/* * Copyright (c) 1982, 1986, 1989, 1991, 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. 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 8.6 (Berkeley) 4/19/94 * $Id: kern_descrip.c,v 1.8 1995/02/20 19:42:33 guido Exp $ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include int finishdup(struct filedesc *fdp, int old, int new, int *retval); /* * 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 */ int getdtablesize(p, uap, retval) struct proc *p; struct getdtablesize_args *uap; int *retval; { *retval = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); return (0); } /* * Duplicate a file descriptor to a particular value. */ struct dup2_args { u_int from; u_int to; }; /* ARGSUSED */ int 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 >= maxfilesperproc) 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)); } /* * Duplicate a file descriptor. */ struct dup_args { u_int fd; }; /* ARGSUSED */ int 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; #if 0 /* * XXX Compatibility */ if (old &~ 077) { uap->fd &= 077; return (dup2(p, uap, retval)); } #endif 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)); } /* * The file control system call. */ struct fcntl_args { int fd; int cmd; int arg; }; /* ARGSUSED */ int 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 >= maxfilesperproc) 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 |= P_ADVLOCK; 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 |= P_ADVLOCK; 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. */ /* ARGSUSED */ int 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 */ int 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 */ int 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 */ int 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; int 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, maxfilesperproc); 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++; } return (0); } /* * Check to see whether n user file descriptors * are available to the process p. */ int 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, maxfilesperproc); 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. */ int 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); bzero(fp, sizeof(struct file)); 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_cred = p->p_ucred; crhold(fp->f_cred); if (resultfp) *resultfp = fp; if (resultfd) *resultfd = i; return (0); } /* * Free a file descriptor. */ void 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); } /* * Close any files on exec? */ void fdcloseexec(p) struct proc *p; { struct filedesc *fdp = p->p_fd; struct file **fpp; char *fdfp; register int i; fpp = fdp->fd_ofiles; fdfp = fdp->fd_ofileflags; for (i = 0; i <= fdp->fd_lastfile; i++, fpp++, fdfp++) if (*fpp != NULL && (*fdfp & UF_EXCLOSE)) { if (*fdfp & UF_MAPPED) (void) munmapfd(p, i); (void) closef(*fpp, p); *fpp = NULL; *fdfp = 0; if (i < fdp->fd_freefile) fdp->fd_freefile = i; } while (fdp->fd_lastfile > 0 && fdp->fd_ofiles[fdp->fd_lastfile] == NULL) fdp->fd_lastfile--; } /* * 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. */ int 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 & P_ADVLOCK) && 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); } if (fp->f_ops) error = (*fp->f_ops->fo_close)(fp, p); else error = 0; 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 */ int 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; 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 */ int 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. */ int 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 */ }