#!/bin/bash

# We want to catch any command failure, and exit immediately
set -e

# Download helper for bzr
# Call it with:
#   $1: bzr repo
#   $2: bzr revision
#   $3: output file
# And this environment:
#   BZR      : the bzr command to call
#   BUILD_DIR: path to Buildroot's build dir

repo="${1}"
rev="${2}"
output="${3}"

tmp_dl="$( mktemp "${BUILD_DIR}/.XXXXXX" )"
tmp_output="$( mktemp "${output}.XXXXXX" )"

# Play tic-tac-toe with temp files
# - first, we download to a trashable location (the build-dir)
# - the we move to a temp file in the final location, so it is
#   on the same filesystem as the final file
# - finally, we atomically rename to the final file

ret=1
if ${BZR} export --format=tgz "${tmp_dl}" "${repo}" -r "${rev}"; then
    if mv "${tmp_dl}" "${tmp_output}"; then
        mv "${tmp_output}" "${output}"
        ret=0
    fi
fi

# Cleanup
rm -f "${tmp_dl}" "${tmp_output}"
exit ${ret}