[PATCH v1 3/3] kunit: fix bug of extra newline characters in debugfs logs

[Rae Moar]

Fix bug of the extra newline characters in debugfs logs. When a
line is added to debugfs with a newline character at the end,
an extra line appears in the debugfs log. Remove these extra lines.

Add kunit_log_newline_test to provide test coverage for this issue.
(Also, move kunit_log_test above suite definition to remove the
unnecessary declaration prior to the suite definition)

Signed-off-by: Rae Moar <rmoar@xxxxxxxxxx>
---
 lib/kunit/kunit-test.c | 36 ++++++++++++++++++++++++------------
 lib/kunit/test.c       |  9 ++++++++-
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c
index 4df0335d0d06..e9114a466f1e 100644
--- a/lib/kunit/kunit-test.c
+++ b/lib/kunit/kunit-test.c
@@ -443,18 +443,6 @@ static struct kunit_suite kunit_resource_test_suite = {
 	.test_cases = kunit_resource_test_cases,
 };
 
-static void kunit_log_test(struct kunit *test);
-
-static struct kunit_case kunit_log_test_cases[] = {
-	KUNIT_CASE(kunit_log_test),
-	{}
-};
-
-static struct kunit_suite kunit_log_test_suite = {
-	.name = "kunit-log-test",
-	.test_cases = kunit_log_test_cases,
-};
-
 static void kunit_log_test(struct kunit *test)
 {
 	struct kunit_suite suite;
@@ -481,6 +469,30 @@ static void kunit_log_test(struct kunit *test)
 #endif
 }
 
+static void kunit_log_newline_test(struct kunit *test)
+{
+#ifdef CONFIG_KUNIT_DEBUGFS
+	kunit_info(test, "extra newline\n");
+
+	KUNIT_ASSERT_NOT_NULL_MSG(test, strstr(test->log, "extra newline\n"),
+		"Missing log line, full log:\n%s", test->log);
+	KUNIT_EXPECT_NULL(test, strstr(test->log, "extra newline\n\n"));
+#else
+	kunit_skip(test, "only useful when debugfs is enabled");
+#endif
+}
+
+static struct kunit_case kunit_log_test_cases[] = {
+	KUNIT_CASE(kunit_log_test),
+	KUNIT_CASE(kunit_log_newline_test),
+	{}
+};
+
+static struct kunit_suite kunit_log_test_suite = {
+	.name = "kunit-log-test",
+	.test_cases = kunit_log_test_cases,
+};
+
 static void kunit_status_set_failure_test(struct kunit *test)
 {
 	struct kunit fake;
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 27763f0b420c..76d9c31943bf 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -117,6 +117,7 @@ void kunit_log_append(char *log, const char *fmt, ...)
 	char line[KUNIT_LOG_SIZE];
 	va_list args;
 	int len_left;
+	int line_len;
 
 	if (!log)
 		return;
@@ -125,10 +126,16 @@ void kunit_log_append(char *log, const char *fmt, ...)
 	if (len_left <= 0)
 		return;
 
+	// Evaluate the length of the line with arguments
 	va_start(args, fmt);
-	vsnprintf(line, sizeof(line), fmt, args);
+	line_len = vsnprintf(line, sizeof(line), fmt, args);
 	va_end(args);
 
+	// If line has two newline characters, do not print
+	// second newline character
+	if (fmt[strlen(fmt) - 2] == '\n')
+		line[line_len - 1] = '\0';
+
 	strncat(log, line, len_left);
 }
 EXPORT_SYMBOL_GPL(kunit_log_append);
-- 
2.39.1.456.gfc5497dd1b-goog