source: mainline/uspace/srv/fs/devfs/devfs_ops.c@ 25c60f4

/*
 * 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 fs
 * @{
 */

/**
 * @file devfs_ops.c
 * @brief Implementation of VFS operations for the devfs file system server.
 */

#include <macros.h>
#include <bool.h>
#include <errno.h>
#include <malloc.h>
#include <str.h>
#include <libfs.h>
#include <fibril_synch.h>
#include <adt/hash_table.h>
#include <ipc/devmap.h>
#include <sys/stat.h>
#include <libfs.h>
#include <assert.h>
#include "devfs.h"
#include "devfs_ops.h"

typedef struct {
        devmap_handle_type_t type;
        devmap_handle_t handle;
} devfs_node_t;

/** Opened devices structure */
typedef struct {
        devmap_handle_t handle;
        async_sess_t *sess;       /**< If NULL, the structure is incomplete. */
        size_t refcount;
        link_t link;
        fibril_condvar_t cv;      /**< Broadcast when completed. */
} device_t;

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

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

#define DEVICES_KEYS        1
#define DEVICES_KEY_HANDLE  0
#define DEVICES_BUCKETS     256

/* Implementation of hash table interface for the nodes hash table. */
static hash_index_t devices_hash(unsigned long key[])
{
        return key[DEVICES_KEY_HANDLE] % DEVICES_BUCKETS;
}

static int devices_compare(unsigned long key[], hash_count_t keys, link_t *item)
{
        device_t *dev = hash_table_get_instance(item, device_t, link);
        return (dev->handle == (devmap_handle_t) key[DEVICES_KEY_HANDLE]);
}

static void devices_remove_callback(link_t *item)
{
        free(hash_table_get_instance(item, device_t, link));
}

static hash_table_operations_t devices_ops = {
        .hash = devices_hash,
        .compare = devices_compare,
        .remove_callback = devices_remove_callback
};

static int devfs_node_get_internal(fs_node_t **rfn, devmap_handle_type_t type,
    devmap_handle_t handle)
{
        devfs_node_t *node = (devfs_node_t *) malloc(sizeof(devfs_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->handle = handle;
        
        (*rfn)->data = node;
        return EOK;
}

static int devfs_root_get(fs_node_t **rfn, devmap_handle_t devmap_handle)
{
        return devfs_node_get_internal(rfn, DEV_HANDLE_NONE, 0);
}

static int devfs_match(fs_node_t **rfn, fs_node_t *pfn, const char *component)
{
        devfs_node_t *node = (devfs_node_t *) pfn->data;
        int ret;
        
        if (node->handle == 0) {
                /* Root directory */
                
                dev_desc_t *devs;
                size_t count = devmap_get_namespaces(&devs);
                
                if (count > 0) {
                        size_t pos;
                        for (pos = 0; pos < count; pos++) {
                                /* Ignore root namespace */
                                if (str_cmp(devs[pos].name, "") == 0)
                                        continue;
                                
                                if (str_cmp(devs[pos].name, component) == 0) {
                                        ret = devfs_node_get_internal(rfn, DEV_HANDLE_NAMESPACE, devs[pos].handle);
                                        free(devs);
                                        return ret;
                                }
                        }
                        
                        free(devs);
                }
                
                /* Search root namespace */
                devmap_handle_t namespace;
                if (devmap_namespace_get_handle("", &namespace, 0) == EOK) {
                        count = devmap_get_devices(namespace, &devs);
                        
                        if (count > 0) {
                                size_t pos;
                                for (pos = 0; pos < count; pos++) {
                                        if (str_cmp(devs[pos].name, component) == 0) {
                                                ret = devfs_node_get_internal(rfn, DEV_HANDLE_DEVICE, devs[pos].handle);
                                                free(devs);
                                                return ret;
                                        }
                                }
                                
                                free(devs);
                        }
                }
                
                *rfn = NULL;
                return EOK;
        }
        
        if (node->type == DEV_HANDLE_NAMESPACE) {
                /* Namespace directory */
                
                dev_desc_t *devs;
                size_t count = devmap_get_devices(node->handle, &devs);
                if (count > 0) {
                        size_t pos;
                        for (pos = 0; pos < count; pos++) {
                                if (str_cmp(devs[pos].name, component) == 0) {
                                        ret = devfs_node_get_internal(rfn, DEV_HANDLE_DEVICE, devs[pos].handle);
                                        free(devs);
                                        return ret;
                                }
                        }
                        
                        free(devs);
                }
                
                *rfn = NULL;
                return EOK;
        }
        
        *rfn = NULL;
        return EOK;
}

static int devfs_node_get(fs_node_t **rfn, devmap_handle_t devmap_handle, fs_index_t index)
{
        return devfs_node_get_internal(rfn, devmap_handle_probe(index), index);
}

static int devfs_node_open(fs_node_t *fn)
{
        devfs_node_t *node = (devfs_node_t *) fn->data;
        
        if (node->handle == 0) {
                /* Root directory */
                return EOK;
        }
        
        devmap_handle_type_t type = devmap_handle_probe(node->handle);
        
        if (type == DEV_HANDLE_NAMESPACE) {
                /* Namespace directory */
                return EOK;
        }
        
        if (type == DEV_HANDLE_DEVICE) {
                /* Device node */
                
                unsigned long key[] = {
                        [DEVICES_KEY_HANDLE] = (unsigned long) node->handle
                };
                link_t *lnk;
                
                fibril_mutex_lock(&devices_mutex);
restart:
                lnk = hash_table_find(&devices, key);
                if (lnk == NULL) {
                        device_t *dev = (device_t *) malloc(sizeof(device_t));
                        if (dev == NULL) {
                                fibril_mutex_unlock(&devices_mutex);
                                return ENOMEM;
                        }
                        
                        dev->handle = node->handle;
                        
                        /* 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(&devices, key, &dev->link);
                        
                        /*
                         * Drop the mutex to allow recursive devfs requests.
                         */
                        fibril_mutex_unlock(&devices_mutex);
                        
                        async_sess_t *sess = devmap_device_connect(EXCHANGE_SERIALIZE,
                            node->handle, 0);
                        
                        fibril_mutex_lock(&devices_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(&devices, key, DEVICES_KEYS);
                                fibril_mutex_unlock(&devices_mutex);
                                
                                return ENOENT;
                        }
                        
                        /* Set the correct session. */
                        dev->sess = sess;
                } else {
                        device_t *dev = hash_table_get_instance(lnk, device_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, &devices_mutex);
                                goto restart;
                        }

                        dev->refcount++;
                }
                
                fibril_mutex_unlock(&devices_mutex);
                
                return EOK;
        }
        
        return ENOENT;
}

static int devfs_node_put(fs_node_t *fn)
{
        free(fn->data);
        free(fn);
        return EOK;
}

static int devfs_create_node(fs_node_t **rfn, devmap_handle_t devmap_handle, int lflag)
{
        assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
        
        *rfn = NULL;
        return ENOTSUP;
}

static int devfs_destroy_node(fs_node_t *fn)
{
        return ENOTSUP;
}

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

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

static int devfs_has_children(bool *has_children, fs_node_t *fn)
{
        devfs_node_t *node = (devfs_node_t *) fn->data;
        
        if (node->handle == 0) {
                size_t count = devmap_count_namespaces();
                if (count > 0) {
                        *has_children = true;
                        return EOK;
                }
                
                /* Root namespace */
                devmap_handle_t namespace;
                if (devmap_namespace_get_handle("", &namespace, 0) == EOK) {
                        count = devmap_count_devices(namespace);
                        if (count > 0) {
                                *has_children = true;
                                return EOK;
                        }
                }
                
                *has_children = false;
                return EOK;
        }
        
        if (node->type == DEV_HANDLE_NAMESPACE) {
                size_t count = devmap_count_devices(node->handle);
                if (count > 0) {
                        *has_children = true;
                        return EOK;
                }
                
                *has_children = false;
                return EOK;
        }
        
        *has_children = false;
        return EOK;
}

static fs_index_t devfs_index_get(fs_node_t *fn)
{
        devfs_node_t *node = (devfs_node_t *) fn->data;
        return node->handle;
}

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

static unsigned int devfs_lnkcnt_get(fs_node_t *fn)
{
        devfs_node_t *node = (devfs_node_t *) fn->data;
        
        if (node->handle == 0)
                return 0;
        
        return 1;
}

static bool devfs_is_directory(fs_node_t *fn)
{
        devfs_node_t *node = (devfs_node_t *) fn->data;
        
        return ((node->type == DEV_HANDLE_NONE) || (node->type == DEV_HANDLE_NAMESPACE));
}

static bool devfs_is_file(fs_node_t *fn)
{
        devfs_node_t *node = (devfs_node_t *) fn->data;
        
        return (node->type == DEV_HANDLE_DEVICE);
}

static devmap_handle_t devfs_device_get(fs_node_t *fn)
{
        devfs_node_t *node = (devfs_node_t *) fn->data;
        
        if (node->type == DEV_HANDLE_DEVICE)
                return node->handle;
        
        return 0;
}

/** libfs operations */
libfs_ops_t devfs_libfs_ops = {
        .root_get = devfs_root_get,
        .match = devfs_match,
        .node_get = devfs_node_get,
        .node_open = devfs_node_open,
        .node_put = devfs_node_put,
        .create = devfs_create_node,
        .destroy = devfs_destroy_node,
        .link = devfs_link_node,
        .unlink = devfs_unlink_node,
        .has_children = devfs_has_children,
        .index_get = devfs_index_get,
        .size_get = devfs_size_get,
        .lnkcnt_get = devfs_lnkcnt_get,
        .is_directory = devfs_is_directory,
        .is_file = devfs_is_file,
        .device_get = devfs_device_get
};

bool devfs_init(void)
{
        if (!hash_table_create(&devices, DEVICES_BUCKETS,
            DEVICES_KEYS, &devices_ops))
                return false;
        
        return true;
}

static int devfs_mounted(devmap_handle_t devmap_handle, const char *opts,
    fs_index_t *index, aoff64_t *size, unsigned *lnkcnt)
{
        *index = 0;
        *size = 0;
        *lnkcnt = 0;
        return EOK;
}

static int devfs_unmounted(devmap_handle_t devmap_handle)
{
        return ENOTSUP;
}

static int
devfs_read(devmap_handle_t devmap_handle, fs_index_t index, aoff64_t pos,
    size_t *rbytes)
{
        if (index == 0) {
                ipc_callid_t callid;
                size_t size;
                if (!async_data_read_receive(&callid, &size)) {
                        async_answer_0(callid, EINVAL);
                        return EINVAL;
                }
                
                dev_desc_t *desc;
                size_t count = devmap_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(callid, desc[pos].name, str_size(desc[pos].name) + 1);
                        free(desc);
                        *rbytes = 1;
                        return EOK;
                }
                
                free(desc);
                pos -= count;
                
                /* Search root namespace */
                devmap_handle_t namespace;
                if (devmap_namespace_get_handle("", &namespace, 0) == EOK) {
                        count = devmap_get_devices(namespace, &desc);
                        
                        if (pos < count) {
                                async_data_read_finalize(callid, desc[pos].name, str_size(desc[pos].name) + 1);
                                free(desc);
                                *rbytes = 1;
                                return EOK;
                        }
                        
                        free(desc);
                }
                
                async_answer_0(callid, ENOENT);
                return ENOENT;
        }
        
        devmap_handle_type_t type = devmap_handle_probe(index);
        
        if (type == DEV_HANDLE_NAMESPACE) {
                /* Namespace directory */
                ipc_callid_t callid;
                size_t size;
                if (!async_data_read_receive(&callid, &size)) {
                        async_answer_0(callid, EINVAL);
                        return EINVAL;
                }
                
                dev_desc_t *desc;
                size_t count = devmap_get_devices(index, &desc);
                
                if (pos < count) {
                        async_data_read_finalize(callid, desc[pos].name, str_size(desc[pos].name) + 1);
                        free(desc);
                        *rbytes = 1;
                        return EOK;
                }
                
                free(desc);
                async_answer_0(callid, ENOENT);
                return ENOENT;
        }
        
        if (type == DEV_HANDLE_DEVICE) {
                /* Device node */
                
                unsigned long key[] = {
                        [DEVICES_KEY_HANDLE] = (unsigned long) index
                };
                
                fibril_mutex_lock(&devices_mutex);
                link_t *lnk = hash_table_find(&devices, key);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&devices_mutex);
                        return ENOENT;
                }
                
                device_t *dev = hash_table_get_instance(lnk, device_t, link);
                assert(dev->sess);
                
                ipc_callid_t callid;
                if (!async_data_read_receive(&callid, NULL)) {
                        fibril_mutex_unlock(&devices_mutex);
                        async_answer_0(callid, 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, devmap_handle,
                    index, LOWER32(pos), UPPER32(pos), &answer);
                
                /* Forward the IPC_M_DATA_READ request to the driver */
                async_forward_fast(callid, exch, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
                
                async_exchange_end(exch);
                
                fibril_mutex_unlock(&devices_mutex);
                
                /* Wait for reply from the driver. */
                sysarg_t rc;
                async_wait_for(msg, &rc);
                
                *rbytes = IPC_GET_ARG1(answer);
                return rc;
        }
        
        return ENOENT;
}

static int
devfs_write(devmap_handle_t devmap_handle, fs_index_t index, aoff64_t pos,
    size_t *wbytes, aoff64_t *nsize)
{
        if (index == 0)
                return ENOTSUP;
        
        devmap_handle_type_t type = devmap_handle_probe(index);
        
        if (type == DEV_HANDLE_NAMESPACE) {
                /* Namespace directory */
                return ENOTSUP;
        }
        
        if (type == DEV_HANDLE_DEVICE) {
                /* Device node */
                unsigned long key[] = {
                        [DEVICES_KEY_HANDLE] = (unsigned long) index
                };
                
                fibril_mutex_lock(&devices_mutex);
                link_t *lnk = hash_table_find(&devices, key);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&devices_mutex);
                        return ENOENT;
                }
                
                device_t *dev = hash_table_get_instance(lnk, device_t, link);
                assert(dev->sess);
                
                ipc_callid_t callid;
                if (!async_data_write_receive(&callid, NULL)) {
                        fibril_mutex_unlock(&devices_mutex);
                        async_answer_0(callid, 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, devmap_handle,
                    index, LOWER32(pos), UPPER32(pos), &answer);
                
                /* Forward the IPC_M_DATA_WRITE request to the driver */
                async_forward_fast(callid, exch, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
                
                async_exchange_end(exch);
                
                fibril_mutex_unlock(&devices_mutex);
                
                /* Wait for reply from the driver. */
                sysarg_t rc;
                async_wait_for(msg, &rc);
                
                *wbytes = IPC_GET_ARG1(answer);
                *nsize = 0;
                return rc;
        }
        
        return ENOENT;
}

static int
devfs_truncate(devmap_handle_t devmap_handle, fs_index_t index, aoff64_t size)
{
        return ENOTSUP;
}

static int devfs_close(devmap_handle_t devmap_handle, fs_index_t index)
{
        if (index == 0)
                return EOK;
        
        devmap_handle_type_t type = devmap_handle_probe(index);
        
        if (type == DEV_HANDLE_NAMESPACE) {
                /* Namespace directory */
                return EOK;
        }
        
        if (type == DEV_HANDLE_DEVICE) {
                unsigned long key[] = {
                        [DEVICES_KEY_HANDLE] = (unsigned long) index
                };
                
                fibril_mutex_lock(&devices_mutex);
                link_t *lnk = hash_table_find(&devices, key);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&devices_mutex);
                        return ENOENT;
                }
                
                device_t *dev = hash_table_get_instance(lnk, device_t, link);
                assert(dev->sess);
                dev->refcount--;
                
                if (dev->refcount == 0) {
                        async_hangup(dev->sess);
                        hash_table_remove(&devices, key, DEVICES_KEYS);
                }
                
                fibril_mutex_unlock(&devices_mutex);
                
                return EOK;
        }
        
        return ENOENT;
}

static int devfs_sync(devmap_handle_t devmap_handle, fs_index_t index)
{
        if (index == 0)
                return EOK;
        
        devmap_handle_type_t type = devmap_handle_probe(index);
        
        if (type == DEV_HANDLE_NAMESPACE) {
                /* Namespace directory */
                return EOK;
        }
        
        if (type == DEV_HANDLE_DEVICE) {
                unsigned long key[] = {
                        [DEVICES_KEY_HANDLE] = (unsigned long) index
                };
                
                fibril_mutex_lock(&devices_mutex);
                link_t *lnk = hash_table_find(&devices, key);
                if (lnk == NULL) {
                        fibril_mutex_unlock(&devices_mutex);
                        return ENOENT;
                }
                
                device_t *dev = hash_table_get_instance(lnk, device_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, devmap_handle,
                    index, &answer);
                
                async_exchange_end(exch);
                
                fibril_mutex_unlock(&devices_mutex);
                
                /* Wait for reply from the driver */
                sysarg_t rc;
                async_wait_for(msg, &rc);
                
                return rc;
        }
        
        return  ENOENT;
}

static int devfs_destroy(devmap_handle_t devmap_handle, fs_index_t index)
{
        return ENOTSUP;
}

vfs_out_ops_t devfs_ops = {
        .mounted = devfs_mounted,
        .unmounted = devfs_unmounted,
        .read = devfs_read,
        .write = devfs_write,
        .truncate = devfs_truncate,
        .close = devfs_close,
        .destroy = devfs_destroy,
        .sync = devfs_sync,
};

/**
 * @}
 */