serenity/AK/FileStream.h

/*
 * Copyright (c) 2020, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Stream.h>
#ifndef KERNEL
#    include <errno.h>
#    include <stdio.h>

namespace AK {

class InputFileStream : public InputStream {
public:
    explicit InputFileStream(int fd)
        : m_file(fdopen(fd, "r"))
        , m_owned(true)
    {
        if (!m_file)
            set_fatal_error();
    }

    explicit InputFileStream(FILE* fp)
        : m_file(fp)
    {
        if (!m_file)
            set_fatal_error();
    }

    ~InputFileStream()
    {
        if (m_file) {
            fflush(m_file);
            if (m_owned)
                fclose(m_file);
        }
    }

    bool unreliable_eof() const override { return eof(); }
    bool eof() const { return feof(m_file); }

    size_t read(Bytes bytes) override
    {
        if (has_any_error())
            return 0;
        return fread(bytes.data(), sizeof(u8), bytes.size(), m_file);
    }

    bool read_or_error(Bytes bytes) override
    {
        if (has_any_error())
            return false;
        auto size = read(bytes);
        if (size < bytes.size()) {
            set_recoverable_error();
            return false;
        }
        return true;
    }
    bool discard_or_error(size_t count) override
    {
        if (fseek(m_file, count, SEEK_CUR) == 0)
            return true;

        // TODO: Why not ferror(m_file)?
        if (errno != ESPIPE)
            return false;

        char buf[4];
        size_t i = 0;
        while (i < count) {
            auto size = min(count - i, 4ul);
            if (read({ buf, size }) < size) {
                // Can't reset here.
                return false;
            }
            i += size;
        }

        return true;
    }

    bool seek(size_t offset, int whence = SEEK_SET)
    {
        return fseek(m_file, offset, whence) == 0;
    }

    virtual bool handle_any_error() override
    {
        clearerr(m_file);
        return Stream::handle_any_error();
    }

    void make_unbuffered()
    {
        setvbuf(m_file, nullptr, _IONBF, 0);
    }

private:
    FILE* m_file { nullptr };
    bool m_owned { false };
};

class OutputFileStream : public OutputStream {
public:
    explicit OutputFileStream(int fd)
        : m_file(fdopen(fd, "w"))
        , m_owned(true)
    {
        if (!m_file)
            set_fatal_error();
    }

    explicit OutputFileStream(FILE* fp)
        : m_file(fp)
    {
        if (!m_file)
            set_fatal_error();
    }

    ~OutputFileStream()
    {
        if (m_file) {
            fflush(m_file);
            if (m_owned)
                fclose(m_file);
        }
    }

    size_t write(ReadonlyBytes bytes) override
    {
        auto nwritten = fwrite(bytes.data(), sizeof(u8), bytes.size(), m_file);
        m_bytes_written += nwritten;
        return nwritten;
    }

    bool write_or_error(ReadonlyBytes bytes) override
    {
        auto nwritten = write(bytes);
        if (nwritten < bytes.size()) {
            set_recoverable_error();
            return false;
        }
        return true;
    }

    size_t size() const { return m_bytes_written; }

    virtual bool handle_any_error() override
    {
        clearerr(m_file);
        return Stream::handle_any_error();
    }

    void make_unbuffered()
    {
        setvbuf(m_file, nullptr, _IONBF, 0);
    }

private:
    FILE* m_file { nullptr };
    size_t m_bytes_written { 0 };
    bool m_owned { false };
};

}

using AK::InputFileStream;
using AK::OutputFileStream;

#endif