0,0 → 1,156 |
/* |
* 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)); |
futex_initialize(&files[i]->lock, 1); |
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(fd < MAX_OPEN_FILES); |
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 the 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) |
{ |
if (fd < MAX_OPEN_FILES) |
return files[fd]; |
return NULL; |
} |
|
/** |
* @} |
*/ |