#!/bin/bash

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

# Download helper for wget
# Call it with:
#   $1: URL
#   $2: output file
# And this environment:
#   WGET     : the wget command to call
#   BUILD_DIR: path to Buildroot's build dir

url="${1}"
output="${2}"

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)
# - then we copy to a temporary tarball 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 ${WGET} -O "${tmp_dl}" "${url}"; then
    if mv "${tmp_dl}" "${tmp_output}"; then
        mv "${tmp_output}" "${output}"
        ret=0
    fi
fi

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