about summary refs log tree commit diff
path: root/io/tst-open-tmpfile.c
blob: 666a3a308b0f881d288f2bad5a17d95fb2d3badf (plain) (blame)
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
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
/* Test open and openat with O_TMPFILE.
   Copyright (C) 2016-2023 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/>.  */

/* This test verifies that open and openat work as expected, i.e. they
   create a deleted file with the requested file mode.  */

#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

#include <support/support.h>

#ifdef O_TMPFILE
typedef int (*wrapper_func) (const char *, int, mode_t);

/* Error-checking wrapper for the open function, compatible with the
   wrapper_func type.  */
static int
wrap_open (const char *path, int flags, mode_t mode)
{
  int ret = open (path, flags, mode);
  if (ret < 0)
    {
      printf ("error: open (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
      exit (1);
    }
  return ret;
}

/* Error-checking wrapper for the openat function, compatible with the
   wrapper_func type.  */
static int
wrap_openat (const char *path, int flags, mode_t mode)
{
  int ret = openat (AT_FDCWD, path, flags, mode);
  if (ret < 0)
    {
      printf ("error: openat (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
      exit (1);
    }
  return ret;
}

/* Error-checking wrapper for the open64 function, compatible with the
   wrapper_func type.  */
static int
wrap_open64 (const char *path, int flags, mode_t mode)
{
  int ret = open64 (path, flags, mode);
  if (ret < 0)
    {
      printf ("error: open64 (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
      exit (1);
    }
  return ret;
}

/* Error-checking wrapper for the openat64 function, compatible with the
   wrapper_func type.  */
static int
wrap_openat64 (const char *path, int flags, mode_t mode)
{
  int ret = openat64 (AT_FDCWD, path, flags, mode);
  if (ret < 0)
    {
      printf ("error: openat64 (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
      exit (1);
    }
  return ret;
}

/* Return true if FD is flagged as deleted in /proc/self/fd, false if
   not.  */
static bool
is_file_deteted (int fd)
{
  char *proc_fd_path = xasprintf ("/proc/self/fd/%d", fd);
  char file_path[4096];
  ssize_t file_path_length
    = readlink (proc_fd_path, file_path, sizeof (file_path));
  if (file_path_length < 0)
    {
      printf ("error: readlink (\"%s\"): %m", proc_fd_path);
      free (proc_fd_path);
      exit (1);
    }
  free (proc_fd_path);
  if (file_path_length == sizeof (file_path))
    {
      printf ("error: path in /proc resolves to overlong file name: %.*s\n",
              (int) file_path_length, file_path);
      exit (1);
    }
  const char *deleted = " (deleted)";
  if (file_path_length < strlen (deleted))
    {
      printf ("error: path in /proc is too short: %.*s\n",
              (int) file_path_length, file_path);
      exit (1);
    }
  return memcmp (file_path + file_path_length - strlen (deleted),
              deleted, strlen (deleted)) == 0;
}

/* Obtain a file name which is difficult to guess.  */
static char *
get_random_name (void)
{
  unsigned long long bytes[2];
  int random_device = open ("/dev/urandom", O_RDONLY);
  if (random_device < 0)
    {
      printf ("error: open (\"/dev/urandom\"): %m\n");
      exit (1);
    }
  ssize_t ret = read (random_device, bytes, sizeof (bytes));
  if (ret < 0)
    {
      printf ("error: read (\"/dev/urandom\"): %m\n");
      exit (1);
    }
  if (ret != sizeof (bytes))
    {
      printf ("error: short read from /dev/urandom: %zd\n", ret);
      exit (1);
    }
  close (random_device);
  return xasprintf ("tst-open-tmpfile-%08llx%08llx.tmp", bytes[0], bytes[1]);
}

/* Check open/openat (as specified by OP and WRAPPER) with a specific
   PATH/FLAGS/MODE combination.  */
static void
check_wrapper_flags_mode (const char *op, wrapper_func wrapper,
                          const char *path, int flags, mode_t mode)
{
  int fd = wrapper (path, flags | O_TMPFILE, mode);
  struct stat64 st;
  if (fstat64 (fd, &st) != 0)
    {
      printf ("error: fstat64: %m\n");
      exit (1);
    }

  /* Verify that the mode was correctly processed.  */
  int actual_mode = st.st_mode & 0777;
  if (actual_mode != mode)
    {
      printf ("error: unexpected mode; expected 0%03o, actual 0%03o\n",
              mode, actual_mode);
      exit (1);
    }

  /* Check that the file is marked as deleted in /proc.  */
  if (!is_file_deteted (fd))
    {
      printf ("error: path in /proc is not marked as deleted\n");
      exit (1);
    }

  /* Check that the file can be turned into a regular file with
     linkat.  Open a file descriptor for the directory at PATH.  Use
     AT_FDCWD if PATH is ".", to exercise that functionality as
     well.  */
  int path_fd;
  if (strcmp (path, ".") == 0)
    path_fd = AT_FDCWD;
  else
    {
      path_fd = open (path, O_RDONLY | O_DIRECTORY);
      if (path_fd < 0)
        {
          printf ("error: open (\"%s\"): %m\n", path);
          exit (1);
        }
    }

  /* Use a hard-to-guess name for the new directory entry.  */
  char *new_name = get_random_name ();

  /* linkat does not require privileges if the path in /proc/self/fd
     is used.  */
  char *proc_fd_path = xasprintf ("/proc/self/fd/%d", fd);
  if (linkat (AT_FDCWD, proc_fd_path, path_fd, new_name,
              AT_SYMLINK_FOLLOW) == 0)
    {
      if (unlinkat (path_fd, new_name, 0) != 0 && errno != ENOENT)
        {
          printf ("error: unlinkat (\"%s/%s\"): %m\n", path, new_name);
          exit (1);
        }
    }
  else
    {
      /* linkat failed.  This is expected if O_EXCL was specified.  */
      if ((flags & O_EXCL) == 0)
        {
          printf ("error: linkat failed after %s (\"%s\", 0x%x, 0%03o): %m\n",
                  op, path, flags, mode);
          exit (1);
        }
    }

  free (proc_fd_path);
  free (new_name);
  if (path_fd != AT_FDCWD)
    close (path_fd);
  close (fd);
}

/* Check OP/WRAPPER with various flags at a specific PATH and
   MODE.  */
static void
check_wrapper_mode (const char *op, wrapper_func wrapper,
                    const char *path, mode_t mode)
{
  check_wrapper_flags_mode (op, wrapper, path, O_WRONLY, mode);
  check_wrapper_flags_mode (op, wrapper, path, O_WRONLY | O_EXCL, mode);
  check_wrapper_flags_mode (op, wrapper, path, O_RDWR, mode);
  check_wrapper_flags_mode (op, wrapper, path, O_RDWR | O_EXCL, mode);
}

/* Check open/openat with varying permissions.  */
static void
check_wrapper (const char *op, wrapper_func wrapper,
                    const char *path)
{
  printf ("info: testing %s at: %s\n", op, path);
  check_wrapper_mode (op, wrapper, path, 0);
  check_wrapper_mode (op, wrapper, path, 0640);
  check_wrapper_mode (op, wrapper, path, 0600);
  check_wrapper_mode (op, wrapper, path, 0755);
  check_wrapper_mode (op, wrapper, path, 0750);
}

/* Verify that the directory at PATH supports O_TMPFILE.  Exit with
   status 77 (unsupported) if the kernel does not support O_TMPFILE.
   Even with kernel support, not all file systems O_TMPFILE, so return
   true if the directory supports O_TMPFILE, false if not.  */
static bool
probe_path (const char *path)
{
  int fd = openat (AT_FDCWD, path, O_TMPFILE | O_RDWR, 0);
  if (fd < 0)
    {
      if (errno == EISDIR)
        /* The system does not support O_TMPFILE.  */
        {
          printf ("info: kernel does not support O_TMPFILE\n");
          exit (77);
        }
      if (errno == EOPNOTSUPP)
        {
          printf ("info: path does not support O_TMPFILE: %s\n", path);
          return false;
        }
      printf ("error: openat (\"%s\", O_TMPFILE | O_RDWR): %m\n", path);
      exit (1);
    }
  close (fd);
  return true;
}

static int
do_test (void)
{
  umask (0);
  const char *paths[] = { ".", "/dev/shm", "/tmp",
                          getenv ("TEST_TMPFILE_PATH"),
                          NULL };
  bool supported = false;
  for (int i = 0; paths[i] != NULL; ++i)
    if (probe_path (paths[i]))
      {
        supported = true;
        check_wrapper ("open", wrap_open, paths[i]);
        check_wrapper ("openat", wrap_openat, paths[i]);
        check_wrapper ("open64", wrap_open64, paths[i]);
        check_wrapper ("openat64", wrap_openat64, paths[i]);
      }

  if (!supported)
    return 77;

  return 0;
}

#else  /* !O_TMPFILE */

static int
do_test (void)
{
  return 77;
}

#endif  /* O_TMPFILE */

#include <support/test-driver.c>