CI: add check of GitHub Action pinned hashes against tag

Add .ci.ghactions.sh script to validate hashes of GitHub Actions against
the declared tag.

Author: dolmen

.ci.ghactions.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+# MIT License
+#
+# Copyright (c) 2026 Olivier Mengué and contributors.
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+#
+# Verify that hashes of GitHub actions match the declared tag in attached comment.
+#
+
+set -euo pipefail
+
+declare -A seen
+status=0
+
+for w in .github/workflows/*.yml
+do
+	sed -n -e '/uses: / s!^ *-\{0,1\} uses: \([^@]*\)@\([0-9a-f][0-9a-f]*\) *# *\(v.*\)$!\1 \2 \3!p' "$w" | while read -r action hash tag
+	do
+		if (( ${seen["$action-$hash-$tag"]:-0} )); then
+			printf "\e[1;32m%s: %s@%s == %s\e[m\n" "$w" "$action" "$tag" "$hash"
+			continue
+		fi
+		seen["$action-$hash-$tag"]=1
+
+		if eval "$( curl -s -H "Accept: application/vnd.github+json" \
+			"https://api.github.com/repos/$action/commits/$tag" | jq -r '.sha == "'"$hash"'"' )"
+		then
+			printf "\e[1;32m%s: %s@%s == %s\e[m\n" "$w" "$action" "$tag" "$hash"
+		else
+			printf "\e[1;31m%s: %s@%s != %s\e[m\n" "$w" "$action" "$tag" "$hash"
+			status=1
+		fi
+	done
+done
+
+exit $status

.github/workflows/main.yml

@@ -19,7 +19,8 @@ jobs:
       - run: ./.ci.gofmt.sh
       - run: ./.ci.govet.sh
       - run: go test -v -race ./...
-  test:
+
+  test-old-go:
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -39,3 +40,9 @@ jobs:
         with:
           go-version: ${{ matrix.go_version }}
       - run: go test -v -race ./...
+
+  check-actions-hashes:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - run: ./.ci.ghactions.sh