Blob size is 1 KB when I download it from my database

Question

When I download a blob image from my database its size is 1 KB. When I open the .png file itself, the image is not appearing. The image size appears in my MySQL database table. I couldn't figure out why it downloads an empty file from my database while the name and filetype are showing up correctly.

My table columns

Everything seems to be correct with name, filetype, and size.

File Upload.php

<?php
    require('config.php');
    session_start();
    if(isset($_POST['save']))
    {
        $target_dir = "upload/img/";

        $filename = explode('.', $_FILES['image']['name']);
        $ext = $filename[1];
        $imgname = time() . '.' . $ext;
        $target_file = $target_dir . $imgname;

        $uploadOk = 1;
        $imageFileType = pathinfo($target_file, PATHINFO_EXTENSION);
        // Check if image file is a actual image or fake image
        $check = getimagesize($_FILES["image"]["tmp_name"]);
        if($check !== false) {
            $text = "File is an image - " . $check["mime"] . ".";
            $uploadOk = 1;
        } else {
            $text = "File is not an image.";
            $uploadOk = 0;
        }
        // Check if file already exists
        if(file_exists($target_file)) {
            $text = "Sorry, file already exists.";
            $uploadOk = 0;
        }
        // Check file size
        if($_FILES["image"]["size"] > 2000000) {
            $text = "Sorry, your file is too large.";
            $uploadOk = 0;
        }
        // Allow certain file formats
        if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg" &&
           $imageFileType != "gif" && $imageFileType != "bmp" ) {

            echo "Sorry, only JPG, JPEG, PNG, GIF & BMP files are allowed.";
            $uploadOk = 0;
        }
        // Check if $uploadOk is set to 0 by an error
        if($uploadOk == 0) {
            $_SESSION["error"] = $text;
            header("Location:index.php?id=$id"); /* Redirect browser */
            exit();

        // If everything is OK, try to upload the file
        }else {
            if (move_uploaded_file($_FILES["image"]["tmp_name"], $target_file)) {
                $path = $imgname;
                $finfo = new finfo();
                $array = explode('.', $_FILES['image']['name']);
                $extension = end($array);
                $filesize = $_FILES["image"]["size"];

                $conn->query("INSERT INTO images (image,name,filetype,size) VALUES ('$path','$path','$extension','$filesize')");
                $_SESSION["Success"] = 'Upload success';
                header("Location:index.php"); /* Redirect browser */
                exit();
            } else {
                $_SESSION["err"] = $text;
                header("Location:index.php"); /* Redirect browser */
                exit();
            }
        }
    }
?>

File Download.php

<?php
    // Include configuration file
    require_once 'config.php';

    $id = $_GET["id"];
    $sql = "select * from images where id=$id "; // 1
    $res = $conn->query($sql);
    while($row = $res->fetch_assoc())
    {
        $image = $row['image'];
        $name = $row['name'];
        $type = $row['filetype'];
        $size =  $row['size'];
    }

    header("Content-type: " . $type);
    header('Content-Disposition: attachment; filename="' . $name . '"');
    header("Content-Transfer-Encoding: binary");
    header('Expires: 0');
    header('Pragma: no-cache');
    header("Content-Length: " . $size);

    echo $image;
    exit();
?>

Answer 1

Your screenshot of the database shows your image blob being 14 bytes only. This is simply the name of the file:

 $conn->query("INSERT INTO images (image, name,filetype,size)
               VALUES ('$path','$path','$extension','$filesize')");

Here is your problem. You are inserting the file name as the file data.

Simply replace your first instance of $path with the contents of the file:

 $fileData = file_get_contents($target_file);
 $conn->query("INSERT INTO images (image, name,filetype,size)
               VALUES ('$fileData','$path','$extension','$filesize')");

---

Stop using content-length in you header. It is fraught with problems when using PHP with downloading files. Just don't use it and let the browser accept as much data as the server will give it.

The issue is the way PHP reads the filesize on some systems, and passes that data to the header, but the header is accepting either filesizes which are a bit larger (~5%) due to how the diskspace is read by different programs, or totally different due to the server auto-compressing the file in transfer (gzip).

(For all intents and purposes, from the viewpoint of the web server/browser, the blob data is a file.)

---

As referenced by Shadow, your content type header is also incorrect.

 header("Content-type: " . $type); // Wrong $type.

It should be a recognised MIME type such as image/jpeg, so $extension = end($array); should be replaced by something such as mime_content_type():

 $extension = mime_content_type($target_file)