ci: separate whitespace check script

The `check-whitespace` CI job is only available as a GitHub action. To
help enable this job with other CI providers, first separate the logic
performing the whitespace check into its own script. In subsequent
commits, this script is further generalized allowing its reuse.

Helped-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 78 insertions, 64 deletions

diff --git a/.github/workflows/check-whitespace.yml b/.github/workflows/check-whitespace.yml
index a3a6913ecc..d0a78fc426 100644
--- a/.github/workflows/check-whitespace.yml
+++ b/.github/workflows/check-whitespace.yml
@@ -26,67 +26,7 @@ jobs:
     - name: git log --check
       id: check_out
       run: |
-        baseSha=${{github.event.pull_request.base.sha}}
-        problems=()
-        commit=
-        commitText=
-        commitTextmd=
-        goodParent=
-        while read dash sha etc
-        do
-          case "${dash}" in
-          "---") # Line contains commit information.
-            if test -z "${goodParent}"
-            then
-              # Assume the commit has no whitespace errors until detected otherwise.
-              goodParent=${sha}
-            fi
-            commit="${sha}"
-            commitText="${sha} ${etc}"
-            commitTextmd="[${sha}](https://github.com/${{ github.repository }}/commit/${sha}) ${etc}"
-            ;;
-          "")
-            ;;
-          *) # Line contains whitespace error information for current commit.
-            if test -n "${goodParent}"
-            then
-              problems+=("1) --- ${commitTextmd}")
-              echo ""
-              echo "--- ${commitText}"
-              goodParent=
-            fi
-            case "${dash}" in
-            *:[1-9]*:) # contains file and line number information
-              dashend=${dash#*:}
-              problems+=("[${dash}](https://github.com/${{ github.repository }}/blob/${commit}/${dash%%:*}#L${dashend%:}) ${sha} ${etc}")
-              ;;
-            *)
-              problems+=("\`${dash} ${sha} ${etc}\`")
-              ;;
-            esac
-            echo "${dash} ${sha} ${etc}"
-            ;;
-          esac
-        done <<< $(git log --check --pretty=format:"---% h% s" ${baseSha}..)
-
-        if test ${#problems[*]} -gt 0
-        then
-          if test -z "${goodParent}"
-          then
-            goodParent=${baseSha: 0:7}
-          fi
-          echo "🛑 Please review the Summary output for further information."
-          echo "### :x: A whitespace issue was found in one or more of the commits." >$GITHUB_STEP_SUMMARY
-          echo "" >>$GITHUB_STEP_SUMMARY
-          echo "Run these commands to correct the problem:" >>$GITHUB_STEP_SUMMARY
-          echo "1. \`git rebase --whitespace=fix ${goodParent}\`" >>$GITHUB_STEP_SUMMARY
-          echo "1. \`git push --force\`" >>$GITHUB_STEP_SUMMARY
-          echo " " >>$GITHUB_STEP_SUMMARY
-          echo "Errors:" >>$GITHUB_STEP_SUMMARY
-          for i in "${problems[@]}"
-          do
-            echo "${i}" >>$GITHUB_STEP_SUMMARY
-          done
-
-          exit 2
-        fi
+        ./ci/check-whitespace.sh \
+          "${{github.event.pull_request.base.sha}}" \
+          "$GITHUB_STEP_SUMMARY" \
+          "https://github.com/${{github.repository}}"
diff --git a/ci/check-whitespace.sh b/ci/check-whitespace.sh
new file mode 100755
index 0000000000..9cc496da40
--- /dev/null
+++ b/ci/check-whitespace.sh
@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+
+baseCommit=$1
+outputFile=$2
+url=$3
+
+problems=()
+commit=
+commitText=
+commitTextmd=
+goodParent=
+
+while read dash sha etc
+do
+	case "${dash}" in
+	"---") # Line contains commit information.
+		if test -z "${goodParent}"
+		then
+			# Assume the commit has no whitespace errors until detected otherwise.
+			goodParent=${sha}
+		fi
+
+		commit="${sha}"
+		commitText="${sha} ${etc}"
+		commitTextmd="[${sha}](${url}/commit/${sha}) ${etc}"
+		;;
+	"")
+		;;
+	*) # Line contains whitespace error information for current commit.
+		if test -n "${goodParent}"
+		then
+			problems+=("1) --- ${commitTextmd}")
+			echo ""
+			echo "--- ${commitText}"
+			goodParent=
+		fi
+
+		case "${dash}" in
+		*:[1-9]*:) # contains file and line number information
+			dashend=${dash#*:}
+			problems+=("[${dash}](${url}/blob/${commit}/${dash%%:*}#L${dashend%:}) ${sha} ${etc}")
+			;;
+		*)
+			problems+=("\`${dash} ${sha} ${etc}\`")
+			;;
+		esac
+		echo "${dash} ${sha} ${etc}"
+		;;
+	esac
+done <<< "$(git log --check --pretty=format:"---% h% s" "${baseCommit}"..)"
+
+if test ${#problems[*]} -gt 0
+then
+	if test -z "${goodParent}"
+	then
+		goodParent=${baseCommit: 0:7}
+	fi
+
+	echo "🛑 Please review the Summary output for further information."
+	echo "### :x: A whitespace issue was found in one or more of the commits." >"$outputFile"
+	echo "" >>"$outputFile"
+	echo "Run these commands to correct the problem:" >>"$outputFile"
+	echo "1. \`git rebase --whitespace=fix ${goodParent}\`" >>"$outputFile"
+	echo "1. \`git push --force\`" >>"$outputFile"
+	echo " " >>"$outputFile"
+	echo "Errors:" >>"$outputFile"
+
+	for i in "${problems[@]}"
+	do
+		echo "${i}" >>"$outputFile"
+	done
+
+	exit 2
+fi