1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * C++ stream style string builder used in KUnit for building messages.
  4 *
  5 * Copyright (C) 2019, Google LLC.
  6 * Author: Brendan Higgins <brendanhiggins@google.com>
  7 */
  8
  9#include <kunit/test.h>
 10#include <linux/list.h>
 11#include <linux/slab.h>
 12
 13#include "string-stream.h"
 14
 15
 16static struct string_stream_fragment *alloc_string_stream_fragment(
 17		struct kunit *test, int len, gfp_t gfp)
 18{
 19	struct string_stream_fragment *frag;
 20
 21	frag = kunit_kzalloc(test, sizeof(*frag), gfp);
 22	if (!frag)
 23		return ERR_PTR(-ENOMEM);
 24
 25	frag->fragment = kunit_kmalloc(test, len, gfp);
 26	if (!frag->fragment) {
 27		kunit_kfree(test, frag);
 28		return ERR_PTR(-ENOMEM);
 29	}
 30
 31	return frag;
 32}
 33
 34static void string_stream_fragment_destroy(struct kunit *test,
 35					   struct string_stream_fragment *frag)
 36{
 37	list_del(&frag->node);
 38	kunit_kfree(test, frag->fragment);
 39	kunit_kfree(test, frag);
 40}
 41
 42int string_stream_vadd(struct string_stream *stream,
 43		       const char *fmt,
 44		       va_list args)
 45{
 46	struct string_stream_fragment *frag_container;
 47	int len;
 48	va_list args_for_counting;
 49
 50	/* Make a copy because `vsnprintf` could change it */
 51	va_copy(args_for_counting, args);
 52
 53	/* Need space for null byte. */
 54	len = vsnprintf(NULL, 0, fmt, args_for_counting) + 1;
 55
 56	va_end(args_for_counting);
 57
 58	frag_container = alloc_string_stream_fragment(stream->test,
 59						      len,
 60						      stream->gfp);
 61	if (IS_ERR(frag_container))
 62		return PTR_ERR(frag_container);
 63
 64	len = vsnprintf(frag_container->fragment, len, fmt, args);
 65	spin_lock(&stream->lock);
 66	stream->length += len;
 67	list_add_tail(&frag_container->node, &stream->fragments);
 68	spin_unlock(&stream->lock);
 69
 70	return 0;
 71}
 72
 73int string_stream_add(struct string_stream *stream, const char *fmt, ...)
 74{
 75	va_list args;
 76	int result;
 77
 78	va_start(args, fmt);
 79	result = string_stream_vadd(stream, fmt, args);
 80	va_end(args);
 81
 82	return result;
 83}
 84
 85static void string_stream_clear(struct string_stream *stream)
 86{
 87	struct string_stream_fragment *frag_container, *frag_container_safe;
 88
 89	spin_lock(&stream->lock);
 90	list_for_each_entry_safe(frag_container,
 91				 frag_container_safe,
 92				 &stream->fragments,
 93				 node) {
 94		string_stream_fragment_destroy(stream->test, frag_container);
 95	}
 96	stream->length = 0;
 97	spin_unlock(&stream->lock);
 98}
 99
100char *string_stream_get_string(struct string_stream *stream)
101{
102	struct string_stream_fragment *frag_container;
103	size_t buf_len = stream->length + 1; /* +1 for null byte. */
104	char *buf;
105
106	buf = kunit_kzalloc(stream->test, buf_len, stream->gfp);
107	if (!buf)
108		return NULL;
109
110	spin_lock(&stream->lock);
111	list_for_each_entry(frag_container, &stream->fragments, node)
112		strlcat(buf, frag_container->fragment, buf_len);
113	spin_unlock(&stream->lock);
114
115	return buf;
116}
117
118int string_stream_append(struct string_stream *stream,
119			 struct string_stream *other)
120{
121	const char *other_content;
122
123	other_content = string_stream_get_string(other);
124
125	if (!other_content)
126		return -ENOMEM;
127
128	return string_stream_add(stream, other_content);
129}
130
131bool string_stream_is_empty(struct string_stream *stream)
132{
133	return list_empty(&stream->fragments);
134}
135
136struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
137{
138	struct string_stream *stream;
139
140	stream = kunit_kzalloc(test, sizeof(*stream), gfp);
141	if (!stream)
142		return ERR_PTR(-ENOMEM);
143
144	stream->gfp = gfp;
145	stream->test = test;
146	INIT_LIST_HEAD(&stream->fragments);
147	spin_lock_init(&stream->lock);
148
149	return stream;
150}
151
152void string_stream_destroy(struct string_stream *stream)
153{
154	string_stream_clear(stream);
155}