通过文件头准确识别PHP上传的文件类型是怎样的

这篇文章将为大家详细讲解有关通过文件头准确识别PHP上传的文件类型有哪些，文章内容质量较高，因此小编分享给大家做个参考，希望大家阅读完这篇文章后对相关知识有一定的了解。

';  $file = @fopen($filename, 'rb');  if ($file)  {    $str = @fread($file, 0x400); // 读取前 1024 个字节    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;

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