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}