Fix build for Raspberry Pi 1 B+ and Zero

.dockerignore

@@ -0,0 +1 @@
+/bin/ubxtool.*

.gitignore

@@ -11,7 +11,9 @@ testrunner
 tlecatch
 ubxtool
 ubxtool.nodeps
-ubxtool.nodeps.*
+ubxtool.static
+# - created by build-ubxtool
+/bin/ubxtool.*
 # - created by update-tles
 active.txt
 beidou.txt

Dockerfile.ubxtool → Dockerfile.ubxtool.glibc

@@ -14,6 +14,7 @@ RUN set -ex && \
     apt-get install -y \
         build-essential \
         g++ \
+        git \
         libprotobuf-dev \
         make \
         protobuf-compiler \

Dockerfile.ubxtool.static

@@ -0,0 +1,33 @@
+# See `build-ubxtool` script for cross-compilation options.
+
+# 1. GCC has issues with exception unwinding with static build of libmusl.
+# The bug is fixed for gcc-10, but alpine:3.11 has 9.2.0-r3 and alpine:3.10 has 8.3.0-r0.
+# Both are affected per test and https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91737
+#
+# 2. clang-9.0.0-r1 from alpine:3.11 generates wrong FPU instructions for Raspberry Pi 1 B+ and Zero.
+# It uses d{16..31} registers for a VFPv2 FPU and that leads to SIGILL.
+# The bug is described at https://reviews.llvm.org/D67375
+# The bug is fixed in clang-10: https://reviews.llvm.org/rGddf5e86c222c6b5226be53e1250421fe608bb4d0
+#
+# 3. clang-8.0.0-r0 from alpine:3.10 is not affected by the bug, so we use it.
+FROM alpine:3.10 AS build-env
+
+# g++ is still installed to bring C++ headers like <string>, <map>, etc.
+# See https://pkgs.alpinelinux.org/contents?file=iostream&branch=v3.10&arch=armhf
+RUN set -ex && \
+    apk add --no-cache \
+        clang \
+        g++ \
+        git \
+        make \
+        protobuf-dev \
+    && \
+    :
+
+ADD . /galmon/
+WORKDIR /galmon/
+RUN CXX=clang make ubxtool.static
+
+FROM scratch
+COPY --from=build-env /galmon/ubxtool.static /opt/ubxtool
+ENTRYPOINT ["/opt/ubxtool"]

Makefile

@@ -73,6 +73,9 @@ UBXTOOL_DEPS = navmon.pb.o ubxtool.o ubx.o bits.o ext/fmt-5.2.1/src/format.o gal
 
 ubxtool: $(UBXTOOL_DEPS)
 	$(CXX) -std=gnu++17 $^ -o $@ -L/usr/local/lib -lprotobuf -pthread
+# Static build with musl on alpine and clang
+ubxtool.static: $(UBXTOOL_DEPS)
+	$(CXX) -std=gnu++17 $^ -o $@ -L/usr/local/lib -lprotobuf -pthread -lstdc++ -static
 # Static linking of `glibc` is non-trivial, so glibc is kept dynamically linked
 ubxtool.nodeps: $(UBXTOOL_DEPS)
 	$(CXX) -std=gnu++17 $^ -o $@ -L/usr/local/lib /usr/lib/*-linux-*/libprotobuf.a -pthread -static-libgcc -static-libstdc++

build-ubxtool

@@ -3,31 +3,87 @@
 # The script relies on the following project:
 # - https://github.com/multiarch/qemu-user-static
 # - https://github.com/multiarch/ubuntu-core
+# - https://github.com/multiarch/alpine
 #
-# Another easy cross-compilation option is to use https://github.com/docker/binfmt
+# It's also probably possible to use more official {i386,amd64,arm32v6,arm32v7,arm64v8}/alpine
+# images adding qemu binary from multiarch/qemu-user-static:{arm,arm64} to them.
 #
 # Register qemu-user-static before building
 # $ docker run --rm --privileged multiarch/qemu-user-static:register --reset
 
 set -e
 
-arch=${1:-native}
-
-case "$arch" in
-    native)
-        tag=latest
-        from=ubuntu:bionic
-    ;;
-    x86|x86_64|arm64|armhf)
-        tag=${arch}
-        from=multiarch/ubuntu-core:${arch}-bionic
-    ;;
+this_mach=$(uname --machine)
+
+if [ "$this_mach" != "x86_64" ]; then
+    echo "$0: build was tested on x86_64, not on this <$this_mach>" 1>&2
+fi
+
+mach=${1:-${this_mach}}
+libc=${2:-static}
+
+case "$mach" in
+    i686)
+        alpine=x86 # official: i386/alpine
+        ubuntu=x86
+        busybox=i386
+        ;;
+    x86_64)
+        alpine=x86_64 # official: amd64/alpine
+        ubuntu=x86_64
+        busybox=amd64
+        ;;
+    armv6l)
+        # For Raspberry 1 and Zero.
+        # Tested on Raspberry 1 B+ (BCM2835 rev. 0010).
+        alpine=armhf # official: arm32v6/alpine
+        ubuntu=*
+        busybox=arm32v6
+        ;;
+    armv7l)
+        # For Raspberry 2 and 3.
+        # Tested on Raspberry 3 Model B (BCM2835 revision a02082).
+        # Tested on Raspberry 3 Model B+ (BCM2835 revision a020d3).
+        alpine=armv7 # official: arm32v7/alpine
+        ubuntu=armhf
+        busybox=arm32v7
+        ;;
+    aarch64)
+        # For Raspberry 4?
+        alpine=arm64 # official: arm64v8/alpine
+        ubuntu=arm64 # or aarch64? See https://wiki.ubuntu.com/ARM/RaspberryPi#Ubuntu_arm64.2FAArch64
+        busybox=arm64v8
+        ;;
     *)
-    echo "$0: unknown arch <$arch>, known are: (native|x86|x86_64|arm64|armhf)" 1>&2
+    echo "$0: unknown machine hardware name <$mach>, known are: {i686,x86_64,armv6l,armv7l,aarch64}" 1>&2
     exit 1
 esac
 
-sed "s,^FROM ubuntu:bionic AS,FROM ${from} AS," Dockerfile.ubxtool | docker build -f - --tag ubxtool:${tag} .
+case "$libc" in
+    static)
+        from="alpine:3.10"
+        to="multiarch/alpine:${alpine}-v3.10"
+        ;;
+    glibc)
+        if [ "$ubuntu" = "*" ]; then
+            echo "$0: unsupported combination of machine <$mach> and libc <$libc>" 1>&2
+            exit 1
+        fi
+        from="ubuntu:bionic"
+        to="multiarch/ubuntu-core:${ubuntu}-bionic"
+        ;;
+    *)
+    echo "$0: unknown libc <$libc>, known are: {static,glibc}" 1>&2
+    exit 1
+esac
+
+tag="${mach}-${libc}"
+
+sed -e "s,^FROM ${from} AS ,FROM ${to} AS ," \
+    -e "s,^FROM busybox:glibc,FROM ${busybox}/busybox:glibc," \
+    Dockerfile.ubxtool.${libc} \
+    | docker build -f - --tag ubxtool:${tag} .
+
 cntr=$(docker create ubxtool:${tag})
-docker cp ${cntr}:/opt/ubxtool ./ubxtool.nodeps.${tag}
+docker cp ${cntr}:/opt/ubxtool bin/ubxtool.${tag}
 docker rm ${cntr}

ubxtool.cc

@@ -16,6 +16,7 @@
 #include <iostream>
 #include <fstream>
 #include <string.h>
+#include <signal.h>
 #include "fmt/format.h"
 #include "fmt/printf.h"
 #include "bits.hh"