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
 15struct string_stream_fragment_alloc_context {
 16	struct kunit *test;
 17	int len;
 18	gfp_t gfp;
 19};
 20
 21static int string_stream_fragment_init(struct kunit_resource *res,
 22				       void *context)
 23{
 24	struct string_stream_fragment_alloc_context *ctx = context;
 25	struct string_stream_fragment *frag;
 26
 27	frag = kunit_kzalloc(ctx->test, sizeof(*frag), ctx->gfp);
 28	if (!frag)
 29		return -ENOMEM;
 30
 31	frag->test = ctx->test;
 32	frag->fragment = kunit_kmalloc(ctx->test, ctx->len, ctx->gfp);
 33	if (!frag->fragment)
 34		return -ENOMEM;
 35
 36	res->data = frag;
 37
 38	return 0;
 39}
 40
 41static void string_stream_fragment_free(struct kunit_resource *res)
 42{
 43	struct string_stream_fragment *frag = res->data;
 44
 45	list_del(&frag->node);
 46	kunit_kfree(frag->test, frag->fragment);
 47	kunit_kfree(frag->test, frag);
 48}
 49
 50static struct string_stream_fragment *alloc_string_stream_fragment(
 51		struct kunit *test, int len, gfp_t gfp)
 52{
 53	struct string_stream_fragment_alloc_context context = {
 54		.test = test,
 55		.len = len,
 56		.gfp = gfp
 57	};
 58
 59	return kunit_alloc_resource(test,
 60				    string_stream_fragment_init,
 61				    string_stream_fragment_free,
 62				    gfp,
 63				    &context);
 64}
 65
 66static int string_stream_fragment_destroy(struct string_stream_fragment *frag)
 67{
 68	return kunit_destroy_resource(frag->test,
 69				      kunit_resource_instance_match,
 70				      frag);
 71}
 72
 73int string_stream_vadd(struct string_stream *stream,
 74		       const char *fmt,
 75		       va_list args)
 76{
 77	struct string_stream_fragment *frag_container;
 78	int len;
 79	va_list args_for_counting;
 80
 81	/* Make a copy because `vsnprintf` could change it */
 82	va_copy(args_for_counting, args);
 83
 84	/* Need space for null byte. */
 85	len = vsnprintf(NULL, 0, fmt, args_for_counting) + 1;
 86
 87	va_end(args_for_counting);
 88
 89	frag_container = alloc_string_stream_fragment(stream->test,
 90						      len,
 91						      stream->gfp);
 92	if (!frag_container)
 93		return -ENOMEM;
 94
 95	len = vsnprintf(frag_container->fragment, len, fmt, args);
 96	spin_lock(&stream->lock);
 97	stream->length += len;
 98	list_add_tail(&frag_container->node, &stream->fragments);
 99	spin_unlock(&stream->lock);
100
101	return 0;
102}
103
104int string_stream_add(struct string_stream *stream, const char *fmt, ...)
105{
106	va_list args;
107	int result;
108
109	va_start(args, fmt);
110	result = string_stream_vadd(stream, fmt, args);
111	va_end(args);
112
113	return result;
114}
115
116static void string_stream_clear(struct string_stream *stream)
117{
118	struct string_stream_fragment *frag_container, *frag_container_safe;
119
120	spin_lock(&stream->lock);
121	list_for_each_entry_safe(frag_container,
122				 frag_container_safe,
123				 &stream->fragments,
124				 node) {
125		string_stream_fragment_destroy(frag_container);
126	}
127	stream->length = 0;
128	spin_unlock(&stream->lock);
129}
130
131char *string_stream_get_string(struct string_stream *stream)
132{
133	struct string_stream_fragment *frag_container;
134	size_t buf_len = stream->length + 1; /* +1 for null byte. */
135	char *buf;
136
137	buf = kunit_kzalloc(stream->test, buf_len, stream->gfp);
138	if (!buf)
139		return NULL;
140
141	spin_lock(&stream->lock);
142	list_for_each_entry(frag_container, &stream->fragments, node)
143		strlcat(buf, frag_container->fragment, buf_len);
144	spin_unlock(&stream->lock);
145
146	return buf;
147}
148
149int string_stream_append(struct string_stream *stream,
150			 struct string_stream *other)
151{
152	const char *other_content;
153
154	other_content = string_stream_get_string(other);
155
156	if (!other_content)
157		return -ENOMEM;
158
159	return string_stream_add(stream, other_content);
160}
161
162bool string_stream_is_empty(struct string_stream *stream)
163{
164	return list_empty(&stream->fragments);
165}
166
167struct string_stream_alloc_context {
168	struct kunit *test;
169	gfp_t gfp;
170};
171
172static int string_stream_init(struct kunit_resource *res, void *context)
173{
174	struct string_stream *stream;
175	struct string_stream_alloc_context *ctx = context;
176
177	stream = kunit_kzalloc(ctx->test, sizeof(*stream), ctx->gfp);
178	if (!stream)
179		return -ENOMEM;
180
181	res->data = stream;
182	stream->gfp = ctx->gfp;
183	stream->test = ctx->test;
184	INIT_LIST_HEAD(&stream->fragments);
185	spin_lock_init(&stream->lock);
186
187	return 0;
188}
189
190static void string_stream_free(struct kunit_resource *res)
191{
192	struct string_stream *stream = res->data;
193
194	string_stream_clear(stream);
195}
196
197struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
198{
199	struct string_stream_alloc_context context = {
200		.test = test,
201		.gfp = gfp
202	};
203
204	return kunit_alloc_resource(test,
205				    string_stream_init,
206				    string_stream_free,
207				    gfp,
208				    &context);
209}
210
211int string_stream_destroy(struct string_stream *stream)
212{
213	return kunit_destroy_resource(stream->test,
214				      kunit_resource_instance_match,
215				      stream);
216}