PHP implements upload restrictions on file upload and download

Client restrictions

The code is as follows:

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no"> 
 <meta name="format-detection" content="telephone=no" /> 
<title>文件上传(客户端限制)</title>
<meta charset="utf-8" />
</head>
<body>
<form action="upload2.php" method="post" enctype="multipart/form-data">
<input type="hidden" name="MAX_FILE_SIZE" value="101321" />
请选择您要上传的文件：
<input type="file" name="myFile" accept="image/jpeg,image/gif,text/html"/><br/>
<input type="submit" value="上传"/>
</form>
</body>
</html>

The input attributes are used here to limit the size and type of uploaded files. But I personally feel that

1.html code is "visible"

2. It often doesn't work (I haven't found the reason, but because of the first one I also want to give up on it, just know it.

##Server Side Limitations

Main Limitations Size and Type , and then there is the method.

<?php
header('content-type:text/html;charset=utf-8');
//接受文件，临时文件信息
$fileinfo=$_FILES["myFile"];//降维操作
$filename=$fileinfo["name"];
$tmp_name=$fileinfo["tmp_name"];
$size=$fileinfo["size"];
$error=$fileinfo["error"];
$type=$fileinfo["type"];
 
//服务器端设定限制
$maxsize=10485760;//10M,10*1024*1024
$allowExt=array('jpeg','jpg','png','tif');//允许上传的文件类型（拓展名
$ext=pathinfo($filename,PATHINFO_EXTENSION);//提取上传文件的拓展名
 
//目标存放文件夹
$path="uploads";
if (!file_exists($path)) {  //当目录不存在，就创建目录
  mkdir($path,0777,true);//创建目录
  chmod($path, 0777);//改变文件模式,所有人都有执行权限、写权限、度权限
}
//得到唯一的文件名！防止因为文件名相同而产生覆盖
$uniName=md5(uniqid(microtime(true),true)).".$ext";//md5加密，uniqid产生唯一id，microtime做前缀
//目标存放文件地址
$destination=$path."/".$uniName;
//当文件上传成功，存入临时文件夹，服务器端开始判断
if ($error===0) {
  if ($size>$maxsize) {
    exit("上传文件过大！");
  }
  if (!in_array($ext, $allowExt)) {
    exit("非法文件类型");
  }
  if (!is_uploaded_file($tmp_name)) {
    exit("上传方式有误，请使用post方式");
  }
  //判断是否为真实图片（防止伪装成图片的病毒一类的
  if (!getimagesize($tmp_name)) {//getimagesize真实返回数组，否则返回false
    exit("不是真正的图片类型");
  }
  //move_uploaded_file($tmp_name, "uploads/".$filename);
  if (@move_uploaded_file($tmp_name, $destination)) {//@错误抑制符，不让用户看到警告
    echo "文件".$filename."上传成功!";
  }else{
    echo "文件".$filename."上传失败!";
  } 
}else{
  switch ($error){
    case 1:
      echo "超过了上传文件的最大值，请上传2M以下文件";
      break;
    case 2:
      echo "上传文件过多，请一次上传20个及以下文件！";
      break;
    case 3:
      echo "文件并未完全上传，请再次尝试！";
      break;
    case 4:
      echo "未选择上传文件！";
      break;
    case 7:
      echo "没有临时文件夹";
      break;
  }
}

Here, the specific implementation is commented, and you can actually try it yourself, which is very interesting

Continuing Learning

new file

<!DOCTYPE html> <html> <head> <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no"> <meta name="format-detection" content="telephone=no" /> <title>文件上传(客户端限制)</title> <meta charset="utf-8" /> </head> <body> <form action="upload2.php" method="post" enctype="multipart/form-data"> <input type="hidden" name="MAX_FILE_SIZE" value="101321" /> 请选择您要上传的文件： <input type="file" name="myFile" accept="image/jpeg,image/gif,text/html"/><br/> <input type="submit" value="上传"/> </form> </body> </html>

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PHP implements upload restrictions on file upload and download

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