Fix git security issue with docker build

Make the docker user id and group id match the running user's, so that
files built by the container are seen as owned by the current user. Also
set the current directory as "safe" in git so it's able to inspect the
git history.

_note_: this will successfully run in a rootless docker install, but the
created files will have random uid/guids. You'll have to sudo to delete
them or chown them. For normal docker installs there should be no
issues. See [this issue](moby/moby#41497) to
track the rootless problem on the docker side.

Author: skeet70

Dockerfile

@@ -1,14 +1,19 @@
 FROM ubuntu:focal
 
+ARG USER_ID
+ARG GROUP_ID
 ENV DEBIAN_FRONTEND noninteractive
 
-RUN apt-get update && apt-get install -y git cmake make ruby gcc python3 python3-pip
+RUN apt-get update && apt-get install -y git cmake make ruby gcc python3 python3-pip gcc-arm-none-eabi
 
 RUN pip install pyyaml
 
-RUN useradd inav
+# if either of these are already set the same as the user's machine, leave them be and ignore the error
+RUN addgroup --gid $GROUP_ID users; exit 0;
+RUN adduser --disabled-password --gecos '' --uid $USER_ID --gid $GROUP_ID user; exit 0;
 
-USER inav
+USER user
+RUN git config --global --add safe.directory /src
 
 VOLUME /src
 

build.sh

@@ -21,19 +21,29 @@ fi
 
 if [ -z "$(docker images -q inav-build)" ]; then
   echo -e "*** Building image\n"
-  docker build -t inav-build .
+  docker build -t inav-build --build-arg USER_ID="$(id -u)" --build-arg GROUP_ID="$(id -g)" .
   echo -ne "\n"
 fi
 
 if [ ! -d ./build ]; then
   echo -e "*** Creating build directory\n"
-  mkdir ./build
+  mkdir ./build && chmod 777 ./build
+fi
+
+if [ ! -d ./downloads ]; then
+  echo -e "*** Creating downloads directory\n"
+  mkdir ./downloads && chmod 777 ./downloads
+fi
+
+if [ ! -d ./tools ]; then
+  echo -e "*** Creating tools directory\n"
+  mkdir ./tools && chmod 777 ./tools
 fi
 
 echo -e "*** Building targets [$@]\n"
 docker run --rm -it -v "$(pwd)":/src inav-build $@
 
-if ls ./build/*.hex &> /dev/null; then
+if [ -z "$(ls ./build/*.hex &> /dev/null)" ]; then
   echo -e "\n*** Built targets in ./build:"
   stat -c "%n (%.19y)" ./build/*.hex
 fi