24cb4c110aThe fork's copies of long-lived branches (demo-20, totara-19, lms) drifted over a thousand commits behind upstream because only the default branch was ever synced. Fast-forward each branch present on both remotes straight from upstream's ref and push them in one go; skip and warn on divergence, and leave a local copy alone if it carries commits of its own. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
99 lines
3.7 KiB
Shell
Executable file
99 lines
3.7 KiB
Shell
Executable file
#!/usr/bin/env zsh
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# Bring the default branch up to date in a fork-model repo, and keep my fork's
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# copy of it aligned: fast-forward it from whichever remote owns it, then push
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# it to origin. Then do the same, without checking anything out, for every
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# other branch the fork mirrors from upstream. Named git-sync and installed on
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# the $PATH, so git finds it as `git sync`.
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set -e
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git rev-parse --git-dir > /dev/null
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# The branch belongs to upstream in a fork, and to origin when there is no
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# fork in play.
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if git remote get-url upstream > /dev/null 2>&1; then
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source_remote=upstream
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else
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source_remote=origin
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fi
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if ! git remote get-url origin > /dev/null 2>&1; then
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echo "git sync: no 'origin' remote to sync" >&2
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exit 1
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fi
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# Ask the server which branch is the default rather than reading
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# refs/remotes/<remote>/HEAD. That ref is a cache written at clone time, and
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# git does not refresh it when the default branch changes upstream - which is
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# the whole reason this script exists.
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branch=$(git ls-remote --symref $source_remote HEAD |
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awk '/^ref:/ { sub("refs/heads/", "", $2); print $2; exit }')
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if [[ -z $branch ]]; then
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echo "git sync: could not work out the default branch of $source_remote" >&2
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exit 1
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fi
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echo "Syncing $branch from $source_remote"
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git fetch --prune $source_remote
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# Re-point the cached HEADs at what the server just told us, so `git
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# default-branch` and nvim's diff-against-branch prompt agree with this script.
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git remote set-head origin --auto > /dev/null
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if [[ $source_remote != origin ]]; then
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git remote set-head $source_remote --auto > /dev/null
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fi
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# Be explicit about what the local branch tracks. A bare `git switch` has to
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# guess, and refuses to when several remotes carry the same branch name - which
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# they do as soon as a colleague's fork is added as a remote.
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if git show-ref --verify --quiet refs/heads/$branch; then
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git switch $branch
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elif git show-ref --verify --quiet refs/remotes/origin/$branch; then
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# Track origin, not upstream: this script keeps the fork's copy current, and
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# it means a stray `git push` here goes somewhere I can actually write to.
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git switch --create $branch --track origin/$branch
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else
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git switch --create $branch --track $source_remote/$branch
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fi
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# Never a merge commit: if the default branch has diverged locally, that is
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# something to look at, not something to paper over.
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git merge --ff-only $source_remote/$branch
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if [[ $source_remote == origin ]]; then
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exit 0
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fi
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git push origin $branch
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# Every branch that exists on both remotes is one the fork mirrors (release
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# branches, demo branches), so keep those current too. Branches only on
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# upstream are colleagues' work, not mine to copy. Nothing is checked out here:
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# origin is updated straight from upstream's ref, and a local copy is
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# fast-forwarded in place if there is one.
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git fetch --prune origin
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refspecs=()
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for other in $(git for-each-ref --format='%(refname:strip=3)' refs/remotes/$source_remote/); do
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[[ $other == $branch || $other == HEAD ]] && continue
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git show-ref --verify --quiet refs/remotes/origin/$other || continue
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if git merge-base --is-ancestor origin/$other $source_remote/$other; then
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# Fast-forward a local copy too, but leave one with local commits
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# alone: that is my in-progress work, not drift.
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if git show-ref --verify --quiet refs/heads/$other &&
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git merge-base --is-ancestor $other $source_remote/$other; then
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git fetch . $source_remote/${other}:refs/heads/$other
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fi
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refspecs+=("$source_remote/${other}:refs/heads/$other")
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else
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echo "git sync: skipping $other - origin has diverged from $source_remote" >&2
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fi
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done
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if (( ${#refspecs} )); then
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git push origin "${refspecs[@]}"
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fi
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