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| Rev | Author | Line No. | Line |
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| 2542 | jermar | 1 | /* |
| 2 | * Copyright (c) 2007 Jakub Jermar |
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| 3 | * All rights reserved. |
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| 4 | * |
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| 5 | * Redistribution and use in source and binary forms, with or without |
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| 6 | * modification, are permitted provided that the following conditions |
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| 7 | * are met: |
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| 8 | * |
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| 9 | * - Redistributions of source code must retain the above copyright |
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| 10 | * notice, this list of conditions and the following disclaimer. |
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| 11 | * - Redistributions in binary form must reproduce the above copyright |
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| 12 | * notice, this list of conditions and the following disclaimer in the |
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| 13 | * documentation and/or other materials provided with the distribution. |
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| 14 | * - The name of the author may not be used to endorse or promote products |
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| 15 | * derived from this software without specific prior written permission. |
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| 16 | * |
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | */ |
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| 28 | |||
| 29 | /** @addtogroup fs |
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| 30 | * @{ |
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| 31 | */ |
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| 32 | |||
| 33 | /** |
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| 34 | * @file vfs.c |
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| 35 | * @brief VFS_LOOKUP method and Path Lookup Buffer code. |
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| 36 | */ |
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| 37 | |||
| 38 | #include <ipc/ipc.h> |
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| 39 | #include <async.h> |
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| 40 | #include <errno.h> |
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| 41 | #include <stdlib.h> |
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| 42 | #include <string.h> |
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| 43 | #include <bool.h> |
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| 44 | #include <futex.h> |
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| 45 | #include <libadt/list.h> |
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| 46 | #include "vfs.h" |
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| 47 | |||
| 2544 | jermar | 48 | #define min(a, b) ((a) < (b) ? (a) : (b)) |
| 49 | |||
| 2542 | jermar | 50 | atomic_t plb_futex = FUTEX_INITIALIZER; |
| 2544 | jermar | 51 | link_t plb_head; /**< PLB entry ring buffer. */ |
| 2542 | jermar | 52 | uint8_t *plb = NULL; |
| 53 | |||
| 2544 | jermar | 54 | int vfs_lookup_internal(char *path, size_t len, vfs_node_t *result) |
| 2542 | jermar | 55 | { |
| 2544 | jermar | 56 | if (!len) |
| 57 | return EINVAL; |
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| 58 | |||
| 2542 | jermar | 59 | if (!rootfs) |
| 2544 | jermar | 60 | return ENOENT; |
| 61 | |||
| 62 | futex_down(&plb_futex); |
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| 63 | |||
| 64 | plb_entry_t entry; |
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| 65 | link_initialize(&entry.plb_link); |
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| 66 | entry.len = len; |
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| 67 | |||
| 68 | off_t first; /* the first free index */ |
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| 69 | off_t last; /* the last free index */ |
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| 70 | |||
| 71 | if (list_empty(&plb_head)) { |
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| 72 | first = 0; |
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| 73 | last = PLB_SIZE - 1; |
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| 74 | } else { |
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| 75 | plb_entry_t *oldest = list_get_instance(plb_head.next, |
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| 76 | plb_entry_t, plb_link); |
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| 77 | plb_entry_t *newest = list_get_instance(plb_head.prev, |
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| 78 | plb_entry_t, plb_link); |
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| 79 | |||
| 80 | first = (newest->index + newest->len) % PLB_SIZE; |
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| 81 | last = (oldest->index - 1) % PLB_SIZE; |
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| 82 | } |
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| 83 | |||
| 84 | if (first <= last) { |
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| 85 | if ((last - first) + 1 < len) { |
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| 86 | /* |
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| 87 | * The buffer cannot absorb the path. |
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| 88 | */ |
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| 89 | futex_up(&plb_futex); |
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| 90 | return ELIMIT; |
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| 91 | } |
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| 92 | } else { |
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| 93 | if (PLB_SIZE - ((first - last) + 1) < len) { |
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| 94 | /* |
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| 95 | * The buffer cannot absorb the path. |
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| 96 | */ |
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| 97 | futex_up(&plb_futex); |
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| 98 | return ELIMIT; |
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| 99 | } |
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| 100 | } |
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| 101 | |||
| 102 | /* |
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| 103 | * We know the first free index in PLB and we also know that there is |
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| 104 | * enough space in the buffer to hold our path. |
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| 105 | */ |
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| 106 | |||
| 107 | entry.index = first; |
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| 108 | entry.len = len; |
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| 109 | |||
| 110 | /* |
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| 111 | * Claim PLB space by inserting the entry into the PLB entry ring |
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| 112 | * buffer. |
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| 113 | */ |
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| 114 | list_append(&entry.plb_link, &plb_head); |
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| 115 | |||
| 116 | futex_up(&plb_futex); |
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| 117 | |||
| 118 | /* |
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| 119 | * Copy the path into PLB. |
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| 120 | */ |
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| 121 | size_t cnt1 = min(len, (PLB_SIZE - first) + 1); |
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| 122 | size_t cnt2 = len - cnt1; |
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| 123 | |||
| 124 | memcpy(&plb[first], path, cnt1); |
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| 125 | memcpy(plb, &path[cnt1], cnt2); |
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| 126 | |||
| 127 | ipc_call_t answer; |
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| 2546 | jermar | 128 | int phone = vfs_grab_phone(rootfs->fs_handle); |
| 129 | aid_t req = async_send_3(phone, VFS_LOOKUP, (ipcarg_t) first, |
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| 130 | (ipcarg_t) last, (ipcarg_t) rootfs->dev_handle, &answer); |
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| 131 | vfs_release_phone(phone); |
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| 2544 | jermar | 132 | |
| 133 | ipcarg_t rc; |
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| 134 | async_wait_for(req, &rc); |
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| 135 | |||
| 136 | futex_down(&plb_futex); |
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| 137 | list_remove(&entry.plb_link); |
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| 138 | futex_up(&plb_futex); |
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| 139 | |||
| 140 | if (rc == EOK) { |
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| 141 | result->fs_handle = (int) IPC_GET_ARG1(answer); |
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| 142 | result->dev_handle = (int) IPC_GET_ARG2(answer); |
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| 143 | result->index = (int) IPC_GET_ARG3(answer); |
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| 144 | } |
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| 145 | |||
| 146 | return rc; |
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| 2542 | jermar | 147 | } |
| 148 | |||
| 149 | /** |
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| 150 | * @} |
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| 151 | */ |