sof/.github/workflows/shallowfetchPRcommits.sh

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#!/bin/sh
# SPDX-License-Identifier: BSD-3-Clause
set -e
# This script fetches Pull Request commits missing from a shallow clone
# and creates a PR_SHAs.txt file. This script has a limit of 500 commits but the
# github API used has a lower limit of 250 commits.
# It does not rely on git merge-bases which basically don't work with
# shallow clones:
# https://github.com/thesofproject/linux/issues/2556
# Design goals:
#
# - Keep the code short and as simple as possible. No one is interested
# in maintaining this sort of script.
#
# - Fast and accurate for small Pull Requests
#
# - For large Pull Requests _with merges_ the only objective is to
# complete in a reasonable time; say less than 10 minutes. It's very
# unlikely will look at 250 checkpatch results and time optimizations
# should not make this script more complex.
# Sample usage:
# $0 thesoftproject/linux 2772
main()
{
local gh_project="$1"
local pr_number="$2"
printf '%s: fetching PR %d for project %s\n' "$0" "$pr_number" "$gh_project"
# As of March 2021, Github's documented limit is 250 commits
# Let's have another cap a 500.
# https://docs.github.com/en/rest/reference/pulls#list-commits-on-a-pull-request
local pagelen PRlen=0
for i in 1 2 3 4 5; do
curl -H 'Accept: application/vnd.github.v3+json' \
"https://api.github.com/repos/$gh_project/pulls/$pr_number/commits?per_page=100&page=$i" \
> commits_"$i".json
pagelen=$(jq length < commits_$i.json)
if [ "$pagelen" -eq 0 ]; then
break
fi
PRlen=$((PRlen + pagelen))
done
printf 'Found %d commits, SHA1 list is in PR_SHAs.txt\n' "$PRlen"
# 'cut' removes double quotes
cat commits_?.json |
jq '.[] | .sha' |
cut -b2-41 > PR_SHAs.txt
# PRlen+1 gets us the merge base for simple, linear histories. For
# pull requests with merges, depth=PRLEN goes already much further
# than needed and +1 makes little difference. It's not clear when
# and for what sort of PRs git fetching individual commits would be
# faster so keep a single and simple fetch for now.
set -x # this command may take a while so show it
git fetch --depth "$((PRlen+1))" "https://github.com/$gh_project" "pull/$pr_number/head"
}
main "$@"