Update Dockerfile with Android SDK

[oxr463]

See: https://github.com/mindrunner/docker-android-sdk

[oxr463]

See also: #48 (comment)

[imlk0]

@oxr463

Now we should be able to compile directly to the arm-linux-androideabi target.

Since we have already specified the linker name in .cargo/config.toml:

[target.arm-linux-androideabi]
linker = "armv7a-linux-androideabi21-clang"

[target.aarch64-linux-android]
linker = "aarch64-linux-android21-clang"

Just add <path-to-ndk-dir>/toolchains/llvm/prebuilt/linux-x86_64/bin/ into PATH, before you start compiling.

Then, install new rust target:

rustup target add arm-linux-androideabi

Start building with:

CARGO_BUILD_TARGET=arm-linux-androideabi cargo make build

It should work

[oxr463]

Maybe you can verify why this is happening, but I ran into this issue:

docker-compose run proot-rs-sdk /bin/sh
/usr/src/proot-rs # CARGO_BUILD_TARGET=arm-linux-androideabi cargo make build
info: syncing channel updates for 'nightly-2021-03-24-x86_64-unknown-linux-musl'
info: latest update on 2021-03-24, rust version 1.53.0-nightly (673d0db5e 2021-03-23)
info: downloading component 'cargo'
info: downloading component 'clippy'
info: downloading component 'rust-docs'
info: downloading component 'rust-std'
info: downloading component 'rustc'
info: downloading component 'rustfmt'
info: installing component 'cargo'
info: using up to 500.0 MiB of RAM to unpack components
info: installing component 'clippy'
info: installing component 'rust-docs'
info: installing component 'rust-std'
info: installing component 'rustc'
info: installing component 'rustfmt'
[cargo-make] INFO - cargo make 0.35.0
[cargo-make] INFO - Build File: Makefile.toml
[cargo-make] INFO - Task: build
[cargo-make] INFO - Profile: development
[cargo-make] INFO - Running Task: legacy-migration
[cargo-make] INFO - Running Task: build-loader
  Downloaded rlibc v1.0.0
  Downloaded 1 crate (7.0 KB) in 0.20s
   Compiling rlibc v1.0.0
   Compiling sc v0.2.4 (https://github.com/KB5201314/syscall.rs.git?rev=cf49872#cf498721)
error[E0463]: can't find crate for `core`
  |
  = note: the `arm-linux-androideabi` target may not be installed

error[E0463]: can't find crate for `core`
  |
  = note: the `arm-linux-androideabi` target may not be installed

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: could not compile `rlibc`

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed
[cargo-make] ERROR - Error while executing command, exit code: 101
[cargo-make] WARN - Build Failed.

The weird part is that I re-ran this command:

rustup target add arm-linux-androideabi
info: downloading component 'rust-std' for 'arm-linux-androideabi'
info: installing component 'rust-std' for 'arm-linux-androideabi'
info: using up to 500.0 MiB of RAM to unpack components

And then it successfully built for me:

CARGO_BUILD_TARGET=arm-linux-androideabi cargo make build
[cargo-make] INFO - cargo make 0.35.0
[cargo-make] INFO - Build File: Makefile.toml
[cargo-make] INFO - Task: build
[cargo-make] INFO - Profile: development
[cargo-make] INFO - Running Task: legacy-migration
[cargo-make] INFO - Running Task: build-loader
   Compiling sc v0.2.4 (https://github.com/KB5201314/syscall.rs.git?rev=cf49872#cf498721)
   Compiling rlibc v1.0.0
   Compiling loader-shim v0.1.0 (/usr/src/proot-rs/loader-shim)
    Finished dev [unoptimized + debuginfo] target(s) in 0.84s
[cargo-make] INFO - Running Task: copy-loader
[cargo-make] INFO - Running Task: build
   Compiling libc v0.2.90
   Compiling memchr v2.3.4
   Compiling bitflags v1.2.1
   Compiling log v0.4.14
   Compiling cfg-if v1.0.0
   Compiling unicode-width v0.1.8
   Compiling regex-syntax v0.6.23
   Compiling vec_map v0.8.2
   Compiling sc v0.2.4 (https://github.com/KB5201314/syscall.rs.git?rev=cf49872#cf498721)
   Compiling strsim v0.8.0
   Compiling ansi_term v0.11.0
   Compiling humantime v2.1.0
   Compiling termcolor v1.1.2
   Compiling byteorder v1.4.3
   Compiling lazy_static v1.4.0
   Compiling textwrap v0.11.0
   Compiling loader-shim v0.1.0 (/usr/src/proot-rs/loader-shim)
   Compiling aho-corasick v0.7.15
   Compiling regex v1.4.5
   Compiling atty v0.2.14
   Compiling nix v0.20.0
   Compiling clap v2.33.3
   Compiling env_logger v0.8.3
   Compiling proot-rs v0.1.0 (/usr/src/proot-rs/proot-rs)
warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
 --> proot-rs/src/main.rs:3:12
  |
3 | #![feature(specialization)]
  |            ^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
  = help: consider using `min_specialization` instead, which is more stable and complete

warning: unused import: `crate::errors::*`
 --> proot-rs/src/kernel/standard/uname.rs:1:5
  |
1 | use crate::errors::*;
  |     ^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: associated function is never used: `set_glue_type`
   --> proot-rs/src/filesystem/fs.rs:200:12
    |
200 |     pub fn set_glue_type(&mut self, mode: Mode) {
    |            ^^^^^^^^^^^^^
    |
    = note: `#[warn(dead_code)]` on by default

warning: constant is never used: `ET_REL`
  --> proot-rs/src/kernel/execve/binfmt/elf.rs:14:1
   |
14 | const ET_REL: u16 = 1;
   | ^^^^^^^^^^^^^^^^^^^^^^

warning: constant is never used: `ET_CORE`
  --> proot-rs/src/kernel/execve/binfmt/elf.rs:17:1
   |
17 | const ET_CORE: u16 = 4;
   | ^^^^^^^^^^^^^^^^^^^^^^^

warning: constant is never used: `PT_DYNAMIC`
  --> proot-rs/src/kernel/execve/binfmt/elf.rs:19:1
   |
19 | pub const PT_DYNAMIC: u32 = 2;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: struct is never constructed: `DynamicEntry`
  --> proot-rs/src/kernel/execve/binfmt/elf.rs:28:12
   |
28 | pub struct DynamicEntry<TSigned, TUnsigned> {
   |            ^^^^^^^^^^^^

warning: enum is never used: `DynamicType`
  --> proot-rs/src/kernel/execve/binfmt/elf.rs:33:10
   |
33 | pub enum DynamicType {
   |          ^^^^^^^^^^^

warning: 8 warnings emitted

    Finished dev [unoptimized + debuginfo] target(s) in 9.14s
proot-rs:       /usr/src/proot-rs/target/arm-linux-androideabi/debug/proot-rs
loader-shim:    /usr/src/proot-rs/target/arm-linux-androideabi/debug/loader-shim
[cargo-make] INFO - Build Done in 10.18 seconds.

[imlk0]

I don't see any problem with this.

On your first build, the error message reported is:

error[E0463]: can't find crate for `core`
  |
  = note: the `arm-linux-androideabi` target may not be installed

error[E0463]: can't find crate for `core`
  |
  = note: the `arm-linux-androideabi` target may not be installed

This means that you may not have the arm-linux-androideabi target installed. By running "rustup target add arm-linux-androideabi", it is installed in your environment. So when you build again it will succeed

[oxr463]

I don't see any problem with this.

On your first build, the error message reported is:

error[E0463]: can't find crate for `core`
  |
  = note: the `arm-linux-androideabi` ta需要rget may not be installed

error[E0463]: can't find crate for `core`
  |
  = note: the `arm-linux-androideabi` target may not be installed

This means that you may not have the arm-linux-androideabi target installed. By running "rustup target add arm-linux-androideabi", it is installed in your environment. So when you build again it will succeed

But the Dockerfile already added it? So I basically need to do it twice.

[imlk0]

Oh, I see, I know the reasons.

To explain this, I would like to first introduce that rust allows multiple toolchains to exist in the system. and this can be checked with rustup show:

/usr/src/proot-rs # rustup show
Default host: x86_64-unknown-linux-musl
rustup home:  /root/.rustup

installed toolchains
--------------------

stable-x86_64-unknown-linux-musl (default)
nightly-2021-03-24-x86_64-unknown-linux-musl

active toolchain
----------------

nightly-2021-03-24-x86_64-unknown-linux-musl (overridden by '/usr/src/proot-rs/rust-toolchain')
rustc 1.53.0-nightly (673d0db5e 2021-03-23)

By default the toolchain to be used is the stable version. But if there is a file named rust-toolchain in the current directory, it will be overridden to use the specified toolchain version. In our project, it's version is nightly-2021-03-24.

Here is a part of the Dockerfile:

RUN rustup-init -y && \
    rustup toolchain install stable && \
    rustup target add arm-linux-androideabi && \
    cargo +stable install --force cargo-make

WORKDIR /usr/src/proot-rs
COPY . /usr/src/proot-rs

CMD ["cargo", "make", "build"]

Here, the line

rustup target add arm-linux-androideabi

comes before

COPY . /usr/src/proot-rs

This means that we are installing a new target arm-linux-androideabi for the default toolchain (stable version).

But our project is actually using the nightly-2021-03-24 toolchain, for which we have not yet installed the target arm-linux-androideabi.

[imlk0]

I have added a patch ffdec87