/*      $OpenBSD: ext2fs_readwrite.c,v 1.46 2023/03/08 04:43:09 guenther Exp $  */
/*      $NetBSD: ext2fs_readwrite.c,v 1.16 2001/02/27 04:37:47 chs Exp $        */

/*-
 * Copyright (c) 1997 Manuel Bouyer.
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 *
 *      @(#)ufs_readwrite.c     8.8 (Berkeley) 8/4/94
 * Modified for ext2fs by Manuel Bouyer.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/resourcevar.h>
#include <sys/kernel.h>
#include <sys/stat.h>
#include <sys/buf.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/signalvar.h>
#include <sys/event.h>

#include <ufs/ufs/quota.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/inode.h>
#include <ufs/ext2fs/ext2fs.h>
#include <ufs/ext2fs/ext2fs_extern.h>


static int      ext2_ind_read(struct vnode *, struct inode *, struct m_ext2fs *, struct uio *);
static int      ext4_ext_read(struct vnode *, struct inode *, struct m_ext2fs *, struct uio *);

/*
 * Vnode op for reading.
 */
int
ext2fs_read(void *v)
{
        struct vop_read_args *ap = v;
        struct vnode *vp;
        struct inode *ip;
        struct uio *uio;
        struct m_ext2fs *fs;

        vp = ap->a_vp;
        ip = VTOI(vp);
        uio = ap->a_uio;
        fs = ip->i_e2fs;

        if (ip->i_e2fs_flags & EXT4_EXTENTS)
                return ext4_ext_read(vp, ip, fs, uio);
        else
                return ext2_ind_read(vp, ip, fs, uio);
}

static int
ext2_ind_read(struct vnode *vp, struct inode *ip, struct m_ext2fs *fs,
    struct uio *uio)
{
        struct buf *bp;
        daddr_t lbn, nextlbn;
        off_t bytesinfile;
        int size, xfersize, blkoffset;
        int error;

#ifdef DIAGNOSTIC
        if (uio->uio_rw != UIO_READ)
                panic("%s: mode", "ext2fs_read");

        if (vp->v_type == VLNK) {
                if (ext2fs_size(ip) < EXT2_MAXSYMLINKLEN)
                        panic("%s: short symlink", "ext2fs_read");
        } else if (vp->v_type != VREG && vp->v_type != VDIR)
                panic("%s: type %d", "ext2fs_read", vp->v_type);
#endif
        if (uio->uio_offset < 0)
                return (EINVAL);
        if (uio->uio_resid == 0)
                return (0);

        for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
                if ((bytesinfile = ext2fs_size(ip) - uio->uio_offset) <= 0)
                        break;
                lbn = lblkno(fs, uio->uio_offset);
                nextlbn = lbn + 1;
                size = fs->e2fs_bsize;
                blkoffset = blkoff(fs, uio->uio_offset);
                xfersize = fs->e2fs_bsize - blkoffset;
                if (uio->uio_resid < xfersize)
                        xfersize = uio->uio_resid;
                if (bytesinfile < xfersize)
                        xfersize = bytesinfile;

                if (lblktosize(fs, nextlbn) >= ext2fs_size(ip))
                        error = bread(vp, lbn, size, &bp);
                else if (lbn - 1 == ip->i_ci.ci_lastr) {
                        int nextsize = fs->e2fs_bsize;
                        error = breadn(vp, lbn, size, &nextlbn, &nextsize,
                            1, &bp);
                } else
                        error = bread(vp, lbn, size, &bp);
                if (error)
                        break;
                ip->i_ci.ci_lastr = lbn;

                /*
                 * We should only get non-zero b_resid when an I/O error
                 * has occurred, which should cause us to break above.
                 * However, if the short read did not cause an error,
                 * then we want to ensure that we do not uiomove bad
                 * or uninitialized data.
                 */
                size -= bp->b_resid;
                if (size < xfersize) {
                        if (size == 0)
                                break;
                        xfersize = size;
                }
                error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);
                if (error)
                        break;
                brelse(bp);
        }
        if (bp != NULL)
                brelse(bp);

        if (!(vp->v_mount->mnt_flag & MNT_NOATIME)) {
                ip->i_flag |= IN_ACCESS;
        }
        return (error);
}

int
ext4_ext_read(struct vnode *vp, struct inode *ip, struct m_ext2fs *fs, struct uio *uio)
{
        struct ext4_extent_path path;
        struct ext4_extent nex, *ep;
        struct buf *bp;
        daddr_t lbn, pos;
        off_t bytesinfile;
        int size, xfersize, blkoffset;
        int error, cache_type;

        memset(&path, 0, sizeof path);

        if (uio->uio_offset < 0)
                return (EINVAL);
        if (uio->uio_resid == 0)
                return (0);

        while (uio->uio_resid > 0) {
                if ((bytesinfile = ext2fs_size(ip) - uio->uio_offset) <= 0)
                        break;
                lbn = lblkno(fs, uio->uio_offset);
                size = fs->e2fs_bsize;
                blkoffset = blkoff(fs, uio->uio_offset);

                xfersize = fs->e2fs_fsize - blkoffset;
                xfersize = MIN(xfersize, uio->uio_resid);
                xfersize = MIN(xfersize, bytesinfile);

                cache_type = ext4_ext_in_cache(ip, lbn, &nex);
                switch (cache_type) {
                case EXT4_EXT_CACHE_NO:
                        ext4_ext_find_extent(fs, ip, lbn, &path);
                        if ((ep = path.ep_ext) == NULL)
                                return (EIO);
                        ext4_ext_put_cache(ip, ep, EXT4_EXT_CACHE_IN);

                        pos = lbn - ep->e_blk + (((daddr_t) ep->e_start_hi << 32) | ep->e_start_lo);
                        if (path.ep_bp != NULL) {
                                brelse(path.ep_bp);
                                path.ep_bp = NULL;
                        }
                        break;
                case EXT4_EXT_CACHE_GAP:
                        /* block has not been allocated yet */
                        return (0);
                case EXT4_EXT_CACHE_IN:
                        pos = lbn - nex.e_blk + (((daddr_t) nex.e_start_hi << 32) | nex.e_start_lo);
                        break;
                }
                error = bread(ip->i_devvp, fsbtodb(fs, pos), size, &bp);
                if (error) {
                        brelse(bp);
                        return (error);
                }
                size -= bp->b_resid;
                if (size < xfersize) {
                        if (size == 0) {
                                brelse(bp);
                                break;
                        }
                        xfersize = size;
                }
                error = uiomove(bp->b_data + blkoffset, xfersize, uio);
                brelse(bp);
                if (error)
                        return (error);
        }
        return (0);
}

/*
 * Vnode op for writing.
 */
int
ext2fs_write(void *v)
{
        struct vop_write_args *ap = v;
        struct vnode *vp;
        struct uio *uio;
        struct inode *ip;
        struct m_ext2fs *fs;
        struct buf *bp;
        int32_t lbn;
        off_t osize;
        int blkoffset, error, extended, flags, ioflag, size, xfersize;
        size_t resid;
        ssize_t overrun;

        extended = 0;
        ioflag = ap->a_ioflag;
        uio = ap->a_uio;
        vp = ap->a_vp;
        ip = VTOI(vp);

#ifdef DIAGNOSTIC
        if (uio->uio_rw != UIO_WRITE)
                panic("%s: mode", "ext2fs_write");
#endif

        /*
         * If writing 0 bytes, succeed and do not change
         * update time or file offset (standards compliance)
         */
        if (uio->uio_resid == 0)
                return (0);

        switch (vp->v_type) {
        case VREG:
                if (ioflag & IO_APPEND)
                        uio->uio_offset = ext2fs_size(ip);
                if ((ip->i_e2fs_flags & EXT2_APPEND) &&
                        uio->uio_offset != ext2fs_size(ip))
                        return (EPERM);
                /* FALLTHROUGH */
        case VLNK:
                break;
        case VDIR:
                if ((ioflag & IO_SYNC) == 0)
                        panic("%s: nonsync dir write", "ext2fs_write");
                break;
        default:
                panic("%s: type", "ext2fs_write");
        }

        fs = ip->i_e2fs;
        if (e2fs_overflow(fs, uio->uio_resid, uio->uio_offset + uio->uio_resid))
                return (EFBIG);

        /* do the filesize rlimit check */
        if ((error = vn_fsizechk(vp, uio, ioflag, &overrun)))
                return (error);

        resid = uio->uio_resid;
        osize = ext2fs_size(ip);
        flags = ioflag & IO_SYNC ? B_SYNC : 0;

        for (error = 0; uio->uio_resid > 0;) {
                lbn = lblkno(fs, uio->uio_offset);
                blkoffset = blkoff(fs, uio->uio_offset);
                xfersize = fs->e2fs_bsize - blkoffset;
                if (uio->uio_resid < xfersize)
                        xfersize = uio->uio_resid;
                if (fs->e2fs_bsize > xfersize)
                        flags |= B_CLRBUF;
                else
                        flags &= ~B_CLRBUF;

                error = ext2fs_buf_alloc(ip,
                        lbn, blkoffset + xfersize, ap->a_cred, &bp, flags);
                if (error)
                        break;
                if (uio->uio_offset + xfersize > ext2fs_size(ip)) {
                        error = ext2fs_setsize(ip, uio->uio_offset + xfersize);
                        if (error)
                                break;
                        uvm_vnp_setsize(vp, ext2fs_size(ip));
                        extended = 1;
                }
                uvm_vnp_uncache(vp);

                size = fs->e2fs_bsize - bp->b_resid;
                if (size < xfersize)
                        xfersize = size;

                error = uiomove(bp->b_data + blkoffset, xfersize, uio);
                /*
                 * If the buffer is not already filled and we encounter an
                 * error while trying to fill it, we have to clear out any
                 * garbage data from the pages instantiated for the buffer.
                 * If we do not, a failed uiomove() during a write can leave
                 * the prior contents of the pages exposed to a userland mmap.
                 *
                 * Note that we don't need to clear buffers that were
                 * allocated with the B_CLRBUF flag set.
                 */
                if (error != 0 && !(flags & B_CLRBUF))
                        memset(bp->b_data + blkoffset, 0, xfersize);

                if (ioflag & IO_NOCACHE)
                        bp->b_flags |= B_NOCACHE;

                if (ioflag & IO_SYNC)
                        (void)bwrite(bp);
                else if (xfersize + blkoffset == fs->e2fs_bsize)
                        bawrite(bp);
                else
                        bdwrite(bp);
                if (error || xfersize == 0)
                        break;
                ip->i_flag |= IN_CHANGE | IN_UPDATE;
        }
        /*
         * If we successfully wrote any data, and we are not the superuser
         * we clear the setuid and setgid bits as a precaution against
         * tampering.
         */
        if (resid > uio->uio_resid && ap->a_cred && ap->a_cred->cr_uid != 0)
                ip->i_e2fs_mode &= ~(ISUID | ISGID);
        if (resid > uio->uio_resid)
                VN_KNOTE(vp, NOTE_WRITE | (extended ? NOTE_EXTEND : 0));
        if (error) {
                if (ioflag & IO_UNIT) {
                        (void)ext2fs_truncate(ip, osize,
                                ioflag & IO_SYNC, ap->a_cred);
                        uio->uio_offset -= resid - uio->uio_resid;
                        uio->uio_resid = resid;
                }
        } else if (resid > uio->uio_resid && (ioflag & IO_SYNC)) {
                error = ext2fs_update(ip, 1);
        }
        /* correct the result for writes clamped by vn_fsizechk() */
        uio->uio_resid += overrun;
        return (error);
}