zulip/tools/push-to-pull-request

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#!/usr/bin/env bash
set -e
usage () {
cat >&2 <<EOF
usage: $0 PULL_REQUEST_ID [REMOTE]
Force-push our HEAD to the given GitHub pull request branch.
Useful for a maintainer to run just before pushing to master,
after tweaking the branch and/or rebasing to latest. This causes
GitHub to see the subsequent push to master as representing a
merge of the PR, rather than requiring the PR to be manually
(and to the casual observer misleadingly) closed instead.
REMOTE defaults to the value of the Git config variable
\`zulip.zulipRemote\` if set, else to \`upstream\`.
See also \`reset-to-pull-request\`.
EOF
exit 1
}
remote_default="$(git config zulip.zulipRemote || echo upstream)"
pseudo_remote="$(git config zulip.prPseudoRemote || echo)"
pr_id="$1"
remote="${2:-"$remote_default"}"
if [ -z "$pr_id" ]; then
usage
fi
if ! jq --version >/dev/null 2>&1; then
cat >&2 <<EOF
error: not found: jq
push-to-pull-request requires the \`jq\` utility; you should install it.
Try:
sudo apt install jq
EOF
exit 1
fi
remote_url="$(git remote get-url --push "$remote")"
repo_fq="$(echo "$remote_url" | perl -lne 'print $1 if (
m, ^ git\@github\.com:
([^/]+ / [^/]+?)
(?:\.git)?
$ ,x )')"
if [ -z "$repo_fq" ]; then
# We're pretty specific about what we expect the URL to look like;
# there are probably more cases we could legitimately cover, which
# we can add if/when they come up for someone.
echo "error: couldn't parse remote URL as GitHub repo: $remote_url" >&2
exit 1
fi
# See https://developer.github.com/v3/pulls/#get-a-single-pull-request .
# This is the old REST API; the new GraphQL API does look neat, but it
# seems to require authentication even for simple lookups of public data,
# and that'd be a pain for a simple script like this.
pr_url=https://api.github.com/repos/"${repo_fq}"/pulls/"${pr_id}"
pr_details="$(curl -s "$pr_url")"
pr_jq () {
echo "$pr_details" | jq "$@"
}
if [ "$(pr_jq -r .message)" = "Not Found" ]; then
echo "error: invalid PR URL: $pr_url" >&2
exit 1
fi
if [ "$(pr_jq .maintainer_can_modify)" != "true" ]; then
# This happens when the PR has already been merged or closed, or
# if the contributor has turned off the (default) setting to allow
# maintainers of the target repo to push to their PR branch.
#
# The latter seems to be rare (in Greg's experience doing the
# manual equivalent of this script for many different
# contributors, none have ever chosen this setting), but give a
# decent error message if it does happen.
echo "error: PR already closed, or contributor has disallowed pushing to branch" >&2
exit 1
fi
pr_head_repo_fq="$(pr_jq -r .head.repo.full_name)"
pr_head_refname="$(pr_jq -r .head.ref)"
tracking_ref=
if [ -n "$pseudo_remote" ]; then
tracking_ref=$(git rev-parse -q --verify --symbolic refs/remotes/"$pseudo_remote"/"$pr_id" || echo)
fi
set -x
git push git@github.com:"$pr_head_repo_fq" +@:"$pr_head_refname"
{ set +x; } 2>&-
if [ -n "$tracking_ref" ]; then
set -x
git update-ref "$tracking_ref" @
fi