/*      $NetBSD: ext2fs_readwrite.c,v 1.79 2024/10/19 14:13:44 jakllsch Exp $   */

/*-
 * 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.
 */

/*-
 * Copyright (c) 1997 Manuel Bouyer.
 *
 * 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.
 *
 * 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.
 *
 *      @(#)ufs_readwrite.c     8.8 (Berkeley) 8/4/94
 * Modified for ext2fs by Manuel Bouyer.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ext2fs_readwrite.c,v 1.79 2024/10/19 14:13:44 jakllsch Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/resourcevar.h>
#include <sys/kernel.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/signalvar.h>
#include <sys/kauth.h>
#include <sys/bitops.h>

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

static int      ext2fs_post_read_update(struct vnode *, int, int);
static int      ext2fs_post_write_update(struct vnode *, struct uio *, int,
                    kauth_cred_t, off_t, int, int);

/*
 * Vnode op for reading.
 */
/* ARGSUSED */
int
ext2fs_read(void *v)
{
        struct vop_read_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int a_ioflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp;
        struct inode *ip;
        struct uio *uio;
        struct ufsmount *ump;
        vsize_t bytelen;
        int advice;
        int error;

        vp = ap->a_vp;
        ip = VTOI(vp);
        ump = ip->i_ump;
        uio = ap->a_uio;
        error = 0;

        KASSERT(uio->uio_rw == UIO_READ);
        KASSERT(vp->v_type == VREG || vp->v_type == VDIR);

        /* XXX Eliminate me by refusing directory reads from userland.  */
        if (vp->v_type == VDIR)
                return ext2fs_bufrd(vp, uio, ap->a_ioflag, ap->a_cred);

        if ((uint64_t)uio->uio_offset > ump->um_maxfilesize)
                return EFBIG;
        if (uio->uio_resid == 0)
                return 0;
        if (uio->uio_offset >= ext2fs_size(ip))
                goto out;

        KASSERT(vp->v_type == VREG);
        advice = IO_ADV_DECODE(ap->a_ioflag);
        while (uio->uio_resid > 0) {
                bytelen = MIN(ext2fs_size(ip) - uio->uio_offset,
                            uio->uio_resid);
                if (bytelen == 0)
                        break;

                error = ubc_uiomove(&vp->v_uobj, uio, bytelen, advice,
                    UBC_READ | UBC_PARTIALOK | UBC_VNODE_FLAGS(vp));
                if (error)
                        break;
        }

out:
        error = ext2fs_post_read_update(vp, ap->a_ioflag, error);
        return error;
}

/*
 * UFS op for reading via the buffer cache
 */
int
ext2fs_bufrd(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
{
        struct inode *ip;
        struct ufsmount *ump;
        struct m_ext2fs *fs;
        struct buf *bp;
        off_t bytesinfile;
        daddr_t lbn, nextlbn;
        long size, xfersize, blkoffset;
        int error;

        KASSERT(uio->uio_rw == UIO_READ);
        KASSERT(VOP_ISLOCKED(vp));
        KASSERT(vp->v_type == VDIR || vp->v_type == VLNK);

        ip = VTOI(vp);
        ump = ip->i_ump;
        fs = ip->i_e2fs;
        error = 0;

        KASSERT(vp->v_type != VLNK ||
            ext2fs_size(ip) >= ump->um_maxsymlinklen);
        KASSERT(vp->v_type != VLNK || ump->um_maxsymlinklen != 0 ||
            ext2fs_nblock(ip) != 0);

        if (uio->uio_offset > ump->um_maxfilesize)
                return EFBIG;
        if (uio->uio_resid == 0)
                return 0;
        if (uio->uio_offset >= ext2fs_size(ip))
                goto out;

        for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
                bytesinfile = ext2fs_size(ip) - uio->uio_offset;
                if (bytesinfile <= 0)
                        break;
                lbn = ext2_lblkno(fs, uio->uio_offset);
                nextlbn = lbn + 1;
                size = fs->e2fs_bsize;
                blkoffset = ext2_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 (ext2_lblktosize(fs, nextlbn) >= ext2fs_size(ip))
                        error = bread(vp, lbn, size, 0, &bp);
                else {
                        int nextsize = fs->e2fs_bsize;
                        error = breadn(vp, lbn,
                                size, &nextlbn, &nextsize, 1, 0, &bp);
                }
                if (error)
                        break;

                /*
                 * 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, 0);
        }
        if (bp != NULL)
                brelse(bp, 0);

out:
        error = ext2fs_post_read_update(vp, ioflag, error);
        return error;
}

static int
ext2fs_post_read_update(struct vnode *vp, int ioflag, int oerror)
{
        struct inode *ip = VTOI(vp);
        int error = oerror;

        if (!(vp->v_mount->mnt_flag & MNT_NOATIME)) {
                ip->i_flag |= IN_ACCESS;
                if ((ioflag & IO_SYNC) == IO_SYNC)
                        error = ext2fs_update(vp, NULL, NULL, UPDATE_WAIT);
        }

        /* Read error overrides any inode update error.  */
        if (oerror)
                error = oerror;
        return error;
}

/*
 * Vnode op for writing.
 */
int
ext2fs_write(void *v)
{
        struct vop_write_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int a_ioflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp;
        struct uio *uio;
        struct inode *ip;
        struct m_ext2fs *fs;
        struct ufsmount *ump;
        off_t osize;
        int blkoffset, error, ioflag, resid;
        vsize_t bytelen;
        off_t oldoff = 0;                                       /* XXX */
        bool async;
        int advice;
        const unsigned int fshift = ilog2(MAXPHYS);

        ioflag = ap->a_ioflag;
        advice = IO_ADV_DECODE(ioflag);
        uio = ap->a_uio;
        vp = ap->a_vp;
        ip = VTOI(vp);
        ump = ip->i_ump;
        error = 0;

        KASSERT(uio->uio_rw == UIO_WRITE);
        KASSERT(vp->v_type == 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;

        fs = ip->i_e2fs;
        if (uio->uio_offset < 0 ||
            (uint64_t)uio->uio_offset + uio->uio_resid > ump->um_maxfilesize)
                return EFBIG;
        if (uio->uio_resid == 0)
                return 0;

        async = vp->v_mount->mnt_flag & MNT_ASYNC;
        resid = uio->uio_resid;
        osize = ext2fs_size(ip);

        KASSERT(vp->v_type == VREG);
        while (uio->uio_resid > 0) {
                oldoff = uio->uio_offset;
                blkoffset = ext2_blkoff(fs, uio->uio_offset);
                bytelen = MIN(fs->e2fs_bsize - blkoffset, uio->uio_resid);

                if (vp->v_size < oldoff + bytelen) {
                        uvm_vnp_setwritesize(vp, oldoff + bytelen);
                }
                error = ufs_balloc_range(vp, uio->uio_offset, bytelen,
                    ap->a_cred, 0);
                if (error)
                        break;
                error = ubc_uiomove(&vp->v_uobj, uio, bytelen, advice,
                    UBC_WRITE | UBC_VNODE_FLAGS(vp));
                if (error)
                        break;

                /*
                 * update UVM's notion of the size now that we've
                 * copied the data into the vnode's pages.
                 */

                if (vp->v_size < uio->uio_offset) {
                        uvm_vnp_setsize(vp, uio->uio_offset);
                }

                /*
                 * flush what we just wrote if necessary.
                 * XXXUBC simplistic async flushing.
                 */

                if (!async && oldoff >> fshift != uio->uio_offset >> fshift) {
                        rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
                        error = VOP_PUTPAGES(vp, (oldoff >> fshift) << fshift,
                            (uio->uio_offset >> fshift) << fshift,
                            PGO_CLEANIT | PGO_LAZY);
                }
        }
        if (error == 0 && ioflag & IO_SYNC) {
                rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
                error = VOP_PUTPAGES(vp, trunc_page(oldoff),
                    round_page(ext2_blkroundup(fs, uio->uio_offset)),
                    PGO_CLEANIT | PGO_SYNCIO);
        }

        error = ext2fs_post_write_update(vp, uio, ioflag, ap->a_cred, osize,
            resid, error);
        return error;
}

/*
 * UFS op for writing via the buffer cache
 */
int
ext2fs_bufwr(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
{
        struct inode *ip;
        struct ufsmount *ump;
        struct m_ext2fs *fs;
        struct buf *bp;
        int flags;
        off_t osize;
        daddr_t lbn;
        int resid, blkoffset, xfersize;
        int error;

        KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
        KASSERT(vp->v_type == VDIR || vp->v_type == VLNK);
        KASSERT(vp->v_type != VDIR || ISSET(ioflag, IO_SYNC));
        KASSERT(uio->uio_rw == UIO_WRITE);

        ip = VTOI(vp);
        ump = ip->i_ump;
        fs = ip->i_e2fs;
        error = 0;

        if (uio->uio_offset < 0 ||
            uio->uio_resid > ump->um_maxfilesize ||
            uio->uio_offset > (ump->um_maxfilesize - uio->uio_resid))
                return EFBIG;
        if (uio->uio_resid == 0)
                return 0;

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

        for (error = 0; uio->uio_resid > 0;) {
                lbn = ext2_lblkno(fs, uio->uio_offset);
                blkoffset = ext2_blkoff(fs, uio->uio_offset);
                xfersize = MIN(fs->e2fs_bsize - blkoffset, uio->uio_resid);
                if (xfersize < fs->e2fs_bsize)
                        flags |= B_CLRBUF;
                else
                        flags &= ~B_CLRBUF;
                error = ext2fs_balloc(ip, lbn, blkoffset + xfersize, cred, &bp,
                    flags);
                if (error)
                        break;
                if (ext2fs_size(ip) < uio->uio_offset + xfersize) {
                        error = ext2fs_setsize(ip, uio->uio_offset + xfersize);
                        if (error)
                                break;
                }
                error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);

                /*
                 * update UVM's notion of the size now that we've
                 * copied the data into the vnode's pages.
                 */

                if (vp->v_size < uio->uio_offset) {
                        uvm_vnp_setsize(vp, uio->uio_offset);
                }

                if (ioflag & IO_SYNC)
                        (void)bwrite(bp);
                else if (xfersize + blkoffset == fs->e2fs_bsize)
                        bawrite(bp);
                else
                        bdwrite(bp);
                if (error || xfersize == 0)
                        break;
        }

        error = ext2fs_post_write_update(vp, uio, ioflag, cred, osize, resid,
            error);
        return error;
}

static int
ext2fs_post_write_update(struct vnode *vp, struct uio *uio, int ioflag,
    kauth_cred_t cred, off_t osize, int resid, int oerror)
{
        struct inode *ip = VTOI(vp);
        int error = oerror;

        /* Trigger ctime and mtime updates, and atime if MNT_RELATIME.  */
        ip->i_flag |= IN_CHANGE | IN_UPDATE;
        if (vp->v_mount->mnt_flag & MNT_RELATIME)
                ip->i_flag |= IN_ACCESS;

        /*
         * 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 && cred) {
                if (ip->i_e2fs_mode & ISUID) {
                        if (kauth_authorize_vnode(cred,
                            KAUTH_VNODE_RETAIN_SUID, vp, NULL, EPERM) != 0)
                                ip->i_e2fs_mode &= ISUID;
                }

                if (ip->i_e2fs_mode & ISGID) {
                        if (kauth_authorize_vnode(cred,
                            KAUTH_VNODE_RETAIN_SGID, vp, NULL, EPERM) != 0)
                                ip->i_e2fs_mode &= ~ISGID;
                }
        }

        /*
         * Update the size on disk: truncate back to original size on
         * error, or reflect the new size on success.
         */
        if (error) {
                (void) ext2fs_truncate(vp, osize, ioflag & IO_SYNC, cred);
                uio->uio_offset -= resid - uio->uio_resid;
                uio->uio_resid = resid;
        } else if (resid > uio->uio_resid && (ioflag & IO_SYNC) == IO_SYNC)
                error = ext2fs_update(vp, NULL, NULL, UPDATE_WAIT);

        /* Make sure the vnode uvm size matches the inode file size.  */
        KASSERT(vp->v_size == ext2fs_size(ip));

        /* Write error overrides any inode update error.  */
        if (oerror)
                error = oerror;
        return error;
}