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;
}

@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.