Problem writing file to disk after downloading via FTP

php editor Xinyi, sometimes you may encounter some problems when downloading files through FTP and writing them to disk. This may be due to network connection issues, incorrect permission settings, or insufficient disk space. In this case, we need to carefully check and resolve these issues to ensure that the file can be successfully downloaded and written to the disk. In this article, we'll explore some possible solutions and common errors, and provide some helpful tips to fix them. Whether you are new to using FTP or already familiar with it, this information will be helpful to you.

Question content

The file written to disk is empty, but the reader is not empty. I don't understand what the problem is. I tried using Buffer and then using the String() method and I can confirm that the content is fine, but using the library's Read() method doesn't work.

The library I use is github.com/jlaffaye/ftp

// pullFileByFTP
func pullFileByFTP(fileID, server string, port int64, username, password, path, file string) error {
    // Connect to the server
    client, err := ftp.Dial(fmt.Sprintf("%s:%d", server, port))
    if err != nil {
        return err
    }

    // Log in the server
    err = client.Login(username, password)
    if err != nil {
        return err
    }

    // Retrieve the file
    reader, err := client.Retr(fmt.Sprintf("%s%s", path, file))
    if err != nil {
        return err
    }

    // Read the file
    var srcFile []byte
    _, err = reader.Read(srcFile)
    if err != nil {
        return err
    }

    // Create the destination file
    dstFile, err := os.Create(fmt.Sprintf("%s/%s", shared.TmpDir, fileID))
    if err != nil {
        return fmt.Errorf("Error while creating the destination file : %s", err)
    }
    defer dstFile.Close()

    // Copy the file
    dstFile.Write(srcFile)

    return nil
}

Solution

You are using read and writeError:

var srcFile []byte
_, err = reader.Read(srcFile)

Read puts the bytes read into its argument. Since srcFile is a nil slice, this instructs the reader to read zero bytes. Use ioutil.ReadAll to read all bytes.

The next step is the use of Write. Write(b) Write up to len(b) bytes, but not necessarily all. You must check the return value and call Write repeatedly if necessary.

However, in your case, you only want to connect io.Reader (*Response implements io.Reader) and io.Writer (*os.File). This is what io.Copy is for:

reader, err := client.Retr(path + file)
dstFile, err := ioutil.TempFile("", fileID)

_, err := io.Copy(dstFile, reader)
err := dstFile.Close()

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