source: mainline/uspace/lib/c/generic/vfs/vfs.c@ 089385e8

/*
 * 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/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;

/* Current (working) directory. */
static FIBRIL_MUTEX_INITIALIZE(cwd_mutex);
static int cwd_fd = -1;
static char *cwd_path = NULL;
static size_t cwd_size = 0;

/* Previous directory. */
static FIBRIL_MUTEX_INITIALIZE(pwd_mutex);
static int pwd_fd = -1;
static char *pwd_path = NULL;
static size_t pwd_size = 0;


/** 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(EXCHANGE_PARALLEL, SERVICE_VFS,
                    0, 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);
}

char *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) {
                        fibril_mutex_unlock(&cwd_mutex);
                        return NULL;
                }
                ncwd_path_nc = malloc(cwd_size + 1 + size + 1);
                if (!ncwd_path_nc) {
                        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) {
                        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) {
                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) {
                fibril_mutex_unlock(&cwd_mutex);
                return NULL;
        }
        fibril_mutex_unlock(&cwd_mutex);
        return ncwd_path;
}

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;
        }
        
        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 = absolutize(mp, &mpa_size);
        if (!mpa) {
                if (null_id != -1)
                        loc_null_destroy(null_id);
                
                return ENOMEM;
        }
        
        async_exch_t *exch = vfs_exchange_begin();

        sysarg_t rc_orig;
        aid_t req = async_send_3(exch, VFS_IN_MOUNT, service_id, flags,
            instance, NULL);
        sysarg_t rc = async_data_write_start(exch, (void *) mpa, mpa_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(mpa);
                async_wait_for(req, &rc_orig);
                
                if (null_id != -1)
                        loc_null_destroy(null_id);
                
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        
        rc = async_data_write_start(exch, (void *) opts, str_size(opts));
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(mpa);
                async_wait_for(req, &rc_orig);
                
                if (null_id != -1)
                        loc_null_destroy(null_id);
                
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        
        rc = async_data_write_start(exch, (void *) fs_name, str_size(fs_name));
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(mpa);
                async_wait_for(req, &rc_orig);
                
                if (null_id != -1)
                        loc_null_destroy(null_id);
                
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        
        /* Ask VFS whether it likes fs_name. */
        rc = async_req_0_0(exch, VFS_IN_PING);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(mpa);
                async_wait_for(req, &rc_orig);
                
                if (null_id != -1)
                        loc_null_destroy(null_id);
                
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        
        vfs_exchange_end(exch);
        free(mpa);
        async_wait_for(req, &rc);
        
        if ((rc != EOK) && (null_id != -1))
                loc_null_destroy(null_id);
        
        return (int) rc;
}

int unmount(const char *mp)
{
        sysarg_t rc;
        sysarg_t rc_orig;
        aid_t req;
        size_t mpa_size;
        char *mpa;
        
        mpa = absolutize(mp, &mpa_size);
        if (!mpa)
                return ENOMEM;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_0(exch, VFS_IN_UNMOUNT, NULL);
        rc = async_data_write_start(exch, (void *) mpa, mpa_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(mpa);
                async_wait_for(req, &rc_orig);
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        

        vfs_exchange_end(exch);
        free(mpa);
        async_wait_for(req, &rc);
        
        return (int) rc;
}

static int open_internal(const char *abs, size_t abs_size, int lflag, int oflag)
{
        async_exch_t *exch = vfs_exchange_begin();
        
        ipc_call_t answer;
        aid_t req = async_send_3(exch, VFS_IN_OPEN, lflag, oflag, 0, &answer);
        sysarg_t rc = async_data_write_start(exch, abs, abs_size);
        
        if (rc != EOK) {
                vfs_exchange_end(exch);

                sysarg_t rc_orig;
                async_wait_for(req, &rc_orig);
                
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        
        vfs_exchange_end(exch);
        async_wait_for(req, &rc);
        
        if (rc != EOK)
            return (int) rc;
        
        return (int) IPC_GET_ARG1(answer);
}

int open(const char *path, int oflag, ...)
{
        size_t abs_size;
        char *abs = absolutize(path, &abs_size);
        if (!abs)
                return ENOMEM;
        
        int ret = open_internal(abs, abs_size, L_FILE, oflag);
        free(abs);
        
        return ret;
}

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);
        
        return (int) rc;
}

ssize_t read(int fildes, void *buf, size_t nbyte) 
{
        sysarg_t rc;
        ipc_call_t answer;
        aid_t req;
        
        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);
        if (rc != EOK) {
                vfs_exchange_end(exch);

                sysarg_t rc_orig;
                async_wait_for(req, &rc_orig);

                if (rc_orig == EOK)
                        return (ssize_t) rc;
                else
                        return (ssize_t) rc_orig;
        }
        vfs_exchange_end(exch);
        async_wait_for(req, &rc);
        if (rc == EOK)
                return (ssize_t) IPC_GET_ARG1(answer);
        else
                return rc;
}

ssize_t write(int fildes, const void *buf, size_t nbyte) 
{
        sysarg_t rc;
        ipc_call_t answer;
        aid_t req;
        
        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);
        if (rc != EOK) {
                vfs_exchange_end(exch);

                sysarg_t rc_orig;
                async_wait_for(req, &rc_orig);

                if (rc_orig == EOK)
                        return (ssize_t) rc;
                else
                        return (ssize_t) rc_orig;
        }
        vfs_exchange_end(exch);
        async_wait_for(req, &rc);
        if (rc == EOK)
                return (ssize_t) IPC_GET_ARG1(answer);
        else
                return -1;
}

/** Read entire buffer.
 *
 * In face of short reads this function continues reading until either
 * the entire buffer is read or no more data is available (at end of file).
 *
 * @param fildes        File descriptor
 * @param buf           Buffer, @a nbytes bytes long
 * @param nbytes        Number of bytes to read
 *
 * @return              On success, positive number of bytes read.
 *                      On failure, negative error code from read().
 */
ssize_t read_all(int fildes, void *buf, size_t nbyte)
{
        ssize_t cnt = 0;
        size_t nread = 0;
        uint8_t *bp = (uint8_t *) buf;

        do {
                bp += cnt;
                nread += cnt;
                cnt = read(fildes, bp, nbyte - nread);
        } while (cnt > 0 && (nbyte - nread - cnt) > 0);

        if (cnt < 0)
                return cnt;

        return nread + cnt;
}

/** Write entire buffer.
 *
 * 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              EOK on error, return value from write() if writing
 *                      failed.
 */
ssize_t write_all(int fildes, const void *buf, size_t nbyte)
{
        ssize_t cnt = 0;
        ssize_t nwritten = 0;
        const uint8_t *bp = (uint8_t *) buf;

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

        if (cnt < 0)
                return cnt;

        if ((ssize_t)nbyte - nwritten - cnt > 0)
                return EIO;

        return nbyte;
}

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);
        
        return (int) rc;
}

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)
                return (off64_t) -1;
        
        return (off64_t) MERGE_LOUP32(newoff_lo, newoff_hi);
}

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);
        
        return (int) rc;
}

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)
                        return (ssize_t) rc;
                else
                        return (ssize_t) rc_orig;
        }
        vfs_exchange_end(exch);
        async_wait_for(req, &rc);

        return rc;
}

int stat(const char *path, struct stat *stat)
{
        sysarg_t rc;
        sysarg_t rc_orig;
        aid_t req;
        
        size_t pa_size;
        char *pa = absolutize(path, &pa_size);
        if (!pa)
                return ENOMEM;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_0(exch, VFS_IN_STAT, NULL);
        rc = async_data_write_start(exch, pa, pa_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(pa);
                async_wait_for(req, &rc_orig);
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        rc = async_data_read_start(exch, stat, sizeof(struct stat));
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(pa);
                async_wait_for(req, &rc_orig);
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        vfs_exchange_end(exch);
        free(pa);
        async_wait_for(req, &rc);
        return rc;
}

DIR *opendir(const char *dirname)
{
        DIR *dirp = malloc(sizeof(DIR));
        if (!dirp)
                return NULL;
        
        size_t abs_size;
        char *abs = absolutize(dirname, &abs_size);
        if (!abs) {
                free(dirp);
                return NULL;
        }
        
        int ret = open_internal(abs, abs_size, L_DIRECTORY, 0);
        free(abs);
        
        if (ret < 0) {
                free(dirp);
                return NULL;
        }
        
        dirp->fd = ret;
        return dirp;
}

struct dirent *readdir(DIR *dirp)
{
        ssize_t len = read(dirp->fd, &dirp->res.d_name[0], NAME_MAX + 1);
        if (len <= 0)
                return NULL;
        return &dirp->res;
}

void rewinddir(DIR *dirp)
{
        (void) lseek(dirp->fd, 0, SEEK_SET);
}

int closedir(DIR *dirp)
{
        (void) close(dirp->fd);
        free(dirp);
        return 0;
}

int mkdir(const char *path, mode_t mode)
{
        sysarg_t rc;
        aid_t req;
        
        size_t pa_size;
        char *pa = absolutize(path, &pa_size);
        if (!pa)
                return ENOMEM;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_1(exch, VFS_IN_MKDIR, mode, NULL);
        rc = async_data_write_start(exch, pa, pa_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(pa);

                sysarg_t rc_orig;
                async_wait_for(req, &rc_orig);

                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        vfs_exchange_end(exch);
        free(pa);
        async_wait_for(req, &rc);
        return rc;
}

static int _unlink(const char *path, int lflag)
{
        sysarg_t rc;
        aid_t req;
        
        size_t pa_size;
        char *pa = absolutize(path, &pa_size);
        if (!pa)
                return ENOMEM;
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_1(exch, VFS_IN_UNLINK, lflag, NULL);
        rc = async_data_write_start(exch, pa, pa_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(pa);

                sysarg_t rc_orig;
                async_wait_for(req, &rc_orig);

                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        vfs_exchange_end(exch);
        free(pa);
        async_wait_for(req, &rc);
        return rc;
}

int unlink(const char *path)
{
        return _unlink(path, L_NONE);
}

int rmdir(const char *path)
{
        return _unlink(path, L_DIRECTORY);
}

int rename(const char *old, const char *new)
{
        sysarg_t rc;
        sysarg_t rc_orig;
        aid_t req;
        
        size_t olda_size;
        char *olda = absolutize(old, &olda_size);
        if (!olda)
                return ENOMEM;

        size_t newa_size;
        char *newa = absolutize(new, &newa_size);
        if (!newa) {
                free(olda);
                return ENOMEM;
        }
        
        async_exch_t *exch = vfs_exchange_begin();
        
        req = async_send_0(exch, VFS_IN_RENAME, NULL);
        rc = async_data_write_start(exch, olda, olda_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(olda);
                free(newa);
                async_wait_for(req, &rc_orig);
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        rc = async_data_write_start(exch, newa, newa_size);
        if (rc != EOK) {
                vfs_exchange_end(exch);
                free(olda);
                free(newa);
                async_wait_for(req, &rc_orig);
                if (rc_orig == EOK)
                        return (int) rc;
                else
                        return (int) rc_orig;
        }
        vfs_exchange_end(exch);
        free(olda);
        free(newa);
        async_wait_for(req, &rc);
        return rc;
}

int chdir(const char *path)
{
        size_t abs_size;
        char *abs = absolutize(path, &abs_size);
        if (!abs)
                return ENOMEM;
        
        int fd = open_internal(abs, abs_size, L_DIRECTORY, O_DESC);
        
        if (fd < 0) {
                free(abs);
                return ENOENT;
        }
        
        fibril_mutex_lock(&cwd_mutex);
        

        fibril_mutex_lock(&pwd_mutex);

        if (pwd_fd >= 0)
                close(pwd_fd);


        if (pwd_path)
                free(pwd_path);


        pwd_fd = cwd_fd;
        pwd_path = cwd_path;
        pwd_size = cwd_size;

        fibril_mutex_unlock(&pwd_mutex);

        cwd_fd = fd;
        cwd_path = abs;
        cwd_size = abs_size;
        
        fibril_mutex_unlock(&cwd_mutex);
        return EOK;
}

char *getcwd(char *buf, size_t size)
{
        if (size == 0)
                return NULL;
        
        fibril_mutex_lock(&cwd_mutex);
        
        if ((cwd_size == 0) || (size < cwd_size + 1)) {
                fibril_mutex_unlock(&cwd_mutex);
                return NULL;
        }
        
        str_cpy(buf, size, cwd_path);
        fibril_mutex_unlock(&cwd_mutex);
        
        return buf;
}


char *getprevwd(char *buf, size_t size)
{
        if (size == 0)
                return NULL;

        fibril_mutex_lock(&pwd_mutex);

        if ((pwd_size == 0) || (size < pwd_size + 1)) {
                fibril_mutex_unlock(&pwd_mutex);
                return NULL;
        }

        str_cpy(buf, size, pwd_path);
        fibril_mutex_unlock(&pwd_mutex);

        return buf;
}

async_sess_t *fd_session(exch_mgmt_t mgmt, int fildes)
{
        struct stat stat;
        int rc = fstat(fildes, &stat);
        if (rc != 0) {
                errno = rc;
                return NULL;
        }
        
        if (!stat.service) {
                errno = ENOENT;
                return NULL;
        }
        
        return loc_service_connect(mgmt, stat.service, 0);
}

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)
                return (int) ret;
        
        return (int) rc;
}

int fd_wait(void)
{
        async_exch_t *exch = vfs_exchange_begin();
        
        sysarg_t ret;
        sysarg_t rc = async_req_0_1(exch, VFS_IN_WAIT_HANDLE, &ret);
        
        vfs_exchange_end(exch);
        
        if (rc == EOK)
                return (int) ret;
        
        return (int) rc;
}

int 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) {
                        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;
}

/** @}
 */