xref: /linux/lib/kunit/string-stream.c (revision e7d759f31ca295d589f7420719c311870bb3166f)
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 
17 static 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 
34 static 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 
41 int 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 
90 int 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 
102 void 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 
117 char *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 
135 int 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 
152 bool string_stream_is_empty(struct string_stream *stream)
153 {
154 	return list_empty(&stream->fragments);
155 }
156 
157 struct 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 
172 void 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 
183 static void resource_free_string_stream(void *p)
184 {
185 	struct string_stream *stream = p;
186 
187 	string_stream_destroy(stream);
188 }
189 
190 struct 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 
204 void 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