/*
* Copyright (c) 2008 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup fs
* @{
*/
/**
* @file vfs_lookup.c
* @brief
*/
#include "vfs.h"
#include <ipc/ipc.h>
#include <async.h>
#include <errno.h>
#include <string.h>
#include <bool.h>
#include <futex.h>
#include <libadt/list.h>
#include <atomic.h>
#include <vfs/canonify.h>
#define min(a, b) ((a) < (b) ? (a) : (b))
atomic_t plb_futex = FUTEX_INITIALIZER;
link_t plb_head; /**< PLB entry ring buffer. */
uint8_t *plb = NULL;
/** Perform a path lookup.
*
* @param path Path to be resolved; it must be a NULL-terminated
* string.
* @param lflag Flags to be used during lookup.
* @param result Empty structure where the lookup result will be stored.
* Can be NULL.
* @param altroot If non-empty, will be used instead of rootfs as the root
* of the whole VFS tree.
*
* @return EOK on success or an error code from errno.h.
*/
int vfs_lookup_internal(char *path, int lflag, vfs_lookup_res_t *result,
vfs_pair_t *altroot)
{
vfs_pair_t *root;
if (altroot)
root = altroot;
else
root = (vfs_pair_t *) &rootfs;
if (!root->fs_handle)
return ENOENT;
size_t len;
path = canonify(path, &len);
if (!path)
return EINVAL;
futex_down(&plb_futex);
plb_entry_t entry;
link_initialize(&entry.plb_link);
entry.len = len;
off_t first; /* the first free index */
off_t last; /* the last free index */
if (list_empty(&plb_head)) {
first = 0;
last = PLB_SIZE - 1;
} else {
plb_entry_t *oldest = list_get_instance(plb_head.next,
plb_entry_t, plb_link);
plb_entry_t *newest = list_get_instance(plb_head.prev,
plb_entry_t, plb_link);
first = (newest->index + newest->len) % PLB_SIZE;
last = (oldest->index - 1) % PLB_SIZE;
}
if (first <= last) {
if ((last - first) + 1 < len) {
/*
* The buffer cannot absorb the path.
*/
futex_up(&plb_futex);
return ELIMIT;
}
} else {
if (PLB_SIZE - ((first - last) + 1) < len) {
/*
* The buffer cannot absorb the path.
*/
futex_up(&plb_futex);
return ELIMIT;
}
}
/*
* We know the first free index in PLB and we also know that there is
* enough space in the buffer to hold our path.
*/
entry.index = first;
entry.len = len;
/*
* Claim PLB space by inserting the entry into the PLB entry ring
* buffer.
*/
list_append(&entry.plb_link, &plb_head);
futex_up(&plb_futex);
/*
* Copy the path into PLB.
*/
size_t cnt1 = min(len, (PLB_SIZE - first) + 1);
size_t cnt2 = len - cnt1;
memcpy(&plb
[first
], path
, cnt1
); memcpy(plb
, &path
[cnt1
], cnt2
);
ipc_call_t answer;
int phone = vfs_grab_phone(root->fs_handle);
aid_t req = async_send_4(phone, VFS_LOOKUP, (ipcarg_t) first,
(ipcarg_t) (first + len - 1) % PLB_SIZE,
(ipcarg_t) root->dev_handle, (ipcarg_t) lflag, &answer);
vfs_release_phone(phone);
ipcarg_t rc;
async_wait_for(req, &rc);
futex_down(&plb_futex);
list_remove(&entry.plb_link);
/*
* Erasing the path from PLB will come handy for debugging purposes.
*/
futex_up(&plb_futex);
if ((rc == EOK) && result) {
result->triplet.fs_handle = (int) IPC_GET_ARG1(answer);
result->triplet.dev_handle = (int) IPC_GET_ARG2(answer);
result->triplet.index = (int) IPC_GET_ARG3(answer);
result->size = (size_t) IPC_GET_ARG4(answer);
result->lnkcnt = (unsigned) IPC_GET_ARG5(answer);
}
return rc;
}
/**
* @}
*/