PHP detects file types based on file header _php Tutorial

File signatures are usually in the header of the file, and if you view the file in hexadecimal, you can see some signature information for the file. If you use Uestudio to view a zip-formatted file in 16, the file content header has 4 b 03 04 hex information. In the same way JPG file status has FF D8 ff E0 xx xx 4 A 46 such hexadecimal information, in fact this hexadecimal is to represent some special note.

How does PHP validate file types? Let's look at a simple method:

function Checkfiletype ($fileName) {          $file = fopen ($fileName, "RB");          $bin = Fread ($file, 2); Read-only 2          -byte fclose ($file);  c is an unsigned integer, the net search is C, signed integer, this will produce negative judgment         $strInfo  = @unpack ("C2chars", $bin);         $typeCode = Intval ($strInfo [' chars1 ']. $strInfo [' chars2 ']);          $fileType = ";  Switch ($typeCode) {case ' 255216 ': return $typeCode. ' : ' .' JPG '; Break;case ' 7173 ': return $typeCode. ' : ' .' GIF '; Break;case ' 13780 ': return $typeCode. ' : ' .' PNG '; Break;case ' 6677 ': return $typeCode. ' : ' .' BMP '; Break;case ' 7790 ': return $typeCode. ' : ' .' EXE '; break;case ' 7784 ': return $typeCode. ' : ' .' Midi '; Break;case ' 8297 ': return $typeCode. ' : ' .' RAR '; Break;default:return $typeCode. ' : ' .' Unknown '; break;} return $typeCode;    } $file _name = ' 11.doc '; Echo checkfiletype ($file _name);

Down to provide a class implementation:

/* Get file type by filename * * @author chengmo qq:8292669* * @copyright Http://www.cnblogs.com/chengmo 2010-10-17 * @version 0.1 *$ Filename= "D:/1.png"; Echo Cfiletypecheck::getfiletype ($filename);    Print: PNG */class cfiletypecheck{private static $_typelist=array ();    private static $CheckClass =null;    Private function __construct ($filename) {self::$_typelist= $this->gettypelist (); }/** * Processing file type mapping Relationship table * * * @param string $filename file type * @return string file type, not found returned: other */priv        Ate function _getfiletype ($filename) {$filetype = "other";        if (!file_exists ($filename)) throw new Exception ("No found file!");        $file = @fopen ($filename, "RB");        if (! $file) throw new Exception ("File refuse!"); $bin = Fread ($file, 15);        Read-only 15 bytes each different file type, header information is not the same.                 Fclose ($file);        $typelist =self::$_typelist; foreach ($typelist as $v) {$blen =strlen (Pack ("h*", $v [0])),//Get header Tag bytes $tbin =substr ($bin, 0, IntvAl ($blen));                You need to compare the file header length if (strtolower ($v [0]) ==strtolower (Array_shift (Unpack ("h*", $tbin))) {            return $v [1];    }} return $filetype;     }/** * Get file header with file type mapping table * * * @return array array (' key ', value) ...)        */Public Function gettypelist () {return Array (array ("Ffd8ffe1", "jpg"), Array ("89504E47", "PNG"),        Array ("47494638", "gif"), Array ("49492a00", "TIF"), Array ("424D", "BMP"), Array ("41433130", "DWG"), Array ("38425053", "PSD"), Array ("7b5c727466", "RTF"), Array ("3C3F786D6C", "xml"), Array ("68746d6c3e "," HTML "), Array (" 44656c69766572792d646174 "," EML "), Array (" cfad12fec5fd746f "," dbx "), Array (" 2142444E "        , "PST"), Array ("D0cf11e0", "Xls/doc"), Array ("5374616e64617264204a", "MDB"), Array ("FF575043", "WPD"),     Array ("252150532d41646f6265", "Eps/ps"), Array ("255044462d312e", "PDF"),   Array ("E3828596", "PWL"), Array ("504b0304", "zip"), Array ("52617221", "rar"), Array ("57415645", "wav") , Array ("41564920", "avi"), Array ("2E7261FD", "Ram"), Array ("2e524d46", "rm"), Array ("000001BA", " MPG "), Array (" 000001B3 "," mpg "), Array (" 6d6f6f76 "," mov "), Array (" 3026B2758E66CF11 "," ASF "), ARRA    Y ("4d546864", "mid")); The public static function Getfiletype ($filename) {if (!self:: $CheckClass)-Self:: $CheckClass =new-Self ($filena        ME);        $class =self:: $CheckClass;    Return $class->_getfiletype ($filename); }} $filename = "22.jpg"; Echo $filename, "T", Cfiletypecheck::getfiletype ($filename), "rn"; $filename = "11.doc"; echo $ FileName, "T", Cfiletypecheck::getfiletype ($filename), "RN";

Or you can detect this:

$filename = ' 22.jpg '; $extname = Strtolower (substr ($filename, Strrpos ($filename, '. ') + 1); Echo $extname. '
'; $file = @fopen ($filename, ' RB ');        if ($file) {$str = @fread ($file, 0x400);//Read the first 1024 bytes of Echo substr ($str, 0, 4);    @fclose ($file);        } if (substr ($str, 0, 4) = = ' MThd ' && $extname! = ' txt ') {$format = ' mid ';        } elseif (substr ($str, 0, 4) = = ' RIFF ' && $extname = = ' wav ') {$format = ' wav ';        } elseif (substr ($str, 0, 3) = = "/xff/xd8/xff") {$format = ' jpg ';        } elseif (substr ($str, 0, 4) = = ' GIF8 ' && $extname! = ' txt ') {$format = ' gif ';        } elseif (substr ($str, 0, 8) = = "/x89/x50/x4e/x47/x0d/x0a/x1a/x0a") {$format = ' png ';        } elseif (substr ($str, 0, 2) = = ' BM ' && $extname! = ' txt ') {$format = ' bmp ';            } ElseIf ((substr ($str, 0, 3) = = ' CWS ' | | substr ($STR, 0, 3) = = ' FWS ') && $extname! = ' txt ') {        $format = ' swf ';     }   ElseIf (substr ($str, 0, 4) = = "/xd0/xcf/x11/xe0") {//d0cf11e = = Docfile = Microsoft Office Document            if (substr ($str, 0x200,4) = = "/xec/xa5/xc1/x00" | | $extname = = ' Doc ') {$format = ' doc '; } elseif (substr ($str, 0x200,2) = = "/x09/x08" | | $extname = = ' xls ') {$format            = ' xls ';            } elseif (substr ($str, 0x200,4) = = "/xfd/xff/xff/xff" | | $extname = = ' ppt ') {$format = ' ppt ';        }} elseif (substr ($str, 0, 4) = = "pk/x03/x04") {$format = ' zip ';        } elseif (substr ($str, 0, 4) = = ' rar! ' && $extname! = ' txt ') {$format = ' Rar ';        } elseif (substr ($str, 0, 4) = = "/x25pdf") {$format = ' pdf ';        } elseif (substr ($str, 0, 3) = = "/x30/x82/x0a") {$format = ' cert '; } elseif (substr ($str, 0, 4) = = ' ITSF ' && $extname! = ' txt ') {$FORmat = ' chm ';        } elseif (substr ($str, 0, 4) = = "/x2ermf") {$format = ' rm ';        } elseif ($extname = = ' sql ') {$format = ' sql ';        } elseif ($extname = = ' txt ') {$format = ' txt '; }echo $format;

http://www.bkjia.com/PHPjc/752375.html www.bkjia.com true http://www.bkjia.com/PHPjc/752375.html techarticle file signatures are usually in the header of the file, and if you view the file in hexadecimal, you can see some signature information for the file. If you are using Uestudio to view the zip grid in 16 binary mode ...

