer = std::move(*m_back_buffers.get_last_nested());
                    } else {
                        buffer = std::move(m_back_buffers);
                        m_back_buffers = osmium::memory::Buffer{};
                    }
                    return buffer;
                }
 
                if (m_status != status::okay) {
                    throw io_error{"Can not read from reader when in status 'closed', 'eof', or 'error'"};
                }
 
                if (m_read_which_entities == osmium::osm_entity_bits::nothing) {
                    m_status = status::eof;
                    return buffer;
                }
 
                try {
                    // m_input_format.read() can return an invalid buffer to signal EOF,
                    // or a valid buffer with or without data. A valid buffer
                    // without data is not an error, it just means we have to
                    // keep getting the next buffer until there is one with data.
                    while (true) {
                        buffer = m_osmdata_queue_wrapper.pop();
                        if (detail::at_end_of_data(buffer)) {
                            m_status = status::eof;
                            m_read_thread_manager.close();
                            return buffer;
                        }
                        if (buffer.has_nested_buffers()) {
                            m_back_buffers = std::move(buffer);
                            buffer = std::move(*m_back_buffers.get_last_nested());
                        }
                        if (buffer.committed() > 0) {
                            return buffer;
                        }
                    }
                } catch (...) {
                    close();
                    m_status = status::error;
                    throw;
                }
            }
 
            bool eof() const {
                return m_status == status::eof || m_status == status::closed;
            }
 
            std::size_t file_size() const noexcept {
                return m_file_size;
            }
 
            std::size_t offset() const noexcept {
                return m_offset;
            }
 
        }; // class Reader
 
        template <typename... TArgs>
        osmium::memory::Buffer read_file(TArgs&&... args) {
            osmium::memory::Buffer buffer{1024UL * 1024UL, osmium::memory::Buffer::auto_grow::yes};
 
            Reader reader{std::forward<TArgs>(args)...};
            while (auto read_buffer = reader.read()) {
                buffer.add_buffer(read_buffer);
                buffer.commit();
            }
 
            return buffer;
        }
 
    } // namespace io
 
} // namespace osmium
 
#endif // OSMIUM_IO_READER_HPP