Go 언어의 파일 조작 기능을 배우고 파일 압축, 암호화, 업로드, 다운로드, 압축 해제 기능을 구현합니다.

file, err := os.Create("example.txt")
if err != nil {
    log.Fatal(err)
}
defer file.Close()

data := []byte("Hello, World!")
_, err = file.Write(data)
if err != nil {
    log.Fatal(err)
}

data := make([]byte, 100)
n, err := file.Read(data)
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Read %d bytes: %s
", n, data[:n])

err := os.Remove("example.txt")
if err != nil {
    log.Fatal(err)
}

func compressFile(filename string) {
    zipfilename := filename + ".zip"
    zipFile, err := os.Create(zipfilename)
    if err != nil {
        log.Fatal(err)
    }
    defer zipFile.Close()

    zipWriter := zip.NewWriter(zipFile)
    defer zipWriter.Close()

    file, err := os.Open(filename)
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    fileInfo, err := file.Stat()
    if err != nil {
        log.Fatal(err)
    }

    header, err := zip.FileInfoHeader(fileInfo)
    if err != nil {
        log.Fatal(err)
    }

    writer, err := zipWriter.CreateHeader(header)
    if err != nil {
        log.Fatal(err)
    }

    _, err = io.Copy(writer, file)
    if err != nil {
        log.Fatal(err)
    }
}

func decompressFile(zipfilename string) {
    zipFile, err := zip.OpenReader(zipfilename)
    if err != nil {
        log.Fatal(err)
    }
    defer zipFile.Close()

    for _, file := range zipFile.File {
        rc, err := file.Open()
        if err != nil {
            log.Fatal(err)
        }
        defer rc.Close()

        newFile, err := os.Create(file.Name)
        if err != nil {
            log.Fatal(err)
        }
        defer newFile.Close()

        _, err = io.Copy(newFile, rc)
        if err != nil {
            log.Fatal(err)
        }
    }
}

func encryptFile(filename string, key []byte) {
    inputFile, err := os.Open(filename)
    if err != nil {
        log.Fatal(err)
    }
    defer inputFile.Close()

    outputFile, err := os.Create(filename + ".enc")
    if err != nil {
        log.Fatal(err)
    }
    defer outputFile.Close()

    block, err := aes.NewCipher(key)
    if err != nil {
        log.Fatal(err)
    }

    iv := make([]byte, aes.BlockSize)
    outputFile.Write(iv)

    outputFileWriter := cipher.StreamWriter{
        S: cipher.NewCTR(block, iv),
        W: outputFile,
    }

    _, err = io.Copy(outputFileWriter, inputFile)
    if err != nil {
        log.Fatal(err)
    }
}

func decryptFile(filename string, key []byte) {
    inputFile, err := os.Open(filename + ".enc")
    if err != nil {
        log.Fatal(err)
    }
    defer inputFile.Close()

    outputFile, err := os.Create(filename + ".dec")
    if err != nil {
        log.Fatal(err)
    }
    defer outputFile.Close()

    block, err := aes.NewCipher(key)
    if err != nil {
        log.Fatal(err)
    }

    iv := make([]byte, aes.BlockSize)
    inputFile.Read(iv)

    inputFileReader := cipher.StreamReader{
        S: cipher.NewCTR(block, iv),
        R: inputFile,
    }

    _, err = io.Copy(outputFile, inputFileReader)
    if err != nil {
        log.Fatal(err)
    }
}

func uploadFile(filename string, url string) {
    file, err := os.Open(filename)
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    body := &bytes.Buffer{}
    writer := multipart.NewWriter(body)
    part, err := writer.CreateFormFile("file", filepath.Base(filename))
    if err != nil {
        log.Fatal(err)
    }

    _, err = io.Copy(part, file)
    if err != nil {
        log.Fatal(err)
    }

    writer.Close()

    request, err := http.NewRequest("POST", url, body)
    if err != nil {
        log.Fatal(err)
    }
    request.Header.Add("Content-Type", writer.FormDataContentType())

    client := &http.Client{}
    response, err := client.Do(request)
    if err != nil {
        log.Fatal(err)
    }
    defer response.Body.Close()

    fmt.Println("Upload OK!")
}

func downloadFile(url string, filename string) {
    response, err := http.Get(url)
    if err != nil {
        log.Fatal(err)
    }
    defer response.Body.Close()

    file, err := os.Create(filename)
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    _, err = io.Copy(file, response.Body)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Download OK!")
}