Android NDK r23 build problem

bt90 · September 16, 2021, 5:23pm

You’ll have to switch compiler and linker.

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

Catfriend1 · September 17, 2021, 2:03pm

Ok, I got this output. Anything useful or a hint in there?

(Too big for the forum, 34 K output) → # runtime/cgoAndroid (7284624, based on r416183b) clang version 12.0.5 (https: - Pastebin.com

Catfriend1 · September 17, 2021, 2:09pm

Result:

go build -v -tags noupgrade -trimpath -ldflags -w -X github.com/syncthing/syncthing/lib/build.Version=v1.18.2 -X github.com/syncthing/syncthing/lib/build.Stamp=1629655487 -X github.com/syncthing/syncthing/lib/build.User=XXX -X github.com/syncthing/syncthing/lib/build.Host=XXX -X github.com/syncthing/syncthing/lib/build.Tags=noupgrade github.com/syncthing/syncthing/cmd/syncthing

I’ve also tried to modify “build.go” from …

args := []string{"build", "-v"}

to

args := []string{"build", "-v -x"}

but got an error:

runPrint: go build -v -x -tags noupgrade (...)
flag provided but not defined: -v -x
usage: go build [-o output] [build flags] [packages]
Run 'go help build' for details.
exit status 2

Catfriend1 · September 17, 2021, 2:13pm

Ok, understood. But I’m clueless to what exactly I have to switch and if those LD_FLAGS, EXTRA_LDFLAGS, CGO_LDFLAGS get respected in the right place if I set them.

AudriusButkevicius · September 17, 2021, 2:56pm

-v and -x should be separate variables in the array, also, it might be that -v needs to be passed to the C compiler.

bt90 · September 17, 2021, 3:08pm

Might be worth to check what gomobile is using.

gomobile build -x

bt90 · September 17, 2021, 4:19pm

Looks like we only really use cgo for darwin/solaris filewatcher implementation. In theory cross-compiling should be a lot easier without cgo?

AudriusButkevicius · September 17, 2021, 5:10pm

Dns used to not work without cgo

AudriusButkevicius · September 17, 2021, 5:11pm

So whats the goal here? Build with an ndk newer than r22?

I might have a look at if it’s clear what we want to achieve.

Catfriend1 · September 17, 2021, 6:48pm

Yes, exactly. If you’ve got some time for this, I’d appreciate you looking into

AudriusButkevicius · September 17, 2021, 9:56pm

Just vanilla bumping of numbers works fine for me:

Catfriend1 · September 18, 2021, 7:11am

@AudriusButkevicius

I’ve merged your build script changes into my branch and it indeed worked. Strange, from code perspective I don’t see any significant changes, maybe it’s the NDK_VERSION value in build.gradle which causes some components to reconfigure things differently.

Thank you, we’re back into business with NDK r23 now !

P.S. I’ve also migrated to Android Studio Arctic Fox. Had the 2019.x version before on my computer.

tomasz86 · September 18, 2021, 11:00am

Do you have any idea how to proceed with command line compilation?

Under Windows,

set "CC=<full-path-to-ndk>\toolchains\llvm\prebuilt\windows-x86_64\bin\armv7a-linux-androideabi16-clang.cmd"
set "CGO_ENABLED=1"
go run build.go -goos android -no-upgrade -goarch arm zip

works with no problems with the older NDKs, but with NDK r23 I still only get

runtime/cgo
# runtime/cgo
ld: error: cannot open output file $WORK\b083\_cgo_.o: Function not implemented
clang: error: linker command failed with exit code 1 (use -v to see invocation)

.

Catfriend1 · September 18, 2021, 3:32pm

See the main branch of the fork (SyncthingNative_build.cmd) where I’ve adopted Audrius’ changes. Build works immediately using ndk r23.

ref: https://github.com/Catfriend1/syncthing-android/commit/28e84e929d37941b876b07d3310dfedf6f3dc9bd

AudriusButkevicius · September 18, 2021, 5:20pm

You can’t set CC, you need to pass it as -cc, as it tries to use cgo to build build.go, which is not what you want.

Catfriend1 · September 27, 2021, 3:00pm

I still have a problem when building under F-Droid vagrant and Debian amd64:

.../android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/clang: line 1: clang-12: command not found

apt-get install -y gcc gcc-arm-linux-gnueabi gcc-arm-linux-gnueabihf gcc-aarch64-linux-gnu

and then change the call in “build-syncthing.py” to “-cc /usr/bin/arm-linux-gnueabi-gcc”, I get a lot of include errors despite also setting the env var:

export SYSROOT=/root/work/syncthing-android-prereq/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/sysroot

I’ve read here it works on your docker image, what is the magic that CGO finds the correct gcc (or clang-12)?

Catfriend1 · September 27, 2021, 3:05pm

Very strange, I’ve tried every mix of env vars - no luck. If I do:

echo "`dirname $0`/clang-12 $@" > /root/work/syncthing-android-prereq/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/clang

the arm build starts to work magically. How can I do this “officially” without modding the Android NDK prebuilt files?

calmh · September 27, 2021, 3:11pm

IHNI, but the Dockerfile is this:

github.com

syncthing/syncthing-android/blob/main/docker/Dockerfile

FROM openjdk:11

ENV GO_VERSION 1.17.1

ARG ANDROID_SDK_VERSION=7583922
ARG ANDROID_SDK_FILENAME=commandlinetools-linux-${ANDROID_SDK_VERSION}_latest.zip

WORKDIR /opt

# Install Go
RUN wget -q https://dl.google.com/go/go${GO_VERSION}.linux-amd64.tar.gz && \
    tar -zxf go${GO_VERSION}.linux-amd64.tar.gz && \
    rm go${GO_VERSION}.linux-amd64.tar.gz
ENV GOROOT /opt/go
ENV PATH /opt/go/bin:${PATH}

# Install Android SDK manager
RUN mkdir -p /opt/android-sdk && cd /opt/android-sdk && \
    wget -q https://dl.google.com/android/repository/${ANDROID_SDK_FILENAME} && \
    unzip -q ${ANDROID_SDK_FILENAME} && \

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and then we apparently build using a python script which I assume exists in your fork as well

github.com

syncthing/syncthing-android/blob/main/syncthing/build-syncthing.py

from __future__ import print_function

import os
import os.path
import platform
import subprocess
import sys

PLATFORM_DIRS = {
    'Windows': 'windows-x86_64',
    'Linux': 'linux-x86_64',
    'Darwin': 'darwin-x86-64',
}

# The values here must correspond with those in ../docker/prebuild.sh
BUILD_TARGETS = [
    {
        'arch': 'arm',
        'goarch': 'arm',
        'jni_dir': 'armeabi',

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which appears to do some gymnastics to set cc.

Catfriend1 · September 27, 2021, 5:24pm

Correct. Somehow a debian amd64 bullseye or F-Droid vagrant box isn’t able to search for the correct utility paths. I now did a hacky way and replaced the “clang” batch of the linux ndk r23 with

`dirname $0`/clang-12 $@

and everything works fine again.

tomasz86 · November 27, 2022, 8:24pm

I’m very sorry to bump this, but I’m still struggling to get the build to work. This time I’m not setting any CC variables myself. I’m just trying to follow the steps as described in detail in https://github.com/syncthing/syncthing-android/pull/1865/files, which basically are about setting the ANDROID_HOME variable and then executing ./gradlew buildNative.

However, the build still fails with a very similar error.

> Task :syncthing:checkPython
Using python 3.10.5 from C:\Users\User\AppData\Local\Programs\Python\Python310 (python)

> Task :syncthing:buildNative
[python] python -u ./build-syncthing.py
         Building syncthing for arm
         Notice: Next generation GUI will not be built; see --with-next-gen-gui.
         runtime/cgo
         net
         golang.org/x/net/internal/socks
         vendor/golang.org/x/net/http/httpproxy
         log/syslog
         net/textproto
         github.com/lucas-clemente/quic-go/internal/utils
         crypto/x509
         golang.org/x/net/internal/socket
         github.com/syncthing/syncthing/lib/protocol
         github.com/rcrowley/go-metrics
         github.com/jackpal/gateway
         golang.org/x/net/proxy
         github.com/jackpal/go-nat-pmp
         vendor/golang.org/x/net/http/httpguts
         github.com/ccding/go-stun/stun
         golang.org/x/net/ipv4
         golang.org/x/net/ipv6
         crypto/tls
         github.com/syncthing/syncthing/lib/beacon
         github.com/syncthing/syncthing/lib/relay/protocol
         net/http/httptrace
         github.com/syncthing/syncthing/lib/tlsutil
         github.com/marten-seemann/qtls-go1-19
         net/http
         github.com/lucas-clemente/quic-go/internal/qtls
         github.com/lucas-clemente/quic-go/internal/qerr
         github.com/lucas-clemente/quic-go/internal/wire
         github.com/lucas-clemente/quic-go/logging
         github.com/lucas-clemente/quic-go/internal/handshake
         github.com/lucas-clemente/quic-go
         github.com/syncthing/syncthing/lib/dialer
         github.com/go-ldap/ldap/v3
         github.com/syncthing/syncthing/lib/osutil
         github.com/syncthing/syncthing/lib/relay/client
         github.com/syncthing/syncthing/lib/config
         github.com/AudriusButkevicius/pfilter
         github.com/syncthing/syncthing/lib/nat
         github.com/syncthing/syncthing/lib/stun
         github.com/syncthing/syncthing/lib/discover
         github.com/syncthing/syncthing/cmd/syncthing/cli
         github.com/syncthing/syncthing/lib/pmp
         github.com/syncthing/syncthing/lib/upnp
         github.com/syncthing/syncthing/lib/connections
         github.com/syncthing/syncthing/lib/ur
         github.com/syncthing/syncthing/lib/model
         github.com/syncthing/syncthing/lib/api
         github.com/syncthing/syncthing/cmd/syncthing
         # github.com/syncthing/syncthing/cmd/syncthing
         C:\Program Files\Go\pkg\tool\windows_amd64\link.exe: running R:\commandlinetools-win-9123335_latest\ndk\23.0.7599858/toolchains/llvm/prebuilt//windows-x86_64/bin/armv7a-linux-androideabi16-clang failed: exit status 1
         ld: error: cannot open output file $WORK\b001\exe\a.out: Function not implemented
         clang: error: linker command failed with exit code 1 (use -v to see invocation)

         exit status 2
         exit status 1
         Traceback (most recent call last):
           File "R:\syncthing\syncthing-android\syncthing\build-syncthing.py", line 104, in <module>
             subprocess.check_call(
           File "C:\Users\User\AppData\Local\Programs\Python\Python310\lib\subprocess.py", line 369, in check_call
             raise CalledProcessError(retcode, cmd)
         subprocess.CalledProcessError: Command '['go', 'run', 'build.go', '-goos', 'android', '-goarch', 'arm', '-cc', 'R:\\commandlinetools-win-9123335_latest\\ndk\\23.0.7599858/toolchains/llvm/prebuilt//windows-x86_64/bin/armv7a-linux-androideabi16-clang', '-pkgdir', 'R:\\syncthing\\syncthing-android\\syncthing\\gobuild\\go-packages\\arm', '-no-upgrade', 'build']' returned non-zero exit status 1.

> Task :syncthing:buildNative FAILED

FAILURE: Build failed with an exception.

I’ve tried checking both the Docker build script and build-syncthing.py, but I can’t see what is wrong with my build steps. Also, as far as I understand, when using ./gradlew buildNative, the build-syncthing.py is executed and CC is passed using -cc automatically, yet the compilation still fails, so I’m really out of ideas what can be wrong here .

If anyone can point at any specific clues or has an idea what needs to be done to get this to work, I will be extremely grateful.

For the record, I’m trying to build under Windows 10 x64.