Android Question Strange behavior with API29 and loading file from external storage

KZero · Apr 13, 2020

I'm using runtime permission

When I try to load an image from external storage on target API29 I get Permission denied error

the same code works fine on target API28 or less

the problem only occurs when the first install is targeting API29, if the app was installed with an older API then installed a new version with API29 no problems

B4X:

** Activity (main) Resume **
Error occurred on line: 183 (Main)
java.io.FileNotFoundException: /storage/emulated/0/1.jpg: open failed: EACCES (Permission denied)
    at libcore.io.IoBridge.open(IoBridge.java:496)
    at java.io.FileInputStream.<init>(FileInputStream.java:159)
    at anywheresoftware.b4a.objects.streams.File.OpenInput(File.java:214)
    at anywheresoftware.b4a.objects.drawable.CanvasWrapper$BitmapWrapper.initializeSampleImpl(CanvasWrapper.java:601)
    at anywheresoftware.b4a.objects.drawable.CanvasWrapper$BitmapWrapper.InitializeResize(CanvasWrapper.java:548)
    at anywheresoftware.b4a.keywords.Common.LoadBitmapResize(Common.java:1371)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
    at anywheresoftware.b4a.keywords.Common.CallSub4(Common.java:1083)
    at anywheresoftware.b4a.keywords.Common.CallSubNew2(Common.java:1038)
    at k0.zgridview.zgridview._sv_scrollchanged(zgridview.java:669)
    at k0.zgridview.zgridview$ResumableSub_Reload.resume(zgridview.java:486)
    at anywheresoftware.b4a.keywords.Common$13.run(Common.java:1705)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:237)
    at android.app.ActivityThread.main(ActivityThread.java:8016)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1076)
Caused by: android.system.ErrnoException: open failed: EACCES (Permission denied)
    at libcore.io.Linux.open(Native Method)
    at libcore.io.ForwardingOs.open(ForwardingOs.java:167)
    at libcore.io.BlockGuardOs.open(BlockGuardOs.java:252)
    at libcore.io.ForwardingOs.open(ForwardingOs.java:167

DonManfred · Apr 13, 2020

Android 10 for Developers | Android Developers

developer.android.com

Securing user data in external storage - Android 10 introduces a number of changes to give users more control over files in external storage and the app data within them. Apps can store their own files in their private sandboxes, but must use MediaStore to access shared media files and use the system file picker to access shared files in the new Downloads collection. Learn more here.

I guess this applies to the internal sdcard too now.

Erel · Apr 13, 2020

targetSdkVersion should be set to 28 for now.

DonManfred · Apr 13, 2020

You can try this example. It shows on how to access the app specific Folders to which you have access without a special permission. Even on Targetsdk 29.
The files are not at the root of the sdcard though ;-)

And you should follow the suggestion not to set it to 29 for now.

But if you want to test it out of curiosity. Here you are:

I´ve added a constants Object to the Storage library (It is the 1st Library i ever published btw).

B4X:

    @ShortName("StorageConstants")
  public static final class StorageConstants {
        public static final String DIRECTORY_ALARMS =     Environment.DIRECTORY_ALARMS;
        public static final String DIRECTORY_DCIM =     Environment.DIRECTORY_DCIM;
        public static final String DIRECTORY_DOCUMENTS =     Environment.DIRECTORY_DOCUMENTS;
        public static final String DIRECTORY_DOWNLOADS =     Environment.DIRECTORY_DOWNLOADS;
        public static final String DIRECTORY_MOVIES =     Environment.DIRECTORY_MOVIES;
        public static final String DIRECTORY_MUSIC =     Environment.DIRECTORY_MUSIC;
        public static final String DIRECTORY_NOTIFICATIONS =     Environment.DIRECTORY_NOTIFICATIONS;
        public static final String DIRECTORY_PICTURES =     Environment.DIRECTORY_PICTURES;
        public static final String DIRECTORY_PODCASTS =     Environment.DIRECTORY_PODCASTS;
        public static final String DIRECTORY_RINGTONES =     Environment.DIRECTORY_RINGTONES;

    }

In the example i get the DIRECTORY_PICTURES folder and here i do create a Album named MySpecialAlbum and then i copy a file from the asssets to this folder.
At the last action i do a ListFiles on this Folder.

B4X:

    Dim myalbum As String = storage.getAppSpecificAlbumStorageDir(stc.DIRECTORY_PICTURES,"MySpecialAlbum")
    Log("MySpecialAlbum path="&myalbum)
    File.Copy(File.DirAssets,"donmanfred.png",myalbum,"donmanfred.png")

    For Each f As String In File.ListFiles(myalbum)
        Log(">"&f)
    Next

>donmanfred.png

KZero · Apr 13, 2020

DonManfred said:
You can try this example. It shows on how to access the app specific Folders to which you have access without a special permission. Even on Targetsdk 29.
The files are not at the root of the sdcard though ;-)

And you should follow the suggestion not to set it to 29 for now.

But if you want to test it out of curiosity. Here you are:

I´ve added a constants Object to the Storage library (It is the 1st Library i ever published btw).

B4X:

@ShortName("StorageConstants") public static final class StorageConstants { public static final String DIRECTORY_ALARMS = Environment.DIRECTORY_ALARMS; public static final String DIRECTORY_DCIM = Environment.DIRECTORY_DCIM; public static final String DIRECTORY_DOCUMENTS = Environment.DIRECTORY_DOCUMENTS; public static final String DIRECTORY_DOWNLOADS = Environment.DIRECTORY_DOWNLOADS; public static final String DIRECTORY_MOVIES = Environment.DIRECTORY_MOVIES; public static final String DIRECTORY_MUSIC = Environment.DIRECTORY_MUSIC; public static final String DIRECTORY_NOTIFICATIONS = Environment.DIRECTORY_NOTIFICATIONS; public static final String DIRECTORY_PICTURES = Environment.DIRECTORY_PICTURES; public static final String DIRECTORY_PODCASTS = Environment.DIRECTORY_PODCASTS; public static final String DIRECTORY_RINGTONES = Environment.DIRECTORY_RINGTONES; }

In the example i get the DIRECTORY_PICTURES folder and here i do create a Album named MySpecialAlbum and then i copy a file from the asssets to this folder.
At the last action i do a ListFiles on this Folder.

B4X:

Dim myalbum As String = storage.getAppSpecificAlbumStorageDir(stc.DIRECTORY_PICTURES,"MySpecialAlbum") Log("MySpecialAlbum path="&myalbum) File.Copy(File.DirAssets,"donmanfred.png",myalbum,"donmanfred.png") For Each f As String In File.ListFiles(myalbum) Log(">"&f) Next

Thanks for sharing this library
I will stick with API28 for now but I couldn't wait to test the library and read about the new scoped access in Android 10, this lib will be a must for the new API ?

DonManfred · Apr 13, 2020

I´m not sure if it is different to the path you get using rp.GetSafeDirDefaultExternal(path)
Probably it is the same

Mahares · Apr 13, 2020

KZero said:
Android 10, this lib will be a must for the new API

Not so fast. @Erel has always found a way to make things work when the time is ripe and API 29 is required without the use of additional libraries.

Android Question Strange behavior with API29 and loading file from external storage

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