source: rtems/cpukit/libcsupport/src/__usrenv.c @ 3b7c123

4.115
Last change on this file since 3b7c123 was 3b7c123, checked in by Sebastian Huber <sebastian.huber@…>, on 03/13/12 at 10:33:51

Filesystem: Reference counting for locations

o A new data structure rtems_filesystem_global_location_t was

introduced to be used for

o the mount point location in the mount table entry,
o the file system root location in the mount table entry,
o the root directory location in the user environment, and
o the current directory location in the user environment.

During the path evaluation global start locations are obtained to
ensure that the current file system instance will be not unmounted in
the meantime.

o The user environment uses now reference counting and is protected

from concurrent access.

o The path evaluation process was completely rewritten and simplified.

The IMFS, RFS, NFS, and DOSFS use now a generic path evaluation
method. Recursive calls in the path evaluation have been replaced
with iteration to avoid stack overflows. Only the evaluation of
symbolic links is recursive. No dynamic memory allocations and
intermediate buffers are used in the high level path evaluation. No
global locks are held during the file system instance specific path
evaluation process.

o Recursive symbolic link evaluation is now limited by

RTEMS_FILESYSTEM_SYMLOOP_MAX. Applications can retrieve this value
via sysconf().

o The device file system (devFS) uses now no global variables and

allocation from the workspace. Node names are allocated from the
heap.

o The upper layer lseek() performs now some parameter checks.
o The upper layer ftruncate() performs now some parameter checks.
o unmask() is now restricted to the RWX flags and protected from

concurrent access.

o The fchmod_h and rmnod_h file system node handlers are now a file

system operation.

o The unlink_h operation has been removed. All nodes are now destroyed

with the rmnod_h operation.

o New lock_h, unlock_h, clonenod_h, and are_nodes_equal_h file system

operations.

o The path evaluation and file system operations are now protected by

per file system instance lock and unlock operations.

o Fix and test file descriptor duplicate in fcntl().
o New test fstests/fsnofs01.

  • Property mode set to 100644
File size: 5.6 KB
Line 
1/*
2 *  COPYRIGHT (c) 1989-2008.
3 *  On-Line Applications Research Corporation (OAR).
4 *
5 *  Modifications to support reference counting in the file system are
6 *  Copyright (c) 2012 embedded brains GmbH.
7 *
8 *  The license and distribution terms for this file may be
9 *  found in the file LICENSE in this distribution or at
10 *  http://www.rtems.com/license/LICENSE.
11 *
12 *  $Id$
13 */
14
15#if HAVE_CONFIG_H
16  #include "config.h"
17#endif
18
19#include <sys/stat.h>
20
21#include <rtems/libio_.h>
22
23static int null_handler_open(
24  rtems_libio_t *iop,
25  const char *path,
26  int oflag,
27  mode_t mode
28)
29{
30  return -1;
31}
32
33static int null_handler_fstat(
34  const rtems_filesystem_location_info_t *pathloc,
35  struct stat *buf
36)
37{
38  return -1;
39}
40
41const rtems_filesystem_file_handlers_r rtems_filesystem_null_handlers = {
42  .open_h = null_handler_open,
43  .close_h = rtems_filesystem_default_close,
44  .read_h = rtems_filesystem_default_read,
45  .write_h = rtems_filesystem_default_write,
46  .ioctl_h = rtems_filesystem_default_ioctl,
47  .lseek_h = rtems_filesystem_default_lseek,
48  .fstat_h = null_handler_fstat,
49  .ftruncate_h = rtems_filesystem_default_ftruncate,
50  .fsync_h = rtems_filesystem_default_fsync,
51  .fdatasync_h = rtems_filesystem_default_fdatasync,
52  .fcntl_h = rtems_filesystem_default_fcntl
53};
54
55static void null_op_lock_or_unlock(
56  rtems_filesystem_mount_table_entry_t *mt_entry
57)
58{
59  /* Do nothing */
60}
61
62static int null_op_mknod(
63  const rtems_filesystem_location_info_t *parentloc,
64  const char *name,
65  size_t namelen,
66  mode_t mode,
67  dev_t dev
68)
69{
70  return -1;
71}
72
73static int null_op_rmnod(
74  const rtems_filesystem_location_info_t *parentloc,
75  const rtems_filesystem_location_info_t *loc
76)
77{
78  return -1;
79}
80
81static int null_op_link(
82  const rtems_filesystem_location_info_t *parentloc,
83  const rtems_filesystem_location_info_t *targetloc,
84  const char *name,
85  size_t namelen
86)
87{
88  return -1;
89}
90
91static int null_op_fchmod(
92  const rtems_filesystem_location_info_t *pathloc,
93  mode_t mode
94)
95{
96  return -1;
97}
98
99static int null_op_chown(
100  const rtems_filesystem_location_info_t *loc,
101  uid_t owner,
102  gid_t group
103)
104{
105  return -1;
106}
107
108static int null_op_clonenode(
109  rtems_filesystem_location_info_t *loc
110)
111{
112  return -1;
113}
114
115static int null_op_mount(
116  rtems_filesystem_mount_table_entry_t *mt_entry
117)
118{
119  return -1;
120}
121
122static int null_op_fsmount_me(
123  rtems_filesystem_mount_table_entry_t *mt_entry,
124  const void *data
125)
126{
127  return -1;
128}
129
130static int null_op_unmount(
131  rtems_filesystem_mount_table_entry_t *mt_entry
132)
133{
134  return -1;
135}
136
137static void null_op_fsunmount_me(
138  rtems_filesystem_mount_table_entry_t *mt_entry
139)
140{
141  /* Do nothing */
142}
143
144static int null_op_utime(
145  const rtems_filesystem_location_info_t *loc,
146  time_t actime,
147  time_t modtime
148)
149{
150  return -1;
151}
152
153static int null_op_symlink(
154  const rtems_filesystem_location_info_t *parentloc,
155  const char *name,
156  size_t namelen,
157  const char *target
158)
159{
160  return -1;
161}
162
163static ssize_t null_op_readlink(
164  const rtems_filesystem_location_info_t *loc,
165  char *buf,
166  size_t bufsize
167)
168{
169  return -1;
170}
171
172static int null_op_rename(
173  const rtems_filesystem_location_info_t *oldparentloc,
174  const rtems_filesystem_location_info_t *oldloc,
175  const rtems_filesystem_location_info_t *newparentloc,
176  const char *name,
177  size_t namelen
178)
179{
180  return -1;
181}
182
183static int null_op_statvfs(
184  const rtems_filesystem_location_info_t *loc,
185  struct statvfs *buf
186)
187{
188  return -1;
189}
190
191static const rtems_filesystem_operations_table null_ops = {
192  .lock_h = null_op_lock_or_unlock,
193  .unlock_h = null_op_lock_or_unlock,
194  .eval_path_h = rtems_filesystem_default_eval_path,
195  .link_h = null_op_link,
196  .are_nodes_equal_h = rtems_filesystem_default_are_nodes_equal,
197  .node_type_h = rtems_filesystem_default_node_type,
198  .mknod_h = null_op_mknod,
199  .rmnod_h = null_op_rmnod,
200  .fchmod_h = null_op_fchmod,
201  .chown_h = null_op_chown,
202  .clonenod_h = null_op_clonenode,
203  .freenod_h = rtems_filesystem_default_freenode,
204  .mount_h = null_op_mount,
205  .fsmount_me_h = null_op_fsmount_me,
206  .unmount_h = null_op_unmount,
207  .fsunmount_me_h = null_op_fsunmount_me,
208  .utime_h = null_op_utime,
209  .symlink_h = null_op_symlink,
210  .readlink_h = null_op_readlink,
211  .rename_h = null_op_rename,
212  .statvfs_h = null_op_statvfs
213};
214
215rtems_filesystem_mount_table_entry_t rtems_filesystem_null_mt_entry = {
216  .location_chain = {
217    .Head = {
218      .Node = {
219        .next = &rtems_filesystem_global_location_null.location.mt_entry_node,
220        .previous = NULL
221      },
222      .fill = &rtems_filesystem_global_location_null.location.mt_entry_node,
223    }
224  },
225  .mt_point_node = &rtems_filesystem_global_location_null,
226  .mt_fs_root = &rtems_filesystem_global_location_null,
227  .mounted = false,
228  .writeable = false
229};
230
231rtems_filesystem_global_location_t rtems_filesystem_global_location_null = {
232  .location = {
233    .mt_entry_node = {
234      .next = &rtems_filesystem_null_mt_entry.location_chain.Tail.Node,
235      .previous = &rtems_filesystem_null_mt_entry.location_chain.Head.Node
236    },
237    .handlers = &rtems_filesystem_null_handlers,
238    .ops = &null_ops,
239    .mt_entry = &rtems_filesystem_null_mt_entry
240  },
241
242  /*
243   * The initial reference count accounts for the following references
244   *  o the root directory of the user environment,
245   *  o the current directory of the user environment,
246   *  o the root node of the null file system instance, and
247   *  o the mount point node of the null file system instance.
248   */
249  .reference_count = 4
250};
251
252rtems_user_env_t rtems_global_user_env = {
253  .current_directory = &rtems_filesystem_global_location_null,
254  .root_directory = &rtems_filesystem_global_location_null,
255  .umask = S_IWGRP | S_IWOTH
256};
257
258rtems_user_env_t *rtems_current_user_env = &rtems_global_user_env;
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