Android Question Rp.GetAllSafeDirsExternal returns Permission Denied

[SJQ]

Got a problem with Android 9 x86

We use two insertable storage devices, A Removable SD card is inserted that contains an extensive media library and when required staff must insert another USB and a process in the app writes specific statistics to this USB mass storage device.

previously Rp.GetAllSafeDirsExternal has worked on ARM devices for Android 6, 7 (I don’t have an Android 9 Device running on ARM to test) and Rp.GetAllSafeDirsExternal returns a directory that we can write this stats file to the removable Mass Storage. (internet or any Wi-Fi/ethernet is forbidden)

example build configuration package name: com.myb4aapp

Rp.GetAllSafeDirsExternal("") returns for example:

/storage/emulated/0/Android/data/ com.myb4aapp /files (same return as File.DirDefaultExternal)
/storage/121E-3344/Android/data/com.myb4aapp /files
/storage/BE99-160B/Android/data/com.myb4aapp/files

However, on the Android 9 x86 device when creating the stats file I get the following:

java.io.FileNotFoundException: /storage/121E-3344/Android/data/ com.myb4aapp /files/StatsExp.csv (Permission denied)

Required file permissions were granted…

Is this an Andoid 9 issue or x86 issue or both, and is there any other way around it??

 

[DonManfred]

s this an Andoid 9 issue or x86 issue or both, and is there any other way around it??

The ONLY way to access external storage (real external storage) is to use the ExternalStorage Class.

ExternalStorage - Access SD cards and USB sticks

Before we start: External storage means a real sd card or a connected mass storage USB device. This class can also be used to access the secondary storage (File.DirRootExternal). This becomes relevant with newer versions of Android that restrict direct access. It has nothing to do with runtime...

www.b4x.com

 

[SJQ]

Is it possible to automate this without requiring the user to make a drive selection?

 

[DonManfred]

No. User need to set the root path. At least one time. Once it is set you can store the reference.

 

[SJQ]

Oooh that’s not going to go down well… I’ve met our end users and its grim.

I can’t trust them to press the correct button even when its highlighted, flashing and huge… Never mind navigating an obscure default file manager to make such a complex (because to them it is) choice.

Really, I wonder if google has actually met its end users… I know professional IT people that struggle with the Android filing system never mind general users.

And on top of that its not likely to be the same USB more than once.

 

[KMatle]

Which data will be on the external drive? What about storing/retrieving the data to/from a server?

 

[SJQ]

Unfortunately Wi-Fi and Internet/Intranet are forbidden in the location.

 

[Unobtainius]

Oooh that’s not going to go down well… I’ve met our end users and its grim.

I can’t trust them to press the correct button even when its highlighted, flashing and huge… Never mind navigating an obscure default file manager to make such a complex (because to them it is) choice.

Really, I wonder if google has actually met its end users… I know professional IT people that struggle with the Android filing system never mind general users.

And on top of that its not likely to be the same USB more than once.

Some of my end users are truck drivers, so I feel you brother. Usually I just end up asking if they still have the boxes their computer came in, and if so, advise them to pack it up, take it back to the shop they got it from, and tell the sales assistant they are too dumb to use a computer

 

[Unobtainius]

If any truck drivers read my reply, well done, youre reading now! Nah, just kidding. Maybe

 

[SJQ]

I'm waiting for the fall out from this... its not just the end users but the client senior management whos technical abilities start and end at a matchbox just wont understand.

part of the problem is Googles unhelpful helpfulness, in the default file manager that opens in this process it loads the 'Recent' page first with absolutely no obvious path or indication on what to do.

Thing with this is, out of the drives connected I know what drive to use, I just can't see a way to pass this in as a parameter.

 

[SJQ]

I take it the function the user has to use returns a URI for the root of the drive?

I've found a code snippet on here to convert a file path to a URI, in the FileProvider class, doesn't work as it is though.

But there must be some way to format this to the correct requirement?

 

[Erel]

As written above you must use ExternalStorage to access a connected USB storage device and the user must choose the root folder once.
FileProvider is not related.