lib/kunit/string-stream.c

   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 }