converting mime types to extension in php

mime2ext.php

function mime2ext($mime){
  $all_mimes = '{"png":["image\/png","image\/x-png"],"bmp":["image\/bmp","image\/x-bmp","image\/x-bitmap","image\/x-xbitmap","image\/x-win-bitmap","image\/x-windows-bmp","image\/ms-bmp","image\/x-ms-bmp","application\/bmp","application\/x-bmp","application\/x-win-bitmap"],"gif":["image\/gif"],"jpeg":["image\/jpeg","image\/pjpeg"],"xspf":["application\/xspf+xml"],"vlc":["application\/videolan"],"wmv":["video\/x-ms-wmv","video\/x-ms-asf"],"au":["audio\/x-au"],"ac3":["audio\/ac3"],"flac":["audio\/x-flac"],"ogg":["audio\/ogg","video\/ogg","application\/ogg"],"kmz":["application\/vnd.google-earth.kmz"],"kml":["application\/vnd.google-earth.kml+xml"],"rtx":["text\/richtext"],"rtf":["text\/rtf"],"jar":["application\/java-archive","application\/x-java-application","application\/x-jar"],"zip":["application\/x-zip","application\/zip","application\/x-zip-compressed","application\/s-compressed","multipart\/x-zip"],"7zip":["application\/x-compressed"],"xml":["application\/xml","text\/xml"],"svg":["image\/svg+xml"],"3g2":["video\/3gpp2"],"3gp":["video\/3gp","video\/3gpp"],"mp4":["video\/mp4"],"m4a":["audio\/x-m4a"],"f4v":["video\/x-f4v"],"flv":["video\/x-flv"],"webm":["video\/webm"],"aac":["audio\/x-acc"],"m4u":["application\/vnd.mpegurl"],"pdf":["application\/pdf","application\/octet-stream"],"pptx":["application\/vnd.openxmlformats-officedocument.presentationml.presentation"],"ppt":["application\/powerpoint","application\/vnd.ms-powerpoint","application\/vnd.ms-office","application\/msword"],"docx":["application\/vnd.openxmlformats-officedocument.wordprocessingml.document"],"xlsx":["application\/vnd.openxmlformats-officedocument.spreadsheetml.sheet","application\/vnd.ms-excel"],"xl":["application\/excel"],"xls":["application\/msexcel","application\/x-msexcel","application\/x-ms-excel","application\/x-excel","application\/x-dos_ms_excel","application\/xls","application\/x-xls"],"xsl":["text\/xsl"],"mpeg":["video\/mpeg"],"mov":["video\/quicktime"],"avi":["video\/x-msvideo","video\/msvideo","video\/avi","application\/x-troff-msvideo"],"movie":["video\/x-sgi-movie"],"log":["text\/x-log"],"txt":["text\/plain"],"css":["text\/css"],"html":["text\/html"],"wav":["audio\/x-wav","audio\/wave","audio\/wav"],"xhtml":["application\/xhtml+xml"],"tar":["application\/x-tar"],"tgz":["application\/x-gzip-compressed"],"psd":["application\/x-photoshop","image\/vnd.adobe.photoshop"],"exe":["application\/x-msdownload"],"js":["application\/x-javascript"],"mp3":["audio\/mpeg","audio\/mpg","audio\/mpeg3","audio\/mp3"],"rar":["application\/x-rar","application\/rar","application\/x-rar-compressed"],"gzip":["application\/x-gzip"],"hqx":["application\/mac-binhex40","application\/mac-binhex","application\/x-binhex40","application\/x-mac-binhex40"],"cpt":["application\/mac-compactpro"],"bin":["application\/macbinary","application\/mac-binary","application\/x-binary","application\/x-macbinary"],"oda":["application\/oda"],"ai":["application\/postscript"],"smil":["application\/smil"],"mif":["application\/vnd.mif"],"wbxml":["application\/wbxml"],"wmlc":["application\/wmlc"],"dcr":["application\/x-director"],"dvi":["application\/x-dvi"],"gtar":["application\/x-gtar"],"php":["application\/x-httpd-php","application\/php","application\/x-php","text\/php","text\/x-php","application\/x-httpd-php-source"],"swf":["application\/x-shockwave-flash"],"sit":["application\/x-stuffit"],"z":["application\/x-compress"],"mid":["audio\/midi"],"aif":["audio\/x-aiff","audio\/aiff"],"ram":["audio\/x-pn-realaudio"],"rpm":["audio\/x-pn-realaudio-plugin"],"ra":["audio\/x-realaudio"],"rv":["video\/vnd.rn-realvideo"],"jp2":["image\/jp2","video\/mj2","image\/jpx","image\/jpm"],"tiff":["image\/tiff"],"eml":["message\/rfc822"],"pem":["application\/x-x509-user-cert","application\/x-pem-file"],"p10":["application\/x-pkcs10","application\/pkcs10"],"p12":["application\/x-pkcs12"],"p7a":["application\/x-pkcs7-signature"],"p7c":["application\/pkcs7-mime","application\/x-pkcs7-mime"],"p7r":["application\/x-pkcs7-certreqresp"],"p7s":["application\/pkcs7-signature"],"crt":["application\/x-x509-ca-cert","application\/pkix-cert"],"crl":["application\/pkix-crl","application\/pkcs-crl"],"pgp":["application\/pgp"],"gpg":["application\/gpg-keys"],"rsa":["application\/x-pkcs7"],"ics":["text\/calendar"],"zsh":["text\/x-scriptzsh"],"cdr":["application\/cdr","application\/coreldraw","application\/x-cdr","application\/x-coreldraw","image\/cdr","image\/x-cdr","zz-application\/zz-winassoc-cdr"],"wma":["audio\/x-ms-wma"],"vcf":["text\/x-vcard"],"srt":["text\/srt"],"vtt":["text\/vtt"],"ico":["image\/x-icon","image\/x-ico","image\/vnd.microsoft.icon"],"csv":["text\/x-comma-separated-values","text\/comma-separated-values","application\/vnd.msexcel"],"json":["application\/json","text\/json"]}';
  $all_mimes = json_decode($all_mimes,true);
  foreach ($all_mimes as $key => $value) {
    if(array_search($mime,$value) !== false) return $key;
  }
  return false;
}

Should 'application/octet-stream' not map to false/null? According to the RFC, it can be any arbitrary binary data. I'm not sure how this should be handled, but maybe we can just exclude it, or comment it out such that it's obvious that it was intentional to remove it. I'm not sure why it currently points to the pdf extension.

@billynoah ,

I hate to revive an old post, but you definitely need:
'image/jpg' => 'jpg',

Yes, I'm aware it isn't an official MIME type, but I have encountered it in the wild-- specifically from incoming mail from MailChimp's web hook-- so I had to add it into my code. I've seen several other websites which now list it as a valid mime type.