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}
156