/*      $OpenBSD: vfs_vnops.c,v 1.127 2026/04/08 12:08:25 jsg Exp $     */
/*      $NetBSD: vfs_vnops.c,v 1.20 1996/02/04 02:18:41 christos Exp $  */

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 *
 *      @(#)vfs_vnops.c 8.5 (Berkeley) 12/8/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/lock.h>
#include <sys/vnode.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/specdev.h>
#include <sys/unistd.h>

int vn_read(struct file *, struct uio *, int);
int vn_write(struct file *, struct uio *, int);
int vn_kqfilter(struct file *, struct knote *);
int vn_closefile(struct file *, struct proc *);
int vn_seek(struct file *, off_t *, int, struct proc *);

const struct fileops vnops = {
        .fo_read        = vn_read,
        .fo_write       = vn_write,
        .fo_ioctl       = vn_ioctl,
        .fo_kqfilter    = vn_kqfilter,
        .fo_stat        = vn_statfile,
        .fo_close       = vn_closefile,
        .fo_seek        = vn_seek,
};

/*
 * Common code for vnode open operations.
 * Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
 */
int
vn_open(struct nameidata *ndp, int fmode, int cmode)
{
        struct vnode *vp;
        struct proc *p = ndp->ni_cnd.cn_proc;
        struct ucred *cred = p->p_ucred;
        struct vattr va;
        struct cloneinfo *cip;
        int error;

        /*
         * The only valid flags to pass in here from NDINIT are
         * KERNELPATH or BYPASSUNVEIL. This function will override the
         * nameiop based on the fmode and cmode flags, so validate that
         * our caller has not set other flags or operations in the nameidata
         * structure.
         */
        KASSERT((ndp->ni_cnd.cn_flags & ~(KERNELPATH|BYPASSUNVEIL)) == 0);
        KASSERT(ndp->ni_cnd.cn_nameiop == 0);

        if ((fmode & (FREAD|FWRITE)) == 0)
                return (EINVAL);
        if ((fmode & (O_TRUNC | FWRITE)) == O_TRUNC)
                return (EINVAL);
        if ((fmode & (O_CREAT | O_DIRECTORY)) == (O_CREAT | O_DIRECTORY))
                return (EINVAL);
        if (fmode & O_CREAT) {
                ndp->ni_cnd.cn_nameiop = CREATE;
                ndp->ni_cnd.cn_flags |= LOCKPARENT | LOCKLEAF;
                if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
                        ndp->ni_cnd.cn_flags |= FOLLOW;
                if ((error = namei(ndp)) != 0)
                        return (error);

                if (ndp->ni_vp == NULL) {
                        vattr_null(&va);
                        va.va_type = VREG;
                        va.va_mode = cmode;
                        if (fmode & O_EXCL)
                                va.va_vaflags |= VA_EXCLUSIVE;
                        error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
                                           &ndp->ni_cnd, &va);
                        vput(ndp->ni_dvp);
                        if (error)
                                return (error);
                        fmode &= ~O_TRUNC;
                        vp = ndp->ni_vp;
                } else {
                        VOP_ABORTOP(ndp->ni_dvp, &ndp->ni_cnd);
                        if (ndp->ni_dvp == ndp->ni_vp)
                                vrele(ndp->ni_dvp);
                        else
                                vput(ndp->ni_dvp);
                        ndp->ni_dvp = NULL;
                        vp = ndp->ni_vp;
                        if (fmode & O_EXCL) {
                                error = EEXIST;
                                goto bad;
                        }
                        if (vp->v_type == VDIR) {
                                error = EISDIR;
                                goto bad;
                        }
                        fmode &= ~O_CREAT;
                }
        } else {
                ndp->ni_cnd.cn_nameiop = LOOKUP;
                ndp->ni_cnd.cn_flags |= ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
                if ((error = namei(ndp)) != 0)
                        return (error);
                vp = ndp->ni_vp;
        }
        if (vp->v_type == VSOCK) {
                error = EOPNOTSUPP;
                goto bad;
        }
        if (vp->v_type == VLNK) {
                error = ELOOP;
                goto bad;
        }
        if ((fmode & O_DIRECTORY) && vp->v_type != VDIR) {
                error = ENOTDIR;
                goto bad;
        }
        if ((fmode & O_CREAT) == 0) {
                if (fmode & FREAD) {
                        if ((error = VOP_ACCESS(vp, VREAD, cred, p)) != 0)
                                goto bad;
                }
                if (fmode & FWRITE) {
                        if (vp->v_type == VDIR) {
                                error = EISDIR;
                                goto bad;
                        }
                        if ((error = vn_writechk(vp)) != 0 ||
                            (error = VOP_ACCESS(vp, VWRITE, cred, p)) != 0)
                                goto bad;
                }
        }
        if ((fmode & O_TRUNC) && vp->v_type == VREG) {
                vattr_null(&va);
                va.va_size = 0;
                if ((error = VOP_SETATTR(vp, &va, cred, p)) != 0)
                        goto bad;
        }
        if ((error = VOP_OPEN(vp, fmode, cred, p)) != 0)
                goto bad;

        if (vp->v_flag & VCLONED) {
                cip = (struct cloneinfo *)vp->v_data;

                vp->v_flag &= ~VCLONED;

                ndp->ni_vp = cip->ci_vp;        /* return cloned vnode */
                vp->v_data = cip->ci_data;      /* restore v_data */
                VOP_UNLOCK(vp);                 /* keep a reference */
                vp = ndp->ni_vp;                /* for the increment below */

                free(cip, M_TEMP, sizeof(*cip));
        }

        if (fmode & FWRITE)
                vp->v_writecount++;
        return (0);
bad:
        vput(vp);
        return (error);
}

/*
 * Check for write permissions on the specified vnode.
 * Prototype text segments cannot be written.
 */
int
vn_writechk(struct vnode *vp)
{
        /*
         * Disallow write attempts on read-only file systems;
         * unless the file is a socket or a block or character
         * device resident on the file system.
         */
        if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_RDONLY)) {
                switch (vp->v_type) {
                case VREG:
                case VDIR:
                case VLNK:
                        return (EROFS);
                case VNON:
                case VCHR:
                case VSOCK:
                case VFIFO:
                case VBAD:
                case VBLK:
                        break;
                }
        }
        /*
         * If there's shared text associated with
         * the vnode, try to free it up once.  If
         * we fail, we can't allow writing.
         */
        if ((vp->v_flag & VTEXT) && !uvm_vnp_uncache(vp))
                return (ETXTBSY);

        return (0);
}

/*
 * Check whether a write operation would exceed the file size rlimit
 * for the process, if one should be applied for this operation.
 * If a partial write should take place, the uio is adjusted and the
 * amount by which the request would have exceeded the limit is returned
 * via the 'overrun' argument.
 */
int
vn_fsizechk(struct vnode *vp, struct uio *uio, int ioflag, ssize_t *overrun)
{
        struct proc *p = uio->uio_procp;

        *overrun = 0;
        if (vp->v_type == VREG && p != NULL && !(ioflag & IO_NOLIMIT)) {
                rlim_t limit = lim_cur_proc(p, RLIMIT_FSIZE);

                /* if already at or over the limit, send the signal and fail */
                if (uio->uio_offset >= limit) {
                        psignal(p, SIGXFSZ);
                        return (EFBIG);
                }

                /* otherwise, clamp the write to stay under the limit */
                if (uio->uio_resid > limit - uio->uio_offset) {
                        *overrun = uio->uio_resid - (limit - uio->uio_offset);
                        uio->uio_resid = limit - uio->uio_offset;
                }
        }

        return (0);
}


/*
 * Mark a vnode as being the text image of a running process.
 */
void
vn_marktext(struct vnode *vp)
{
        vp->v_flag |= VTEXT;
}

/*
 * Vnode close call
 */
int
vn_close(struct vnode *vp, int flags, struct ucred *cred, struct proc *p)
{
        int error;

        if (flags & FWRITE)
                vp->v_writecount--;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        error = VOP_CLOSE(vp, flags, cred, p);
        vput(vp);
        return (error);
}

/*
 * Package up an I/O request on a vnode into a uio and do it.
 */
int
vn_rdwr(enum uio_rw rw, struct vnode *vp, caddr_t base, int len, off_t offset,
    enum uio_seg segflg, int ioflg, struct ucred *cred, size_t *aresid,
    struct proc *p)
{
        struct uio auio;
        struct iovec aiov;
        int error;

        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        aiov.iov_base = base;
        aiov.iov_len = len;
        auio.uio_resid = len;
        auio.uio_offset = offset;
        auio.uio_segflg = segflg;
        auio.uio_rw = rw;
        auio.uio_procp = p;

        if ((ioflg & IO_NODELOCKED) == 0)
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if (rw == UIO_READ) {
                error = VOP_READ(vp, &auio, ioflg, cred);
        } else {
                error = VOP_WRITE(vp, &auio, ioflg, cred);
        }
        if ((ioflg & IO_NODELOCKED) == 0)
                VOP_UNLOCK(vp);

        if (aresid)
                *aresid = auio.uio_resid;
        else
                if (auio.uio_resid && error == 0)
                        error = EIO;
        return (error);
}

/*
 * File table vnode read routine.
 */
int
vn_read(struct file *fp, struct uio *uio, int fflags)
{
        struct vnode *vp = fp->f_data;
        struct ucred *cred = fp->f_cred;
        size_t count = uio->uio_resid;
        off_t offset;
        int error;

        KERNEL_LOCK();

        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);

        if ((fflags & FO_POSITION) == 0)
                offset = uio->uio_offset = fp->f_offset;
        else
                offset = uio->uio_offset;

        /* no wrap around of offsets except on character devices */
        if (vp->v_type != VCHR && count > LLONG_MAX - offset) {
                error = EINVAL;
                goto done;
        }

        if (vp->v_type == VDIR) {
                error = EISDIR;
                goto done;
        }

        error = VOP_READ(vp, uio, (fp->f_flag & FNONBLOCK) ? IO_NDELAY : 0,
            cred);
        if ((fflags & FO_POSITION) == 0) {
                mtx_enter(&fp->f_mtx);
                fp->f_offset += count - uio->uio_resid;
                mtx_leave(&fp->f_mtx);
        }
done:
        VOP_UNLOCK(vp);
        KERNEL_UNLOCK();
        return (error);
}

/*
 * File table vnode write routine.
 */
int
vn_write(struct file *fp, struct uio *uio, int fflags)
{
        struct vnode *vp = fp->f_data;
        struct ucred *cred = fp->f_cred;
        int error, ioflag = IO_UNIT;
        size_t count;

        KERNEL_LOCK();

        /* note: pwrite/pwritev are unaffected by O_APPEND */
        if (vp->v_type == VREG && (fp->f_flag & O_APPEND) &&
            (fflags & FO_POSITION) == 0)
                ioflag |= IO_APPEND;
        if (fp->f_flag & FNONBLOCK)
                ioflag |= IO_NDELAY;
        if ((fp->f_flag & FFSYNC) ||
            (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
                ioflag |= IO_SYNC;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if ((fflags & FO_POSITION) == 0)
                uio->uio_offset = fp->f_offset;
        count = uio->uio_resid;
        error = VOP_WRITE(vp, uio, ioflag, cred);
        if ((fflags & FO_POSITION) == 0) {
                mtx_enter(&fp->f_mtx);
                if (ioflag & IO_APPEND)
                        fp->f_offset = uio->uio_offset;
                else
                        fp->f_offset += count - uio->uio_resid;
                mtx_leave(&fp->f_mtx);
        }
        VOP_UNLOCK(vp);

        KERNEL_UNLOCK();
        return (error);
}

/*
 * File table wrapper for vn_stat
 */
int
vn_statfile(struct file *fp, struct stat *sb, struct proc *p)
{
        struct vnode *vp = fp->f_data;
        int error;

        KERNEL_LOCK();
        error = vn_stat(vp, sb, p);
        KERNEL_UNLOCK();

        return (error);
}

/*
 * vnode stat routine.
 */
int
vn_stat(struct vnode *vp, struct stat *sb, struct proc *p)
{
        struct vattr va;
        int error;
        mode_t mode;

        error = VOP_GETATTR(vp, &va, p->p_ucred, p);
        if (error)
                return (error);
        /*
         * Copy from vattr table
         */
        memset(sb, 0, sizeof(*sb));
        sb->st_dev = va.va_fsid;
        sb->st_ino = va.va_fileid;
        mode = va.va_mode;
        switch (vp->v_type) {
        case VREG:
                mode |= S_IFREG;
                break;
        case VDIR:
                mode |= S_IFDIR;
                break;
        case VBLK:
                mode |= S_IFBLK;
                break;
        case VCHR:
                mode |= S_IFCHR;
                break;
        case VLNK:
                mode |= S_IFLNK;
                break;
        case VSOCK:
                mode |= S_IFSOCK;
                break;
        case VFIFO:
                mode |= S_IFIFO;
                break;
        default:
                return (EBADF);
        }
        sb->st_mode = mode;
        sb->st_nlink = va.va_nlink;
        sb->st_uid = va.va_uid;
        sb->st_gid = va.va_gid;
        sb->st_rdev = va.va_rdev;
        sb->st_size = va.va_size;
        sb->st_atim.tv_sec  = va.va_atime.tv_sec;
        sb->st_atim.tv_nsec = va.va_atime.tv_nsec;
        sb->st_mtim.tv_sec  = va.va_mtime.tv_sec;
        sb->st_mtim.tv_nsec = va.va_mtime.tv_nsec;
        sb->st_ctim.tv_sec  = va.va_ctime.tv_sec;
        sb->st_ctim.tv_nsec = va.va_ctime.tv_nsec;
        sb->st_blksize = va.va_blocksize;
        sb->st_flags = va.va_flags;
        sb->st_gen = va.va_gen;
        sb->st_blocks = va.va_bytes / S_BLKSIZE;
        return (0);
}

/*
 * File table vnode ioctl routine.
 */
int
vn_ioctl(struct file *fp, u_long com, caddr_t data, struct proc *p)
{
        struct vnode *vp = fp->f_data;
        struct vattr vattr;
        int error = ENOTTY;

        KERNEL_LOCK();
        switch (vp->v_type) {

        case VREG:
        case VDIR:
                if (com == FIONREAD) {
                        error = VOP_GETATTR(vp, &vattr, p->p_ucred, p);
                        if (error)
                                break;
                        *(int *)data = vattr.va_size - foffset(fp);

                } else if (com == FIOASYNC)                     /* XXX */
                        error = 0;                              /* XXX */
                break;

        case VFIFO:
        case VCHR:
        case VBLK:
                error = VOP_IOCTL(vp, com, data, fp->f_flag, p->p_ucred, p);
                if (error == 0 && com == TIOCSCTTY) {
                        struct session *s = p->p_p->ps_session;
                        struct vnode *ovp = s->s_ttyvp;
                        s->s_ttyvp = vp;
                        vref(vp);
                        if (ovp)
                                vrele(ovp);
                }
                break;

        default:
                break;
        }
        KERNEL_UNLOCK();

        return (error);
}

/*
 * Check that the vnode is still valid, and if so
 * acquire requested lock.
 */
int
vn_lock(struct vnode *vp, int flags)
{
        int error, xlocked, do_wakeup;

        do {
                mtx_enter(&vnode_mtx);
                if (vp->v_lflag & VXLOCK) {
                        vp->v_lflag |= VXWANT;
                        msleep_nsec(vp, &vnode_mtx, PINOD, "vn_lock", INFSLP);
                        mtx_leave(&vnode_mtx);
                        error = ENOENT;
                } else {
                        vp->v_lockcount++;
                        mtx_leave(&vnode_mtx);

                        error = VOP_LOCK(vp, flags);

                        mtx_enter(&vnode_mtx);
                        vp->v_lockcount--;
                        do_wakeup = (vp->v_lockcount == 0);
                        xlocked = vp->v_lflag & VXLOCK;
                        mtx_leave(&vnode_mtx);

                        if (error == 0) {
                                if (!xlocked)
                                        return (0);

                                /*
                                 * The vnode was exclusively locked while
                                 * acquiring the requested lock. Release it and
                                 * try again.
                                 */
                                error = ENOENT;
                                VOP_UNLOCK(vp);
                                if (do_wakeup)
                                        wakeup_one(&vp->v_lockcount);
                        }
                }
        } while (flags & LK_RETRY);
        return (error);
}

/*
 * File table vnode close routine.
 */
int
vn_closefile(struct file *fp, struct proc *p)
{
        struct vnode *vp = fp->f_data;
        struct flock lf;
        int error;

        KERNEL_LOCK();
        if ((fp->f_iflags & FIF_HASLOCK)) {
                lf.l_whence = SEEK_SET;
                lf.l_start = 0;
                lf.l_len = 0;
                lf.l_type = F_UNLCK;
                (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK);
        }
        error = vn_close(vp, fp->f_flag, fp->f_cred, p);
        KERNEL_UNLOCK();
        return (error);
}

int
vn_kqfilter(struct file *fp, struct knote *kn)
{
        int error;

        KERNEL_LOCK();
        error = VOP_KQFILTER(fp->f_data, fp->f_flag, kn);
        KERNEL_UNLOCK();
        return (error);
}

int
vn_seek(struct file *fp, off_t *offset, int whence, struct proc *p)
{
        struct ucred *cred = p->p_ucred;
        struct vnode *vp = fp->f_data;
        struct vattr vattr;
        off_t newoff;
        int error = 0;
        int special;

        if (vp->v_type == VFIFO)
                return (ESPIPE);

        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);

        if (vp->v_type == VCHR)
                special = 1;
        else
                special = 0;

        switch (whence) {
        case SEEK_CUR:
                newoff = fp->f_offset + *offset;
                break;
        case SEEK_END:
                KERNEL_LOCK();
                error = VOP_GETATTR(vp, &vattr, cred, p);
                KERNEL_UNLOCK();
                if (error)
                        goto out;
                newoff = *offset + (off_t)vattr.va_size;
                break;
        case SEEK_SET:
                newoff = *offset;
                break;
        default:
                error = EINVAL;
                goto out;
        }
        if (!special && newoff < 0) {
                error = EINVAL;
                goto out;
        }
        mtx_enter(&fp->f_mtx);
        fp->f_offset = newoff;
        mtx_leave(&fp->f_mtx);
        *offset = newoff;

out:
        VOP_UNLOCK(vp);
        return (error);
}

/*
 * Common code for vnode access operations.
 */

/* Check if a directory can be found inside another in the hierarchy */
int
vn_isunder(struct vnode *lvp, struct vnode *rvp, struct proc *p)
{
        int error;

        error = vfs_getcwd_common(lvp, rvp, NULL, NULL, MAXPATHLEN/2, 0, p);

        if (!error)
                return (1);

        return (0);
}