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(size: sizeof(*frag), flags: gfp);
22 if (!frag)
23 return ERR_PTR(error: -ENOMEM);
24
25 frag->fragment = kmalloc(size: len, flags: gfp);
26 if (!frag->fragment) {
27 kfree(objp: frag);
28 return ERR_PTR(error: -ENOMEM);
29 }
30
31 return frag;
32}
33
34static void string_stream_fragment_destroy(struct string_stream_fragment *frag)
35{
36 list_del(entry: &frag->node);
37 kfree(objp: frag->fragment);
38 kfree(objp: 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, size: 0, fmt, args: 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(len: buf_len, gfp: stream->gfp);
68 if (IS_ERR(ptr: frag_container))
69 return PTR_ERR(ptr: frag_container);
70
71 if (stream->append_newlines) {
72 /* Don't include reserved newline byte in writeable length. */
73 result_len = vsnprintf(buf: frag_container->fragment, size: buf_len - 1, fmt, args);
74
75 /* Append newline if necessary. */
76 if (frag_container->fragment[result_len - 1] != '\n')
77 result_len = strlcat(p: frag_container->fragment, q: "\n", avail: buf_len);
78 } else {
79 result_len = vsnprintf(buf: frag_container->fragment, size: buf_len, fmt, args);
80 }
81
82 spin_lock(lock: &stream->lock);
83 stream->length += result_len;
84 list_add_tail(new: &frag_container->node, head: &stream->fragments);
85 spin_unlock(lock: &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(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: frag_container);
112 }
113 stream->length = 0;
114 spin_unlock(lock: &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(size: buf_len, flags: stream->gfp);
124 if (!buf)
125 return NULL;
126
127 spin_lock(lock: &stream->lock);
128 list_for_each_entry(frag_container, &stream->fragments, node)
129 strlcat(p: buf, q: frag_container->fragment, avail: buf_len);
130 spin_unlock(lock: &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(stream: other);
142
143 if (!other_content)
144 return -ENOMEM;
145
146 ret = string_stream_add(stream, fmt: other_content);
147 kfree(objp: other_content);
148
149 return ret;
150}
151
152bool string_stream_is_empty(struct string_stream *stream)
153{
154 return list_empty(head: &stream->fragments);
155}
156
157struct string_stream *alloc_string_stream(gfp_t gfp)
158{
159 struct string_stream *stream;
160
161 stream = kzalloc(size: sizeof(*stream), flags: gfp);
162 if (!stream)
163 return ERR_PTR(error: -ENOMEM);
164
165 stream->gfp = gfp;
166 INIT_LIST_HEAD(list: &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(ptr: stream))
177 return;
178
179 string_stream_clear(stream);
180 kfree(objp: 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(ptr: stream))
196 return stream;
197
198 if (kunit_add_action_or_reset(test, action: resource_free_string_stream, ctx: stream) != 0)
199 return ERR_PTR(error: -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, action: resource_free_string_stream, ctx: (void *)stream);
207}
208

source code of linux/lib/kunit/string-stream.c