DirStream.hxx

#pragma once
 
// C++
#include <exception>
#include <optional>
#include <string_view>
 
// cosmos
#include <cosmos/SysString.hxx>
#include <cosmos/error/ApiError.hxx>
#include <cosmos/error/UsageError.hxx>
#include <cosmos/fs/DirEntry.hxx>
#include <cosmos/fs/DirFD.hxx>
#include <cosmos/fs/filesystem.hxx>
#include <cosmos/utils.hxx>
 
namespace cosmos {
 
 
class COSMOS_API DirStream {
public: // functions
 
        DirStream() = default;
 
 
        explicit DirStream(const DirFD fd) {
                open(fd);
        }
 
        DirStream(const DirFD fd, const SysString subpath) {
                open(fd, subpath);
        }
 
        explicit DirStream(const SysString path) {
                open(path);
        }
 
        // Prevent copying due to the directory stream ownership.
        DirStream(const DirStream&) = delete;
        DirStream& operator=(const DirStream&) = delete;
 
        ~DirStream();
 
 
        void close();
 
 
        void open(const DirFD fd);
 
        void open(const DirFD dir_fd, const SysString subpath);
 
 
        void open(const SysString path, const FollowSymlinks follow_links = FollowSymlinks{false});
 
        auto isOpen() const { return m_stream != nullptr; }
 
 
        DirFD fd() const;
 
 
        DirEntry::DirPos tell() const {
                requireOpenStream("tell");
 
                auto ret = ::telldir(m_stream);
 
                if (ret == -1) {
                        cosmos_throw (ApiError("telldir()"));
                }
 
                return DirEntry::DirPos{ret};
        }
 
 
        void seek(const DirEntry::DirPos pos) {
                requireOpenStream("seek");
 
                ::seekdir(m_stream, to_integral(pos));
        }
 
        void rewind() {
                ::rewinddir(m_stream);
        }
 
 
        std::optional<DirEntry> nextEntry();
 
protected: // functions
 
        void open(const FileNum fd);
 
        void requireOpenStream(const std::string_view context) const {
                if (!isOpen()) {
                        cosmos_throw (UsageError(std::string(context) + " on unassociated DirStream instance"));
                }
        }
 
protected: // data
 
        DIR *m_stream = nullptr;
};
 
} // end ns
 
// make DirIterator available for range based for loops
#include <cosmos/fs/DirIterator.hxx>