1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
|
/* Test if fwrite returns consistent values on partial writes.
Copyright (C) 2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
/* stdio.h provides BUFSIZ, which is the size of fwrite's internal buffer. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <support/check.h>
#include <support/fuse.h>
#include <support/support.h>
#include <support/xstdio.h>
#include <support/temp_file.h>
/* Length of the buffer in bytes. */
#define INBUF_SIZE (BUFSIZ)
/* Amount of bytes written to fwrite's internal cache that trigger a
flush. */
#define CACHE_THRESHOLD (BUFSIZ / 2)
#define ITERATIONS 1000
/* Maximum number of bytes written during a partial write. */
#define PARTIAL_BYTES 4
#define EXPECT_EVENT(opcode, state, expected_state) \
{ \
if (state != expected_state) \
{ \
char *s = support_fuse_opcode (opcode); \
FAIL ("unexpected event %s at state %d", s, state); \
free (s); \
} \
}
/* The goal of this test is to check that file position of a file stream is
correctly updated when write () returns a partial write.
The file system simulates pseudorandom partial writes while the test is
running.
Meanwhile the main thread calls fwrite () with a large object first and
small objects later. The usage of a large enough object ensures that
fwrite's internal cache is full enough, without triggering a write to file.
Subsequent calls to fwrite are guaranteed to trigger a write to file. */
static void
fuse_thread (struct support_fuse *f, void *closure)
{
struct fuse_in_header *inh;
int state = 0;
while ((inh = support_fuse_next (f)) != NULL)
{
{
char *opcode = support_fuse_opcode (inh->opcode);
printf ("info: (T) event %s(%llu) len=%u nodeid=%llu\n",
opcode, (unsigned long long int) inh->unique, inh->len,
(unsigned long long int) inh->nodeid);
free (opcode);
}
/* Handle mountpoint and basic directory operation for the root (1). */
if (support_fuse_handle_mountpoint (f)
|| (inh->nodeid == 1 && support_fuse_handle_directory (f)))
continue;
switch (inh->opcode)
{
case FUSE_LOOKUP:
EXPECT_EVENT (inh->nodeid, state, 0);
state++;
support_fuse_reply_error (f, ENOENT);
break;
case FUSE_CREATE:
EXPECT_EVENT (inh->nodeid, state, 1);
state++;
struct fuse_entry_out *entry;
struct fuse_open_out *open;
support_fuse_prepare_create (f, 2, &entry, &open);
entry->attr.mode = S_IFREG | 0600;
support_fuse_reply_prepared (f);
break;
case FUSE_GETXATTR:
/* We don't need to support extended attributes in this test. */
support_fuse_reply_error (f, ENOSYS);
break;
case FUSE_GETATTR:
/* Happens after open. */
if (inh->nodeid == 2)
{
struct fuse_attr_out *out = support_fuse_prepare_attr (f);
out->attr.mode = S_IFREG | 0600;
out->attr.size = 0;
support_fuse_reply_prepared (f);
}
else
support_fuse_reply_error (f, ENOENT);
break;
case FUSE_WRITE:
if (inh->nodeid == 2)
{
struct fuse_write_out out;
if (state > 1 && state < ITERATIONS + 2)
{
/* The 2nd and subsequent calls to fwrite () trigger a
flush of fwrite's internal cache. Simulate a partial
write of up to PARTIAL_BYTES bytes. */
out.padding = 0;
out.size = 1 + rand () % PARTIAL_BYTES,
state++;
support_fuse_reply (f, &out, sizeof (out));
}
else if (state >= ITERATIONS + 2)
{
/* This request is expected to come from fflush (). Copy
all the data successfully. This may be executed more
than once. */
struct fuse_write_in *p = support_fuse_cast (WRITE, inh);
out.padding = 0;
out.size = p->size,
state++;
support_fuse_reply (f, &out, sizeof (out));
}
else
support_fuse_reply_error (f, EIO);
}
else
support_fuse_reply_error (f, EIO);
break;
case FUSE_FLUSH:
case FUSE_RELEASE:
TEST_COMPARE (inh->nodeid, 2);
support_fuse_reply_empty (f);
break;
default:
FAIL ("unexpected event %s", support_fuse_opcode (inh->opcode));
support_fuse_reply_error (f, EIO);
}
}
}
static int
do_test (void)
{
char *in;
int i;
size_t written;
_Static_assert (CACHE_THRESHOLD <= INBUF_SIZE,
"the input buffer must be larger than the cache threshold");
/* Avoid filling up fwrite's cache. */
_Static_assert (CACHE_THRESHOLD - 1 + PARTIAL_BYTES * ITERATIONS <= BUFSIZ,
"fwrite's cache must fit all data written");
support_fuse_init ();
struct support_fuse *fs = support_fuse_mount (fuse_thread, NULL);
/* Create and open a temporary file in the fuse mount point. */
char *fname = xasprintf ("%s/%sXXXXXX", support_fuse_mountpoint (fs),
"tst-fwrite-fuse");
int fd = mkstemp (fname);
TEST_VERIFY_EXIT (fd != -1);
FILE *f = fdopen (fd, "w");
TEST_VERIFY_EXIT (f != NULL);
/* Allocate an input array that will be written to the temporary file. */
in = xmalloc (INBUF_SIZE);
for (i = 0; i < INBUF_SIZE; i++)
in[i] = i % 0xff;
/* Ensure the file position indicator is at the beginning of the stream. */
TEST_COMPARE (ftell (f), 0);
/* Try to fill as most data to the cache of the file stream as possible
with a single large object.
All data is expected to be written to the cache.
No errors are expected from this. */
TEST_COMPARE (fwrite (in, CACHE_THRESHOLD - 1, 1, f), 1);
TEST_COMPARE (ferror (f), 0);
written = CACHE_THRESHOLD - 1;
/* Ensure the file position indicator advanced correctly. */
TEST_COMPARE (ftell (f), written);
for (i = 0; i < ITERATIONS; i++)
{
/* Write an extra object of size PARTIAL_BYTES that triggers a write to
disk. Our FS will write at most PARTIAL_BYTES bytes to the file
instead of all the data. By writting PARTIAL_BYTES, we guarantee
the amount of data in the cache will never decrease below
CACHE_THRESHOLD.
No errors are expected. */
TEST_COMPARE (fwrite (in, PARTIAL_BYTES, 1, f), 1);
TEST_COMPARE (ferror (f), 0);
written += PARTIAL_BYTES;
/* Ensure the file position indicator advanced correctly. */
TEST_COMPARE (ftell (f), written);
}
/* Flush the rest of the data. */
TEST_COMPARE (fflush (f), 0);
TEST_COMPARE (ferror (f), 0);
/* Ensure the file position indicator was not modified. */
TEST_COMPARE (ftell (f), written);
/* In case an unexpected error happened, clear it before exiting. */
if (ferror (f))
clearerr (f);
xfclose (f);
free (fname);
free (in);
support_fuse_unmount (fs);
return 0;
}
#include <support/test-driver.c>
|
