Adding diff script

.github/workflows/ci.yaml

@@ -57,6 +57,15 @@ jobs:
           # Run buf format
           buf format proto --diff --exit-code
 
+  # diff check against c4t branch to catch breaking changes
+  diff-c4t:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the repo
+        uses: actions/checkout@v4
+      - name: Run diff against branch
+        run: scripts/diff_against_branch.sh
+
   # Push the draft branch to buf.build
   bsr-push-draft:
     runs-on: ubuntu-latest

scripts/diff_against_branch.sh

@@ -0,0 +1,104 @@
+#!/bin/bash 
+
+## This file will do a diff against the provided branch (defaults to c4t) for added files
+## As the definition of the versioning is to always create a new version if a file has been changed
+## we make sure that every structure change is a breaking change. 
+##
+## But at the same time it's hard to see the actual changes in the new version as there is no 
+## history of changes. Therefore this script exists which will:
+##
+## * Get the *added* files out of the git history
+## * Extract the version 
+## * Check if a file with version-1 exists in the origin branch
+## * Do a diff against the other file
+##
+## * Get the *modified* files 
+## * Check if there are any structural changes
+## * Throw an error in case a structural change is detected
+
+declare -a ERROR_FILES
+ORIGIN=${1:-c4t}
+
+git fetch origin $ORIGIN
+
+function check_added_file {
+	FILE=$1
+
+	FILE_VERSION=$(echo $FILE | grep -oP "/v[0-9]+/" | cut -d"v" -f2 | cut -d"/" -f1)
+
+	if [[ "$FILE_VERSION" == "1" ]] ; then
+		# Skip it as it's newly introduced
+		return
+	fi
+
+	OTHER_FILE=$(echo $FILE | sed -e "s#/v$FILE_VERSION/#/v$(( FILE_VERSION - 1))/#")
+
+	echo
+	echo "#############################################################################"
+	echo "## Detected newly added file: $FILE" 
+	echo "## Version: $FILE_VERSION" 
+	echo "## Comparing against $ORIGIN/$OTHER_FILE"
+	echo "#############################################################################"
+	echo
+
+	GIT_PAGER=cat git diff --exit-code origin/$ORIGIN:$OTHER_FILE $FILE
+	if [[ "$?" == "0" ]] ; then
+		echo "## No change detected! (weird?)"
+	fi
+}
+
+function check_modified_file {
+	FILE=$1
+	OTHER_FILE=$FILE
+
+	echo
+	echo "#############################################################################"
+	echo "## Detected modified file: $FILE" 
+	echo "## Comparing against $ORIGIN/$OTHER_FILE"
+	echo "#############################################################################"
+	echo
+
+	GIT_PAGER=cat git diff --exit-code origin/$ORIGIN:$OTHER_FILE $FILE
+	if [[ "$?" == "0" ]] ; then
+		echo "## No change detected! (weird?)"
+	fi
+
+	# Check here if the file has any structure modifications, if yes return
+	# some value != 0 for an automated script to fail if we detect any modifications
+	# against the c4t branch	
+	diff -w -B - <(git show origin/$ORIGIN:$OTHER_FILE | sed -e "s#//.*##g") < <(cat $FILE | sed -e "s#//.*##g") > /dev/null
+	if [[ "$?" != "0" ]] ; then
+		echo
+		echo "## ❌ [FAIL] ERROR: Structural change detected in already existing file: $FILE"
+		ERROR_FILES+=("$FILE")
+	else
+		echo
+		echo "## ✅ [PASS] INFO: No structural change detected. The changes should only be in the comments."
+	fi 
+}
+
+while read FILE ; do
+	check_added_file $FILE
+done < <(git diff --name-status origin/$ORIGIN | grep -P "^A.*" | grep -oP "proto/.*")
+
+
+while read FILE ; do
+	check_modified_file $FILE
+done < <(git diff --name-status origin/$ORIGIN | grep -P "^M.*" | grep -oP "proto/.*")
+
+if [ ${#ERROR_FILES[@]} -gt 0 ] ; then
+	echo
+	echo "#############################################################################"
+	echo "## ❌ Found ${#ERROR_FILES[@]} errors while doing the diff"
+	echo "## Please check the following files: "
+	for file in ${ERROR_FILES[@]} ; do
+		echo "## -> $file"
+	done
+	echo "#############################################################################"
+	exit 1
+fi
+
+echo
+echo "##########################"
+echo "## ✅ No issues found!  ##"
+echo "##########################"