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


/*
 * 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 <fibril.h>
#include <fibril_sync.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 mutex.
 */
fibril_local 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)
{
    if (!vfs_files_init())
        return ENOMEM;
   
    unsigned 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));
            fibril_mutex_initialize(&files[i]->lock);
            vfs_file_addref(files[i]);
            return (int) i;
        }
    }
   
    return EMFILE;
}
 
/** Release file descriptor.
 *
 * @param fd        File descriptor being released.
 *
 * @return      EOK on success or EBADF if fd is an invalid file
 *          descriptor.
 */
int vfs_fd_free(int fd)
{
    if (!vfs_files_init())
        return ENOMEM;
   
    if ((fd < 0) || (fd >= MAX_OPEN_FILES) || (files[fd] == NULL))
        return EBADF;
   
    vfs_file_delref(files[fd]);
    files[fd] = NULL;
   
    return EOK;
}
 
/** 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 (!vfs_files_init())
        return NULL;
   
    if ((fd >= 0) && (fd < MAX_OPEN_FILES))
        return files[fd];
   
    return NULL;
}
 
/**
 * @}
 */
 

Rev 4528	Rev 4555
1	/*	1	/*
2	* Copyright (c) 2007 Jakub Jermar	2	* Copyright (c) 2007 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	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	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.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	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	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	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	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	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	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.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/** @addtogroup fs	29	/** @addtogroup fs
30	* @{	30	* @{
31	*/	31	*/
32		32
33	/**	33	/**
34	* @file vfs_file.c	34	* @file vfs_file.c
35	* @brief Various operations on files have their home in this file.	35	* @brief Various operations on files have their home in this file.
36	*/	36	*/
37		37
38	#include <errno.h>	38	#include <errno.h>
39	#include <stdlib.h>	39	#include <stdlib.h>
40	#include <string.h>	40	#include <string.h>
41	#include <assert.h>	41	#include <assert.h>
42	#include <bool.h>	42	#include <bool.h>
43	#include <fibril.h>	43	#include <fibril.h>
44	#include <fibril_sync.h>	44	#include <fibril_sync.h>
45	#include "vfs.h"	45	#include "vfs.h"
46		46
47	/**	47	/**
48	* This is a per-connection table of open files.	48	* This is a per-connection table of open files.
49	* Our assumption is that each client opens only one connection and therefore	49	* Our assumption is that each client opens only one connection and therefore
50	* there is one table of open files per task. However, this may not be the case	50	* there is one table of open files per task. However, this may not be the case
51	* and the client can open more connections to VFS. In that case, there will be	51	* and the client can open more connections to VFS. In that case, there will be
52	* several tables and several file handle name spaces per task. Besides of this,	52	* several tables and several file handle name spaces per task. Besides of this,
53	* the functionality will stay unchanged. So unless the client knows what it is	53	* the functionality will stay unchanged. So unless the client knows what it is
54	* doing, it should open one connection to VFS only.	54	* doing, it should open one connection to VFS only.
55	*	55	*
56	* Allocation of the open files table is deferred until the client makes the	56	* Allocation of the open files table is deferred until the client makes the
57	* first VFS_OPEN operation.	57	* first VFS_OPEN operation.
58	*	58	*
59	* This resource being per-connection and, in the first place, per-fibril, we	59	* This resource being per-connection and, in the first place, per-fibril, we
60	* don't need to protect it by a futex.	60	* don't need to protect it by a mutex.
61	*/	61	*/
62	fibril_local vfs_file_t **files = NULL;	62	fibril_local vfs_file_t **files = NULL;
63		63
64	/** Initialize the table of open files. */	64	/** Initialize the table of open files. */
65	bool vfs_files_init(void)	65	bool vfs_files_init(void)
66	{	66	{
67	if (!files) {	67	if (!files) {
68	files = malloc(MAX_OPEN_FILES * sizeof(vfs_file_t *));	68	files = malloc(MAX_OPEN_FILES * sizeof(vfs_file_t *));
69	if (!files)	69	if (!files)
70	return false;	70	return false;
71	memset(files, 0, MAX_OPEN_FILES * sizeof(vfs_file_t *));	71	memset(files, 0, MAX_OPEN_FILES * sizeof(vfs_file_t *));
72	}	72	}
73	return true;	73	return true;
74	}	74	}
75		75
76	/** Allocate a file descriptor.	76	/** Allocate a file descriptor.
77	*	77	*
78	* @return First available file descriptor or a negative error	78	* @return First available file descriptor or a negative error
79	* code.	79	* code.
80	*/	80	*/
81	int vfs_fd_alloc(void)	81	int vfs_fd_alloc(void)
82	{	82	{
83	if (!vfs_files_init())	83	if (!vfs_files_init())
84	return ENOMEM;	84	return ENOMEM;
85		85
86	unsigned int i;	86	unsigned int i;
87	for (i = 0; i < MAX_OPEN_FILES; i++) {	87	for (i = 0; i < MAX_OPEN_FILES; i++) {
88	if (!files[i]) {	88	if (!files[i]) {
89	files[i] = (vfs_file_t *) malloc(sizeof(vfs_file_t));	89	files[i] = (vfs_file_t *) malloc(sizeof(vfs_file_t));
90	if (!files[i])	90	if (!files[i])
91	return ENOMEM;	91	return ENOMEM;
92		92
93	memset(files[i], 0, sizeof(vfs_file_t));	93	memset(files[i], 0, sizeof(vfs_file_t));
94	fibril_mutex_initialize(&files[i]->lock);	94	fibril_mutex_initialize(&files[i]->lock);
95	vfs_file_addref(files[i]);	95	vfs_file_addref(files[i]);
96	return (int) i;	96	return (int) i;
97	}	97	}
98	}	98	}
99		99
100	return EMFILE;	100	return EMFILE;
101	}	101	}
102		102
103	/** Release file descriptor.	103	/** Release file descriptor.
104	*	104	*
105	* @param fd File descriptor being released.	105	* @param fd File descriptor being released.
106	*	106	*
107	* @return EOK on success or EBADF if fd is an invalid file	107	* @return EOK on success or EBADF if fd is an invalid file
108	* descriptor.	108	* descriptor.
109	*/	109	*/
110	int vfs_fd_free(int fd)	110	int vfs_fd_free(int fd)
111	{	111	{
112	if (!vfs_files_init())	112	if (!vfs_files_init())
113	return ENOMEM;	113	return ENOMEM;
114		114
115	if ((fd < 0) \|\| (fd >= MAX_OPEN_FILES) \|\| (files[fd] == NULL))	115	if ((fd < 0) \|\| (fd >= MAX_OPEN_FILES) \|\| (files[fd] == NULL))
116	return EBADF;	116	return EBADF;
117		117
118	vfs_file_delref(files[fd]);	118	vfs_file_delref(files[fd]);
119	files[fd] = NULL;	119	files[fd] = NULL;
120		120
121	return EOK;	121	return EOK;
122	}	122	}
123		123
124	/** Increment reference count of VFS file structure.	124	/** Increment reference count of VFS file structure.
125	*	125	*
126	* @param file File structure that will have reference count	126	* @param file File structure that will have reference count
127	* incremented.	127	* incremented.
128	*/	128	*/
129	void vfs_file_addref(vfs_file_t *file)	129	void vfs_file_addref(vfs_file_t *file)
130	{	130	{
131	/*	131	/*
132	* File structures are per-connection, so no-one, except the current	132	* File structures are per-connection, so no-one, except the current
133	* fibril, should have a reference to them. This is the reason we don't	133	* fibril, should have a reference to them. This is the reason we don't
134	* do any synchronization here.	134	* do any synchronization here.
135	*/	135	*/
136	file->refcnt++;	136	file->refcnt++;
137	}	137	}
138		138
139	/** Decrement reference count of VFS file structure.	139	/** Decrement reference count of VFS file structure.
140	*	140	*
141	* @param file File structure that will have reference count	141	* @param file File structure that will have reference count
142	* decremented.	142	* decremented.
143	*/	143	*/
144	void vfs_file_delref(vfs_file_t *file)	144	void vfs_file_delref(vfs_file_t *file)
145	{	145	{
146	if (file->refcnt-- == 1) {	146	if (file->refcnt-- == 1) {
147	/*	147	/*
148	* Lost the last reference to a file, need to drop our reference	148	* Lost the last reference to a file, need to drop our reference
149	* to the underlying VFS node.	149	* to the underlying VFS node.
150	*/	150	*/
151	vfs_node_delref(file->node);	151	vfs_node_delref(file->node);
152	free(file);	152	free(file);
153	}	153	}
154	}	154	}
155		155
156	/** Find VFS file structure for a given file descriptor.	156	/** Find VFS file structure for a given file descriptor.
157	*	157	*
158	* @param fd File descriptor.	158	* @param fd File descriptor.
159	*	159	*
160	* @return VFS file structure corresponding to fd.	160	* @return VFS file structure corresponding to fd.
161	*/	161	*/
162	vfs_file_t *vfs_file_get(int fd)	162	vfs_file_t *vfs_file_get(int fd)
163	{	163	{
164	if (!vfs_files_init())	164	if (!vfs_files_init())
165	return NULL;	165	return NULL;
166		166
167	if ((fd >= 0) && (fd < MAX_OPEN_FILES))	167	if ((fd >= 0) && (fd < MAX_OPEN_FILES))
168	return files[fd];	168	return files[fd];
169		169
170	return NULL;	170	return NULL;
171	}	171	}
172		172
173	/**	173	/**
174	* @}	174	* @}
175	*/	175	*/
176		176

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(root)/trunk/uspace/srv/vfs/vfs_file.c @ 3847 – Rev 4528 → 4555