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2698 | jermar | 1 | /* |
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 | |||
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_lookup.c |
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35 | * @brief |
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36 | */ |
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37 | |||
2753 | jermar | 38 | #include "vfs.h" |
2698 | jermar | 39 | #include <ipc/ipc.h> |
40 | #include <async.h> |
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41 | #include <errno.h> |
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42 | #include <string.h> |
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2763 | jermar | 43 | #include <stdarg.h> |
2698 | jermar | 44 | #include <bool.h> |
45 | #include <futex.h> |
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46 | #include <libadt/list.h> |
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2753 | jermar | 47 | #include <vfs/canonify.h> |
2698 | jermar | 48 | |
49 | #define min(a, b) ((a) < (b) ? (a) : (b)) |
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50 | |||
2766 | jermar | 51 | futex_t plb_futex = FUTEX_INITIALIZER; |
2698 | jermar | 52 | link_t plb_head; /**< PLB entry ring buffer. */ |
53 | uint8_t *plb = NULL; |
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54 | |||
55 | /** Perform a path lookup. |
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56 | * |
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2752 | jermar | 57 | * @param path Path to be resolved; it must be a NULL-terminated |
58 | * string. |
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2700 | jermar | 59 | * @param lflag Flags to be used during lookup. |
2698 | jermar | 60 | * @param result Empty structure where the lookup result will be stored. |
2707 | jermar | 61 | * Can be NULL. |
2698 | jermar | 62 | * @param altroot If non-empty, will be used instead of rootfs as the root |
63 | * of the whole VFS tree. |
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64 | * |
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65 | * @return EOK on success or an error code from errno.h. |
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66 | */ |
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2752 | jermar | 67 | int vfs_lookup_internal(char *path, int lflag, vfs_lookup_res_t *result, |
2763 | jermar | 68 | vfs_pair_t *altroot, ...) |
2698 | jermar | 69 | { |
70 | vfs_pair_t *root; |
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71 | |||
72 | if (altroot) |
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73 | root = altroot; |
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74 | else |
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75 | root = (vfs_pair_t *) &rootfs; |
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76 | |||
77 | if (!root->fs_handle) |
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78 | return ENOENT; |
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79 | |||
2752 | jermar | 80 | size_t len; |
81 | path = canonify(path, &len); |
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82 | if (!path) |
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83 | return EINVAL; |
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84 | |||
2770 | jermar | 85 | fs_index_t index = 0; |
2763 | jermar | 86 | if (lflag & L_LINK) { |
87 | va_list ap; |
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88 | |||
89 | va_start(ap, altroot); |
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2770 | jermar | 90 | index = va_arg(ap, fs_index_t); |
2763 | jermar | 91 | va_end(ap); |
92 | } |
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93 | |||
2698 | jermar | 94 | futex_down(&plb_futex); |
95 | |||
96 | plb_entry_t entry; |
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97 | link_initialize(&entry.plb_link); |
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98 | entry.len = len; |
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99 | |||
100 | off_t first; /* the first free index */ |
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101 | off_t last; /* the last free index */ |
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102 | |||
103 | if (list_empty(&plb_head)) { |
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104 | first = 0; |
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105 | last = PLB_SIZE - 1; |
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106 | } else { |
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107 | plb_entry_t *oldest = list_get_instance(plb_head.next, |
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108 | plb_entry_t, plb_link); |
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109 | plb_entry_t *newest = list_get_instance(plb_head.prev, |
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110 | plb_entry_t, plb_link); |
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111 | |||
112 | first = (newest->index + newest->len) % PLB_SIZE; |
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113 | last = (oldest->index - 1) % PLB_SIZE; |
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114 | } |
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115 | |||
116 | if (first <= last) { |
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117 | if ((last - first) + 1 < len) { |
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118 | /* |
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119 | * The buffer cannot absorb the path. |
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120 | */ |
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121 | futex_up(&plb_futex); |
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122 | return ELIMIT; |
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123 | } |
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124 | } else { |
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125 | if (PLB_SIZE - ((first - last) + 1) < len) { |
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126 | /* |
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127 | * The buffer cannot absorb the path. |
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128 | */ |
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129 | futex_up(&plb_futex); |
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130 | return ELIMIT; |
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131 | } |
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132 | } |
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133 | |||
134 | /* |
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135 | * We know the first free index in PLB and we also know that there is |
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136 | * enough space in the buffer to hold our path. |
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137 | */ |
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138 | |||
139 | entry.index = first; |
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140 | entry.len = len; |
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141 | |||
142 | /* |
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143 | * Claim PLB space by inserting the entry into the PLB entry ring |
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144 | * buffer. |
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145 | */ |
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146 | list_append(&entry.plb_link, &plb_head); |
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147 | |||
148 | futex_up(&plb_futex); |
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149 | |||
150 | /* |
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151 | * Copy the path into PLB. |
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152 | */ |
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153 | size_t cnt1 = min(len, (PLB_SIZE - first) + 1); |
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154 | size_t cnt2 = len - cnt1; |
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155 | |||
156 | memcpy(&plb[first], path, cnt1); |
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157 | memcpy(plb, &path[cnt1], cnt2); |
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158 | |||
159 | ipc_call_t answer; |
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160 | int phone = vfs_grab_phone(root->fs_handle); |
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2763 | jermar | 161 | aid_t req = async_send_5(phone, VFS_LOOKUP, (ipcarg_t) first, |
2698 | jermar | 162 | (ipcarg_t) (first + len - 1) % PLB_SIZE, |
2763 | jermar | 163 | (ipcarg_t) root->dev_handle, (ipcarg_t) lflag, (ipcarg_t) index, |
164 | &answer); |
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2698 | jermar | 165 | vfs_release_phone(phone); |
166 | |||
167 | ipcarg_t rc; |
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168 | async_wait_for(req, &rc); |
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169 | |||
170 | futex_down(&plb_futex); |
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171 | list_remove(&entry.plb_link); |
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172 | /* |
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173 | * Erasing the path from PLB will come handy for debugging purposes. |
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174 | */ |
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175 | memset(&plb[first], 0, cnt1); |
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176 | memset(plb, 0, cnt2); |
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177 | futex_up(&plb_futex); |
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178 | |||
2707 | jermar | 179 | if ((rc == EOK) && result) { |
2770 | jermar | 180 | result->triplet.fs_handle = (fs_handle_t) IPC_GET_ARG1(answer); |
181 | result->triplet.dev_handle = (dev_handle_t) IPC_GET_ARG2(answer); |
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182 | result->triplet.index = (fs_index_t) IPC_GET_ARG3(answer); |
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2698 | jermar | 183 | result->size = (size_t) IPC_GET_ARG4(answer); |
2730 | jermar | 184 | result->lnkcnt = (unsigned) IPC_GET_ARG5(answer); |
2698 | jermar | 185 | } |
186 | |||
187 | return rc; |
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188 | } |
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189 | |||
190 | /** |
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191 | * @} |
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2751 | jermar | 192 | */ |