Android Question File.MakeDir making unwritable folders

[techgreyeye]

Hi All,

I've been implementing data backup for my app and have some strange results. Has anyone seen this behaviour before?

I create a folder using File.MakeDir and try to copy a file into it. I then get the following exception :

(Exception) java.lang.Exception:  java.io.FileNotFoundException: /storage/emulated/0/Android/data/gtl.stockmate/files/out5/hh_auth.txt: open failed: ENOENT (No such file or directory)

Further examination revealed that the folder is created and the permissions look correct (using ES File Explorer), but somehow this folder is not writeable. I can't copy a file into it at all, either in my app, or ES File Explorer. The folder is somehow corrupt.

So... I implemented the following bit of code :

   Dim created As Boolean
   Dim retries As Int
   retries = 0
   created = False
   Do While Not (created)
    Try
     File.MakeDir(Main.Home_Folder, "out" & outid)
     File.Copy(Main.Home_Folder, "hh_auth.txt", Main.Home_Folder & "/out" & outid, "hh_auth.txt")
     created = True
    Catch
     Log(LastException)
     retries = retries + 1
     created = False
     If File.Exists(Main.Home_Folder, "out" & outid) Then
      File.Delete(Main.Home_Folder, "out" & outid)
     End If
    End Try
   Loop
  If retries > 0 Then
   Msgbox("Retries - " & retries, "Error")
  End If

The results of running this repeatedly are basically after a random number of retries

(16,14,8,0,0,19,10,5,0,20 in a run of ten tests), the folder is successfully created and the file copied in.

This only seems to happen when creating a folder which previously existed (it get's deleted earlier in the backup process). The retries above are for a folder which previously contained 10 files.

I re-tested using a folder which contained 70 files and had the following number of retries -
133,246,171,244,276,159,246,251,232,232

This is hinting that it's related to file allocation tables, but I know very little about filesystems so....


Has anyone had a similar issue, and can suggest what's might be going on and/or workarounds smarter then retrying lots of times?


Thanks!!​

 

[techgreyeye]

Further info -

I retested on a couple of other devices, and this is happening on both my android 5.0.2 devices (ASUS P01Z and Nexus 7) but not my Android 7 phone.

 

[buras3]

hi
try to bullied folders with runtime permission and not with makedir
https://www.b4x.com/android/forum/threads/runtime-permissions-android-6-0-permissions.67689/#content

 

[techgreyeye]

Hi buras,

The folder is within the apps default storage so doesn't need permissions. I have no general problem creating folders, just issues when I delete then immediately re-create a folder.

Thanks

 

[buras3]

hi
i have tested your code and i didn't get any message
i tested with 1 file only
but i saw this

 

[Erel]

File.MakeDir calls a standard OS API. If the folder created is corrupted then it is an OS issue.

Worth adding a Sleep(300) before the next attempt.