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/static_stub.h>
10#include <kunit/test.h>
11#include <linux/list.h>
12#include <linux/slab.h>
13
14#include "string-stream.h"
15
16
17static struct string_stream_fragment *alloc_string_stream_fragment(int len, gfp_t gfp)
18{
19	struct string_stream_fragment *frag;
20
21	frag = kzalloc(sizeof(*frag), gfp);
22	if (!frag)
23		return ERR_PTR(-ENOMEM);
24
25	frag->fragment = kmalloc(len, gfp);
26	if (!frag->fragment) {
27		kfree(frag);
28		return ERR_PTR(-ENOMEM);
29	}
30
31	return frag;
32}
33
34static void string_stream_fragment_destroy(struct string_stream_fragment *frag)
35{
36	list_del(&frag->node);
37	kfree(frag->fragment);
38	kfree(frag);
39}
40
41int string_stream_vadd(struct string_stream *stream,
42		       const char *fmt,
43		       va_list args)
44{
45	struct string_stream_fragment *frag_container;
46	int buf_len, result_len;
47	va_list args_for_counting;
48
49	/* Make a copy because `vsnprintf` could change it */
50	va_copy(args_for_counting, args);
51
52	/* Evaluate length of formatted string */
53	buf_len = vsnprintf(NULL, 0, fmt, args_for_counting);
54
55	va_end(args_for_counting);
56
57	if (buf_len == 0)
58		return 0;
59
60	/* Reserve one extra for possible appended newline. */
61	if (stream->append_newlines)
62		buf_len++;
63
64	/* Need space for null byte. */
65	buf_len++;
66
67	frag_container = alloc_string_stream_fragment(buf_len, stream->gfp);
68	if (IS_ERR(frag_container))
69		return PTR_ERR(frag_container);
70
71	if (stream->append_newlines) {
72		/* Don't include reserved newline byte in writeable length. */
73		result_len = vsnprintf(frag_container->fragment, buf_len - 1, fmt, args);
74
75		/* Append newline if necessary. */
76		if (frag_container->fragment[result_len - 1] != '\n')
77			result_len = strlcat(frag_container->fragment, "\n", buf_len);
78	} else {
79		result_len = vsnprintf(frag_container->fragment, buf_len, fmt, args);
80	}
81
82	spin_lock(&stream->lock);
83	stream->length += result_len;
84	list_add_tail(&frag_container->node, &stream->fragments);
85	spin_unlock(&stream->lock);
86
87	return 0;
88}
89
90int string_stream_add(struct string_stream *stream, const char *fmt, ...)
91{
92	va_list args;
93	int result;
94
95	va_start(args, fmt);
96	result = string_stream_vadd(stream, fmt, args);
97	va_end(args);
98
99	return result;
100}
101
102void string_stream_clear(struct string_stream *stream)
103{
104	struct string_stream_fragment *frag_container, *frag_container_safe;
105
106	spin_lock(&stream->lock);
107	list_for_each_entry_safe(frag_container,
108				 frag_container_safe,
109				 &stream->fragments,
110				 node) {
111		string_stream_fragment_destroy(frag_container);
112	}
113	stream->length = 0;
114	spin_unlock(&stream->lock);
115}
116
117char *string_stream_get_string(struct string_stream *stream)
118{
119	struct string_stream_fragment *frag_container;
120	size_t buf_len = stream->length + 1; /* +1 for null byte. */
121	char *buf;
122
123	buf = kzalloc(buf_len, stream->gfp);
124	if (!buf)
125		return NULL;
126
127	spin_lock(&stream->lock);
128	list_for_each_entry(frag_container, &stream->fragments, node)
129		strlcat(buf, frag_container->fragment, buf_len);
130	spin_unlock(&stream->lock);
131
132	return buf;
133}
134
135int string_stream_append(struct string_stream *stream,
136			 struct string_stream *other)
137{
138	const char *other_content;
139	int ret;
140
141	other_content = string_stream_get_string(other);
142
143	if (!other_content)
144		return -ENOMEM;
145
146	ret = string_stream_add(stream, other_content);
147	kfree(other_content);
148
149	return ret;
150}
151
152bool string_stream_is_empty(struct string_stream *stream)
153{
154	return list_empty(&stream->fragments);
155}
156
157struct string_stream *alloc_string_stream(gfp_t gfp)
158{
159	struct string_stream *stream;
160
161	stream = kzalloc(sizeof(*stream), gfp);
162	if (!stream)
163		return ERR_PTR(-ENOMEM);
164
165	stream->gfp = gfp;
166	INIT_LIST_HEAD(&stream->fragments);
167	spin_lock_init(&stream->lock);
168
169	return stream;
170}
171
172void string_stream_destroy(struct string_stream *stream)
173{
174	KUNIT_STATIC_STUB_REDIRECT(string_stream_destroy, stream);
175
176	if (IS_ERR_OR_NULL(stream))
177		return;
178
179	string_stream_clear(stream);
180	kfree(stream);
181}
182
183static void resource_free_string_stream(void *p)
184{
185	struct string_stream *stream = p;
186
187	string_stream_destroy(stream);
188}
189
190struct string_stream *kunit_alloc_string_stream(struct kunit *test, gfp_t gfp)
191{
192	struct string_stream *stream;
193
194	stream = alloc_string_stream(gfp);
195	if (IS_ERR(stream))
196		return stream;
197
198	if (kunit_add_action_or_reset(test, resource_free_string_stream, stream) != 0)
199		return ERR_PTR(-ENOMEM);
200
201	return stream;
202}
203
204void kunit_free_string_stream(struct kunit *test, struct string_stream *stream)
205{
206	kunit_release_action(test, resource_free_string_stream, (void *)stream);
207}
208