source: mainline/uspace/lib/libfs/libfs.c@ 253227a

/*
 * 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 libfs 
 * @{
 */ 
/**
 * @file
 * Glue code which is commonod to all FS implementations. 
 */

#include "libfs.h" 
#include "../../srv/vfs/vfs.h"
#include <errno.h>
#include <async.h>
#include <ipc/ipc.h>
#include <as.h>
#include <assert.h>
#include <dirent.h>

/** 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 vfs_phone     Open phone 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(int vfs_phone, 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.
         */
        ipc_call_t answer;
        aid_t req = async_send_0(vfs_phone, VFS_REGISTER, &answer);

        /*
         * Send our VFS info structure to VFS.
         */
        int rc = ipc_data_write_start(vfs_phone, info, sizeof(*info)); 
        if (rc != EOK) {
                async_wait_for(req, NULL);
                return rc;
        }

        /*
         * Ask VFS for callback connection.
         */
        ipc_connect_to_me(vfs_phone, 0, 0, 0, &reg->vfs_phonehash);

        /*
         * Allocate piece of address space for PLB.
         */
        reg->plb_ro = as_get_mappable_page(PLB_SIZE);
        if (!reg->plb_ro) {
                async_wait_for(req, NULL);
                return ENOMEM;
        }

        /*
         * Request sharing the Path Lookup Buffer with VFS.
         */
        rc = ipc_share_in_start_0_0(vfs_phone, reg->plb_ro, PLB_SIZE);
        if (rc) {
                async_wait_for(req, NULL);
                return rc;
        }
         
        /*
         * Pick up the answer for the request to the VFS_REQUEST call.
         */
        async_wait_for(req, NULL);
        reg->fs_handle = (int) IPC_GET_ARG1(answer);
        
        /*
         * Create a connection fibril to handle the callback connection.
         */
        async_new_connection(reg->vfs_phonehash, 0, NULL, conn);
        
        /*
         * 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);
}

/** 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_LOOKUP request.
 * @param request       VFS_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 next = IPC_GET_ARG1(*request);
        unsigned last = IPC_GET_ARG2(*request);
        dev_handle_t dev_handle = IPC_GET_ARG3(*request);
        int lflag = IPC_GET_ARG4(*request);
        fs_index_t index = IPC_GET_ARG5(*request); /* when L_LINK specified */
        char component[NAME_MAX + 1];
        int len;

        if (last < next)
                last += PLB_SIZE;

        void *par = NULL;
        void *cur = ops->root_get(dev_handle);
        void *tmp = NULL;

        if (ops->plb_get_char(next) == '/')
                next++;         /* eat slash */
        
        while (next <= last && ops->has_children(cur)) {
                /* collect the component */
                len = 0;
                while ((next <= last) &&  (ops->plb_get_char(next) != '/')) {
                        if (len + 1 == NAME_MAX) {
                                /* component length overflow */
                                ipc_answer_0(rid, ENAMETOOLONG);
                                goto out;
                        }
                        component[len++] = ops->plb_get_char(next);
                        next++; /* process next character */
                }

                assert(len);
                component[len] = '\0';
                next++;         /* eat slash */

                /* match the component */
                tmp = ops->match(cur, component);

                /* handle miss: match amongst siblings */
                if (!tmp) {
                        if (next <= last) {
                                /* there are unprocessed components */
                                ipc_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)) {
                                        ipc_answer_0(rid, ENOTDIR);
                                        goto out;
                                }
                                void *nodep;
                                if (lflag & L_CREATE)
                                        nodep = ops->create(lflag);
                                else
                                        nodep = ops->node_get(dev_handle,
                                            index);
                                if (nodep) {
                                        if (!ops->link(cur, nodep, component)) {
                                                if (lflag & L_CREATE) {
                                                        (void)ops->destroy(
                                                            nodep);
                                                }
                                                ipc_answer_0(rid, ENOSPC);
                                        } else {
                                                ipc_answer_5(rid, EOK,
                                                    fs_handle, dev_handle,
                                                    ops->index_get(nodep),
                                                    ops->size_get(nodep),
                                                    ops->lnkcnt_get(nodep));
                                                ops->node_put(nodep);
                                        }
                                } else {
                                        ipc_answer_0(rid, ENOSPC);
                                }
                                goto out;
                        } else if (lflag & L_PARENT) {
                                /* return parent */
                                ipc_answer_5(rid, EOK, fs_handle, dev_handle,
                                    ops->index_get(cur), ops->size_get(cur),
                                    ops->lnkcnt_get(cur));
                        } 
                        ipc_answer_0(rid, ENOENT);
                        goto out;
                }

                if (par)
                        ops->node_put(par);

                /* descend one level */
                par = cur;
                cur = tmp;
                tmp = NULL;
        }

        /* handle miss: excessive components */
        if (next <= last && !ops->has_children(cur)) {
                if (lflag & (L_CREATE | L_LINK)) {
                        if (!ops->is_directory(cur)) {
                                ipc_answer_0(rid, ENOTDIR);
                                goto out;
                        }

                        /* collect next component */
                        len = 0;
                        while (next <= last) {
                                if (ops->plb_get_char(next) == '/') {
                                        /* more than one component */
                                        ipc_answer_0(rid, ENOENT);
                                        goto out;
                                }
                                if (len + 1 == NAME_MAX) {
                                        /* component length overflow */
                                        ipc_answer_0(rid, ENAMETOOLONG);
                                        goto out;
                                }
                                component[len++] = ops->plb_get_char(next);
                                next++; /* process next character */
                        }
                        assert(len);
                        component[len] = '\0';
                                
                        void *nodep;
                        if (lflag & L_CREATE)
                                nodep = ops->create(lflag);
                        else
                                nodep = ops->node_get(dev_handle, index);
                        if (nodep) {
                                if (!ops->link(cur, nodep, component)) {
                                        if (lflag & L_CREATE)
                                                (void)ops->destroy(nodep);
                                        ipc_answer_0(rid, ENOSPC);
                                } else {
                                        ipc_answer_5(rid, EOK,
                                            fs_handle, dev_handle,
                                            ops->index_get(nodep),
                                            ops->size_get(nodep),
                                            ops->lnkcnt_get(nodep));
                                        ops->node_put(nodep);
                                }
                        } else {
                                ipc_answer_0(rid, ENOSPC);
                        }
                        goto out;
                }
                ipc_answer_0(rid, ENOENT);
                goto out;
        }

        /* handle hit */
        if (lflag & L_PARENT) {
                ops->node_put(cur);
                cur = par;
                par = NULL;
                if (!cur) {
                        ipc_answer_0(rid, ENOENT);
                        goto out;
                }
        }
        if (lflag & L_UNLINK) {
                unsigned old_lnkcnt = ops->lnkcnt_get(cur);
                int res = ops->unlink(par, cur);
                ipc_answer_5(rid, (ipcarg_t)res, fs_handle, dev_handle,
                    ops->index_get(cur), ops->size_get(cur), old_lnkcnt);
                goto out;
        }
        if (((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) ||
            (lflag & L_LINK)) {
                ipc_answer_0(rid, EEXIST);
                goto out;
        }
        if ((lflag & L_FILE) && (ops->is_directory(cur))) {
                ipc_answer_0(rid, EISDIR);
                goto out;
        }
        if ((lflag & L_DIRECTORY) && (ops->is_file(cur))) {
                ipc_answer_0(rid, ENOTDIR);
                goto out;
        }

        ipc_answer_5(rid, EOK, fs_handle, dev_handle, ops->index_get(cur),
            ops->size_get(cur), ops->lnkcnt_get(cur));

out:
        if (par)
                ops->node_put(par);
        if (cur)
                ops->node_put(cur);
        if (tmp)
                ops->node_put(tmp);
}

/** @}
 */