Comment by pjmlp

7 months ago

Many folks keep thinking that just because Android uses the Linux kernel, it is supposed to behave like GNU/Linux.

Likewise they will be rather surprised to insist in targeting iOS/iPadOS/watchOS as if they are UNIX clones.

9 comments

pjmlp

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bmicraft  7 months ago

Android being linux has exactly nothing to do with the fact that apps can't access resources outside their sandbox if they aren't mapped in somehow. Just like with lxc or docker containers on linux, jails on *bsd, or any other sandboxes.

  • pjmlp  7 months ago

    The only Linux thing on Android is the kernel, use anything else at your peril regarding portability between updates and OEM custom forks.

    https://developer.android.com/ndk/guides/stable_apis

    • bmicraft  7 months ago

      The only linux thing is always the kernel. Userspace isn't linux by definition on any* system. That might seem like a pedantic point to make, but I would like to point out that gnu utils aren't required to make a system "Linux", and whether you're using a drop-in replacement like uutils or go a more different route doesn't make it any less "Linux".

      Android Apps are and mostly always have been restricted to the Java virtual machine (or its modern equivalent) exactly because that makes them portable between sometimes quite different base systems from different vendors. If you insist that makes it less of a Linux system I'd like to know what you think of flatpak apps on top of immutable distros. I hope you agree that, conceptually, they're quite close actually.

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  • beeboobaa3  7 months ago

    The point is you can't use the regular filesystem syscalls on android, it has to go through a weird java layer

    • scottbez1  7 months ago

      And perhaps more to the point - you USED to be able to use normal Java file apis and syscalls outside of Java, but that functionality has been gradually whittled away (in the name of legitimate security improvement) over the years, meaning "basic" IO functionality your apps relied upon could be taken away at any point and replaced by less ergonomic Java-only APIs with less functionality.

      Fun fact: the official Dropbox Android app used to use inotify to watch for changes to the publicly writeable synced files in order to sync back to the cloud! Had to be replaced by java Storage Access Framework APIs later.

      Another fun fact is that the Android sdk came with a JNI wrapper around inotify but it buggily stored inotify handles in a static (global, within an app vm) dictionary, meaning you'd silently lose tracking if you created more than one Java file watcher object that happened to be for the same path, so I had to rewrite that JNI wrapper back in the day to avoid that global state bug.