Soong: Add unbind option to setup_go_workspace_for_soong.sh script

The setup_go_workspace_for_soong now allows the reverse operation
of unbinding the directories of the previous operation. Also,
refactored the script to easily add more directories to bind/unbind
in the future, catch failures on running in subshell commands and
a cleaner way to find the repo top directory.

Bug: b/129407866
Test: Manually tested by running the script on binding and unbinding
the directories. Tested both darwin and linux OS.

Change-Id: I7c93230aeab819ab5747e990e95aa26077071d9e

scripts/setup_go_workspace_for_soong.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 set -e
 
-# Copyright 2017 Google Inc. All rights reserved.
+# Copyright 2019 Google Inc. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -15,23 +15,174 @@ set -e
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-#mounts the components of soong into a directory structure that Go tools and editors expect
+# Mounts the components of soong into a directory structure that Go tools
+# and editors expect.
 
-#move to the script's directory
-cd "$(dirname $0)"
-SCRIPT_PATH="$PWD"
 
-#find the root of the Repo checkout
+#####################################################################
-cd "${SCRIPT_PATH}"/../../..
+# Print the message to stderr with the prefix ERROR and abort this
-ANDROID_PATH="${PWD}"
+# script.
-OUTPUT_PATH="$(echo ${GOPATH} | sed 's/\:.*//')" #if GOPATH contains multiple paths, use the first one
+#####################################################################
-
+function log_FATAL() {
-if [ -z "${OUTPUT_PATH}" ]; then
+  echo "ERROR:" "$*" >&2
-  echo "Error; could not determine the desired location at which to create a Go-compatible workspace. Please update GOPATH to specify the desired destination directory"
   exit 1
-fi
+}
 
-function confirm() {
+#####################################################################
+# Print the message to stderr with the prefix WARN
+#####################################################################
+function log_WARN() {
+  echo "WARN:" "$*" >&2
+}
+
+
+#####################################################################
+# Print the message with the prefix INFO.
+#####################################################################
+function log_INFO() {
+  echo "INFO:" "$*"
+}
+
+
+#####################################################################
+# Find the root project directory of this repo. This is done by
+# finding the directory of where this script lives and then go up one
+# directory to check the ".repo" directory exist. If not, keep going
+# up until we find the ".repo" file or we reached to the filesystem
+# root. Project root directory is printed to stdout.
+#####################################################################
+function root_dir() (
+  local dir
+  if ! dir="$("${readlink}" -e $(dirname "$0"))"; then
+    log_FATAL "failed to read the script's current directory."
+  fi
+
+  dir=${dir}/../../..
+  if ! dir="$("${readlink}" -e "${dir}")"; then
+    log_FATAL "Cannot find the root project directory"
+  fi
+
+  echo "${dir}"
+)
+
+
+#####################################################################
+# executes a shell command by printing out to the screen first and
+# then evaluating the command.
+#####################################################################
+function execute() {
+  echo "$@"
+  eval "$@"
+}
+
+
+#####################################################################
+# Returns the source directory of a passed in path from BIND_PATHS
+# array.
+#####################################################################
+function bind_path_src_dir() (
+  local -r bind_path="$1"
+  echo "${bind_path/%|*/}"
+)
+
+
+#####################################################################
+# Returns the destination directory of a passed in path from
+# BIND_PATHS array.
+#####################################################################
+function bind_path_dst_dir() (
+  local -r bind_path="$1"
+  echo  "${bind_path/#*|}"
+)
+
+
+#####################################################################
+# Executes the bindfs command in linux. Expects $1 to be src
+# directory and $2 to be destination directory.
+#####################################################################
+function linux_bind_dir() (
+  execute bindfs "$1" "$2"
+)
+
+#####################################################################
+# Executes the fusermount -u command in linux. Expects $1 to be the
+# destination directory.
+#####################################################################
+function linux_unbind_dir() (
+  execute fusermount -u "$1"
+)
+
+#####################################################################
+# Executes the bindfs command in darwin. Expects $1 to be src
+# directory and $2 to be destination directory.
+#####################################################################
+function darwin_bind_dir() (
+  execute bindfs -o allow_recursion -n "$1" "$2"
+)
+
+
+#####################################################################
+# Execute the umount command in darwin to unbind a directory. Expects
+# $1 to be the destination directory
+#####################################################################
+function darwin_unbind_dir() (
+  execute umount -f "$1"
+)
+
+
+#####################################################################
+# Bind all the paths that are specified in the BIND_PATHS array.
+#####################################################################
+function bind_all() (
+  local src_dir
+  local dst_dir
+
+  for path in ${BIND_PATHS[@]}; do
+    src_dir=$(bind_path_src_dir "${path}")
+
+    dst_dir=$(bind_path_dst_dir "${path}")
+    mkdir -p "${dst_dir}"
+
+    "${bind_dir}" ${src_dir} "${dst_dir}"
+  done
+
+  echo
+  log_INFO "Created GOPATH-compatible directory structure at ${OUTPUT_PATH}."
+)
+
+
+#####################################################################
+# Unbind all the paths that are specified in the BIND_PATHS array.
+#####################################################################
+function unbind_all() (
+  local dst_dir
+  local exit_code=0
+
+  # need to go into reverse since several parent directory may have been
+  # first before the child one.
+  for (( i=${#BIND_PATHS[@]}-1; i>=0; i-- )); do
+    dst_dir=$(bind_path_dst_dir "${BIND_PATHS[$i]}")
+
+    # continue to unmount even one of them fails
+    if ! "${unbind_dir}" "${dst_dir}"; then
+      log_WARN "Failed to umount ${dst_dir}."
+      exit_code=1
+    fi
+  done
+
+  if [[ ${exit_code} -ne 0 ]]; then
+    exit ${exit_code}
+  fi
+
+  echo
+  log_INFO "Unmounted the GOPATH-compatible directory structure at ${OUTPUT_PATH}."
+)
+
+
+#####################################################################
+# Asks the user to create the GOPATH-compatible directory structure.
+#####################################################################
+function confirm() (
   while true; do
     echo "Will create GOPATH-compatible directory structure at ${OUTPUT_PATH}"
     echo -n "Ok [Y/n]?"
@@ -42,48 +193,162 @@ function confirm() {
       if [ "${decision}" == "n" ]; then
         return 1
       else
-        echo "Invalid choice ${decision}; choose either 'y' or 'n'"
+        log_WARN "Invalid choice ${decision}; choose either 'y' or 'n'"
       fi
     fi
   done
+)
+
+
+#####################################################################
+# Help function.
+#####################################################################
+function help() (
+  cat <<EOF
+Mounts the components of soong into a directory structure that Go tools
+and editors expect.
+
+  --help
+    This help
+
+  --bind
+    Create the directory structure that Go tools and editors expect by
+    binding the one to aosp build directory.
+
+  --unbind
+    Reverse operation of bind.
+
+If no flags were specified, the --bind one is selected by default.
+EOF
+)
+
+
+#####################################################################
+# Parse the arguments passed in to this script.
+#####################################################################
+function parse_arguments() {
+  while [[ -n "$1" ]]; do
+    case "$1" in
+          --bind)
+            ACTION="bind"
+            shift
+            ;;
+          --unbind)
+            ACTION="unbind"
+            shift
+            ;;
+          --help )
+            help
+            shift
+            exit 0
+            ;;
+          *)
+            log_WARN "Unknown option: $1"
+            help
+            exit 1
+            ;;
+    esac
+  done
+
+  if [[ -z "${ACTION}" ]]; then
+    ACTION=bind
+  fi
 }
 
-function bindAll() {
-  bindOne "${ANDROID_PATH}/build/blueprint" "${OUTPUT_PATH}/src/github.com/google/blueprint"
-  bindOne "${ANDROID_PATH}/build/soong" "${OUTPUT_PATH}/src/android/soong"
 
-  bindOne "${ANDROID_PATH}/art/build" "${OUTPUT_PATH}/src/android/soong/art"
+#####################################################################
-  bindOne "${ANDROID_PATH}/external/golang-protobuf" "${OUTPUT_PATH}/src/github.com/golang/protobuf"
+# Verifies that a list of required binaries are installed in the
-  bindOne "${ANDROID_PATH}/external/llvm/soong" "${OUTPUT_PATH}/src/android/soong/llvm"
+# host in order to run this script.
-  bindOne "${ANDROID_PATH}/external/clang/soong" "${OUTPUT_PATH}/src/android/soong/clang"
+#####################################################################
-  echo
+function check_exec_existence() (
-  echo "Created GOPATH-compatible directory structure at ${OUTPUT_PATH}"
+  function check() {
-}
+    if ! hash "$1" &>/dev/null; then
+      log_FATAL "missing $1"
+    fi
+  }
 
-function bindOne() {
+  local bins
-  #causes $newPath to mirror $existingPath
+  case "${os_type}" in
-  existingPath="$1"
-  newPath="$2"
-  mkdir -p "$newPath"
-  case $(uname -s) in
     Darwin)
-      echoAndDo bindfs -o allow_recursion -n "${existingPath}" "${newPath}"
+      bins=("bindfs" "greadlink")
       ;;
     Linux)
-      echoAndDo bindfs "${existingPath}" "${newPath}"
+      bins=("bindfs" "fusermount")
       ;;
+    *)
+      log_FATAL "${os_type} is not a recognized system."
   esac
+
+  for bin in "${bins[@]}"; do
+    check "${bin}"
+  done
+)
+
+
+function main() {
+  parse_arguments "$@"
+
+  check_exec_existence
+
+  if [[ "${ACTION}" == "bind" ]]; then
+    if confirm; then
+      echo
+      bind_all
+    else
+      echo "skipping due to user request"
+      exit 1
+    fi
+  else
+    echo
+    unbind_all
+  fi
 }
 
-function echoAndDo() {
+readonly os_type="$(uname -s)"
-  echo "$@"
+case "${os_type}" in
-  eval "$@"
+  Darwin)
-}
+    bind_dir=darwin_bind_dir
+    unbind_dir=darwin_unbind_dir
+    readlink=greadlink
+    ;;
+  Linux)
+    bind_dir=linux_bind_dir
+    unbind_dir=linux_unbind_dir
+    readlink=readlink
+    ;;
+    *)
+    log_FATAL "${os_type} is not a recognized system."
+esac
+readonly bind_dir
+readonly unbind_dir
+readonly readlink
 
-if confirm; then
+
-  echo
+if ! ANDROID_PATH="$(root_dir)"; then
-  bindAll
+  log_FATAL "failed to find the root of the repo checkout"
-else
-  echo "skipping due to user request"
-  exit 1
 fi
+readonly ANDROID_PATH
+
+#if GOPATH contains multiple paths, use the first one
+if ! OUTPUT_PATH="$(echo ${GOPATH} | sed 's/\:.*//')"; then
+  log_FATAL "failed to extract the first GOPATH environment variable"
+fi
+readonly OUTPUT_PATH
+if [ -z "${OUTPUT_PATH}" ]; then
+  log_FATAL "Could not determine the desired location at which to create a" \
+            "Go-compatible workspace. Please update GOPATH to specify the" \
+            "desired destination directory."
+fi
+
+# Below are the paths to bind from src to dst. The paths are separated by |
+# where the left side is the source and the right side is destination.
+readonly BIND_PATHS=(
+  "${ANDROID_PATH}/build/blueprint|${OUTPUT_PATH}/src/github.com/google/blueprint"
+  "${ANDROID_PATH}/build/soong|${OUTPUT_PATH}/src/android/soong"
+  "${ANDROID_PATH}/art/build|${OUTPUT_PATH}/src/android/soong/art"
+  "${ANDROID_PATH}/external/golang-protobuf|${OUTPUT_PATH}/src/github.com/golang/protobuf"
+  "${ANDROID_PATH}/external/llvm/soong|${OUTPUT_PATH}/src/android/soong/llvm"
+  "${ANDROID_PATH}/external/clang/soong|${OUTPUT_PATH}/src/android/soong/clang"
+)
+
+main "$@"