Subversion Repositories HelenOS

Rev

Rev 2700 | Rev 2730 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
2698 jermar 1
/*
2
 * Copyright (c) 2008 Jakub Jermar
3
 * All rights reserved.
4
 *
5
 * Redistribution and use in source and binary forms, with or without
6
 * modification, are permitted provided that the following conditions
7
 * are met:
8
 *
9
 * - Redistributions of source code must retain the above copyright
10
 *   notice, this list of conditions and the following disclaimer.
11
 * - Redistributions in binary form must reproduce the above copyright
12
 *   notice, this list of conditions and the following disclaimer in the
13
 *   documentation and/or other materials provided with the distribution.
14
 * - The name of the author may not be used to endorse or promote products
15
 *   derived from this software without specific prior written permission.
16
 *
17
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
 */
28
 
29
/** @addtogroup fs
30
 * @{
31
 */
32
 
33
/**
34
 * @file    vfs_lookup.c
35
 * @brief
36
 */
37
 
38
#include <ipc/ipc.h>
39
#include <async.h>
40
#include <errno.h>
41
#include <string.h>
42
#include <bool.h>
43
#include <futex.h>
44
#include <libadt/list.h>
45
#include <atomic.h>
46
#include "vfs.h"
47
 
48
#define min(a, b)   ((a) < (b) ? (a) : (b))
49
 
50
atomic_t plb_futex = FUTEX_INITIALIZER;
51
link_t plb_head;    /**< PLB entry ring buffer. */
52
uint8_t *plb = NULL;
53
 
54
/** Perform a path lookup.
55
 *
56
 * @param path      Path to be resolved; it needn't be an ASCIIZ string.
57
 * @param len       Number of path characters pointed by path.
2700 jermar 58
 * @param lflag     Flags to be used during lookup.
2698 jermar 59
 * @param result    Empty structure where the lookup result will be stored.
2707 jermar 60
 *          Can be NULL.
2698 jermar 61
 * @param altroot   If non-empty, will be used instead of rootfs as the root
62
 *          of the whole VFS tree.
63
 *
64
 * @return      EOK on success or an error code from errno.h.
65
 */
2700 jermar 66
int vfs_lookup_internal(char *path, size_t len, int lflag,
67
    vfs_lookup_res_t *result, vfs_pair_t *altroot)
2698 jermar 68
{
69
    vfs_pair_t *root;
70
 
71
    if (!len)
72
        return EINVAL;
73
 
74
    if (altroot)
75
        root = altroot;
76
    else
77
        root = (vfs_pair_t *) &rootfs;
78
 
79
    if (!root->fs_handle)
80
        return ENOENT;
81
 
82
    futex_down(&plb_futex);
83
 
84
    plb_entry_t entry;
85
    link_initialize(&entry.plb_link);
86
    entry.len = len;
87
 
88
    off_t first;    /* the first free index */
89
    off_t last; /* the last free index */
90
 
91
    if (list_empty(&plb_head)) {
92
        first = 0;
93
        last = PLB_SIZE - 1;
94
    } else {
95
        plb_entry_t *oldest = list_get_instance(plb_head.next,
96
            plb_entry_t, plb_link);
97
        plb_entry_t *newest = list_get_instance(plb_head.prev,
98
            plb_entry_t, plb_link);
99
 
100
        first = (newest->index + newest->len) % PLB_SIZE;
101
        last = (oldest->index - 1) % PLB_SIZE;
102
    }
103
 
104
    if (first <= last) {
105
        if ((last - first) + 1 < len) {
106
            /*
107
             * The buffer cannot absorb the path.
108
             */
109
            futex_up(&plb_futex);
110
            return ELIMIT;
111
        }
112
    } else {
113
        if (PLB_SIZE - ((first - last) + 1) < len) {
114
            /*
115
             * The buffer cannot absorb the path.
116
             */
117
            futex_up(&plb_futex);
118
            return ELIMIT;
119
        }
120
    }
121
 
122
    /*
123
     * We know the first free index in PLB and we also know that there is
124
     * enough space in the buffer to hold our path.
125
     */
126
 
127
    entry.index = first;
128
    entry.len = len;
129
 
130
    /*
131
     * Claim PLB space by inserting the entry into the PLB entry ring
132
     * buffer.
133
     */
134
    list_append(&entry.plb_link, &plb_head);
135
 
136
    futex_up(&plb_futex);
137
 
138
    /*
139
     * Copy the path into PLB.
140
     */
141
    size_t cnt1 = min(len, (PLB_SIZE - first) + 1);
142
    size_t cnt2 = len - cnt1;
143
 
144
    memcpy(&plb[first], path, cnt1);
145
    memcpy(plb, &path[cnt1], cnt2);
146
 
147
    ipc_call_t answer;
148
    int phone = vfs_grab_phone(root->fs_handle);
2700 jermar 149
    aid_t req = async_send_4(phone, VFS_LOOKUP, (ipcarg_t) first,
2698 jermar 150
        (ipcarg_t) (first + len - 1) % PLB_SIZE,
2700 jermar 151
        (ipcarg_t) root->dev_handle, (ipcarg_t) lflag, &answer);
2698 jermar 152
    vfs_release_phone(phone);
153
 
154
    ipcarg_t rc;
155
    async_wait_for(req, &rc);
156
 
157
    futex_down(&plb_futex);
158
    list_remove(&entry.plb_link);
159
    /*
160
     * Erasing the path from PLB will come handy for debugging purposes.
161
     */
162
    memset(&plb[first], 0, cnt1);
163
    memset(plb, 0, cnt2);
164
    futex_up(&plb_futex);
165
 
2707 jermar 166
    if ((rc == EOK) && result) {
2698 jermar 167
        result->triplet.fs_handle = (int) IPC_GET_ARG1(answer);
168
        result->triplet.dev_handle = (int) IPC_GET_ARG2(answer);
169
        result->triplet.index = (int) IPC_GET_ARG3(answer);
170
        result->size = (size_t) IPC_GET_ARG4(answer);
171
    }
172
 
173
    return rc;
174
}
175
 
176
/**
177
 * @}
178
 */