source: mainline/uspace/lib/fs/libfs.c@ 1d1bb0f

/*
 * Copyright (c) 2009 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 libfs
 * @{
 */
/**
 * @file
 * Glue code which is common to all FS implementations.
 */

#include "libfs.h"
#include "../../srv/vfs/vfs.h"
#include <macros.h>
#include <errno.h>
#include <async.h>
#include <as.h>
#include <assert.h>
#include <dirent.h>
#include <mem.h>
#include <sys/stat.h>

#define on_error(rc, action) \
        do { \
                if ((rc) != EOK) \
                        action; \
        } while (0)

#define combine_rc(rc1, rc2) \
        ((rc1) == EOK ? (rc2) : (rc1))

#define answer_and_return(rid, rc) \
        do { \
                async_answer_0((rid), (rc)); \
                return; \
        } while (0)

/** Register file system server.
 *
 * This function abstracts away the tedious registration protocol from
 * file system implementations and lets them to reuse this registration glue
 * code.
 *
 * @param sess Session for communication with VFS.
 * @param reg  File system registration structure. It will be
 *             initialized by this function.
 * @param info VFS info structure supplied by the file system
 *             implementation.
 * @param conn Connection fibril for handling all calls originating in
 *             VFS.
 *
 * @return EOK on success or a non-zero error code on errror.
 *
 */
int fs_register(async_sess_t *sess, fs_reg_t *reg, vfs_info_t *info,
    async_client_conn_t conn)
{
        /*
         * Tell VFS that we are here and want to get registered.
         * We use the async framework because VFS will answer the request
         * out-of-order, when it knows that the operation succeeded or failed.
         */
        
        async_exch_t *exch = async_exchange_begin(sess);
        
        ipc_call_t answer;
        aid_t req = async_send_0(exch, VFS_IN_REGISTER, &answer);
        
        /*
         * Send our VFS info structure to VFS.
         */
        int rc = async_data_write_start(exch, info, sizeof(*info));
        
        if (rc != EOK) {
                async_exchange_end(exch);
                async_wait_for(req, NULL);
                return rc;
        }
        
        /*
         * Ask VFS for callback connection.
         */
        async_connect_to_me(exch, 0, 0, 0, conn, NULL);
        
        /*
         * Allocate piece of address space for PLB.
         */
        reg->plb_ro = as_get_mappable_page(PLB_SIZE);
        if (!reg->plb_ro) {
                async_exchange_end(exch);
                async_wait_for(req, NULL);
                return ENOMEM;
        }
        
        /*
         * Request sharing the Path Lookup Buffer with VFS.
         */
        rc = async_share_in_start_0_0(exch, reg->plb_ro, PLB_SIZE);
        
        async_exchange_end(exch);
        
        if (rc) {
                async_wait_for(req, NULL);
                return rc;
        }
         
        /*
         * Pick up the answer for the request to the VFS_IN_REQUEST call.
         */
        async_wait_for(req, NULL);
        reg->fs_handle = (int) IPC_GET_ARG1(answer);
        
        /*
         * Tell the async framework that other connections are to be handled by
         * the same connection fibril as well.
         */
        async_set_client_connection(conn);
        
        return IPC_GET_RETVAL(answer);
}

void fs_node_initialize(fs_node_t *fn)
{
        memset(fn, 0, sizeof(fs_node_t));
}

void libfs_mount(libfs_ops_t *ops, fs_handle_t fs_handle, ipc_callid_t rid,
    ipc_call_t *request)
{
        devmap_handle_t mp_devmap_handle = (devmap_handle_t) IPC_GET_ARG1(*request);
        fs_index_t mp_fs_index = (fs_index_t) IPC_GET_ARG2(*request);
        fs_handle_t mr_fs_handle = (fs_handle_t) IPC_GET_ARG3(*request);
        devmap_handle_t mr_devmap_handle = (devmap_handle_t) IPC_GET_ARG4(*request);
        
        async_sess_t *mountee_sess = async_clone_receive(EXCHANGE_PARALLEL);
        if (mountee_sess == NULL) {
                async_answer_0(rid, EINVAL);
                return;
        }
        
        fs_node_t *fn;
        int res = ops->node_get(&fn, mp_devmap_handle, mp_fs_index);
        if ((res != EOK) || (!fn)) {
                async_hangup(mountee_sess);
                async_data_write_void(combine_rc(res, ENOENT));
                async_answer_0(rid, combine_rc(res, ENOENT));
                return;
        }
        
        if (fn->mp_data.mp_active) {
                async_hangup(mountee_sess);
                (void) ops->node_put(fn);
                async_data_write_void(EBUSY);
                async_answer_0(rid, EBUSY);
                return;
        }
        
        async_exch_t *exch = async_exchange_begin(mountee_sess);
        async_sess_t *sess = async_connect_me(EXCHANGE_PARALLEL, exch);
        
        if (!sess) {
                async_exchange_end(exch);
                async_hangup(mountee_sess);
                (void) ops->node_put(fn);
                async_data_write_void(errno);
                async_answer_0(rid, errno);
                return;
        }
        
        ipc_call_t answer;
        int rc = async_data_write_forward_1_1(exch, VFS_OUT_MOUNTED,
            mr_devmap_handle, &answer);
        async_exchange_end(exch);
        
        if (rc == EOK) {
                fn->mp_data.mp_active = true;
                fn->mp_data.fs_handle = mr_fs_handle;
                fn->mp_data.devmap_handle = mr_devmap_handle;
                fn->mp_data.sess = mountee_sess;
        }
        
        /*
         * Do not release the FS node so that it stays in memory.
         */
        async_answer_3(rid, rc, IPC_GET_ARG1(answer), IPC_GET_ARG2(answer),
            IPC_GET_ARG3(answer));
}

void libfs_unmount(libfs_ops_t *ops, ipc_callid_t rid, ipc_call_t *request)
{
        devmap_handle_t mp_devmap_handle = (devmap_handle_t) IPC_GET_ARG1(*request);
        fs_index_t mp_fs_index = (fs_index_t) IPC_GET_ARG2(*request);
        fs_node_t *fn;
        int res;

        res = ops->node_get(&fn, mp_devmap_handle, mp_fs_index);
        if ((res != EOK) || (!fn)) {
                async_answer_0(rid, combine_rc(res, ENOENT));
                return;
        }

        /*
         * We are clearly expecting to find the mount point active.
         */
        if (!fn->mp_data.mp_active) {
                (void) ops->node_put(fn);
                async_answer_0(rid, EINVAL);
                return;
        }

        /*
         * Tell the mounted file system to unmount.
         */
        async_exch_t *exch = async_exchange_begin(fn->mp_data.sess);
        res = async_req_1_0(exch, VFS_OUT_UNMOUNTED, fn->mp_data.devmap_handle);
        async_exchange_end(exch);

        /*
         * If everything went well, perform the clean-up on our side.
         */
        if (res == EOK) {
                async_hangup(fn->mp_data.sess);
                fn->mp_data.mp_active = false;
                fn->mp_data.fs_handle = 0;
                fn->mp_data.devmap_handle = 0;
                fn->mp_data.sess = NULL;
                
                /* Drop the reference created in libfs_mount(). */
                (void) ops->node_put(fn);
        }

        (void) ops->node_put(fn);
        async_answer_0(rid, res);
}

/** Lookup VFS triplet by name in the file system name space.
 *
 * The path passed in the PLB must be in the canonical file system path format
 * as returned by the canonify() function.
 *
 * @param ops       libfs operations structure with function pointers to
 *                  file system implementation
 * @param fs_handle File system handle of the file system where to perform
 *                  the lookup.
 * @param rid       Request ID of the VFS_OUT_LOOKUP request.
 * @param request   VFS_OUT_LOOKUP request data itself.
 *
 */
void libfs_lookup(libfs_ops_t *ops, fs_handle_t fs_handle, ipc_callid_t rid,
    ipc_call_t *request)
{
        unsigned int first = IPC_GET_ARG1(*request);
        unsigned int last = IPC_GET_ARG2(*request);
        unsigned int next = first;
        devmap_handle_t devmap_handle = IPC_GET_ARG3(*request);
        int lflag = IPC_GET_ARG4(*request);
        fs_index_t index = IPC_GET_ARG5(*request);
        char component[NAME_MAX + 1];
        int len;
        int rc;
        
        if (last < next)
                last += PLB_SIZE;
        
        fs_node_t *par = NULL;
        fs_node_t *cur = NULL;
        fs_node_t *tmp = NULL;
        
        rc = ops->root_get(&cur, devmap_handle);
        on_error(rc, goto out_with_answer);
        
        if (cur->mp_data.mp_active) {
                async_exch_t *exch = async_exchange_begin(cur->mp_data.sess);
                async_forward_slow(rid, exch, VFS_OUT_LOOKUP, next, last,
                    cur->mp_data.devmap_handle, lflag, index, IPC_FF_ROUTE_FROM_ME);
                async_exchange_end(exch);
                
                (void) ops->node_put(cur);
                return;
        }
        
        /* Eat slash */
        if (ops->plb_get_char(next) == '/')
                next++;
        
        while (next <= last) {
                bool has_children;
                
                rc = ops->has_children(&has_children, cur);
                on_error(rc, goto out_with_answer);
                if (!has_children)
                        break;
                
                /* Collect the component */
                len = 0;
                while ((next <= last) && (ops->plb_get_char(next) != '/')) {
                        if (len + 1 == NAME_MAX) {
                                /* Component length overflow */
                                async_answer_0(rid, ENAMETOOLONG);
                                goto out;
                        }
                        component[len++] = ops->plb_get_char(next);
                        /* Process next character */
                        next++;
                }
                
                assert(len);
                component[len] = '\0';
                /* Eat slash */
                next++;
                
                /* Match the component */
                rc = ops->match(&tmp, cur, component);
                on_error(rc, goto out_with_answer);
                
                /*
                 * If the matching component is a mount point, there are two
                 * legitimate semantics of the lookup operation. The first is
                 * the commonly used one in which the lookup crosses each mount
                 * point into the mounted file system. The second semantics is
                 * used mostly during unmount() and differs from the first one
                 * only in that the last mount point in the looked up path,
                 * which is also its last component, is not crossed.
                 */

                if ((tmp) && (tmp->mp_data.mp_active) &&
                    (!(lflag & L_MP) || (next <= last))) {
                        if (next > last)
                                next = last = first;
                        else
                                next--;
                        
                        async_exch_t *exch = async_exchange_begin(tmp->mp_data.sess);
                        async_forward_slow(rid, exch, VFS_OUT_LOOKUP, next, last,
                            tmp->mp_data.devmap_handle, lflag, index,
                            IPC_FF_ROUTE_FROM_ME);
                        async_exchange_end(exch);
                        
                        (void) ops->node_put(cur);
                        (void) ops->node_put(tmp);
                        if (par)
                                (void) ops->node_put(par);
                        return;
                }
                
                /* Handle miss: match amongst siblings */
                if (!tmp) {
                        if (next <= last) {
                                /* There are unprocessed components */
                                async_answer_0(rid, ENOENT);
                                goto out;
                        }
                        
                        /* Miss in the last component */
                        if (lflag & (L_CREATE | L_LINK)) {
                                /* Request to create a new link */
                                if (!ops->is_directory(cur)) {
                                        async_answer_0(rid, ENOTDIR);
                                        goto out;
                                }
                                
                                fs_node_t *fn;
                                if (lflag & L_CREATE)
                                        rc = ops->create(&fn, devmap_handle,
                                            lflag);
                                else
                                        rc = ops->node_get(&fn, devmap_handle,
                                            index);
                                on_error(rc, goto out_with_answer);
                                
                                if (fn) {
                                        rc = ops->link(cur, fn, component);
                                        if (rc != EOK) {
                                                if (lflag & L_CREATE)
                                                        (void) ops->destroy(fn);
                                                else
                                                        (void) ops->node_put(fn);
                                                async_answer_0(rid, rc);
                                        } else {
                                                aoff64_t size = ops->size_get(fn);
                                                async_answer_5(rid, fs_handle,
                                                    devmap_handle,
                                                    ops->index_get(fn),
                                                    LOWER32(size),
                                                    UPPER32(size),
                                                    ops->lnkcnt_get(fn));
                                                (void) ops->node_put(fn);
                                        }
                                } else
                                        async_answer_0(rid, ENOSPC);
                                
                                goto out;
                        }
                        
                        async_answer_0(rid, ENOENT);
                        goto out;
                }
                
                if (par) {
                        rc = ops->node_put(par);
                        on_error(rc, goto out_with_answer);
                }
                
                /* Descend one level */
                par = cur;
                cur = tmp;
                tmp = NULL;
        }
        
        /* Handle miss: excessive components */
        if (next <= last) {
                bool has_children;
                rc = ops->has_children(&has_children, cur);
                on_error(rc, goto out_with_answer);
                
                if (has_children)
                        goto skip_miss;
                
                if (lflag & (L_CREATE | L_LINK)) {
                        if (!ops->is_directory(cur)) {
                                async_answer_0(rid, ENOTDIR);
                                goto out;
                        }
                        
                        /* Collect next component */
                        len = 0;
                        while (next <= last) {
                                if (ops->plb_get_char(next) == '/') {
                                        /* More than one component */
                                        async_answer_0(rid, ENOENT);
                                        goto out;
                                }
                                
                                if (len + 1 == NAME_MAX) {
                                        /* Component length overflow */
                                        async_answer_0(rid, ENAMETOOLONG);
                                        goto out;
                                }
                                
                                component[len++] = ops->plb_get_char(next);
                                /* Process next character */
                                next++;
                        }
                        
                        assert(len);
                        component[len] = '\0';
                        
                        fs_node_t *fn;
                        if (lflag & L_CREATE)
                                rc = ops->create(&fn, devmap_handle, lflag);
                        else
                                rc = ops->node_get(&fn, devmap_handle, index);
                        on_error(rc, goto out_with_answer);
                        
                        if (fn) {
                                rc = ops->link(cur, fn, component);
                                if (rc != EOK) {
                                        if (lflag & L_CREATE)
                                                (void) ops->destroy(fn);
                                        else
                                                (void) ops->node_put(fn);
                                        async_answer_0(rid, rc);
                                } else {
                                        aoff64_t size = ops->size_get(fn);
                                        async_answer_5(rid, fs_handle,
                                            devmap_handle,
                                            ops->index_get(fn),
                                            LOWER32(size),
                                            UPPER32(size),
                                            ops->lnkcnt_get(fn));
                                        (void) ops->node_put(fn);
                                }
                        } else
                                async_answer_0(rid, ENOSPC);
                        
                        goto out;
                }
                
                async_answer_0(rid, ENOENT);
                goto out;
        }
        
skip_miss:
        
        /* Handle hit */
        if (lflag & L_UNLINK) {
                unsigned int old_lnkcnt = ops->lnkcnt_get(cur);
                rc = ops->unlink(par, cur, component);
                
                if (rc == EOK) {
                        aoff64_t size = ops->size_get(cur);
                        async_answer_5(rid, fs_handle, devmap_handle,
                            ops->index_get(cur), LOWER32(size), UPPER32(size),
                            old_lnkcnt);
                } else
                        async_answer_0(rid, rc);
                
                goto out;
        }
        
        if (((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) ||
            (lflag & L_LINK)) {
                async_answer_0(rid, EEXIST);
                goto out;
        }
        
        if ((lflag & L_FILE) && (ops->is_directory(cur))) {
                async_answer_0(rid, EISDIR);
                goto out;
        }
        
        if ((lflag & L_DIRECTORY) && (ops->is_file(cur))) {
                async_answer_0(rid, ENOTDIR);
                goto out;
        }

        if ((lflag & L_ROOT) && par) {
                async_answer_0(rid, EINVAL);
                goto out;
        }
        
out_with_answer:
        
        if (rc == EOK) {
                if (lflag & L_OPEN)
                        rc = ops->node_open(cur);
                
                if (rc == EOK) {
                        aoff64_t size = ops->size_get(cur);
                        async_answer_5(rid, fs_handle, devmap_handle,
                            ops->index_get(cur), LOWER32(size), UPPER32(size),
                            ops->lnkcnt_get(cur));
                } else
                        async_answer_0(rid, rc);
                
        } else
                async_answer_0(rid, rc);
        
out:
        
        if (par)
                (void) ops->node_put(par);
        
        if (cur)
                (void) ops->node_put(cur);
        
        if (tmp)
                (void) ops->node_put(tmp);
}

void libfs_stat(libfs_ops_t *ops, fs_handle_t fs_handle, ipc_callid_t rid,
    ipc_call_t *request)
{
        devmap_handle_t devmap_handle = (devmap_handle_t) IPC_GET_ARG1(*request);
        fs_index_t index = (fs_index_t) IPC_GET_ARG2(*request);
        
        fs_node_t *fn;
        int rc = ops->node_get(&fn, devmap_handle, index);
        on_error(rc, answer_and_return(rid, rc));
        
        ipc_callid_t callid;
        size_t size;
        if ((!async_data_read_receive(&callid, &size)) ||
            (size != sizeof(struct stat))) {
                ops->node_put(fn);
                async_answer_0(callid, EINVAL);
                async_answer_0(rid, EINVAL);
                return;
        }
        
        struct stat stat;
        memset(&stat, 0, sizeof(struct stat));
        
        stat.fs_handle = fs_handle;
        stat.devmap_handle = devmap_handle;
        stat.index = index;
        stat.lnkcnt = ops->lnkcnt_get(fn);
        stat.is_file = ops->is_file(fn);
        stat.is_directory = ops->is_directory(fn);
        stat.size = ops->size_get(fn);
        stat.device = ops->device_get(fn);
        
        ops->node_put(fn);
        
        async_data_read_finalize(callid, &stat, sizeof(struct stat));
        async_answer_0(rid, EOK);
}

/** Open VFS triplet.
 *
 * @param ops     libfs operations structure with function pointers to
 *                file system implementation
 * @param rid     Request ID of the VFS_OUT_OPEN_NODE request.
 * @param request VFS_OUT_OPEN_NODE request data itself.
 *
 */
void libfs_open_node(libfs_ops_t *ops, fs_handle_t fs_handle, ipc_callid_t rid,
    ipc_call_t *request)
{
        devmap_handle_t devmap_handle = IPC_GET_ARG1(*request);
        fs_index_t index = IPC_GET_ARG2(*request);
        
        fs_node_t *fn;
        int rc = ops->node_get(&fn, devmap_handle, index);
        on_error(rc, answer_and_return(rid, rc));
        
        if (fn == NULL) {
                async_answer_0(rid, ENOENT);
                return;
        }
        
        rc = ops->node_open(fn);
        aoff64_t size = ops->size_get(fn);
        async_answer_4(rid, rc, LOWER32(size), UPPER32(size), ops->lnkcnt_get(fn),
            (ops->is_file(fn) ? L_FILE : 0) | (ops->is_directory(fn) ? L_DIRECTORY : 0));
        
        (void) ops->node_put(fn);
}

/** @}
 */