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强大的文件类型检测函数php代码

时间：2021-07-01 10:21:17 帮助过：12人阅读

  2. /**
  3. * @access public
  4. * @param string filename 文件名
  5. * @param string limit_ext_types 允许的文件类型，用|包围的类型如：|gif|txt|
  6. * @return string
  7. * by http://bbs.it-home.org
  8. */
  9. function check_file_type($filename, $limit_ext_types = ''){
  10. $extname = strtolower(substr($filename, strrpos($filename, '.') + 1));
  11. if ($limit_ext_types &&
  12. stristr($limit_ext_types, '|' . $extname . '|') === false){
  13. return '';
  14. }
  16. $str = $format = '';
  18. $file = @fopen($filename, 'rb');
  19. if ($file){
  20. $str = @fread($file, 0x400); // 读取前 1024 个字节
  21. @fclose($file);
  22. }
  23. else{
  24. $format=$extname;
  25. }
  27. if ($format == '' && strlen($str) >= 2 ){
  28. if (substr($str, 0, 4) == 'MThd' && $extname != 'txt'){
  29. $format = 'mid';
  30. }
  31. elseif (substr($str, 0, 4) == 'RIFF' && $extname == 'wav'){
  32. $format = 'wav';
  33. }
  34. elseif (substr($str ,0, 3) == "xFFxD8xFF"){
  35. $format = 'jpg';
  36. }
  37. elseif (substr($str ,0, 4) == 'GIF8' && $extname != 'txt'){
  38. $format = 'gif';
  39. }
  40. elseif (substr($str ,0, 8) == "x89x50x4Ex47x0Dx0Ax1Ax0A"){
  41. $format = 'png';
  42. }
  43. elseif (substr($str ,0, 2) == 'BM' && $extname != 'txt'){
  44. $format = 'bmp';
  45. }
  46. elseif ((substr($str ,0, 3) == 'CWS' || substr($str ,0, 3) == 'FWS')
  47. && $extname != 'txt'){
  48. $format = 'swf';
  49. }
  50. elseif (substr($str ,0, 4) == "xD0xCFx11xE0"){ // D0CF11E == DOCFILE == Microsoft Office Document
  51. if (substr($str,0x200,4) == "xECxA5xC1x00"
  52. || $extname == 'doc'){
  53. $format = 'doc';
  54. }
  55. elseif (substr($str,0x200,2) == "x09x08" || $extname == 'xls'){
  56. $format = 'xls';
  57. }
  58. elseif (substr($str,0x200,4) == "xFDxFFxFFxFF"
  59. || $extname == 'ppt'){
  60. $format = 'ppt';
  61. }
  62. }
  63. elseif (substr($str ,0, 4) == "PKx03x04"){
  64. $format = 'zip';
  65. }
  66. elseif (substr($str ,0, 4) == 'Rar!' && $extname != 'txt'){
  67. $format = 'rar';
  68. }
  69. elseif (substr($str ,0, 4) == "x25PDF"){
  70. $format = 'pdf';
  71. }
  72. elseif (substr($str ,0, 3) == "x30x82x0A"){
  73. $format = 'cert';
  74. }
  75. elseif (substr($str ,0, 4) == 'ITSF' && $extname != 'txt'){
  76. $format = 'chm';
  77. }
  78. elseif (substr($str ,0, 4) == "x2ERMF"){
  79. $format = 'rm';
  80. }
  81. elseif ($extname == 'sql'){
  82. $format = 'sql';
  83. }
  84. elseif ($extname == 'txt'){
  85. $format = 'txt';
  86. }
  87. }
  89. if ($limit_ext_types &&
  90. stristr($limit_ext_types, '|' . $format . '|') === false){
  91. $format = '';
  92. }
  94. return $format;
  95. }

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