WebSVN – HelenOS – Diff – /branches/dynload/uspace/srv/vfs/vfs_ops.c


/*
 * 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_ops.c
 * @brief   Operations that VFS offers to its clients.
 */
 
#include "vfs.h"
#include <ipc/ipc.h>
#include <async.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <bool.h>
#include <futex.h>
#include <rwlock.h>
#include <libadt/list.h>
#include <unistd.h>
#include <ctype.h>
#include <fcntl.h>
#include <assert.h>
#include <vfs/canonify.h>
 
/* Forward declarations of static functions. */
static int vfs_truncate_internal(fs_handle_t, dev_handle_t, fs_index_t, size_t);
 
/**
 * This rwlock prevents the race between a triplet-to-VFS-node resolution and a
 * concurrent VFS operation which modifies the file system namespace.
 */
RWLOCK_INITIALIZE(namespace_rwlock);
 
futex_t rootfs_futex = FUTEX_INITIALIZER;
vfs_pair_t rootfs = {
    .fs_handle = 0,
    .dev_handle = 0
};
 
void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
{
    dev_handle_t dev_handle;
    vfs_node_t *mp_node = NULL;
    int rc;
    int phone;
 
    /*
     * We expect the library to do the device-name to device-handle
     * translation for us, thus the device handle will arrive as ARG1
     * in the request.
     */
    dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
 
    /*
     * For now, don't make use of ARG2 and ARG3, but they can be used to
     * carry mount options in the future.
     */
 
    ipc_callid_t callid;
    size_t size;
 
    /*
     * Now, we expect the client to send us data with the name of the file
     * system.
     */
    if (!ipc_data_write_receive(&callid, &size)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
 
    /*
     * Don't receive more than is necessary for storing a full file system
     * name.
     */
    if (size < 1 || size > FS_NAME_MAXLEN) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
 
    /* Deliver the file system name. */
    char fs_name[FS_NAME_MAXLEN + 1];
    (void) ipc_data_write_finalize(callid, fs_name, size);
    fs_name[size] = '\0';
   
    /*
     * Check if we know a file system with the same name as is in fs_name.
     * This will also give us its file system handle.
     */
    fs_handle_t fs_handle = fs_name_to_handle(fs_name, true);
    if (!fs_handle) {
        ipc_answer_0(rid, ENOENT);
        return;
    }
 
    /* Now, we want the client to send us the mount point. */
    if (!ipc_data_write_receive(&callid, &size)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
 
    /* Check whether size is reasonable wrt. the mount point. */
    if (size < 1 || size > MAX_PATH_LEN) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
    /* Allocate buffer for the mount point data being received. */
    uint8_t *buf;
    buf = malloc(size + 1);
    if (!buf) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
 
    /* Deliver the mount point. */
    (void) ipc_data_write_finalize(callid, buf, size);
    buf[size] = '\0';
 
    /* Resolve the path to the mountpoint. */
    vfs_lookup_res_t mp_res;
    futex_down(&rootfs_futex);
    if (rootfs.fs_handle) {
        /* We already have the root FS. */
        rwlock_write_lock(&namespace_rwlock);
        if ((size == 1) && (buf[0] == '/')) {
            /* Trying to mount root FS over root FS */
            rwlock_write_unlock(&namespace_rwlock);
            futex_up(&rootfs_futex);
            free(buf);
            ipc_answer_0(rid, EBUSY);
            return;
        }
        rc = vfs_lookup_internal(buf, L_DIRECTORY, &mp_res, NULL);
        if (rc != EOK) {
            /* The lookup failed for some reason. */
            rwlock_write_unlock(&namespace_rwlock);
            futex_up(&rootfs_futex);
            free(buf);
            ipc_answer_0(rid, rc);
            return;
        }
        mp_node = vfs_node_get(&mp_res);
        if (!mp_node) {
            rwlock_write_unlock(&namespace_rwlock);
            futex_up(&rootfs_futex);
            free(buf);
            ipc_answer_0(rid, ENOMEM);
            return;
        }
        /*
         * Now we hold a reference to mp_node.
         * It will be dropped upon the corresponding VFS_UNMOUNT.
         * This prevents the mount point from being deleted.
         */
        rwlock_write_unlock(&namespace_rwlock);
    } else {
        /* We still don't have the root file system mounted. */
        if ((size == 1) && (buf[0] == '/')) {
            /*
             * For this simple, but important case,
             * we are almost done.
             */
            free(buf);
           
            /* Tell the mountee that it is being mounted. */
            phone = vfs_grab_phone(fs_handle);
            rc = async_req_1_0(phone, VFS_MOUNTED,
                (ipcarg_t) dev_handle);
            vfs_release_phone(phone);
 
            if (rc == EOK) {
                rootfs.fs_handle = fs_handle;
                rootfs.dev_handle = dev_handle;
            }
 
            futex_up(&rootfs_futex);
            ipc_answer_0(rid, rc);
            return;
        } else {
            /*
             * We can't resolve this without the root filesystem
             * being mounted first.
             */
            futex_up(&rootfs_futex);
            free(buf);
            ipc_answer_0(rid, ENOENT);
            return;
        }
    }
    futex_up(&rootfs_futex);
   
    free(buf);  /* The buffer is not needed anymore. */
   
    /*
     * At this point, we have all necessary pieces: file system and device
     * handles, and we know the mount point VFS node.
     */
 
    phone = vfs_grab_phone(mp_res.triplet.fs_handle);
    rc = async_req_4_0(phone, VFS_MOUNT,
        (ipcarg_t) mp_res.triplet.dev_handle,
        (ipcarg_t) mp_res.triplet.index,
        (ipcarg_t) fs_handle,
        (ipcarg_t) dev_handle);
    vfs_release_phone(phone);
 
    if (rc != EOK) {
        /* Mount failed, drop reference to mp_node. */
        if (mp_node)
            vfs_node_put(mp_node);
    }
   
    ipc_answer_0(rid, rc);
}
 
void vfs_open(ipc_callid_t rid, ipc_call_t *request)
{
    if (!vfs_files_init()) {
        ipc_answer_0(rid, ENOMEM);
        return;
    }
 
    /*
     * The POSIX interface is open(path, oflag, mode).
     * We can receive oflags and mode along with the VFS_OPEN call; the path
     * will need to arrive in another call.
     *
     * We also receive one private, non-POSIX set of flags called lflag
     * used to pass information to vfs_lookup_internal().
     */
    int lflag = IPC_GET_ARG1(*request);
    int oflag = IPC_GET_ARG2(*request);
    int mode = IPC_GET_ARG3(*request);
    size_t len;
 
    if (oflag & O_CREAT)
        lflag |= L_CREATE;
    if (oflag & O_EXCL)
        lflag |= L_EXCLUSIVE;
 
    ipc_callid_t callid;
 
    if (!ipc_data_write_receive(&callid, &len)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
    char *path = malloc(len + 1);
    if (!path) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
    int rc;
    if ((rc = ipc_data_write_finalize(callid, path, len))) {
        ipc_answer_0(rid, rc);
        free(path);
        return;
    }
    path[len] = '\0';
   
    /*
     * Avoid the race condition in which the file can be deleted before we
     * find/create-and-lock the VFS node corresponding to the looked-up
     * triplet.
     */
    if (lflag & L_CREATE)
        rwlock_write_lock(&namespace_rwlock);
    else
        rwlock_read_lock(&namespace_rwlock);
 
    /* The path is now populated and we can call vfs_lookup_internal(). */
    vfs_lookup_res_t lr;
    rc = vfs_lookup_internal(path, lflag, &lr, NULL);
    if (rc) {
        if (lflag & L_CREATE)
            rwlock_write_unlock(&namespace_rwlock);
        else
            rwlock_read_unlock(&namespace_rwlock);
        ipc_answer_0(rid, rc);
        free(path);
        return;
    }
 
    /* Path is no longer needed. */
    free(path);
 
    vfs_node_t *node = vfs_node_get(&lr);
    if (lflag & L_CREATE)
        rwlock_write_unlock(&namespace_rwlock);
    else
        rwlock_read_unlock(&namespace_rwlock);
 
    /* Truncate the file if requested and if necessary. */
    if (oflag & O_TRUNC) {
        rwlock_write_lock(&node->contents_rwlock);
        if (node->size) {
            rc = vfs_truncate_internal(node->fs_handle,
                node->dev_handle, node->index, 0);
            if (rc) {
                rwlock_write_unlock(&node->contents_rwlock);
                vfs_node_put(node);
                ipc_answer_0(rid, rc);
                return;
            }
            node->size = 0;
        }
        rwlock_write_unlock(&node->contents_rwlock);
    }
 
    /*
     * Get ourselves a file descriptor and the corresponding vfs_file_t
     * structure.
     */
    int fd = vfs_fd_alloc();
    if (fd < 0) {
        vfs_node_put(node);
        ipc_answer_0(rid, fd);
        return;
    }
    vfs_file_t *file = vfs_file_get(fd);
    file->node = node;
    if (oflag & O_APPEND)
        file->append = true;
 
    /*
     * The following increase in reference count is for the fact that the
     * file is being opened and that a file structure is pointing to it.
     * It is necessary so that the file will not disappear when
     * vfs_node_put() is called. The reference will be dropped by the
     * respective VFS_CLOSE.
     */
    vfs_node_addref(node);
    vfs_node_put(node);
 
    /* Success! Return the new file descriptor to the client. */
    ipc_answer_1(rid, EOK, fd);
}
 
void vfs_close(ipc_callid_t rid, ipc_call_t *request)
{
    int fd = IPC_GET_ARG1(*request);
 
 
 
 
    int rc = vfs_fd_free(fd);
    ipc_answer_0(rid, rc);
}
 
static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
{
 
    /*
     * The following code strongly depends on the fact that the files data
     * structure can be only accessed by a single fibril and all file
     * operations are serialized (i.e. the reads and writes cannot
     * interleave and a file cannot be closed while it is being read).
     *
     * Additional synchronization needs to be added once the table of
     * open files supports parallel access!
     */
 
    int fd = IPC_GET_ARG1(*request);
   
    /* Lookup the file structure corresponding to the file descriptor. */
    vfs_file_t *file = vfs_file_get(fd);
    if (!file) {
        ipc_answer_0(rid, ENOENT);
        return;
    }
   
    /*
     * Now we need to receive a call with client's
     * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
     */
    ipc_callid_t callid;
    int res;
    if (read)
        res = ipc_data_read_receive(&callid, NULL);
    else
        res = ipc_data_write_receive(&callid, NULL);
    if (!res) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
   
    /*
     * Lock the open file structure so that no other thread can manipulate
     * the same open file at a time.
     */
    futex_down(&file->lock);
   
    /*
     * Lock the file's node so that no other client can read/write to it at
     * the same time.
     */
    if (read)
        rwlock_read_lock(&file->node->contents_rwlock);
    else
        rwlock_write_lock(&file->node->contents_rwlock);
   
    int fs_phone = vfs_grab_phone(file->node->fs_handle);  
   
    /* Make a VFS_READ/VFS_WRITE request at the destination FS server. */
    aid_t msg;
    ipc_call_t answer;
    if (!read && file->append)
        file->pos = file->node->size;
    msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
        file->node->dev_handle, file->node->index, file->pos, &answer);
   
    /*
     * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
     * destination FS server. The call will be routed as if sent by
     * ourselves. Note that call arguments are immutable in this case so we
     * don't have to bother.
     */
    ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
   
    vfs_release_phone(fs_phone);
   
    /* Wait for reply from the FS server. */
    ipcarg_t rc;
    async_wait_for(msg, &rc);
    size_t bytes = IPC_GET_ARG1(answer);
   
    /* Unlock the VFS node. */
    if (read)
        rwlock_read_unlock(&file->node->contents_rwlock);
    else {
        /* Update the cached version of node's size. */
        if (rc == EOK)
            file->node->size = IPC_GET_ARG2(answer);
        rwlock_write_unlock(&file->node->contents_rwlock);
    }
   
    /* Update the position pointer and unlock the open file. */
    if (rc == EOK)
        file->pos += bytes;
    futex_up(&file->lock);
   
    /*
     * FS server's reply is the final result of the whole operation we
     * return to the client.
     */
    ipc_answer_1(rid, rc, bytes);
}
 
void vfs_read(ipc_callid_t rid, ipc_call_t *request)
{
    vfs_rdwr(rid, request, true);
}
 
void vfs_write(ipc_callid_t rid, ipc_call_t *request)
{
    vfs_rdwr(rid, request, false);
}
 
void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
{
    int fd = (int) IPC_GET_ARG1(*request);
    off_t off = (off_t) IPC_GET_ARG2(*request);
    int whence = (int) IPC_GET_ARG3(*request);
 
 
    /* Lookup the file structure corresponding to the file descriptor. */
    vfs_file_t *file = vfs_file_get(fd);
    if (!file) {
        ipc_answer_0(rid, ENOENT);
        return;
    }
 
    off_t newpos;
    futex_down(&file->lock);
    if (whence == SEEK_SET) {
        file->pos = off;
        futex_up(&file->lock);
        ipc_answer_1(rid, EOK, off);
        return;
    }
    if (whence == SEEK_CUR) {
        if (file->pos + off < file->pos) {
            futex_up(&file->lock);
            ipc_answer_0(rid, EOVERFLOW);
            return;
        }
        file->pos += off;
        newpos = file->pos;
        futex_up(&file->lock);
        ipc_answer_1(rid, EOK, newpos);
        return;
    }
    if (whence == SEEK_END) {
        rwlock_read_lock(&file->node->contents_rwlock);
        size_t size = file->node->size;
        rwlock_read_unlock(&file->node->contents_rwlock);
        if (size + off < size) {
            futex_up(&file->lock);
            ipc_answer_0(rid, EOVERFLOW);
            return;
        }
        newpos = size + off;
        futex_up(&file->lock);
        ipc_answer_1(rid, EOK, newpos);
        return;
    }
    futex_up(&file->lock);
    ipc_answer_0(rid, EINVAL);
}
 
int
vfs_truncate_internal(fs_handle_t fs_handle, dev_handle_t dev_handle,
    fs_index_t index, size_t size)
{
    ipcarg_t rc;
    int fs_phone;
   
    fs_phone = vfs_grab_phone(fs_handle);
    rc = async_req_3_0(fs_phone, VFS_TRUNCATE, (ipcarg_t)dev_handle,
        (ipcarg_t)index, (ipcarg_t)size);
    vfs_release_phone(fs_phone);
    return (int)rc;
}
 
void vfs_truncate(ipc_callid_t rid, ipc_call_t *request)
{
    int fd = IPC_GET_ARG1(*request);
    size_t size = IPC_GET_ARG2(*request);
    int rc;
 
    vfs_file_t *file = vfs_file_get(fd);
    if (!file) {
        ipc_answer_0(rid, ENOENT);
        return;
    }
    futex_down(&file->lock);
 
    rwlock_write_lock(&file->node->contents_rwlock);
    rc = vfs_truncate_internal(file->node->fs_handle,
        file->node->dev_handle, file->node->index, size);
    if (rc == EOK)
        file->node->size = size;
    rwlock_write_unlock(&file->node->contents_rwlock);
 
    futex_up(&file->lock);
    ipc_answer_0(rid, (ipcarg_t)rc);
}
 
void vfs_mkdir(ipc_callid_t rid, ipc_call_t *request)
{
    int mode = IPC_GET_ARG1(*request);
 
    size_t len;
    ipc_callid_t callid;
 
    if (!ipc_data_write_receive(&callid, &len)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
    char *path = malloc(len + 1);
    if (!path) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
    int rc;
    if ((rc = ipc_data_write_finalize(callid, path, len))) {
        ipc_answer_0(rid, rc);
        free(path);
        return;
    }
    path[len] = '\0';
   
    rwlock_write_lock(&namespace_rwlock);
    int lflag = L_DIRECTORY | L_CREATE | L_EXCLUSIVE;
    rc = vfs_lookup_internal(path, lflag, NULL, NULL);
    rwlock_write_unlock(&namespace_rwlock);
    free(path);
    ipc_answer_0(rid, rc);
}
 
void vfs_unlink(ipc_callid_t rid, ipc_call_t *request)
{
    int lflag = IPC_GET_ARG1(*request);
 
    size_t len;
    ipc_callid_t callid;
 
    if (!ipc_data_write_receive(&callid, &len)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
    char *path = malloc(len + 1);
    if (!path) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
    int rc;
    if ((rc = ipc_data_write_finalize(callid, path, len))) {
        ipc_answer_0(rid, rc);
        free(path);
        return;
    }
    path[len] = '\0';
   
    rwlock_write_lock(&namespace_rwlock);
    lflag &= L_DIRECTORY;   /* sanitize lflag */
    vfs_lookup_res_t lr;
    rc = vfs_lookup_internal(path, lflag | L_UNLINK, &lr, NULL);
    free(path);
    if (rc != EOK) {
        rwlock_write_unlock(&namespace_rwlock);
        ipc_answer_0(rid, rc);
        return;
    }
 
    /*
     * The name has already been unlinked by vfs_lookup_internal().
     * We have to get and put the VFS node to ensure that it is
     * VFS_DESTROY'ed after the last reference to it is dropped.
     */
    vfs_node_t *node = vfs_node_get(&lr);
    futex_down(&nodes_futex);
    node->lnkcnt--;
    futex_up(&nodes_futex);
    rwlock_write_unlock(&namespace_rwlock);
    vfs_node_put(node);
    ipc_answer_0(rid, EOK);
}
 
void vfs_rename(ipc_callid_t rid, ipc_call_t *request)
{
    size_t len;
    ipc_callid_t callid;
    int rc;
 
    /* Retrieve the old path. */
    if (!ipc_data_write_receive(&callid, &len)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
    char *old = malloc(len + 1);
    if (!old) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
    if ((rc = ipc_data_write_finalize(callid, old, len))) {
        ipc_answer_0(rid, rc);
        free(old);
        return;
    }
    old[len] = '\0';
   
    /* Retrieve the new path. */
    if (!ipc_data_write_receive(&callid, &len)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        free(old);
        return;
    }
    char *new = malloc(len + 1);
    if (!new) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        free(old);
        return;
    }
    if ((rc = ipc_data_write_finalize(callid, new, len))) {
        ipc_answer_0(rid, rc);
        free(old);
        free(new);
        return;
    }
    new[len] = '\0';
 
    char *oldc = canonify(old, &len);
    char *newc = canonify(new, NULL);
    if (!oldc || !newc) {
        ipc_answer_0(rid, EINVAL);
        free(old);
        free(new);
        return;
    }
    if (!strncmp(newc, oldc, len)) {
        /* oldc is a prefix of newc */
        ipc_answer_0(rid, EINVAL);
        free(old);
        free(new);
        return;
    }
   
    vfs_lookup_res_t old_lr;
    vfs_lookup_res_t new_lr;
    vfs_lookup_res_t new_par_lr;
    rwlock_write_lock(&namespace_rwlock);
    /* Lookup the node belonging to the old file name. */
    rc = vfs_lookup_internal(oldc, L_NONE, &old_lr, NULL);
    if (rc != EOK) {
        rwlock_write_unlock(&namespace_rwlock);
        ipc_answer_0(rid, rc);
        free(old);
        free(new);
        return;
    }
    vfs_node_t *old_node = vfs_node_get(&old_lr);
    if (!old_node) {
        rwlock_write_unlock(&namespace_rwlock);
        ipc_answer_0(rid, ENOMEM);
        free(old);
        free(new);
        return;
    }
    /* Lookup parent of the new file name. */
    rc = vfs_lookup_internal(newc, L_PARENT, &new_par_lr, NULL);
    if (rc != EOK) {
        rwlock_write_unlock(&namespace_rwlock);
        ipc_answer_0(rid, rc);
        free(old);
        free(new);
        return;
    }
    /* Check whether linking to the same file system instance. */
    if ((old_node->fs_handle != new_par_lr.triplet.fs_handle) ||
        (old_node->dev_handle != new_par_lr.triplet.dev_handle)) {
        rwlock_write_unlock(&namespace_rwlock);
        ipc_answer_0(rid, EXDEV);   /* different file systems */
        free(old);
        free(new);
        return;
    }
    /* Destroy the old link for the new name. */
    vfs_node_t *new_node = NULL;
    rc = vfs_lookup_internal(newc, L_UNLINK, &new_lr, NULL);
    switch (rc) {
    case ENOENT:
        /* simply not in our way */
        break;
    case EOK:
        new_node = vfs_node_get(&new_lr);
        if (!new_node) {
            rwlock_write_unlock(&namespace_rwlock);
            ipc_answer_0(rid, ENOMEM);
            free(old);
            free(new);
            return;
        }
        futex_down(&nodes_futex);
        new_node->lnkcnt--;
        futex_up(&nodes_futex);
        break;
    default:
        rwlock_write_unlock(&namespace_rwlock);
        ipc_answer_0(rid, ENOTEMPTY);
        free(old);
        free(new);
        return;
    }
    /* Create the new link for the new name. */
    rc = vfs_lookup_internal(newc, L_LINK, NULL, NULL, old_node->index);
    if (rc != EOK) {
        rwlock_write_unlock(&namespace_rwlock);
        if (new_node)
            vfs_node_put(new_node);
        ipc_answer_0(rid, rc);
        free(old);
        free(new);
        return;
    }
    futex_down(&nodes_futex);
    old_node->lnkcnt++;
    futex_up(&nodes_futex);
    /* Destroy the link for the old name. */
    rc = vfs_lookup_internal(oldc, L_UNLINK, NULL, NULL);
    if (rc != EOK) {
        rwlock_write_unlock(&namespace_rwlock);
        vfs_node_put(old_node);
        if (new_node)
            vfs_node_put(new_node);
        ipc_answer_0(rid, rc);
        free(old);
        free(new);
        return;
    }
    futex_down(&nodes_futex);
    old_node->lnkcnt--;
    futex_up(&nodes_futex);
    rwlock_write_unlock(&namespace_rwlock);
    vfs_node_put(old_node);
    if (new_node)
        vfs_node_put(new_node);
    free(old);
    free(new);
    ipc_answer_0(rid, EOK);
}
 
/**
 * @}
 */
 

Rev 3153	Rev 3219
1	/*	1	/*
2	* Copyright (c) 2008 Jakub Jermar	2	* Copyright (c) 2008 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	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	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.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	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	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	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	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	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	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.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/** @addtogroup fs	29	/** @addtogroup fs
30	* @{	30	* @{
31	*/	31	*/
32		32
33	/**	33	/**
34	* @file vfs_ops.c	34	* @file vfs_ops.c
35	* @brief Operations that VFS offers to its clients.	35	* @brief Operations that VFS offers to its clients.
36	*/	36	*/
37		37
38	#include "vfs.h"	38	#include "vfs.h"
39	#include <ipc/ipc.h>	39	#include <ipc/ipc.h>
40	#include <async.h>	40	#include <async.h>
41	#include <errno.h>	41	#include <errno.h>
42	#include <stdio.h>	42	#include <stdio.h>
43	#include <stdlib.h>	43	#include <stdlib.h>
44	#include <string.h>	44	#include <string.h>
45	#include <bool.h>	45	#include <bool.h>
46	#include <futex.h>	46	#include <futex.h>
47	#include <rwlock.h>	47	#include <rwlock.h>
48	#include <libadt/list.h>	48	#include <libadt/list.h>
49	#include <unistd.h>	49	#include <unistd.h>
50	#include <ctype.h>	50	#include <ctype.h>
51	#include <fcntl.h>	51	#include <fcntl.h>
52	#include <assert.h>	52	#include <assert.h>
53	#include <vfs/canonify.h>	53	#include <vfs/canonify.h>
54		54
55	/* Forward declarations of static functions. */	55	/* Forward declarations of static functions. */
56	static int vfs_truncate_internal(fs_handle_t, dev_handle_t, fs_index_t, size_t);	56	static int vfs_truncate_internal(fs_handle_t, dev_handle_t, fs_index_t, size_t);
57		57
58	/**	58	/**
59	* This rwlock prevents the race between a triplet-to-VFS-node resolution and a	59	* This rwlock prevents the race between a triplet-to-VFS-node resolution and a
60	* concurrent VFS operation which modifies the file system namespace.	60	* concurrent VFS operation which modifies the file system namespace.
61	*/	61	*/
62	RWLOCK_INITIALIZE(namespace_rwlock);	62	RWLOCK_INITIALIZE(namespace_rwlock);
63		63
64	futex_t rootfs_futex = FUTEX_INITIALIZER;	64	futex_t rootfs_futex = FUTEX_INITIALIZER;
65	vfs_pair_t rootfs = {	65	vfs_pair_t rootfs = {
66	.fs_handle = 0,	66	.fs_handle = 0,
67	.dev_handle = 0	67	.dev_handle = 0
68	};	68	};
69		69
70	void vfs_mount(ipc_callid_t rid, ipc_call_t *request)	70	void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
71	{	71	{
72	dev_handle_t dev_handle;	72	dev_handle_t dev_handle;
73	vfs_node_t *mp_node = NULL;	73	vfs_node_t *mp_node = NULL;
74	int rc;	74	int rc;
75	int phone;	75	int phone;
76		76
77	/*	77	/*
78	* We expect the library to do the device-name to device-handle	78	* We expect the library to do the device-name to device-handle
79	* translation for us, thus the device handle will arrive as ARG1	79	* translation for us, thus the device handle will arrive as ARG1
80	* in the request.	80	* in the request.
81	*/	81	*/
82	dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);	82	dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
83		83
84	/*	84	/*
85	* For now, don't make use of ARG2 and ARG3, but they can be used to	85	* For now, don't make use of ARG2 and ARG3, but they can be used to
86	* carry mount options in the future.	86	* carry mount options in the future.
87	*/	87	*/
88		88
89	ipc_callid_t callid;	89	ipc_callid_t callid;
90	size_t size;	90	size_t size;
91		91
92	/*	92	/*
93	* Now, we expect the client to send us data with the name of the file	93	* Now, we expect the client to send us data with the name of the file
94	* system.	94	* system.
95	*/	95	*/
96	if (!ipc_data_write_receive(&callid, &size)) {	96	if (!ipc_data_write_receive(&callid, &size)) {
97	ipc_answer_0(callid, EINVAL);	97	ipc_answer_0(callid, EINVAL);
98	ipc_answer_0(rid, EINVAL);	98	ipc_answer_0(rid, EINVAL);
99	return;	99	return;
100	}	100	}
101		101
102	/*	102	/*
103	* Don't receive more than is necessary for storing a full file system	103	* Don't receive more than is necessary for storing a full file system
104	* name.	104	* name.
105	*/	105	*/
106	if (size < 1 \|\| size > FS_NAME_MAXLEN) {	106	if (size < 1 \|\| size > FS_NAME_MAXLEN) {
107	ipc_answer_0(callid, EINVAL);	107	ipc_answer_0(callid, EINVAL);
108	ipc_answer_0(rid, EINVAL);	108	ipc_answer_0(rid, EINVAL);
109	return;	109	return;
110	}	110	}
111		111
112	/* Deliver the file system name. */	112	/* Deliver the file system name. */
113	char fs_name[FS_NAME_MAXLEN + 1];	113	char fs_name[FS_NAME_MAXLEN + 1];
114	(void) ipc_data_write_finalize(callid, fs_name, size);	114	(void) ipc_data_write_finalize(callid, fs_name, size);
115	fs_name[size] = '\0';	115	fs_name[size] = '\0';
116		116
117	/*	117	/*
118	* Check if we know a file system with the same name as is in fs_name.	118	* Check if we know a file system with the same name as is in fs_name.
119	* This will also give us its file system handle.	119	* This will also give us its file system handle.
120	*/	120	*/
121	fs_handle_t fs_handle = fs_name_to_handle(fs_name, true);	121	fs_handle_t fs_handle = fs_name_to_handle(fs_name, true);
122	if (!fs_handle) {	122	if (!fs_handle) {
123	ipc_answer_0(rid, ENOENT);	123	ipc_answer_0(rid, ENOENT);
124	return;	124	return;
125	}	125	}
126		126
127	/* Now, we want the client to send us the mount point. */	127	/* Now, we want the client to send us the mount point. */
128	if (!ipc_data_write_receive(&callid, &size)) {	128	if (!ipc_data_write_receive(&callid, &size)) {
129	ipc_answer_0(callid, EINVAL);	129	ipc_answer_0(callid, EINVAL);
130	ipc_answer_0(rid, EINVAL);	130	ipc_answer_0(rid, EINVAL);
131	return;	131	return;
132	}	132	}
133		133
134	/* Check whether size is reasonable wrt. the mount point. */	134	/* Check whether size is reasonable wrt. the mount point. */
135	if (size < 1 \|\| size > MAX_PATH_LEN) {	135	if (size < 1 \|\| size > MAX_PATH_LEN) {
136	ipc_answer_0(callid, EINVAL);	136	ipc_answer_0(callid, EINVAL);
137	ipc_answer_0(rid, EINVAL);	137	ipc_answer_0(rid, EINVAL);
138	return;	138	return;
139	}	139	}
140	/* Allocate buffer for the mount point data being received. */	140	/* Allocate buffer for the mount point data being received. */
141	uint8_t *buf;	141	uint8_t *buf;
142	buf = malloc(size + 1);	142	buf = malloc(size + 1);
143	if (!buf) {	143	if (!buf) {
144	ipc_answer_0(callid, ENOMEM);	144	ipc_answer_0(callid, ENOMEM);
145	ipc_answer_0(rid, ENOMEM);	145	ipc_answer_0(rid, ENOMEM);
146	return;	146	return;
147	}	147	}
148		148
149	/* Deliver the mount point. */	149	/* Deliver the mount point. */
150	(void) ipc_data_write_finalize(callid, buf, size);	150	(void) ipc_data_write_finalize(callid, buf, size);
151	buf[size] = '\0';	151	buf[size] = '\0';
152		152
153	/* Resolve the path to the mountpoint. */	153	/* Resolve the path to the mountpoint. */
154	vfs_lookup_res_t mp_res;	154	vfs_lookup_res_t mp_res;
155	futex_down(&rootfs_futex);	155	futex_down(&rootfs_futex);
156	if (rootfs.fs_handle) {	156	if (rootfs.fs_handle) {
157	/* We already have the root FS. */	157	/* We already have the root FS. */
158	rwlock_write_lock(&namespace_rwlock);	158	rwlock_write_lock(&namespace_rwlock);
159	if ((size == 1) && (buf[0] == '/')) {	159	if ((size == 1) && (buf[0] == '/')) {
160	/* Trying to mount root FS over root FS */	160	/* Trying to mount root FS over root FS */
161	rwlock_write_unlock(&namespace_rwlock);	161	rwlock_write_unlock(&namespace_rwlock);
162	futex_up(&rootfs_futex);	162	futex_up(&rootfs_futex);
163	free(buf);	163	free(buf);
164	ipc_answer_0(rid, EBUSY);	164	ipc_answer_0(rid, EBUSY);
165	return;	165	return;
166	}	166	}
167	rc = vfs_lookup_internal(buf, L_DIRECTORY, &mp_res, NULL);	167	rc = vfs_lookup_internal(buf, L_DIRECTORY, &mp_res, NULL);
168	if (rc != EOK) {	168	if (rc != EOK) {
169	/* The lookup failed for some reason. */	169	/* The lookup failed for some reason. */
170	rwlock_write_unlock(&namespace_rwlock);	170	rwlock_write_unlock(&namespace_rwlock);
171	futex_up(&rootfs_futex);	171	futex_up(&rootfs_futex);
172	free(buf);	172	free(buf);
173	ipc_answer_0(rid, rc);	173	ipc_answer_0(rid, rc);
174	return;	174	return;
175	}	175	}
176	mp_node = vfs_node_get(&mp_res);	176	mp_node = vfs_node_get(&mp_res);
177	if (!mp_node) {	177	if (!mp_node) {
178	rwlock_write_unlock(&namespace_rwlock);	178	rwlock_write_unlock(&namespace_rwlock);
179	futex_up(&rootfs_futex);	179	futex_up(&rootfs_futex);
180	free(buf);	180	free(buf);
181	ipc_answer_0(rid, ENOMEM);	181	ipc_answer_0(rid, ENOMEM);
182	return;	182	return;
183	}	183	}
184	/*	184	/*
185	* Now we hold a reference to mp_node.	185	* Now we hold a reference to mp_node.
186	* It will be dropped upon the corresponding VFS_UNMOUNT.	186	* It will be dropped upon the corresponding VFS_UNMOUNT.
187	* This prevents the mount point from being deleted.	187	* This prevents the mount point from being deleted.
188	*/	188	*/
189	rwlock_write_unlock(&namespace_rwlock);	189	rwlock_write_unlock(&namespace_rwlock);
190	} else {	190	} else {
191	/* We still don't have the root file system mounted. */	191	/* We still don't have the root file system mounted. */
192	if ((size == 1) && (buf[0] == '/')) {	192	if ((size == 1) && (buf[0] == '/')) {
193	/*	193	/*
194	* For this simple, but important case,	194	* For this simple, but important case,
195	* we are almost done.	195	* we are almost done.
196	*/	196	*/
197	free(buf);	197	free(buf);
198		198
199	/* Tell the mountee that it is being mounted. */	199	/* Tell the mountee that it is being mounted. */
200	phone = vfs_grab_phone(fs_handle);	200	phone = vfs_grab_phone(fs_handle);
201	rc = async_req_1_0(phone, VFS_MOUNTED,	201	rc = async_req_1_0(phone, VFS_MOUNTED,
202	(ipcarg_t) dev_handle);	202	(ipcarg_t) dev_handle);
203	vfs_release_phone(phone);	203	vfs_release_phone(phone);
204		204
205	if (rc == EOK) {	205	if (rc == EOK) {
206	rootfs.fs_handle = fs_handle;	206	rootfs.fs_handle = fs_handle;
207	rootfs.dev_handle = dev_handle;	207	rootfs.dev_handle = dev_handle;
208	}	208	}
209		209
210	futex_up(&rootfs_futex);	210	futex_up(&rootfs_futex);
211	ipc_answer_0(rid, rc);	211	ipc_answer_0(rid, rc);
212	return;	212	return;
213	} else {	213	} else {
214	/*	214	/*
215	* We can't resolve this without the root filesystem	215	* We can't resolve this without the root filesystem
216	* being mounted first.	216	* being mounted first.
217	*/	217	*/
218	futex_up(&rootfs_futex);	218	futex_up(&rootfs_futex);
219	free(buf);	219	free(buf);
220	ipc_answer_0(rid, ENOENT);	220	ipc_answer_0(rid, ENOENT);
221	return;	221	return;
222	}	222	}
223	}	223	}
224	futex_up(&rootfs_futex);	224	futex_up(&rootfs_futex);
225		225
226	free(buf); /* The buffer is not needed anymore. */	226	free(buf); /* The buffer is not needed anymore. */
227		227
228	/*	228	/*
229	* At this point, we have all necessary pieces: file system and device	229	* At this point, we have all necessary pieces: file system and device
230	* handles, and we know the mount point VFS node.	230	* handles, and we know the mount point VFS node.
231	*/	231	*/
232		232
233	phone = vfs_grab_phone(mp_res.triplet.fs_handle);	233	phone = vfs_grab_phone(mp_res.triplet.fs_handle);
234	rc = async_req_4_0(phone, VFS_MOUNT,	234	rc = async_req_4_0(phone, VFS_MOUNT,
235	(ipcarg_t) mp_res.triplet.dev_handle,	235	(ipcarg_t) mp_res.triplet.dev_handle,
236	(ipcarg_t) mp_res.triplet.index,	236	(ipcarg_t) mp_res.triplet.index,
237	(ipcarg_t) fs_handle,	237	(ipcarg_t) fs_handle,
238	(ipcarg_t) dev_handle);	238	(ipcarg_t) dev_handle);
239	vfs_release_phone(phone);	239	vfs_release_phone(phone);
240		240
241	if (rc != EOK) {	241	if (rc != EOK) {
242	/* Mount failed, drop reference to mp_node. */	242	/* Mount failed, drop reference to mp_node. */
243	if (mp_node)	243	if (mp_node)
244	vfs_node_put(mp_node);	244	vfs_node_put(mp_node);
245	}	245	}
246		246
247	ipc_answer_0(rid, rc);	247	ipc_answer_0(rid, rc);
248	}	248	}
249		249
250	void vfs_open(ipc_callid_t rid, ipc_call_t *request)	250	void vfs_open(ipc_callid_t rid, ipc_call_t *request)
251	{	251	{
252	if (!vfs_files_init()) {	252	if (!vfs_files_init()) {
253	ipc_answer_0(rid, ENOMEM);	253	ipc_answer_0(rid, ENOMEM);
254	return;	254	return;
255	}	255	}
256		256
257	/*	257	/*
258	* The POSIX interface is open(path, oflag, mode).	258	* The POSIX interface is open(path, oflag, mode).
259	* We can receive oflags and mode along with the VFS_OPEN call; the path	259	* We can receive oflags and mode along with the VFS_OPEN call; the path
260	* will need to arrive in another call.	260	* will need to arrive in another call.
261	*	261	*
262	* We also receive one private, non-POSIX set of flags called lflag	262	* We also receive one private, non-POSIX set of flags called lflag
263	* used to pass information to vfs_lookup_internal().	263	* used to pass information to vfs_lookup_internal().
264	*/	264	*/
265	int lflag = IPC_GET_ARG1(*request);	265	int lflag = IPC_GET_ARG1(*request);
266	int oflag = IPC_GET_ARG2(*request);	266	int oflag = IPC_GET_ARG2(*request);
267	int mode = IPC_GET_ARG3(*request);	267	int mode = IPC_GET_ARG3(*request);
268	size_t len;	268	size_t len;
269		269
270	if (oflag & O_CREAT)	270	if (oflag & O_CREAT)
271	lflag \|= L_CREATE;	271	lflag \|= L_CREATE;
272	if (oflag & O_EXCL)	272	if (oflag & O_EXCL)
273	lflag \|= L_EXCLUSIVE;	273	lflag \|= L_EXCLUSIVE;
274		274
275	ipc_callid_t callid;	275	ipc_callid_t callid;
276		276
277	if (!ipc_data_write_receive(&callid, &len)) {	277	if (!ipc_data_write_receive(&callid, &len)) {
278	ipc_answer_0(callid, EINVAL);	278	ipc_answer_0(callid, EINVAL);
279	ipc_answer_0(rid, EINVAL);	279	ipc_answer_0(rid, EINVAL);
280	return;	280	return;
281	}	281	}
282	char *path = malloc(len + 1);	282	char *path = malloc(len + 1);
283	if (!path) {	283	if (!path) {
284	ipc_answer_0(callid, ENOMEM);	284	ipc_answer_0(callid, ENOMEM);
285	ipc_answer_0(rid, ENOMEM);	285	ipc_answer_0(rid, ENOMEM);
286	return;	286	return;
287	}	287	}
288	int rc;	288	int rc;
289	if ((rc = ipc_data_write_finalize(callid, path, len))) {	289	if ((rc = ipc_data_write_finalize(callid, path, len))) {
290	ipc_answer_0(rid, rc);	290	ipc_answer_0(rid, rc);
291	free(path);	291	free(path);
292	return;	292	return;
293	}	293	}
294	path[len] = '\0';	294	path[len] = '\0';
295		295
296	/*	296	/*
297	* Avoid the race condition in which the file can be deleted before we	297	* Avoid the race condition in which the file can be deleted before we
298	* find/create-and-lock the VFS node corresponding to the looked-up	298	* find/create-and-lock the VFS node corresponding to the looked-up
299	* triplet.	299	* triplet.
300	*/	300	*/
301	if (lflag & L_CREATE)	301	if (lflag & L_CREATE)
302	rwlock_write_lock(&namespace_rwlock);	302	rwlock_write_lock(&namespace_rwlock);
303	else	303	else
304	rwlock_read_lock(&namespace_rwlock);	304	rwlock_read_lock(&namespace_rwlock);
305		305
306	/* The path is now populated and we can call vfs_lookup_internal(). */	306	/* The path is now populated and we can call vfs_lookup_internal(). */
307	vfs_lookup_res_t lr;	307	vfs_lookup_res_t lr;
308	rc = vfs_lookup_internal(path, lflag, &lr, NULL);	308	rc = vfs_lookup_internal(path, lflag, &lr, NULL);
309	if (rc) {	309	if (rc) {
310	if (lflag & L_CREATE)	310	if (lflag & L_CREATE)
311	rwlock_write_unlock(&namespace_rwlock);	311	rwlock_write_unlock(&namespace_rwlock);
312	else	312	else
313	rwlock_read_unlock(&namespace_rwlock);	313	rwlock_read_unlock(&namespace_rwlock);
314	ipc_answer_0(rid, rc);	314	ipc_answer_0(rid, rc);
315	free(path);	315	free(path);
316	return;	316	return;
317	}	317	}
318		318
319	/* Path is no longer needed. */	319	/* Path is no longer needed. */
320	free(path);	320	free(path);
321		321
322	vfs_node_t *node = vfs_node_get(&lr);	322	vfs_node_t *node = vfs_node_get(&lr);
323	if (lflag & L_CREATE)	323	if (lflag & L_CREATE)
324	rwlock_write_unlock(&namespace_rwlock);	324	rwlock_write_unlock(&namespace_rwlock);
325	else	325	else
326	rwlock_read_unlock(&namespace_rwlock);	326	rwlock_read_unlock(&namespace_rwlock);
327		327
328	/* Truncate the file if requested and if necessary. */	328	/* Truncate the file if requested and if necessary. */
329	if (oflag & O_TRUNC) {	329	if (oflag & O_TRUNC) {
330	rwlock_write_lock(&node->contents_rwlock);	330	rwlock_write_lock(&node->contents_rwlock);
331	if (node->size) {	331	if (node->size) {
332	rc = vfs_truncate_internal(node->fs_handle,	332	rc = vfs_truncate_internal(node->fs_handle,
333	node->dev_handle, node->index, 0);	333	node->dev_handle, node->index, 0);
334	if (rc) {	334	if (rc) {
335	rwlock_write_unlock(&node->contents_rwlock);	335	rwlock_write_unlock(&node->contents_rwlock);
336	vfs_node_put(node);	336	vfs_node_put(node);
337	ipc_answer_0(rid, rc);	337	ipc_answer_0(rid, rc);
338	return;	338	return;
339	}	339	}
340	node->size = 0;	340	node->size = 0;
341	}	341	}
342	rwlock_write_unlock(&node->contents_rwlock);	342	rwlock_write_unlock(&node->contents_rwlock);
343	}	343	}
344		344
345	/*	345	/*
346	* Get ourselves a file descriptor and the corresponding vfs_file_t	346	* Get ourselves a file descriptor and the corresponding vfs_file_t
347	* structure.	347	* structure.
348	*/	348	*/
349	int fd = vfs_fd_alloc();	349	int fd = vfs_fd_alloc();
350	if (fd < 0) {	350	if (fd < 0) {
351	vfs_node_put(node);	351	vfs_node_put(node);
352	ipc_answer_0(rid, fd);	352	ipc_answer_0(rid, fd);
353	return;	353	return;
354	}	354	}
355	vfs_file_t *file = vfs_file_get(fd);	355	vfs_file_t *file = vfs_file_get(fd);
356	file->node = node;	356	file->node = node;
357	if (oflag & O_APPEND)	357	if (oflag & O_APPEND)
358	file->append = true;	358	file->append = true;
359		359
360	/*	360	/*
361	* The following increase in reference count is for the fact that the	361	* The following increase in reference count is for the fact that the
362	* file is being opened and that a file structure is pointing to it.	362	* file is being opened and that a file structure is pointing to it.
363	* It is necessary so that the file will not disappear when	363	* It is necessary so that the file will not disappear when
364	* vfs_node_put() is called. The reference will be dropped by the	364	* vfs_node_put() is called. The reference will be dropped by the
365	* respective VFS_CLOSE.	365	* respective VFS_CLOSE.
366	*/	366	*/
367	vfs_node_addref(node);	367	vfs_node_addref(node);
368	vfs_node_put(node);	368	vfs_node_put(node);
369		369
370	/* Success! Return the new file descriptor to the client. */	370	/* Success! Return the new file descriptor to the client. */
371	ipc_answer_1(rid, EOK, fd);	371	ipc_answer_1(rid, EOK, fd);
372	}	372	}
373		373
374	void vfs_close(ipc_callid_t rid, ipc_call_t *request)	374	void vfs_close(ipc_callid_t rid, ipc_call_t *request)
375	{	375	{
376	int fd = IPC_GET_ARG1(*request);	376	int fd = IPC_GET_ARG1(*request);
377	if (fd >= MAX_OPEN_FILES) {	-
378	ipc_answer_0(rid, EBADF);	-
379	return;	-
380	}	-
381	vfs_fd_free(fd);	377	int rc = vfs_fd_free(fd);
382	ipc_answer_0(rid, EOK);	378	ipc_answer_0(rid, rc);
383	}	379	}
384		380
385	static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)	381	static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
386	{	382	{
387		383
388	/*	384	/*
389	* The following code strongly depends on the fact that the files data	385	* The following code strongly depends on the fact that the files data
390	* structure can be only accessed by a single fibril and all file	386	* structure can be only accessed by a single fibril and all file
391	* operations are serialized (i.e. the reads and writes cannot	387	* operations are serialized (i.e. the reads and writes cannot
392	* interleave and a file cannot be closed while it is being read).	388	* interleave and a file cannot be closed while it is being read).
393	*	389	*
394	* Additional synchronization needs to be added once the table of	390	* Additional synchronization needs to be added once the table of
395	* open files supports parallel access!	391	* open files supports parallel access!
396	*/	392	*/
397		393
398	int fd = IPC_GET_ARG1(*request);	394	int fd = IPC_GET_ARG1(*request);
399		395
400	/* Lookup the file structure corresponding to the file descriptor. */	396	/* Lookup the file structure corresponding to the file descriptor. */
401	vfs_file_t *file = vfs_file_get(fd);	397	vfs_file_t *file = vfs_file_get(fd);
402	if (!file) {	398	if (!file) {
403	ipc_answer_0(rid, ENOENT);	399	ipc_answer_0(rid, ENOENT);
404	return;	400	return;
405	}	401	}
406		402
407	/*	403	/*
408	* Now we need to receive a call with client's	404	* Now we need to receive a call with client's
409	* IPC_M_DATA_READ/IPC_M_DATA_WRITE request.	405	* IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
410	*/	406	*/
411	ipc_callid_t callid;	407	ipc_callid_t callid;
412	int res;	408	int res;
413	if (read)	409	if (read)
414	res = ipc_data_read_receive(&callid, NULL);	410	res = ipc_data_read_receive(&callid, NULL);
415	else	411	else
416	res = ipc_data_write_receive(&callid, NULL);	412	res = ipc_data_write_receive(&callid, NULL);
417	if (!res) {	413	if (!res) {
418	ipc_answer_0(callid, EINVAL);	414	ipc_answer_0(callid, EINVAL);
419	ipc_answer_0(rid, EINVAL);	415	ipc_answer_0(rid, EINVAL);
420	return;	416	return;
421	}	417	}
422		418
423	/*	419	/*
424	* Lock the open file structure so that no other thread can manipulate	420	* Lock the open file structure so that no other thread can manipulate
425	* the same open file at a time.	421	* the same open file at a time.
426	*/	422	*/
427	futex_down(&file->lock);	423	futex_down(&file->lock);
428		424
429	/*	425	/*
430	* Lock the file's node so that no other client can read/write to it at	426	* Lock the file's node so that no other client can read/write to it at
431	* the same time.	427	* the same time.
432	*/	428	*/
433	if (read)	429	if (read)
434	rwlock_read_lock(&file->node->contents_rwlock);	430	rwlock_read_lock(&file->node->contents_rwlock);
435	else	431	else
436	rwlock_write_lock(&file->node->contents_rwlock);	432	rwlock_write_lock(&file->node->contents_rwlock);
437		433
438	int fs_phone = vfs_grab_phone(file->node->fs_handle);	434	int fs_phone = vfs_grab_phone(file->node->fs_handle);
439		435
440	/* Make a VFS_READ/VFS_WRITE request at the destination FS server. */	436	/* Make a VFS_READ/VFS_WRITE request at the destination FS server. */
441	aid_t msg;	437	aid_t msg;
442	ipc_call_t answer;	438	ipc_call_t answer;
443	if (!read && file->append)	439	if (!read && file->append)
444	file->pos = file->node->size;	440	file->pos = file->node->size;
445	msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),	441	msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
446	file->node->dev_handle, file->node->index, file->pos, &answer);	442	file->node->dev_handle, file->node->index, file->pos, &answer);
447		443
448	/*	444	/*
449	* Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the	445	* Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
450	* destination FS server. The call will be routed as if sent by	446	* destination FS server. The call will be routed as if sent by
451	* ourselves. Note that call arguments are immutable in this case so we	447	* ourselves. Note that call arguments are immutable in this case so we
452	* don't have to bother.	448	* don't have to bother.
453	*/	449	*/
454	ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);	450	ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
455		451
456	vfs_release_phone(fs_phone);	452	vfs_release_phone(fs_phone);
457		453
458	/* Wait for reply from the FS server. */	454	/* Wait for reply from the FS server. */
459	ipcarg_t rc;	455	ipcarg_t rc;
460	async_wait_for(msg, &rc);	456	async_wait_for(msg, &rc);
461	size_t bytes = IPC_GET_ARG1(answer);	457	size_t bytes = IPC_GET_ARG1(answer);
462		458
463	/* Unlock the VFS node. */	459	/* Unlock the VFS node. */
464	if (read)	460	if (read)
465	rwlock_read_unlock(&file->node->contents_rwlock);	461	rwlock_read_unlock(&file->node->contents_rwlock);
466	else {	462	else {
467	/* Update the cached version of node's size. */	463	/* Update the cached version of node's size. */
468	if (rc == EOK)	464	if (rc == EOK)
469	file->node->size = IPC_GET_ARG2(answer);	465	file->node->size = IPC_GET_ARG2(answer);
470	rwlock_write_unlock(&file->node->contents_rwlock);	466	rwlock_write_unlock(&file->node->contents_rwlock);
471	}	467	}
472		468
473	/* Update the position pointer and unlock the open file. */	469	/* Update the position pointer and unlock the open file. */
474	if (rc == EOK)	470	if (rc == EOK)
475	file->pos += bytes;	471	file->pos += bytes;
476	futex_up(&file->lock);	472	futex_up(&file->lock);
477		473
478	/*	474	/*
479	* FS server's reply is the final result of the whole operation we	475	* FS server's reply is the final result of the whole operation we
480	* return to the client.	476	* return to the client.
481	*/	477	*/
482	ipc_answer_1(rid, rc, bytes);	478	ipc_answer_1(rid, rc, bytes);
483	}	479	}
484		480
485	void vfs_read(ipc_callid_t rid, ipc_call_t *request)	481	void vfs_read(ipc_callid_t rid, ipc_call_t *request)
486	{	482	{
487	vfs_rdwr(rid, request, true);	483	vfs_rdwr(rid, request, true);
488	}	484	}
489		485
490	void vfs_write(ipc_callid_t rid, ipc_call_t *request)	486	void vfs_write(ipc_callid_t rid, ipc_call_t *request)
491	{	487	{
492	vfs_rdwr(rid, request, false);	488	vfs_rdwr(rid, request, false);
493	}	489	}
494		490
495	void vfs_seek(ipc_callid_t rid, ipc_call_t *request)	491	void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
496	{	492	{
497	int fd = (int) IPC_GET_ARG1(*request);	493	int fd = (int) IPC_GET_ARG1(*request);
498	off_t off = (off_t) IPC_GET_ARG2(*request);	494	off_t off = (off_t) IPC_GET_ARG2(*request);
499	int whence = (int) IPC_GET_ARG3(*request);	495	int whence = (int) IPC_GET_ARG3(*request);
500		496

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(root)/branches/dynload/uspace/srv/vfs/vfs_ops.c – Rev 3153 → 3219