D-Bus  1.16.2
dbus-file-unix.c
1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2 /* dbus-file-unix.c unix related file implementation (internal to D-Bus implementation)
3  *
4  * Copyright (C) 2002, 2003, 2006 Red Hat, Inc.
5  * Copyright (C) 2003 CodeFactory AB
6  *
7  * SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
8  *
9  * Licensed under the Academic Free License version 2.1
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24  *
25  */
26 
27 #include <config.h>
28 
29 #include "dbus-protocol.h"
30 #include "dbus-errors.h"
31 #include "dbus-file.h"
32 #include "dbus-internals.h"
33 #include "dbus-sysdeps.h"
34 #include "dbus-sysdeps-unix.h"
35 
36 #ifdef HAVE_LINUX_MAGIC_H
37 #include <linux/magic.h>
38 #endif
39 #include <sys/stat.h>
40 #ifdef HAVE_SYS_VFS_H
41 #include <sys/vfs.h>
42 #endif
43 #include <stdio.h>
44 #include <fcntl.h>
45 #include <unistd.h>
46 #include <errno.h>
47 
48 #ifndef O_BINARY
49 #define O_BINARY 0
50 #endif
51 
64  const DBusString *filename,
65  DBusError *error)
66 {
67  int fd;
68  struct stat sb;
69 #if defined(HAVE_FSTATFS) && defined(PROC_SUPER_MAGIC)
70  struct statfs sfs;
71 #endif
72  int orig_len;
73  int total;
74  int file_size;
75  const char *filename_c;
76  dbus_bool_t is_procfs = FALSE;
77 
78  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
79 
80  filename_c = _dbus_string_get_const_data (filename);
81 
82  /* O_BINARY useful on Cygwin */
83  fd = open (filename_c, O_RDONLY | O_BINARY);
84  if (fd < 0)
85  {
86  dbus_set_error (error, _dbus_error_from_errno (errno),
87  "Failed to open \"%s\": %s",
88  filename_c,
89  _dbus_strerror (errno));
90  return FALSE;
91  }
92 
93  _dbus_verbose ("file fd %d opened\n", fd);
94 
95  if (fstat (fd, &sb) < 0)
96  {
97  dbus_set_error (error, _dbus_error_from_errno (errno),
98  "Failed to stat \"%s\": %s",
99  filename_c,
100  _dbus_strerror (errno));
101 
102  _dbus_verbose ("fstat() failed: %s",
103  _dbus_strerror (errno));
104 
105  _dbus_close (fd, NULL);
106 
107  return FALSE;
108  }
109 
110  if (sb.st_size > _DBUS_ONE_MEGABYTE)
111  {
113  "File size %lu of \"%s\" is too large.",
114  (unsigned long) sb.st_size, filename_c);
115  _dbus_close (fd, NULL);
116  return FALSE;
117  }
118 
119  /* procfs has different semantics - most files are 0 size,
120  * we can do only one read, and at most we can read 4M.
121  */
122 #if defined(HAVE_FSTATFS) && defined(PROC_SUPER_MAGIC)
123  if (sb.st_size == 0)
124  {
125  if (fstatfs(fd, &sfs) < 0)
126  {
127  dbus_set_error (error, _dbus_error_from_errno (errno),
128  "Failed to stat \"%s\": %s",
129  filename_c,
130  _dbus_strerror (errno));
131 
132  _dbus_verbose ("fstatvfs() failed: %s",
133  _dbus_strerror (errno));
134 
135  _dbus_close (fd, NULL);
136 
137  return FALSE;
138  }
139  if (sfs.f_type == PROC_SUPER_MAGIC)
140  is_procfs = TRUE;
141  }
142 #endif
143 
144  if (is_procfs)
145  file_size = _DBUS_ONE_MEGABYTE;
146  else
147  file_size = sb.st_size;
148 
149  total = 0;
150  orig_len = _dbus_string_get_length (str);
151  if (file_size > 0 && S_ISREG (sb.st_mode))
152  {
153  int bytes_read;
154 
155  do
156  {
157  bytes_read = _dbus_read (fd, str,
158  file_size - total);
159  if (bytes_read <= 0)
160  {
161  dbus_set_error (error, _dbus_error_from_errno (errno),
162  "Error reading \"%s\": %s",
163  filename_c,
164  _dbus_strerror (errno));
165 
166  _dbus_verbose ("read() failed: %s",
167  _dbus_strerror (errno));
168 
169  _dbus_close (fd, NULL);
170  _dbus_string_set_length (str, orig_len);
171  return FALSE;
172  }
173  else
174  total += bytes_read;
175  }
176  while (total < file_size && !is_procfs);
177 
178  _dbus_close (fd, NULL);
179  return TRUE;
180  }
181  else if (file_size != 0)
182  {
183  _dbus_verbose ("Can only open regular files at the moment.\n");
185  "\"%s\" is not a regular file",
186  filename_c);
187  _dbus_close (fd, NULL);
188  return FALSE;
189  }
190  else
191  {
192  _dbus_close (fd, NULL);
193  return TRUE;
194  }
195 }
196 
209  const DBusString *filename,
210  dbus_bool_t world_readable,
211  DBusError *error)
212 {
213  int fd;
214  int bytes_to_write;
215  const char *filename_c;
216  DBusString tmp_filename;
217  const char *tmp_filename_c;
218  int total;
219  dbus_bool_t need_unlink;
220  dbus_bool_t retval;
221 
222  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
223 
224  fd = -1;
225  retval = FALSE;
226  need_unlink = FALSE;
227 
228  if (!_dbus_string_init (&tmp_filename))
229  {
231  return FALSE;
232  }
233 
234  if (!_dbus_string_copy (filename, 0, &tmp_filename, 0))
235  {
237  _dbus_string_free (&tmp_filename);
238  return FALSE;
239  }
240 
241  if (!_dbus_string_append (&tmp_filename, "."))
242  {
244  _dbus_string_free (&tmp_filename);
245  return FALSE;
246  }
247 
248 #define N_TMP_FILENAME_RANDOM_BYTES 8
249  if (!_dbus_generate_random_ascii (&tmp_filename, N_TMP_FILENAME_RANDOM_BYTES,
250  error))
251  {
252  _dbus_string_free (&tmp_filename);
253  return FALSE;
254  }
255 
256  filename_c = _dbus_string_get_const_data (filename);
257  tmp_filename_c = _dbus_string_get_const_data (&tmp_filename);
258 
259  fd = open (tmp_filename_c, O_WRONLY | O_BINARY | O_EXCL | O_CREAT,
260  world_readable ? 0644 : 0600);
261  if (fd < 0)
262  {
263  dbus_set_error (error, _dbus_error_from_errno (errno),
264  "Could not create %s: %s", tmp_filename_c,
265  _dbus_strerror (errno));
266  goto out;
267  }
268  if (world_readable)
269  {
270  /* Ensure the file is world readable even in the presence of
271  * possibly restrictive umasks;
272  * see http://lists.freedesktop.org/archives/dbus/2010-September/013367.html
273  */
274  if (fchmod (fd, 0644) < 0)
275  {
276  dbus_set_error (error, _dbus_error_from_errno (errno),
277  "Could not chmod %s: %s", tmp_filename_c,
278  _dbus_strerror (errno));
279  goto out;
280  }
281  }
282 
283  _dbus_verbose ("tmp file fd %d opened\n", fd);
284 
285  need_unlink = TRUE;
286 
287  total = 0;
288  bytes_to_write = _dbus_string_get_length (str);
289 
290  while (total < bytes_to_write)
291  {
292  int bytes_written;
293 
294  bytes_written = _dbus_write (fd, str, total,
295  bytes_to_write - total);
296 
297  if (bytes_written <= 0)
298  {
299  dbus_set_error (error, _dbus_error_from_errno (errno),
300  "Could not write to %s: %s", tmp_filename_c,
301  _dbus_strerror (errno));
302 
303  goto out;
304  }
305 
306  total += bytes_written;
307  }
308 
309  if (fsync(fd))
310  {
311  dbus_set_error (error, _dbus_error_from_errno (errno),
312  "Could not synchronize file %s: %s",
313  tmp_filename_c, _dbus_strerror (errno));
314 
315  goto out;
316  }
317 
318  if (!_dbus_close (fd, NULL))
319  {
320  dbus_set_error (error, _dbus_error_from_errno (errno),
321  "Could not close file %s: %s",
322  tmp_filename_c, _dbus_strerror (errno));
323 
324  goto out;
325  }
326 
327  fd = -1;
328 
329  if (rename (tmp_filename_c, filename_c) < 0)
330  {
331  dbus_set_error (error, _dbus_error_from_errno (errno),
332  "Could not rename %s to %s: %s",
333  tmp_filename_c, filename_c,
334  _dbus_strerror (errno));
335 
336  goto out;
337  }
338 
339  need_unlink = FALSE;
340 
341  retval = TRUE;
342 
343  out:
344  /* close first, then unlink, to prevent ".nfs34234235" garbage
345  * files
346  */
347 
348  if (fd >= 0)
349  _dbus_close (fd, NULL);
350 
351  if (need_unlink && unlink (tmp_filename_c) < 0)
352  _dbus_verbose ("Failed to unlink temp file %s: %s\n",
353  tmp_filename_c, _dbus_strerror (errno));
354 
355  _dbus_string_free (&tmp_filename);
356 
357  _DBUS_ASSERT_ERROR_XOR_BOOL (error, retval);
358  return retval;
359 }
360 
369  DBusError *error)
370 {
371  const char *filename_c;
372 
373  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
374 
375  filename_c = _dbus_string_get_const_data (filename);
376  if (chmod (filename_c, 0644) == -1)
377  {
378  dbus_set_error (error,
380  "Could not change permissions of file %s: %s\n",
381  filename_c,
382  _dbus_strerror (errno));
383  return FALSE;
384  }
385  return TRUE;
386 }
387 
396  DBusError *error)
397 {
398  int fd;
399  const char *filename_c;
400 
401  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
402 
403  filename_c = _dbus_string_get_const_data (filename);
404 
405  fd = open (filename_c, O_WRONLY | O_BINARY | O_EXCL | O_CREAT,
406  0600);
407  if (fd < 0)
408  {
409  dbus_set_error (error,
411  "Could not create file %s: %s\n",
412  filename_c,
413  _dbus_strerror (errno));
414  return FALSE;
415  }
416 
417  _dbus_verbose ("exclusive file fd %d opened\n", fd);
418 
419  if (!_dbus_close (fd, NULL))
420  {
421  dbus_set_error (error,
423  "Could not close file %s: %s\n",
424  filename_c,
425  _dbus_strerror (errno));
426  return FALSE;
427  }
428 
429  return TRUE;
430 }
431 
441 _dbus_delete_file (const DBusString *filename,
442  DBusError *error)
443 {
444  const char *filename_c;
445 
446  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
447 
448  filename_c = _dbus_string_get_const_data (filename);
449 
450  if (unlink (filename_c) < 0)
451  {
453  "Failed to delete file %s: %s\n",
454  filename_c, _dbus_strerror (errno));
455  return FALSE;
456  }
457  else
458  return TRUE;
459 }
dbus_bool_t _dbus_string_append(DBusString *str, const char *buffer)
Appends a nul-terminated C-style string to a DBusString.
Definition: dbus-string.c:980
#define NULL
A null pointer, defined appropriately for C or C++.
dbus_bool_t _dbus_create_file_exclusively(const DBusString *filename, DBusError *error)
Creates the given file, failing if the file already exists.
dbus_bool_t _dbus_string_save_to_file(const DBusString *str, const DBusString *filename, dbus_bool_t world_readable, DBusError *error)
Writes a string out to a file.
int _dbus_write(int fd, const DBusString *buffer, int start, int len)
Thin wrapper around the write() system call that writes a part of a DBusString and handles EINTR for ...
dbus_bool_t _dbus_file_get_contents(DBusString *str, const DBusString *filename, DBusError *error)
Appends the contents of the given file to the string, returning error code.
dbus_bool_t _dbus_string_init(DBusString *str)
Initializes a string.
Definition: dbus-string.c:182
dbus_bool_t _dbus_string_copy(const DBusString *source, int start, DBusString *dest, int insert_at)
Like _dbus_string_move(), but does not delete the section of the source string that's copied to the d...
Definition: dbus-string.c:1345
dbus_bool_t _dbus_delete_file(const DBusString *filename, DBusError *error)
Deletes the given file.
const char * _dbus_error_from_errno(int error_number)
Converts a UNIX errno, or Windows errno or WinSock error value into a DBusError name.
Definition: dbus-sysdeps.c:565
dbus_uint32_t dbus_bool_t
A boolean, valid values are TRUE and FALSE.
Definition: dbus-types.h:37
dbus_bool_t _dbus_generate_random_ascii(DBusString *str, int n_bytes, DBusError *error)
Generates the given number of random bytes, where the bytes are chosen from the alphanumeric ASCII su...
Definition: dbus-sysdeps.c:525
dbus_bool_t _dbus_make_file_world_readable(const DBusString *filename, DBusError *error)
Makes the file readable by every user in the system.
int _dbus_read(int fd, DBusString *buffer, int count)
Thin wrapper around the read() system call that appends the data it reads to the DBusString buffer...
Object representing an exception.
Definition: dbus-errors.h:50
void dbus_set_error(DBusError *error, const char *name, const char *format,...)
Assigns an error name and message to a DBusError.
Definition: dbus-errors.c:356
void _dbus_string_free(DBusString *str)
Frees a string created by _dbus_string_init(), and fills it with the same contents as #_DBUS_STRING_I...
Definition: dbus-string.c:278
#define TRUE
Expands to "1".
#define DBUS_ERROR_FAILED
A generic error; "something went wrong" - see the error message for more.
#define DBUS_ERROR_NO_MEMORY
There was not enough memory to complete an operation.
dbus_bool_t _dbus_close(int fd, DBusError *error)
Closes a file descriptor.
#define FALSE
Expands to "0".
dbus_bool_t _dbus_string_set_length(DBusString *str, int length)
Sets the length of a string.
Definition: dbus-string.c:847