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 
alloc_string_stream_fragment(struct kunit * test,int len,gfp_t gfp)16 static 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 
string_stream_fragment_destroy(struct kunit * test,struct string_stream_fragment * frag)34 static 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 
string_stream_vadd(struct string_stream * stream,const char * fmt,va_list args)42 int 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 
string_stream_add(struct string_stream * stream,const char * fmt,...)73 int 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 
string_stream_clear(struct string_stream * stream)85 static 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 
string_stream_get_string(struct string_stream * stream)100 char *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 
string_stream_append(struct string_stream * stream,struct string_stream * other)118 int 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 
string_stream_is_empty(struct string_stream * stream)131 bool string_stream_is_empty(struct string_stream *stream)
132 {
133 	return list_empty(&stream->fragments);
134 }
135 
136 struct string_stream_alloc_context {
137 	struct kunit *test;
138 	gfp_t gfp;
139 };
140 
alloc_string_stream(struct kunit * test,gfp_t gfp)141 struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
142 {
143 	struct string_stream *stream;
144 
145 	stream = kunit_kzalloc(test, sizeof(*stream), gfp);
146 	if (!stream)
147 		return ERR_PTR(-ENOMEM);
148 
149 	stream->gfp = gfp;
150 	stream->test = test;
151 	INIT_LIST_HEAD(&stream->fragments);
152 	spin_lock_init(&stream->lock);
153 
154 	return stream;
155 }
156 
string_stream_destroy(struct string_stream * stream)157 void string_stream_destroy(struct string_stream *stream)
158 {
159 	string_stream_clear(stream);
160 }
161