1 | /*
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2 | * Copyright (c) 2008 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 |
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29 | /** @addtogroup fs
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30 | * @{
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31 | */
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32 |
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33 | /**
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34 | * @file vfs_lookup.c
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35 | * @brief
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36 | */
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37 |
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38 | #include "vfs.h"
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39 | #include <ipc/ipc.h>
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40 | #include <macros.h>
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41 | #include <async.h>
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42 | #include <errno.h>
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43 | #include <str.h>
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44 | #include <stdarg.h>
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45 | #include <bool.h>
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46 | #include <fibril_synch.h>
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47 | #include <adt/list.h>
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48 | #include <vfs/canonify.h>
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49 |
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50 | #define min(a, b) ((a) < (b) ? (a) : (b))
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51 |
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52 | FIBRIL_MUTEX_INITIALIZE(plb_mutex);
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53 | LIST_INITIALIZE(plb_head); /**< PLB entry ring buffer. */
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54 | uint8_t *plb = NULL;
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55 |
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56 | /** Perform a path lookup.
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57 | *
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58 | * @param path Path to be resolved; it must be a NULL-terminated
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59 | * string.
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60 | * @param lflag Flags to be used during lookup.
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61 | * @param result Empty structure where the lookup result will be stored.
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62 | * Can be NULL.
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63 | * @param altroot If non-empty, will be used instead of rootfs as the root
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64 | * of the whole VFS tree.
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65 | *
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66 | * @return EOK on success or an error code from errno.h.
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67 | *
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68 | */
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69 | int vfs_lookup_internal(char *path, int lflag, vfs_lookup_res_t *result,
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70 | vfs_pair_t *altroot, ...)
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71 | {
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72 | vfs_pair_t *root;
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73 |
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74 | if (altroot)
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75 | root = altroot;
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76 | else
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77 | root = &rootfs;
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78 |
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79 | if (!root->fs_handle)
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80 | return ENOENT;
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81 |
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82 | size_t len;
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83 | path = canonify(path, &len);
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84 | if (!path)
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85 | return EINVAL;
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86 |
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87 | fs_index_t index = 0;
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88 | if (lflag & L_LINK) {
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89 | va_list ap;
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90 |
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91 | va_start(ap, altroot);
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92 | index = va_arg(ap, fs_index_t);
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93 | va_end(ap);
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94 | }
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95 |
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96 | fibril_mutex_lock(&plb_mutex);
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97 |
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98 | plb_entry_t entry;
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99 | link_initialize(&entry.plb_link);
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100 | entry.len = len;
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101 |
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102 | size_t first; /* the first free index */
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103 | size_t last; /* the last free index */
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104 |
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105 | if (list_empty(&plb_head)) {
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106 | first = 0;
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107 | last = PLB_SIZE - 1;
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108 | } else {
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109 | plb_entry_t *oldest = list_get_instance(plb_head.next,
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110 | plb_entry_t, plb_link);
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111 | plb_entry_t *newest = list_get_instance(plb_head.prev,
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112 | plb_entry_t, plb_link);
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113 |
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114 | first = (newest->index + newest->len) % PLB_SIZE;
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115 | last = (oldest->index - 1) % PLB_SIZE;
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116 | }
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117 |
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118 | if (first <= last) {
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119 | if ((last - first) + 1 < len) {
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120 | /*
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121 | * The buffer cannot absorb the path.
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122 | */
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123 | fibril_mutex_unlock(&plb_mutex);
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124 | return ELIMIT;
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125 | }
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126 | } else {
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127 | if (PLB_SIZE - ((first - last) + 1) < len) {
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128 | /*
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129 | * The buffer cannot absorb the path.
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130 | */
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131 | fibril_mutex_unlock(&plb_mutex);
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132 | return ELIMIT;
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133 | }
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134 | }
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135 |
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136 | /*
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137 | * We know the first free index in PLB and we also know that there is
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138 | * enough space in the buffer to hold our path.
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139 | */
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140 |
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141 | entry.index = first;
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142 | entry.len = len;
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143 |
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144 | /*
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145 | * Claim PLB space by inserting the entry into the PLB entry ring
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146 | * buffer.
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147 | */
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148 | list_append(&entry.plb_link, &plb_head);
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149 |
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150 | fibril_mutex_unlock(&plb_mutex);
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151 |
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152 | /*
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153 | * Copy the path into PLB.
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154 | */
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155 | size_t cnt1 = min(len, (PLB_SIZE - first) + 1);
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156 | size_t cnt2 = len - cnt1;
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157 |
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158 | memcpy(&plb[first], path, cnt1);
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159 | memcpy(plb, &path[cnt1], cnt2);
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160 |
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161 | ipc_call_t answer;
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162 | int phone = vfs_grab_phone(root->fs_handle);
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163 | aid_t req = async_send_5(phone, VFS_OUT_LOOKUP, (ipcarg_t) first,
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164 | (ipcarg_t) (first + len - 1) % PLB_SIZE,
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165 | (ipcarg_t) root->devmap_handle, (ipcarg_t) lflag, (ipcarg_t) index,
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166 | &answer);
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167 |
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168 | ipcarg_t rc;
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169 | async_wait_for(req, &rc);
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170 | vfs_release_phone(root->fs_handle, phone);
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171 |
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172 | fibril_mutex_lock(&plb_mutex);
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173 | list_remove(&entry.plb_link);
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174 | /*
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175 | * Erasing the path from PLB will come handy for debugging purposes.
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176 | */
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177 | memset(&plb[first], 0, cnt1);
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178 | memset(plb, 0, cnt2);
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179 | fibril_mutex_unlock(&plb_mutex);
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180 |
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181 | if (((int) rc < EOK) || (!result))
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182 | return (int) rc;
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183 |
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184 | result->triplet.fs_handle = (fs_handle_t) rc;
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185 | result->triplet.devmap_handle = (devmap_handle_t) IPC_GET_ARG1(answer);
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186 | result->triplet.index = (fs_index_t) IPC_GET_ARG2(answer);
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187 | result->size =
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188 | (aoff64_t) MERGE_LOUP32(IPC_GET_ARG3(answer), IPC_GET_ARG4(answer));
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189 | result->lnkcnt = (unsigned int) IPC_GET_ARG5(answer);
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190 |
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191 | if (lflag & L_FILE)
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192 | result->type = VFS_NODE_FILE;
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193 | else if (lflag & L_DIRECTORY)
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194 | result->type = VFS_NODE_DIRECTORY;
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195 | else
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196 | result->type = VFS_NODE_UNKNOWN;
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197 |
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198 | return EOK;
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199 | }
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200 |
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201 | /** Perform a node open operation.
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202 | *
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203 | * @return EOK on success or an error code from errno.h.
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204 | *
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205 | */
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206 | int vfs_open_node_internal(vfs_lookup_res_t *result)
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207 | {
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208 | int phone = vfs_grab_phone(result->triplet.fs_handle);
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209 |
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210 | ipc_call_t answer;
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211 | aid_t req = async_send_2(phone, VFS_OUT_OPEN_NODE,
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212 | (ipcarg_t) result->triplet.devmap_handle,
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213 | (ipcarg_t) result->triplet.index, &answer);
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214 |
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215 | ipcarg_t rc;
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216 | async_wait_for(req, &rc);
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217 | vfs_release_phone(result->triplet.fs_handle, phone);
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218 |
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219 | if (rc == EOK) {
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220 | result->size =
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221 | MERGE_LOUP32(IPC_GET_ARG1(answer), IPC_GET_ARG2(answer));
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222 | result->lnkcnt = (unsigned int) IPC_GET_ARG3(answer);
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223 | if (IPC_GET_ARG4(answer) & L_FILE)
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224 | result->type = VFS_NODE_FILE;
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225 | else if (IPC_GET_ARG4(answer) & L_DIRECTORY)
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226 | result->type = VFS_NODE_DIRECTORY;
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227 | else
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228 | result->type = VFS_NODE_UNKNOWN;
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229 | }
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230 |
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231 | return rc;
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232 | }
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233 |
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234 | /**
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235 | * @}
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236 | */
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