Re: [PATCH v2] interpret-trailers: handle message without trailing newline

From: Phillip Wood <hidden>
Date: 2024-09-06 09:07:07
Subsystem: the rest · Maintainer: Linus Torvalds

Hi Brian

On 06/09/2024 05:08, Brian Lyles wrote:

When git-interpret-trailers is used to add a trailer to a message that
does not end in a trailing newline, the new trailer is added on the line
immediately following the message instead of as a trailer block
separated from the message by a blank line.

For example, if a message's text was exactly "The subject" with no
trailing newline present, `git interpret-trailers --trailer
my-trailer=true` will result in the following malformed commit message:

     The subject
     my-trailer: true

While it is generally expected that a commit message should end with a
newline character, git-interpret-trailers should not be returning an
invalid message in this case.

Detect when a message exists but does not end with a newline character,
and add an extra newline before appending the new trailer.

Thanks for the comprehensive commit message. If the problem only affects
"git interpret-trailers" I wonder if it would be simpler to do

diff --git a/builtin/interpret-trailers.c b/builtin/interpret-trailers.c
index 1d969494cf..e6f22459f1 100644
--- a/builtin/interpret-trailers.c
+++ b/builtin/interpret-trailers.c

@@ -132,6 +132,7 @@ static void read_input_file(struct strbuf *sb, const char *file)
                  if (strbuf_read(sb, fileno(stdin), 0) < 0)
                          die_errno(_("could not read from stdin"));
          }
+        strbuf_complete_line(sb);
  }
  
  static void interpret_trailers(const struct process_trailer_options *opts,

So that we feed the trailer machinery a message with a trailing new line.
Thanks for adding some tests, I've left one small comment below.

quoted hunk ↗ jump to hunk

diff --git a/builtin/interpret-trailers.c b/builtin/interpret-trailers.c
index 1d969494cf..9d8f94341d 100644
--- a/builtin/interpret-trailers.c
+++ b/builtin/interpret-trailers.c

@@ -153,13 +153,15 @@ static void interpret_trailers(const struct process_trailer_options *opts,

  	info = parse_trailers(opts, sb.buf, &head);

-	/* Print the lines before the trailers */
-	if (!opts->only_trailers)
+	if (!opts->only_trailers) {
+		/* Print the lines before the trailers */
  		fwrite(sb.buf, 1, trailer_block_start(info), outfile);

-	if (!opts->only_trailers && !blank_line_before_trailer_block(info))
-		fprintf(outfile, "\n");
-
+		if (message_without_trailing_newline_before_trailer_block(info))
+			fprintf(outfile, "\n\n");
+		else if (!blank_line_before_trailer_block(info))
+			fprintf(outfile, "\n");
+	}

  	if (!opts->only_input) {
  		LIST_HEAD(config_head);

diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index 3d3e13ccf8..d5303c3f74 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh

@@ -175,6 +175,46 @@ test_expect_success 'with only a title in the message' '
  	test_cmp expected actual
  '

+test_expect_success 'with a bodiless message that lacks a trailing newline after the subject' '
+	cat >expected <<-\EOF &&
+		area: change
+
+		Reviewed-by: Peff
+		Acked-by: Johan
+	EOF
+	printf "area: change" | \

There is no need to add a backslash after the pipe here or in the other tests.

Best Wishes

Phillip

quoted hunk ↗ jump to hunk

+	git interpret-trailers --trailer "Reviewed-by: Peff" \
+		--trailer "Acked-by: Johan" >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'with a bodied message that lacks a trailing newline after the body' '
+	cat >expected <<-\EOF &&
+		area: change
+
+		details about the change.
+
+		Reviewed-by: Peff
+		Acked-by: Johan
+	EOF
+	printf "area: change\n\ndetails about the change." | \
+	git interpret-trailers --trailer "Reviewed-by: Peff" \
+		--trailer "Acked-by: Johan" >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'with a message that lacks a trailing newline after the trailers' '
+	cat >expected <<-\EOF &&
+		area: change
+
+		Reviewed-by: Peff
+		Acked-by: Johan
+	EOF
+	printf "area: change\n\nReviewed-by: Peff" | \
+	git interpret-trailers --trailer "Acked-by: Johan" >actual &&
+	test_cmp expected actual
+'
+
  test_expect_success 'with multiline title in the message' '
  	cat >expected <<-\EOF &&
  		place of

diff --git a/trailer.c b/trailer.c
index 72e5136c73..178adae6ad 100644
--- a/trailer.c
+++ b/trailer.c

@@ -18,6 +18,12 @@ struct trailer_info {
  	 */
  	int blank_line_before_trailer;

+	/*
+	 * True if there is a message before the trailer block and it does not
+	 * end with a trailing newline character.
+	 */
+	int message_without_trailing_newline_before_trailer;
+
  	/*
  	 * Offsets to the trailer block start and end positions in the input
  	 * string. If no trailer block is found, these are both set to the

@@ -946,6 +952,11 @@ static int ends_with_blank_line(const char *buf, size_t len)
  	return is_blank_line(buf + ll);
  }

+static int has_message_without_trailing_newline_char(const char *buf, size_t len)
+{
+	return len > 0 && buf[len - 1] != '\n';
+}
+
  static void unfold_value(struct strbuf *val)
  {
  	struct strbuf out = STRBUF_INIT;

@@ -1017,6 +1028,8 @@ static struct trailer_info *trailer_info_get(const struct process_trailer_option

  	info->blank_line_before_trailer = ends_with_blank_line(str,
  							       trailer_block_start);
+	info->message_without_trailing_newline_before_trailer
+		= has_message_without_trailing_newline_char(str, trailer_block_start);
  	info->trailer_block_start = trailer_block_start;
  	info->trailer_block_end = end_of_log_message;
  	info->trailers = trailer_strings;

@@ -1090,6 +1103,11 @@ int blank_line_before_trailer_block(struct trailer_info *info)
  	return info->blank_line_before_trailer;
  }

+int message_without_trailing_newline_before_trailer_block(struct trailer_info *info)
+{
+	return info->message_without_trailing_newline_before_trailer;
+}
+
  void trailer_info_release(struct trailer_info *info)
  {
  	size_t i;

diff --git a/trailer.h b/trailer.h
index 6eb53df155..81449151c7 100644
--- a/trailer.h
+++ b/trailer.h

@@ -125,6 +125,12 @@ size_t trailer_block_end(struct trailer_info *);
   */
  int blank_line_before_trailer_block(struct trailer_info *);

+/*
+ * Return true if there is a message before the trailer block and it does not
+ * end with a trailing newline character.
+ */
+int message_without_trailing_newline_before_trailer_block(struct trailer_info *);
+
  /*
   * Free trailer_info struct.
   */
--

2.45.2

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