<form method="post" name="update_form" action="php/editpost" enctype="multipart/form-data">

    <div class="form-group">
        <label for="img_upload">Select image</label>
        <input type="file" name="img_upload" id="img_upload" class="form-control">
    </div>

    <div class="form-group">
        <input class="btn btn-success btn-lg" type="submit" value="Update" name="edit_submit" id="edit_submit">
    </div>

</form>

if ($_FILES["img_upload"]["name"]) {

    $target_dir = "uploads/";
    $target_file = $target_dir . basename($_FILES["img_upload"]["name"]);
    $imgsrc = $target_file;
    $uploadOk = 1;
    $imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);

    // Check if image file is a actual image and square
    $check = getimagesize($_FILES["img_upload"]["tmp_name"]);
    if($check !== false) {
        $width = $check[0];
        $height = $check[1];
        if ($width != $height) {
            $error = $error."<br />- The image is not square, please crop it and try again.";
            $uploadOk = 0;
        }
    } else {
        $error = $error."<br />- File is not an image.";
        $uploadOk = 0;
    }

    // Check if file already exists
    if (file_exists($target_file)) {
        chmod($target_file,0755); // Change the file permissions
        unlink($target_file); // remove the file
    }

    // Check file size
    if ($_FILES["img_upload"]["size"] > 1000000) {
        $error = $error."<br />- Your image is too large.";
        $uploadOk = 0;
    }

    // Allow certain file formats
    if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg") {
        $error = $error."<br>- Only JPG, JPEG & PNG images are allowed.";
        $uploadOk = 0;
    }

    // Check if $uploadOk is set to 0 by an error
    if ($uploadOk == 0) {
        $fail .= "There were error(s) while uploading the image:<br />".$error;
    }

    // if everything is ok, try to upload file
    else {

        if (move_uploaded_file($_FILES["img_upload"]["tmp_name"], $target_file)) {

            $sql = mysqli_query($link,"UPDATE `posts` SET `imagesrc`='$imgsrc' WHERE `postid`='$postid' LIMIT 1");

            if ($sql) {
                $success .= '- Image updated successfully.<br />';
            }  else {
                $fail .= "- Failed to update the image.<br />";
            }
        }
    }
}

header("location:../admincontrol?result_s=".urlencode($success)."&result_f=".urlencode($fail));
exit();