Andotp: "Export to external storage failed" when exporting to an external SD

[himselfv]

I'm using the latest version from the Play store, Android 8.0. I've configured the backups to use password and to add date to the name.

• Auto backup to external SD card (/storage/9106-4FE8/Folder) says "Export to external storage failed".
• Auto backup to internal SD card (/storage/emulated/0/Folder) works fine.
• Manual backup to any place works fine (and produces files).
• If I choose a non-existent folder on an external SD it says "Failed to create backup directory"

Log:

07-31 12:23:34.000 19829 19829 W System.err: java.io.FileNotFoundException: open failed: EACCES (Permission denied)
07-31 12:23:34.000 19829 19829 W System.err:    at android.os.ParcelFileDescriptor.openInternal(ParcelFileDescriptor.java:313)
07-31 12:23:34.000 19829 19829 W System.err:    at android.os.ParcelFileDescriptor.open(ParcelFileDescriptor.java:211)
07-31 12:23:34.000 19829 19829 W System.err:    at android.content.ContentResolver.openAssetFileDescriptor(ContentResolver.java:1248)
07-31 12:23:34.000 19829 19829 W System.err:    at android.content.ContentResolver.openOutputStream(ContentResolver.java:1013)
07-31 12:23:34.000 19829 19829 W System.err:    at android.content.ContentResolver.openOutputStream(ContentResolver.java:989)
07-31 12:23:34.000 19829 19829 W System.err:    at org.shadowice.flocke.andotp.Utilities.FileHelper.writeBytesToFile(FileHelper.java:117)
07-31 12:23:34.000 19829 19829 W System.err:    at org.shadowice.flocke.andotp.Activities.BackupActivity.doBackupCrypt(BackupActivity.java:468)
07-31 12:23:34.000 19829 19829 W System.err:    at org.shadowice.flocke.andotp.Activities.BackupActivity.showSaveFileSelector(BackupActivity.java:324)
07-31 12:23:34.000 19829 19829 W System.err:    at org.shadowice.flocke.andotp.Activities.BackupActivity.saveFileWithPermissions(BackupActivity.java:343)
07-31 12:23:34.000 19829 19829 W System.err:    at org.shadowice.flocke.andotp.Activities.BackupActivity.access$200(BackupActivity.java:67)
07-31 12:23:34.000 19829 19829 W System.err:    at org.shadowice.flocke.andotp.Activities.BackupActivity$3.onClick(BackupActivity.java:136)
07-31 12:23:34.000 19829 19829 W System.err:    at android.view.View.performClick(View.java:6897)
07-31 12:23:34.000 19829 19829 W System.err:    at android.view.View$PerformClick.run(View.java:26101)
07-31 12:23:34.000 19829 19829 W System.err:    at android.os.Handler.handleCallback(Handler.java:789)
07-31 12:23:34.000 19829 19829 W System.err:    at android.os.Handler.dispatchMessage(Handler.java:98)
07-31 12:23:34.000 19829 19829 W System.err:    at android.os.Looper.loop(Looper.java:164)
07-31 12:23:34.000 19829 19829 W System.err:    at android.app.ActivityThread.main(ActivityThread.java:6944)
07-31 12:23:34.000 19829 19829 W System.err:    at java.lang.reflect.Method.invoke(Native Method)
07-31 12:23:34.000 19829 19829 W System.err:    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327)
07-31 12:23:34.001 19829 19829 W System.err:    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)
07-31 12:23:34.017  3168  3201 V MARsPolicyManager: handelAlertToastWindowStarted pkgName = org.shadowice.flocke.andotp, userId = 0

Maybe this is the reason:
https://developer.android.com/guide/topics/providers/document-provider#permissions

I don't understand Android permission system well, but if I'm getting it right, I guess andOTP should ask for the "persistent backup folder" via some system intent, and then takePersistableUriPermission(FLAG_GRANT_PERSISTABLE_URI_PERMISSION | FLAG_GRANT_WRITE_URI_PERMISSION | FLAG_GRANT_PREFIX_URI_PERMISSION) ?

https://developer.android.com/reference/android/content/Intent#FLAG_GRANT_PREFIX_URI_PERMISSION

[RichyHBM]

Apps cant access the SD card storage unless under a specific folder (something like /Android/Data/com.flocke/andotp )

[himselfv]

@RichyHBM: but saving does work when I specify the file manually. It seems apps can access SD card, but they have to do the above dances.

[RichyHBM]

The issue here is that when selecting to save it manually andOTP passes the save operation onto the android file manager rather than saving it itself

[manuth]

@flocke I'm glad to see you're on track on this issue.
I'm facing exactly the same problem.

Neither automatically saving to /sdcard/, /sdcard/andOTP, /storage/emulated/0 nor /storage/emulated/0 work.

When creating an encrypted backup a notification pops up which says Export to external storage successful but no file is created actually.
When creating a plain-text backup a notification pops up which says Export to external storage failed.

When enabling Ask for filename everything works as expected.

[flocke]

That most likely has to do with Androids new storage permissions. They disallow direct access (e.g. when entering a path directly) and want you yo go through their storage access framework. This is the major point I want to address in the next major release. But I don't really have time to work on andOTP currently, so it will take a while...

[manuth]

I feel you - I'm having a stressful time lately, too - I'll go see whether I can drop a PR sometime.

Thanks for your rapid answer :D

[ptruman]

I'm just playing with AndOTP today (first time, nice app - thx!) - and I'm seeing this also.
However, I'm also finding when using google drive that when I backup, it saves a new copy of the file with the same filename - it doesn't overwrite the previous one? GDrive does it's own versioning so not sure what's happening here

[flocke]

Implemented persistent storage access in 356815d7e76bca3c63b5c6572162d46a293cd87b. You will need to select the backup folder again in the settings after the next update to get the persistent permissions.

[ptruman]

Awesome, thanks :)