Re: [PATCH v4 04/10] kunit: string-stream: Add option to make all lines end with newline

David Gow
2023-08-15T09:18:53Z

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On Mon, 14 Aug 2023 at 21:23, Richard Fitzgerald
<rf@opensource.cirrus.com> wrote:
>
> Add an optional feature to string_stream that will append a newline to
> any added string that does not already end with a newline. The purpose
> of this is so that string_stream can be used to collect log lines.
>
> This is enabled/disabled by calling string_stream_set_append_newlines().
>
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
> ---

Looks good. I don't mind the extra 'wasted' byte if a message already
ends in a newline.

Reviewed-by: David Gow <davidgow@google.com>

> lib/kunit/string-stream.c | 28 +++++++++++++++++++++-------
> lib/kunit/string-stream.h | 7 +++++++
> 2 files changed, 28 insertions(+), 7 deletions(-)
>
> diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c
> index ed24d86af9f5..1dcf6513b692 100644
> --- a/lib/kunit/string-stream.c
> +++ b/lib/kunit/string-stream.c
> @@ -44,32 +44,46 @@ int string_stream_vadd(struct string_stream *stream,
> va_list args)
> {
> struct string_stream_fragment *frag_container;
> - int len;
> + int buf_len, result_len;
> va_list args_for_counting;
>
> /* Make a copy because `vsnprintf` could change it */
> va_copy(args_for_counting, args);
>
> /* Evaluate length of formatted string */
> - len = vsnprintf(NULL, 0, fmt, args_for_counting);
> + buf_len = vsnprintf(NULL, 0, fmt, args_for_counting);
>
> va_end(args_for_counting);
>
> - if (len == 0)
> + if (buf_len == 0)
> return 0;
>
> + /* Reserve one extra for possible appended newline. */
> + if (stream->append_newlines)
> + buf_len++;
> +
> /* Need space for null byte. */
> - len++;
> + buf_len++;
>
> frag_container = alloc_string_stream_fragment(stream->test,
> - len,
> + buf_len,
> stream->gfp);
> if (IS_ERR(frag_container))
> return PTR_ERR(frag_container);
>
> - len = vsnprintf(frag_container->fragment, len, fmt, args);
> + if (stream->append_newlines) {
> + /* Don't include reserved newline byte in writeable length. */
> + result_len = vsnprintf(frag_container->fragment, buf_len - 1, fmt, args);
> +
> + /* Append newline if necessary. */
> + if (frag_container->fragment[result_len - 1] != '\n')
> + result_len = strlcat(frag_container->fragment, "\n", buf_len);
> + } else {
> + result_len = vsnprintf(frag_container->fragment, buf_len, fmt, args);
> + }
> +
> spin_lock(&stream->lock);
> - stream->length += len;
> + stream->length += result_len;
> list_add_tail(&frag_container->node, &stream->fragments);
> spin_unlock(&stream->lock);
>
> diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h
> index b669f9a75a94..048930bf97f0 100644
> --- a/lib/kunit/string-stream.h
> +++ b/lib/kunit/string-stream.h
> @@ -25,6 +25,7 @@ struct string_stream {
> spinlock_t lock;
> struct kunit *test;
> gfp_t gfp;
> + bool append_newlines;
> };
>
> struct kunit;
> @@ -47,4 +48,10 @@ bool string_stream_is_empty(struct string_stream *stream);
>
> void string_stream_destroy(struct string_stream *stream);
>
> +static inline void string_stream_set_append_newlines(struct string_stream *stream,
> + bool append_newlines)
> +{
> + stream->append_newlines = append_newlines;
> +}
> +
> #endif /* _KUNIT_STRING_STREAM_H */
> --
> 2.30.2
>

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