Android: disambiguating file paths

Question

In my app, users pick files. Internally, I store information about the file, which I key based on the file path. Next time that file is used, I do stuff with the stored inform

Answer 1

On newer Android versions, SD storage is available from many paths, for example:

/storage/emulated/0
/storage/emulated/legacy (root account most of the time)
/sdcard
/data/media

If you check on which device those paths are located, some are on different devices (because of fuse 'virtual' filesystem), hence getting their canonical path doesn't lead to the same file path, even though they are actually the same files.

Furthermore, it appears that on Marshmallow, things get worse and even file path under /sys (full of redirections/links) are not reported properly and getCanonicalPath() returns the original path instead of actual canonical path.

While a ls -l (or readlink) on the given file path will show the actual canonical path, the API doesn't work anymore. Unfortunately running a readlink or ls -l is very slow (average of 130ms when the shell is already running), compared to an already slow, but much faster getCanonicalPath(), it's a pity.

Conclusion, getCanonicalPath is broken and has always been broken.