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From:   Richard Fitzgerald <rf@opensource.cirrus.com>
To:     <brendan.higgins@linux.dev>, <davidgow@google.com>,
        <rmoar@google.com>
CC:     <linux-kselftest@vger.kernel.org>, <kunit-dev@googlegroups.com>,
        <linux-kernel@vger.kernel.org>, <patches@opensource.cirrus.com>,
        Richard Fitzgerald <rf@opensource.cirrus.com>
Subject: [PATCH v4 02/10] kunit: string-stream: Don't create a fragment for empty strings
Date:   Mon, 14 Aug 2023 14:23:01 +0100
Message-ID: <20230814132309.32641-3-rf@opensource.cirrus.com>
In-Reply-To: <20230814132309.32641-1-rf@opensource.cirrus.com>
References: <20230814132309.32641-1-rf@opensource.cirrus.com>
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If the result of the formatted string is an empty string just return
instead of creating an empty fragment.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
 lib/kunit/string-stream.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c
index cc32743c1171..ed24d86af9f5 100644
--- a/lib/kunit/string-stream.c
+++ b/lib/kunit/string-stream.c
@@ -50,11 +50,17 @@ int string_stream_vadd(struct string_stream *stream,
 	/* Make a copy because `vsnprintf` could change it */
 	va_copy(args_for_counting, args);
 
-	/* Need space for null byte. */
-	len = vsnprintf(NULL, 0, fmt, args_for_counting) + 1;
+	/* Evaluate length of formatted string */
+	len = vsnprintf(NULL, 0, fmt, args_for_counting);
 
 	va_end(args_for_counting);
 
+	if (len == 0)
+		return 0;
+
+	/* Need space for null byte. */
+	len++;
+
 	frag_container = alloc_string_stream_fragment(stream->test,
 						      len,
 						      stream->gfp);
-- 
2.30.2