FYI: How to reliably identify an Android Tablet microSD Card

[Bob Sneidar]

Interesting approach. Of course, the downside is that if anything changes, the method becomes ineffective for that new device or for all andriods if the change is fundamental enough. 

Bob S


> On Dec 19, 2018, at 03:37 , Peter Reid via use-livecode <use-livecode at lists.runrev.com> wrote:
> 
> FYI
> 
> I've managed to put together some code that reliably locates the microSD card in 4 very different Android-based tablets. The approach involves 3 different methods:
> 
> 1. Search for a known folder on the SD card starting in the standard "/mnt" folder using a breadth-first search strategy.
> 
> 2. Search for a known folder on the SD card starting in the less standard "/storage" folder using a breadth-first search strategy.
> 
> 3. Search for a known folder using full paths that are used by specific manufacturers. These look as though they should be located by method 1. (they are all paths from "/mnt") but sometimes fail 1. however they work if the full path is specified!
> 
> Here's my code for "findSDcard"...
> 
> ----------------
> 
> on findSDcard
>   constant \
>      cSDcardRoot1 = "/mnt/ext_sdcard/Android/data/com.myorg.myapp/files", \
>      cSDcardRoot2 = "/mnt/sdcard2/Android/data/com.myorg.myapp/files", \
>      cSDcardRoot3 = "/mnt/m_external_sd/Android/data/com.myorg.myapp/files", \
>      cSDcardRoot4 = "/mnt/sdcard/Android/data/com.myorg.myapp/files", \
>      cSDcardRoot5 = "/mnt/extSdCard/Android/data/com.myorg.myapp/files", \
>      cSDcardRoot6 = "/mnt/external_sd/Android/data/com.myorg.myapp/files", \
>      cSDcardRoot7 = "/mnt/SDCard/Android/data/com.myorg.myapp/files"
> 
>    global gDataPath -- /myapp-data
>    global gSDcard -- path to app's data folder
> 
>   set wholeMatches to true
>   put empty into gSDcard
>   put (char 2 to -1 of gDataPath) into tTargetFolderName
>   if the platform is "android" then
>      put "/mnt" into tDeviceRoot
>      if there is a folder tDeviceRoot then
>         -- search in standard /mnt folders:
>         put empty into tFoundPath
>         folderExists tTargetFolderName, tDeviceRoot, tFoundPath
>         if tFoundPath is not empty then
>            put tFoundPath into gSDcard
>         end if
>      end if
>      if gSDcard is empty then
>         -- try non-standard /storage folders:
>         if there is a folder "/storage" then
>            -- search in non-standard /storage folders:
>            put "/storage" into tDeviceRoot
>            put empty into tFoundPath
>            folderExists tTargetFolderName, tDeviceRoot, tFoundPath
>            if tFoundPath is not empty then
>               put tFoundPath into gSDcard 
>            end if
>         end if
>      end if
>      if gSDcard is empty then
>         -- try bespoke SD locations:
>         if there is a folder cSDcardRoot1 then
>            put cSDcardRoot1 into gSDcard    -- Huawei
>         else if there is a folder cSDcardRoot2 then
>            put cSDcardRoot2 into gSDcard    -- Amazon
>         else if there is a folder cSDcardRoot3 then
>            put cSDcardRoot3 into gSDcard    -- Lenovo
>         else if there is a folder cSDcardRoot4 then
>            put cSDcardRoot4 into gSDcard    -- Fusion
>         else if there is a folder cSDcardRoot5 then
>            put cSDcardRoot5 into gSDcard    -- ??
>         else if there is a folder cSDcardRoot6 then
>            put cSDcardRoot6 into gSDcard    -- ??
>         else if there is a folder cSDcardRoot7 then
>            put cSDcardRoot7 into gSDcard    -- Hudl?
>         end if
>      end if
>   end if
> end findSDcard
> 
> on folderExists pFolderName, pRootPath, @pFoundPath
>   constant cNoDotsRegex = "^\..*"
> 
>   -- breadth-first search for a given folder
>   put empty into pPath
>   if there is a folder pRootPath then
>      put empty into tSubFolders
>      put folders(pRootPath) into tFolderList
>      filter lines of tFolderList without regex cNoDotsRegex
>      repeat for each line tFolder in tFolderList
>         if tFolder = pFolderName then
>            -- found it:
>            put pRootPath into pFoundPath
>            exit folderExists
>         else
>            -- add sub-folder to list for checking:
>            put pRootPath & "/" & tFolder & return after tSubFolders
>         end if
>      end repeat
>      if tSubFolders is empty then
>         exit folderExists
>      end if
>      repeat for each line tSubFolder in tSubFolders
>         folderExists pFolderName, tSubFolder, pFoundPath
>         if pFoundPath is not empty then
>            exit folderExists
>         end if
>      end repeat
>   end if
> end folderExists
> 
> ----------------
> 
> Note that the above was necessary because specialFolderPath("external documents") doesn't work reliably across the 4 Android-based tablets I'm trying to support.
> 
> If anyone has a more elegant or succinct method, please let me know.  In the meantime you're welcome to use the above code.
> 
> Peter
> --
> Peter Reid
> Loughborough, UK
> 
>> On 28 Nov 2018, at 11:49am, Peter Reid <preid at reidit.co.uk> wrote:
>> 
>> I've got an app running on an Android 8.1 7in tablet which uses a microSD card for its RW data storage. I've tried using:
>> 
>> 	specialFolderPath("external documents")
>> 
>> which the docs describe as follows:
>> 
>> 	• "external documents": The folder on the primary shared/external storage device where application-specific data can be placed
>> but this doesn't point to the microSD.
>> 
>> Instead I'm having to try to pause the app and then search around for the microSD.  So far I've found 7 different locations for the microSD, depending on the model of tablet:
>> 
>> 	1. /mnt/ext_sdcard/Android/data/com.reidit.myapp/files
>> 
>> 	2. /mnt/sdcard2/Android/data/com.reidit.myapp/files
>> 
>> 	3. /mnt/m_external_sd/Android/data/com.reidit.myapp/files
>> 
>> 	4. /mnt/sdcard/Android/data/com.reidit.myapp/files
>> 
>> 	5. /mnt/extSdCard/Android/data/com.reidit.myapp/files
>> 
>> 	6. /mnt/external_sd/Android/data/com.reidit.myapp/files
>> 
>> 	7. /mnt/SDCard/Android/data/com.reidit.myapp/files
>> 
>> where the ../files folder is located in the microSD filing system as follows:
>> 
>> 	/Android
>> 		/data
>> 			/com.reidit.myapp
>> 				/files
>> 
>> Whenever I try to install my app on a different Android tablet, I have to go hunting for the exact filing system for the 1st part of the microSD:
>> 
>> 	/mnt/<unknown>/
>> 
>> The tail of /Android/data/com.reidit.myapp/files seems to be consistent. It seems that the only variable is the <unknown> part.
>> 
>> However, I have 2 tablets (Android 5.1 and Android 8.1) where I haven't been able to locate the microSD card at all!
>> 
>> Any suggestions about how to reliably locate the microSD card in an Android tablet?
>> 
>> Peter
>> --
>> Peter Reid
>> Loughborough, UK
>> 
> 
> 
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