1 files changed, 155 insertions, 0 deletions
diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c
new file mode 100644
index 0000000000..cc32743c11
--- /dev/null
+++ b/lib/kunit/string-stream.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * C++ stream style string builder used in KUnit for building messages.
+ *
+ * Copyright (C) 2019, Google LLC.
+ * Author: Brendan Higgins <brendanhiggins@google.com>
+ */
+
+#include <kunit/test.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#include "string-stream.h"
+
+
+static struct string_stream_fragment *alloc_string_stream_fragment(
+		struct kunit *test, int len, gfp_t gfp)
+{
+	struct string_stream_fragment *frag;
+
+	frag = kunit_kzalloc(test, sizeof(*frag), gfp);
+	if (!frag)
+		return ERR_PTR(-ENOMEM);
+
+	frag->fragment = kunit_kmalloc(test, len, gfp);
+	if (!frag->fragment) {
+		kunit_kfree(test, frag);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	return frag;
+}
+
+static void string_stream_fragment_destroy(struct kunit *test,
+					   struct string_stream_fragment *frag)
+{
+	list_del(&frag->node);
+	kunit_kfree(test, frag->fragment);
+	kunit_kfree(test, frag);
+}
+
+int string_stream_vadd(struct string_stream *stream,
+		       const char *fmt,
+		       va_list args)
+{
+	struct string_stream_fragment *frag_container;
+	int len;
+	va_list args_for_counting;
+
+	/* 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;
+
+	va_end(args_for_counting);
+
+	frag_container = alloc_string_stream_fragment(stream->test,
+						      len,
+						      stream->gfp);
+	if (IS_ERR(frag_container))
+		return PTR_ERR(frag_container);
+
+	len = vsnprintf(frag_container->fragment, len, fmt, args);
+	spin_lock(&stream->lock);
+	stream->length += len;
+	list_add_tail(&frag_container->node, &stream->fragments);
+	spin_unlock(&stream->lock);
+
+	return 0;
+}
+
+int string_stream_add(struct string_stream *stream, const char *fmt, ...)
+{
+	va_list args;
+	int result;
+
+	va_start(args, fmt);
+	result = string_stream_vadd(stream, fmt, args);
+	va_end(args);
+
+	return result;
+}
+
+static void string_stream_clear(struct string_stream *stream)
+{
+	struct string_stream_fragment *frag_container, *frag_container_safe;
+
+	spin_lock(&stream->lock);
+	list_for_each_entry_safe(frag_container,
+				 frag_container_safe,
+				 &stream->fragments,
+				 node) {
+		string_stream_fragment_destroy(stream->test, frag_container);
+	}
+	stream->length = 0;
+	spin_unlock(&stream->lock);
+}
+
+char *string_stream_get_string(struct string_stream *stream)
+{
+	struct string_stream_fragment *frag_container;
+	size_t buf_len = stream->length + 1; /* +1 for null byte. */
+	char *buf;
+
+	buf = kunit_kzalloc(stream->test, buf_len, stream->gfp);
+	if (!buf)
+		return NULL;
+
+	spin_lock(&stream->lock);
+	list_for_each_entry(frag_container, &stream->fragments, node)
+		strlcat(buf, frag_container->fragment, buf_len);
+	spin_unlock(&stream->lock);
+
+	return buf;
+}
+
+int string_stream_append(struct string_stream *stream,
+			 struct string_stream *other)
+{
+	const char *other_content;
+
+	other_content = string_stream_get_string(other);
+
+	if (!other_content)
+		return -ENOMEM;
+
+	return string_stream_add(stream, other_content);
+}
+
+bool string_stream_is_empty(struct string_stream *stream)
+{
+	return list_empty(&stream->fragments);
+}
+
+struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
+{
+	struct string_stream *stream;
+
+	stream = kunit_kzalloc(test, sizeof(*stream), gfp);
+	if (!stream)
+		return ERR_PTR(-ENOMEM);
+
+	stream->gfp = gfp;
+	stream->test = test;
+	INIT_LIST_HEAD(&stream->fragments);
+	spin_lock_init(&stream->lock);
+
+	return stream;
+}
+
+void string_stream_destroy(struct string_stream *stream)
+{
+	string_stream_clear(stream);
+}