/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * Copyright (c) 2012-2013 Red Hat, Inc.
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_shared.h"
#include "xfs_trans_resv.h"
#include "xfs_ag.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_inode.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_symlink.h"
#include "xfs_cksum.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"


/*
 * Each contiguous block has a header, so it is not just a simple pathlen
 * to FSB conversion.
 */
int
xfs_symlink_blocks(
        struct xfs_mount *mp,
        int             pathlen)
{
        int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);

        return (pathlen + buflen - 1) / buflen;
}

int
xfs_symlink_hdr_set(
        struct xfs_mount        *mp,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        struct xfs_buf          *bp)
{
        struct xfs_dsymlink_hdr *dsl = bp->b_addr;

        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return 0;

        dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
        dsl->sl_offset = cpu_to_be32(offset);
        dsl->sl_bytes = cpu_to_be32(size);
        uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
        dsl->sl_owner = cpu_to_be64(ino);
        dsl->sl_blkno = cpu_to_be64(bp->b_bn);
        bp->b_ops = &xfs_symlink_buf_ops;

        return sizeof(struct xfs_dsymlink_hdr);
}

/*
 * Checking of the symlink header is split into two parts. the verifier does
 * CRC, location and bounds checking, the unpacking function checks the path
 * parameters and owner.
 */
bool
xfs_symlink_hdr_ok(
        struct xfs_mount        *mp,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        struct xfs_buf          *bp)
{
        struct xfs_dsymlink_hdr *dsl = bp->b_addr;

        if (offset != be32_to_cpu(dsl->sl_offset))
                return false;
        if (size != be32_to_cpu(dsl->sl_bytes))
                return false;
        if (ino != be64_to_cpu(dsl->sl_owner))
                return false;

        /* ok */
        return true;
}

static bool
xfs_symlink_verify(
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = bp->b_target->bt_mount;
        struct xfs_dsymlink_hdr *dsl = bp->b_addr;

        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return false;
        if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
                return false;
        if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
                return false;
        if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
                return false;
        if (be32_to_cpu(dsl->sl_offset) +
                                be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
                return false;
        if (dsl->sl_owner == 0)
                return false;

        return true;
}

static void
xfs_symlink_read_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_target->bt_mount;

        /* no verification of non-crc buffers */
        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return;

        if (!xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
                                  offsetof(struct xfs_dsymlink_hdr, sl_crc)) ||
            !xfs_symlink_verify(bp)) {
                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
                xfs_buf_ioerror(bp, EFSCORRUPTED);
        }
}

static void
xfs_symlink_write_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_target->bt_mount;
        struct xfs_buf_log_item *bip = bp->b_fspriv;

        /* no verification of non-crc buffers */
        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return;

        if (!xfs_symlink_verify(bp)) {
                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
                xfs_buf_ioerror(bp, EFSCORRUPTED);
                return;
        }

        if (bip) {
                struct xfs_dsymlink_hdr *dsl = bp->b_addr;
                dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
        }
        xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
                         offsetof(struct xfs_dsymlink_hdr, sl_crc));
}

const struct xfs_buf_ops xfs_symlink_buf_ops = {
        .verify_read = xfs_symlink_read_verify,
        .verify_write = xfs_symlink_write_verify,
};

void
xfs_symlink_local_to_remote(
        struct xfs_trans        *tp,
        struct xfs_buf          *bp,
        struct xfs_inode        *ip,
        struct xfs_ifork        *ifp)
{
        struct xfs_mount        *mp = ip->i_mount;
        char                    *buf;

        if (!xfs_sb_version_hascrc(&mp->m_sb)) {
                bp->b_ops = NULL;
                memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
                return;
        }

        /*
         * As this symlink fits in an inode literal area, it must also fit in
         * the smallest buffer the filesystem supports.
         */
        ASSERT(BBTOB(bp->b_length) >=
                        ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));

        bp->b_ops = &xfs_symlink_buf_ops;

        buf = bp->b_addr;
        buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
        memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
}