Python通过文件头来判断文件的真实类型

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# 文章：Python通过文件头来判断文件类型
# 作者：http://aminby.net
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import struct

# 支持文件类型
# 用16进制字符串的目的是可以知道文件头是多少字节
# 各种文件头的长度不一样，少半2字符，长则8字符
def typeList():
return {
"FFD8FF": "jpg",
"89504E47": "png",
"47494638": "gif",
"49492A00": "tif",
"424D": "bmp",
"41433130": "dwg",
"38425053": "psd",
"7B5C727466": "rtf",
"3C3F786D6C": "xml",
"68746D6C3E": "html",
"44656C69766572792D646174653A": "eml",
"CFAD12FEC5FD746F": "dbx",
"2142444E": "pst",
"D0CF11E0": "xls.or.doc",
"5374616E64617264204A": "mdb",
"FF575043": "wpd",
"252150532D41646F6265": "eps.or.ps",
"255044462D312E": "pdf",
"AC9EBD8F": "qdf",
"E3828596": "pwl",
"504B0304": "zip",
"52617221": "rar",
"57415645": "wav",
"41564920": "avi",
"2E7261FD": "ram",
"2E524D46": "rm",
"000001BA": "mpg",
"000001B3": "mpg",
"6D6F6F76": "mov",
"3026B2758E66CF11": "asf",
"4D546864": "mid",
"4D5A": "pe"
}

# 字节码转16进制字符串
def bytes2hex(bytes):
num = len(bytes)
hexstr = u""
for i in range(num):
t = u"%x" % bytes[i]
if len(t) % 2:
hexstr += u"0"
hexstr += t
return hexstr.upper()

# 获取文件类型
def filetype(filename):
binfile = open(filename, 'rb') # 必需二制字读取
tl = typeList()
ftype = 'unknown'
for hcode in tl.keys():
numOfBytes = len(hcode) / 2 # 需要读多少字节
binfile.seek(0) # 每次读取都要回到文件头，不然会一直往后读取
hbytes = struct.unpack_from("B"*numOfBytes, binfile.read(numOfBytes)) # 一个 "B"表示一个字节
f_hcode = bytes2hex(hbytes)
if f_hcode == hcode:
ftype = tl[hcode]
break
binfile.close()
return ftype

if __name__ == '__main__':
print filetype("C:\\Users\\1\\Desktop\\sogou_explorer_4.2_0121.4092636479_BDdl.exe")