Android Question What is a safe location to share a file from?

[JohnC]

I am developing an app that will create a file that needs to be accessible by other apps on the user's device.

Using the intellisense of B4A, it shows these two directory locations:

File.DirDefaultExternal
File.DirRootExternal

If I save my app's generated file into any of the "Internal" locations, then obviously other apps will not be able to access it due to the sandboxing/security of android.

I know that most (if not all) Samsung devices using come with an internal "SDcard" location. And if you insert a removable sd card (into phones that have an SD memory slot), that location is called "extSdCard".

So, I obviously don't want my app to attempt or assume the user has a physical sd memory card inserted into their phone. But, I also don't want to assume that the users device has even an "SDcard" location, or can I assume that?

Basically, I wanted to know what location can I have my app save a file into that other apps can access and can count on that location existing on the users device no matter what device they have?

 

[NJDude]

The answer is: File.DirRootExternal

 

[JohnC]

No drum roll before the answer?

Thanks!

 

[Erel]

You can also use RuntimePermissions.GetSafeDirDefaultExternal. It returns the same path as File.DirDefaultExternal but it doesn't require the WRITE_EXTERNAL_STORAGE permission (on Android 4.4+) which is considered a "dangerous" permission. This is important if you want to switch to using runtime permissions at some point.

 

[Erel]

If you store this common file in File.DirRootExternal, anyone can read its contents.

This is also true for File.DirDefaultExternal or any other folder other than File.DirInternal / File.DirInternalCache.

 

[JohnC]

For my particular application, it needs to be visible by another 3rd party app that I am doing an Intent/Share with, so I can't encrypt it.

 

[KMatle]

it needs to be visible

So this is the answer. Either it must be "safe" OR it is visible & not encrypted...

 

[JohnC]

Sorry for the confusion, when I said "safe", I meant to convey I was looking for a "reliable" location that I could store the file and "safe" from any headaches of my app throwing errors because the location might not exist on a user's device. Thus, I was looking for something that was "safe" for me as a programmer to use, but didn't mean "safe" in the security sense.

 

[JohnC]

Since I'm using an Intent, the user has the ability to choose the app from an assortment of apps that can receive this file, so that won't be very practical.