1 | /* $Id: fsw_core.c 98103 2023-01-17 14:15:46Z vboxsync $ */
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2 | /** @file
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3 | * fsw_core.c - Core file system wrapper abstraction layer code.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2010-2023 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * The contents of this file may alternatively be used under the terms
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26 | * of the Common Development and Distribution License Version 1.0
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27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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28 | * in the VirtualBox distribution, in which case the provisions of the
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29 | * CDDL are applicable instead of those of the GPL.
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30 | *
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31 | * You may elect to license modified versions of this file under the
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32 | * terms and conditions of either the GPL or the CDDL or both.
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33 | *
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34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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35 | * ---------------------------------------------------------------------------
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36 | * This code is based on:
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37 | *
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38 | * Copyright (c) 2006 Christoph Pfisterer
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39 | *
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40 | * Redistribution and use in source and binary forms, with or without
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41 | * modification, are permitted provided that the following conditions are
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42 | * met:
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43 | *
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44 | * * Redistributions of source code must retain the above copyright
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45 | * notice, this list of conditions and the following disclaimer.
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46 | *
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47 | * * Redistributions in binary form must reproduce the above copyright
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48 | * notice, this list of conditions and the following disclaimer in the
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49 | * documentation and/or other materials provided with the
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50 | * distribution.
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51 | *
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52 | * * Neither the name of Christoph Pfisterer nor the names of the
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53 | * contributors may be used to endorse or promote products derived
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54 | * from this software without specific prior written permission.
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55 | *
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56 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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57 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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58 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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59 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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60 | * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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61 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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62 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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63 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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64 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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65 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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66 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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67 | */
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68 |
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69 | #include "fsw_core.h"
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70 |
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71 |
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72 | // functions
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73 |
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74 | static void fsw_blockcache_free(struct fsw_volume *vol);
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75 |
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76 | #define MAX_CACHE_LEVEL (5)
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77 |
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78 |
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79 | /**
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80 | * Mount a volume with a given file system driver. This function is called by the
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81 | * host driver to make a volume accessible. The file system driver to use is specified
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82 | * by a pointer to its dispatch table. The file system driver will look at the
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83 | * data on the volume to determine if it can read the format. If the volume is found
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84 | * unsuitable, FSW_UNSUPPORTED is returned.
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85 | *
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86 | * If this function returns FSW_SUCCESS, *vol_out points at a valid volume data
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87 | * structure. The caller must release it later by calling fsw_unmount.
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88 | *
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89 | * If this function returns an error status, the caller only needs to clean up its
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90 | * own buffers that may have been allocated through the read_block interface.
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91 | */
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92 |
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93 | fsw_status_t fsw_mount(void *host_data,
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94 | struct fsw_host_table *host_table,
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95 | struct fsw_fstype_table *fstype_table,
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96 | struct fsw_volume **vol_out)
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97 | {
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98 | fsw_status_t status;
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99 | struct fsw_volume *vol;
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100 |
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101 | // allocate memory for the structure
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102 | status = fsw_alloc_zero(fstype_table->volume_struct_size, (void **)&vol);
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103 | if (status)
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104 | return status;
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105 |
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106 | // initialize fields
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107 | vol->phys_blocksize = 512;
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108 | vol->log_blocksize = 512;
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109 | vol->label.type = FSW_STRING_TYPE_EMPTY;
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110 | vol->host_data = host_data;
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111 | vol->host_table = host_table;
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112 | vol->fstype_table = fstype_table;
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113 | vol->host_string_type = host_table->native_string_type;
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114 |
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115 | // let the fs driver mount the file system
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116 | status = vol->fstype_table->volume_mount(vol);
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117 | if (status)
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118 | goto errorexit;
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119 |
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120 | /// @todo anything else?
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121 |
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122 | *vol_out = vol;
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123 | return FSW_SUCCESS;
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124 |
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125 | errorexit:
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126 | fsw_unmount(vol);
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127 | return status;
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128 | }
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129 |
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130 | /**
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131 | * Unmount a volume by releasing all memory associated with it. This function is
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132 | * called by the host driver when a volume is no longer needed. It is also called
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133 | * by the core after a failed mount to clean up any allocated memory.
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134 | *
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135 | * Note that all dnodes must have been released before calling this function.
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136 | */
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137 |
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138 | void fsw_unmount(struct fsw_volume *vol)
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139 | {
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140 | if (vol->root)
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141 | fsw_dnode_release(vol->root);
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142 | /// @todo check that no other dnodes are still around
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143 |
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144 | vol->fstype_table->volume_free(vol);
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145 |
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146 | fsw_blockcache_free(vol);
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147 | fsw_strfree(&vol->label);
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148 | fsw_free(vol);
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149 | }
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150 |
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151 | /**
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152 | * Get in-depth information on the volume. This function can be called by the host
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153 | * driver to get additional information on the volume.
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154 | */
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155 |
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156 | fsw_status_t fsw_volume_stat(struct fsw_volume *vol, struct fsw_volume_stat *sb)
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157 | {
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158 | return vol->fstype_table->volume_stat(vol, sb);
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159 | }
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160 |
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161 | /**
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162 | * Set the physical and logical block sizes of the volume. This functions is called by
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163 | * the file system driver to announce the block sizes it wants to use for accessing
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164 | * the disk (physical) and for addressing file contents (logical).
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165 | * Usually both sizes will be the same but there may be file systems that need to access
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166 | * metadata at a smaller block size than the allocation unit for files.
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167 | *
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168 | * Calling this function causes the block cache to be dropped. All pointers returned
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169 | * from fsw_block_get become invalid. This function should only be called while
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170 | * mounting the file system, not as a part of file access operations.
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171 | *
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172 | * Both sizes are measured in bytes, must be powers of 2, and must not be smaller
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173 | * than 512 bytes. The logical block size cannot be smaller than the physical block size.
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174 | */
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175 |
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176 | void fsw_set_blocksize(struct fsw_volume *vol, fsw_u32 phys_blocksize, fsw_u32 log_blocksize)
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177 | {
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178 | /// @todo Check the sizes. Both must be powers of 2. log_blocksize must not be smaller than
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179 | // phys_blocksize.
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180 |
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181 | // drop core block cache if present
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182 | fsw_blockcache_free(vol);
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183 |
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184 | // signal host driver to drop caches etc.
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185 | vol->host_table->change_blocksize(vol,
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186 | vol->phys_blocksize, vol->log_blocksize,
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187 | phys_blocksize, log_blocksize);
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188 |
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189 | vol->phys_blocksize = phys_blocksize;
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190 | vol->log_blocksize = log_blocksize;
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191 | }
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192 |
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193 | /**
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194 | * Get a block of data from the disk. This function is called by the file system driver
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195 | * or by core functions. It calls through to the host driver's device access routine.
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196 | * Given a physical block number, it reads the block into memory (or fetches it from the
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197 | * block cache) and returns the address of the memory buffer. The caller should provide
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198 | * an indication of how important the block is in the cache_level parameter. Blocks with
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199 | * a low level are purged first. Some suggestions for cache levels:
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200 | *
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201 | * - 0: File data
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202 | * - 1: Directory data, symlink data
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203 | * - 2: File system metadata
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204 | * - 3..5: File system metadata with a high rate of access
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205 | *
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206 | * If this function returns successfully, the returned data pointer is valid until the
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207 | * caller calls fsw_block_release.
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208 | */
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209 |
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210 | fsw_status_t fsw_block_get(struct VOLSTRUCTNAME *vol, fsw_u32 phys_bno, fsw_u32 cache_level, void **buffer_out)
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211 | {
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212 | fsw_status_t status;
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213 | fsw_u32 i, discard_level, new_bcache_size;
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214 | struct fsw_blockcache *new_bcache;
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215 |
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216 | /// @todo allow the host driver to do its own caching; just call through if
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217 | // the appropriate function pointers are set
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218 |
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219 | if (cache_level > MAX_CACHE_LEVEL)
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220 | cache_level = MAX_CACHE_LEVEL;
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221 |
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222 | // check block cache
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223 | for (i = 0; i < vol->bcache_size; i++) {
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224 | if (vol->bcache[i].phys_bno == phys_bno) {
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225 | // cache hit!
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226 | if (vol->bcache[i].cache_level < cache_level)
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227 | vol->bcache[i].cache_level = cache_level; // promote the entry
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228 | vol->bcache[i].refcount++;
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229 | *buffer_out = vol->bcache[i].data;
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230 | return FSW_SUCCESS;
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231 | }
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232 | }
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233 |
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234 | // find a free entry in the cache table
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235 | for (i = 0; i < vol->bcache_size; i++) {
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236 | if (vol->bcache[i].phys_bno == FSW_INVALID_BNO)
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237 | break;
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238 | }
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239 | if (i >= vol->bcache_size) {
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240 | for (discard_level = 0; discard_level <= MAX_CACHE_LEVEL; discard_level++) {
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241 | for (i = 0; i < vol->bcache_size; i++) {
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242 | if (vol->bcache[i].refcount == 0 && vol->bcache[i].cache_level <= discard_level)
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243 | break;
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244 | }
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245 | if (i < vol->bcache_size)
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246 | break;
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247 | }
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248 | }
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249 | if (i >= vol->bcache_size) {
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250 | // enlarge / create the cache
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251 | if (vol->bcache_size < 16)
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252 | new_bcache_size = 16;
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253 | else
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254 | new_bcache_size = vol->bcache_size << 1;
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255 | status = fsw_alloc(new_bcache_size * sizeof(struct fsw_blockcache), &new_bcache);
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256 | if (status)
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257 | return status;
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258 | if (vol->bcache_size > 0)
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259 | fsw_memcpy(new_bcache, vol->bcache, vol->bcache_size * sizeof(struct fsw_blockcache));
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260 | for (i = vol->bcache_size; i < new_bcache_size; i++) {
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261 | new_bcache[i].refcount = 0;
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262 | new_bcache[i].cache_level = 0;
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263 | new_bcache[i].phys_bno = FSW_INVALID_BNO;
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264 | new_bcache[i].data = NULL;
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265 | }
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266 | i = vol->bcache_size;
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267 |
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268 | // switch caches
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269 | if (vol->bcache != NULL)
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270 | fsw_free(vol->bcache);
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271 | vol->bcache = new_bcache;
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272 | vol->bcache_size = new_bcache_size;
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273 | }
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274 | vol->bcache[i].phys_bno = FSW_INVALID_BNO;
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275 |
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276 | // read the data
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277 | if (vol->bcache[i].data == NULL) {
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278 | status = fsw_alloc(vol->phys_blocksize, &vol->bcache[i].data);
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279 | if (status)
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280 | return status;
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281 | }
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282 | status = vol->host_table->read_block(vol, phys_bno, vol->bcache[i].data);
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283 | if (status)
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284 | return status;
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285 |
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286 | vol->bcache[i].phys_bno = phys_bno;
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287 | vol->bcache[i].cache_level = cache_level;
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288 | vol->bcache[i].refcount = 1;
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289 | *buffer_out = vol->bcache[i].data;
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290 | return FSW_SUCCESS;
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291 | }
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292 |
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293 | /**
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294 | * Releases a disk block. This function must be called to release disk blocks returned
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295 | * from fsw_block_get.
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296 | */
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297 |
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298 | void fsw_block_release(struct VOLSTRUCTNAME *vol, fsw_u32 phys_bno, void *buffer)
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299 | {
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300 | fsw_u32 i;
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301 |
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302 | /// @todo allow the host driver to do its own caching; just call through if
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303 | // the appropriate function pointers are set
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304 |
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305 | // update block cache
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306 | for (i = 0; i < vol->bcache_size; i++) {
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307 | if (vol->bcache[i].phys_bno == phys_bno && vol->bcache[i].refcount > 0)
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308 | vol->bcache[i].refcount--;
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309 | }
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310 | }
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311 |
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312 | /**
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313 | * Release the block cache. Called internally when changing block sizes and when
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314 | * unmounting the volume. It frees all data occupied by the generic block cache.
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315 | */
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316 |
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317 | static void fsw_blockcache_free(struct fsw_volume *vol)
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318 | {
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319 | fsw_u32 i;
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320 |
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321 | for (i = 0; i < vol->bcache_size; i++) {
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322 | if (vol->bcache[i].data != NULL)
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323 | fsw_free(vol->bcache[i].data);
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324 | }
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325 | if (vol->bcache != NULL) {
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326 | fsw_free(vol->bcache);
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327 | vol->bcache = NULL;
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328 | }
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329 | vol->bcache_size = 0;
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330 | }
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331 |
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332 | /**
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333 | * Add a new dnode to the list of known dnodes. This internal function is used when a
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334 | * dnode is created to add it to the dnode list that is used to search for existing
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335 | * dnodes by id.
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336 | */
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337 |
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338 | static void fsw_dnode_register(struct fsw_volume *vol, struct fsw_dnode *dno)
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339 | {
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340 | dno->next = vol->dnode_head;
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341 | if (vol->dnode_head != NULL)
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342 | vol->dnode_head->prev = dno;
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343 | dno->prev = NULL;
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344 | vol->dnode_head = dno;
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345 | }
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346 |
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347 | /**
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348 | * Create a dnode representing the root directory. This function is called by the file system
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349 | * driver while mounting the file system. The root directory is special because it has no parent
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350 | * dnode, its name is defined to be empty, and its type is also fixed. Otherwise, this functions
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351 | * behaves in the same way as fsw_dnode_create.
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352 | */
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353 |
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354 | fsw_status_t fsw_dnode_create_root(struct fsw_volume *vol, fsw_u32 dnode_id, struct fsw_dnode **dno_out)
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355 | {
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356 | fsw_status_t status;
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357 | struct fsw_dnode *dno;
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358 |
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359 | // allocate memory for the structure
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360 | status = fsw_alloc_zero(vol->fstype_table->dnode_struct_size, (void **)&dno);
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361 | if (status)
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362 | return status;
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363 |
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364 | // fill the structure
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365 | dno->vol = vol;
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366 | dno->parent = NULL;
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367 | dno->dnode_id = dnode_id;
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368 | dno->type = FSW_DNODE_TYPE_DIR;
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369 | dno->refcount = 1;
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370 | dno->name.type = FSW_STRING_TYPE_EMPTY;
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371 | /// @todo instead, call a function to create an empty string in the native string type
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372 |
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373 | fsw_dnode_register(vol, dno);
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374 |
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375 | *dno_out = dno;
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376 | return FSW_SUCCESS;
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377 | }
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378 |
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379 | /**
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380 | * Create a new dnode representing a file system object. This function is called by
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381 | * the file system driver in response to directory lookup or read requests. Note that
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382 | * if there already is a dnode with the given dnode_id on record, then no new object
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383 | * is created. Instead, the existing dnode is returned and its reference count
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384 | * increased. All other parameters are ignored in this case.
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385 | *
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386 | * The type passed into this function may be FSW_DNODE_TYPE_UNKNOWN. It is sufficient
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387 | * to fill the type field during the dnode_fill call.
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388 | *
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389 | * The name parameter must describe a string with the object's name. A copy will be
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390 | * stored in the dnode structure for future reference. The name will not be used to
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391 | * shortcut directory lookups, but may be used to reconstruct paths.
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392 | *
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393 | * If the function returns successfully, *dno_out contains a pointer to the dnode
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394 | * that must be released by the caller with fsw_dnode_release.
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395 | */
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396 |
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397 | fsw_status_t fsw_dnode_create(struct fsw_dnode *parent_dno, fsw_u32 dnode_id, int type,
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398 | struct fsw_string *name, struct fsw_dnode **dno_out)
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399 | {
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400 | fsw_status_t status;
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401 | struct fsw_volume *vol = parent_dno->vol;
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402 | struct fsw_dnode *dno;
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403 |
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404 | // check if we already have a dnode with the same id
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405 | for (dno = vol->dnode_head; dno; dno = dno->next) {
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406 | if (dno->dnode_id == dnode_id) {
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407 | fsw_dnode_retain(dno);
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408 | *dno_out = dno;
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409 | return FSW_SUCCESS;
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410 | }
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411 | }
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412 |
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413 | // allocate memory for the structure
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414 | status = fsw_alloc_zero(vol->fstype_table->dnode_struct_size, (void **)&dno);
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415 | if (status)
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416 | return status;
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417 |
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418 | // fill the structure
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419 | dno->vol = vol;
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420 | dno->parent = parent_dno;
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421 | fsw_dnode_retain(dno->parent);
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422 | dno->dnode_id = dnode_id;
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423 | dno->type = type;
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424 | dno->refcount = 1;
|
---|
425 | status = fsw_strdup_coerce(&dno->name, vol->host_table->native_string_type, name);
|
---|
426 | if (status) {
|
---|
427 | fsw_free(dno);
|
---|
428 | return status;
|
---|
429 | }
|
---|
430 |
|
---|
431 | fsw_dnode_register(vol, dno);
|
---|
432 |
|
---|
433 | *dno_out = dno;
|
---|
434 | return FSW_SUCCESS;
|
---|
435 | }
|
---|
436 |
|
---|
437 | /**
|
---|
438 | * Increases the reference count of a dnode. This must be balanced with
|
---|
439 | * fsw_dnode_release calls. Note that some dnode functions return a retained
|
---|
440 | * dnode pointer to their caller.
|
---|
441 | */
|
---|
442 |
|
---|
443 | void fsw_dnode_retain(struct fsw_dnode *dno)
|
---|
444 | {
|
---|
445 | dno->refcount++;
|
---|
446 | }
|
---|
447 |
|
---|
448 | /**
|
---|
449 | * Release a dnode pointer, deallocating it if this was the last reference.
|
---|
450 | * This function decrements the reference counter of the dnode. If the counter
|
---|
451 | * reaches zero, the dnode is freed. Since the parent dnode is released
|
---|
452 | * during that process, this function may cause it to be freed, too.
|
---|
453 | */
|
---|
454 |
|
---|
455 | void fsw_dnode_release(struct fsw_dnode *dno)
|
---|
456 | {
|
---|
457 | struct fsw_volume *vol = dno->vol;
|
---|
458 | struct fsw_dnode *parent_dno;
|
---|
459 |
|
---|
460 | dno->refcount--;
|
---|
461 |
|
---|
462 | if (dno->refcount == 0) {
|
---|
463 | parent_dno = dno->parent;
|
---|
464 |
|
---|
465 | // de-register from volume's list
|
---|
466 | if (dno->next)
|
---|
467 | dno->next->prev = dno->prev;
|
---|
468 | if (dno->prev)
|
---|
469 | dno->prev->next = dno->next;
|
---|
470 | if (vol->dnode_head == dno)
|
---|
471 | vol->dnode_head = dno->next;
|
---|
472 |
|
---|
473 | // run fstype-specific cleanup
|
---|
474 | vol->fstype_table->dnode_free(vol, dno);
|
---|
475 |
|
---|
476 | fsw_strfree(&dno->name);
|
---|
477 | fsw_free(dno);
|
---|
478 |
|
---|
479 | // release our pointer to the parent, possibly deallocating it, too
|
---|
480 | if (parent_dno)
|
---|
481 | fsw_dnode_release(parent_dno);
|
---|
482 | }
|
---|
483 | }
|
---|
484 |
|
---|
485 | /**
|
---|
486 | * Get full information about a dnode from disk. This function is called by the host
|
---|
487 | * driver as well as by the core functions. Some file systems defer reading full
|
---|
488 | * information on a dnode until it is actually needed (i.e. separation between
|
---|
489 | * directory and inode information). This function makes sure that all information
|
---|
490 | * is available in the dnode structure. The following fields may not have a correct
|
---|
491 | * value until fsw_dnode_fill has been called:
|
---|
492 | *
|
---|
493 | * type, size
|
---|
494 | */
|
---|
495 |
|
---|
496 | fsw_status_t fsw_dnode_fill(struct fsw_dnode *dno)
|
---|
497 | {
|
---|
498 | /// @todo check a flag right here, call fstype's dnode_fill only once per dnode
|
---|
499 |
|
---|
500 | return dno->vol->fstype_table->dnode_fill(dno->vol, dno);
|
---|
501 | }
|
---|
502 |
|
---|
503 | /**
|
---|
504 | * Get extended information about a dnode. This function can be called by the host
|
---|
505 | * driver to get a full compliment of information about a dnode in addition to the
|
---|
506 | * fields of the fsw_dnode structure itself.
|
---|
507 | *
|
---|
508 | * Some data requires host-specific conversion to be useful (i.e. timestamps) and
|
---|
509 | * will be passed to callback functions instead of being written into the structure.
|
---|
510 | * These callbacks must be filled in by the caller.
|
---|
511 | */
|
---|
512 |
|
---|
513 | fsw_status_t fsw_dnode_stat(struct fsw_dnode *dno, struct fsw_dnode_stat *sb)
|
---|
514 | {
|
---|
515 | fsw_status_t status;
|
---|
516 |
|
---|
517 | status = fsw_dnode_fill(dno);
|
---|
518 | if (status)
|
---|
519 | return status;
|
---|
520 |
|
---|
521 | sb->used_bytes = 0;
|
---|
522 | status = dno->vol->fstype_table->dnode_stat(dno->vol, dno, sb);
|
---|
523 | if (!status && !sb->used_bytes)
|
---|
524 | sb->used_bytes = FSW_U64_DIV(dno->size + dno->vol->log_blocksize - 1, dno->vol->log_blocksize);
|
---|
525 | return status;
|
---|
526 | }
|
---|
527 |
|
---|
528 | /**
|
---|
529 | * Lookup a directory entry by name. This function is called by the host driver.
|
---|
530 | * Given a directory dnode and a file name, it looks up the named entry in the
|
---|
531 | * directory.
|
---|
532 | *
|
---|
533 | * If the dnode is not a directory, the call will fail. The caller is responsible for
|
---|
534 | * resolving symbolic links before calling this function.
|
---|
535 | *
|
---|
536 | * If the function returns FSW_SUCCESS, *child_dno_out points to the requested directory
|
---|
537 | * entry. The caller must call fsw_dnode_release on it.
|
---|
538 | */
|
---|
539 |
|
---|
540 | fsw_status_t fsw_dnode_lookup(struct fsw_dnode *dno,
|
---|
541 | struct fsw_string *lookup_name, struct fsw_dnode **child_dno_out)
|
---|
542 | {
|
---|
543 | fsw_status_t status;
|
---|
544 |
|
---|
545 | status = fsw_dnode_fill(dno);
|
---|
546 | if (status)
|
---|
547 | return status;
|
---|
548 | if (dno->type != FSW_DNODE_TYPE_DIR)
|
---|
549 | return FSW_UNSUPPORTED;
|
---|
550 |
|
---|
551 | return dno->vol->fstype_table->dir_lookup(dno->vol, dno, lookup_name, child_dno_out);
|
---|
552 | }
|
---|
553 |
|
---|
554 | /**
|
---|
555 | * Find a file system object by path. This function is called by the host driver.
|
---|
556 | * Given a directory dnode and a relative or absolute path, it walks the directory
|
---|
557 | * tree until it finds the target dnode. If an intermediate node turns out to be
|
---|
558 | * a symlink, it is resolved automatically. If the target node is a symlink, it
|
---|
559 | * is not resolved.
|
---|
560 | *
|
---|
561 | * If the function returns FSW_SUCCESS, *child_dno_out points to the requested directory
|
---|
562 | * entry. The caller must call fsw_dnode_release on it.
|
---|
563 | */
|
---|
564 |
|
---|
565 | fsw_status_t fsw_dnode_lookup_path(struct fsw_dnode *dno,
|
---|
566 | struct fsw_string *lookup_path, char separator,
|
---|
567 | struct fsw_dnode **child_dno_out)
|
---|
568 | {
|
---|
569 | fsw_status_t status;
|
---|
570 | struct fsw_volume *vol = dno->vol;
|
---|
571 | struct fsw_dnode *child_dno = NULL;
|
---|
572 | struct fsw_string lookup_name;
|
---|
573 | struct fsw_string remaining_path;
|
---|
574 | int root_if_empty;
|
---|
575 |
|
---|
576 | remaining_path = *lookup_path;
|
---|
577 | fsw_dnode_retain(dno);
|
---|
578 |
|
---|
579 | // loop over the path
|
---|
580 | for (root_if_empty = 1; fsw_strlen(&remaining_path) > 0; root_if_empty = 0) {
|
---|
581 | // parse next path component
|
---|
582 | fsw_strsplit(&lookup_name, &remaining_path, separator);
|
---|
583 |
|
---|
584 | FSW_MSG_DEBUG((FSW_MSGSTR("fsw_dnode_lookup_path: split into %d '%s' and %d '%s'\n"),
|
---|
585 | lookup_name.len, lookup_name.data,
|
---|
586 | remaining_path.len, remaining_path.data));
|
---|
587 |
|
---|
588 | if (fsw_strlen(&lookup_name) == 0) { // empty path component
|
---|
589 | if (root_if_empty)
|
---|
590 | child_dno = vol->root;
|
---|
591 | else
|
---|
592 | child_dno = dno;
|
---|
593 | fsw_dnode_retain(child_dno);
|
---|
594 |
|
---|
595 | } else {
|
---|
596 | // do an actual directory lookup
|
---|
597 |
|
---|
598 | // ensure we have full information
|
---|
599 | status = fsw_dnode_fill(dno);
|
---|
600 | if (status)
|
---|
601 | goto errorexit;
|
---|
602 |
|
---|
603 | // resolve symlink if necessary
|
---|
604 | if (dno->type == FSW_DNODE_TYPE_SYMLINK) {
|
---|
605 | status = fsw_dnode_resolve(dno, &child_dno);
|
---|
606 | if (status)
|
---|
607 | goto errorexit;
|
---|
608 |
|
---|
609 | // symlink target becomes the new dno
|
---|
610 | fsw_dnode_release(dno);
|
---|
611 | dno = child_dno; // is already retained
|
---|
612 | child_dno = NULL;
|
---|
613 |
|
---|
614 | // ensure we have full information
|
---|
615 | status = fsw_dnode_fill(dno);
|
---|
616 | if (status)
|
---|
617 | goto errorexit;
|
---|
618 | }
|
---|
619 |
|
---|
620 | // make sure we operate on a directory
|
---|
621 | if (dno->type != FSW_DNODE_TYPE_DIR) {
|
---|
622 | return FSW_UNSUPPORTED;
|
---|
623 | goto errorexit;
|
---|
624 | }
|
---|
625 |
|
---|
626 | // check special paths
|
---|
627 | if (fsw_streq_cstr(&lookup_name, ".")) { // self directory
|
---|
628 | child_dno = dno;
|
---|
629 | fsw_dnode_retain(child_dno);
|
---|
630 |
|
---|
631 | } else if (fsw_streq_cstr(&lookup_name, "..")) { // parent directory
|
---|
632 | if (dno->parent == NULL) {
|
---|
633 | // We cannot go up from the root directory. Caution: Certain apps like the EFI shell
|
---|
634 | // rely on this behaviour!
|
---|
635 | status = FSW_NOT_FOUND;
|
---|
636 | goto errorexit;
|
---|
637 | }
|
---|
638 | child_dno = dno->parent;
|
---|
639 | fsw_dnode_retain(child_dno);
|
---|
640 |
|
---|
641 | } else {
|
---|
642 | // do an actual lookup
|
---|
643 | status = vol->fstype_table->dir_lookup(vol, dno, &lookup_name, &child_dno);
|
---|
644 | if (status)
|
---|
645 | goto errorexit;
|
---|
646 | }
|
---|
647 | }
|
---|
648 |
|
---|
649 | // child_dno becomes the new dno
|
---|
650 | fsw_dnode_release(dno);
|
---|
651 | dno = child_dno; // is already retained
|
---|
652 | child_dno = NULL;
|
---|
653 |
|
---|
654 | FSW_MSG_DEBUG((FSW_MSGSTR("fsw_dnode_lookup_path: now at inode %d\n"), dno->dnode_id));
|
---|
655 | }
|
---|
656 |
|
---|
657 | *child_dno_out = dno;
|
---|
658 | return FSW_SUCCESS;
|
---|
659 |
|
---|
660 | errorexit:
|
---|
661 | FSW_MSG_DEBUG((FSW_MSGSTR("fsw_dnode_lookup_path: leaving with error %d\n"), status));
|
---|
662 | fsw_dnode_release(dno);
|
---|
663 | if (child_dno != NULL)
|
---|
664 | fsw_dnode_release(child_dno);
|
---|
665 | return status;
|
---|
666 | }
|
---|
667 |
|
---|
668 | /**
|
---|
669 | * Get the next directory item in sequential order. This function is called by the
|
---|
670 | * host driver to read the complete contents of a directory in sequential (file system
|
---|
671 | * defined) order. Calling this function returns the next entry. Iteration state is
|
---|
672 | * kept by a shandle on the directory's dnode. The caller must set up the shandle
|
---|
673 | * when starting the iteration.
|
---|
674 | *
|
---|
675 | * When the end of the directory is reached, this function returns FSW_NOT_FOUND.
|
---|
676 | * If the function returns FSW_SUCCESS, *child_dno_out points to the next directory
|
---|
677 | * entry. The caller must call fsw_dnode_release on it.
|
---|
678 | */
|
---|
679 |
|
---|
680 | fsw_status_t fsw_dnode_dir_read(struct fsw_shandle *shand, struct fsw_dnode **child_dno_out)
|
---|
681 | {
|
---|
682 | fsw_status_t status;
|
---|
683 | struct fsw_dnode *dno = shand->dnode;
|
---|
684 | fsw_u64 saved_pos;
|
---|
685 |
|
---|
686 | if (dno->type != FSW_DNODE_TYPE_DIR)
|
---|
687 | return FSW_UNSUPPORTED;
|
---|
688 |
|
---|
689 | saved_pos = shand->pos;
|
---|
690 | status = dno->vol->fstype_table->dir_read(dno->vol, dno, shand, child_dno_out);
|
---|
691 | if (status)
|
---|
692 | shand->pos = saved_pos;
|
---|
693 | return status;
|
---|
694 | }
|
---|
695 |
|
---|
696 | /**
|
---|
697 | * Read the target path of a symbolic link. This function is called by the host driver
|
---|
698 | * to read the "content" of a symbolic link, that is the relative or absolute path
|
---|
699 | * it points to.
|
---|
700 | *
|
---|
701 | * If the function returns FSW_SUCCESS, the string handle provided by the caller is
|
---|
702 | * filled with a string in the host's preferred encoding. The caller is responsible
|
---|
703 | * for calling fsw_strfree on the string.
|
---|
704 | */
|
---|
705 |
|
---|
706 | fsw_status_t fsw_dnode_readlink(struct fsw_dnode *dno, struct fsw_string *target_name)
|
---|
707 | {
|
---|
708 | fsw_status_t status;
|
---|
709 |
|
---|
710 | status = fsw_dnode_fill(dno);
|
---|
711 | if (status)
|
---|
712 | return status;
|
---|
713 | if (dno->type != FSW_DNODE_TYPE_SYMLINK)
|
---|
714 | return FSW_UNSUPPORTED;
|
---|
715 |
|
---|
716 | return dno->vol->fstype_table->readlink(dno->vol, dno, target_name);
|
---|
717 | }
|
---|
718 |
|
---|
719 | /**
|
---|
720 | * Read the target path of a symbolic link by accessing file data. This function can
|
---|
721 | * be called by the file system driver if the file system stores the target path
|
---|
722 | * as normal file data. This function will open an shandle, read the whole content
|
---|
723 | * of the file into a buffer, and build a string from that. Currently the encoding
|
---|
724 | * for the string is fixed as FSW_STRING_TYPE_ISO88591.
|
---|
725 | *
|
---|
726 | * If the function returns FSW_SUCCESS, the string handle provided by the caller is
|
---|
727 | * filled with a string in the host's preferred encoding. The caller is responsible
|
---|
728 | * for calling fsw_strfree on the string.
|
---|
729 | */
|
---|
730 |
|
---|
731 | fsw_status_t fsw_dnode_readlink_data(struct fsw_dnode *dno, struct fsw_string *link_target)
|
---|
732 | {
|
---|
733 | fsw_status_t status;
|
---|
734 | struct fsw_shandle shand;
|
---|
735 | fsw_u32 buffer_size;
|
---|
736 | char buffer[FSW_PATH_MAX];
|
---|
737 |
|
---|
738 | struct fsw_string s;
|
---|
739 |
|
---|
740 | if (dno->size > FSW_PATH_MAX)
|
---|
741 | return FSW_VOLUME_CORRUPTED;
|
---|
742 |
|
---|
743 | s.type = FSW_STRING_TYPE_ISO88591;
|
---|
744 | s.size = s.len = (int)dno->size;
|
---|
745 | s.data = buffer;
|
---|
746 |
|
---|
747 | // open shandle and read the data
|
---|
748 | status = fsw_shandle_open(dno, &shand);
|
---|
749 | if (status)
|
---|
750 | return status;
|
---|
751 | buffer_size = (fsw_u32)s.size;
|
---|
752 | status = fsw_shandle_read(&shand, &buffer_size, buffer);
|
---|
753 | fsw_shandle_close(&shand);
|
---|
754 | if (status)
|
---|
755 | return status;
|
---|
756 | if ((int)buffer_size < s.size)
|
---|
757 | return FSW_VOLUME_CORRUPTED;
|
---|
758 |
|
---|
759 | status = fsw_strdup_coerce(link_target, dno->vol->host_string_type, &s);
|
---|
760 | return status;
|
---|
761 | }
|
---|
762 |
|
---|
763 | /**
|
---|
764 | * Resolve a symbolic link. This function can be called by the host driver to make
|
---|
765 | * sure the a dnode is fully resolved instead of pointing at a symlink. If the dnode
|
---|
766 | * passed in is not a symlink, it is returned unmodified.
|
---|
767 | *
|
---|
768 | * Note that absolute paths will be resolved relative to the root directory of the
|
---|
769 | * volume. If the host is an operating system with its own VFS layer, it should
|
---|
770 | * resolve symlinks on its own.
|
---|
771 | *
|
---|
772 | * If the function returns FSW_SUCCESS, *target_dno_out points at a dnode that is
|
---|
773 | * not a symlink. The caller is responsible for calling fsw_dnode_release on it.
|
---|
774 | */
|
---|
775 |
|
---|
776 | fsw_status_t fsw_dnode_resolve(struct fsw_dnode *dno, struct fsw_dnode **target_dno_out)
|
---|
777 | {
|
---|
778 | fsw_status_t status;
|
---|
779 | struct fsw_string target_name;
|
---|
780 | struct fsw_dnode *target_dno;
|
---|
781 |
|
---|
782 | fsw_dnode_retain(dno);
|
---|
783 |
|
---|
784 | while (1) {
|
---|
785 | // get full information
|
---|
786 | status = fsw_dnode_fill(dno);
|
---|
787 | if (status)
|
---|
788 | goto errorexit;
|
---|
789 | if (dno->type != FSW_DNODE_TYPE_SYMLINK) {
|
---|
790 | // found a non-symlink target, return it
|
---|
791 | *target_dno_out = dno;
|
---|
792 | return FSW_SUCCESS;
|
---|
793 | }
|
---|
794 | if (dno->parent == NULL) { // safety measure, cannot happen in theory
|
---|
795 | status = FSW_NOT_FOUND;
|
---|
796 | goto errorexit;
|
---|
797 | }
|
---|
798 |
|
---|
799 | // read the link's target
|
---|
800 | status = fsw_dnode_readlink(dno, &target_name);
|
---|
801 | if (status)
|
---|
802 | goto errorexit;
|
---|
803 |
|
---|
804 | // resolve it
|
---|
805 | status = fsw_dnode_lookup_path(dno->parent, &target_name, '/', &target_dno);
|
---|
806 | fsw_strfree(&target_name);
|
---|
807 | if (status)
|
---|
808 | goto errorexit;
|
---|
809 |
|
---|
810 | // target_dno becomes the new dno
|
---|
811 | fsw_dnode_release(dno);
|
---|
812 | dno = target_dno; // is already retained
|
---|
813 | }
|
---|
814 |
|
---|
815 | errorexit:
|
---|
816 | fsw_dnode_release(dno);
|
---|
817 | return status;
|
---|
818 | }
|
---|
819 |
|
---|
820 | /**
|
---|
821 | * Set up a shandle (storage handle) to access a file's data. This function is called
|
---|
822 | * by the host driver and by the core when they need to access a file's data. It is also
|
---|
823 | * used in accessing the raw data of directories and symlinks if the file system uses
|
---|
824 | * the same mechanisms for storing the data of those items.
|
---|
825 | *
|
---|
826 | * The storage for the fsw_shandle structure is provided by the caller. The dnode and pos
|
---|
827 | * fields may be accessed, pos may also be written to to set the file pointer. The file's
|
---|
828 | * data size is available as shand->dnode->size.
|
---|
829 | *
|
---|
830 | * If this function returns FSW_SUCCESS, the caller must call fsw_shandle_close to release
|
---|
831 | * the dnode reference held by the shandle.
|
---|
832 | */
|
---|
833 |
|
---|
834 | fsw_status_t fsw_shandle_open(struct fsw_dnode *dno, struct fsw_shandle *shand)
|
---|
835 | {
|
---|
836 | fsw_status_t status;
|
---|
837 | struct fsw_volume *vol = dno->vol;
|
---|
838 |
|
---|
839 | // read full dnode information into memory
|
---|
840 | status = vol->fstype_table->dnode_fill(vol, dno);
|
---|
841 | if (status)
|
---|
842 | return status;
|
---|
843 |
|
---|
844 | // setup shandle
|
---|
845 | fsw_dnode_retain(dno);
|
---|
846 |
|
---|
847 | shand->dnode = dno;
|
---|
848 | shand->pos = 0;
|
---|
849 | shand->extent.type = FSW_EXTENT_TYPE_INVALID;
|
---|
850 |
|
---|
851 | return FSW_SUCCESS;
|
---|
852 | }
|
---|
853 |
|
---|
854 | /**
|
---|
855 | * Close a shandle after accessing the dnode's data. This function is called by the host
|
---|
856 | * driver or core functions when they are finished with accessing a file's data. It
|
---|
857 | * releases the dnode reference and frees any buffers associated with the shandle itself.
|
---|
858 | * The dnode is only released if this was the last reference using it.
|
---|
859 | */
|
---|
860 |
|
---|
861 | void fsw_shandle_close(struct fsw_shandle *shand)
|
---|
862 | {
|
---|
863 | if (shand->extent.type == FSW_EXTENT_TYPE_BUFFER)
|
---|
864 | fsw_free(shand->extent.buffer);
|
---|
865 | fsw_dnode_release(shand->dnode);
|
---|
866 | }
|
---|
867 |
|
---|
868 | /**
|
---|
869 | * Read data from a shandle (storage handle for a dnode). This function is called by the
|
---|
870 | * host driver or internally when data is read from a file. TODO: more
|
---|
871 | */
|
---|
872 |
|
---|
873 | fsw_status_t fsw_shandle_read(struct fsw_shandle *shand, fsw_u32 *buffer_size_inout, void *buffer_in)
|
---|
874 | {
|
---|
875 | fsw_status_t status;
|
---|
876 | struct fsw_dnode *dno = shand->dnode;
|
---|
877 | struct fsw_volume *vol = dno->vol;
|
---|
878 | fsw_u8 *buffer, *block_buffer;
|
---|
879 | fsw_u32 buflen, copylen, pos;
|
---|
880 | fsw_u32 log_bno, pos_in_extent, phys_bno, pos_in_physblock;
|
---|
881 | fsw_u32 cache_level;
|
---|
882 |
|
---|
883 | if (shand->pos >= dno->size) { // already at EOF
|
---|
884 | *buffer_size_inout = 0;
|
---|
885 | return FSW_SUCCESS;
|
---|
886 | }
|
---|
887 |
|
---|
888 | // initialize vars
|
---|
889 | buffer = buffer_in;
|
---|
890 | buflen = *buffer_size_inout;
|
---|
891 | pos = (fsw_u32)shand->pos;
|
---|
892 | cache_level = (dno->type != FSW_DNODE_TYPE_FILE) ? 1 : 0;
|
---|
893 | // restrict read to file size
|
---|
894 | if (buflen > dno->size - pos)
|
---|
895 | buflen = (fsw_u32)(dno->size - pos);
|
---|
896 |
|
---|
897 | while (buflen > 0) {
|
---|
898 | // get extent for the current logical block
|
---|
899 | log_bno = pos / vol->log_blocksize;
|
---|
900 | if (shand->extent.type == FSW_EXTENT_TYPE_INVALID ||
|
---|
901 | log_bno < shand->extent.log_start ||
|
---|
902 | log_bno >= shand->extent.log_start + shand->extent.log_count) {
|
---|
903 |
|
---|
904 | if (shand->extent.type == FSW_EXTENT_TYPE_BUFFER)
|
---|
905 | fsw_free(shand->extent.buffer);
|
---|
906 |
|
---|
907 | // ask the file system for the proper extent
|
---|
908 | shand->extent.log_start = log_bno;
|
---|
909 | status = vol->fstype_table->get_extent(vol, dno, &shand->extent);
|
---|
910 | if (status) {
|
---|
911 | shand->extent.type = FSW_EXTENT_TYPE_INVALID;
|
---|
912 | return status;
|
---|
913 | }
|
---|
914 | }
|
---|
915 |
|
---|
916 | pos_in_extent = pos - shand->extent.log_start * vol->log_blocksize;
|
---|
917 |
|
---|
918 | // dispatch by extent type
|
---|
919 | if (shand->extent.type == FSW_EXTENT_TYPE_PHYSBLOCK) {
|
---|
920 | // convert to physical block number and offset
|
---|
921 | phys_bno = shand->extent.phys_start + pos_in_extent / vol->phys_blocksize;
|
---|
922 | pos_in_physblock = pos_in_extent & (vol->phys_blocksize - 1);
|
---|
923 | copylen = vol->phys_blocksize - pos_in_physblock;
|
---|
924 | if (copylen > buflen)
|
---|
925 | copylen = buflen;
|
---|
926 |
|
---|
927 | // get one physical block
|
---|
928 | status = fsw_block_get(vol, phys_bno, cache_level, (void **)&block_buffer);
|
---|
929 | if (status)
|
---|
930 | return status;
|
---|
931 |
|
---|
932 | // copy data from it
|
---|
933 | fsw_memcpy(buffer, block_buffer + pos_in_physblock, copylen);
|
---|
934 | fsw_block_release(vol, phys_bno, block_buffer);
|
---|
935 |
|
---|
936 | } else if (shand->extent.type == FSW_EXTENT_TYPE_BUFFER) {
|
---|
937 | copylen = shand->extent.log_count * vol->log_blocksize - pos_in_extent;
|
---|
938 | if (copylen > buflen)
|
---|
939 | copylen = buflen;
|
---|
940 | fsw_memcpy(buffer, (fsw_u8 *)shand->extent.buffer + pos_in_extent, copylen);
|
---|
941 |
|
---|
942 | } else { // _SPARSE or _INVALID
|
---|
943 | copylen = shand->extent.log_count * vol->log_blocksize - pos_in_extent;
|
---|
944 | if (copylen > buflen)
|
---|
945 | copylen = buflen;
|
---|
946 | fsw_memzero(buffer, copylen);
|
---|
947 |
|
---|
948 | }
|
---|
949 |
|
---|
950 | buffer += copylen;
|
---|
951 | buflen -= copylen;
|
---|
952 | pos += copylen;
|
---|
953 | }
|
---|
954 |
|
---|
955 | *buffer_size_inout = (fsw_u32)(pos - shand->pos);
|
---|
956 | shand->pos = pos;
|
---|
957 |
|
---|
958 | return FSW_SUCCESS;
|
---|
959 | }
|
---|
960 |
|
---|
961 | // EOF
|
---|