mklog: handle Signed-off-by, minor cleanup

Consider Signed-off-by lines as part of the ending of the initial
commit to avoid having these in the middle of the log when the
changelog part is injected after.

This is particularly usefull with:

 $ git gcc-commit-mklog --amend -s

that can be used to create the changelog and add the Signed-off-by line.

Also applies most of the shellcheck suggestions on the
prepare-commit-msg hook.

contrib/ChangeLog:

	* mklog.py: Leave SOB lines after changelog.
	* prepare-commit-msg: Apply most shellcheck suggestions.

Signed-off-by: Marc Poulhiès <dkm@kataplop.net>

2 files changed, 39 insertions, 15 deletions

diff --git a/contrib/mklog.py b/contrib/mklog.py
index 0abefcd..effe5aa1 100755
--- a/contrib/mklog.py
+++ b/contrib/mklog.py
@@ -41,7 +41,34 @@ from unidiff import PatchSet
 
 LINE_LIMIT = 100
 TAB_WIDTH = 8
-CO_AUTHORED_BY_PREFIX = 'co-authored-by: '
+
+# Initial commit:
+#   +--------------------------------------------------+
+#   | gccrs: Some title                                |
+#   |                                                  | This is the "start"
+#   | This is some text explaining the commit.         |
+#   | There can be several lines.                      |
+#   |                                                  |<------------------->
+#   | Signed-off-by: My Name <my@mail.com>             | This is the "end"
+#   +--------------------------------------------------+
+#
+# Results in:
+#   +--------------------------------------------------+
+#   | gccrs: Some title                                |
+#   |                                                  |
+#   | This is some text explaining the commit.         | This is the "start"
+#   | There can be several lines.                      |
+#   |                                                  |<------------------->
+#   | gcc/rust/ChangeLog:                              |
+#   |                                                  | This is the generated
+#   |         * some_file (bla):                       | ChangeLog part
+#   |         (foo):                                   |
+#   |                                                  |<------------------->
+#   | Signed-off-by: My Name <my@mail.com>             | This is the "end"
+#   +--------------------------------------------------+
+
+# this regex matches the first line of the "end" in the initial commit message
+FIRST_LINE_OF_END_RE = re.compile('(?i)^(signed-off-by:|co-authored-by:|#)')
 
 pr_regex = re.compile(r'(\/(\/|\*)|[Cc*!])\s+(?P<pr>PR [a-z+-]+\/[0-9]+)')
 prnum_regex = re.compile(r'PR (?P<comp>[a-z+-]+)/(?P<num>[0-9]+)')
@@ -330,10 +357,7 @@ def update_copyright(data):
 
 
 def skip_line_in_changelog(line):
-    if line.lower().startswith(CO_AUTHORED_BY_PREFIX) or line.startswith('#'):
-        return False
-    return True
-
+    return FIRST_LINE_OF_END_RE.match(line) == None
 
 if __name__ == '__main__':
     extra_args = os.getenv('GCC_MKLOG_ARGS')
diff --git a/contrib/prepare-commit-msg b/contrib/prepare-commit-msg
index 48c9dad..1e94706 100755
--- a/contrib/prepare-commit-msg
+++ b/contrib/prepare-commit-msg
@@ -32,11 +32,11 @@ if ! [ -f "$COMMIT_MSG_FILE" ]; then exit 0; fi
 # Don't do anything unless requested to.
 if [ -z "$GCC_FORCE_MKLOG" ]; then exit 0; fi
 
-if [ -z "$COMMIT_SOURCE" ] || [ $COMMIT_SOURCE = template ]; then
+if [ -z "$COMMIT_SOURCE" ] || [ "$COMMIT_SOURCE" = template ]; then
     # No source or "template" means new commit.
     cmd="diff --cached"
 
-elif [ $COMMIT_SOURCE = message ]; then
+elif [ "$COMMIT_SOURCE" = message ]; then
     # "message" means -m; assume a new commit if there are any changes staged.
     if ! git diff --cached --quiet; then
 	cmd="diff --cached"
@@ -44,23 +44,23 @@ elif [ $COMMIT_SOURCE = message ]; then
 	cmd="diff --cached HEAD^"
     fi
 
-elif [ $COMMIT_SOURCE = commit ]; then
+elif [ "$COMMIT_SOURCE" = commit ]; then
     # The message of an existing commit.  If it's HEAD, assume --amend;
     # otherwise, assume a new commit with -C.
-    if [ $SHA1 = HEAD ]; then
+    if [ "$SHA1" = HEAD ]; then
 	cmd="diff --cached HEAD^"
 	if [ "$(git config gcc-config.mklog-hook-type)" = "smart-amend" ]; then
 	    # Check if the existing message still describes the staged changes.
 	    f=$(mktemp /tmp/git-commit.XXXXXX) || exit 1
-	    git log -1 --pretty=email HEAD > $f
-	    printf '\n---\n\n' >> $f
-	    git $cmd >> $f
+	    git log -1 --pretty=email HEAD > "$f"
+	    printf '\n---\n\n' >> "$f"
+	    git $cmd >> "$f"
 	    if contrib/gcc-changelog/git_email.py "$f" >/dev/null 2>&1; then
 		# Existing commit message is still OK for amended commit.
-		rm $f
+		rm "$f"
 		exit 0
 	    fi
-	    rm $f
+	    rm "$f"
 	fi
     else
 	cmd="diff --cached"
@@ -72,7 +72,7 @@ fi
 
 # Save diff to a file if requested.
 DIFF_FILE=$(git config gcc-config.diff-file)
-if ! [ -z "$DIFF_FILE" ]; then
+if [ -n "$DIFF_FILE" ]; then
     tee="tee $DIFF_FILE"
 else
     tee="cat"