hello, EGHDK

how can I help you today?

I have a user indicating that my file eraser app bricked his phone. Is this possible? He is saying that his galaxy S4 has encryption turned on, after he turned on my app and ran it, then after a little while he rebooted, and then said that the device wont boot.

um

unless it uses root or something, and the user removed some critical file, I fail to see how your app could brick the phone

there should be nothing on external storage that would prevent a device from booting

and that's all you have access to by default

I have permission to "WRITE_EXTERNAL_STORAGE"

but you're saying that anything that the devices needs to boot would be on "internal" storage?

more importantly, most will be on the /system partition

Which is "internal"?

neither, really

your app's portion of internal storage is getFilesDir(), getCacheDir(), etc.

Hmm... I'm using getDir()

getFilesDir(), getCacheDir(), etc. all route to getDir() AFAIK

Either way though. Without root, I can't touch the system directory (or is it a partition)?

/system is a directory, mounted on a partition

And thats what would only be the realistic thing that could mess up a phone (messing with /system)?

and, yes, without superuser privileges (a.k.a., root), you cannot write there

it is the primary area of where modifications could brick a phone

Okay, that's all I need. I just want to be able to give the user an answer.

now, there are thousands of Android devices

and I can't rule out the possibility that some device somewhere depends upon a file that could be deleted by your app even without root

IMHO, that's a bug on the device manufacturer's part

but, this is a reason why I don't write apps that mess with arbitrary data :-(

Yep. Makes sense.

Is my application data on "external" storage though?

if you mean getDir(), then no

The user thinks that my application created too much data, and then couldn't boot up.

running out of disk space could interfere with a boot, I suppose

internal and external storage are on the same partition (the /data partition)

and so from a disk space standpoint, both pull from the same place

gotcha. I don't really understand that, but that may be my lack of knowledge of how a partition works.

what OS are you using for your developer PC? Windows?

I don't get how internal and external could be on the same /data dir?

pc

"pc" is not an OS

sorry

windows or linux

well, if you using Linux, you really should know what partitions are

with respect to Windows, for the purposes of this conversation, a partition roughly equals a drive letter

or, more accurately, a drive letter points to a partition

in Linux, a partition mounts to a directory (e.g., /data)

Well, I know what a partition is, but I didn't know that you can have two drives (external and internal storage) make up one partition.

internal and external storage are separate directories inside that root /data directory

internal and external storage are not "drives"

Yeah, I've mounted stuff via cmd line before in linux

oh.

Okay, that makes more sense.

and there are other subdirectories of /data that are not part of either internal or external storage

Blowing my mind here Mark.

Hahah. Data and data in android is scary.

I guess I can look into that later though. In a nutshell... an application shouldn't have permission to mess with a devices boot up process.

a device should be robust enough to handle anything you could affect

out-of-disk-space is the one scenario where I could see you affecting something that broke the boot

though even then the device should be able to wipe out apps' getCacheDir() and getExternalCacheDir() to get enough room

if you are writing a file manager, though, it would behoove you to ensure that you don't consume all disk space

Thanks.

That's all for me. Take care. Enjoy the nice(r) weather!

thanks!