how to enable Android apps to browse user mount points in /mnt

Question

I want to access and work on my remote documents (such as .docx, .xlsx, etc... and pdfs) from within my apps. For this, I have created a cifs mount point from a network sdcard (NTFS v3.1) to my android device in directory /mnt/routersd ; the problem is that some apps such as WPS Office or Adobe Reader don't offer directory list with access to root directories (Ofcourse, the device is rooted). My question is that how these apps can be enabled to explore root directory list such as /mnt/routersd in order for me to open my remote office documents and pdfs through those apps.

I want my mountpoint to be shown in WPS Office directory listing.

Or, to be shown in Adobe Reader directory explorer.

As you see, the pictures in the mountpoint is displayed by QuickPic.

Also, X-plore file explorer can explorer the mountpoint and do copy/delete operations in there.

So, how can I open my remote docs (/mnt/routersd) from within WPS Office and Adobe Reader apps?

Answer 1

Through my research, I couldn't find a way to create a symbolic link in '/sdcard' (my android internal storage) from /mnt/routersd (mountpoint to //192.168.x.x/sdcard); as filesystem for /sdcard in android doesn't support symbolic links.

I also tried busybox mount -o bind /mnt/routersd/ /sdcard/mylink but mylink couldn't be browsed by the said apps (those apps find mylink as an empty directory).

Eventually, I created the symbolic link in my external sdcard, namely sdcard1 (NTFS v3.1), successfully (recent NTFS versions support symbolic links); as follows : busybox ln -s "/mnt/routersd/" "/storage/sdcard1/mylink"

As Adobe Reader, WPS Office, and many other apps can browse into external sdcard, mylink can be visible in their dicrectory list happily. Now, I can successfully browse my remote files and work on them from within the said apps.