source: mainline/uspace/srv/fs/locfs/locfs_ops.c

/*
 * Copyright (c) 2009 Martin Decky
 * 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 locfs
 * @{
 */

/**
 * @file locfs_ops.c
 * @brief Implementation of VFS operations for the locfs file system server.
 */

#include <macros.h>
#include <stdbool.h>
#include <errno.h>
#include <stdlib.h>
#include <str.h>
#include <libfs.h>
#include <fibril_synch.h>
#include <adt/hash_table.h>
#include <ipc/loc.h>
#include <assert.h>
#include "locfs.h"
#include "locfs_ops.h"

typedef struct {
        loc_object_type_t type;
        service_id_t service_id;
} locfs_node_t;

/** Opened services structure */
typedef struct {
        service_id_t service_id;
        async_sess_t *sess;       /**< If NULL, the structure is incomplete. */
        size_t refcount;
        ht_link_t link;
        fibril_condvar_t cv;      /**< Broadcast when completed. */
} service_t;

/** Hash table of opened services */
static hash_table_t services;

/** Hash table mutex */
static FIBRIL_MUTEX_INITIALIZE(services_mutex);

/* Implementation of hash table interface for the nodes hash table. */

static size_t services_key_hash(const void *key)
{
        const service_id_t *k = key;
        return *k;
}

static size_t services_hash(const ht_link_t *item)
{
        service_t *dev = hash_table_get_inst(item, service_t, link);
        return dev->service_id;
}

static bool services_key_equal(const void *key, size_t hash,
    const ht_link_t *item)
{
        const service_id_t *k = key;
        service_t *dev = hash_table_get_inst(item, service_t, link);
        return (dev->service_id == *k);
}

static void services_remove_callback(ht_link_t *item)
{
        free(hash_table_get_inst(item, service_t, link));
}

static const hash_table_ops_t services_ops = {
        .hash = services_hash,
        .key_hash = services_key_hash,
        .key_equal = services_key_equal,
        .equal = NULL,
        .remove_callback = services_remove_callback
};

static errno_t locfs_node_get_internal(fs_node_t **rfn, loc_object_type_t type,
    service_id_t service_id)
{
        locfs_node_t *node = (locfs_node_t *) malloc(sizeof(locfs_node_t));
        if (node == NULL) {
                *rfn = NULL;
                return ENOMEM;
        }

        *rfn = (fs_node_t *) malloc(sizeof(fs_node_t));
        if (*rfn == NULL) {
                free(node);
                *rfn = NULL;
                return ENOMEM;
        }

        fs_node_initialize(*rfn);
        node->type = type;
        node->service_id = service_id;

        (*rfn)->data = node;
        return EOK;
}

static errno_t locfs_root_get(fs_node_t **rfn, service_id_t service_id)
{
        return locfs_node_get_internal(rfn, LOC_OBJECT_NONE, 0);
}

static errno_t locfs_match(fs_node_t **rfn, fs_node_t *pfn, const char *component)
{
        locfs_node_t *node = (locfs_node_t *) pfn->data;
        errno_t ret;

        if (node->service_id == 0) {
                /* Root directory */

                loc_sdesc_t *nspaces;
                size_t count = loc_get_namespaces(&nspaces);

                if (count > 0) {
                        size_t pos;
                        for (pos = 0; pos < count; pos++) {
                                /* Ignore root namespace */
                                if (str_cmp(nspaces[pos].name, "") == 0)
                                        continue;

                                if (str_cmp(nspaces[pos].name, component) == 0) {
                                        ret = locfs_node_get_internal(rfn, LOC_OBJECT_NAMESPACE, nspaces[pos].id);
                                        free(nspaces);
                                        return ret;
                                }
                        }

                        free(nspaces);
                }

                /* Search root namespace */
                service_id_t namespace;
                loc_sdesc_t *svcs;
                if (loc_namespace_get_id("", &namespace, 0) == EOK) {
                        count = loc_get_services(namespace, &svcs);

                        if (count > 0) {
                                size_t pos;
                                for (pos = 0; pos < count; pos++) {
                                        if (str_cmp(svcs[pos].name, component) == 0) {
                                                ret = locfs_node_get_internal(rfn, LOC_OBJECT_SERVICE, svcs[pos].id);
                                                free(svcs);
                                                return ret;
                                        }
                                }

                                free(svcs);
                        }
                }

                *rfn = NULL;
                return EOK;
        }

        if (node->type == LOC_OBJECT_NAMESPACE) {
                /* Namespace directory */

                loc_sdesc_t *svcs;
                size_t count = loc_get_services(node->service_id, &svcs);
                if (count > 0) {
                        size_t pos;
                        for (pos = 0; pos < count; pos++) {
                                if (str_cmp(svcs[pos].name, component) == 0) {
                                        ret = locfs_node_get_internal(rfn, LOC_OBJECT_SERVICE, svcs[pos].id);
                                        free(svcs);
                                        return ret;
                                }
                        }

                        free(svcs);
                }

                *rfn = NULL;
                return EOK;
        }

        *rfn = NULL;
        return EOK;
}

static errno_t locfs_node_get(fs_node_t **rfn, service_id_t service_id, fs_index_t index)
{
        return locfs_node_get_internal(rfn, loc_id_probe(index), index);
}

static errno_t locfs_node_open(fs_node_t *fn)
{
        locfs_node_t *node = (locfs_node_t *) fn->data;

        if (node->service_id == 0) {
                /* Root directory */
                return EOK;
        }

        loc_object_type_t type = loc_id_probe(node->service_id);

        if (type == LOC_OBJECT_NAMESPACE) {
                /* Namespace directory */
                return EOK;
        }

        if (type == LOC_OBJECT_SERVICE) {
                /* Device node */

                fibril_mutex_lock(&services_mutex);
                ht_link_t *lnk;
        restart:
                lnk = hash_table_find(&services, &node->service_id);
                if (lnk == NULL) {
                        service_t *dev = (service_t *) malloc(sizeof(service_t));
                        if (dev == NULL) {
                                fibril_mutex_unlock(&services_mutex);
                                return ENOMEM;
                        }

                        dev->service_id = node->service_id;

                        /* Mark as incomplete */
                        dev->sess = NULL;
                        dev->refcount = 1;
                        fibril_condvar_initialize(&dev->cv);

                        /*
                         * Insert the incomplete device structure so that other
                         * fibrils will not race with us when we drop the mutex
                         * below.
                         */
                        hash_table_insert(&services, &dev->link);

                        /*
                         * Drop the mutex to allow recursive locfs requests.
                         */
                        fibril_mutex_unlock(&services_mutex);

                        async_sess_t *sess = loc_service_connect(node->service_id,
                            INTERFACE_FS, 0);

                        fibril_mutex_lock(&services_mutex);

                        /*
                         * Notify possible waiters about this device structure
                         * being completed (or destroyed).
                         */
                        fibril_condvar_broadcast(&dev->cv);

                        if (!sess) {
                                /*
                                 * Connecting failed, need to remove the
                                 * entry and free the device structure.
                                 */
                                hash_table_remove(&services, &node->service_id);
                                fibril_mutex_unlock(&services_mutex);

                                return ENOENT;
                        }

                        /* Set the correct session. */
                        dev->sess = sess;
                } else {
                        service_t *dev = hash_table_get_inst(lnk, service_t, link);

                        if (!dev->sess) {
                                /*
                                 * Wait until the device structure is completed
                                 * and start from the beginning as the device
                                 * structure might have entirely disappeared
                                 * while we were not holding the mutex in
                                 * fibril_condvar_wait().
                                 */
                                fibril_condvar_wait(&dev->cv, &services_mutex);
                                goto restart;
                        }

                        dev->refcount++;
                }

                fibril_mutex_unlock(&services_mutex);

                return EOK;
        }

        return ENOENT;
}

static errno_t locfs_node_put(fs_node_t *fn)
{
        free(fn->data);
        free(fn);
        return EOK;
}

static errno_t locfs_create_node(fs_node_t **rfn, service_id_t service_id, int lflag)
{
        assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));

        *rfn = NULL;
        return ENOTSUP;
}

static errno_t locfs_destroy_node(fs_node_t *fn)
{
        return ENOTSUP;
}

static errno_t locfs_link_node(fs_node_t *pfn, fs_node_t *cfn, const char *nm)
{
        return ENOTSUP;
}

static errno_t locfs_unlink_node(fs_node_t *pfn, fs_node_t *cfn, const char *nm)
{
        return ENOTSUP;
}

static errno_t locfs_has_children(bool *has_children, fs_node_t *fn)
{
        locfs_node_t *node = (locfs_node_t *) fn->data;

        if (node->service_id == 0) {
                size_t count = loc_count_namespaces();
                if (count > 0) {
                        *has_children = true;
                        return EOK;
                }

                /* Root namespace */
                service_id_t namespace;
                if (loc_namespace_get_id("", &namespace, 0) == EOK) {
                        count = loc_count_services(namespace);
                        if (count > 0) {
                                *has_children = true;
                                return EOK;
                        }
                }

                *has_children = false;
                return EOK;
        }

        if (node->type == LOC_OBJECT_NAMESPACE) {
                size_t count = loc_count_services(node->service_id);
                if (count > 0) {
                        *has_children = true;
                        return EOK;
                }

                *has_children = false;
                return EOK;
        }

        *has_children = false;
        return EOK;
}

static fs_index_t locfs_index_get(fs_node_t *fn)
{
        locfs_node_t *node = (locfs_node_t *) fn->data;
        return node->service_id;
}

static aoff64_t locfs_size_get(fs_node_t *fn)
{
        return 0;
}

static unsigned int locfs_lnkcnt_get(fs_node_t *fn)
{
        locfs_node_t *node = (locfs_node_t *) fn->data;

        if (node->service_id == 0)
                return 0;

        return 1;
}

static bool locfs_is_directory(fs_node_t *fn)
{
        locfs_node_t *node = (locfs_node_t *) fn->data;

        return ((node->type == LOC_OBJECT_NONE) || (node->type == LOC_OBJECT_NAMESPACE));
}

static bool locfs_is_file(fs_node_t *fn)
{
        locfs_node_t *node = (locfs_node_t *) fn->data;

        return (node->type == LOC_OBJECT_SERVICE);
}

static service_id_t locfs_service_get(fs_node_t *fn)
{
        locfs_node_t *node = (locfs_node_t *) fn->data;

        if (node->type == LOC_OBJECT_SERVICE)
                return node->service_id;

        return 0;
}

/** libfs operations */
libfs_ops_t locfs_libfs_ops = {
        .root_get = locfs_root_get,
        .match = locfs_match,
        .node_get = locfs_node_get,
        .node_open = locfs_node_open,
        .node_put = locfs_node_put,
        .create = locfs_create_node,
        .destroy = locfs_destroy_node,
        .link = locfs_link_node,
        .unlink = locfs_unlink_node,
        .has_children = locfs_has_children,
        .index_get = locfs_index_get,
        .size_get = locfs_size_get,
        .lnkcnt_get = locfs_lnkcnt_get,
        .is_directory = locfs_is_directory,
        .is_file = locfs_is_file,
        .service_get = locfs_service_get
};

bool locfs_init(void)
{
        if (!hash_table_create(&services, 0,  0, &services_ops))
                return false;

        return true;
}

static errno_t locfs_fsprobe(service_id_t service_id, vfs_fs_probe_info_t *info)
{
        return ENOTSUP;
}

static errno_t locfs_mounted(service_id_t service_id, const char *opts,
    fs_index_t *index, aoff64_t *size)
{
        *index = 0;
        *size = 0;
        return EOK;
}

static errno_t locfs_unmounted(service_id_t service_id)
{
        return ENOTSUP;
}

static errno_t
locfs_read(service_id_t service_id, fs_index_t index, aoff64_t pos,
    size_t *rbytes)
{
        if (index == 0) {
                ipc_call_t call;
                size_t size;
                if (!async_data_read_receive(&call, &size)) {
                        async_answer_0(&call, EINVAL);
                        return EINVAL;
                }

                loc_sdesc_t *desc;
                size_t count = loc_get_namespaces(&desc);

                /* Get rid of root namespace */
                size_t i;
                for (i = 0; i < count; i++) {
                        if (str_cmp(desc[i].name, "") == 0) {
                                if (pos >= i)
                                        pos++;

                                break;
                        }
                }

                if (pos < count) {
                        async_data_read_finalize(&call, desc[pos].name, str_size(desc[pos].name) + 1);
                        free(desc);
                        *rbytes = 1;
                        return EOK;
                }

                free(desc);
                pos -= count;

                /* Search root namespace */
                service_id_t namespace;
                if (loc_namespace_get_id("", &namespace, 0) == EOK) {
                        count = loc_get_services(namespace, &desc);

                        if (pos < count) {
                                async_data_read_finalize(&call, desc[pos].name, str_size(desc[pos].name) + 1);
                                free(desc);
                                *rbytes = 1;
                                return EOK;
                        }

                        free(desc);
                }

                async_answer_0(&call, ENOENT);
                return ENOENT;
        }

        loc_object_type_t type = loc_id_probe(index);

        if (type == LOC_OBJECT_NAMESPACE) {
                /* Namespace directory */
                ipc_call_t call;
                size_t size;
                if (!async_data_read_receive(&call, &size)) {
                        async_answer_0(&call, EINVAL);
                        return EINVAL;
                }

                loc_sdesc_t *desc;
                size_t count = loc_get_services(index, &desc);

                if (pos < count) {
                        async_data_read_finalize(&call, desc[pos].name, str_size(desc[pos].name) + 1);
                        free(desc);
                        *rbytes = 1;
                        return EOK;
                }

                free(desc);
                async_answer_0(&call, ENOENT);
                return ENOENT;
        }

        if (type == LOC_OBJECT_SERVICE) {
                /* Device node */

                fibril_mutex_lock(&services_mutex);
                service_id_t service_index = index;
                ht_link_t *lnk = hash_table_find(&services, &service_index);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&services_mutex);
                        return ENOENT;
                }

                service_t *dev = hash_table_get_inst(lnk, service_t, link);
                assert(dev->sess);

                ipc_call_t call;
                if (!async_data_read_receive(&call, NULL)) {
                        fibril_mutex_unlock(&services_mutex);
                        async_answer_0(&call, EINVAL);
                        return EINVAL;
                }

                /* Make a request at the driver */
                async_exch_t *exch = async_exchange_begin(dev->sess);

                ipc_call_t answer;
                aid_t msg = async_send_4(exch, VFS_OUT_READ, service_id,
                    index, LOWER32(pos), UPPER32(pos), &answer);

                /* Forward the IPC_M_DATA_READ request to the driver */
                async_forward_0(&call, exch, 0, IPC_FF_ROUTE_FROM_ME);

                async_exchange_end(exch);

                fibril_mutex_unlock(&services_mutex);

                /* Wait for reply from the driver. */
                errno_t rc;
                async_wait_for(msg, &rc);

                /* Do not propagate EHANGUP back to VFS. */
                if ((errno_t) rc == EHANGUP)
                        rc = ENOTSUP;

                *rbytes = ipc_get_arg1(&answer);
                return rc;
        }

        return ENOENT;
}

static errno_t
locfs_write(service_id_t service_id, fs_index_t index, aoff64_t pos,
    size_t *wbytes, aoff64_t *nsize)
{
        if (index == 0)
                return ENOTSUP;

        loc_object_type_t type = loc_id_probe(index);

        if (type == LOC_OBJECT_NAMESPACE) {
                /* Namespace directory */
                return ENOTSUP;
        }

        if (type == LOC_OBJECT_SERVICE) {
                /* Device node */

                fibril_mutex_lock(&services_mutex);
                service_id_t service_index = index;
                ht_link_t *lnk = hash_table_find(&services, &service_index);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&services_mutex);
                        return ENOENT;
                }

                service_t *dev = hash_table_get_inst(lnk, service_t, link);
                assert(dev->sess);

                ipc_call_t call;
                if (!async_data_write_receive(&call, NULL)) {
                        fibril_mutex_unlock(&services_mutex);
                        async_answer_0(&call, EINVAL);
                        return EINVAL;
                }

                /* Make a request at the driver */
                async_exch_t *exch = async_exchange_begin(dev->sess);

                ipc_call_t answer;
                aid_t msg = async_send_4(exch, VFS_OUT_WRITE, service_id,
                    index, LOWER32(pos), UPPER32(pos), &answer);

                /* Forward the IPC_M_DATA_WRITE request to the driver */
                async_forward_0(&call, exch, 0, IPC_FF_ROUTE_FROM_ME);

                async_exchange_end(exch);

                fibril_mutex_unlock(&services_mutex);

                /* Wait for reply from the driver. */
                errno_t rc;
                async_wait_for(msg, &rc);

                /* Do not propagate EHANGUP back to VFS. */
                if ((errno_t) rc == EHANGUP)
                        rc = ENOTSUP;

                *wbytes = ipc_get_arg1(&answer);
                *nsize = 0;
                return rc;
        }

        return ENOENT;
}

static errno_t
locfs_truncate(service_id_t service_id, fs_index_t index, aoff64_t size)
{
        return ENOTSUP;
}

static errno_t locfs_close(service_id_t service_id, fs_index_t index)
{
        if (index == 0)
                return EOK;

        loc_object_type_t type = loc_id_probe(index);

        if (type == LOC_OBJECT_NAMESPACE) {
                /* Namespace directory */
                return EOK;
        }

        if (type == LOC_OBJECT_SERVICE) {

                fibril_mutex_lock(&services_mutex);
                service_id_t service_index = index;
                ht_link_t *lnk = hash_table_find(&services, &service_index);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&services_mutex);
                        return ENOENT;
                }

                service_t *dev = hash_table_get_inst(lnk, service_t, link);
                assert(dev->sess);
                dev->refcount--;

                if (dev->refcount == 0) {
                        async_hangup(dev->sess);
                        service_id_t service_index = index;
                        hash_table_remove(&services, &service_index);
                }

                fibril_mutex_unlock(&services_mutex);

                return EOK;
        }

        return ENOENT;
}

static errno_t locfs_sync(service_id_t service_id, fs_index_t index)
{
        if (index == 0)
                return EOK;

        loc_object_type_t type = loc_id_probe(index);

        if (type == LOC_OBJECT_NAMESPACE) {
                /* Namespace directory */
                return EOK;
        }

        if (type == LOC_OBJECT_SERVICE) {

                fibril_mutex_lock(&services_mutex);
                service_id_t service_index = index;
                ht_link_t *lnk = hash_table_find(&services, &service_index);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&services_mutex);
                        return ENOENT;
                }

                service_t *dev = hash_table_get_inst(lnk, service_t, link);
                assert(dev->sess);

                /* Make a request at the driver */
                async_exch_t *exch = async_exchange_begin(dev->sess);

                ipc_call_t answer;
                aid_t msg = async_send_2(exch, VFS_OUT_SYNC, service_id,
                    index, &answer);

                async_exchange_end(exch);

                fibril_mutex_unlock(&services_mutex);

                /* Wait for reply from the driver */
                errno_t rc;
                async_wait_for(msg, &rc);

                return rc;
        }

        return  ENOENT;
}

static errno_t locfs_destroy(service_id_t service_id, fs_index_t index)
{
        return ENOTSUP;
}

vfs_out_ops_t locfs_ops = {
        .fsprobe = locfs_fsprobe,
        .mounted = locfs_mounted,
        .unmounted = locfs_unmounted,
        .read = locfs_read,
        .write = locfs_write,
        .truncate = locfs_truncate,
        .close = locfs_close,
        .destroy = locfs_destroy,
        .sync = locfs_sync,
};

/**
 * @}
 */