From 41b0b69231a0a3428f3874f3cf3b957eb8580100 Mon Sep 17 00:00:00 2001
From: Midgard <midgard@zeus.ugent.be>
Date: Mon, 23 May 2022 14:35:29 +0200
Subject: [PATCH] Improve

---
 README.md     | 29 +++++++++++++++++++++++-----
 git-mirror.sh | 53 +++++++++++++++++++++++++++++++++++----------------
 2 files changed, 61 insertions(+), 21 deletions(-)

diff --git a/README.md b/README.md
index f5f59a2..1be2945 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,19 @@
 
 Run this script to synchronize a repository once.
 
+## Quick start
+Clone git-mirror somewhere on your system. Create a script like the following in the directory of
+the repository you want to keep mirrored, and configure the variables:
+```bash
+#!/bin/sh
+
+mirror="$HOME/path/to/git-mirror/git-mirror.sh"
+leader="github" # Name of the leader remote
+followers="origin" # Space separated list of names of follower remotes
+
+exec "$mirror" --notor "$(dirname "$0")" $leader $followers
+```
+
 ## Dependencies
 * bash
 * git
@@ -12,7 +25,7 @@ Run this script to synchronize a repository once.
 ./git-mirror.sh <workdir> <leader> <follower...>
 ```
 
-## Get started
+## How to use
 Create a git repo, add remotes for the leader and the followers:
 ```bash
 mkdir ~/git-mirror-my-repo; cd ~/git-mirror-my-repo
@@ -33,15 +46,21 @@ The first remote, `github` in this case, is the leader. The others are followers
 If you want to do this conveniently every now and then, you can create a script like this in your
 repository's directory:
 ```bash
-#!/bin/bash
-mirror="$HOME/git-mirror/git-mirror.sh"
-here="$(dirname "$0")"
-exec "$mirror" --notor "$here" github origin
+#!/bin/sh
+
+mirror="$HOME/path/to/git-mirror/git-mirror.sh"
+leader="github" # Name of the leader remote
+followers="origin" # Space separated list of names of follower remotes
+
+exec "$mirror" --notor "$(dirname "$0")" $leader $followers
 ```
 
 Make sure to make it executable, and gitignore it when relevant. A good idea may be to choose an
 arcane name, like `update--.sh`, and add it to a global gitignore file in `~/.gitignore`.
 
+## Caveat
+If a branch has diverged, it will not be updated. Update it manually in that case.
+
 ## Automate
 To automate mirroring, run it periodically, for example once every 30 minutes. On a *NIX you could
 use cron for this, or write a system service definition for your system supervisor (such as
diff --git a/git-mirror.sh b/git-mirror.sh
index 81dab19..ed5023f 100755
--- a/git-mirror.sh
+++ b/git-mirror.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # git-mirror: Mirror a git repo in leader-followers configuration
-# Copyright © 2019 Midgard
+# Copyright © 2019-2022 Midgard
 #
 # This program is free software: you can redistribute it and/or modify it under the terms of the
 # GNU Affero General Public License as published by the Free Software Foundation, either version 3
@@ -60,10 +60,15 @@ echo "${branches[*]}"
 
 IFS=$'\t'
 
+up_to_date=( )
 errors=( )
 
 error() {
-	echo "XXX $1" >&2
+	tput bold
+	tput setaf 1
+	echo -n "XXX"
+	tput sgr0
+	echo " $1" >&2
 	errors[${#errors[*]}]="$1"
 }
 
@@ -84,33 +89,49 @@ for branchspec in "${branches[@]}"; do
 	if [ "$branch" = HEAD ]; then continue; fi
 
 	for remote in "${followers[@]}"; do
-		echo
-		echo "Updating $remote/$branch"
 
 		follower_ref="refs/remotes/$remote/$branch"
 
+		msg=""
 		if ! ref_exists "$follower_ref"; then
-			echo "Branch doesn't yet exist at remote, creating"
-			git checkout "$leader_sha" --
-			git push "$remote" "+HEAD:$branch" || { error "$remote $branch: failed to push"; continue; }
-
-		elif is_ref_at_sha "$follower_ref" "$leader_sha"; then
-			echo "Already up to date"
-
+			msg="Creating $remote/$branch"
+		elif ! is_ref_at_sha "$follower_ref" "$leader_sha"; then
+			msg="Updating $remote/$branch"
 		else
-			echo "Branch exists at remote, updating"
-			git checkout "$follower_ref" --
-			git merge --ff-only "$leader_sha" || { error "$remote $branch: FF not possible"; continue; }
-			git push "$remote" "+HEAD:$branch" || { error "$remote $branch: failed to push"; continue; }
+			up_to_date[${#up_to_date[*]}]="$remote/$branch"
+		fi
+
+		if [[ -n $msg ]]; then
+			echo
+			tput bold
+			echo "$msg"
+			tput sgr0
+
+			git push "$remote" "+$leader_sha:refs/heads/$branch" || { error "$remote $branch: failed to push"; continue; }
 		fi
 
 	done
 done
 
+if [[ "${#up_to_date[*]}" -gt 0 ]]; then
+	echo
+	echo "Already up to date:"
+	echo "${up_to_date[@]}"
+fi
+
 echo
 if [[ "${#errors[*]}" -gt 0 ]]; then
+	tput bold
+	tput setaf 1
 	echo "Errors:"
-	echo "${errors[@]}"
+	tput sgr0
+	tput bold
+	for (( i=0; i < ${#errors[*]}; i++ )); do
+		echo "${errors[$i]}"
+	done
+	tput sgr0
+
+	exit 1
 else
 	echo "No errors."
 fi