How to accurately determine the file type in php without using the extension

This article mainly introduces the method for PHP to accurately determine the file type without using the extension. It involves the finfo_file method in PHP and the related operating skills of binary stream for file types. Friends in need can refer to this article

The example describes how PHP can accurately determine the file type without using the extension. Share it with everyone for your reference, the details are as follows:

The first method

Through php's finfo_file()

$handle=finfo_open(FILEINFO_MIME_TYPE);//This function opens a magic database and returns its resource. 
$fileInfo=finfo_file($handle,'./test.txt');// Return information about a file
finfo_close($handle);
print_r($fileInfo);
echo '==========="\n"';

Also

finfo_buffer: Return information about a string buffer
finfo_close: Close fileinfo resource
mime_content_type:Detect MIME Content-type for a file (deprecated)

Second method

Get file content through binary stream

$fp=fopen('test.txt','r')///实际是image/png
$bin = fread($fp, 2); //只读2字节
fclose($fp);
$str_info = @unpack(“C2chars”, $bin);//Unpack data from binary string
$type_code = intval($str_info['chars1'].$str_info['chars2']);// Get the integer value of a variable
$file_type = ”;
switch ($type_code) {
case 7790:
$file_type = 'exe';
break;
case 7784:
$file_type = 'midi';
break;
case 8075:
$file_type = 'zip';
break;
case 8297:
$file_type = 'rar';
break;
case 255216:
$file_type = 'jpg';
break;
case 7173:
$file_type = 'gif';
break;
case 6677:
$file_type = 'bmp';
break;
case 13780:
$file_type = 'png';
break;
default:
$file_type = 'unknown';
break;
}

The above is the entire content of this article, I hope it will be helpful to everyone's study.

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