WebSVN – HelenOS – Blame – /trunk/uspace/srv/vfs/vfs_file.c

Rev	Author	Line No.	Line
2593	jermar	1	/*
		2	* Copyright (c) 2007 Jakub Jermar
		3	* All rights reserved.
		4	*
		5	* Redistribution and use in source and binary forms, with or without
		6	* modification, are permitted provided that the following conditions
		7	* are met:
		8	*
		9	* - Redistributions of source code must retain the above copyright
		10	* notice, this list of conditions and the following disclaimer.
		11	* - Redistributions in binary form must reproduce the above copyright
		12	* notice, this list of conditions and the following disclaimer in the
		13	* documentation and/or other materials provided with the distribution.
		14	* - The name of the author may not be used to endorse or promote products
		15	* derived from this software without specific prior written permission.
		16	*
		17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
		18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
		20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		27	*/
		28
		29	/** @addtogroup fs
		30	* @{
		31	*/
		32
		33	/**
		34	* @file vfs_file.c
		35	* @brief Various operations on files have their home in this file.
		36	*/
		37
		38	#include <errno.h>
		39	#include <stdlib.h>
		40	#include <string.h>
		41	#include <assert.h>
		42	#include <bool.h>
4518	jermar	43	#include <fibril_sync.h>
2593	jermar	44	#include "vfs.h"
		45
		46	/**
		47	* This is a per-connection table of open files.
		48	* Our assumption is that each client opens only one connection and therefore
		49	* there is one table of open files per task. However, this may not be the case
		50	* and the client can open more connections to VFS. In that case, there will be
		51	* several tables and several file handle name spaces per task. Besides of this,
		52	* the functionality will stay unchanged. So unless the client knows what it is
		53	* doing, it should open one connection to VFS only.
		54	*
		55	* Allocation of the open files table is deferred until the client makes the
		56	* first VFS_OPEN operation.
		57	*
		58	* This resource being per-connection and, in the first place, per-fibril, we
		59	* don't need to protect it by a futex.
		60	*/
		61	__thread vfs_file_t **files = NULL;
		62
		63	/** Initialize the table of open files. */
		64	bool vfs_files_init(void)
		65	{
		66	if (!files) {
		67	files = malloc(MAX_OPEN_FILES * sizeof(vfs_file_t *));
		68	if (!files)
		69	return false;
		70	memset(files, 0, MAX_OPEN_FILES * sizeof(vfs_file_t *));
		71	}
		72	return true;
		73	}
		74
		75	/** Allocate a file descriptor.
		76	*
		77	* @return First available file descriptor or a negative error
		78	* code.
		79	*/
		80	int vfs_fd_alloc(void)
		81	{
4432	decky	82	if (!vfs_files_init())
		83	return ENOMEM;
		84
		85	unsigned int i;
2593	jermar	86	for (i = 0; i < MAX_OPEN_FILES; i++) {
		87	if (!files[i]) {
		88	files[i] = (vfs_file_t *) malloc(sizeof(vfs_file_t));
		89	if (!files[i])
		90	return ENOMEM;
4432	decky	91
2593	jermar	92	memset(files[i], 0, sizeof(vfs_file_t));
4518	jermar	93	fibril_mutex_initialize(&files[i]->lock);
2593	jermar	94	vfs_file_addref(files[i]);
4432	decky	95	return (int) i;
2593	jermar	96	}
		97	}
4432	decky	98
2593	jermar	99	return EMFILE;
		100	}
		101
		102	/** Release file descriptor.
		103	*
		104	* @param fd File descriptor being released.
3215	jermar	105	*
		106	* @return EOK on success or EBADF if fd is an invalid file
		107	* descriptor.
2593	jermar	108	*/
3215	jermar	109	int vfs_fd_free(int fd)
2593	jermar	110	{
4432	decky	111	if (!vfs_files_init())
		112	return ENOMEM;
		113
4362	jermar	114	if ((fd < 0) \|\| (fd >= MAX_OPEN_FILES) \|\| (files[fd] == NULL))
3215	jermar	115	return EBADF;
4432	decky	116
2593	jermar	117	vfs_file_delref(files[fd]);
		118	files[fd] = NULL;
4432	decky	119
3215	jermar	120	return EOK;
2593	jermar	121	}
		122
		123	/** Increment reference count of VFS file structure.
		124	*
		125	* @param file File structure that will have reference count
		126	* incremented.
		127	*/
		128	void vfs_file_addref(vfs_file_t *file)
		129	{
		130	/*
		131	* File structures are per-connection, so no-one, except the current
		132	* fibril, should have a reference to them. This is the reason we don't
		133	* do any synchronization here.
		134	*/
		135	file->refcnt++;
		136	}
		137
		138	/** Decrement reference count of VFS file structure.
		139	*
		140	* @param file File structure that will have reference count
		141	* decremented.
		142	*/
		143	void vfs_file_delref(vfs_file_t *file)
		144	{
		145	if (file->refcnt-- == 1) {
		146	/*
2731	jermar	147	* Lost the last reference to a file, need to drop our reference
2593	jermar	148	* to the underlying VFS node.
		149	*/
		150	vfs_node_delref(file->node);
		151	free(file);
		152	}
		153	}
		154
		155	/** Find VFS file structure for a given file descriptor.
		156	*
		157	* @param fd File descriptor.
		158	*
		159	* @return VFS file structure corresponding to fd.
		160	*/
		161	vfs_file_t *vfs_file_get(int fd)
		162	{
4432	decky	163	if (!vfs_files_init())
		164	return NULL;
		165
4362	jermar	166	if ((fd >= 0) && (fd < MAX_OPEN_FILES))
2624	jermar	167	return files[fd];
4432	decky	168
2624	jermar	169	return NULL;
2593	jermar	170	}
		171
		172	/**
		173	* @}
4432	decky	174	*/

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(root)/trunk/uspace/srv/vfs/vfs_file.c – Rev 4518