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