pass context as parameter instead of risk of leaking memory

Also adjust to dynamic permissions after bumping target-SDK.

There still is some confusion about the concept of "external storage" in
the code. LocalDocuments already is "external storage" - clean that up a
little and use AppCompat function instead of using a legacy class for
ExternalDocuments provider.
Doesn't help for broken ROMs though, that would need guessing pathname
for a mounted SD (in addition to separate storage partition of builtin
storage).

Also c6e8c96d50fc2082a3c4b9553196a42bbdd6df37 incorrectly changed the
conditional around, making the whole ExternalDocumentsProvider useless/a
copy of the Local one (i.e. the primary, first returned by the system).
Real fix for tdf#99539 likely was 66be4feef7e0d3661f01fbb2372700de5eeea070

Change-Id: I88ca7742c0f2e89d63c338c8852ad88be0a46e4b
Reviewed-on: https://gerrit.libreoffice.org/45572
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Christian Lohmaier <lohmaier+LibreOffice@googlemail.com>

18 files changed, 158 insertions, 206 deletions

diff --git a/android/source/res/menu/navigation_menu.xml b/android/source/res/menu/navigation_menu.xml
index 532c9ed60639..db680a9a1b8c 100644
--- a/android/source/res/menu/navigation_menu.xml
+++ b/android/source/res/menu/navigation_menu.xml
@@ -6,7 +6,7 @@
 
         <item android:id="@+id/menu_provider_documents"
             android:title="@string/local_documents"
-            android:icon="@drawable/ic_insert_drive_file_black_24dp" />
+            android:icon="@drawable/ic_folder_black_24dp" />
 
         <item android:id="@+id/menu_provider_filesystem"
             android:title="@string/local_file_system"
diff --git a/android/source/res/values/strings.xml b/android/source/res/values/strings.xml
index db06d3e2a7cc..5d7eca869a39 100644
--- a/android/source/res/values/strings.xml
+++ b/android/source/res/values/strings.xml
@@ -69,7 +69,7 @@
     <!-- Document provider names -->
     <string name="document_locations">Document locations</string>
     <string name="close_document_locations">Close document locations</string>
-    <string name="local_documents">Local documents</string>
+    <string name="local_documents">Documents directory</string>
     <string name="local_file_system">Local file system</string>
     <string name="external_sd_file_system">External SD</string>
     <string name="otg_file_system">OTG device (experimental)</string>
diff --git a/android/source/src/java/org/libreoffice/LibreOfficeMainActivity.java b/android/source/src/java/org/libreoffice/LibreOfficeMainActivity.java
index 534eaf44de59..48722dcd9bfd 100644
--- a/android/source/src/java/org/libreoffice/LibreOfficeMainActivity.java
+++ b/android/source/src/java/org/libreoffice/LibreOfficeMainActivity.java
@@ -323,7 +323,7 @@ public class LibreOfficeMainActivity extends AppCompatActivity implements Settin
                 try {
                     // rebuild the IFile object from the data passed in the Intent
                     IFile mStorageFile = DocumentProviderFactory.getInstance()
-                            .getProvider(providerId).createFromUri(documentUri);
+                            .getProvider(providerId).createFromUri(LibreOfficeMainActivity.this, documentUri);
                     // call document provider save operation
                     mStorageFile.saveDocument(mInputFile);
                 }
diff --git a/android/source/src/java/org/libreoffice/storage/DocumentProviderFactory.java b/android/source/src/java/org/libreoffice/storage/DocumentProviderFactory.java
index f73a2b0d543a..acf5aebcd6c6 100644
--- a/android/source/src/java/org/libreoffice/storage/DocumentProviderFactory.java
+++ b/android/source/src/java/org/libreoffice/storage/DocumentProviderFactory.java
@@ -13,7 +13,6 @@ import java.util.HashSet;
 import java.util.Set;
 
 import org.libreoffice.storage.external.ExtsdDocumentsProvider;
-import org.libreoffice.storage.external.LegacyExtSDDocumentsProvider;
 import org.libreoffice.storage.external.OTGDocumentsProvider;
 import org.libreoffice.storage.local.LocalDocumentsDirectoryProvider;
 import org.libreoffice.storage.local.LocalDocumentsProvider;
@@ -21,7 +20,6 @@ import org.libreoffice.storage.owncloud.OwnCloudProvider;
 
 import android.content.Context;
 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
-import android.os.Build;
 
 /**
  * Keeps the instances of the available IDocumentProviders in the system.
@@ -68,13 +66,7 @@ public final class DocumentProviderFactory {
             instance.providers[OTG_PROVIDER_INDEX] = new OTGDocumentsProvider(OTG_PROVIDER_INDEX, context);
             instance.providers[4] = new OwnCloudProvider(4, context);
 
-            if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
-                instance.providers[EXTSD_PROVIDER_INDEX]
-                        = new ExtsdDocumentsProvider(EXTSD_PROVIDER_INDEX, context);
-            } else {
-                instance.providers[EXTSD_PROVIDER_INDEX]
-                        = new LegacyExtSDDocumentsProvider(EXTSD_PROVIDER_INDEX, context);
-            }
+            instance.providers[EXTSD_PROVIDER_INDEX] = new ExtsdDocumentsProvider(EXTSD_PROVIDER_INDEX, context);
 
             // initialize document provider names list
             instance.providerNames = new String[instance.providers.length];
@@ -121,7 +113,7 @@ public final class DocumentProviderFactory {
      * @return default provider.
      */
     public IDocumentProvider getDefaultProvider() {
-        return providers[1];
+        return providers[0];
     }
 
     public Set<OnSharedPreferenceChangeListener> getChangeListeners() {
diff --git a/android/source/src/java/org/libreoffice/storage/IDocumentProvider.java b/android/source/src/java/org/libreoffice/storage/IDocumentProvider.java
index 2b0460a8ee6e..044d7ddb422b 100644
--- a/android/source/src/java/org/libreoffice/storage/IDocumentProvider.java
+++ b/android/source/src/java/org/libreoffice/storage/IDocumentProvider.java
@@ -9,6 +9,8 @@
 
 package org.libreoffice.storage;
 
+import android.content.Context;
+
 import java.net.URI;
 
 /**
@@ -22,19 +24,22 @@ public interface IDocumentProvider {
      *
      * @return Content root element.
      * @throws RuntimeException in case of error.
+     * @param context
      */
-    IFile getRootDirectory();
+    IFile getRootDirectory(Context context);
 
     /**
      * Transforms some URI into the IFile object that represents that content.
      *
+     *
+     * @param context
      * @param uri
      *            URI pointing to some content object that has been previously
      *            retrieved with IFile.getUri().
      * @return IFile object pointing to the content represented by uri.
      * @throws RuntimeException in case of error.
      */
-    IFile createFromUri(URI uri);
+    IFile createFromUri(Context context, URI uri);
 
     /**
      * Get internationalized name for this provider. This name is intended to be
@@ -59,6 +64,7 @@ public interface IDocumentProvider {
      * Checks if the Document Provider is available or not.
      *
      * @return A boolean value based on provider availability.
+     * @param context
      */
-    boolean checkProviderAvailability();
+    boolean checkProviderAvailability(Context context);
 }
diff --git a/android/source/src/java/org/libreoffice/storage/IFile.java b/android/source/src/java/org/libreoffice/storage/IFile.java
index 3655ba484ede..c9cfa7f1198d 100644
--- a/android/source/src/java/org/libreoffice/storage/IFile.java
+++ b/android/source/src/java/org/libreoffice/storage/IFile.java
@@ -9,6 +9,8 @@
 
 package org.libreoffice.storage;
 
+import android.content.Context;
+
 import java.io.File;
 import java.io.FileFilter;
 import java.net.URI;
@@ -91,8 +93,9 @@ public interface IFile {
      * Returns the pparent of this file.
      *
      * @return this file's parent or null if it does not have it.
+     * @param context
      */
-    IFile getParent();
+    IFile getParent(Context context);
 
     /**
      * Returns the document wrapped by this IFile as a local file. The result
diff --git a/android/source/src/java/org/libreoffice/storage/external/BrowserSelectorActivity.java b/android/source/src/java/org/libreoffice/storage/external/BrowserSelectorActivity.java
index fe12804e620c..90a15ae95af4 100644
--- a/android/source/src/java/org/libreoffice/storage/external/BrowserSelectorActivity.java
+++ b/android/source/src/java/org/libreoffice/storage/external/BrowserSelectorActivity.java
@@ -64,7 +64,7 @@ public class BrowserSelectorActivity extends AppCompatActivity {
         IExternalDocumentProvider provider =
                 (IExternalDocumentProvider) DocumentProviderFactory.getInstance()
                         .getProvider(providerIndex);
-        String previousDirectoryPath = preferences.getString(preferenceKey, provider.guessRootURI());
+        String previousDirectoryPath = preferences.getString(preferenceKey, provider.guessRootURI(this));
         Intent i = new Intent(this, DirectoryBrowserActivity.class);
         i.putExtra(DirectoryBrowserActivity.DIRECTORY_PATH_EXTRA, previousDirectoryPath);
         startActivityForResult(i, REQUEST_INTERNAL_BROWSER);
diff --git a/android/source/src/java/org/libreoffice/storage/external/ExternalFile.java b/android/source/src/java/org/libreoffice/storage/external/ExternalFile.java
index 7c7f09fc1ade..aff33e4413ef 100644
--- a/android/source/src/java/org/libreoffice/storage/external/ExternalFile.java
+++ b/android/source/src/java/org/libreoffice/storage/external/ExternalFile.java
@@ -102,11 +102,11 @@ public class ExternalFile implements IFile{
     }
 
     @Override
-    public IFile getParent() {
+    public IFile getParent(Context context) {
         // this is the root node
         if(docFile.getParentFile() == null) return null;
 
-        return new ExternalFile(provider, docFile.getParentFile(), context);
+        return new ExternalFile(provider, docFile.getParentFile(), this.context);
     }
 
     @Override
diff --git a/android/source/src/java/org/libreoffice/storage/external/ExtsdDocumentsProvider.java b/android/source/src/java/org/libreoffice/storage/external/ExtsdDocumentsProvider.java
index 4ce77f0e1916..72599ec0d17b 100644
--- a/android/source/src/java/org/libreoffice/storage/external/ExtsdDocumentsProvider.java
+++ b/android/source/src/java/org/libreoffice/storage/external/ExtsdDocumentsProvider.java
@@ -1,6 +1,5 @@
 package org.libreoffice.storage.external;
 
-import android.annotation.TargetApi;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
@@ -8,7 +7,9 @@ import android.net.Uri;
 import android.os.Build;
 import android.os.Environment;
 import android.preference.PreferenceManager;
+import android.support.v4.content.ContextCompat;
 import android.support.v4.provider.DocumentFile;
+import android.util.Log;
 
 import org.libreoffice.R;
 import org.libreoffice.storage.DocumentProviderSettingsActivity;
@@ -34,45 +35,49 @@ public class ExtsdDocumentsProvider implements IExternalDocumentProvider,
 
     private int id;
     private File cacheDir;
-    private Context context;
     private String rootPathURI;
 
     public ExtsdDocumentsProvider(int id, Context context) {
         this.id = id;
-        this.context = context;
-        setupRootPathUri();
-        setupCache();
+        setupRootPathUri(context);
+        setupCache(context);
     }
 
-    private void setupRootPathUri() {
+    private void setupRootPathUri(Context context) {
         SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
-        String rootURIGuess = guessRootURI();
         rootPathURI = preferences.getString(
-                DocumentProviderSettingsActivity.KEY_PREF_EXTERNAL_SD_PATH_URI, rootURIGuess);
+                DocumentProviderSettingsActivity.KEY_PREF_EXTERNAL_SD_PATH_URI, guessRootURI(context));
     }
 
-    //Android 4.4 specific
-    @TargetApi(Build.VERSION_CODES.KITKAT)
-    public String guessRootURI() {
-        File[] options = context.getExternalFilesDirs(null);
-        File internalSD = Environment.getExternalStorageDirectory();
-        String internalSDPath = internalSD.getAbsolutePath();
-
-        for (File option: options) {
+    public String guessRootURI(Context context) {
+        // TODO: unfortunately the getExternalFilesDirs function relies on devices to actually
+        // follow guidelines re external storage. Of course device manufacturers don't and as such
+        // you cannot rely on it returning the actual paths (neither the compat, nor the native variant)
+        File[] possibleRemovables = ContextCompat.getExternalFilesDirs(context,null);
+        // the primary dir that is already covered by the "LocalDocumentsProvider"
+        // might be emulated/part of internal memory or actual SD card
+        // TODO: change to not confuse android's "external storage" with "expandable storage"
+        String primaryExternal = Environment.getExternalStorageDirectory().getAbsolutePath();
+
+        for (File option: possibleRemovables) {
             // Returned paths may be null if a storage device is unavailable.
-            if (null == option) { continue; }
-
+            if (null == option) {
+                Log.w(LOGTAG,"path was a null option :-/"); continue; }
             String optionPath = option.getAbsolutePath();
+            if(optionPath.contains(primaryExternal)) {
+                Log.v(LOGTAG, "did get file path - but is same as primary storage ("+ primaryExternal +")");
+                continue;
+            }
 
-            if(optionPath.contains(internalSDPath))
-                return option.toURI().toString();
-
+            return option.toURI().toString();
         }
 
-        return "";
+        // TODO: do some manual probing of possible directories (/storage/sdcard1 and similar)
+        Log.i(LOGTAG, "no secondary storage reported");
+        return null;
     }
 
-    private void setupCache() {
+    private void setupCache(Context context) {
         // TODO: probably we should do smarter cache management
         cacheDir = new File(context.getExternalCacheDir(), "externalFiles");
         if (cacheDir.exists()) {
@@ -94,41 +99,42 @@ public class ExtsdDocumentsProvider implements IExternalDocumentProvider,
     }
 
     @Override
-    public IFile getRootDirectory() {
+    public IFile getRootDirectory(Context context) {
         if(android.os.Build.VERSION.SDK_INT <= Build.VERSION_CODES.KITKAT) {
-            return android4RootDirectory();
+            return android4RootDirectory(context);
         } else {
-            return android5RootDirectory();
+            return android5RootDirectory(context);
         }
     }
 
-    private ExternalFile android4RootDirectory() {
+    private ExternalFile android4RootDirectory(Context context) {
         try{
             File f = new File(new URI(rootPathURI));
             return new ExternalFile(this, DocumentFile.fromFile(f), context);
         } catch (Exception e) {
             //invalid rootPathURI
-            throw buildRuntimeExceptionForInvalidFileURI();
+            throw buildRuntimeExceptionForInvalidFileURI(context);
         }
     }
 
-    private ExternalFile android5RootDirectory() {
+    private ExternalFile android5RootDirectory(Context context) {
         try {
             return new ExternalFile(this,
                                     DocumentFile.fromTreeUri(context, Uri.parse(rootPathURI)),
                                     context);
         } catch (Exception e) {
             //invalid rootPathURI
-            throw buildRuntimeExceptionForInvalidFileURI();
+            throw buildRuntimeExceptionForInvalidFileURI(context);
         }
     }
 
-    private RuntimeException buildRuntimeExceptionForInvalidFileURI() {
+    private RuntimeException buildRuntimeExceptionForInvalidFileURI(Context context) {
+        // ToDo: discarding the original excpeption / catch-all handling is bad style
         return new RuntimeException(context.getString(R.string.ext_document_provider_error));
     }
 
     @Override
-    public IFile createFromUri(URI javaURI) {
+    public IFile createFromUri(Context context, URI javaURI) {
         //TODO: refactor when new DocumentFile API exist
         //uri must be of a DocumentFile file, not directory.
         Uri androidUri = Uri.parse(javaURI.toString());
@@ -148,8 +154,13 @@ public class ExtsdDocumentsProvider implements IExternalDocumentProvider,
     }
 
     @Override
-    public boolean checkProviderAvailability() {
-        return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED) && Environment.isExternalStorageRemovable();
+    public boolean checkProviderAvailability(Context context) {
+        // too many devices (or I am just unlucky) don't report the mounted state properly, and other
+        // devices also consider dedicated part of internal storage to be "mounted" so cannot use
+        // getExternalStorageState().equals(Environment.MEDIA_MOUNTED) && isExternalStorageRemovable()
+        // but they refer to the primary external storage anyway, so what currently is covered by the
+        // "LocalDocumentsProvider"
+        return rootPathURI!=null;
     }
 
     @Override
diff --git a/android/source/src/java/org/libreoffice/storage/external/IExternalDocumentProvider.java b/android/source/src/java/org/libreoffice/storage/external/IExternalDocumentProvider.java
index 34bbcbc4bad6..a439417b60cd 100644
--- a/android/source/src/java/org/libreoffice/storage/external/IExternalDocumentProvider.java
+++ b/android/source/src/java/org/libreoffice/storage/external/IExternalDocumentProvider.java
@@ -1,5 +1,7 @@
 package org.libreoffice.storage.external;
 
+import android.content.Context;
+
 import org.libreoffice.storage.IDocumentProvider;
 
 
@@ -13,7 +15,8 @@ public interface IExternalDocumentProvider extends IDocumentProvider {
      * browsing using the internal DirectoryBrowser.
      *
      * @return a guess of the root file's URI.
+     * @param context
      */
-    String guessRootURI();
+    String guessRootURI(Context context);
 
 }
diff --git a/android/source/src/java/org/libreoffice/storage/external/LegacyExtSDDocumentsProvider.java b/android/source/src/java/org/libreoffice/storage/external/LegacyExtSDDocumentsProvider.java
deleted file mode 100644
index 1ac34405b361..000000000000
--- a/android/source/src/java/org/libreoffice/storage/external/LegacyExtSDDocumentsProvider.java
+++ /dev/null
@@ -1,103 +0,0 @@
-package org.libreoffice.storage.external;
-
-import android.content.Context;
-import android.content.SharedPreferences;
-import android.os.Environment;
-import android.preference.PreferenceManager;
-import android.text.TextUtils;
-import android.util.Log;
-
-import org.libreoffice.R;
-import org.libreoffice.storage.DocumentProviderSettingsActivity;
-import org.libreoffice.storage.IFile;
-import org.libreoffice.storage.IOUtils;
-import org.libreoffice.storage.local.LocalFile;
-
-import java.io.File;
-import java.net.URI;
-
-/**
- * Legacy document provider for External SD cards, for Android 4.3 and below.
- *
- * Uses the LocalFile class.
- */
-public class LegacyExtSDDocumentsProvider implements IExternalDocumentProvider,
-        SharedPreferences.OnSharedPreferenceChangeListener{
-    private static final String LOGTAG = LegacyExtSDDocumentsProvider.class.getSimpleName();
-
-    private int id;
-    private Context context;
-    private String rootPathURI;
-
-    public LegacyExtSDDocumentsProvider(int id, Context context) {
-        this.id = id;
-        this.context = context;
-        setupRootPathUri();
-    }
-
-    private void setupRootPathUri() {
-        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
-        String rootURIGuess = guessRootURI();
-
-        rootPathURI = preferences.getString(
-                DocumentProviderSettingsActivity.KEY_PREF_EXTERNAL_SD_PATH_URI, rootURIGuess);
-    }
-
-    public String guessRootURI() {
-        //hacky method of obtaining extsdcard root
-        final String value = System.getenv("SECONDARY_STORAGE");
-        Log.d(LOGTAG, "guesses: " + value);
-        if (!TextUtils.isEmpty(value)) {
-            final String[] paths = value.split(":");
-            for (String path : paths) {
-                File file = new File(path);
-                if(path.contains("ext") && file.isDirectory()) {
-                    return file.toURI().toString();
-                }
-            }
-        }
-        return "";
-    }
-
-    @Override
-    public IFile getRootDirectory() {
-        if(rootPathURI.equals("")) {
-            throw new RuntimeException(context.getString(R.string.ext_document_provider_error));
-        }
-
-        File f = IOUtils.getFileFromURIString(rootPathURI);
-        if(IOUtils.isInvalidFile(f)) {
-            //missing device
-            throw new RuntimeException(context.getString(R.string.legacy_extsd_missing_error));
-        }
-        return new LocalFile(f);
-    }
-
-    @Override
-    public IFile createFromUri(URI uri) {
-        return new LocalFile(uri);
-    }
-
-    @Override
-    public int getNameResource() {
-        return R.string.external_sd_file_system;
-    }
-
-    @Override
-    public int getId() {
-        return id;
-    }
-
-    @Override
-    public boolean checkProviderAvailability() {
-        return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED) && Environment.isExternalStorageRemovable();
-    }
-
-    @Override
-    public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
-        if (key.equals(DocumentProviderSettingsActivity.KEY_PREF_EXTERNAL_SD_PATH_URI)) {
-            rootPathURI = preferences.getString(key, "");
-        }
-    }
-
-}
diff --git a/android/source/src/java/org/libreoffice/storage/external/OTGDocumentsProvider.java b/android/source/src/java/org/libreoffice/storage/external/OTGDocumentsProvider.java
index d4ce3492c1ea..138ec9479755 100644
--- a/android/source/src/java/org/libreoffice/storage/external/OTGDocumentsProvider.java
+++ b/android/source/src/java/org/libreoffice/storage/external/OTGDocumentsProvider.java
@@ -4,6 +4,7 @@ import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.preference.PreferenceManager;
+import android.util.Log;
 
 import org.libreoffice.R;
 import org.libreoffice.storage.DocumentProviderSettingsActivity;
@@ -22,24 +23,22 @@ public class OTGDocumentsProvider implements IExternalDocumentProvider,
 
     private static final String LOGTAG = OTGDocumentsProvider.class.getSimpleName();
 
-    private Context context;
     private String rootPathURI;
     private int id;
 
     public OTGDocumentsProvider(int id, Context context) {
-        this.context = context;
         this.id = id;
-        setupRootPath();
+        setupRootPath(context);
     }
 
-    private void setupRootPath() {
+    private void setupRootPath(Context context) {
         SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
         rootPathURI = preferences.getString(
                 DocumentProviderSettingsActivity.KEY_PREF_OTG_PATH_URI, "");
     }
 
     @Override
-    public IFile createFromUri(URI uri) {
+    public IFile createFromUri(Context context, URI uri) {
         return new LocalFile(uri);
     }
 
@@ -54,15 +53,16 @@ public class OTGDocumentsProvider implements IExternalDocumentProvider,
     }
 
     @Override
-    public IFile getRootDirectory() {
-
+    public IFile getRootDirectory(Context context) {
+        // TODO: handle this with more fine-grained exceptions
         if(rootPathURI.equals("")) {
+            Log.e(LOGTAG, "rootPathURI is empty");
             throw new RuntimeException(context.getString(R.string.ext_document_provider_error));
         }
 
         File f = IOUtils.getFileFromURIString(rootPathURI);
         if(IOUtils.isInvalidFile(f)) {
-            //missing device
+            Log.e(LOGTAG, "rootPathURI is invalid - missing device?");
             throw new RuntimeException(context.getString(R.string.otg_missing_error));
         }
 
@@ -78,12 +78,12 @@ public class OTGDocumentsProvider implements IExternalDocumentProvider,
     }
 
     @Override
-    public String guessRootURI() {
+    public String guessRootURI(Context context) {
         return "";
     }
 
     @Override
-    public boolean checkProviderAvailability() {
+    public boolean checkProviderAvailability(Context context) {
         // check if system supports USB Host
         return context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_USB_HOST);
     }
diff --git a/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsDirectoryProvider.java b/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsDirectoryProvider.java
index fb4236969cb2..02d58d329122 100644
--- a/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsDirectoryProvider.java
+++ b/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsDirectoryProvider.java
@@ -14,7 +14,13 @@ import java.io.File;
 import org.libreoffice.storage.IFile;
 import org.libreoffice.R;
 
+import android.Manifest;
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.os.Build;
 import android.os.Environment;
+import android.support.v4.content.ContextCompat;
+import android.util.Log;
 
 /**
  * A convenience IDocumentProvider to browse the /sdcard/Documents directory.
@@ -29,11 +35,31 @@ public class LocalDocumentsDirectoryProvider extends LocalDocumentsProvider {
         super(id);
     }
 
+    private static File getDocumentsDir() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            // DIRECTORY_DOCUMENTS is 19 or later only
+            return Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS);
+        } else {
+            return new File(Environment.getExternalStorageDirectory() + "/Documents");
+        }
+    }
+
     @Override
-    public IFile getRootDirectory() {
-        File documentsDirectory = new File(
-                Environment.getExternalStorageDirectory(), "Documents");
-        documentsDirectory.mkdirs();
+    public IFile getRootDirectory(Context context) {
+        File documentsDirectory = getDocumentsDir();
+        if (!documentsDirectory.exists()) {
+            // might be a little counter-intuitive: if we were granted READ permission already, we're also granted the write-permission
+            // when we ask for it, since they are both in the same storage group (for 5.1 and lower it is granted at install-time already)
+            // seehttps://developer.android.com/guide/topics/permissions/requesting.html#perm-groups
+            if (ContextCompat.checkSelfPermission(context, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
+                if(!documentsDirectory.mkdirs()) {
+                    // fallback to the toplevel dir - might be due to the dir not mounted/used as USB-Mass-Storage or similar
+                    // TODO: handle unavailability of the storage/failure of the mkdir properly
+                    Log.e("LocalDocumentsProvider", "not sure how we ended up here - if we have read permissions to use it in the first place, we also should have the write-permissions..");
+                    documentsDirectory = Environment.getExternalStorageDirectory();
+                }
+            }
+        }
         return new LocalFile(documentsDirectory);
     }
 
@@ -41,4 +67,10 @@ public class LocalDocumentsDirectoryProvider extends LocalDocumentsProvider {
     public int getNameResource() {
         return R.string.local_documents;
     }
+
+    @Override
+    public boolean checkProviderAvailability(Context context) {
+        File documentsDirectory = getDocumentsDir();
+        return documentsDirectory.exists() || ContextCompat.checkSelfPermission(context, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED;
+    }
 }
diff --git a/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsProvider.java b/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsProvider.java
index 42c253322ce7..39c91dc951e0 100644
--- a/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsProvider.java
+++ b/android/source/src/java/org/libreoffice/storage/local/LocalDocumentsProvider.java
@@ -16,6 +16,7 @@ import org.libreoffice.storage.IFile;
 
 import org.libreoffice.R;
 
+import android.content.Context;
 import android.os.Environment;
 
 /**
@@ -30,12 +31,12 @@ public class LocalDocumentsProvider implements IDocumentProvider {
     }
 
     @Override
-    public IFile getRootDirectory() {
+    public IFile getRootDirectory(Context context) {
         return new LocalFile(Environment.getExternalStorageDirectory());
     }
 
     @Override
-    public IFile createFromUri(URI uri) {
+    public IFile createFromUri(Context context, URI uri) {
         return new LocalFile(uri);
     }
 
@@ -50,7 +51,7 @@ public class LocalDocumentsProvider implements IDocumentProvider {
     }
 
     @Override
-    public boolean checkProviderAvailability() {
+    public boolean checkProviderAvailability(Context context) {
         return true;
     }
 }
diff --git a/android/source/src/java/org/libreoffice/storage/local/LocalFile.java b/android/source/src/java/org/libreoffice/storage/local/LocalFile.java
index 2d5554b419ee..4ff5bbf119f4 100644
--- a/android/source/src/java/org/libreoffice/storage/local/LocalFile.java
+++ b/android/source/src/java/org/libreoffice/storage/local/LocalFile.java
@@ -9,6 +9,8 @@
 
 package org.libreoffice.storage.local;
 
+import android.content.Context;
+
 import java.io.File;
 import java.io.FileFilter;
 import java.net.URI;
@@ -75,7 +77,7 @@ public class LocalFile implements IFile {
     }
 
     @Override
-    public IFile getParent() {
+    public IFile getParent(Context context) {
         return new LocalFile(file.getParentFile());
     }
 
diff --git a/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudFile.java b/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudFile.java
index c218961a2266..fa74a54b08e2 100644
--- a/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudFile.java
+++ b/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudFile.java
@@ -1,5 +1,7 @@
 package org.libreoffice.storage.owncloud;
 
+import android.content.Context;
+
 import java.io.File;
 import java.io.FileFilter;
 import java.io.UnsupportedEncodingException;
@@ -123,12 +125,12 @@ public class OwnCloudFile implements IFile {
     }
 
     @Override
-    public IFile getParent() {
+    public IFile getParent(Context context) {
         if (parentPath == null)
             // this is the root node
             return null;
 
-        return provider.createFromUri(URI.create(parentPath));
+        return provider.createFromUri(context, URI.create(parentPath));
     }
 
     @Override
diff --git a/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudProvider.java b/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudProvider.java
index e10c88bee93a..335a34aeb361 100644
--- a/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudProvider.java
+++ b/android/source/src/java/org/libreoffice/storage/owncloud/OwnCloudProvider.java
@@ -72,12 +72,12 @@ public class OwnCloudProvider implements IDocumentProvider,
     }
 
     @Override
-    public IFile getRootDirectory() {
-        return createFromUri(URI.create(FileUtils.PATH_SEPARATOR));
+    public IFile getRootDirectory(Context context) {
+        return createFromUri(context, URI.create(FileUtils.PATH_SEPARATOR));
     }
 
     @Override
-    public IFile createFromUri(URI uri) {
+    public IFile createFromUri(Context context, URI uri) {
         ReadRemoteFileOperation refreshOperation = new ReadRemoteFileOperation(
                 uri.getPath());
         RemoteOperationResult result = refreshOperation.execute(client);
@@ -179,7 +179,7 @@ public class OwnCloudProvider implements IDocumentProvider,
     }
 
     @Override
-    public boolean checkProviderAvailability() {
+    public boolean checkProviderAvailability(Context context) {
         return true;
     }
 }
diff --git a/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java b/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java
index 5b9dd0cc2ee0..f8d08aae171f 100644
--- a/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java
+++ b/android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java
@@ -9,6 +9,7 @@
 
 package org.libreoffice.ui;
 
+import android.Manifest;
 import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.BroadcastReceiver;
@@ -18,6 +19,7 @@ import android.content.DialogInterface;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.SharedPreferences;
+import android.content.pm.PackageManager;
 import android.content.pm.ShortcutInfo;
 import android.content.pm.ShortcutManager;
 import android.graphics.drawable.Icon;
@@ -30,6 +32,7 @@ import android.preference.PreferenceManager;
 import android.support.annotation.NonNull;
 import android.support.design.widget.FloatingActionButton;
 import android.support.design.widget.NavigationView;
+import android.support.v4.app.ActivityCompat;
 import android.support.v4.content.ContextCompat;
 import android.support.v4.view.ViewCompat;
 import android.support.v4.widget.DrawerLayout;
@@ -91,6 +94,8 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
     private int viewMode;
     private int sortMode;
     private boolean showHiddenFiles;
+    // dynamic permissions IDs
+    private static int PERMISSION_READ_EXTERNAL_STORAGE = 0;
 
     FileFilter fileFilter;
     FilenameFilter filenameFilter;
@@ -160,9 +165,20 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
         filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
         registerReceiver(mUSBReceiver, filter);
         // init UI and populate with contents from the provider
+        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
+            // TODO: remove local document providers if really is denied, code right now assumes it is granted/
+            // there is no onRequestPermissionsResult evaluating the callback
+            // without the read permissions, LO could only load documents passed via intent from other apps
+            Log.i(LOGTAG, "no permission to read external storage - asking for permission");
+            ActivityCompat.requestPermissions(this,
+                    new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
+                    PERMISSION_READ_EXTERNAL_STORAGE);
+        }
+
         switchToDocumentProvider(documentProviderFactory.getDefaultProvider());
         createUI();
-        getAnimations();
+        fabOpenAnimation = AnimationUtils.loadAnimation(this, R.anim.fab_open);
+        fabCloseAnimation = AnimationUtils.loadAnimation(this, R.anim.fab_close);
     }
 
     public void createUI() {
@@ -199,7 +215,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
         final ArrayList<IFile> recentFiles = new ArrayList<IFile>();
         for (String recentFileString : recentFileStrings) {
             try {
-                recentFiles.add(documentProvider.createFromUri(new URI(recentFileString)));
+                recentFiles.add(documentProvider.createFromUri(this, new URI(recentFileString)));
             } catch (URISyntaxException e) {
                 e.printStackTrace();
             } catch (RuntimeException e){
@@ -227,20 +243,16 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
         // Loop through the document providers menu items and check if they are available or not
         for (int index = 0; index < providerNames.size(); index++) {
             MenuItem item = navigationDrawer.getMenu().getItem(index);
-            boolean isDocumentProviderAvailable = checkDocumentProviderAvailability(documentProviderFactory.getProvider(index));
-            if (!isDocumentProviderAvailable){
-                item.setEnabled(false);
-            }
+            item.setEnabled(documentProviderFactory.getProvider(index).checkProviderAvailability(this));
         }
 
-        final Context context = this; //needed for anonymous method below
         navigationDrawer.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
             @Override
             public boolean onNavigationItemSelected(@NonNull MenuItem item) {
 
                 switch (item.getItemId()) {
                     case R.id.menu_storage_preferences: {
-                        startActivity(new Intent(context, DocumentProviderSettingsActivity.class));
+                        startActivity(new Intent(LibreOfficeUIActivity.this, DocumentProviderSettingsActivity.class));
                         return true;
                     }
 
@@ -300,11 +312,6 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
         drawerToggle.syncState();
     }
 
-    private void getAnimations() {
-        fabOpenAnimation = AnimationUtils.loadAnimation(this, R.anim.fab_open);
-        fabCloseAnimation = AnimationUtils.loadAnimation(this, R.anim.fab_close);
-    }
-
     private void expandFabMenu() {
         ViewCompat.animate(editFAB).rotation(45.0F).withLayer().setDuration(300).setInterpolator(new OvershootInterpolator(10.0F)).start();
         drawLayout.startAnimation(fabOpenAnimation);
@@ -331,10 +338,6 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
         isFabMenuOpen = false;
     }
 
-    private boolean checkDocumentProviderAvailability(IDocumentProvider provider) {
-        return provider.checkProviderAvailability();
-    }
-
     @Override
     protected void onPostCreate(Bundle savedInstanceState) {
         super.onPostCreate(savedInstanceState);
@@ -429,7 +432,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
                 // a different thread
                 try {
                     documentProvider = provider[0];
-                    homeDirectory = documentProvider.getRootDirectory();
+                    homeDirectory = documentProvider.getRootDirectory(LibreOfficeUIActivity.this);
                     currentDirectory = homeDirectory;
                     filePaths = currentDirectory.listFiles(FileUtilities
                             .getFileFilter(filterMode));
@@ -444,7 +447,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
                         }
                     });
                     startActivity(new Intent(activity, DocumentProviderSettingsActivity.class));
-                    Log.e(LOGTAG, e.getMessage(), e.getCause());
+                    Log.e(LOGTAG, "failed to switch document provider "+ e.getMessage(), e.getCause());
                 }
                 return null;
             }
@@ -613,7 +616,7 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
             protected IFile doInBackground(Void... dir) {
                 // this operation may imply network access and must be run in
                 // a different thread
-                return currentDirectory.getParent();
+                return currentDirectory.getParent(LibreOfficeUIActivity.this);
             }
 
             @Override
@@ -830,10 +833,10 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
         Intent i = this.getIntent();
         if (i.hasExtra(CURRENT_DIRECTORY_KEY)) {
             try {
-                currentDirectory = documentProvider.createFromUri(new URI(
+                currentDirectory = documentProvider.createFromUri(this, new URI(
                         i.getStringExtra(CURRENT_DIRECTORY_KEY)));
             } catch (URISyntaxException e) {
-                currentDirectory = documentProvider.getRootDirectory();
+                currentDirectory = documentProvider.getRootDirectory(this);
             }
             Log.d(LOGTAG, CURRENT_DIRECTORY_KEY);
         }
@@ -883,10 +886,10 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
                     .getProvider(savedInstanceState.getInt(DOC_PROVIDER_KEY));
         }
         try {
-            currentDirectory = documentProvider.createFromUri(new URI(
+            currentDirectory = documentProvider.createFromUri(this, new URI(
                     savedInstanceState.getString(CURRENT_DIRECTORY_KEY)));
         } catch (URISyntaxException e) {
-            currentDirectory = documentProvider.getRootDirectory();
+            currentDirectory = documentProvider.getRootDirectory(this);
         }
         filterMode = savedInstanceState.getInt(FILTER_MODE_KEY, FileUtilities.ALL);
         viewMode = savedInstanceState.getInt(EXPLORER_VIEW_TYPE_KEY, GRID_VIEW);