PHP根据文件头检测文件类型

http://www.nowamagic.net/librarys/veda/detail/836

文件签名一般都在文件的头部，如果你用十六进制方式查看文件，你就可以看到文件的一些签名信息。如用uestudio以十六进制方式查看zip格式的文件，其文件内容头部有50 4B 03 04这样的十六进制信息。同理jpg文件状况有FF D8 FF E0 xx xx 4A 46这样的十六进制信息，其实这此十六进制都是表示一些特殊字条。

php怎么样验证文件类型？先来看一个简单的方法：

01	function checkFileType($fileName){

02	$file = fopen($fileName, "rb");

03	$bin = fread($file, 2); //只读2字节

04	fclose($file);

05	// C为无符号整数，网上搜到的都是c，为有符号整数，这样会产生负数判断不正常

06	$strInfo  = @unpack("C2chars", $bin);

07	$typeCode = intval($strInfo["chars1"].$strInfo["chars2"]);

08	$fileType = "";

09

10	switch( $typeCode )

11

{

12	case "255216":

13	return $typeCode. " : " ."jpg";

14

break;

15	case "7173":

16	return $typeCode. " : " ."gif";

17

break;

18	case "13780":

19	return $typeCode. " : " ."png";

20

break;

21	case "6677":

22	return $typeCode. " : " ."bmp";

23

break;

24	case "7790":

25	return $typeCode. " : " ."exe";

26

break;

27	case "7784":

28	return $typeCode. " : " ."midi";

29

break;

30	case "8297":

31	return $typeCode. " : " ."rar";

32

break;

33

default:

34	return $typeCode. " : " ."Unknown";

35

break;

36

}

37	//return $typeCode;

38

}

39

40	$file_name = "11.doc";

41	echo checkFileType($file_name);

下来提供一个类的实现：

01	/*通过文件名，获得文件类型*

02	*@author chengmo QQ:8292669*

03	*@copyright <a href="http://www.cnblogs.com/chengmo">http://www.cnblogs.com/chengmo</a> 2010-10-17

04	*@version 0.1

05	*$filename="d:/1.png";echo cFileTypeCheck::getFileType($filename); 打印：png

06

*/

07	class cFileTypeCheck

08

{

09	private static $_TypeList=array();

10	private static $CheckClass=null;

11	private function __construct($filename)

12

{

13	self::$_TypeList=$this->getTypeList();

14

}

15

16

/**

17	*处理文件类型映射关系表*

18

*

19	* @param string $filename 文件类型

20	* @return string 文件类型，没有找到返回：other

21

*/

22	private function _getFileType($filename)

23

{

24	$filetype="other";

25	if(!file_exists($filename)) throw new Exception("no found file!");

26	$file = @fopen($filename,"rb");

27	if(!$file) throw new Exception("file refuse!");

28	$bin = fread($file, 15); //只读15字节 各个不同文件类型，头信息不一样。

29	fclose($file);

30

31	$typelist=self::$_TypeList;

32	foreach ($typelist as $v)

33

{

34	$blen=strlen(pack("H*",$v[0])); //得到文件头标记字节数

35	$tbin=substr($bin,0,intval($blen)); ///需要比较文件头长度

36

37	if(strtolower($v[0])==strtolower(array_shift(unpack("H*",$tbin))))

38

{

39	return $v[1];

40

}

41

}

42	return $filetype;

43

}

44

45

/**

46	*得到文件头与文件类型映射表*

47

*

48	* @return array array(array("key",value)...)

49

*/

50	public function getTypeList()

51

{

52	return array(array("FFD8FFE1","jpg"),

53	array("89504E47","png"),

54	array("47494638","gif"),

55	array("49492A00","tif"),

56	array("424D","bmp"),

57	array("41433130","dwg"),

58	array("38425053","psd"),

59	array("7B5C727466","rtf"),

60	array("3C3F786D6C","xml"),

61	array("68746D6C3E","html"),

62	array("44656C69766572792D646174","eml"),

63	array("CFAD12FEC5FD746F","dbx"),

64	array("2142444E","pst"),

65	array("D0CF11E0","xls/doc"),

66	array("5374616E64617264204A","mdb"),

67	array("FF575043","wpd"),

68	array("252150532D41646F6265","eps/ps"),

69	array("255044462D312E","pdf"),

70	array("E3828596","pwl"),

71	array("504B0304","zip"),

72	array("52617221","rar"),

73	array("57415645","wav"),

74	array("41564920","avi"),

75	array("2E7261FD","ram"),

76	array("2E524D46","rm"),

77	array("000001BA","mpg"),

78	array("000001B3","mpg"),

79	array("6D6F6F76","mov"),

80	array("3026B2758E66CF11","asf"),

81	array("4D546864","mid"));

82

}

83

84

85	public static function getFileType($filename)

86

{

87	if(!self::$CheckClass) self::$CheckClass=new self($filename);

88	$class=self::$CheckClass;

89	return $class->_getFileType($filename);

90

}

91

92

}

93

94	$filename="22.jpg";

95	echo $filename,"t",cFileTypeCheck::getFileType($filename),"rn";

96	$filename="11.doc";

97	echo $filename,"t",cFileTypeCheck::getFileType($filename),"rn";

或者可以这么检测：

01	$filename = "22.jpg";

02

03	$extname = strtolower(substr($filename, strrpos($filename, ".") + 1));

04	echo $extname."<br />";

05	$file = @fopen($filename, "rb");

06	if ($file)

07

{

08	$str = @fread($file, 0x400); // 读取前 1024 个字节

09	echo substr($str, 0, 4);

10	@fclose($file);

11

}

12	if (substr($str, 0, 4) == "MThd" && $extname != "txt")

13

{

14	$format = "mid";

15

}

16	elseif (substr($str, 0, 4) == "RIFF" && $extname == "wav")

17

{

18	$format = "wav";

19

}

20	elseif (substr($str ,0, 3) == "/xFF/xD8/xFF")

21

{

22	$format = "jpg";

23

}

24	elseif (substr($str ,0, 4) == "GIF8" && $extname != "txt")

25

{

26	$format = "gif";

27

}

28	elseif (substr($str ,0, 8 ) == "/x89/x50/x4E/x47/x0D/x0A/x1A/x0A")

29

{

30	$format = "png";

31

}

32	elseif (substr($str ,0, 2) == "BM" && $extname != "txt")

33

{

34	$format = "bmp";

35

}

36	elseif ((substr($str ,0, 3) == "CWS" || substr($str ,0, 3) == "FWS") && $extname != "txt")

37

{

38	$format = "swf";

39

}

40	elseif (substr($str ,0, 4) == "/xD0/xCF/x11/xE0")

41	{   // D0CF11E == DOCFILE == Microsoft Office Document

42	if (substr($str,0x200,4) == "/xEC/xA5/xC1/x00" || $extname == "doc")

43

{

44	$format = "doc";

45

}

46	elseif (substr($str,0x200,2) == "/x09/x08" || $extname == "xls")

47

{

48	$format = "xls";

49	} elseif (substr($str,0x200,4) == "/xFD/xFF/xFF/xFF" || $extname == "ppt")

50

{

51	$format = "ppt";

52

}

53	} elseif (substr($str ,0, 4) == "PK/x03/x04")

54

{

55	$format = "zip";

56	} elseif (substr($str ,0, 4) == "Rar!" && $extname != "txt")

57

{

58	$format = "rar";

59	} elseif (substr($str ,0, 4) == "/x25PDF")

60

{

61	$format = "pdf";

62	} elseif (substr($str ,0, 3) == "/x30/x82/x0A")

63

{

64	$format = "cert";

65	} elseif (substr($str ,0, 4) == "ITSF" && $extname != "txt")

66

{

67	$format = "chm";

68	} elseif (substr($str ,0, 4) == "/x2ERMF")

69

{

70	$format = "rm";

71	} elseif ($extname == "sql")

72

{

73	$format = "sql";

74	} elseif ($extname == "txt")

75

{

76	$format = "txt";

77

}

78

79	echo $format;