/* * 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 #include #include #include #include #include #include #include #include "vfs.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 needn't be an ASCIIZ string. * @param len Number of path characters pointed by path. * @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, size_t len, int lflag, vfs_lookup_res_t *result, vfs_pair_t *altroot) { vfs_pair_t *root; if (!len) return EINVAL; if (altroot) root = altroot; else root = (vfs_pair_t *) &rootfs; if (!root->fs_handle) return ENOENT; 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. */ memset(&plb[first], 0, cnt1); memset(plb, 0, cnt2); 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); } return rc; } /** * @} */