71 lines
2.2 KiB
Bash
Executable File
71 lines
2.2 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Copyright 2023 The cert-manager Authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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set -o errexit
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set -o nounset
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set -o pipefail
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# This script is used to lock a file while it is being downloaded. It prevents
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# multiple processes from downloading the same file at the same time or from reading
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# a half-downloaded file.
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# We need this solution because we have recursive $(MAKE) calls in our makefile
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# which each will try to download a set of tools. To prevent them from all downloading
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# the same files, we re-use the same downloads folder for all $(MAKE) invocations and
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# use this script to deduplicate the download processes.
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finalfile="$1"
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lockfile="$finalfile.lock"
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# On OSX, flock is not installed, we just skip locking in that case,
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# this means that running verify in parallel without downloading all
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# tools first will not work.
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flock_installed=$(command -v flock >/dev/null && echo "yes" || echo "no")
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if [[ "$flock_installed" == "yes" ]]; then
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mkdir -p "$(dirname "$lockfile")"
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touch "$lockfile"
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exec {FD}<>"$lockfile"
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# wait for the file to be unlocked
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if ! flock -x $FD; then
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echo "Failed to obtain a lock for $lockfile"
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exit 1
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fi
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fi
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# now that we have the lock, check if file is already there
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if [[ -e "$finalfile" ]]; then
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exit 0
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fi
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# use a temporary file to prevent Make from thinking the file is ready
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# while in reality is is only a partial download
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# shellcheck disable=SC2034
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outfile="$finalfile.tmp"
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finish() {
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rv=$?
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if [[ $rv -eq 0 ]]; then
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mv "$outfile" "$finalfile"
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echo "[info]: downloaded $finalfile"
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else
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rm -rf "$outfile" || true
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rm -rf "$finalfile" || true
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fi
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rm -rf "$lockfile" || true
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}
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trap finish EXIT SIGINT
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