Powerful php checking file types

A powerful file type detection function that can determine the type of the file you upload. You cannot install the file in the past. For more information, see.

The Code is as follows:

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** * * * @ Access public * @ Param string filename file name * @ Param string limit_ext_types: the file type allowed. | used | The surrounded type is: | gif | txt | * @ Return string */<Span id = "more-472" type = "codeph" text = "/codeph"> </span type = "codeph" text = "/codeph"> Function check_file_type ($ filename, $ limit_ext_types = ''){ $ Extname = strtolower (substr ($ filename, strrpos ($ filename, '.') + 1 )); If ($ limit_ext_types && Stristr ($ limit_ext_types, '|'. $ extname. '|') = false ){ Return ''; }   $ Str = $ format = '';   $ File = @ fopen ($ filename, 'rb '); If ($ file ){ $ Str = @ fread ($ file, 0x400); // read the first 1024 bytes @ Fclose ($ file ); } Else { $ Format = $ extname; }   If ($ format = ''& strlen ($ str)> = 2 ){ 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) = "xFFxD8xFF "){ $ Format = 'jpg '; } Elseif (substr ($ str, 0, 4) = 'gif 8' & $ extname! = 'Txt '){ $ Format = 'gif '; } Elseif (substr ($ str, 0, 8) = "x89x50x4Ex47x0Dx0Ax1Ax0A "){ $ Format = 'png '; } Elseif (substr ($ str, 0, 2) = 'bm '& $ extname! = 'Txt '){ $ Format = 'bmp '; } Elseif (substr ($ str, 0, 3) = 'done' | substr ($ str, 0, 3) = 'fws ') & $ Extname! = 'Txt '){ $ Format = 'swf '; } Elseif (substr ($ str, 0, 4) = "xD0xCFx11xE0") {// D0CF11E = DOCFILE = Microsoft Office Document If (substr ($ str, 0x200,4) = "xECxA5xC1x00" | $ Extname = 'Doc '){ $ Format = 'Doc '; } Elseif (substr ($ str, 0 x, 2) = "x09x08" | $ extname = 'xls '){ $ Format = 'xls '; } Elseif (substr ($ str, 0x200,4) = "xFDxFFxFFxFF" | $ Extname = 'ppt '){ $ Format = 'ppt '; } } Elseif (substr ($ str, 0, 4) = "PKx03x04 "){ $ 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) = "x30x82x0A "){ $ 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 '; } }   If ($ limit_ext_types && Stristr ($ limit_ext_types, '|'. $ format. '|') = false ){ $ Format = ''; }   Return $ format; }