| 0,0 → 1,152 |
|---|
| /* |
| * Copyright (c) 2007 Jakub Jermar |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * - The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** @addtogroup fs |
| * @{ |
| */ |
| |
| /** |
| * @file vfs_file.c |
| * @brief Various operations on files have their home in this file. |
| */ |
| |
| #include <errno.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <assert.h> |
| #include <bool.h> |
| #include "vfs.h" |
| |
| /** |
| * This is a per-connection table of open files. |
| * Our assumption is that each client opens only one connection and therefore |
| * there is one table of open files per task. However, this may not be the case |
| * and the client can open more connections to VFS. In that case, there will be |
| * several tables and several file handle name spaces per task. Besides of this, |
| * the functionality will stay unchanged. So unless the client knows what it is |
| * doing, it should open one connection to VFS only. |
| * |
| * Allocation of the open files table is deferred until the client makes the |
| * first VFS_OPEN operation. |
| * |
| * This resource being per-connection and, in the first place, per-fibril, we |
| * don't need to protect it by a futex. |
| */ |
| __thread vfs_file_t **files = NULL; |
| |
| /** Initialize the table of open files. */ |
| bool vfs_files_init(void) |
| { |
| if (!files) { |
| files = malloc(MAX_OPEN_FILES * sizeof(vfs_file_t *)); |
| if (!files) |
| return false; |
| memset(files, 0, MAX_OPEN_FILES * sizeof(vfs_file_t *)); |
| } |
| return true; |
| } |
| |
| /** Allocate a file descriptor. |
| * |
| * @return First available file descriptor or a negative error |
| * code. |
| */ |
| int vfs_fd_alloc(void) |
| { |
| int i; |
| |
| for (i = 0; i < MAX_OPEN_FILES; i++) { |
| if (!files[i]) { |
| files[i] = (vfs_file_t *) malloc(sizeof(vfs_file_t)); |
| if (!files[i]) |
| return ENOMEM; |
| memset(files[i], 0, sizeof(vfs_file_t)); |
| vfs_file_addref(files[i]); |
| return i; |
| } |
| } |
| return EMFILE; |
| } |
| |
| /** Release file descriptor. |
| * |
| * @param fd File descriptor being released. |
| */ |
| void vfs_fd_free(int fd) |
| { |
| assert(files[fd] != NULL); |
| vfs_file_delref(files[fd]); |
| files[fd] = NULL; |
| } |
| |
| /** Increment reference count of VFS file structure. |
| * |
| * @param file File structure that will have reference count |
| * incremented. |
| */ |
| void vfs_file_addref(vfs_file_t *file) |
| { |
| /* |
| * File structures are per-connection, so no-one, except the current |
| * fibril, should have a reference to them. This is the reason we don't |
| * do any synchronization here. |
| */ |
| file->refcnt++; |
| } |
| |
| /** Decrement reference count of VFS file structure. |
| * |
| * @param file File structure that will have reference count |
| * decremented. |
| */ |
| void vfs_file_delref(vfs_file_t *file) |
| { |
| if (file->refcnt-- == 1) { |
| /* |
| * Lost last reference to a file, need to drop our reference |
| * to the underlying VFS node. |
| */ |
| vfs_node_delref(file->node); |
| free(file); |
| } |
| } |
| |
| /** Find VFS file structure for a given file descriptor. |
| * |
| * @param fd File descriptor. |
| * |
| * @return VFS file structure corresponding to fd. |
| */ |
| vfs_file_t *vfs_file_get(int fd) |
| { |
| return files[fd]; |
| } |
| |
| /** |
| * @} |
| */ |