source: mainline/uspace/srv/fs/minixfs/mfs_dentry.c@ 6f7e0cd

/*
 * Copyright (c) 2011 Maurizio Lombardi
 * 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
 * @{
 */

#include "mfs.h"

/**Read a directory entry from disk.
 *
 * @param mnode         Pointer to the directory node.
 * @param d_info        Pointer to a directory entry structure where the dentry info
 *                      will be stored.
 * @param index         index of the dentry in the list.
 *
 * @return              EOK on success or a negative error code.
 */
int
read_dentry(struct mfs_node *mnode,
                     struct mfs_dentry_info *d_info, unsigned index)
{
        const struct mfs_instance *inst = mnode->instance;
        const struct mfs_sb_info *sbi = inst->sbi;
        const bool longnames = sbi->long_names;
        uint32_t block;
        block_t *b;

        int r = read_map(&block, mnode, index * sbi->dirsize);
        on_error(r, goto out_err);

        if (block == 0) {
                /*End of the dentries list*/
                r = EOK;
                goto out_err;
        }

        r = block_get(&b, inst->handle, block, BLOCK_FLAGS_NONE);
        on_error(r, goto out_err);

        unsigned dentries_per_zone = sbi->block_size / sbi->dirsize;
        unsigned dentry_off = index % dentries_per_zone;

        if (sbi->fs_version == MFS_VERSION_V3) {
                struct mfs3_dentry *d3;

                d3 = b->data + (dentry_off * MFS3_DIRSIZE);

                d_info->d_inum = conv32(sbi->native, d3->d_inum);
                memcpy(d_info->d_name, d3->d_name, MFS3_MAX_NAME_LEN);
        } else {
                const int namelen = longnames ? MFS_L_MAX_NAME_LEN :
                                    MFS_MAX_NAME_LEN;

                struct mfs_dentry *d;

                d = b->data + dentry_off * (longnames ? MFSL_DIRSIZE :
                                            MFS_DIRSIZE);
                d_info->d_inum = conv16(sbi->native, d->d_inum);
                memcpy(d_info->d_name, d->d_name, namelen);
        }

        r = block_put(b);

        d_info->index = index;
        d_info->node = mnode;

out_err:
        return r;
}

/**Write a directory entry on disk.
 *
 * @param d_info        Pointer to the directory entry structure to write on disk.
 *
 * @return              EOK on success or a negative error code.
 */
int
write_dentry(struct mfs_dentry_info *d_info)
{
        struct mfs_node *mnode = d_info->node;
        struct mfs_sb_info *sbi = mnode->instance->sbi;
        const unsigned d_off_bytes = d_info->index * sbi->dirsize;
        const unsigned dirs_per_block = sbi->block_size / sbi->dirsize;
        block_t *b;
        uint32_t block;
        int r;

        r = read_map(&block, mnode, d_off_bytes);
        on_error(r, goto out);

        r = block_get(&b, mnode->instance->handle, block, BLOCK_FLAGS_NONE);
        on_error(r, goto out);

        const size_t name_len = sbi->max_name_len;
        uint8_t *ptr = b->data;
        ptr += (d_info->index % dirs_per_block) * sbi->dirsize;

        if (sbi->fs_version == MFS_VERSION_V3) {
                struct mfs3_dentry *dentry;
                dentry = (struct mfs3_dentry *) ptr;

                dentry->d_inum = conv32(sbi->native, d_info->d_inum);
                memcpy(dentry->d_name, d_info->d_name, name_len);
        } else {
                struct mfs_dentry *dentry;
                dentry = (struct mfs_dentry *) ptr;

                dentry->d_inum = conv16(sbi->native, d_info->d_inum);
                memcpy(dentry->d_name, d_info->d_name, name_len);
        }

        b->dirty = true;
        r = block_put(b);

out:
        return r;
}

/**Remove a directory entry from a directory.
 *
 * @param mnode         Pointer to the directory node.
 * @param d_name        Name of the directory entry to delete.
 *
 * @return              EOK on success or a negative error code.
 */
int
remove_dentry(struct mfs_node *mnode, const char *d_name)
{
        struct mfs_sb_info *sbi = mnode->instance->sbi;
        struct mfs_dentry_info d_info;
        int r;

        const size_t name_len = str_size(d_name);

        if (name_len > sbi->max_name_len)
                return ENAMETOOLONG;

        /*Search the directory entry to be removed*/
        unsigned i;
        for (i = 0; i < mnode->ino_i->i_size / sbi->dirsize ; ++i) {
                r = read_dentry(mnode, &d_info, i);
                on_error(r, return r);

                if (!bcmp(d_info.d_name, d_name, name_len)) {
                        d_info.d_inum = 0;
                        r = write_dentry(&d_info);
                        return r;
                }
        }

        return ENOENT;
}

/**Insert a new directory entry in a existing directory.
 *
 * @param mnode         Pointer to the directory node.
 * @param d_name        Name of the new directory entry.
 * @param d_inum        index of the inode that will be pointed by the new dentry.
 *
 * @return              EOK on success or a negative error code.
 */
int
insert_dentry(struct mfs_node *mnode, const char *d_name, fs_index_t d_inum)
{
        int r;
        struct mfs_sb_info *sbi = mnode->instance->sbi;
        struct mfs_dentry_info d_info;
        bool empty_dentry_found = false;

        const size_t name_len = str_size(d_name);

        if (name_len > sbi->max_name_len)
                return ENAMETOOLONG;

        /*Search for an empty dentry*/
        unsigned i;
        for (i = 0; i < mnode->ino_i->i_size / sbi->dirsize; ++i) {
                r = read_dentry(mnode, &d_info, i);
                on_error(r, return r);

                if (d_info.d_inum == 0) {
                        /*This entry is not used*/
                        empty_dentry_found = true;
                        break;
                }
        }

        if (!empty_dentry_found) {
                uint32_t b, pos;
                pos = mnode->ino_i->i_size;
                r = read_map(&b, mnode, pos);
                on_error(r, goto out);

                if (b == 0) {
                        /*Increase the inode size*/

                        uint32_t dummy;
                        r = mfs_alloc_zone(mnode->instance, &b);
                        on_error(r, goto out);
                        r = write_map(mnode, pos, b, &dummy);
                        on_error(r, goto out);
                }

                mnode->ino_i->i_size += sbi->dirsize;
                mnode->ino_i->dirty = true;

                d_info.index = i;
                d_info.node = mnode;
        }

        d_info.d_inum = d_inum;
        memcpy(d_info.d_name, d_name, name_len);
        d_info.d_name[name_len] = 0;

        r = write_dentry(&d_info);
out:
        return r;
}


/**
 * @}
 */