#!/bin/bash
# Copyright 2020 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

#### CATEGORY=Software delivery
### unarchive a Fuchsia package archive in FAR format

## Usage: fx unarchive-package <.far file> [ --out-dir <output directory> ]
##
## The script unarchives a Fuchsia package archive in FAR format and puts the
## contents in the output directory. Files in the package will be renamed and
## arranged according to its meta/contents file.
##
## The command will by default create a directory with the same name as the .far
## file under the current directory, which can be overridden by --output-dir
## option. If --output-dir is an existing directory, then a sub-directory with
## the same name as the .far file will be created.
##
## Note: although a Fuchsia package archive is in FAR format, not all .far files
## are valid Fuchsia packages! To interact with any .far files, use `fx far`.
## Also, This tool only works with fuchsia package archives, although it could be
## extended in the future to work with plain fuchsia packages.
##
## Example:
##   $ fx unarchive-package foo.far
##   Unarchived foo.far under foo
##
##   # directory "foo" will be created as
##   $ tree foo
##   foo
##   ├── bin
##   │   └── foo
##   ├── lib
##   │   ├── ld.so.1
##   │   ├── libc++abi.so.1
##   │   ├── libc++.so.2
##   │   ├── libfdio.so
##   │   └── libunwind.so.1
##   └── meta
##       ├── contents
##       ├── foo_component.cmx
##       └── package
##
##   $ fx unarchive-package foo.far --out-dir foo2  # assuming foo2 doesn't exist
##   Unarchived foo.far under foo2
##
##   $ fx unarchive-package foo.far --out-dir /tmp
##   Unarchived foo.far under /tmp/foo

source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/../lib/vars.sh || exit $?
fx-config-read

# Cleanup at exit
function cleanup {
  [[ ${TMP_META_FAR} && -f ${TMP_META_FAR} ]] && rm "${TMP_META_FAR}"
}
trap cleanup EXIT

# Useful function
function die {
  fx-error "$@"
  exit 1
}

# `fx far` wrapper
function far {
  local far="${FUCHSIA_BUILD_DIR}/host-tools/far"
  if [[ ! -f ${far} ]]; then
    fx-error "\"far\" host tool not found."
    fx-error "Run \"fx build\" to build host tools."
    exit 1
  fi

  "${far}" "$@" || exit $?
}

# Parse arguments
while [[ $# -ge 1 ]]; do
  case "$1" in
    -h|--help)
      fx-command-help
      exit 0
      ;;
    --out-dir)
      shift
      [[ ! $1 ]] && die "--out-dir requires an argument after it"
      OUTPUT="$1"
      ;;
    -*)
      die "Cannot understand option $1"
      ;;
    *)
      [[ ${FAR_FILE} ]] && die "Only one .far file can be provided"
      FAR_FILE="$1"
  esac
  shift
done

[[ ! ${FAR_FILE} ]] && fx-command-help && die "No input provided"
[[ ! -e ${FAR_FILE} ]] && die "${FAR_FILE} does not exist"

PKG_NAME="$(basename "${FAR_FILE%.far}")"
if [[ ${OUTPUT} ]]; then
  # Append $PKG_NAME if $OUTPUT is existing, e.g. /tmp
  [[ -e ${OUTPUT} ]] && OUTPUT="${OUTPUT}/${PKG_NAME}"
else
  # By default output to the current directory
  OUTPUT="${PKG_NAME}"
fi
[[ -e ${OUTPUT} ]] && die "${OUTPUT} already exists"

TMP_META_FAR="$(mktemp)"

# It first extracts meta.far from $FAR_FILE and then from its contents
# file we lookup the blob ID to extract that particular file indexed by
# blob ID under its readable name.
far extract-file "--archive=${FAR_FILE}" --file=meta.far "--output=${TMP_META_FAR}"
far extract "--archive=${TMP_META_FAR}" "--output=${OUTPUT}"

[[ ! -f ${OUTPUT}/meta/contents ]] && die "Cannot find ${OUTPUT}/meta/contents"

while IFS= read -r line; do
  # Each line is of the format "$dst=$src" where $dst is a readable name like "lib/libfoo.so"
  # and $src is a blob sha1.
  dst="${line%=*}"
  src="${line##*=}"

  dir="$(dirname "${OUTPUT}/${dst}")"
  if [[ ! -d ${dir} ]]; then
    mkdir -p "${dir}"
  fi
  far extract-file "--archive=${FAR_FILE}" "--file=${src}" "--output=${OUTPUT}/${dst}"
done < "${OUTPUT}/meta/contents"

echo "Unarchived ${FAR_FILE} under ${OUTPUT}"