0,0 → 1,192 |
/* |
* 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 <stdarg.h> |
#include <bool.h> |
#include <futex.h> |
#include <libadt/list.h> |
#include <vfs/canonify.h> |
|
#define min(a, b) ((a) < (b) ? (a) : (b)) |
|
futex_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 = &rootfs; |
|
if (!root->fs_handle) |
return ENOENT; |
|
size_t len; |
path = canonify(path, &len); |
if (!path) |
return EINVAL; |
|
fs_index_t index = 0; |
if (lflag & L_LINK) { |
va_list ap; |
|
va_start(ap, altroot); |
index = va_arg(ap, fs_index_t); |
va_end(ap); |
} |
|
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_5(phone, VFS_LOOKUP, (ipcarg_t) first, |
(ipcarg_t) (first + len - 1) % PLB_SIZE, |
(ipcarg_t) root->dev_handle, (ipcarg_t) lflag, (ipcarg_t) index, |
&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. |
*/ |
memset(&plb[first], 0, cnt1); |
memset(plb, 0, cnt2); |
futex_up(&plb_futex); |
|
if ((rc == EOK) && result) { |
result->triplet.fs_handle = (fs_handle_t) IPC_GET_ARG1(answer); |
result->triplet.dev_handle = (dev_handle_t) IPC_GET_ARG2(answer); |
result->triplet.index = (fs_index_t) IPC_GET_ARG3(answer); |
result->size = (size_t) IPC_GET_ARG4(answer); |
result->lnkcnt = (unsigned) IPC_GET_ARG5(answer); |
} |
|
return rc; |
} |
|
/** |
* @} |
*/ |