MimeUtils.java

  1/*
  2 * Copyright (C) 2010 The Android Open Source Project
  3 *
  4 * Licensed under the Apache License, Version 2.0 (the "License");
  5 * you may not use this file except in compliance with the License.
  6 * You may obtain a copy of the License at
  7 *
  8 *      http://www.apache.org/licenses/LICENSE-2.0
  9 *
 10 * Unless required by applicable law or agreed to in writing, software
 11 * distributed under the License is distributed on an "AS IS" BASIS,
 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 13 * See the License for the specific language governing permissions and
 14 * limitations under the License.
 15 */
 16package eu.siacs.conversations.utils;
 17
 18import android.content.Context;
 19import android.database.Cursor;
 20import android.net.Uri;
 21import android.provider.OpenableColumns;
 22import android.util.Log;
 23import com.google.common.base.Strings;
 24import com.google.common.collect.ImmutableList;
 25import eu.siacs.conversations.Config;
 26import eu.siacs.conversations.entities.Transferable;
 27import eu.siacs.conversations.worker.ExportBackupWorker;
 28import java.io.File;
 29import java.io.FileInputStream;
 30import java.io.IOException;
 31import java.io.InputStream;
 32import java.util.Arrays;
 33import java.util.Collection;
 34import java.util.HashMap;
 35import java.util.List;
 36import java.util.Map;
 37import java.util.Properties;
 38
 39/**
 40 * Utilities for dealing with MIME types. Used to implement java.net.URLConnection and
 41 * android.webkit.MimeTypeMap.
 42 */
 43public final class MimeUtils {
 44
 45    public static final List<String> AMBIGUOUS_CONTAINER_FORMATS =
 46            ImmutableList.of(
 47                    "application/ogg",
 48                    "video/3gpp", // .3gp files can contain audio, video or both
 49                    "video/3gpp2");
 50
 51    public static final List<String> WORD_DOCUMENT_MIMES =
 52            Arrays.asList(
 53                    "application/vnd.oasis.opendocument.text",
 54                    "application/msword",
 55                    "application/vnd.openxmlformats-officedocument.wordprocessingml.document");
 56
 57    private static final Map<String, String> mimeTypeToExtensionMap = new HashMap<>();
 58    private static final Map<String, String> extensionToMimeTypeMap = new HashMap<>();
 59
 60    static {
 61        // The following table is based on /etc/mime.types data minus
 62        // chemical/* MIME types and MIME types that don't map to any
 63        // file extensions. We also exclude top-level domain names to
 64        // deal with cases like:
 65        //
 66        // mail.google.com/a/google.com
 67        //
 68        // and "active" MIME types (due to potential security issues).
 69        // Note that this list is _not_ in alphabetical order and must not be sorted.
 70        // The "most popular" extension must come first, so that it's the one returned
 71        // by guessExtensionFromMimeType.
 72        add("application/andrew-inset", "ez");
 73        add("application/dsptype", "tsp");
 74        add("application/json", "json");
 75        add("application/epub+zip", "epub");
 76        add("application/gpx+xml", "gpx");
 77        add("application/hta", "hta");
 78        add("application/mac-binhex40", "hqx");
 79        add("application/mathematica", "nb");
 80        add("application/msaccess", "mdb");
 81        add("application/oda", "oda");
 82        add("application/ogg", "ogg");
 83        add("application/pdf", "pdf");
 84        add("application/pgp-keys", "key");
 85        add("application/pgp-signature", "pgp");
 86        add("application/pics-rules", "prf");
 87        add("application/pkix-cert", "cer");
 88        add("application/rar", "rar");
 89        add("application/rdf+xml", "rdf");
 90        add("application/rss+xml", "rss");
 91        add("application/zip", "zip");
 92        add("application/vnd.amazon.mobi8-ebook", "azw3");
 93        add("application/vnd.amazon.mobi8-ebook", "azw");
 94        add("application/vnd.amazon.mobi8-ebook", "kfx");
 95        add("application/vnd.android.package-archive", "apk");
 96        add("application/vnd.cinderella", "cdy");
 97        add(ExportBackupWorker.MIME_TYPE, "ceb");
 98        add("application/vnd.ms-pki.stl", "stl");
 99        add("application/vnd.oasis.opendocument.database", "odb");
100        add("application/vnd.oasis.opendocument.formula", "odf");
101        add("application/vnd.oasis.opendocument.graphics", "odg");
102        add("application/vnd.oasis.opendocument.graphics-template", "otg");
103        add("application/vnd.oasis.opendocument.image", "odi");
104        add("application/vnd.oasis.opendocument.spreadsheet", "ods");
105        add("application/vnd.oasis.opendocument.spreadsheet-template", "ots");
106        add("application/vnd.oasis.opendocument.text", "odt");
107        add("application/vnd.oasis.opendocument.text-master", "odm");
108        add("application/vnd.oasis.opendocument.text-template", "ott");
109        add("application/vnd.oasis.opendocument.text-web", "oth");
110        add("application/vnd.oasis.opendocument.presentation", "odp");
111        add("application/vnd.google-earth.kml+xml", "kml");
112        add("application/vnd.google-earth.kmz", "kmz");
113        add("application/msword", "doc");
114        add("application/msword", "dot");
115        add("application/vnd.openxmlformats-officedocument.wordprocessingml.document", "docx");
116        add("application/vnd.openxmlformats-officedocument.wordprocessingml.template", "dotx");
117        add("application/vnd.ms-excel", "xls");
118        add("application/vnd.ms-excel", "xlt");
119        add("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "xlsx");
120        add("application/vnd.openxmlformats-officedocument.spreadsheetml.template", "xltx");
121        add("application/vnd.ms-powerpoint", "ppt");
122        add("application/vnd.ms-powerpoint", "pot");
123        add("application/vnd.ms-powerpoint", "pps");
124        add("application/vnd.openxmlformats-officedocument.presentationml.presentation", "pptx");
125        add("application/vnd.openxmlformats-officedocument.presentationml.template", "potx");
126        add("application/vnd.openxmlformats-officedocument.presentationml.slideshow", "ppsx");
127        add("application/vnd.rim.cod", "cod");
128        add("application/vnd.smaf", "mmf");
129        add("application/vnd.stardivision.calc", "sdc");
130        add("application/vnd.stardivision.draw", "sda");
131        add("application/vnd.stardivision.impress", "sdd");
132        add("application/vnd.stardivision.impress", "sdp");
133        add("application/vnd.stardivision.math", "smf");
134        add("application/vnd.stardivision.writer", "sdw");
135        add("application/vnd.stardivision.writer", "vor");
136        add("application/vnd.stardivision.writer-global", "sgl");
137        add("application/vnd.sun.xml.calc", "sxc");
138        add("application/vnd.sun.xml.calc.template", "stc");
139        add("application/vnd.sun.xml.draw", "sxd");
140        add("application/vnd.sun.xml.draw.template", "std");
141        add("application/vnd.sun.xml.impress", "sxi");
142        add("application/vnd.sun.xml.impress.template", "sti");
143        add("application/vnd.sun.xml.math", "sxm");
144        add("application/vnd.sun.xml.writer", "sxw");
145        add("application/vnd.sun.xml.writer.global", "sxg");
146        add("application/vnd.sun.xml.writer.template", "stw");
147        add("application/vnd.visio", "vsd");
148        add("application/x-7z-compressed", "7z");
149        add("application/x-abiword", "abw");
150        add("application/x-apple-diskimage", "dmg");
151        add("application/x-bcpio", "bcpio");
152        add("application/x-bittorrent", "torrent");
153        add("application/x-cdf", "cdf");
154        add("application/x-cdlink", "vcd");
155        add("application/x-chess-pgn", "pgn");
156        add("application/x-cpio", "cpio");
157        add("application/x-debian-package", "deb");
158        add("application/x-debian-package", "udeb");
159        add("application/x-director", "dcr");
160        add("application/x-director", "dir");
161        add("application/x-director", "dxr");
162        add("application/x-dms", "dms");
163        add("application/x-doom", "wad");
164        add("application/x-dvi", "dvi");
165        add("application/x-font", "pfa");
166        add("application/x-font", "pfb");
167        add("application/x-font", "gsf");
168        add("application/x-font", "pcf");
169        add("application/x-font", "pcf.Z");
170        add("application/x-freemind", "mm");
171        // application/futuresplash isn't IANA, so application/x-futuresplash should come first.
172        add("application/x-futuresplash", "spl");
173        add("application/futuresplash", "spl");
174        add("application/x-gnumeric", "gnumeric");
175        add("application/x-go-sgf", "sgf");
176        add("application/x-graphing-calculator", "gcf");
177        add("application/x-gtar", "tgz");
178        add("application/x-gtar", "gtar");
179        add("application/x-gtar", "taz");
180        add("application/x-hdf", "hdf");
181        add("application/x-ica", "ica");
182        add("application/x-internet-signup", "ins");
183        add("application/x-internet-signup", "isp");
184        add("application/x-iphone", "iii");
185        add("application/x-iso9660-image", "iso");
186        add("application/x-jmol", "jmz");
187        add("application/x-kchart", "chrt");
188        add("application/x-killustrator", "kil");
189        add("application/x-koan", "skp");
190        add("application/x-koan", "skd");
191        add("application/x-koan", "skt");
192        add("application/x-koan", "skm");
193        add("application/x-kpresenter", "kpr");
194        add("application/x-kpresenter", "kpt");
195        add("application/x-kspread", "ksp");
196        add("application/x-kword", "kwd");
197        add("application/x-kword", "kwt");
198        add("application/x-latex", "latex");
199        add("application/x-lha", "lha");
200        add("application/x-lzh", "lzh");
201        add("application/x-lzx", "lzx");
202        add("application/x-maker", "frm");
203        add("application/x-maker", "maker");
204        add("application/x-maker", "frame");
205        add("application/x-maker", "fb");
206        add("application/x-maker", "book");
207        add("application/x-maker", "fbdoc");
208        add("application/x-mif", "mif");
209        add("application/x-mobipocket-ebook", "mobi");
210        add("application/x-ms-wmd", "wmd");
211        add("application/x-ms-wmz", "wmz");
212        add("application/x-msi", "msi");
213        add("application/x-ns-proxy-autoconfig", "pac");
214        add("application/x-nwc", "nwc");
215        add("application/x-object", "o");
216        add("application/x-oz-application", "oza");
217        add("application/x-pem-file", "pem");
218        add("application/x-pkcs12", "p12");
219        add("application/x-pkcs12", "pfx");
220        add("application/x-pkcs7-certreqresp", "p7r");
221        add("application/x-pkcs7-crl", "crl");
222        add("application/x-quicktimeplayer", "qtl");
223        add("application/x-shar", "shar");
224        add("application/x-shockwave-flash", "swf");
225        add("application/x-stuffit", "sit");
226        add("application/x-sv4cpio", "sv4cpio");
227        add("application/x-sv4crc", "sv4crc");
228        add("application/x-tar", "tar");
229        add("application/x-texinfo", "texinfo");
230        add("application/x-texinfo", "texi");
231        add("application/x-troff", "t");
232        add("application/x-troff", "roff");
233        add("application/x-troff-man", "man");
234        add("application/x-ustar", "ustar");
235        add("application/x-wais-source", "src");
236        add("application/x-wingz", "wz");
237        add("application/x-webarchive", "webarchive");
238        add("application/x-webarchive-xml", "webarchivexml");
239        add("application/x-x509-ca-cert", "crt");
240        add("application/x-x509-user-cert", "crt");
241        add("application/x-x509-server-cert", "crt");
242        add("application/x-xcf", "xcf");
243        add("application/x-xfig", "fig");
244        add("application/webxdc+zip", "xdc");
245        add("application/xhtml+xml", "xhtml");
246        add("video/3gpp", "3gpp");
247        add("video/3gpp", "3gp");
248        add("video/3gpp2", "3gpp2");
249        add("video/3gpp2", "3g2");
250        add("audio/3gpp", "3gpp");
251        add("audio/3gpp", "3gp");
252        add("audio/aac", "aac");
253        add("audio/aac-adts", "aac");
254        add("audio/amr", "amr");
255        add("audio/amr-wb", "awb");
256        add("audio/basic", "snd");
257        add("audio/flac", "flac");
258        add("application/x-flac", "flac");
259        add("audio/imelody", "imy");
260        add("audio/midi", "mid");
261        add("audio/midi", "midi");
262        add("audio/midi", "ota");
263        add("audio/midi", "kar");
264        add("audio/midi", "rtttl");
265        add("audio/midi", "xmf");
266        add("audio/mobile-xmf", "mxmf");
267        // add ".mp3" first so it will be the default for guessExtensionFromMimeType
268        add("audio/mpeg", "mp3");
269        add("audio/mpeg", "mpga");
270        add("audio/mpeg", "mpega");
271        add("audio/mpeg", "mp2");
272        add("audio/mp4", "m4a");
273        add("audio/x-m4b", "m4b");
274        add("audio/mpegurl", "m3u");
275        add("audio/ogg", "oga");
276        add("audio/ogg; codecs=opus", "opus"); // opus in ogg container
277        add("audio/opus", "opus"); // audio/opus for containerless opus
278        add("audio/prs.sid", "sid");
279        add("audio/x-aiff", "aif");
280        add("audio/x-aiff", "aiff");
281        add("audio/x-aiff", "aifc");
282        add("audio/x-gsm", "gsm");
283        add("audio/x-matroska", "mka");
284        add("audio/x-mpegurl", "m3u");
285        add("audio/x-ms-wma", "wma");
286        add("audio/x-ms-wax", "wax");
287        add("audio/x-pn-realaudio", "ra");
288        add("audio/x-pn-realaudio", "rm");
289        add("audio/x-pn-realaudio", "ram");
290        add("audio/x-realaudio", "ra");
291        add("audio/x-scpls", "pls");
292        add("audio/x-sd2", "sd2");
293        add("audio/x-wav", "wav");
294        // image/bmp isn't IANA, so image/x-ms-bmp should come first.
295        add("image/x-ms-bmp", "bmp");
296        add("image/bmp", "bmp");
297        add("image/gif", "gif");
298        // image/ico isn't IANA, so image/x-icon should come first.
299        add("image/x-icon", "ico");
300        add("image/ico", "cur");
301        add("image/ico", "ico");
302        add("image/ief", "ief");
303        add("image/heic", "heic");
304        add("image/heif", "heif");
305        add("image/avif", "avif");
306        // add ".jpg" first so it will be the default for guessExtensionFromMimeType
307        add("image/jpeg", "jpg");
308        add("image/jpeg", "jpeg");
309        add("image/jpeg", "jpe");
310        add("image/jpeg", "jfif");
311        add("image/jpeg", "jif");
312        add("image/pcx", "pcx");
313        add("image/png", "png");
314        add("image/svg+xml", "svg");
315        add("image/svg+xml", "svgz");
316        add("image/tiff", "tiff");
317        add("image/tiff", "tif");
318        add("image/vnd.djvu", "djvu");
319        add("image/vnd.djvu", "djv");
320        add("image/vnd.wap.wbmp", "wbmp");
321        add("image/webp", "webp");
322        add("image/x-cmu-raster", "ras");
323        add("image/x-coreldraw", "cdr");
324        add("image/x-coreldrawpattern", "pat");
325        add("image/x-coreldrawtemplate", "cdt");
326        add("image/x-corelphotopaint", "cpt");
327        add("image/x-jg", "art");
328        add("image/x-jng", "jng");
329        add("image/x-photoshop", "psd");
330        add("image/x-portable-anymap", "pnm");
331        add("image/x-portable-bitmap", "pbm");
332        add("image/x-portable-graymap", "pgm");
333        add("image/x-portable-pixmap", "ppm");
334        add("image/x-rgb", "rgb");
335        add("image/x-xbitmap", "xbm");
336        add("image/x-xpixmap", "xpm");
337        add("image/x-xwindowdump", "xwd");
338        add("message/rfc822", "eml");
339        add("message/rfc822", "mime");
340        add("model/iges", "igs");
341        add("model/iges", "iges");
342        add("model/mesh", "msh");
343        add("model/mesh", "mesh");
344        add("model/mesh", "silo");
345        add("text/calendar", "ics");
346        add("text/calendar", "icz");
347        add("text/comma-separated-values", "csv");
348        add("text/css", "css");
349        add("text/html", "htm");
350        add("text/html", "html");
351        add("text/h323", "323");
352        add("text/iuls", "uls");
353        add("text/javascript", "js");
354        add("text/mathml", "mml");
355        // add ".txt" first so it will be the default for guessExtensionFromMimeType
356        add("text/plain", "txt");
357        add("text/plain", "asc");
358        add("text/plain", "text");
359        add("text/plain", "diff");
360        add("text/plain", "po"); // reserve "pot" for vnd.ms-powerpoint
361        add("text/richtext", "rtx");
362        add("text/rtf", "rtf");
363        add("text/text", "phps");
364        add("text/tab-separated-values", "tsv");
365        add("text/xml", "xml");
366        add("text/x-bibtex", "bib");
367        add("text/x-boo", "boo");
368        add("text/x-c++hdr", "hpp");
369        add("text/x-c++hdr", "h++");
370        add("text/x-c++hdr", "hxx");
371        add("text/x-c++hdr", "hh");
372        add("text/x-c++src", "cpp");
373        add("text/x-c++src", "c++");
374        add("text/x-c++src", "cc");
375        add("text/x-c++src", "cxx");
376        add("text/x-chdr", "h");
377        add("text/x-component", "htc");
378        add("text/x-csh", "csh");
379        add("text/x-csrc", "c");
380        add("text/x-dsrc", "d");
381        add("text/x-haskell", "hs");
382        add("text/x-java", "java");
383        add("text/x-literate-haskell", "lhs");
384        add("text/x-moc", "moc");
385        add("text/x-pascal", "p");
386        add("text/x-pascal", "pas");
387        add("text/x-pcs-gcd", "gcd");
388        add("text/x-setext", "etx");
389        add("text/x-tcl", "tcl");
390        add("text/x-tex", "tex");
391        add("text/x-tex", "ltx");
392        add("text/x-tex", "sty");
393        add("text/x-tex", "cls");
394        add("text/x-vcalendar", "vcs");
395        add("text/x-vcard", "vcf");
396        add("video/avi", "avi");
397        add("video/dl", "dl");
398        add("video/dv", "dif");
399        add("video/dv", "dv");
400        add("video/fli", "fli");
401        add("video/m4v", "m4v");
402        add("video/mp2ts", "ts");
403        add("video/ogg", "ogv");
404        add("video/mpeg", "mpeg");
405        add("video/mpeg", "mpg");
406        add("video/mpeg", "mpe");
407        add("video/mp4", "mp4");
408        add("video/mpeg", "VOB");
409        add("video/quicktime", "qt");
410        add("video/quicktime", "mov");
411        add("video/vnd.mpegurl", "mxu");
412        add("video/webm", "webm");
413        add("video/x-la-asf", "lsf");
414        add("video/x-la-asf", "lsx");
415        add("video/x-matroska", "mkv");
416        add("video/x-mng", "mng");
417        add("video/x-ms-asf", "asf");
418        add("video/x-ms-asf", "asx");
419        add("video/x-ms-wm", "wm");
420        add("video/x-ms-wmv", "wmv");
421        add("video/x-ms-wmx", "wmx");
422        add("video/x-ms-wvx", "wvx");
423        add("video/x-sgi-movie", "movie");
424        add("video/x-webex", "wrf");
425        add("x-conference/x-cooltalk", "ice");
426        add("x-epoc/x-sisx-app", "sisx");
427        applyOverrides();
428    }
429
430    // mime types that are more reliant by path
431    private static final Collection<String> PATH_PRECEDENCE_MIME_TYPE =
432            Arrays.asList("audio/x-m4b");
433
434    private static void add(String mimeType, String extension) {
435        // If we have an existing x -> y mapping, we do not want to
436        // override it with another mapping x -> y2.
437        // If a mime type maps to several extensions
438        // the first extension added is considered the most popular
439        // so we do not want to overwrite it later.
440        if (!mimeTypeToExtensionMap.containsKey(mimeType)) {
441            mimeTypeToExtensionMap.put(mimeType, extension);
442        }
443        if (!extensionToMimeTypeMap.containsKey(extension)) {
444            extensionToMimeTypeMap.put(extension, mimeType);
445        }
446    }
447
448    private static InputStream getContentTypesPropertiesStream() {
449        // User override?
450        String userTable = System.getProperty("content.types.user.table");
451        if (userTable != null) {
452            File f = new File(userTable);
453            if (f.exists()) {
454                try {
455                    return new FileInputStream(f);
456                } catch (IOException ignored) {
457                }
458            }
459        }
460        // Standard location?
461        File f =
462                new File(
463                        System.getProperty("java.home"),
464                        "lib" + File.separator + "content-types.properties");
465        if (f.exists()) {
466            try {
467                return new FileInputStream(f);
468            } catch (IOException ignored) {
469            }
470        }
471        return null;
472    }
473
474    /**
475     * This isn't what the RI does. The RI doesn't have hard-coded defaults, so supplying your own
476     * "content.types.user.table" means you don't get any of the built-ins, and the built-ins come
477     * from "$JAVA_HOME/lib/content-types.properties".
478     */
479    private static void applyOverrides() {
480        // Get the appropriate InputStream to read overrides from, if any.
481        InputStream stream = getContentTypesPropertiesStream();
482        if (stream == null) {
483            return;
484        }
485        try {
486            try {
487                // Read the properties file...
488                Properties overrides = new Properties();
489                overrides.load(stream);
490                // And translate its mapping to ours...
491                for (Map.Entry<Object, Object> entry : overrides.entrySet()) {
492                    String extension = (String) entry.getKey();
493                    String mimeType = (String) entry.getValue();
494                    add(mimeType, extension);
495                }
496            } finally {
497                stream.close();
498            }
499        } catch (IOException ignored) {
500        }
501    }
502
503    private MimeUtils() {}
504
505    /**
506     * Returns true if the given MIME type has an entry in the map.
507     *
508     * @param mimeType A MIME type (i.e. text/plain)
509     * @return True iff there is a mimeType entry in the map.
510     */
511    public static boolean hasMimeType(String mimeType) {
512        if (mimeType == null || mimeType.isEmpty()) {
513            return false;
514        }
515        return mimeTypeToExtensionMap.containsKey(mimeType);
516    }
517
518    /**
519     * Returns the MIME type for the given extension.
520     *
521     * @param extension A file extension without the leading '.'
522     * @return The MIME type for the given extension or null iff there is none.
523     */
524    public static String guessMimeTypeFromExtension(String extension) {
525        if (extension == null || extension.isEmpty()) {
526            return null;
527        }
528        return extensionToMimeTypeMap.get(extension.toLowerCase());
529    }
530
531    /**
532     * Returns true if the given extension has a registered MIME type.
533     *
534     * @param extension A file extension without the leading '.'
535     * @return True iff there is an extension entry in the map.
536     */
537    public static boolean hasExtension(String extension) {
538        if (extension == null || extension.isEmpty()) {
539            return false;
540        }
541        return extensionToMimeTypeMap.containsKey(extension);
542    }
543
544    /**
545     * Returns the registered extension for the given MIME type. Note that some MIME types map to
546     * multiple extensions. This call will return the most common extension for the given MIME type.
547     *
548     * @param mimeType A MIME type (i.e. text/plain)
549     * @return The extension for the given MIME type or null iff there is none.
550     */
551    public static String guessExtensionFromMimeType(String mimeType) {
552        if (mimeType == null || mimeType.isEmpty()) {
553            return null;
554        }
555        return mimeTypeToExtensionMap.get(mimeType.split(";")[0]);
556    }
557
558    public static String guessMimeTypeFromUriAndMime(
559            final Context context, final Uri uri, final String mime) {
560        Log.d(Config.LOGTAG, "guessMimeTypeFromUriAndMime(" + uri + "," + mime + ")");
561        final String mimeFromUri = guessMimeTypeFromUri(context, uri);
562        Log.d(Config.LOGTAG, "mimeFromUri:" + mimeFromUri);
563        if (PATH_PRECEDENCE_MIME_TYPE.contains(mimeFromUri)) {
564            return mimeFromUri;
565        } else if (mime == null || mime.equals("application/octet-stream")) {
566            return mimeFromUri;
567        } else {
568            return mime;
569        }
570    }
571
572    public static String guessMimeTypeFromUri(final Context context, final Uri uri) {
573        if ("data".equals(uri.getScheme())) {
574            String[] parts = uri.getSchemeSpecificPart().split(",", 2);
575            String[] parts2 = parts[0].split(";", 2);
576            if (parts2.length > 0) return parts2[0];
577        }
578        final String mimeTypeContentResolver = guessFromContentResolver(context, uri);
579        final String mimeTypeFromQueryParameter = uri.isHierarchical() ? uri.getQueryParameter("mimeType") : null;
580        final String name = "content".equals(uri.getScheme()) ? getDisplayName(context, uri) : null;
581        final String mimeTypeFromName = Strings.isNullOrEmpty(name) ? null : guessFromPath(name);
582        final String path = uri.getPath();
583        final String mimeTypeFromPath = Strings.isNullOrEmpty(path) ? null : guessFromPath(path);
584        if (PATH_PRECEDENCE_MIME_TYPE.contains(mimeTypeFromName)) {
585            return mimeTypeFromName;
586        }
587        if (PATH_PRECEDENCE_MIME_TYPE.contains(mimeTypeFromPath)) {
588            return mimeTypeFromPath;
589        }
590        if (mimeTypeContentResolver != null
591                && !"application/octet-stream".equals(mimeTypeContentResolver)) {
592            return mimeTypeContentResolver;
593        }
594        if (mimeTypeFromName != null) {
595            return mimeTypeFromName;
596        }
597        if (mimeTypeFromQueryParameter != null) {
598            return mimeTypeFromQueryParameter;
599        }
600        return mimeTypeFromPath;
601    }
602
603    private static String guessFromContentResolver(final Context context, final Uri uri) {
604        try {
605            return context.getContentResolver().getType(uri);
606        } catch (final Throwable e) {
607            return null;
608        }
609    }
610
611    private static String getDisplayName(final Context context, final Uri uri) {
612        try (final Cursor cursor =
613                context.getContentResolver().query(uri, null, null, null, null)) {
614            if (cursor != null && cursor.moveToFirst()) {
615                final int index = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
616                if (index == -1) {
617                    return null;
618                }
619                return cursor.getString(index);
620            }
621        } catch (final Exception e) {
622            return null;
623        }
624        return null;
625    }
626
627    public static String guessFromPath(final String path) {
628        final int start = path.lastIndexOf('.') + 1;
629        if (start < path.length()) {
630            return MimeUtils.guessMimeTypeFromExtension(path.substring(start));
631        }
632        return null;
633    }
634
635    public static String extractRelevantExtension(final String path) {
636        return extractRelevantExtension(path, false);
637    }
638
639    public static String extractRelevantExtension(
640            final String path, final boolean ignoreCryptoExtension) {
641        if (Strings.isNullOrEmpty(path)) {
642            return null;
643        }
644
645        final String filenameQueryAnchor = path.substring(path.lastIndexOf('/') + 1);
646        final String filenameQuery = cutBefore(filenameQueryAnchor, '#');
647        final String filename = cutBefore(filenameQuery, '?');
648        final int dotPosition = filename.lastIndexOf('.');
649
650        if (dotPosition == -1) {
651            return null;
652        }
653        final String extension = filename.substring(dotPosition + 1);
654        // we want the real file extension, not the crypto one
655        if (ignoreCryptoExtension && Transferable.VALID_CRYPTO_EXTENSIONS.contains(extension)) {
656            return extractRelevantExtension(filename.substring(0, dotPosition));
657        } else {
658            return extension;
659        }
660    }
661
662    private static String cutBefore(final String input, final char c) {
663        final int position = input.indexOf(c);
664        if (position > 0) {
665            return input.substring(0, position);
666        } else {
667            return input;
668        }
669    }
670}