Avoid parsing global or image-specific args

Among other things.

Dockerfile

@@ -1,3 +1,19 @@
+ARG DOCKER_VERSION="latest"
+FROM docker:${DOCKER_VERSION} AS test
+
+# Install APK deps
+RUN apk add --no-cache bash
+
+# Install dond-shim
+ARG DOCKER_PATH="/usr/local/bin/docker"
+RUN mv -f "${DOCKER_PATH}" "${DOCKER_PATH}.orig"
+COPY docker "${DOCKER_PATH}"
+
+# Create fixtures
+RUN mkdir -p /test && \
+  echo test | tee /test/only-inside-container
+
+# Set default stage
 FROM felipecrs/fixdockergid:latest
 
 USER root
@@ -7,6 +23,3 @@ RUN mv -f "${DOCKER_PATH}" "${DOCKER_PATH}.orig"
 COPY docker "${DOCKER_PATH}"
 
 USER rootless
-
-# Create fixtures
-RUN echo test | tee /home/rootless/only-inside-container

docker

@@ -2,6 +2,10 @@
 
 set -euo pipefail
 
+if [[ "${DOND_SHIM_DEBUG:-false}" == true ]]; then
+  set -x
+fi
+
 function get_container_id() {
   local cpuset_output
   cpuset_output=$(head -1 /proc/self/cpuset)
@@ -74,14 +78,107 @@ function fix_volume_arg() {
   volume_arg="${source}:${destination}"
 }
 
+function get_docker_options_with_value() {
+  local -n target_array="${1}"
+  shift 1
+  local command=("${@}")
+
+  local help_output
+  help_output="$(docker.orig "${command[@]}" --help)"
+
+  readarray -t help_lines <<<"${help_output}"
+  target_array=()
+  for line in "${help_lines[@]}"; do
+    # second group is the short option (optional)
+    # third group is the long option
+    if [[ "${line}" =~ ^[[:space:]]+((-[a-zA-Z]),[[:space:]])?(--[a-z0-9-]+)[[:space:]][a-z]+[[:space:]]+.*$ ]]; then
+      if [[ -n "${BASH_REMATCH[2]}" ]]; then
+        target_array+=("${BASH_REMATCH[2]}")
+      fi
+      target_array+=("${BASH_REMATCH[3]}")
+    fi
+  done
+}
+
+options_with_value=()
+get_docker_options_with_value options_with_value
+
 original_args=("$@")
-fixed_args=()
 
-# TODO: only piggyback on docker run, container run, create and container create
+skip_next=false
+parsing="global"
+global_args=()
+found_first_global_positional=false
+command_args=()
+image_args=()
+for i in "${!original_args[@]}"; do
+  arg="${original_args[${i}]}"
+
+  if [[ "${parsing}" == "global" ]]; then
+    global_args+=("${arg}")
+
+    if [[ "${skip_next}" == true ]]; then
+      skip_next=false
+      continue
+    fi
+
+    if [[ "${arg}" == "-"* ]]; then
+      if [[ "${found_first_global_positional}" == false ]]; then
+        for option_with_value in "${options_with_value[@]}"; do
+          if [[ "${arg}" == "${option_with_value}" ]]; then
+            skip_next=true
+            continue
+          fi
+        done
+      fi
+      continue
+    fi
+
+    if [[ "${arg}" == "run" || "${arg}" == "create" ]]; then
+      options_with_value=()
+      get_docker_options_with_value options_with_value "${arg}"
+      parsing="command"
+    elif [[ "${arg}" == "container" ]]; then
+      found_first_global_positional=true
+      true
+    else
+      # Skip if command is not run, create, container run, or container create
+      if [[ "${DOND_SHIM_PRINT_COMMAND:-false}" == true ]]; then
+        echo docker.orig "${original_args[@]}"
+        exit 0
+      else
+        exec docker.orig "${original_args[@]}"
+      fi
+    fi
+  elif [[ "${parsing}" == "command" ]]; then
+    command_args+=("${arg}")
+
+    if [[ "${skip_next}" == true ]]; then
+      skip_next=false
+      continue
+    fi
+
+    if [[ "${arg}" == "-"* ]]; then
+      for option_with_value in "${options_with_value[@]}"; do
+        if [[ "${arg}" == "${option_with_value}" ]]; then
+          skip_next=true
+          continue
+        fi
+      done
+      continue
+    fi
+
+    # If this is reached, then the first positional argument has been found
+    parsing="image"
+  elif [[ "${parsing}" == "image" ]]; then
+    image_args+=("${arg}")
+  fi
+done
 
+fixed_args=()
 extra_args=()
 fix_next_arg=false
-for arg in "${original_args[@]}"; do
+for arg in "${command_args[@]}"; do
   if [[ "${fix_next_arg}" == true ]]; then
     fix_next_arg=false
     volume_arg="${arg}"
@@ -100,4 +197,10 @@ for arg in "${original_args[@]}"; do
   extra_args=()
 done
 
-exec docker.orig "${fixed_args[@]}"
+final_command=(docker.orig "${global_args[@]}" "${fixed_args[@]}" "${image_args[@]}")
+
+if [[ "${DOND_SHIM_PRINT_COMMAND:-false}" == true ]]; then
+  echo "${final_command[@]}"
+else
+  exec "${final_command[@]}"
+fi

test.sh

@@ -1,25 +1,78 @@
 #!/bin/bash
 
-set -euxo pipefail
+set -euo pipefail
 
-image_id="$(docker build --quiet .)"
+if [[ "${DEBUG:-false}" == true ]]; then
+  set -x
+  export DOND_SHIM_DEBUG=true
+fi
 
-# shellcheck disable=SC2312
-docker_args=(docker run --rm --user "$(id -u):$(id -g)" --volume /var/run/docker.sock:/var/run/docker.sock)
+# Set docker versions from args or use defaults
+if [[ $# -eq 0 ]]; then
+  docker_versions=("18.09" "19.03" "20.10" "23" "24" latest)
+else
+  docker_versions=("$@")
+fi
 
-# Check if docker on docker is working
-"${docker_args[@]}" "${image_id}" docker version >/dev/null
+for docker_version in "${docker_versions[@]}"; do
+  echo "Testing with docker version: ${docker_version}"
 
-# Check if mounting an volume from the container gets fixed
-"${docker_args[@]}" "${image_id}" docker run --rm --volume /home/rootless/only-inside-container:/only-inside-container ubuntu:latest grep "^test$" /only-inside-container >/dev/null
-"${docker_args[@]}" "${image_id}" docker run --rm --volume=/home/rootless/only-inside-container:/only-inside-container ubuntu:latest grep "^test$" /only-inside-container >/dev/null
+  image_id="$(docker build --target test --build-arg "DOCKER_VERSION=${docker_version}" --quiet .)"
 
-# Check if mounting a volume which is already a volume gets fixed
-"${docker_args[@]}" --volume "${PWD}:/wd" "${image_id}" docker run --rm --volume /wd:/wd ubuntu:latest grep "^test$" /wd/testfile >/dev/null
+  # shellcheck disable=SC2312
+  docker_args=(docker run --rm --env DOND_SHIM_DEBUG --entrypoint= --volume /var/run/docker.sock:/var/run/docker.sock)
 
-# Same as above but for a file within the volume
-"${docker_args[@]}" --volume "${PWD}:/wd" "${image_id}" docker run --rm --volume /wd/testfile:/wd/testfile ubuntu:latest grep "^test$" /wd/testfile >/dev/null
+  echo "Do not change global options or after the image"
+  "${docker_args[@]}" --env DOND_SHIM_PRINT_COMMAND=true --volume "${PWD}:/wd" "${image_id}" \
+    docker --host test run --volume /wd:/wd alpine --volume /wd:/wd |
+    grep --quiet "^docker.orig --host test run --volume ${PWD}:/wd alpine --volume /wd:/wd$"
 
-# Volumes inside volumes
-"${docker_args[@]}" --volume "${PWD}/testfile:/home/rootless/testfile" "${image_id}" docker run --rm --volume /home/rootless:/wd ubuntu:latest grep "^test$" /wd/testfile >/dev/null
-"${docker_args[@]}" --volume "${PWD}/testfile:/home/rootless/testfile" --volume "${PWD}/testfile:/home/rootless/testfile2" "${image_id}" docker run --rm --volume /home/rootless:/wd ubuntu:latest bash -c 'grep "^test$" /wd/testfile && grep "^test$" /wd/testfile2 && grep "^test$" /wd/only-inside-container' >/dev/null
+  echo "Same but for container run"
+  "${docker_args[@]}" --env DOND_SHIM_PRINT_COMMAND=true --volume "${PWD}:/wd" "${image_id}" \
+    docker --host test container run --volume /wd:/wd alpine --volume /wd:/wd |
+    grep --quiet "^docker.orig --host test container run --volume ${PWD}:/wd alpine --volume /wd:/wd$"
+
+  echo "Same but for create"
+  "${docker_args[@]}" --env DOND_SHIM_PRINT_COMMAND=true --volume "${PWD}:/wd" "${image_id}" \
+    docker --host test create --volume /wd:/wd alpine --volume /wd:/wd |
+    grep --quiet "^docker.orig --host test create --volume ${PWD}:/wd alpine --volume /wd:/wd$"
+
+  echo "Same but container create"
+  "${docker_args[@]}" --env DOND_SHIM_PRINT_COMMAND=true --volume "${PWD}:/wd" "${image_id}" \
+    docker --host test container create --volume /wd:/wd alpine --volume /wd:/wd |
+    grep --quiet "^docker.orig --host test container create --volume ${PWD}:/wd alpine --volume /wd:/wd$"
+
+  echo "Do not do anything for other commands"
+  "${docker_args[@]}" --env DOND_SHIM_PRINT_COMMAND=true --volume "${PWD}:/wd" "${image_id}" \
+    docker --host test whatever --volume /wd:/wd alpine --volume /wd:/wd |
+    grep --quiet "^docker.orig --host test whatever --volume /wd:/wd alpine --volume /wd:/wd$"
+
+  echo "Check if docker on docker is working"
+  "${docker_args[@]}" "${image_id}" \
+    docker version >/dev/null
+
+  echo "Check if mounting an volume from the container gets fixed"
+  "${docker_args[@]}" "${image_id}" \
+    docker run --rm --volume /test/only-inside-container:/only-inside-container ubuntu:latest grep "^test$" /only-inside-container >/dev/null
+
+  echo "Same but with equals sign"
+  "${docker_args[@]}" "${image_id}" \
+    docker run --rm --volume=/test/only-inside-container:/only-inside-container ubuntu:latest grep "^test$" /only-inside-container >/dev/null
+
+  echo "Check if mounting a volume which is already a volume gets fixed"
+  "${docker_args[@]}" --volume "${PWD}:/wd" "${image_id}" \
+    docker run --rm --volume /wd:/wd ubuntu:latest grep "^test$" /wd/testfile >/dev/null
+
+  echo "Same as above but for a file within the volume"
+  "${docker_args[@]}" --volume "${PWD}:/wd" "${image_id}" \
+    docker run --rm --volume /wd/testfile:/wd/testfile ubuntu:latest grep "^test$" /wd/testfile >/dev/null
+
+  echo "Check if mounting a volume which contains another volume adds all proper volumes"
+  "${docker_args[@]}" --volume "${PWD}/testfile:/test/testfile" "${image_id}" \
+    docker run --rm --volume /test:/wd ubuntu:latest grep "^test$" /wd/testfile >/dev/null
+
+  echo "Same as above but for multiple files under different volumes"
+  "${docker_args[@]}" --volume "${PWD}/testfile:/test/testfile" --volume "${PWD}/testfile:/test/testfile2" "${image_id}" \
+    docker run --rm --volume /test:/wd ubuntu:latest bash -c 'grep "^test$" /wd/testfile && grep "^test$" /wd/testfile2 && grep "^test$" /wd/only-inside-container' >/dev/null
+
+done