Overview

bindfs - https://bindfs.org/

This repo has been patched to support NDK compilation for android, since some functions are not provided by bionic which are used in src/userinfo.c. Patch is done based on a termux patch.

bindfs is a FUSE filesystem for mirroring a directory to another directory, similarly to mount --bind. The permissions of the mirrored directory can be altered in various ways.

Some things bindfs can be used for:

• Making a directory read-only.
• Making all executables non-executable.
• Sharing a directory with a list of users (or groups).
• Modifying permission bits using rules with chmod-like syntax.
• Changing the permissions with which files are created.

Non-root users can use almost all features, but most interesting use-cases need user_allow_other to be defined in /etc/fuse.conf.

Installation

Make sure FUSE 2.6.0 or above is installed (https://github.com/libfuse/libfuse).

Download a release or clone this repository.

Then compile and install as usual:

./configure
make
make install

If you want the mounts made by non-root users to be visible to other users, you may have to add the line user_allow_other to /etc/fuse.conf.

In Linux-based OSes, you may have to add your user to the fuse group.

Usage

See the bindfs --help or the man-page for instructions and examples.

OS X note

The following extra options may be useful under osxfuse:

-o local,allow_other,extended_security,noappledouble

See https://github.com/osxfuse/osxfuse/wiki/Mount-options for details.

Test suite

Bindfs comes with a (somewhat brittle and messy) test suite. The test suite has two kinds of tests: those that have to be run as root and those that have to be run as non-root. To run all of the tests, do make check both as root and as non-root.

The test suite requires Ruby 1.8.7+. If you're using RVM then you may need to use rvmsudo instead of plain sudo to run the root tests.

Vagrant test runner

There is also a set of Vagrant configs for running the test suite on a variety of systems. Run them with vagrant/test.rb (add --help for extra options).

You can destroy all bindfs Vagrant machines (but not the downloaded images) with make vagrant-clean.

Cross Compile Instructions for Android Using NDK

• bindfs requires fuse libraries for compilation. fuse compiled with NDK is used for this.

• Follow instructions for fuse but do not build it.

• Copy bindfs directory to android_ndk_cross_compile_build_automator/packages directory.

• Copy bindfs/post_build_scripts/bindfs_extractor.sh file to android_ndk_cross_compile_build_automator/$POST_BUILD_SCRIPTS_DIR/ directory.

• Add/Set fuse bindfs to $PROJECTS_TO_BUILD in android_ndk_cross_compile_build_automator.sh.

• Add/Set fusermount_extractor.sh bindfs_extractor.fs to $POST_BUILD_SCRIPTS_TO_RUN in android_ndk_cross_compile_build_automator.sh. You can skip this optionally if you do not want to create a zip of the fusermount and bindfs binaries of all the archs that are built.

• Add/Set armeabi armeabi-v7a arm64-v8a x86 x86-64 to $ARCHS_SRC_TO_BUILD in android_ndk_cross_compile_build_automator.sh or whatever ARCHS_SRC you want to build for. API_LEVEL in ARCH_SRC files must be 21 or higher otherwise compilation will fail. NDK must also be higher than r15. Check fuse/android_ndk_cross_compile_build.sh for more details.

#install dependencies
sudo apt install autoconf automake libtool

cd android_ndk_cross_compile_build_automator

#build
bash ./android_ndk_cross_compile_build_automator.sh

• android_ndk_cross_compile_build_automator will call fuse/android_ndk_cross_compile_build.sh script to build and install each ARCHS_SRC. fuse for each ARCHS_SRC will be installed at android_ndk_cross_compile_build_automator/$INSTALL_DIR/fuse/$ARCHS_SRC.

• android_ndk_cross_compile_build_automator will then call bindfs/android_ndk_cross_compile_build.sh script to build and install each ARCHS_SRC. bindfs for each ARCHS_SRC will be installed at android_ndk_cross_compile_build_automator/$INSTALL_DIR/bindfs/$ARCHS_SRC.

• android_ndk_cross_compile_build_automator/$POST_BUILD_SCRIPTS_DIR/fusermount_extractor.sh will extract fusermount binaries from android_ndk_cross_compile_build_automator/$INSTALL_DIR/fuse/$ARCHS_SRC and zip them at android_ndk_cross_compile_build_automator/$OUT_DIR/fuse/fusermount<build-info>.zip.

• android_ndk_cross_compile_build_automator/$POST_BUILD_SCRIPTS_DIR/bindfs_extractor.sh will extract bindfs binaries from android_ndk_cross_compile_build_automator/$INSTALL_DIR/bindfs/$ARCHS_SRC and zip them at android_ndk_cross_compile_build_automator/$OUT_DIR/bindfs/bindfs<build-info>.zip.

Install Instructions for Termux on Android

• Download release zip or copy the zip built from source to your device.

• Extract the binary of your device arch or abi from the zip.

#command to find device arch
uname -m

#command to find device abi
getprop ro.product.cpu.abi

• Copy the binary to /data/data/com.termux/files/usr/bin and then set correct ownership and permissions by running the following commands in a non-root shell. If you run them in a root shell, then binary will only be runnable in a root shell.

export scripts_path="/data/data/com.termux/files/usr/bin"; export termux_uid="$(id -u)"; export termux_gid="$(id -g)"; su -c chown $termux_uid:$termux_gid "$scripts_path/bindfs" && chmod 700 "$scripts_path/bindfs";

License

GNU General Public License version 2 or any later version. See the file COPYING.