githooks: Create commit message template with prepare-commit-msg

Resolves https://tracker.ceph.com/issues/51537

githooks/prepare-commit-msg

@@ -0,0 +1,41 @@
+#!/usr/bin/sh
+#
+# An example hook script to prepare the commit log message.
+# Called by "git commit" with the name of the file that has the
+# commit message, followed by the description of the commit
+# message's source.  The hook's purpose is to edit the commit
+# message file.  If the hook fails with a non-zero status,
+# the commit is aborted.
+#
+# To enable this hook, rename this file to "prepare-commit-msg".
+
+# This hook includes three examples. The first one removes the
+# "# Please enter the commit message..." help message.
+#
+# The second includes the output of "git diff --name-status -r"
+# into the message, just before the "git status" output.  It is
+# commented because it doesn't cope with --amend or with squashed
+# commits.
+#
+# The third example adds a Signed-off-by line to the message, that can
+# still be edited.  This is rarely a good idea.
+
+COMMIT_MSG_FILE=$1
+COMMIT_SOURCE=$2
+SHA1=$3
+
+# /usr/bin/perl -i.bak -ne 'print unless(m/^. Please enter the commit message/..m/^#$/)' "$COMMIT_MSG_FILE"
+
+if [[ -z "$COMMIT_SOURCE" ]]
+then
+  echo "# Please enter the commit message for your changes. " > "$COMMIT_MSG_FILE"
+  for FILE in $(git diff --cached --name-only -r)
+  do
+    # According to files changed the commit message would start "<project_name>: <commit_message>"
+    # src/<project>/file.txt - "<project>:"
+    # file.txt               - "file.txt:"
+    # <project>/file.txt     - "<project>:" 
+    echo "# $FILE: <commit_message>" | sed -E 's|src/+||g' | sed -r 's/(.*)(\/[a-z0-9.-]+)/\1 /' >> "$COMMIT_MSG_FILE"  
+  done
+fi
+