source: mainline/uspace/lib/c/generic/vfs/vfs.c@ ef4cf62

/*
 * 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 libc
 * @{
 */
/** @file
 */

#include <vfs/canonify.h>
#include <vfs/vfs.h>
#include <vfs/vfs_sess.h>
#include <macros.h>
#include <stdlib.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/types.h>
#include <ipc/services.h>
#include <ns.h>
#include <async.h>
#include <fibril_synch.h>
#include <errno.h>
#include <assert.h>
#include <str.h>
#include <loc.h>
#include <ipc/vfs.h>
#include <ipc/loc.h>

static FIBRIL_MUTEX_INITIALIZE(vfs_mutex);
static async_sess_t *vfs_sess = NULL;

static FIBRIL_MUTEX_INITIALIZE(cwd_mutex);

static int cwd_fd = -1;
static char *cwd_path = NULL;
static size_t cwd_size = 0;

static FIBRIL_MUTEX_INITIALIZE(root_mutex);
static int root_fd = -1;

int vfs_root(void)
{
        fibril_mutex_lock(&root_mutex); 
        int r;
        if (root_fd < 0) {
                r = ENOENT;
        } else {
                r = vfs_clone(root_fd, true);
        }
        fibril_mutex_unlock(&root_mutex);
        return r;
}

void vfs_root_set(int nroot)
{
        fibril_mutex_lock(&root_mutex);
        if (root_fd >= 0) {
                close(root_fd);
        }
        root_fd = vfs_clone(nroot, true);
        fibril_mutex_unlock(&root_mutex);
}

/** Start an async exchange on the VFS session.
 *
 * @return New exchange.
 *
 */
async_exch_t *vfs_exchange_begin(void)
{
        fibril_mutex_lock(&vfs_mutex);
        
        while (vfs_sess == NULL)
                vfs_sess = service_connect_blocking(SERVICE_VFS, INTERFACE_VFS,
                    0);
        
        fibril_mutex_unlock(&vfs_mutex);
        
        return async_exchange_begin(vfs_sess);
}

/** Finish an async exchange on the VFS session.
 *
 * @param exch Exchange to be finished.
 *
 */
void vfs_exchange_end(async_exch_t *exch)
{
        async_exchange_end(exch);
}

int _vfs_walk(int parent, const char *path, int flags)
{
        async_exch_t *exch = vfs_exchange_begin();
        
        ipc_call_t answer;
        aid_t req = async_send_2(exch, VFS_IN_WALK, parent, flags, &answer);
        sysarg_t rc = async_data_write_start(exch, path, str_size(path));
        vfs_exchange_end(exch);
                
        sysarg_t rc_orig;
        async_wait_for(req, &rc_orig);

        if (rc_orig != EOK) {
                return (int) rc_orig;
        }
                
        if (rc != EOK) {
                return (int) rc;
        }
        
        return (int) IPC_GET_ARG1(answer);
}

int vfs_lookup(const char *path, int flags)
{
        size_t size;
        char *p = vfs_absolutize(path, &size);
        if (!p) {
                return ENOMEM;
        }
        int root = vfs_root();
        if (root == -1) {
                free(p);
                return ENOENT;
        }
        int rc = _vfs_walk(root, p, flags);
        close(root);
        free(p);
        return rc;
}

int _vfs_open(int fildes, int mode)
{
        async_exch_t *exch = vfs_exchange_begin();
        sysarg_t rc = async_req_2_0(exch, VFS_IN_OPEN2, fildes, mode);
        vfs_exchange_end(exch);
        
        return (int) rc;
}

char *vfs_absolutize(const char *path, size_t *retlen)
{
        char *ncwd_path;
        char *ncwd_path_nc;

        fibril_mutex_lock(&cwd_mutex);
        size_t size = str_size(path);
        if (*path != '/') {
                if (cwd_path == NULL) {
                        fibril_mutex_unlock(&cwd_mutex);
                        return NULL;
                }
                ncwd_path_nc = malloc(cwd_size + 1 + size + 1);
                if (ncwd_path_nc == NULL) {
                        fibril_mutex_unlock(&cwd_mutex);
                        return NULL;
                }
                str_cpy(ncwd_path_nc, cwd_size + 1 + size + 1, cwd_path);
                ncwd_path_nc[cwd_size] = '/';
                ncwd_path_nc[cwd_size + 1] = '\0';
        } else {
                ncwd_path_nc = malloc(size + 1);
                if (ncwd_path_nc == NULL) {
                        fibril_mutex_unlock(&cwd_mutex);
                        return NULL;
                }
                ncwd_path_nc[0] = '\0';
        }
        str_append(ncwd_path_nc, cwd_size + 1 + size + 1, path);
        ncwd_path = canonify(ncwd_path_nc, retlen);
        if (ncwd_path == NULL) {
                fibril_mutex_unlock(&cwd_mutex);
                free(ncwd_path_nc);
                return NULL;
        }
        /*
         * We need to clone ncwd_path because canonify() works in-place and thus
         * the address in ncwd_path need not be the same as ncwd_path_nc, even
         * though they both point into the same dynamically allocated buffer.
         */
        ncwd_path = str_dup(ncwd_path);
        free(ncwd_path_nc);
        if (ncwd_path == NULL) {
                fibril_mutex_unlock(&cwd_mutex);
                return NULL;
        }
        fibril_mutex_unlock(&cwd_mutex);
        return ncwd_path;
}

int vfs_mount(int mp, const char *fs_name, service_id_t serv, const char *opts,
unsigned int flags, unsigned int instance, int *mountedfd)
{
        sysarg_t rc, rc1;
        
        if (!mountedfd) {
                flags |= VFS_MOUNT_NO_REF;
        }
        if (mp < 0) {
                flags |= VFS_MOUNT_CONNECT_ONLY;
        }
        
        ipc_call_t answer;
        async_exch_t *exch = vfs_exchange_begin();
        aid_t req = async_send_4(exch, VFS_IN_MOUNT, mp, serv, flags, instance, &answer);

        rc1 = async_data_write_start(exch, (void *) opts, str_size(opts));
        
        if (rc1 == EOK) {
                rc1 = async_data_write_start(exch, (void *) fs_name, str_size(fs_name));
        }

        vfs_exchange_end(exch);

        async_wait_for(req, &rc);

        if (mountedfd) {
                *mountedfd = (int) IPC_GET_ARG1(answer);
        }
        
        if (rc != EOK) {
                return rc;
        }
        return rc1;
}

int vfs_unmount(int mp)
{
        async_exch_t *exch = vfs_exchange_begin();
        int rc = async_req_1_0(exch, VFS_IN_UNMOUNT, mp);
        vfs_exchange_end(exch);
        return rc;
}

int mount(const char *fs_name, const char *mp, const char *fqsn,
    const char *opts, unsigned int flags, unsigned int instance)
{
        int null_id = -1;
        char null[LOC_NAME_MAXLEN];
        
        if (str_cmp(fqsn, "") == 0) {
                /* No device specified, create a fresh
                   null/%d device instead */
                null_id = loc_null_create();
                
                if (null_id == -1)
                        return ENOMEM;
                
                snprintf(null, LOC_NAME_MAXLEN, "null/%d", null_id);
                fqsn = null;
        }
        
        if (flags & IPC_FLAG_BLOCKING) {
                flags = VFS_MOUNT_BLOCKING;
        } else {
                flags = 0;
        }
        
        service_id_t service_id;
        int res = loc_service_get_id(fqsn, &service_id, flags);
        if (res != EOK) {
                if (null_id != -1)
                        loc_null_destroy(null_id);
                
                return res;
        }
        
        size_t mpa_size;
        char *mpa = vfs_absolutize(mp, &mpa_size);
        if (mpa == NULL) {
                if (null_id != -1)
                        loc_null_destroy(null_id);
                
                return ENOMEM;
        }
        
        fibril_mutex_lock(&root_mutex);
        
        int rc;
        
        if (str_cmp(mpa, "/") == 0) {
                /* Mounting root. */
                
                if (root_fd >= 0) {
                        fibril_mutex_unlock(&root_mutex);
                        if (null_id != -1) {
                                loc_null_destroy(null_id);
                        }
                        return EBUSY;
                }
                
                int root;
                rc = vfs_mount(-1, fs_name, service_id, opts, flags, instance, &root);
                if (rc == EOK) {
                        root_fd = root;
                }
        } else {
                if (root_fd < 0) {
                        fibril_mutex_unlock(&root_mutex);
                        if (null_id != -1) {
                                loc_null_destroy(null_id);
                        }
                        return EINVAL;
                }
                
                int mpfd = _vfs_walk(root_fd, mpa, WALK_DIRECTORY);
                if (mpfd >= 0) {
                        rc = vfs_mount(mpfd, fs_name, service_id, opts, flags, instance, NULL);
                        close(mpfd);
                } else {
                        rc = mpfd;
                }
        }
        
        fibril_mutex_unlock(&root_mutex);
        
        if ((rc != EOK) && (null_id != -1))
                loc_null_destroy(null_id);
        
        return (int) rc;
}

int unmount(const char *mpp)
{
        int mp = vfs_lookup(mpp, WALK_MOUNT_POINT | WALK_DIRECTORY);
        if (mp < 0) {
                return mp;
        }
        
        int rc = vfs_unmount(mp);
        close(mp);
        return rc;
}

static int walk_flags(int oflags)
{
        int flags = 0;
        if (oflags & O_CREAT) {
                if (oflags & O_EXCL) {
                        flags |= WALK_MUST_CREATE;
                } else {
                        flags |= WALK_MAY_CREATE;
                }
        }
        return flags;
}

/** Open file.
 *
 * @param path File path
 * @param oflag O_xxx flags
 * @param mode File mode (only with O_CREAT)
 *
 * @return Nonnegative file descriptor on success. On error -1 is returned
 *         and errno is set.
 */
int open(const char *path, int oflag, ...)
{
        // FIXME: Some applications call this incorrectly.
        if ((oflag & (O_RDONLY|O_WRONLY|O_RDWR)) == 0) {
                oflag |= O_RDWR;
        }

        assert((((oflag & O_RDONLY) != 0) + ((oflag & O_WRONLY) != 0) + ((oflag & O_RDWR) != 0)) == 1);
        
        int ret = vfs_lookup(path, walk_flags(oflag) | WALK_REGULAR);
        if (ret < 0) {
                return ret;
        }
        
        int mode =
                ((oflag & O_RDWR) ? MODE_READ|MODE_WRITE : 0) |
                ((oflag & O_RDONLY) ? MODE_READ : 0) |
                ((oflag & O_WRONLY) ? MODE_WRITE : 0) |
                ((oflag & O_APPEND) ? MODE_APPEND : 0);
        
        int rc = _vfs_open(ret, mode); 
        if (rc < 0) {
                // _vfs_put(ret);
                close(ret);
                return rc;
        }
        
        if (oflag & O_TRUNC) {
                assert(oflag & O_WRONLY || oflag & O_RDWR);
                assert(!(oflag & O_APPEND));
                
                // _vfs_resize
                (void) ftruncate(ret, 0);
        }

        return ret;
}

/** Close file.
 *
 * @param fildes File descriptor
 * @return Zero on success. On error -1 is returned and errno is set.
 */
int close(int fildes)
{
        sysarg_t rc;
        
        async_exch_t *exch = vfs_exchange_begin();
        rc = async_req_1_0(exch, VFS_IN_CLOSE, fildes);
        vfs_exchange_end(exch);
        
        if (rc != EOK) {
                errno = rc;
                return -1;
        }
        
        return 0;
}

/** Read bytes from file.
 *
 * Read up to @a nbyte bytes from file. The actual number of bytes read
 * may be lower, but greater than zero if there are any bytes available.
 * If there are no bytes available for reading, then the function will
 * return success with zero bytes read.
 *
 * @param fildes File descriptor
 * @param buf Buffer
 * @param nbyte Maximum number of bytes to read
 * @param nread Place to store actual number of bytes read (0 or more)
 *
 * @return EOK on success, non-zero error code on error.
 */
static int _read_short(int fildes, void *buf, size_t nbyte, ssize_t *nread)
{
        sysarg_t rc;
        ipc_call_t answer;
        aid_t req;
        
        if (nbyte > DATA_XFER_LIMIT)
                nbyte = DATA_XFER_LIMIT;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_1(exch, VFS_IN_READ, fildes, &answer);
        rc = async_data_read_start(exch, (void *) buf, nbyte);

        vfs_exchange_end(exch);
        
        if (rc == EOK) {
                async_wait_for(req, &rc);
        } else {
                async_forget(req);
        }
        
        if (rc != EOK)
                return rc;
        
        *nread = (ssize_t) IPC_GET_ARG1(answer);
        return EOK;
}

/** Write bytes to file.
 *
 * Write up to @a nbyte bytes from file. The actual number of bytes written
 * may be lower, but greater than zero.
 *
 * @param fildes File descriptor
 * @param buf Buffer
 * @param nbyte Maximum number of bytes to write
 * @param nread Place to store actual number of bytes written (0 or more)
 *
 * @return EOK on success, non-zero error code on error.
 */
static int _write_short(int fildes, const void *buf, size_t nbyte,
    ssize_t *nwritten)
{
        sysarg_t rc;
        ipc_call_t answer;
        aid_t req;
        
        if (nbyte > DATA_XFER_LIMIT)
                nbyte = DATA_XFER_LIMIT;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_1(exch, VFS_IN_WRITE, fildes, &answer);
        rc = async_data_write_start(exch, (void *) buf, nbyte);
        
        vfs_exchange_end(exch);
        
        if (rc == EOK) {
                async_wait_for(req, &rc);
        } else {
                async_forget(req);
        }

        if (rc != EOK)
                return rc;
        
        *nwritten = (ssize_t) IPC_GET_ARG1(answer);
        return EOK;
}

/** Read data.
 *
 * Read up to @a nbytes bytes from file if available. This function always reads
 * all the available bytes up to @a nbytes.
 *
 * @param fildes        File descriptor
 * @param buf           Buffer, @a nbytes bytes long
 * @param nbytes        Number of bytes to read
 *
 * @return              On success, nonnegative number of bytes read.
 *                      On failure, -1 and sets errno.
 */
ssize_t read(int fildes, void *buf, size_t nbyte)
{
        ssize_t cnt = 0;
        size_t nread = 0;
        uint8_t *bp = (uint8_t *) buf;
        int rc;
        
        do {
                bp += cnt;
                nread += cnt;
                rc = _read_short(fildes, bp, nbyte - nread, &cnt);
        } while (rc == EOK && cnt > 0 && (nbyte - nread - cnt) > 0);
        
        if (rc != EOK) {
                errno = rc;
                return -1;
        }
        
        return nread + cnt;
}

/** Write data.
 *
 * This function fails if it cannot write exactly @a len bytes to the file.
 *
 * @param fildes        File descriptor
 * @param buf           Data, @a nbytes bytes long
 * @param nbytes        Number of bytes to write
 *
 * @return              On success, nonnegative number of bytes written.
 *                      On failure, -1 and sets errno.
 */
ssize_t write(int fildes, const void *buf, size_t nbyte)
{
        ssize_t cnt = 0;
        ssize_t nwritten = 0;
        const uint8_t *bp = (uint8_t *) buf;
        int rc;

        do {
                bp += cnt;
                nwritten += cnt;
                rc = _write_short(fildes, bp, nbyte - nwritten, &cnt);
        } while (rc == EOK && ((ssize_t )nbyte - nwritten - cnt) > 0);

        if (rc != EOK) {
                errno = rc;
                return -1;
        }

        return nbyte;
}

/** Synchronize file.
 *
 * @param fildes File descriptor
 * @return 0 on success. On error returns -1 and sets errno.
 */
int fsync(int fildes)
{
        async_exch_t *exch = vfs_exchange_begin();
        sysarg_t rc = async_req_1_0(exch, VFS_IN_SYNC, fildes);
        vfs_exchange_end(exch);
        
        if (rc != EOK) {
                errno = rc;
                return -1;
        }
        
        return 0;
}

/** Seek to a position.
 *
 * @param fildes File descriptor
 * @param offset Offset
 * @param whence SEEK_SET, SEEK_CUR or SEEK_END
 *
 * @return On success the nonnegative offset from start of file. On error
 *         returns (off64_t)-1 and sets errno.
 */
off64_t lseek(int fildes, off64_t offset, int whence)
{
        async_exch_t *exch = vfs_exchange_begin();
        
        sysarg_t newoff_lo;
        sysarg_t newoff_hi;
        sysarg_t rc = async_req_4_2(exch, VFS_IN_SEEK, fildes,
            LOWER32(offset), UPPER32(offset), whence,
            &newoff_lo, &newoff_hi);
        
        vfs_exchange_end(exch);
        
        if (rc != EOK) {
                errno = rc;
                return (off64_t) -1;
        }
        
        return (off64_t) MERGE_LOUP32(newoff_lo, newoff_hi);
}

/** Truncate file to a specified length.
 *
 * Truncate file so that its size is exactly @a length
 *
 * @param fildes File descriptor
 * @param length Length
 *
 * @return 0 on success, -1 on error and sets errno.
 */
int ftruncate(int fildes, aoff64_t length)
{
        sysarg_t rc;
        
        async_exch_t *exch = vfs_exchange_begin();
        rc = async_req_3_0(exch, VFS_IN_TRUNCATE, fildes,
            LOWER32(length), UPPER32(length));
        vfs_exchange_end(exch);
        
        if (rc != EOK) {
                errno = rc;
                return -1;
        }
        
        return 0;
}

/** Get file status.
 *
 * @param fildes File descriptor
 * @param stat Place to store file information
 *
 * @return 0 on success, -1 on error and sets errno.
 */
int fstat(int fildes, struct stat *stat)
{
        sysarg_t rc;
        aid_t req;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_1(exch, VFS_IN_FSTAT, fildes, NULL);
        rc = async_data_read_start(exch, (void *) stat, sizeof(struct stat));
        if (rc != EOK) {
                vfs_exchange_end(exch);
                
                sysarg_t rc_orig;
                async_wait_for(req, &rc_orig);
                
                if (rc_orig != EOK)
                        rc = rc_orig;
                if (rc != EOK) {
                        errno = rc;
                        return -1;
                }
                
                return 0;
        }
        
        vfs_exchange_end(exch);
        async_wait_for(req, &rc);
        
        if (rc != EOK) {
                errno = rc;
                return -1;
        }
        
        return 0;
}

/** Get file status.
 *
 * @param path Path to file
 * @param stat Place to store file information
 *
 * @return 0 on success, -1 on error and sets errno.
 */
int stat(const char *path, struct stat *stat)
{
        int fd = vfs_lookup(path, 0);
        if (fd < 0) {
                return fd;
        }
        
        int rc = fstat(fd, stat);
        close(fd);
        return rc;
}

/** Open directory.
 *
 * @param dirname Directory pathname
 *
 * @return Non-NULL pointer on success. On error returns @c NULL and sets errno.
 */
DIR *opendir(const char *dirname)
{
        DIR *dirp = malloc(sizeof(DIR));
        if (!dirp) {
                errno = ENOMEM;
                return NULL;
        }
        
        int ret = vfs_lookup(dirname, WALK_DIRECTORY);
        if (ret < 0) {
                free(dirp);
                errno = ret;
                return NULL;
        }
        
        int rc = _vfs_open(ret, MODE_READ);
        if (rc < 0) {
                free(dirp);
                close(ret);
                errno = rc;
                return NULL;
        }
        
        dirp->fd = ret;
        return dirp;
}

/** Read directory entry.
 *
 * @param dirp Open directory
 * @return Non-NULL pointer to directory entry on success. On error returns
 *         @c NULL and sets errno.
 */
struct dirent *readdir(DIR *dirp)
{
        int rc;
        ssize_t len;
        
        rc = _read_short(dirp->fd, &dirp->res.d_name[0], NAME_MAX + 1, &len);
        if (rc != EOK) {
                errno = rc;
                return NULL;
        }
        
        (void) len;
        return &dirp->res;
}

/** Rewind directory position to the beginning.
 *
 * @param dirp Open directory
 */
void rewinddir(DIR *dirp)
{
        (void) lseek(dirp->fd, 0, SEEK_SET);
}

/** Close directory.
 *
 * @param dirp Open directory
 * @return 0 on success. On error returns -1 and sets errno.
 */
int closedir(DIR *dirp)
{
        int rc;
        
        rc = close(dirp->fd);
        free(dirp);

        /* On error errno was set by close() */
        return rc;
}

/** Create directory.
 *
 * @param path Path
 * @param mode File mode
 * @return 0 on success. On error returns -1 and sets errno.
 */
int mkdir(const char *path, mode_t mode)
{
        int ret = vfs_lookup(path, WALK_MUST_CREATE | WALK_DIRECTORY);
        if (ret < 0) {
                return ret;
        }
        
        close(ret);
        return EOK;
}

static int _vfs_unlink2(int parent, const char *path, int expect, int wflag)
{
        sysarg_t rc;
        aid_t req;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_3(exch, VFS_IN_UNLINK2, parent, expect, wflag, NULL);
        rc = async_data_write_start(exch, path, str_size(path));
        
        vfs_exchange_end(exch);
        
        sysarg_t rc_orig;
        async_wait_for(req, &rc_orig);
        
        if (rc_orig != EOK) {
                return (int) rc_orig;
        }
        return rc;
}

/** Unlink file or directory.
 *
 * @param path Path
 * @return EOk on success, error code on error
 */
int unlink(const char *path)
{
        size_t pa_size;
        char *pa = vfs_absolutize(path, &pa_size);
        if (!pa) {
                return ENOMEM;
        }
        
        int root = vfs_root();
        if (root < 0) {
                free(pa);
                return ENOENT;
        }
        
        int rc = _vfs_unlink2(root, pa, -1, 0);
        
        free(pa);
        close(root);
        return rc;
}

/** Remove empty directory.
 *
 * @param path Path
 * @return 0 on success. On error returns -1 and sets errno.
 */
int rmdir(const char *path)
{
        size_t pa_size;
        char *pa = vfs_absolutize(path, &pa_size);
        if (!pa) {
                return ENOMEM;
        }
        
        int root = vfs_root();
        if (root < 0) {
                free(pa);
                return ENOENT;
        }
        
        int rc = _vfs_unlink2(root, pa, -1, WALK_DIRECTORY);
        
        free(pa);
        close(root);
        return rc;
}

/** Rename directory entry.
 *
 * @param old Old name
 * @param new New name
 *
 * @return 0 on success. On error returns -1 and sets errno.
 */
int rename(const char *old, const char *new)
{
        sysarg_t rc;
        sysarg_t rc_orig;
        aid_t req;
        
        size_t olda_size;
        char *olda = vfs_absolutize(old, &olda_size);
        if (olda == NULL) {
                errno = ENOMEM;
                return -1;
        }

        size_t newa_size;
        char *newa = vfs_absolutize(new, &newa_size);
        if (newa == NULL) {
                free(olda);
                errno = ENOMEM;
                return -1;
        }
        
        async_exch_t *exch = vfs_exchange_begin();
        int root = vfs_root();
        if (root < 0) {
                free(olda);
                free(newa);
                return ENOENT;
        }
        
        req = async_send_1(exch, VFS_IN_RENAME, root, NULL);
        rc = async_data_write_start(exch, olda, olda_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(olda);
                free(newa);
                close(root);
                async_wait_for(req, &rc_orig);
                if (rc_orig != EOK)
                        rc = rc_orig;
                if (rc != EOK) {
                        errno = rc;
                        return -1;
                }
                return 0;
        }
        rc = async_data_write_start(exch, newa, newa_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(olda);
                free(newa);
                close(root);
                async_wait_for(req, &rc_orig);
                if (rc_orig != EOK)
                        rc = rc_orig;
                if (rc != EOK) {
                        errno = rc;
                        return -1;
                }
                return 0;
        }
        vfs_exchange_end(exch);
        free(olda);
        free(newa);
        close(root);
        async_wait_for(req, &rc);

        if (rc != EOK) {
                errno = rc;
                return -1;
        }

        return 0;
}

/** Remove directory entry.
 *
 * @param path Path
 * @return 0 on success. On error returns -1 and sets errno.
 */
int remove(const char *path)
{
        return unlink(path);
}

/** Change working directory.
 *
 * @param path Path
 * @return 0 on success. On error returns -1 and sets errno.
 */
int chdir(const char *path)
{
        size_t abs_size;
        char *abs = vfs_absolutize(path, &abs_size);
        if (!abs)
                return ENOMEM;
        
        int fd = vfs_lookup(abs, WALK_DIRECTORY);
        if (fd < 0) {
                free(abs);
                errno = fd;
                return -1;
        }
        
        fibril_mutex_lock(&cwd_mutex);
        
        if (cwd_fd >= 0) {
                close(cwd_fd);
        }
        
        if (cwd_path) {
                free(cwd_path);
        }
        
        cwd_fd = fd;
        cwd_path = abs;
        cwd_size = abs_size;
        
        fibril_mutex_unlock(&cwd_mutex);
        return 0;
}

/** Get current working directory path.
 *
 * @param buf Buffer
 * @param size Size of @a buf
 * @return On success returns @a buf. On failure returns @c NULL and sets errno.
 */
char *getcwd(char *buf, size_t size)
{
        if (size == 0) {
                errno = EINVAL;
                return NULL;
        }
        
        fibril_mutex_lock(&cwd_mutex);
        
        if ((cwd_size == 0) || (size < cwd_size + 1)) {
                fibril_mutex_unlock(&cwd_mutex);
                errno = ERANGE;
                return NULL;
        }
        
        str_cpy(buf, size, cwd_path);
        fibril_mutex_unlock(&cwd_mutex);
        
        return buf;
}

/** Open session to service represented by a special file.
 *
 * Given that the file referred to by @a fildes represents a service,
 * open a session to that service.
 *
 * @param fildes File descriptor
 * @param iface Interface to connect to (XXX Should be automatic)
 * @return On success returns session pointer. On error returns @c NULL.
 */
async_sess_t *vfs_fd_session(int fildes, iface_t iface)
{
        struct stat stat;
        int rc = fstat(fildes, &stat);
        if (rc != 0)
                return NULL;
        
        if (stat.service == 0)
                return NULL;
        
        return loc_service_connect(stat.service, iface, 0);
}

/** Duplicate open file.
 *
 * Duplicate open file under a new file descriptor.
 *
 * @param oldfd Old file descriptor
 * @param newfd New file descriptor
 * @return 0 on success. On error -1 is returned and errno is set
 */
int dup2(int oldfd, int newfd)
{
        async_exch_t *exch = vfs_exchange_begin();
        
        sysarg_t ret;
        sysarg_t rc = async_req_2_1(exch, VFS_IN_DUP, oldfd, newfd, &ret);
        
        vfs_exchange_end(exch);
        
        if (rc == EOK)
                rc = ret;
        
        if (rc != EOK) {
                errno = rc;
                return -1;
        }
        
        return 0;
}

int vfs_get_mtab_list(list_t *mtab_list)
{
        sysarg_t rc;
        aid_t req;
        size_t i;
        sysarg_t num_mounted_fs;
        
        async_exch_t *exch = vfs_exchange_begin();

        req = async_send_0(exch, VFS_IN_MTAB_GET, NULL);

        /* Ask VFS how many filesystems are mounted */
        rc = async_req_0_1(exch, VFS_IN_PING, &num_mounted_fs);
        if (rc != EOK)
                goto exit;

        for (i = 0; i < num_mounted_fs; ++i) {
                mtab_ent_t *mtab_ent;

                mtab_ent = malloc(sizeof(mtab_ent_t));
                if (mtab_ent == NULL) {
                        rc = ENOMEM;
                        goto exit;
                }

                memset(mtab_ent, 0, sizeof(mtab_ent_t));

                rc = async_data_read_start(exch, (void *) mtab_ent->mp,
                    MAX_PATH_LEN);
                if (rc != EOK)
                        goto exit;

                rc = async_data_read_start(exch, (void *) mtab_ent->opts,
                        MAX_MNTOPTS_LEN);
                if (rc != EOK)
                        goto exit;

                rc = async_data_read_start(exch, (void *) mtab_ent->fs_name,
                        FS_NAME_MAXLEN);
                if (rc != EOK)
                        goto exit;

                sysarg_t p[2];

                rc = async_req_0_2(exch, VFS_IN_PING, &p[0], &p[1]);
                if (rc != EOK)
                        goto exit;

                mtab_ent->instance = p[0];
                mtab_ent->service_id = p[1];

                link_initialize(&mtab_ent->link);
                list_append(&mtab_ent->link, mtab_list);
        }

exit:
        async_wait_for(req, &rc);
        vfs_exchange_end(exch);
        return rc;
}

/** Get filesystem statistics.
 *
 * @param path Mount point path
 * @param st Buffer for storing information
 * @return 0 on success. On error -1 is returned and errno is set.
 */
int statfs(const char *path, struct statfs *st)
{
        int fd = vfs_lookup(path, 0);
        if (fd < 0) {
                errno = fd;
                return -1;
        }
        
        sysarg_t rc, ret;
        aid_t req;

        async_exch_t *exch = vfs_exchange_begin();

        req = async_send_1(exch, VFS_IN_STATFS, fd, NULL);
        rc = async_data_read_start(exch, (void *) st, sizeof(*st));

        vfs_exchange_end(exch);
        async_wait_for(req, &ret);
        close(fd);

        rc = (ret != EOK ? ret : rc);
        if (rc != EOK) {
                errno = rc;
                return -1;
        }

        return 0;
}

int vfs_pass_handle(async_exch_t *vfs_exch, int file, async_exch_t *exch)
{
        return async_state_change_start(exch, VFS_PASS_HANDLE, (sysarg_t)file, 0, vfs_exch);
}

int vfs_receive_handle(bool high_descriptor)
{
        ipc_callid_t callid;
        if (!async_state_change_receive(&callid, NULL, NULL, NULL)) {
                async_answer_0(callid, EINVAL);
                return EINVAL;
        }

        async_exch_t *vfs_exch = vfs_exchange_begin();

        async_state_change_finalize(callid, vfs_exch);

        sysarg_t ret;
        sysarg_t rc = async_req_1_1(vfs_exch, VFS_IN_WAIT_HANDLE, high_descriptor, &ret);

        async_exchange_end(vfs_exch);

        if (rc != EOK) {
                return rc;
        }
        return ret;
}

int vfs_clone(int file, bool high_descriptor)
{
        async_exch_t *vfs_exch = vfs_exchange_begin();
        int rc = async_req_2_0(vfs_exch, VFS_IN_CLONE, (sysarg_t) file, (sysarg_t) high_descriptor);
        vfs_exchange_end(vfs_exch);
        return rc;
}

/** @}
 */