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.

1 files changed, 45 insertions, 371 deletions

diff --git a/cpukit/libfs/src/dosfs/msdos_eval.c b/cpukit/libfs/src/dosfs/msdos_eval.c
index 9b5e0c835d..0ab5971e62 100644
--- a/cpukit/libfs/src/dosfs/msdos_eval.c
+++ b/cpukit/libfs/src/dosfs/msdos_eval.c
@@ -52,384 +52,58 @@ msdos_set_handlers(rtems_filesystem_location_info_t *loc)
         loc->handlers = fs_info->file_handlers;
 }
 
-/* msdos_eval_path --
- *
- *     The following routine evaluate path for a node that wishes to be
- *     accessed.  Structure 'pathloc' is returned with a pointer to the
- *     node to be accessed.
- *
- * PARAMETERS:
- *     pathname - path for evaluation
- *     flags    - flags
- *     pathloc  - node description (IN/OUT)
- *
- * RETURNS:
- *     RC_OK and filled pathloc on success, or -1 if error occured
- *     (errno set appropriately)
- *
- */
-int
-msdos_eval_path(
-    const char                        *pathname,
-    size_t                             pathnamelen,
-    int                                flags,
-    rtems_filesystem_location_info_t  *pathloc
-    )
+static bool msdos_is_directory(
+  rtems_filesystem_eval_path_context_t *ctx,
+  void *arg
+)
 {
-    int                               rc = RC_OK;
-    rtems_status_code                 sc = RTEMS_SUCCESSFUL;
-    msdos_fs_info_t                  *fs_info = pathloc->mt_entry->fs_info;
-    fat_file_fd_t                    *fat_fd = NULL;
-    rtems_filesystem_location_info_t  newloc;
-    int                               i = 0;
-    int                               token_len = 0;
-    msdos_token_types_t               type = MSDOS_CURRENT_DIR;
-    const char                       *token;
-
-    sc = rtems_semaphore_obtain(fs_info->vol_sema, RTEMS_WAIT,
-                                MSDOS_VOLUME_SEMAPHORE_TIMEOUT);
-    if (sc != RTEMS_SUCCESSFUL)
-        rtems_set_errno_and_return_minus_one(EIO);
-
-    if (!pathloc->node_access)
-    {
-        errno = ENOENT;
-        rc = -1;
-        goto err;
-    }
-
-    fat_fd = pathloc->node_access;
-
-    rc = fat_file_reopen(fat_fd);
-    if (rc != RC_OK)
-        goto err;
-
-    while ((type != MSDOS_NO_MORE_PATH) && (type != MSDOS_INVALID_TOKEN))
-    {
-        type = msdos_get_token(&pathname[i], pathnamelen, &token, &token_len);
-        pathnamelen -= token_len;
-        i += token_len;
-
-        fat_fd = pathloc->node_access;
-
-        switch (type)
-        {
-            case MSDOS_UP_DIR:
-                /*
-                 *  Only a directory can be decended into.
-                 */
-                if (fat_fd->fat_file_type != FAT_DIRECTORY)
-                {
-                    errno = ENOTSUP;
-                    rc = -1;
-                    goto error;
-                }
+  rtems_filesystem_location_info_t *currentloc =
+    rtems_filesystem_eval_path_get_currentloc( ctx );
+  fat_file_fd_t *fat_fd = currentloc->node_access;
 
-                /*
-                 *  Am I at the root of this mounted filesystem?
-                 */
-                if (rtems_filesystem_is_root_location(pathloc))
-                {
-                    /*
-                     *  Am I at the root of all filesystems?
-                     *  XXX: MSDOS is not supposed to be base fs.
-                     */
-                    if (pathloc->node_access ==
-                        rtems_filesystem_root.node_access)
-                    {
-                        break;       /* Throw out the .. in this case */
-                    }
-                    else
-                    {
-                        newloc = pathloc->mt_entry->mt_point_node;
-                        *pathloc = newloc;
-
-                        rc = fat_file_close(pathloc->mt_entry, fat_fd);
-                        if (rc != RC_OK)
-                            goto err;
-
-                        rtems_semaphore_release(fs_info->vol_sema);
-                        return (*pathloc->ops->evalpath_h)(&(pathname[i-token_len]),
-                                                           pathnamelen + token_len,
-                                                           flags, pathloc);
-                    }
-                }
-                else
-                {
-                  rc = msdos_find_name(pathloc, token, token_len);
-                    if (rc != RC_OK)
-                    {
-                        if (rc == MSDOS_NAME_NOT_FOUND_ERR)
-                        {
-                            errno = ENOENT;
-                            rc = -1;
-                        }
-                        goto error;
-                    }
-                }
-                break;
-
-            case MSDOS_NAME:
-                /*
-                 *  Only a directory can be decended into.
-                 */
-                if (fat_fd->fat_file_type != FAT_DIRECTORY)
-                {
-                    errno = ENOTSUP;
-                    rc = -1;
-                    goto error;
-                }
-
-                /*
-                 *  Otherwise find the token name in the present location and
-                 * set the node access to the point we have found.
-                 */
-                rc = msdos_find_name(pathloc, token, token_len);
-                if (rc != RC_OK)
-                {
-                    if (rc == MSDOS_NAME_NOT_FOUND_ERR)
-                    {
-                        errno = ENOENT;
-                        rc = -1;
-                    }
-                    goto error;
-                }
-                break;
-
-            case MSDOS_NO_MORE_PATH:
-            case MSDOS_CURRENT_DIR:
-                break;
-
-            case MSDOS_INVALID_TOKEN:
-                errno = ENAMETOOLONG;
-                rc = -1;
-                goto error;
-                break;
-
-        }
-    }
-
-    /*
-     *  Always return the root node.
-     *
-     *  If we are at a node that is a mount point. Set loc to the
-     *  new fs root node and let let the mounted filesystem set the handlers.
-     *
-     *  NOTE: The behavior of stat() on a mount point appears to be
-     *        questionable.
-     *  NOTE: MSDOS filesystem currently doesn't support mount functionality ->
-     *        action not implemented
-     */
-    fat_fd = pathloc->node_access;
-
-    msdos_set_handlers(pathloc);
-
-    rtems_semaphore_release(fs_info->vol_sema);
-    return RC_OK;
-
-error:
-    fat_file_close(pathloc->mt_entry, fat_fd);
-
-err:
-    rtems_semaphore_release(fs_info->vol_sema);
-    return rc;
+  return fat_fd->fat_file_type == MSDOS_DIRECTORY;
 }
 
-/* msdos_eval4make --
- *     The following routine evaluate path for a new node to be created.
- *     'pathloc' is returned with a pointer to the parent of the new node.
- *     'name' is returned with a pointer to the first character in the
- *     new node name.  The parent node is verified to be a directory.
- *
- * PARAMETERS:
- *     path    - path for evaluation
- *     pathloc - IN/OUT (start point for evaluation/parent directory for
- *               creation)
- *     name    - new node name
- *
- * RETURNS:
- *     RC_OK, filled pathloc for parent directory and name of new node on
- *     success, or -1 if error occured (errno set appropriately)
- */
-int
-msdos_eval4make(
-    const char                         *path,
-    rtems_filesystem_location_info_t   *pathloc,
-    const char                        **name
-    )
+static rtems_filesystem_eval_path_generic_status msdos_eval_token(
+  rtems_filesystem_eval_path_context_t *ctx,
+  void *arg,
+  const char *token,
+  size_t tokenlen
+)
 {
-    int                               rc = RC_OK;
-    rtems_status_code                 sc = RTEMS_SUCCESSFUL;
-    msdos_fs_info_t                  *fs_info = pathloc->mt_entry->fs_info;
-    fat_file_fd_t                    *fat_fd = NULL;
-    rtems_filesystem_location_info_t  newloc;
-    msdos_token_types_t               type;
-    int                               i = 0;
-    int                               token_len;
-    const char                       *token;
-    bool                              done = false;
-
-    sc = rtems_semaphore_obtain(fs_info->vol_sema, RTEMS_WAIT,
-                                MSDOS_VOLUME_SEMAPHORE_TIMEOUT);
-    if (sc != RTEMS_SUCCESSFUL)
-        rtems_set_errno_and_return_minus_one(EIO);
-
-    if (!pathloc->node_access)
-    {
-        errno = ENOENT;
-        rc = -1;
-        goto err;
+  rtems_filesystem_eval_path_generic_status status =
+    RTEMS_FILESYSTEM_EVAL_PATH_GENERIC_DONE;
+
+  if (rtems_filesystem_is_current_directory(token, tokenlen)) {
+    rtems_filesystem_eval_path_clear_token(ctx);
+    status = RTEMS_FILESYSTEM_EVAL_PATH_GENERIC_CONTINUE;
+  } else {
+    rtems_filesystem_location_info_t *currentloc =
+      rtems_filesystem_eval_path_get_currentloc(ctx);
+    int rc = msdos_find_name(currentloc, token, tokenlen);
+
+    if (rc == RC_OK) {
+      rtems_filesystem_eval_path_clear_token(ctx);
+      msdos_set_handlers(currentloc);
+      if (rtems_filesystem_eval_path_has_path(ctx)) {
+        status = RTEMS_FILESYSTEM_EVAL_PATH_GENERIC_CONTINUE;
+      }
+    } else if (rc == MSDOS_NAME_NOT_FOUND_ERR) {
+      status = RTEMS_FILESYSTEM_EVAL_PATH_GENERIC_NO_ENTRY;
+    } else {
+      rtems_filesystem_eval_path_error(ctx, 0);
     }
+  }
 
-    fat_fd = pathloc->node_access;
-
-    rc = fat_file_reopen(fat_fd);
-    if (rc != RC_OK)
-        goto err;
-
-    while (!done)
-    {
-        type = msdos_get_token(&path[i], strlen(&path[i]), &token, &token_len);
-        i += token_len;
-        fat_fd = pathloc->node_access;
-
-        switch (type)
-        {
-            case MSDOS_UP_DIR:
-                /*
-                 *  Only a directory can be decended into.
-                 */
-                if (fat_fd->fat_file_type != FAT_DIRECTORY)
-                {
-                    errno = ENOTDIR;
-                    rc = -1;
-                    goto error;
-                }
-
-                /*
-                 *  Am I at the root of this mounted filesystem?
-                 */
-                if (rtems_filesystem_is_root_location(pathloc))
-                {
-                    /*
-                     *  Am I at the root of all filesystems?
-                     *  XXX: MSDOS is not supposed to be base fs.
-                     */
-                    if (pathloc->node_access ==
-                        rtems_filesystem_root.node_access)
-                    {
-                        break;       /* Throw out the .. in this case */
-                    }
-                    else
-                    {
-                        newloc = pathloc->mt_entry->mt_point_node;
-                        *pathloc = newloc;
-
-                        rc = fat_file_close(pathloc->mt_entry, fat_fd);
-                        if (rc != RC_OK)
-                            goto err;
-
-                        rtems_semaphore_release(fs_info->vol_sema);
-                        return (*pathloc->ops->evalformake_h)(&path[i-token_len],
-                                                              pathloc, name);
-                    }
-                }
-                else
-                {
-                    rc = msdos_find_name(pathloc, token, token_len);
-                    if (rc != RC_OK)
-                    {
-                        if (rc == MSDOS_NAME_NOT_FOUND_ERR)
-                        {
-                            errno = ENOENT;
-                            rc = -1;
-                        }
-                        goto error;
-                    }
-                }
-                break;
-
-            case MSDOS_NAME:
-                /*
-                 *  Only a directory can be decended into.
-                 */
-                if (fat_fd->fat_file_type != FAT_DIRECTORY)
-                {
-                    errno = ENOTDIR;
-                    rc = -1;
-                    goto error;
-                }
-
-                /*
-                 * Otherwise find the token name in the present location and
-                 * set the node access to the point we have found.
-                 */
-                rc = msdos_find_name(pathloc, token, token_len);
-                if (rc)
-                {
-                    if (rc != MSDOS_NAME_NOT_FOUND_ERR)
-                    {
-                        errno = ENOENT;
-                        rc = -1;
-                        goto error;
-                    }
-                    else
-                        done = true;
-                }
-                break;
-
-            case MSDOS_NO_MORE_PATH:
-                errno = EEXIST;
-                rc = -1;
-                goto error;
-                break;
-
-            case MSDOS_CURRENT_DIR:
-                break;
-
-            case MSDOS_INVALID_TOKEN:
-                errno = ENAMETOOLONG;
-                rc = -1;
-                goto error;
-                break;
-
-        }
-    }
-
-    *name = &path[i - token_len];
-
-    /*
-     * We have evaluated the path as far as we can.
-     * Verify there is not any invalid stuff at the end of the name.
-     */
-    for( ; path[i] != '\0'; i++)
-    {
-        if (!msdos_is_separator(path[i]))
-        {
-            errno = ENOENT;
-            rc = -1;
-            goto error;
-        }
-    }
-
-    fat_fd = pathloc->node_access;
-
-    if (fat_fd->fat_file_type != FAT_DIRECTORY)
-    {
-        errno = ENOTDIR;
-        rc = -1;
-        goto error;
-    }
-
-    msdos_set_handlers(pathloc);
-
-    rtems_semaphore_release(fs_info->vol_sema);
-    return RC_OK;
+  return status;
+}
 
-error:
-    fat_file_close(pathloc->mt_entry, fat_fd);
+static const rtems_filesystem_eval_path_generic_config msdos_eval_config = {
+  .is_directory = msdos_is_directory,
+  .eval_token = msdos_eval_token
+};
 
-err:
-    rtems_semaphore_release(fs_info->vol_sema);
-    return rc;
+void msdos_eval_path(rtems_filesystem_eval_path_context_t *ctx)
+{
+  rtems_filesystem_eval_path_generic(ctx, NULL, &msdos_eval_config);
 }