[PATCH 2/3] commit: Show author if different from committer

["Santi Béjar" <sbejar@gmail.com>]

That would help reassure anybody while committing other's changes.

Signed-off-by: Santi Béjar <sbejar@gmail.com>
---
 builtin-commit.c  |   23 ++++++++++++++++++++---
 t/t7502-commit.sh |   10 ++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/builtin-commit.c b/builtin-commit.c
index a37d8c3..c51c70f 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -47,6 +47,7 @@ static enum {
 
 static char *logfile, *force_author, *template_file;
 static char *edit_message, *use_message;
+static char *author_name, *author_email, *author_date;
 static int all, edit_flag, also, interactive, only, amend, signoff;
 static int quiet, verbose, untracked_files, no_verify, allow_empty;
 /*
@@ -395,7 +396,7 @@ static int is_a_merge(const unsigned char *sha1)
 
 static const char sign_off_header[] = "Signed-off-by: ";
 
-static void determine_author_info(struct strbuf *sb)
+static void determine_author_info()
 {
 	char *name, *email, *date;
 
@@ -431,7 +432,9 @@ static void determine_author_info(struct strbuf *sb)
 		email = xstrndup(lb + 2, rb - (lb + 2));
 	}
 
-	strbuf_addf(sb, "author %s\n", fmt_ident(name, email, date, IDENT_ERROR_ON_NO_NAME));
+	author_name = name;
+	author_email = email;
+	author_date = date;
 }
 
 static int prepare_to_commit(const char *index_file, const char *prefix)
@@ -443,6 +446,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix)
 	FILE *fp;
 	const char *hook_arg1 = NULL;
 	const char *hook_arg2 = NULL;
+	const char *author_ident;
+	const char *committer_ident;
 
 	if (!no_verify && run_hook(index_file, "pre-commit", NULL))
 		return 0;
@@ -522,6 +527,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix)
 
 	strbuf_release(&sb);
 
+	determine_author_info();
+
 	if (use_editor) {
 		if (in_merge)
 			fprintf(fp,
@@ -545,6 +552,15 @@ static int prepare_to_commit(const char *index_file, const char *prefix)
 		if (only_include_assumed)
 			fprintf(fp, "# %s\n", only_include_assumed);
 
+		author_ident = xstrdup(fmt_name(author_name, author_email));
+		committer_ident =
+			xstrdup(fmt_name(getenv("GIT_COMMITTER_NAME"),
+					 getenv("GIT_COMMITTER_EMAIL")));
+		if (strcmp(author_ident, committer_ident))
+			fprintf(fp,
+				"# Author:    %s\n",
+				fmt_name(author_name, author_email));
+
 		saved_color_setting = wt_status_use_color;
 		wt_status_use_color = 0;
 		commitable = run_status(fp, index_file, prefix, 1);
@@ -920,7 +936,8 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		strbuf_addf(&sb, "parent %s\n", sha1_to_hex(head_sha1));
 	}
 
-	determine_author_info(&sb);
+	strbuf_addf(&sb, "author %s\n",
+		    fmt_ident(author_name, author_email, author_date, IDENT_ERROR_ON_NO_NAME));
 	strbuf_addf(&sb, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
 	if (!is_encoding_utf8(git_commit_encoding))
 		strbuf_addf(&sb, "encoding %s\n", git_commit_encoding);
diff --git a/t/t7502-commit.sh b/t/t7502-commit.sh
index 284c941..95acf4c 100755
--- a/t/t7502-commit.sh
+++ b/t/t7502-commit.sh
@@ -154,6 +154,16 @@ test_expect_success 'cleanup commit messages (strip,-F,-e)' '
 
 '
 
+echo "# Author:    $GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL>" >> expect
+
+test_expect_success 'author different from committer' '
+
+	echo >>negative &&
+	git commit -e -m "sample"
+	head -n 5 .git/COMMIT_EDITMSG >actual &&
+	test_cmp expect actual
+'
+
 pwd=`pwd`
 cat >> .git/FAKE_EDITOR << EOF
 #! /bin/sh
-- 
1.5.5.1.148.g37726