/
vfs_vnops.c
1674 lines (1485 loc) · 38.4 KB
/
vfs_vnops.c
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/* $NetBSD: vfs_vnops.c,v 1.242 2023/07/10 02:31:55 christos Exp $ */
/*-
* Copyright (c) 2009 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Andrew Doran.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* 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 8.14 (Berkeley) 6/15/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_vnops.c,v 1.242 2023/07/10 02:31:55 christos Exp $");
#include "veriexec.h"
#include <sys/param.h>
#include <sys/systm.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/namei.h>
#include <sys/vnode_impl.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/poll.h>
#include <sys/kauth.h>
#include <sys/syslog.h>
#include <sys/fstrans.h>
#include <sys/atomic.h>
#include <sys/filedesc.h>
#include <sys/wapbl.h>
#include <sys/mman.h>
#include <miscfs/specfs/specdev.h>
#include <miscfs/fifofs/fifo.h>
#include <uvm/uvm_extern.h>
#include <uvm/uvm_readahead.h>
#include <uvm/uvm_device.h>
#ifdef UNION
#include <fs/union/union.h>
#endif
#ifndef COMPAT_ZERODEV
#define COMPAT_ZERODEV(dev) (0)
#endif
int (*vn_union_readdir_hook)(struct vnode **, struct file *, struct lwp *);
#include <sys/verified_exec.h>
static int vn_read(file_t *fp, off_t *offset, struct uio *uio,
kauth_cred_t cred, int flags);
static int vn_write(file_t *fp, off_t *offset, struct uio *uio,
kauth_cred_t cred, int flags);
static int vn_closefile(file_t *fp);
static int vn_poll(file_t *fp, int events);
static int vn_fcntl(file_t *fp, u_int com, void *data);
static int vn_statfile(file_t *fp, struct stat *sb);
static int vn_ioctl(file_t *fp, u_long com, void *data);
static int vn_mmap(struct file *, off_t *, size_t, int, int *, int *,
struct uvm_object **, int *);
static int vn_seek(struct file *, off_t, int, off_t *, int);
static int vn_advlock(struct file *, void *, int, struct flock *, int);
static int vn_fpathconf(struct file *, int, register_t *);
static int vn_posix_fadvise(struct file *, off_t, off_t, int);
static int vn_truncate(file_t *, off_t);
const struct fileops vnops = {
.fo_name = "vn",
.fo_read = vn_read,
.fo_write = vn_write,
.fo_ioctl = vn_ioctl,
.fo_fcntl = vn_fcntl,
.fo_poll = vn_poll,
.fo_stat = vn_statfile,
.fo_close = vn_closefile,
.fo_kqfilter = vn_kqfilter,
.fo_restart = fnullop_restart,
.fo_mmap = vn_mmap,
.fo_seek = vn_seek,
.fo_advlock = vn_advlock,
.fo_fpathconf = vn_fpathconf,
.fo_posix_fadvise = vn_posix_fadvise,
.fo_truncate = vn_truncate,
};
/*
* Common code for vnode open operations.
* Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
*
* at_dvp is the directory for openat(), if any.
* pb is the path.
* nmode is additional namei flags, restricted to TRYEMULROOT and NOCHROOT.
* fmode is the open flags, converted from O_* to F*
* cmode is the creation file permissions.
*
* XXX shouldn't cmode be mode_t?
*
* On success produces either a locked vnode in *ret_vp, or NULL in
* *ret_vp and a file descriptor number in *ret_fd.
*
* The caller may pass NULL for ret_fd (and ret_domove), in which case
* EOPNOTSUPP will be produced in the cases that would otherwise return
* a file descriptor.
*
* Note that callers that want no-follow behavior should pass
* O_NOFOLLOW in fmode. Neither FOLLOW nor NOFOLLOW in nmode is
* honored.
*/
int
vn_open(struct vnode *at_dvp, struct pathbuf *pb,
int nmode, int fmode, int cmode,
struct vnode **ret_vp, bool *ret_domove, int *ret_fd)
{
struct nameidata nd;
struct vnode *vp = NULL;
struct lwp *l = curlwp;
kauth_cred_t cred = l->l_cred;
struct vattr va;
int error;
const char *pathstring;
KASSERT((nmode & (TRYEMULROOT | NOCHROOT)) == nmode);
KASSERT(ret_vp != NULL);
KASSERT((ret_domove == NULL) == (ret_fd == NULL));
if ((fmode & (O_CREAT | O_DIRECTORY)) == (O_CREAT | O_DIRECTORY))
return EINVAL;
NDINIT(&nd, LOOKUP, nmode, pb);
if (at_dvp != NULL)
NDAT(&nd, at_dvp);
nd.ni_cnd.cn_flags &= TRYEMULROOT | NOCHROOT;
if (fmode & O_CREAT) {
nd.ni_cnd.cn_nameiop = CREATE;
nd.ni_cnd.cn_flags |= LOCKPARENT | LOCKLEAF;
if ((fmode & O_EXCL) == 0 &&
((fmode & O_NOFOLLOW) == 0))
nd.ni_cnd.cn_flags |= FOLLOW;
if ((fmode & O_EXCL) == 0)
nd.ni_cnd.cn_flags |= NONEXCLHACK;
} else {
nd.ni_cnd.cn_nameiop = LOOKUP;
nd.ni_cnd.cn_flags |= LOCKLEAF;
if ((fmode & O_NOFOLLOW) == 0)
nd.ni_cnd.cn_flags |= FOLLOW;
}
pathstring = pathbuf_stringcopy_get(nd.ni_pathbuf);
if (pathstring == NULL) {
return ENOMEM;
}
/*
* When this "interface" was exposed to do_open() it used
* to initialize l_dupfd to -newfd-1 (thus passing in the
* new file handle number to use)... but nothing in the
* kernel uses that value. So just send 0.
*/
l->l_dupfd = 0;
error = namei(&nd);
if (error)
goto out;
vp = nd.ni_vp;
#if NVERIEXEC > 0
error = veriexec_openchk(l, nd.ni_vp, pathstring, fmode);
if (error) {
/* We have to release the locks ourselves */
/*
* 20210604 dholland passing NONEXCLHACK means we can
* get ni_dvp == NULL back if ni_vp exists, and we should
* treat that like the non-O_CREAT case.
*/
if ((fmode & O_CREAT) != 0 && nd.ni_dvp != NULL) {
if (vp == NULL) {
vput(nd.ni_dvp);
} else {
VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
if (nd.ni_dvp == nd.ni_vp)
vrele(nd.ni_dvp);
else
vput(nd.ni_dvp);
nd.ni_dvp = NULL;
vput(vp);
vp = NULL;
}
} else {
vput(vp);
vp = NULL;
}
goto out;
}
#endif /* NVERIEXEC > 0 */
/*
* 20210604 dholland ditto
*/
if ((fmode & O_CREAT) != 0 && nd.ni_dvp != NULL) {
if (nd.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(nd.ni_dvp, &nd.ni_vp,
&nd.ni_cnd, &va);
if (error) {
vput(nd.ni_dvp);
goto out;
}
fmode &= ~O_TRUNC;
vp = nd.ni_vp;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vput(nd.ni_dvp);
} else {
VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
if (nd.ni_dvp == nd.ni_vp)
vrele(nd.ni_dvp);
else
vput(nd.ni_dvp);
nd.ni_dvp = NULL;
vp = nd.ni_vp;
if (fmode & O_EXCL) {
error = EEXIST;
goto bad;
}
fmode &= ~O_CREAT;
}
} else if ((fmode & O_CREAT) != 0) {
/*
* 20210606 dholland passing NONEXCLHACK means this
* case exists; it is the same as the following one
* but also needs to do things in the second (exists)
* half of the following block. (Besides handle
* ni_dvp, anyway.)
*/
vp = nd.ni_vp;
KASSERT((fmode & O_EXCL) == 0);
fmode &= ~O_CREAT;
} else {
vp = nd.ni_vp;
}
if (vp->v_type == VSOCK) {
error = EOPNOTSUPP;
goto bad;
}
if (nd.ni_vp->v_type == VLNK) {
error = EFTYPE;
goto bad;
}
if ((fmode & O_CREAT) == 0) {
error = vn_openchk(vp, cred, fmode);
if (error != 0)
goto bad;
}
if (fmode & O_TRUNC) {
vattr_null(&va);
va.va_size = 0;
error = VOP_SETATTR(vp, &va, cred);
if (error != 0)
goto bad;
}
if ((error = VOP_OPEN(vp, fmode, cred)) != 0)
goto bad;
if (fmode & FWRITE) {
mutex_enter(vp->v_interlock);
vp->v_writecount++;
mutex_exit(vp->v_interlock);
}
bad:
if (error) {
vput(vp);
vp = NULL;
}
out:
pathbuf_stringcopy_put(nd.ni_pathbuf, pathstring);
switch (error) {
case EDUPFD:
case EMOVEFD:
/* if the caller isn't prepared to handle fds, fail for them */
if (ret_fd == NULL) {
error = EOPNOTSUPP;
break;
}
*ret_vp = NULL;
*ret_domove = error == EMOVEFD;
*ret_fd = l->l_dupfd;
error = 0;
break;
case 0:
KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
*ret_vp = vp;
break;
}
l->l_dupfd = 0;
return error;
}
/*
* Check for write permissions on the specified vnode.
* Prototype text segments cannot be written.
*/
int
vn_writechk(struct vnode *vp)
{
/*
* If the vnode is in use as a process's text,
* we can't allow writing.
*/
if (vp->v_iflag & VI_TEXT)
return ETXTBSY;
return 0;
}
int
vn_openchk(struct vnode *vp, kauth_cred_t cred, int fflags)
{
int permbits = 0;
int error;
if (vp->v_type == VNON || vp->v_type == VBAD)
return ENXIO;
if ((fflags & O_DIRECTORY) != 0 && vp->v_type != VDIR)
return ENOTDIR;
if ((fflags & O_REGULAR) != 0 && vp->v_type != VREG)
return EFTYPE;
if ((fflags & FREAD) != 0) {
permbits = VREAD;
}
if ((fflags & FEXEC) != 0) {
permbits |= VEXEC;
}
if ((fflags & (FWRITE | O_TRUNC)) != 0) {
permbits |= VWRITE;
if (vp->v_type == VDIR) {
error = EISDIR;
goto bad;
}
error = vn_writechk(vp);
if (error != 0)
goto bad;
}
error = VOP_ACCESS(vp, permbits, cred);
bad:
return error;
}
/*
* Mark a vnode as having executable mappings.
*/
void
vn_markexec(struct vnode *vp)
{
if ((vp->v_iflag & VI_EXECMAP) != 0) {
/* Safe unlocked, as long as caller holds a reference. */
return;
}
rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
mutex_enter(vp->v_interlock);
if ((vp->v_iflag & VI_EXECMAP) == 0) {
cpu_count(CPU_COUNT_EXECPAGES, vp->v_uobj.uo_npages);
vp->v_iflag |= VI_EXECMAP;
}
mutex_exit(vp->v_interlock);
rw_exit(vp->v_uobj.vmobjlock);
}
/*
* Mark a vnode as being the text of a process.
* Fail if the vnode is currently writable.
*/
int
vn_marktext(struct vnode *vp)
{
if ((vp->v_iflag & (VI_TEXT|VI_EXECMAP)) == (VI_TEXT|VI_EXECMAP)) {
/* Safe unlocked, as long as caller holds a reference. */
return 0;
}
rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
mutex_enter(vp->v_interlock);
if (vp->v_writecount != 0) {
KASSERT((vp->v_iflag & VI_TEXT) == 0);
mutex_exit(vp->v_interlock);
rw_exit(vp->v_uobj.vmobjlock);
return ETXTBSY;
}
if ((vp->v_iflag & VI_EXECMAP) == 0) {
cpu_count(CPU_COUNT_EXECPAGES, vp->v_uobj.uo_npages);
}
vp->v_iflag |= (VI_TEXT | VI_EXECMAP);
mutex_exit(vp->v_interlock);
rw_exit(vp->v_uobj.vmobjlock);
return 0;
}
/*
* Vnode close call
*
* Note: takes an unlocked vnode, while VOP_CLOSE takes a locked node.
*/
int
vn_close(struct vnode *vp, int flags, kauth_cred_t cred)
{
int error;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
if (flags & FWRITE) {
mutex_enter(vp->v_interlock);
KASSERT(vp->v_writecount > 0);
vp->v_writecount--;
mutex_exit(vp->v_interlock);
}
error = VOP_CLOSE(vp, flags, cred);
vput(vp);
return error;
}
static int
enforce_rlimit_fsize(struct vnode *vp, struct uio *uio, int ioflag)
{
struct lwp *l = curlwp;
off_t testoff;
if (uio->uio_rw != UIO_WRITE || vp->v_type != VREG)
return 0;
KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
if (ioflag & IO_APPEND)
testoff = vp->v_size;
else
testoff = uio->uio_offset;
if (testoff + uio->uio_resid >
l->l_proc->p_rlimit[RLIMIT_FSIZE].rlim_cur) {
mutex_enter(&proc_lock);
psignal(l->l_proc, SIGXFSZ);
mutex_exit(&proc_lock);
return EFBIG;
}
return 0;
}
/*
* 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, void *base, int len, off_t offset,
enum uio_seg segflg, int ioflg, kauth_cred_t cred, size_t *aresid,
struct lwp *l)
{
struct uio auio;
struct iovec aiov;
int error;
if ((ioflg & IO_NODELOCKED) == 0) {
if (rw == UIO_READ) {
vn_lock(vp, LK_SHARED | LK_RETRY);
} else /* UIO_WRITE */ {
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
}
}
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_rw = rw;
if (segflg == UIO_SYSSPACE) {
UIO_SETUP_SYSSPACE(&auio);
} else {
auio.uio_vmspace = l->l_proc->p_vmspace;
}
if ((error = enforce_rlimit_fsize(vp, &auio, ioflg)) != 0)
goto out;
if (rw == UIO_READ) {
error = VOP_READ(vp, &auio, ioflg, cred);
} else {
error = VOP_WRITE(vp, &auio, ioflg, cred);
}
if (aresid)
*aresid = auio.uio_resid;
else
if (auio.uio_resid && error == 0)
error = EIO;
out:
if ((ioflg & IO_NODELOCKED) == 0) {
VOP_UNLOCK(vp);
}
return error;
}
int
vn_readdir(file_t *fp, char *bf, int segflg, u_int count, int *done,
struct lwp *l, off_t **cookies, int *ncookies)
{
struct vnode *vp = fp->f_vnode;
struct iovec aiov;
struct uio auio;
int error, eofflag;
/* Limit the size on any kernel buffers used by VOP_READDIR */
count = uimin(MAXBSIZE, count);
unionread:
if (vp->v_type != VDIR)
return EINVAL;
aiov.iov_base = bf;
aiov.iov_len = count;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_rw = UIO_READ;
if (segflg == UIO_SYSSPACE) {
UIO_SETUP_SYSSPACE(&auio);
} else {
KASSERT(l == curlwp);
auio.uio_vmspace = l->l_proc->p_vmspace;
}
auio.uio_resid = count;
vn_lock(vp, LK_SHARED | LK_RETRY);
mutex_enter(&fp->f_lock);
auio.uio_offset = fp->f_offset;
mutex_exit(&fp->f_lock);
error = VOP_READDIR(vp, &auio, fp->f_cred, &eofflag, cookies,
ncookies);
mutex_enter(&fp->f_lock);
fp->f_offset = auio.uio_offset;
mutex_exit(&fp->f_lock);
VOP_UNLOCK(vp);
if (error)
return error;
if (count == auio.uio_resid && vn_union_readdir_hook) {
struct vnode *ovp = vp;
error = (*vn_union_readdir_hook)(&vp, fp, l);
if (error)
return error;
if (vp != ovp)
goto unionread;
}
if (count == auio.uio_resid && (vp->v_vflag & VV_ROOT) &&
(vp->v_mount->mnt_flag & MNT_UNION)) {
struct vnode *tvp = vp;
vp = vp->v_mount->mnt_vnodecovered;
vref(vp);
mutex_enter(&fp->f_lock);
fp->f_vnode = vp;
fp->f_offset = 0;
mutex_exit(&fp->f_lock);
vrele(tvp);
goto unionread;
}
*done = count - auio.uio_resid;
return error;
}
/*
* File table vnode read routine.
*/
static int
vn_read(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
int flags)
{
struct vnode *vp = fp->f_vnode;
int error, ioflag, fflag;
size_t count;
ioflag = IO_ADV_ENCODE(fp->f_advice);
fflag = fp->f_flag;
if (fflag & FNONBLOCK)
ioflag |= IO_NDELAY;
if ((fflag & (FFSYNC | FRSYNC)) == (FFSYNC | FRSYNC))
ioflag |= IO_SYNC;
if (fflag & FALTIO)
ioflag |= IO_ALTSEMANTICS;
if (fflag & FDIRECT)
ioflag |= IO_DIRECT;
if (offset == &fp->f_offset && (flags & FOF_UPDATE_OFFSET) != 0)
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
else
vn_lock(vp, LK_SHARED | LK_RETRY);
if (__predict_false(vp->v_type == VDIR) &&
offset == &fp->f_offset && (flags & FOF_UPDATE_OFFSET) == 0)
mutex_enter(&fp->f_lock);
uio->uio_offset = *offset;
if (__predict_false(vp->v_type == VDIR) &&
offset == &fp->f_offset && (flags & FOF_UPDATE_OFFSET) == 0)
mutex_enter(&fp->f_lock);
count = uio->uio_resid;
error = VOP_READ(vp, uio, ioflag, cred);
if (flags & FOF_UPDATE_OFFSET)
*offset += count - uio->uio_resid;
VOP_UNLOCK(vp);
return error;
}
/*
* File table vnode write routine.
*/
static int
vn_write(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
int flags)
{
struct vnode *vp = fp->f_vnode;
int error, ioflag, fflag;
size_t count;
ioflag = IO_ADV_ENCODE(fp->f_advice) | IO_UNIT;
fflag = fp->f_flag;
if (vp->v_type == VREG && (fflag & O_APPEND))
ioflag |= IO_APPEND;
if (fflag & FNONBLOCK)
ioflag |= IO_NDELAY;
if (fflag & FFSYNC ||
(vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
ioflag |= IO_SYNC;
else if (fflag & FDSYNC)
ioflag |= IO_DSYNC;
if (fflag & FALTIO)
ioflag |= IO_ALTSEMANTICS;
if (fflag & FDIRECT)
ioflag |= IO_DIRECT;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
uio->uio_offset = *offset;
count = uio->uio_resid;
if ((error = enforce_rlimit_fsize(vp, uio, ioflag)) != 0)
goto out;
error = VOP_WRITE(vp, uio, ioflag, cred);
if (flags & FOF_UPDATE_OFFSET) {
if (ioflag & IO_APPEND) {
/*
* SUSv3 describes behaviour for count = 0 as following:
* "Before any action ... is taken, and if nbyte is zero
* and the file is a regular file, the write() function
* ... in the absence of errors ... shall return zero
* and have no other results."
*/
if (count)
*offset = uio->uio_offset;
} else
*offset += count - uio->uio_resid;
}
out:
VOP_UNLOCK(vp);
return error;
}
/*
* File table vnode stat routine.
*/
static int
vn_statfile(file_t *fp, struct stat *sb)
{
struct vnode *vp = fp->f_vnode;
int error;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
error = vn_stat(vp, sb);
VOP_UNLOCK(vp);
return error;
}
int
vn_stat(struct vnode *vp, struct stat *sb)
{
struct vattr va;
int error;
mode_t mode;
memset(&va, 0, sizeof(va));
error = VOP_GETATTR(vp, &va, kauth_cred_get());
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_atimespec = va.va_atime;
sb->st_mtimespec = va.va_mtime;
sb->st_ctimespec = va.va_ctime;
sb->st_birthtimespec = va.va_birthtime;
sb->st_blksize = va.va_blocksize;
sb->st_flags = va.va_flags;
sb->st_gen = 0;
sb->st_blocks = va.va_bytes / S_BLKSIZE;
return 0;
}
/*
* File table vnode fcntl routine.
*/
static int
vn_fcntl(file_t *fp, u_int com, void *data)
{
struct vnode *vp = fp->f_vnode;
int error;
error = VOP_FCNTL(vp, com, data, fp->f_flag, kauth_cred_get());
return error;
}
/*
* File table vnode ioctl routine.
*/
static int
vn_ioctl(file_t *fp, u_long com, void *data)
{
struct vnode *vp = fp->f_vnode, *ovp;
struct vattr vattr;
int error;
switch (vp->v_type) {
case VREG:
case VDIR:
if (com == FIONREAD) {
vn_lock(vp, LK_SHARED | LK_RETRY);
error = VOP_GETATTR(vp, &vattr, kauth_cred_get());
if (error == 0) {
if (vp->v_type == VDIR)
mutex_enter(&fp->f_lock);
*(int *)data = vattr.va_size - fp->f_offset;
if (vp->v_type == VDIR)
mutex_exit(&fp->f_lock);
}
VOP_UNLOCK(vp);
if (error)
return error;
return 0;
}
if ((com == FIONWRITE) || (com == FIONSPACE)) {
/*
* Files don't have send queues, so there never
* are any bytes in them, nor is there any
* open space in them.
*/
*(int *)data = 0;
return 0;
}
if (com == FIOGETBMAP) {
daddr_t *block;
if (*(daddr_t *)data < 0)
return EINVAL;
block = (daddr_t *)data;
vn_lock(vp, LK_SHARED | LK_RETRY);
error = VOP_BMAP(vp, *block, NULL, block, NULL);
VOP_UNLOCK(vp);
return error;
}
if (com == OFIOGETBMAP) {
daddr_t ibn, obn;
if (*(int32_t *)data < 0)
return EINVAL;
ibn = (daddr_t)*(int32_t *)data;
vn_lock(vp, LK_SHARED | LK_RETRY);
error = VOP_BMAP(vp, ibn, NULL, &obn, NULL);
VOP_UNLOCK(vp);
*(int32_t *)data = (int32_t)obn;
return error;
}
if (com == FIONBIO || com == FIOASYNC) /* XXX */
return 0; /* XXX */
/* FALLTHROUGH */
case VFIFO:
case VCHR:
case VBLK:
error = VOP_IOCTL(vp, com, data, fp->f_flag,
kauth_cred_get());
if (error == 0 && com == TIOCSCTTY) {
vref(vp);
mutex_enter(&proc_lock);
ovp = curproc->p_session->s_ttyvp;
curproc->p_session->s_ttyvp = vp;
mutex_exit(&proc_lock);
if (ovp != NULL)
vrele(ovp);
}
return error;
default:
return EPASSTHROUGH;
}
}
/*
* File table vnode poll routine.
*/
static int
vn_poll(file_t *fp, int events)
{
return VOP_POLL(fp->f_vnode, events);
}
/*
* File table vnode kqfilter routine.
*/
int
vn_kqfilter(file_t *fp, struct knote *kn)
{
return VOP_KQFILTER(fp->f_vnode, kn);
}
static int
vn_mmap(struct file *fp, off_t *offp, size_t size, int prot, int *flagsp,
int *advicep, struct uvm_object **uobjp, int *maxprotp)
{
struct uvm_object *uobj;
struct vnode *vp;
struct vattr va;
struct lwp *l;
vm_prot_t maxprot;
off_t off;
int error, flags;
bool needwritemap;
l = curlwp;
off = *offp;
flags = *flagsp;
maxprot = VM_PROT_EXECUTE;
KASSERT(size > 0);
vp = fp->f_vnode;
if (vp->v_type != VREG && vp->v_type != VCHR &&
vp->v_type != VBLK) {
/* only REG/CHR/BLK support mmap */
return ENODEV;
}
if (vp->v_type != VCHR && off < 0) {
return EINVAL;
}
#if SIZE_MAX > UINT32_MAX /* XXX -Wtype-limits */
if (vp->v_type != VCHR && size > __type_max(off_t)) {
return EOVERFLOW;
}
#endif
if (vp->v_type != VCHR && off > __type_max(off_t) - size) {
/* no offset wrapping */
return EOVERFLOW;
}
/* special case: catch SunOS style /dev/zero */
if (vp->v_type == VCHR &&
(vp->v_rdev == zerodev || COMPAT_ZERODEV(vp->v_rdev))) {
*uobjp = NULL;
*maxprotp = VM_PROT_ALL;
return 0;
}
/*
* Old programs may not select a specific sharing type, so
* default to an appropriate one.
*
* XXX: how does MAP_ANON fit in the picture?
*/
if ((flags & (MAP_SHARED|MAP_PRIVATE)) == 0) {
#if defined(DEBUG)
struct proc *p = l->l_proc;
printf("WARNING: defaulted mmap() share type to "
"%s (pid %d command %s)\n", vp->v_type == VCHR ?
"MAP_SHARED" : "MAP_PRIVATE", p->p_pid,
p->p_comm);
#endif
if (vp->v_type == VCHR)
flags |= MAP_SHARED; /* for a device */
else
flags |= MAP_PRIVATE; /* for a file */
}
/*