4.4BSD/usr/src/sys/kern/kern_descrip.c
/*
* Copyright (c) 1982, 1986, 1989, 1991, 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*
* @(#)kern_descrip.c 8.1 (Berkeley) 6/10/93
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/syslog.h>
#include <sys/unistd.h>
#include <sys/resourcevar.h>
/*
* Descriptor management.
*/
struct file *filehead; /* head of list of open files */
int nfiles; /* actual number of open files */
/*
* System calls on descriptors.
*/
struct getdtablesize_args {
int dummy;
};
/* ARGSUSED */
getdtablesize(p, uap, retval)
struct proc *p;
struct getdtablesize_args *uap;
int *retval;
{
*retval = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfiles);
return (0);
}
/*
* Duplicate a file descriptor.
*/
struct dup_args {
u_int fd;
};
/* ARGSUSED */
dup(p, uap, retval)
struct proc *p;
struct dup_args *uap;
int *retval;
{
register struct filedesc *fdp;
u_int old;
int new, error;
old = uap->fd;
/*
* XXX Compatibility
*/
if (old &~ 077) { uap->fd &= 077; return (dup2(p, uap, retval)); }
fdp = p->p_fd;
if (old >= fdp->fd_nfiles || fdp->fd_ofiles[old] == NULL)
return (EBADF);
if (error = fdalloc(p, 0, &new))
return (error);
return (finishdup(fdp, (int)old, new, retval));
}
/*
* Duplicate a file descriptor to a particular value.
*/
struct dup2_args {
u_int from;
u_int to;
};
/* ARGSUSED */
dup2(p, uap, retval)
struct proc *p;
struct dup2_args *uap;
int *retval;
{
register struct filedesc *fdp = p->p_fd;
register u_int old = uap->from, new = uap->to;
int i, error;
if (old >= fdp->fd_nfiles ||
fdp->fd_ofiles[old] == NULL ||
new >= p->p_rlimit[RLIMIT_NOFILE].rlim_cur ||
new >= maxfiles)
return (EBADF);
if (old == new) {
*retval = new;
return (0);
}
if (new >= fdp->fd_nfiles) {
if (error = fdalloc(p, new, &i))
return (error);
if (new != i)
panic("dup2: fdalloc");
} else if (fdp->fd_ofiles[new]) {
if (fdp->fd_ofileflags[new] & UF_MAPPED)
(void) munmapfd(p, new);
/*
* dup2() must succeed even if the close has an error.
*/
(void) closef(fdp->fd_ofiles[new], p);
}
return (finishdup(fdp, (int)old, (int)new, retval));
}
/*
* The file control system call.
*/
struct fcntl_args {
int fd;
int cmd;
int arg;
};
/* ARGSUSED */
fcntl(p, uap, retval)
struct proc *p;
register struct fcntl_args *uap;
int *retval;
{
register struct filedesc *fdp = p->p_fd;
register struct file *fp;
register char *pop;
struct vnode *vp;
int i, tmp, error, flg = F_POSIX;
struct flock fl;
u_int newmin;
if ((unsigned)uap->fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[uap->fd]) == NULL)
return (EBADF);
pop = &fdp->fd_ofileflags[uap->fd];
switch (uap->cmd) {
case F_DUPFD:
newmin = uap->arg;
if (newmin >= p->p_rlimit[RLIMIT_NOFILE].rlim_cur ||
newmin >= maxfiles)
return (EINVAL);
if (error = fdalloc(p, newmin, &i))
return (error);
return (finishdup(fdp, uap->fd, i, retval));
case F_GETFD:
*retval = *pop & 1;
return (0);
case F_SETFD:
*pop = (*pop &~ 1) | (uap->arg & 1);
return (0);
case F_GETFL:
*retval = OFLAGS(fp->f_flag);
return (0);
case F_SETFL:
fp->f_flag &= ~FCNTLFLAGS;
fp->f_flag |= FFLAGS(uap->arg) & FCNTLFLAGS;
tmp = fp->f_flag & FNONBLOCK;
error = (*fp->f_ops->fo_ioctl)(fp, FIONBIO, (caddr_t)&tmp, p);
if (error)
return (error);
tmp = fp->f_flag & FASYNC;
error = (*fp->f_ops->fo_ioctl)(fp, FIOASYNC, (caddr_t)&tmp, p);
if (!error)
return (0);
fp->f_flag &= ~FNONBLOCK;
tmp = 0;
(void) (*fp->f_ops->fo_ioctl)(fp, FIONBIO, (caddr_t)&tmp, p);
return (error);
case F_GETOWN:
if (fp->f_type == DTYPE_SOCKET) {
*retval = ((struct socket *)fp->f_data)->so_pgid;
return (0);
}
error = (*fp->f_ops->fo_ioctl)
(fp, (int)TIOCGPGRP, (caddr_t)retval, p);
*retval = -*retval;
return (error);
case F_SETOWN:
if (fp->f_type == DTYPE_SOCKET) {
((struct socket *)fp->f_data)->so_pgid = uap->arg;
return (0);
}
if (uap->arg <= 0) {
uap->arg = -uap->arg;
} else {
struct proc *p1 = pfind(uap->arg);
if (p1 == 0)
return (ESRCH);
uap->arg = p1->p_pgrp->pg_id;
}
return ((*fp->f_ops->fo_ioctl)
(fp, (int)TIOCSPGRP, (caddr_t)&uap->arg, p));
case F_SETLKW:
flg |= F_WAIT;
/* Fall into F_SETLK */
case F_SETLK:
if (fp->f_type != DTYPE_VNODE)
return (EBADF);
vp = (struct vnode *)fp->f_data;
/* Copy in the lock structure */
error = copyin((caddr_t)uap->arg, (caddr_t)&fl, sizeof (fl));
if (error)
return (error);
if (fl.l_whence == SEEK_CUR)
fl.l_start += fp->f_offset;
switch (fl.l_type) {
case F_RDLCK:
if ((fp->f_flag & FREAD) == 0)
return (EBADF);
p->p_flag |= SADVLCK;
return (VOP_ADVLOCK(vp, (caddr_t)p, F_SETLK, &fl, flg));
case F_WRLCK:
if ((fp->f_flag & FWRITE) == 0)
return (EBADF);
p->p_flag |= SADVLCK;
return (VOP_ADVLOCK(vp, (caddr_t)p, F_SETLK, &fl, flg));
case F_UNLCK:
return (VOP_ADVLOCK(vp, (caddr_t)p, F_UNLCK, &fl,
F_POSIX));
default:
return (EINVAL);
}
case F_GETLK:
if (fp->f_type != DTYPE_VNODE)
return (EBADF);
vp = (struct vnode *)fp->f_data;
/* Copy in the lock structure */
error = copyin((caddr_t)uap->arg, (caddr_t)&fl, sizeof (fl));
if (error)
return (error);
if (fl.l_whence == SEEK_CUR)
fl.l_start += fp->f_offset;
if (error = VOP_ADVLOCK(vp, (caddr_t)p, F_GETLK, &fl, F_POSIX))
return (error);
return (copyout((caddr_t)&fl, (caddr_t)uap->arg, sizeof (fl)));
default:
return (EINVAL);
}
/* NOTREACHED */
}
/*
* Common code for dup, dup2, and fcntl(F_DUPFD).
*/
int
finishdup(fdp, old, new, retval)
register struct filedesc *fdp;
register int old, new, *retval;
{
register struct file *fp;
fp = fdp->fd_ofiles[old];
fdp->fd_ofiles[new] = fp;
fdp->fd_ofileflags[new] = fdp->fd_ofileflags[old] &~ UF_EXCLOSE;
fp->f_count++;
if (new > fdp->fd_lastfile)
fdp->fd_lastfile = new;
*retval = new;
return (0);
}
/*
* Close a file descriptor.
*/
struct close_args {
int fd;
};
/* ARGSUSED */
close(p, uap, retval)
struct proc *p;
struct close_args *uap;
int *retval;
{
register struct filedesc *fdp = p->p_fd;
register struct file *fp;
register int fd = uap->fd;
register u_char *pf;
if ((unsigned)fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[fd]) == NULL)
return (EBADF);
pf = (u_char *)&fdp->fd_ofileflags[fd];
if (*pf & UF_MAPPED)
(void) munmapfd(p, fd);
fdp->fd_ofiles[fd] = NULL;
while (fdp->fd_lastfile > 0 && fdp->fd_ofiles[fdp->fd_lastfile] == NULL)
fdp->fd_lastfile--;
if (fd < fdp->fd_freefile)
fdp->fd_freefile = fd;
*pf = 0;
return (closef(fp, p));
}
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
/*
* Return status information about a file descriptor.
*/
struct ofstat_args {
int fd;
struct ostat *sb;
};
/* ARGSUSED */
ofstat(p, uap, retval)
struct proc *p;
register struct ofstat_args *uap;
int *retval;
{
register struct filedesc *fdp = p->p_fd;
register struct file *fp;
struct stat ub;
struct ostat oub;
int error;
if ((unsigned)uap->fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[uap->fd]) == NULL)
return (EBADF);
switch (fp->f_type) {
case DTYPE_VNODE:
error = vn_stat((struct vnode *)fp->f_data, &ub, p);
break;
case DTYPE_SOCKET:
error = soo_stat((struct socket *)fp->f_data, &ub);
break;
default:
panic("ofstat");
/*NOTREACHED*/
}
cvtstat(&ub, &oub);
if (error == 0)
error = copyout((caddr_t)&oub, (caddr_t)uap->sb, sizeof (oub));
return (error);
}
#endif /* COMPAT_43 || COMPAT_SUNOS */
/*
* Return status information about a file descriptor.
*/
struct fstat_args {
int fd;
struct stat *sb;
};
/* ARGSUSED */
fstat(p, uap, retval)
struct proc *p;
register struct fstat_args *uap;
int *retval;
{
register struct filedesc *fdp = p->p_fd;
register struct file *fp;
struct stat ub;
int error;
if ((unsigned)uap->fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[uap->fd]) == NULL)
return (EBADF);
switch (fp->f_type) {
case DTYPE_VNODE:
error = vn_stat((struct vnode *)fp->f_data, &ub, p);
break;
case DTYPE_SOCKET:
error = soo_stat((struct socket *)fp->f_data, &ub);
break;
default:
panic("fstat");
/*NOTREACHED*/
}
if (error == 0)
error = copyout((caddr_t)&ub, (caddr_t)uap->sb, sizeof (ub));
return (error);
}
/*
* Return pathconf information about a file descriptor.
*/
struct fpathconf_args {
int fd;
int name;
};
/* ARGSUSED */
fpathconf(p, uap, retval)
struct proc *p;
register struct fpathconf_args *uap;
int *retval;
{
struct filedesc *fdp = p->p_fd;
struct file *fp;
struct vnode *vp;
if ((unsigned)uap->fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[uap->fd]) == NULL)
return (EBADF);
switch (fp->f_type) {
case DTYPE_SOCKET:
if (uap->name != _PC_PIPE_BUF)
return (EINVAL);
*retval = PIPE_BUF;
return (0);
case DTYPE_VNODE:
vp = (struct vnode *)fp->f_data;
return (VOP_PATHCONF(vp, uap->name, retval));
default:
panic("fpathconf");
}
/*NOTREACHED*/
}
/*
* Allocate a file descriptor for the process.
*/
int fdexpand;
fdalloc(p, want, result)
struct proc *p;
int want;
int *result;
{
register struct filedesc *fdp = p->p_fd;
register int i;
int lim, last, nfiles;
struct file **newofile;
char *newofileflags;
/*
* Search for a free descriptor starting at the higher
* of want or fd_freefile. If that fails, consider
* expanding the ofile array.
*/
lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfiles);
for (;;) {
last = min(fdp->fd_nfiles, lim);
if ((i = want) < fdp->fd_freefile)
i = fdp->fd_freefile;
for (; i < last; i++) {
if (fdp->fd_ofiles[i] == NULL) {
fdp->fd_ofileflags[i] = 0;
if (i > fdp->fd_lastfile)
fdp->fd_lastfile = i;
if (want <= fdp->fd_freefile)
fdp->fd_freefile = i;
*result = i;
return (0);
}
}
/*
* No space in current array. Expand?
*/
if (fdp->fd_nfiles >= lim)
return (EMFILE);
if (fdp->fd_nfiles < NDEXTENT)
nfiles = NDEXTENT;
else
nfiles = 2 * fdp->fd_nfiles;
MALLOC(newofile, struct file **, nfiles * OFILESIZE,
M_FILEDESC, M_WAITOK);
newofileflags = (char *) &newofile[nfiles];
/*
* Copy the existing ofile and ofileflags arrays
* and zero the new portion of each array.
*/
bcopy(fdp->fd_ofiles, newofile,
(i = sizeof(struct file *) * fdp->fd_nfiles));
bzero((char *)newofile + i, nfiles * sizeof(struct file *) - i);
bcopy(fdp->fd_ofileflags, newofileflags,
(i = sizeof(char) * fdp->fd_nfiles));
bzero(newofileflags + i, nfiles * sizeof(char) - i);
if (fdp->fd_nfiles > NDFILE)
FREE(fdp->fd_ofiles, M_FILEDESC);
fdp->fd_ofiles = newofile;
fdp->fd_ofileflags = newofileflags;
fdp->fd_nfiles = nfiles;
fdexpand++;
}
}
/*
* Check to see whether n user file descriptors
* are available to the process p.
*/
fdavail(p, n)
struct proc *p;
register int n;
{
register struct filedesc *fdp = p->p_fd;
register struct file **fpp;
register int i, lim;
lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfiles);
if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0)
return (1);
fpp = &fdp->fd_ofiles[fdp->fd_freefile];
for (i = fdp->fd_nfiles - fdp->fd_freefile; --i >= 0; fpp++)
if (*fpp == NULL && --n <= 0)
return (1);
return (0);
}
/*
* Create a new open file structure and allocate
* a file decriptor for the process that refers to it.
*/
falloc(p, resultfp, resultfd)
register struct proc *p;
struct file **resultfp;
int *resultfd;
{
register struct file *fp, *fq, **fpp;
int error, i;
if (error = fdalloc(p, 0, &i))
return (error);
if (nfiles >= maxfiles) {
tablefull("file");
return (ENFILE);
}
/*
* Allocate a new file descriptor.
* If the process has file descriptor zero open, add to the list
* of open files at that point, otherwise put it at the front of
* the list of open files.
*/
nfiles++;
MALLOC(fp, struct file *, sizeof(struct file), M_FILE, M_WAITOK);
if (fq = p->p_fd->fd_ofiles[0])
fpp = &fq->f_filef;
else
fpp = &filehead;
p->p_fd->fd_ofiles[i] = fp;
if (fq = *fpp)
fq->f_fileb = &fp->f_filef;
fp->f_filef = fq;
fp->f_fileb = fpp;
*fpp = fp;
fp->f_count = 1;
fp->f_msgcount = 0;
fp->f_offset = 0;
fp->f_cred = p->p_ucred;
crhold(fp->f_cred);
if (resultfp)
*resultfp = fp;
if (resultfd)
*resultfd = i;
return (0);
}
/*
* Free a file descriptor.
*/
ffree(fp)
register struct file *fp;
{
register struct file *fq;
if (fq = fp->f_filef)
fq->f_fileb = fp->f_fileb;
*fp->f_fileb = fq;
crfree(fp->f_cred);
#ifdef DIAGNOSTIC
fp->f_filef = NULL;
fp->f_fileb = NULL;
fp->f_count = 0;
#endif
nfiles--;
FREE(fp, M_FILE);
}
/*
* Copy a filedesc structure.
*/
struct filedesc *
fdcopy(p)
struct proc *p;
{
register struct filedesc *newfdp, *fdp = p->p_fd;
register struct file **fpp;
register int i;
MALLOC(newfdp, struct filedesc *, sizeof(struct filedesc0),
M_FILEDESC, M_WAITOK);
bcopy(fdp, newfdp, sizeof(struct filedesc));
VREF(newfdp->fd_cdir);
if (newfdp->fd_rdir)
VREF(newfdp->fd_rdir);
newfdp->fd_refcnt = 1;
/*
* If the number of open files fits in the internal arrays
* of the open file structure, use them, otherwise allocate
* additional memory for the number of descriptors currently
* in use.
*/
if (newfdp->fd_lastfile < NDFILE) {
newfdp->fd_ofiles = ((struct filedesc0 *) newfdp)->fd_dfiles;
newfdp->fd_ofileflags =
((struct filedesc0 *) newfdp)->fd_dfileflags;
i = NDFILE;
} else {
/*
* Compute the smallest multiple of NDEXTENT needed
* for the file descriptors currently in use,
* allowing the table to shrink.
*/
i = newfdp->fd_nfiles;
while (i > 2 * NDEXTENT && i >= newfdp->fd_lastfile * 2)
i /= 2;
MALLOC(newfdp->fd_ofiles, struct file **, i * OFILESIZE,
M_FILEDESC, M_WAITOK);
newfdp->fd_ofileflags = (char *) &newfdp->fd_ofiles[i];
}
newfdp->fd_nfiles = i;
bcopy(fdp->fd_ofiles, newfdp->fd_ofiles, i * sizeof(struct file **));
bcopy(fdp->fd_ofileflags, newfdp->fd_ofileflags, i * sizeof(char));
fpp = newfdp->fd_ofiles;
for (i = newfdp->fd_lastfile; i-- >= 0; fpp++)
if (*fpp != NULL)
(*fpp)->f_count++;
return (newfdp);
}
/*
* Release a filedesc structure.
*/
void
fdfree(p)
struct proc *p;
{
register struct filedesc *fdp = p->p_fd;
struct file **fpp;
register int i;
if (--fdp->fd_refcnt > 0)
return;
fpp = fdp->fd_ofiles;
for (i = fdp->fd_lastfile; i-- >= 0; fpp++)
if (*fpp)
(void) closef(*fpp, p);
if (fdp->fd_nfiles > NDFILE)
FREE(fdp->fd_ofiles, M_FILEDESC);
vrele(fdp->fd_cdir);
if (fdp->fd_rdir)
vrele(fdp->fd_rdir);
FREE(fdp, M_FILEDESC);
}
/*
* Internal form of close.
* Decrement reference count on file structure.
* Note: p may be NULL when closing a file
* that was being passed in a message.
*/
closef(fp, p)
register struct file *fp;
register struct proc *p;
{
struct vnode *vp;
struct flock lf;
int error;
if (fp == NULL)
return (0);
/*
* POSIX record locking dictates that any close releases ALL
* locks owned by this process. This is handled by setting
* a flag in the unlock to free ONLY locks obeying POSIX
* semantics, and not to free BSD-style file locks.
* If the descriptor was in a message, POSIX-style locks
* aren't passed with the descriptor.
*/
if (p && (p->p_flag & SADVLCK) && fp->f_type == DTYPE_VNODE) {
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
lf.l_type = F_UNLCK;
vp = (struct vnode *)fp->f_data;
(void) VOP_ADVLOCK(vp, (caddr_t)p, F_UNLCK, &lf, F_POSIX);
}
if (--fp->f_count > 0)
return (0);
if (fp->f_count < 0)
panic("closef: count < 0");
if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE) {
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
lf.l_type = F_UNLCK;
vp = (struct vnode *)fp->f_data;
(void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK);
}
error = (*fp->f_ops->fo_close)(fp, p);
ffree(fp);
return (error);
}
/*
* Apply an advisory lock on a file descriptor.
*
* Just attempt to get a record lock of the requested type on
* the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
*/
struct flock_args {
int fd;
int how;
};
/* ARGSUSED */
flock(p, uap, retval)
struct proc *p;
register struct flock_args *uap;
int *retval;
{
register struct filedesc *fdp = p->p_fd;
register struct file *fp;
struct vnode *vp;
struct flock lf;
int error;
if ((unsigned)uap->fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[uap->fd]) == NULL)
return (EBADF);
if (fp->f_type != DTYPE_VNODE)
return (EOPNOTSUPP);
vp = (struct vnode *)fp->f_data;
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
if (uap->how & LOCK_UN) {
lf.l_type = F_UNLCK;
fp->f_flag &= ~FHASLOCK;
return (VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK));
}
if (uap->how & LOCK_EX)
lf.l_type = F_WRLCK;
else if (uap->how & LOCK_SH)
lf.l_type = F_RDLCK;
else
return (EBADF);
fp->f_flag |= FHASLOCK;
if (uap->how & LOCK_NB)
return (VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_FLOCK));
return (VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_FLOCK|F_WAIT));
}
/*
* File Descriptor pseudo-device driver (/dev/fd/).
*
* Opening minor device N dup()s the file (if any) connected to file
* descriptor N belonging to the calling process. Note that this driver
* consists of only the ``open()'' routine, because all subsequent
* references to this file will be direct to the other driver.
*/
/* ARGSUSED */
fdopen(dev, mode, type, p)
dev_t dev;
int mode, type;
struct proc *p;
{
/*
* XXX Kludge: set curproc->p_dupfd to contain the value of the
* the file descriptor being sought for duplication. The error
* return ensures that the vnode for this device will be released
* by vn_open. Open will detect this special error and take the
* actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
* will simply report the error.
*/
p->p_dupfd = minor(dev);
return (ENODEV);
}
/*
* Duplicate the specified descriptor to a free descriptor.
*/
dupfdopen(fdp, indx, dfd, mode, error)
register struct filedesc *fdp;
register int indx, dfd;
int mode;
int error;
{
register struct file *wfp;
struct file *fp;
/*
* If the to-be-dup'd fd number is greater than the allowed number
* of file descriptors, or the fd to be dup'd has already been
* closed, reject. Note, check for new == old is necessary as
* falloc could allocate an already closed to-be-dup'd descriptor
* as the new descriptor.
*/
fp = fdp->fd_ofiles[indx];
if ((u_int)dfd >= fdp->fd_nfiles ||
(wfp = fdp->fd_ofiles[dfd]) == NULL || fp == wfp)
return (EBADF);
/*
* There are two cases of interest here.
*
* For ENODEV simply dup (dfd) to file descriptor
* (indx) and return.
*
* For ENXIO steal away the file structure from (dfd) and
* store it in (indx). (dfd) is effectively closed by
* this operation.
*
* Any other error code is just returned.
*/
switch (error) {
case ENODEV:
/*
* Check that the mode the file is being opened for is a
* subset of the mode of the existing descriptor.
*/
if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag)
return (EACCES);
fdp->fd_ofiles[indx] = wfp;
fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
wfp->f_count++;
if (indx > fdp->fd_lastfile)
fdp->fd_lastfile = indx;
return (0);
case ENXIO:
/*
* Steal away the file pointer from dfd, and stuff it into indx.
*/
fdp->fd_ofiles[indx] = fdp->fd_ofiles[dfd];
fdp->fd_ofiles[dfd] = NULL;
fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
fdp->fd_ofileflags[dfd] = 0;
/*
* Complete the clean up of the filedesc structure by
* recomputing the various hints.
*/
if (indx > fdp->fd_lastfile)
fdp->fd_lastfile = indx;
else
while (fdp->fd_lastfile > 0 &&
fdp->fd_ofiles[fdp->fd_lastfile] == NULL)
fdp->fd_lastfile--;
if (dfd < fdp->fd_freefile)
fdp->fd_freefile = dfd;
return (0);
default:
return (error);
}
/* NOTREACHED */
}