From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Mon, 28 Apr 2025 08:41:39 +0000 (+1000)
Subject: fetch_trees: use ls-remote to check the ref SHA
X-Git-Url: https://git.ozlabs.org/?a=commitdiff_plain;h=9c0f58ab626fbb1d0eebc6c5da8d877ca67defce;p=next-scripts

fetch_trees: use ls-remote to check the ref SHA

before fetching = - in the hope that that is a much lower
overhead operation on the remote
---

diff --git a/fetch_trees b/fetch_trees
index a6276b3..92accdd 100755
--- a/fetch_trees
+++ b/fetch_trees
@@ -22,9 +22,27 @@ if [ "$1" = '-s' ]; then
 	shift
 fi
 
+# shellcheck disable=SC2317
 fetch_git()
 {
-	git fetch "$1"
+	local name="$1" branch="$2" old_sha="$3" new_sha
+
+	if ! new_sha=$(git ls-remote "$name" "refs/heads/$branch") ||
+	   [ -z "$new_sha" ]; then
+		printf '%s: Could not fetch %s branch %s\n' 'fetch_git' "$name" "$branch" >&2
+		printf '%s\n' "$old_sha"
+		return
+	fi
+	new_sha="${new_sha%%"${_TAB}"*}"
+	if [ "$new_sha" = "$old_sha" ]; then
+		printf '%s\n' "$old_sha"
+		return
+	fi
+	if git fetch "$name"; then
+		git rev-parse --verify "$name/$branch"
+	else
+		printf '%s\n' "$old_sha"
+	fi
 }
 
 trees="$*"
@@ -57,8 +75,7 @@ for name in $trees; do
 	if [ "$tfun" = 'function' ]; then
 		branch=$(get_remote_branch "$name")
 		old_sha=$(git rev-parse --quiet --verify "$name/$branch")
-		"$fun" "$name"
-		new_sha=$(git rev-parse --verify "$name/$branch")
+		new_sha=$("$fun" "$name" "$branch" "$old_sha")
 		check_dups "$name" origin/master "$new_sha"
 		if ! [ "$new_sha" = "$old_sha" ]; then
 			"$tools_dir"/check_commits ^origin/master "$old_sha..$new_sha"