2 * Copyright (c) 2005 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * Copyright (c) 1982, 1986, 1989, 1991, 1993
36 * The Regents of the University of California. All rights reserved.
37 * (c) UNIX System Laboratories, Inc.
38 * All or some portions of this file are derived from material licensed
39 * to the University of California by American Telephone and Telegraph
40 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
41 * the permission of UNIX System Laboratories, Inc.
43 * Redistribution and use in source and binary forms, with or without
44 * modification, are permitted provided that the following conditions
46 * 1. Redistributions of source code must retain the above copyright
47 * notice, this list of conditions and the following disclaimer.
48 * 2. Redistributions in binary form must reproduce the above copyright
49 * notice, this list of conditions and the following disclaimer in the
50 * documentation and/or other materials provided with the distribution.
51 * 3. All advertising materials mentioning features or use of this software
52 * must display the following acknowledgement:
53 * This product includes software developed by the University of
54 * California, Berkeley and its contributors.
55 * 4. Neither the name of the University nor the names of its contributors
56 * may be used to endorse or promote products derived from this software
57 * without specific prior written permission.
59 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
62 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
71 * @(#)kern_descrip.c 8.6 (Berkeley) 4/19/94
72 * $FreeBSD: src/sys/kern/kern_descrip.c,v 1.81.2.19 2004/02/28 00:43:31 tegge Exp $
73 * $DragonFly: src/sys/kern/kern_descrip.c,v 1.79 2008/08/31 13:18:28 aggelos Exp $
76 #include "opt_compat.h"
77 #include <sys/param.h>
78 #include <sys/systm.h>
79 #include <sys/malloc.h>
80 #include <sys/sysproto.h>
82 #include <sys/device.h>
84 #include <sys/filedesc.h>
85 #include <sys/kernel.h>
86 #include <sys/sysctl.h>
87 #include <sys/vnode.h>
89 #include <sys/nlookup.h>
92 #include <sys/filio.h>
93 #include <sys/fcntl.h>
94 #include <sys/unistd.h>
95 #include <sys/resourcevar.h>
96 #include <sys/event.h>
97 #include <sys/kern_syscall.h>
98 #include <sys/kcore.h>
99 #include <sys/kinfo.h>
103 #include <vm/vm_extern.h>
105 #include <sys/thread2.h>
106 #include <sys/file2.h>
107 #include <sys/spinlock2.h>
108 #include <sys/mplock2.h>
110 static void fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd);
111 static void fdreserve_locked (struct filedesc *fdp, int fd0, int incr);
112 static struct file *funsetfd_locked (struct filedesc *fdp, int fd);
113 static void ffree(struct file *fp);
115 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table");
116 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader",
117 "file desc to leader structures");
118 MALLOC_DEFINE(M_FILE, "file", "Open file structure");
119 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");
121 static struct krate krate_uidinfo = { .freq = 1 };
123 static d_open_t fdopen;
126 #define CDEV_MAJOR 22
127 static struct dev_ops fildesc_ops = {
128 { "FD", CDEV_MAJOR, 0 },
133 * Descriptor management.
135 static struct filelist filehead = LIST_HEAD_INITIALIZER(&filehead);
136 static struct spinlock filehead_spin = SPINLOCK_INITIALIZER(&filehead_spin);
137 static int nfiles; /* actual number of open files */
141 * Fixup fd_freefile and fd_lastfile after a descriptor has been cleared.
143 * MPSAFE - must be called with fdp->fd_spin exclusively held
147 fdfixup_locked(struct filedesc *fdp, int fd)
149 if (fd < fdp->fd_freefile) {
150 fdp->fd_freefile = fd;
152 while (fdp->fd_lastfile >= 0 &&
153 fdp->fd_files[fdp->fd_lastfile].fp == NULL &&
154 fdp->fd_files[fdp->fd_lastfile].reserved == 0
161 * System calls on descriptors.
166 sys_getdtablesize(struct getdtablesize_args *uap)
168 struct proc *p = curproc;
169 struct plimit *limit = p->p_limit;
172 spin_lock_rd(&limit->p_spin);
173 if (limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
176 dtsize = (int)limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur;
177 spin_unlock_rd(&limit->p_spin);
178 if (dtsize > maxfilesperproc)
179 dtsize = maxfilesperproc;
180 if (dtsize < minfilesperproc)
181 dtsize = minfilesperproc;
182 if (p->p_ucred->cr_uid && dtsize > maxfilesperuser)
183 dtsize = maxfilesperuser;
184 uap->sysmsg_result = dtsize;
189 * Duplicate a file descriptor to a particular value.
191 * note: keep in mind that a potential race condition exists when closing
192 * descriptors from a shared descriptor table (via rfork).
197 sys_dup2(struct dup2_args *uap)
202 error = kern_dup(DUP_FIXED, uap->from, uap->to, &fd);
203 uap->sysmsg_fds[0] = fd;
209 * Duplicate a file descriptor.
214 sys_dup(struct dup_args *uap)
219 error = kern_dup(DUP_VARIABLE, uap->fd, 0, &fd);
220 uap->sysmsg_fds[0] = fd;
226 * MPALMOSTSAFE - acquires mplock for fp operations
229 kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred)
231 struct thread *td = curthread;
232 struct proc *p = td->td_proc;
238 int tmp, error, flg = F_POSIX;
243 * Operations on file descriptors that do not require a file pointer.
247 error = fgetfdflags(p->p_fd, fd, &tmp);
249 dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0;
253 if (dat->fc_cloexec & FD_CLOEXEC)
254 error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE);
256 error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE);
260 error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd);
267 * Operations on file pointers
269 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
275 dat->fc_flags = OFLAGS(fp->f_flag);
281 nflags = FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS;
282 nflags |= oflags & ~FCNTLFLAGS;
285 if (((nflags ^ oflags) & O_APPEND) && (oflags & FAPPENDONLY))
287 if (error == 0 && ((nflags ^ oflags) & FASYNC)) {
288 tmp = nflags & FASYNC;
289 error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp,
297 error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner,
302 error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner,
308 /* Fall into F_SETLK */
311 if (fp->f_type != DTYPE_VNODE) {
315 vp = (struct vnode *)fp->f_data;
318 * copyin/lockop may block
320 if (dat->fc_flock.l_whence == SEEK_CUR)
321 dat->fc_flock.l_start += fp->f_offset;
323 switch (dat->fc_flock.l_type) {
325 if ((fp->f_flag & FREAD) == 0) {
329 p->p_leader->p_flag |= P_ADVLOCK;
330 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
331 &dat->fc_flock, flg);
334 if ((fp->f_flag & FWRITE) == 0) {
338 p->p_leader->p_flag |= P_ADVLOCK;
339 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
340 &dat->fc_flock, flg);
343 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
344 &dat->fc_flock, F_POSIX);
352 * It is possible to race a close() on the descriptor while
353 * we were blocked getting the lock. If this occurs the
354 * close might not have caught the lock.
356 if (checkfdclosed(p->p_fd, fd, fp)) {
357 dat->fc_flock.l_whence = SEEK_SET;
358 dat->fc_flock.l_start = 0;
359 dat->fc_flock.l_len = 0;
360 dat->fc_flock.l_type = F_UNLCK;
361 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
362 F_UNLCK, &dat->fc_flock, F_POSIX);
367 if (fp->f_type != DTYPE_VNODE) {
371 vp = (struct vnode *)fp->f_data;
373 * copyin/lockop may block
375 if (dat->fc_flock.l_type != F_RDLCK &&
376 dat->fc_flock.l_type != F_WRLCK &&
377 dat->fc_flock.l_type != F_UNLCK) {
381 if (dat->fc_flock.l_whence == SEEK_CUR)
382 dat->fc_flock.l_start += fp->f_offset;
383 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK,
384 &dat->fc_flock, F_POSIX);
397 * The file control system call.
402 sys_fcntl(struct fcntl_args *uap)
409 dat.fc_fd = uap->arg;
412 dat.fc_cloexec = uap->arg;
415 dat.fc_flags = uap->arg;
418 dat.fc_owner = uap->arg;
423 error = copyin((caddr_t)uap->arg, &dat.fc_flock,
424 sizeof(struct flock));
430 error = kern_fcntl(uap->fd, uap->cmd, &dat, curthread->td_ucred);
435 uap->sysmsg_result = dat.fc_fd;
438 uap->sysmsg_result = dat.fc_cloexec;
441 uap->sysmsg_result = dat.fc_flags;
444 uap->sysmsg_result = dat.fc_owner;
446 error = copyout(&dat.fc_flock, (caddr_t)uap->arg,
447 sizeof(struct flock));
456 * Common code for dup, dup2, and fcntl(F_DUPFD).
458 * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells
459 * kern_dup() to destructively dup over an existing file descriptor if new
460 * is already open. DUP_VARIABLE tells kern_dup() to find the lowest
461 * unused file descriptor that is greater than or equal to new.
466 kern_dup(enum dup_type type, int old, int new, int *res)
468 struct thread *td = curthread;
469 struct proc *p = td->td_proc;
470 struct filedesc *fdp = p->p_fd;
479 * Verify that we have a valid descriptor to dup from and
480 * possibly to dup to.
482 * NOTE: maxfilesperuser is not applicable to dup()
485 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
488 dtsize = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
489 if (dtsize > maxfilesperproc)
490 dtsize = maxfilesperproc;
491 if (dtsize < minfilesperproc)
492 dtsize = minfilesperproc;
494 if (new < 0 || new > dtsize)
497 spin_lock_wr(&fdp->fd_spin);
498 if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) {
499 spin_unlock_wr(&fdp->fd_spin);
502 if (type == DUP_FIXED && old == new) {
504 spin_unlock_wr(&fdp->fd_spin);
507 fp = fdp->fd_files[old].fp;
508 oldflags = fdp->fd_files[old].fileflags;
509 fhold(fp); /* MPSAFE - can be called with a spinlock held */
512 * Allocate a new descriptor if DUP_VARIABLE, or expand the table
513 * if the requested descriptor is beyond the current table size.
515 * This can block. Retry if the source descriptor no longer matches
516 * or if our expectation in the expansion case races.
518 * If we are not expanding or allocating a new decriptor, then reset
519 * the target descriptor to a reserved state so we have a uniform
520 * setup for the next code block.
522 if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) {
523 spin_unlock_wr(&fdp->fd_spin);
524 error = fdalloc(p, new, &newfd);
525 spin_lock_wr(&fdp->fd_spin);
527 spin_unlock_wr(&fdp->fd_spin);
534 if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) {
535 fsetfd_locked(fdp, NULL, newfd);
536 spin_unlock_wr(&fdp->fd_spin);
541 * Check for expansion race
543 if (type != DUP_VARIABLE && new != newfd) {
544 fsetfd_locked(fdp, NULL, newfd);
545 spin_unlock_wr(&fdp->fd_spin);
550 * Check for ripout, newfd reused old (this case probably
554 fsetfd_locked(fdp, NULL, newfd);
555 spin_unlock_wr(&fdp->fd_spin);
562 if (fdp->fd_files[new].reserved) {
563 spin_unlock_wr(&fdp->fd_spin);
565 kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new);
566 tsleep(fdp, 0, "fdres", hz);
571 * If the target descriptor was never allocated we have
572 * to allocate it. If it was we have to clean out the
573 * old descriptor. delfp inherits the ref from the
576 delfp = fdp->fd_files[new].fp;
577 fdp->fd_files[new].fp = NULL;
578 fdp->fd_files[new].reserved = 1;
580 fdreserve_locked(fdp, new, 1);
581 if (new > fdp->fd_lastfile)
582 fdp->fd_lastfile = new;
588 * NOTE: still holding an exclusive spinlock
592 * If a descriptor is being overwritten we may hve to tell
593 * fdfree() to sleep to ensure that all relevant process
594 * leaders can be traversed in closef().
596 if (delfp != NULL && p->p_fdtol != NULL) {
597 fdp->fd_holdleaderscount++;
602 KASSERT(delfp == NULL || type == DUP_FIXED,
603 ("dup() picked an open file"));
606 * Duplicate the source descriptor, update lastfile. If the new
607 * descriptor was not allocated and we aren't replacing an existing
608 * descriptor we have to mark the descriptor as being in use.
610 * The fd_files[] array inherits fp's hold reference.
612 fsetfd_locked(fdp, fp, new);
613 fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE;
614 spin_unlock_wr(&fdp->fd_spin);
619 * If we dup'd over a valid file, we now own the reference to it
620 * and must dispose of it using closef() semantics (as if a
621 * close() were performed on it).
624 if (SLIST_FIRST(&delfp->f_klist)) {
626 knote_fdclose(delfp, fdp, new);
631 spin_lock_wr(&fdp->fd_spin);
632 fdp->fd_holdleaderscount--;
633 if (fdp->fd_holdleaderscount == 0 &&
634 fdp->fd_holdleaderswakeup != 0) {
635 fdp->fd_holdleaderswakeup = 0;
636 spin_unlock_wr(&fdp->fd_spin);
637 wakeup(&fdp->fd_holdleaderscount);
639 spin_unlock_wr(&fdp->fd_spin);
647 * If sigio is on the list associated with a process or process group,
648 * disable signalling from the device, remove sigio from the list and
652 funsetown(struct sigio *sigio)
657 *(sigio->sio_myref) = NULL;
659 if (sigio->sio_pgid < 0) {
660 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
662 } else /* if ((*sigiop)->sio_pgid > 0) */ {
663 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
666 crfree(sigio->sio_ucred);
667 kfree(sigio, M_SIGIO);
670 /* Free a list of sigio structures. */
672 funsetownlst(struct sigiolst *sigiolst)
676 while ((sigio = SLIST_FIRST(sigiolst)) != NULL)
681 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
683 * After permission checking, add a sigio structure to the sigio list for
684 * the process or process group.
687 fsetown(pid_t pgid, struct sigio **sigiop)
703 * Policy - Don't allow a process to FSETOWN a process
704 * in another session.
706 * Remove this test to allow maximum flexibility or
707 * restrict FSETOWN to the current process or process
708 * group for maximum safety.
710 if (proc->p_session != curproc->p_session)
714 } else /* if (pgid < 0) */ {
715 pgrp = pgfind(-pgid);
720 * Policy - Don't allow a process to FSETOWN a process
721 * in another session.
723 * Remove this test to allow maximum flexibility or
724 * restrict FSETOWN to the current process or process
725 * group for maximum safety.
727 if (pgrp->pg_session != curproc->p_session)
733 sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK);
735 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
736 sigio->sio_proc = proc;
738 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
739 sigio->sio_pgrp = pgrp;
741 sigio->sio_pgid = pgid;
742 sigio->sio_ucred = crhold(curthread->td_ucred);
743 /* It would be convenient if p_ruid was in ucred. */
744 sigio->sio_ruid = sigio->sio_ucred->cr_ruid;
745 sigio->sio_myref = sigiop;
753 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
756 fgetown(struct sigio *sigio)
758 return (sigio != NULL ? sigio->sio_pgid : 0);
762 * Close many file descriptors.
767 sys_closefrom(struct closefrom_args *uap)
769 return(kern_closefrom(uap->fd));
773 * Close all file descriptors greater then or equal to fd
778 kern_closefrom(int fd)
780 struct thread *td = curthread;
781 struct proc *p = td->td_proc;
782 struct filedesc *fdp;
791 * NOTE: This function will skip unassociated descriptors and
792 * reserved descriptors that have not yet been assigned.
793 * fd_lastfile can change as a side effect of kern_close().
795 spin_lock_wr(&fdp->fd_spin);
796 while (fd <= fdp->fd_lastfile) {
797 if (fdp->fd_files[fd].fp != NULL) {
798 spin_unlock_wr(&fdp->fd_spin);
799 /* ok if this races another close */
800 if (kern_close(fd) == EINTR)
802 spin_lock_wr(&fdp->fd_spin);
806 spin_unlock_wr(&fdp->fd_spin);
811 * Close a file descriptor.
816 sys_close(struct close_args *uap)
818 return(kern_close(uap->fd));
822 * MPALMOSTSAFE - acquires mplock around knote_fdclose() calls
827 struct thread *td = curthread;
828 struct proc *p = td->td_proc;
829 struct filedesc *fdp;
837 spin_lock_wr(&fdp->fd_spin);
838 if ((fp = funsetfd_locked(fdp, fd)) == NULL) {
839 spin_unlock_wr(&fdp->fd_spin);
843 if (p->p_fdtol != NULL) {
845 * Ask fdfree() to sleep to ensure that all relevant
846 * process leaders can be traversed in closef().
848 fdp->fd_holdleaderscount++;
853 * we now hold the fp reference that used to be owned by the descriptor
856 spin_unlock_wr(&fdp->fd_spin);
857 if (SLIST_FIRST(&fp->f_klist)) {
859 knote_fdclose(fp, fdp, fd);
862 error = closef(fp, p);
864 spin_lock_wr(&fdp->fd_spin);
865 fdp->fd_holdleaderscount--;
866 if (fdp->fd_holdleaderscount == 0 &&
867 fdp->fd_holdleaderswakeup != 0) {
868 fdp->fd_holdleaderswakeup = 0;
869 spin_unlock_wr(&fdp->fd_spin);
870 wakeup(&fdp->fd_holdleaderscount);
872 spin_unlock_wr(&fdp->fd_spin);
879 * shutdown_args(int fd, int how)
882 kern_shutdown(int fd, int how)
884 struct thread *td = curthread;
885 struct proc *p = td->td_proc;
891 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
893 error = fo_shutdown(fp, how);
903 sys_shutdown(struct shutdown_args *uap)
908 error = kern_shutdown(uap->s, uap->how);
918 kern_fstat(int fd, struct stat *ub)
920 struct thread *td = curthread;
921 struct proc *p = td->td_proc;
927 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
929 error = fo_stat(fp, ub, td->td_ucred);
936 * Return status information about a file descriptor.
941 sys_fstat(struct fstat_args *uap)
946 error = kern_fstat(uap->fd, &st);
949 error = copyout(&st, uap->sb, sizeof(st));
954 * Return pathconf information about a file descriptor.
959 sys_fpathconf(struct fpathconf_args *uap)
961 struct thread *td = curthread;
962 struct proc *p = td->td_proc;
967 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
970 switch (fp->f_type) {
973 if (uap->name != _PC_PIPE_BUF) {
976 uap->sysmsg_result = PIPE_BUF;
982 vp = (struct vnode *)fp->f_data;
984 error = VOP_PATHCONF(vp, uap->name, &uap->sysmsg_reg);
996 SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand,
1000 * Grow the file table so it can hold through descriptor (want).
1002 * The fdp's spinlock must be held exclusively on entry and may be held
1003 * exclusively on return. The spinlock may be cycled by the routine.
1008 fdgrow_locked(struct filedesc *fdp, int want)
1010 struct fdnode *newfiles;
1011 struct fdnode *oldfiles;
1014 nf = fdp->fd_nfiles;
1016 /* nf has to be of the form 2^n - 1 */
1018 } while (nf <= want);
1020 spin_unlock_wr(&fdp->fd_spin);
1021 newfiles = kmalloc(nf * sizeof(struct fdnode), M_FILEDESC, M_WAITOK);
1022 spin_lock_wr(&fdp->fd_spin);
1025 * We could have raced another extend while we were not holding
1028 if (fdp->fd_nfiles >= nf) {
1029 spin_unlock_wr(&fdp->fd_spin);
1030 kfree(newfiles, M_FILEDESC);
1031 spin_lock_wr(&fdp->fd_spin);
1035 * Copy the existing ofile and ofileflags arrays
1036 * and zero the new portion of each array.
1038 extra = nf - fdp->fd_nfiles;
1039 bcopy(fdp->fd_files, newfiles, fdp->fd_nfiles * sizeof(struct fdnode));
1040 bzero(&newfiles[fdp->fd_nfiles], extra * sizeof(struct fdnode));
1042 oldfiles = fdp->fd_files;
1043 fdp->fd_files = newfiles;
1044 fdp->fd_nfiles = nf;
1046 if (oldfiles != fdp->fd_builtin_files) {
1047 spin_unlock_wr(&fdp->fd_spin);
1048 kfree(oldfiles, M_FILEDESC);
1049 spin_lock_wr(&fdp->fd_spin);
1055 * Number of nodes in right subtree, including the root.
1058 right_subtree_size(int n)
1060 return (n ^ (n | (n + 1)));
1067 right_ancestor(int n)
1069 return (n | (n + 1));
1076 left_ancestor(int n)
1078 return ((n & (n + 1)) - 1);
1082 * Traverse the in-place binary tree buttom-up adjusting the allocation
1083 * count so scans can determine where free descriptors are located.
1085 * MPSAFE - caller must be holding an exclusive spinlock on fdp
1089 fdreserve_locked(struct filedesc *fdp, int fd, int incr)
1092 fdp->fd_files[fd].allocated += incr;
1093 KKASSERT(fdp->fd_files[fd].allocated >= 0);
1094 fd = left_ancestor(fd);
1099 * Reserve a file descriptor for the process. If no error occurs, the
1100 * caller MUST at some point call fsetfd() or assign a file pointer
1101 * or dispose of the reservation.
1106 fdalloc(struct proc *p, int want, int *result)
1108 struct filedesc *fdp = p->p_fd;
1109 struct uidinfo *uip;
1110 int fd, rsize, rsum, node, lim;
1113 * Check dtable size limit
1115 spin_lock_rd(&p->p_limit->p_spin);
1116 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
1119 lim = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
1120 spin_unlock_rd(&p->p_limit->p_spin);
1121 if (lim > maxfilesperproc)
1122 lim = maxfilesperproc;
1123 if (lim < minfilesperproc)
1124 lim = minfilesperproc;
1129 * Check that the user has not run out of descriptors (non-root only).
1130 * As a safety measure the dtable is allowed to have at least
1131 * minfilesperproc open fds regardless of the maxfilesperuser limit.
1133 if (p->p_ucred->cr_uid && fdp->fd_nfiles >= minfilesperproc) {
1134 uip = p->p_ucred->cr_uidinfo;
1135 if (uip->ui_openfiles > maxfilesperuser) {
1136 krateprintf(&krate_uidinfo,
1137 "Warning: user %d pid %d (%s) ran out of "
1138 "file descriptors (%d/%d)\n",
1139 p->p_ucred->cr_uid, (int)p->p_pid,
1141 uip->ui_openfiles, maxfilesperuser);
1147 * Grow the dtable if necessary
1149 spin_lock_wr(&fdp->fd_spin);
1150 if (want >= fdp->fd_nfiles)
1151 fdgrow_locked(fdp, want);
1154 * Search for a free descriptor starting at the higher
1155 * of want or fd_freefile. If that fails, consider
1156 * expanding the ofile array.
1158 * NOTE! the 'allocated' field is a cumulative recursive allocation
1159 * count. If we happen to see a value of 0 then we can shortcut
1160 * our search. Otherwise we run through through the tree going
1161 * down branches we know have free descriptor(s) until we hit a
1162 * leaf node. The leaf node will be free but will not necessarily
1163 * have an allocated field of 0.
1166 /* move up the tree looking for a subtree with a free node */
1167 for (fd = max(want, fdp->fd_freefile); fd < min(fdp->fd_nfiles, lim);
1168 fd = right_ancestor(fd)) {
1169 if (fdp->fd_files[fd].allocated == 0)
1172 rsize = right_subtree_size(fd);
1173 if (fdp->fd_files[fd].allocated == rsize)
1174 continue; /* right subtree full */
1177 * Free fd is in the right subtree of the tree rooted at fd.
1178 * Call that subtree R. Look for the smallest (leftmost)
1179 * subtree of R with an unallocated fd: continue moving
1180 * down the left branch until encountering a full left
1181 * subtree, then move to the right.
1183 for (rsum = 0, rsize /= 2; rsize > 0; rsize /= 2) {
1185 rsum += fdp->fd_files[node].allocated;
1186 if (fdp->fd_files[fd].allocated == rsum + rsize) {
1187 fd = node; /* move to the right */
1188 if (fdp->fd_files[node].allocated == 0)
1197 * No space in current array. Expand?
1199 if (fdp->fd_nfiles >= lim) {
1200 spin_unlock_wr(&fdp->fd_spin);
1203 fdgrow_locked(fdp, want);
1207 KKASSERT(fd < fdp->fd_nfiles);
1208 if (fd > fdp->fd_lastfile)
1209 fdp->fd_lastfile = fd;
1210 if (want <= fdp->fd_freefile)
1211 fdp->fd_freefile = fd;
1213 KKASSERT(fdp->fd_files[fd].fp == NULL);
1214 KKASSERT(fdp->fd_files[fd].reserved == 0);
1215 fdp->fd_files[fd].fileflags = 0;
1216 fdp->fd_files[fd].reserved = 1;
1217 fdreserve_locked(fdp, fd, 1);
1218 spin_unlock_wr(&fdp->fd_spin);
1223 * Check to see whether n user file descriptors
1224 * are available to the process p.
1229 fdavail(struct proc *p, int n)
1231 struct filedesc *fdp = p->p_fd;
1232 struct fdnode *fdnode;
1235 spin_lock_rd(&p->p_limit->p_spin);
1236 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
1239 lim = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
1240 spin_unlock_rd(&p->p_limit->p_spin);
1241 if (lim > maxfilesperproc)
1242 lim = maxfilesperproc;
1243 if (lim < minfilesperproc)
1244 lim = minfilesperproc;
1246 spin_lock_rd(&fdp->fd_spin);
1247 if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) {
1248 spin_unlock_rd(&fdp->fd_spin);
1251 last = min(fdp->fd_nfiles, lim);
1252 fdnode = &fdp->fd_files[fdp->fd_freefile];
1253 for (i = last - fdp->fd_freefile; --i >= 0; ++fdnode) {
1254 if (fdnode->fp == NULL && --n <= 0) {
1255 spin_unlock_rd(&fdp->fd_spin);
1259 spin_unlock_rd(&fdp->fd_spin);
1264 * Revoke open descriptors referencing (f_data, f_type)
1266 * Any revoke executed within a prison is only able to
1267 * revoke descriptors for processes within that prison.
1269 * Returns 0 on success or an error code.
1271 struct fdrevoke_info {
1281 static int fdrevoke_check_callback(struct file *fp, void *vinfo);
1282 static int fdrevoke_proc_callback(struct proc *p, void *vinfo);
1285 fdrevoke(void *f_data, short f_type, struct ucred *cred)
1287 struct fdrevoke_info info;
1290 bzero(&info, sizeof(info));
1294 error = falloc(NULL, &info.nfp, NULL);
1299 * Scan the file pointer table once. dups do not dup file pointers,
1300 * only descriptors, so there is no leak. Set FREVOKED on the fps
1303 allfiles_scan_exclusive(fdrevoke_check_callback, &info);
1306 * If any fps were marked track down the related descriptors
1307 * and close them. Any dup()s at this point will notice
1308 * the FREVOKED already set in the fp and do the right thing.
1310 * Any fps with non-zero msgcounts (aka sent over a unix-domain
1311 * socket) bumped the intransit counter and will require a
1312 * scan. Races against fps leaving the socket are closed by
1313 * the socket code checking for FREVOKED.
1316 allproc_scan(fdrevoke_proc_callback, &info);
1318 unp_revoke_gc(info.nfp);
1324 * Locate matching file pointers directly.
1327 fdrevoke_check_callback(struct file *fp, void *vinfo)
1329 struct fdrevoke_info *info = vinfo;
1332 * File pointers already flagged for revokation are skipped.
1334 if (fp->f_flag & FREVOKED)
1338 * If revoking from a prison file pointers created outside of
1339 * that prison, or file pointers without creds, cannot be revoked.
1341 if (info->cred->cr_prison &&
1342 (fp->f_cred == NULL ||
1343 info->cred->cr_prison != fp->f_cred->cr_prison)) {
1348 * If the file pointer matches then mark it for revocation. The
1349 * flag is currently only used by unp_revoke_gc().
1351 * info->count is a heuristic and can race in a SMP environment.
1353 if (info->data == fp->f_data && info->type == fp->f_type) {
1354 atomic_set_int(&fp->f_flag, FREVOKED);
1355 info->count += fp->f_count;
1363 * Locate matching file pointers via process descriptor tables.
1366 fdrevoke_proc_callback(struct proc *p, void *vinfo)
1368 struct fdrevoke_info *info = vinfo;
1369 struct filedesc *fdp;
1373 if (p->p_stat == SIDL || p->p_stat == SZOMB)
1375 if (info->cred->cr_prison &&
1376 info->cred->cr_prison != p->p_ucred->cr_prison) {
1381 * If the controlling terminal of the process matches the
1382 * vnode being revoked we clear the controlling terminal.
1384 * The normal spec_close() may not catch this because it
1385 * uses curproc instead of p.
1387 if (p->p_session && info->type == DTYPE_VNODE &&
1388 info->data == p->p_session->s_ttyvp) {
1389 p->p_session->s_ttyvp = NULL;
1394 * Softref the fdp to prevent it from being destroyed
1396 spin_lock_wr(&p->p_spin);
1397 if ((fdp = p->p_fd) == NULL) {
1398 spin_unlock_wr(&p->p_spin);
1401 atomic_add_int(&fdp->fd_softrefs, 1);
1402 spin_unlock_wr(&p->p_spin);
1405 * Locate and close any matching file descriptors.
1407 spin_lock_wr(&fdp->fd_spin);
1408 for (n = 0; n < fdp->fd_nfiles; ++n) {
1409 if ((fp = fdp->fd_files[n].fp) == NULL)
1411 if (fp->f_flag & FREVOKED) {
1413 fdp->fd_files[n].fp = info->nfp;
1414 spin_unlock_wr(&fdp->fd_spin);
1415 knote_fdclose(fp, fdp, n); /* XXX */
1417 spin_lock_wr(&fdp->fd_spin);
1421 spin_unlock_wr(&fdp->fd_spin);
1422 atomic_subtract_int(&fdp->fd_softrefs, 1);
1428 * Create a new open file structure and reserve a file decriptor
1429 * for the process that refers to it.
1431 * Root creds are checked using lp, or assumed if lp is NULL. If
1432 * resultfd is non-NULL then lp must also be non-NULL. No file
1433 * descriptor is reserved (and no process context is needed) if
1436 * A file pointer with a refcount of 1 is returned. Note that the
1437 * file pointer is NOT associated with the descriptor. If falloc
1438 * returns success, fsetfd() MUST be called to either associate the
1439 * file pointer or clear the reservation.
1444 falloc(struct lwp *lp, struct file **resultfp, int *resultfd)
1446 static struct timeval lastfail;
1449 struct ucred *cred = lp ? lp->lwp_thread->td_ucred : proc0.p_ucred;
1455 * Handle filetable full issues and root overfill.
1457 if (nfiles >= maxfiles - maxfilesrootres &&
1458 (cred->cr_ruid != 0 || nfiles >= maxfiles)) {
1459 if (ppsratecheck(&lastfail, &curfail, 1)) {
1460 kprintf("kern.maxfiles limit exceeded by uid %d, "
1461 "please see tuning(7).\n",
1469 * Allocate a new file descriptor.
1471 fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO);
1472 spin_init(&fp->f_spin);
1473 SLIST_INIT(&fp->f_klist);
1475 fp->f_ops = &badfileops;
1478 spin_lock_wr(&filehead_spin);
1480 LIST_INSERT_HEAD(&filehead, fp, f_list);
1481 spin_unlock_wr(&filehead_spin);
1483 if ((error = fdalloc(lp->lwp_proc, 0, resultfd)) != 0) {
1496 * Check for races against a file descriptor by determining that the
1497 * file pointer is still associated with the specified file descriptor,
1498 * and a close is not currently in progress.
1503 checkfdclosed(struct filedesc *fdp, int fd, struct file *fp)
1507 spin_lock_rd(&fdp->fd_spin);
1508 if ((unsigned)fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp)
1512 spin_unlock_rd(&fdp->fd_spin);
1517 * Associate a file pointer with a previously reserved file descriptor.
1518 * This function always succeeds.
1520 * If fp is NULL, the file descriptor is returned to the pool.
1524 * MPSAFE (exclusive spinlock must be held on call)
1527 fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd)
1529 KKASSERT((unsigned)fd < fdp->fd_nfiles);
1530 KKASSERT(fdp->fd_files[fd].reserved != 0);
1533 fdp->fd_files[fd].fp = fp;
1534 fdp->fd_files[fd].reserved = 0;
1536 fdp->fd_files[fd].reserved = 0;
1537 fdreserve_locked(fdp, fd, -1);
1538 fdfixup_locked(fdp, fd);
1546 fsetfd(struct filedesc *fdp, struct file *fp, int fd)
1548 spin_lock_wr(&fdp->fd_spin);
1549 fsetfd_locked(fdp, fp, fd);
1550 spin_unlock_wr(&fdp->fd_spin);
1554 * MPSAFE (exclusive spinlock must be held on call)
1558 funsetfd_locked(struct filedesc *fdp, int fd)
1562 if ((unsigned)fd >= fdp->fd_nfiles)
1564 if ((fp = fdp->fd_files[fd].fp) == NULL)
1566 fdp->fd_files[fd].fp = NULL;
1567 fdp->fd_files[fd].fileflags = 0;
1569 fdreserve_locked(fdp, fd, -1);
1570 fdfixup_locked(fdp, fd);
1578 fgetfdflags(struct filedesc *fdp, int fd, int *flagsp)
1582 spin_lock_rd(&fdp->fd_spin);
1583 if (((u_int)fd) >= fdp->fd_nfiles) {
1585 } else if (fdp->fd_files[fd].fp == NULL) {
1588 *flagsp = fdp->fd_files[fd].fileflags;
1591 spin_unlock_rd(&fdp->fd_spin);
1599 fsetfdflags(struct filedesc *fdp, int fd, int add_flags)
1603 spin_lock_wr(&fdp->fd_spin);
1604 if (((u_int)fd) >= fdp->fd_nfiles) {
1606 } else if (fdp->fd_files[fd].fp == NULL) {
1609 fdp->fd_files[fd].fileflags |= add_flags;
1612 spin_unlock_wr(&fdp->fd_spin);
1620 fclrfdflags(struct filedesc *fdp, int fd, int rem_flags)
1624 spin_lock_wr(&fdp->fd_spin);
1625 if (((u_int)fd) >= fdp->fd_nfiles) {
1627 } else if (fdp->fd_files[fd].fp == NULL) {
1630 fdp->fd_files[fd].fileflags &= ~rem_flags;
1633 spin_unlock_wr(&fdp->fd_spin);
1638 * Set/Change/Clear the creds for a fp and synchronize the uidinfo.
1641 fsetcred(struct file *fp, struct ucred *ncr)
1644 struct uidinfo *uip;
1647 if (ocr == NULL || ncr == NULL || ocr->cr_uidinfo != ncr->cr_uidinfo) {
1649 uip = ocr->cr_uidinfo;
1650 atomic_add_int(&uip->ui_openfiles, -1);
1653 uip = ncr->cr_uidinfo;
1654 atomic_add_int(&uip->ui_openfiles, 1);
1665 * Free a file descriptor.
1669 ffree(struct file *fp)
1671 KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!"));
1672 spin_lock_wr(&filehead_spin);
1673 LIST_REMOVE(fp, f_list);
1675 spin_unlock_wr(&filehead_spin);
1677 if (fp->f_nchandle.ncp)
1678 cache_drop(&fp->f_nchandle);
1683 * called from init_main, initialize filedesc0 for proc0.
1686 fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask)
1690 fdp0->fd_refcnt = 1;
1691 fdp0->fd_cmask = cmask;
1692 fdp0->fd_files = fdp0->fd_builtin_files;
1693 fdp0->fd_nfiles = NDFILE;
1694 fdp0->fd_lastfile = -1;
1695 spin_init(&fdp0->fd_spin);
1699 * Build a new filedesc structure.
1704 fdinit(struct proc *p)
1706 struct filedesc *newfdp;
1707 struct filedesc *fdp = p->p_fd;
1709 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO);
1710 spin_lock_rd(&fdp->fd_spin);
1712 newfdp->fd_cdir = fdp->fd_cdir;
1713 vref(newfdp->fd_cdir);
1714 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1718 * rdir may not be set in e.g. proc0 or anything vm_fork'd off of
1719 * proc0, but should unconditionally exist in other processes.
1722 newfdp->fd_rdir = fdp->fd_rdir;
1723 vref(newfdp->fd_rdir);
1724 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1727 newfdp->fd_jdir = fdp->fd_jdir;
1728 vref(newfdp->fd_jdir);
1729 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1731 spin_unlock_rd(&fdp->fd_spin);
1733 /* Create the file descriptor table. */
1734 newfdp->fd_refcnt = 1;
1735 newfdp->fd_cmask = cmask;
1736 newfdp->fd_files = newfdp->fd_builtin_files;
1737 newfdp->fd_nfiles = NDFILE;
1738 newfdp->fd_lastfile = -1;
1739 spin_init(&newfdp->fd_spin);
1745 * Share a filedesc structure.
1750 fdshare(struct proc *p)
1752 struct filedesc *fdp;
1755 spin_lock_wr(&fdp->fd_spin);
1757 spin_unlock_wr(&fdp->fd_spin);
1762 * Copy a filedesc structure.
1767 fdcopy(struct proc *p)
1769 struct filedesc *fdp = p->p_fd;
1770 struct filedesc *newfdp;
1771 struct fdnode *fdnode;
1776 * Certain daemons might not have file descriptors.
1782 * Allocate the new filedesc and fd_files[] array. This can race
1783 * with operations by other threads on the fdp so we have to be
1786 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO);
1788 spin_lock_rd(&fdp->fd_spin);
1789 if (fdp->fd_lastfile < NDFILE) {
1790 newfdp->fd_files = newfdp->fd_builtin_files;
1794 * We have to allocate (N^2-1) entries for our in-place
1795 * binary tree. Allow the table to shrink.
1799 while (ni > fdp->fd_lastfile && ni > NDFILE) {
1803 spin_unlock_rd(&fdp->fd_spin);
1804 newfdp->fd_files = kmalloc(i * sizeof(struct fdnode),
1805 M_FILEDESC, M_WAITOK | M_ZERO);
1808 * Check for race, retry
1810 spin_lock_rd(&fdp->fd_spin);
1811 if (i <= fdp->fd_lastfile) {
1812 spin_unlock_rd(&fdp->fd_spin);
1813 kfree(newfdp->fd_files, M_FILEDESC);
1819 * Dup the remaining fields. vref() and cache_hold() can be
1820 * safely called while holding the read spinlock on fdp.
1822 * The read spinlock on fdp is still being held.
1824 * NOTE: vref and cache_hold calls for the case where the vnode
1825 * or cache entry already has at least one ref may be called
1826 * while holding spin locks.
1828 if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) {
1829 vref(newfdp->fd_cdir);
1830 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1833 * We must check for fd_rdir here, at least for now because
1834 * the init process is created before we have access to the
1835 * rootvode to take a reference to it.
1837 if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) {
1838 vref(newfdp->fd_rdir);
1839 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1841 if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) {
1842 vref(newfdp->fd_jdir);
1843 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1845 newfdp->fd_refcnt = 1;
1846 newfdp->fd_nfiles = i;
1847 newfdp->fd_lastfile = fdp->fd_lastfile;
1848 newfdp->fd_freefile = fdp->fd_freefile;
1849 newfdp->fd_cmask = fdp->fd_cmask;
1850 spin_init(&newfdp->fd_spin);
1853 * Copy the descriptor table through (i). This also copies the
1854 * allocation state. Then go through and ref the file pointers
1855 * and clean up any KQ descriptors.
1857 * kq descriptors cannot be copied. Since we haven't ref'd the
1858 * copied files yet we can ignore the return value from funsetfd().
1860 * The read spinlock on fdp is still being held.
1862 bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode));
1863 for (i = 0 ; i < newfdp->fd_nfiles; ++i) {
1864 fdnode = &newfdp->fd_files[i];
1865 if (fdnode->reserved) {
1866 fdreserve_locked(newfdp, i, -1);
1867 fdnode->reserved = 0;
1868 fdfixup_locked(newfdp, i);
1869 } else if (fdnode->fp) {
1870 if (fdnode->fp->f_type == DTYPE_KQUEUE) {
1871 (void)funsetfd_locked(newfdp, i);
1877 spin_unlock_rd(&fdp->fd_spin);
1882 * Release a filedesc structure.
1884 * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE)
1887 fdfree(struct proc *p, struct filedesc *repl)
1889 struct filedesc *fdp;
1890 struct fdnode *fdnode;
1892 struct filedesc_to_leader *fdtol;
1898 * Certain daemons might not have file descriptors.
1907 * Severe messing around to follow.
1909 spin_lock_wr(&fdp->fd_spin);
1911 /* Check for special need to clear POSIX style locks */
1913 if (fdtol != NULL) {
1914 KASSERT(fdtol->fdl_refcount > 0,
1915 ("filedesc_to_refcount botch: fdl_refcount=%d",
1916 fdtol->fdl_refcount));
1917 if (fdtol->fdl_refcount == 1 &&
1918 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1919 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1920 fdnode = &fdp->fd_files[i];
1921 if (fdnode->fp == NULL ||
1922 fdnode->fp->f_type != DTYPE_VNODE) {
1927 spin_unlock_wr(&fdp->fd_spin);
1929 lf.l_whence = SEEK_SET;
1932 lf.l_type = F_UNLCK;
1933 vp = (struct vnode *)fp->f_data;
1934 (void) VOP_ADVLOCK(vp,
1935 (caddr_t)p->p_leader,
1940 spin_lock_wr(&fdp->fd_spin);
1944 if (fdtol->fdl_refcount == 1) {
1945 if (fdp->fd_holdleaderscount > 0 &&
1946 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1948 * close() or do_dup() has cleared a reference
1949 * in a shared file descriptor table.
1951 fdp->fd_holdleaderswakeup = 1;
1952 ssleep(&fdp->fd_holdleaderscount,
1953 &fdp->fd_spin, 0, "fdlhold", 0);
1956 if (fdtol->fdl_holdcount > 0) {
1958 * Ensure that fdtol->fdl_leader
1959 * remains valid in closef().
1961 fdtol->fdl_wakeup = 1;
1962 ssleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0);
1966 fdtol->fdl_refcount--;
1967 if (fdtol->fdl_refcount == 0 &&
1968 fdtol->fdl_holdcount == 0) {
1969 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev;
1970 fdtol->fdl_prev->fdl_next = fdtol->fdl_next;
1975 if (fdtol != NULL) {
1976 spin_unlock_wr(&fdp->fd_spin);
1977 kfree(fdtol, M_FILEDESC_TO_LEADER);
1978 spin_lock_wr(&fdp->fd_spin);
1981 if (--fdp->fd_refcnt > 0) {
1982 spin_unlock_wr(&fdp->fd_spin);
1983 spin_lock_wr(&p->p_spin);
1985 spin_unlock_wr(&p->p_spin);
1990 * Even though we are the last reference to the structure allproc
1991 * scans may still reference the structure. Maintain proper
1992 * locks until we can replace p->p_fd.
1994 * Also note that kqueue's closef still needs to reference the
1995 * fdp via p->p_fd, so we have to close the descriptors before
1996 * we replace p->p_fd.
1998 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1999 if (fdp->fd_files[i].fp) {
2000 fp = funsetfd_locked(fdp, i);
2002 spin_unlock_wr(&fdp->fd_spin);
2003 if (SLIST_FIRST(&fp->f_klist)) {
2005 knote_fdclose(fp, fdp, i);
2009 spin_lock_wr(&fdp->fd_spin);
2013 spin_unlock_wr(&fdp->fd_spin);
2016 * Interlock against an allproc scan operations (typically frevoke).
2018 spin_lock_wr(&p->p_spin);
2020 spin_unlock_wr(&p->p_spin);
2023 * Wait for any softrefs to go away. This race rarely occurs so
2024 * we can use a non-critical-path style poll/sleep loop. The
2025 * race only occurs against allproc scans.
2027 * No new softrefs can occur with the fdp disconnected from the
2030 if (fdp->fd_softrefs) {
2031 kprintf("pid %d: Warning, fdp race avoided\n", p->p_pid);
2032 while (fdp->fd_softrefs)
2033 tsleep(&fdp->fd_softrefs, 0, "fdsoft", 1);
2036 if (fdp->fd_files != fdp->fd_builtin_files)
2037 kfree(fdp->fd_files, M_FILEDESC);
2039 cache_drop(&fdp->fd_ncdir);
2040 vrele(fdp->fd_cdir);
2043 cache_drop(&fdp->fd_nrdir);
2044 vrele(fdp->fd_rdir);
2047 cache_drop(&fdp->fd_njdir);
2048 vrele(fdp->fd_jdir);
2050 kfree(fdp, M_FILEDESC);
2054 * Retrieve and reference the file pointer associated with a descriptor.
2059 holdfp(struct filedesc *fdp, int fd, int flag)
2063 spin_lock_rd(&fdp->fd_spin);
2064 if (((u_int)fd) >= fdp->fd_nfiles) {
2068 if ((fp = fdp->fd_files[fd].fp) == NULL)
2070 if ((fp->f_flag & flag) == 0 && flag != -1) {
2076 spin_unlock_rd(&fdp->fd_spin);
2081 * holdsock() - load the struct file pointer associated
2082 * with a socket into *fpp. If an error occurs, non-zero
2083 * will be returned and *fpp will be set to NULL.
2088 holdsock(struct filedesc *fdp, int fd, struct file **fpp)
2093 spin_lock_rd(&fdp->fd_spin);
2094 if ((unsigned)fd >= fdp->fd_nfiles) {
2099 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2103 if (fp->f_type != DTYPE_SOCKET) {
2110 spin_unlock_rd(&fdp->fd_spin);
2116 * Convert a user file descriptor to a held file pointer.
2121 holdvnode(struct filedesc *fdp, int fd, struct file **fpp)
2126 spin_lock_rd(&fdp->fd_spin);
2127 if ((unsigned)fd >= fdp->fd_nfiles) {
2132 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2136 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) {
2144 spin_unlock_rd(&fdp->fd_spin);
2150 * For setugid programs, we don't want to people to use that setugidness
2151 * to generate error messages which write to a file which otherwise would
2152 * otherwise be off-limits to the process.
2154 * This is a gross hack to plug the hole. A better solution would involve
2155 * a special vop or other form of generalized access control mechanism. We
2156 * go ahead and just reject all procfs file systems accesses as dangerous.
2158 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is
2159 * sufficient. We also don't for check setugidness since we know we are.
2162 is_unsafe(struct file *fp)
2164 if (fp->f_type == DTYPE_VNODE &&
2165 ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS)
2171 * Make this setguid thing safe, if at all possible.
2173 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2176 setugidsafety(struct proc *p)
2178 struct filedesc *fdp = p->p_fd;
2181 /* Certain daemons might not have file descriptors. */
2186 * note: fdp->fd_files may be reallocated out from under us while
2187 * we are blocked in a close. Be careful!
2189 for (i = 0; i <= fdp->fd_lastfile; i++) {
2192 if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) {
2196 * NULL-out descriptor prior to close to avoid
2197 * a race while close blocks.
2199 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2200 knote_fdclose(fp, fdp, i);
2208 * Close any files on exec?
2210 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2213 fdcloseexec(struct proc *p)
2215 struct filedesc *fdp = p->p_fd;
2218 /* Certain daemons might not have file descriptors. */
2223 * We cannot cache fd_files since operations may block and rip
2224 * them out from under us.
2226 for (i = 0; i <= fdp->fd_lastfile; i++) {
2227 if (fdp->fd_files[i].fp != NULL &&
2228 (fdp->fd_files[i].fileflags & UF_EXCLOSE)) {
2232 * NULL-out descriptor prior to close to avoid
2233 * a race while close blocks.
2235 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2236 knote_fdclose(fp, fdp, i);
2244 * It is unsafe for set[ug]id processes to be started with file
2245 * descriptors 0..2 closed, as these descriptors are given implicit
2246 * significance in the Standard C library. fdcheckstd() will create a
2247 * descriptor referencing /dev/null for each of stdin, stdout, and
2248 * stderr that is not already open.
2250 * NOT MPSAFE - calls falloc, vn_open, etc
2253 fdcheckstd(struct lwp *lp)
2255 struct nlookupdata nd;
2256 struct filedesc *fdp;
2259 int i, error, flags, devnull;
2261 fdp = lp->lwp_proc->p_fd;
2266 for (i = 0; i < 3; i++) {
2267 if (fdp->fd_files[i].fp != NULL)
2270 if ((error = falloc(lp, &fp, &devnull)) != 0)
2273 error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE,
2274 NLC_FOLLOW|NLC_LOCKVP);
2275 flags = FREAD | FWRITE;
2277 error = vn_open(&nd, fp, flags, 0);
2279 fsetfd(fdp, fp, devnull);
2281 fsetfd(fdp, NULL, devnull);
2286 KKASSERT(i == devnull);
2288 error = kern_dup(DUP_FIXED, devnull, i, &retval);
2297 * Internal form of close.
2298 * Decrement reference count on file structure.
2299 * Note: td and/or p may be NULL when closing a file
2300 * that was being passed in a message.
2302 * MPALMOSTSAFE - acquires mplock for VOP operations
2305 closef(struct file *fp, struct proc *p)
2309 struct filedesc_to_leader *fdtol;
2315 * POSIX record locking dictates that any close releases ALL
2316 * locks owned by this process. This is handled by setting
2317 * a flag in the unlock to free ONLY locks obeying POSIX
2318 * semantics, and not to free BSD-style file locks.
2319 * If the descriptor was in a message, POSIX-style locks
2320 * aren't passed with the descriptor.
2322 if (p != NULL && fp->f_type == DTYPE_VNODE &&
2323 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2326 if ((p->p_leader->p_flag & P_ADVLOCK) != 0) {
2327 lf.l_whence = SEEK_SET;
2330 lf.l_type = F_UNLCK;
2331 vp = (struct vnode *)fp->f_data;
2332 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
2336 if (fdtol != NULL) {
2338 * Handle special case where file descriptor table
2339 * is shared between multiple process leaders.
2341 for (fdtol = fdtol->fdl_next;
2342 fdtol != p->p_fdtol;
2343 fdtol = fdtol->fdl_next) {
2344 if ((fdtol->fdl_leader->p_flag &
2347 fdtol->fdl_holdcount++;
2348 lf.l_whence = SEEK_SET;
2351 lf.l_type = F_UNLCK;
2352 vp = (struct vnode *)fp->f_data;
2353 (void) VOP_ADVLOCK(vp,
2354 (caddr_t)fdtol->fdl_leader,
2355 F_UNLCK, &lf, F_POSIX);
2356 fdtol->fdl_holdcount--;
2357 if (fdtol->fdl_holdcount == 0 &&
2358 fdtol->fdl_wakeup != 0) {
2359 fdtol->fdl_wakeup = 0;
2372 * fhold() can only be called if f_count is already at least 1 (i.e. the
2373 * caller of fhold() already has a reference to the file pointer in some
2376 * f_count is not spin-locked. Instead, atomic ops are used for
2377 * incrementing, decrementing, and handling the 1->0 transition.
2380 fhold(struct file *fp)
2382 atomic_add_int(&fp->f_count, 1);
2386 * fdrop() - drop a reference to a descriptor
2388 * MPALMOSTSAFE - acquires mplock for final close sequence
2391 fdrop(struct file *fp)
2398 * A combined fetch and subtract is needed to properly detect
2399 * 1->0 transitions, otherwise two cpus dropping from a ref
2400 * count of 2 might both try to run the 1->0 code.
2402 if (atomic_fetchadd_int(&fp->f_count, -1) > 1)
2405 KKASSERT(SLIST_FIRST(&fp->f_klist) == NULL);
2409 * The last reference has gone away, we own the fp structure free
2412 if (fp->f_count < 0)
2413 panic("fdrop: count < 0");
2414 if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE &&
2415 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2417 lf.l_whence = SEEK_SET;
2420 lf.l_type = F_UNLCK;
2421 vp = (struct vnode *)fp->f_data;
2422 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2424 if (fp->f_ops != &badfileops)
2425 error = fo_close(fp);
2434 * Apply an advisory lock on a file descriptor.
2436 * Just attempt to get a record lock of the requested type on
2437 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
2442 sys_flock(struct flock_args *uap)
2444 struct proc *p = curproc;
2450 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
2453 if (fp->f_type != DTYPE_VNODE) {
2457 vp = (struct vnode *)fp->f_data;
2458 lf.l_whence = SEEK_SET;
2461 if (uap->how & LOCK_UN) {
2462 lf.l_type = F_UNLCK;
2463 fp->f_flag &= ~FHASLOCK;
2464 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2467 if (uap->how & LOCK_EX)
2468 lf.l_type = F_WRLCK;
2469 else if (uap->how & LOCK_SH)
2470 lf.l_type = F_RDLCK;
2475 fp->f_flag |= FHASLOCK;
2476 if (uap->how & LOCK_NB)
2477 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0);
2479 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT);
2487 * File Descriptor pseudo-device driver (/dev/fd/).
2489 * Opening minor device N dup()s the file (if any) connected to file
2490 * descriptor N belonging to the calling process. Note that this driver
2491 * consists of only the ``open()'' routine, because all subsequent
2492 * references to this file will be direct to the other driver.
2495 fdopen(struct dev_open_args *ap)
2497 thread_t td = curthread;
2499 KKASSERT(td->td_lwp != NULL);
2502 * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the
2503 * the file descriptor being sought for duplication. The error
2504 * return ensures that the vnode for this device will be released
2505 * by vn_open. Open will detect this special error and take the
2506 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
2507 * will simply report the error.
2509 td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev);
2514 * The caller has reserved the file descriptor dfd for us. On success we
2515 * must fsetfd() it. On failure the caller will clean it up.
2520 dupfdopen(struct filedesc *fdp, int dfd, int sfd, int mode, int error)
2526 if ((wfp = holdfp(fdp, sfd, -1)) == NULL)
2530 * Close a revoke/dup race. Duping a descriptor marked as revoked
2531 * will dup a dummy descriptor instead of the real one.
2533 if (wfp->f_flag & FREVOKED) {
2534 kprintf("Warning: attempt to dup() a revoked descriptor\n");
2537 werror = falloc(NULL, &wfp, NULL);
2543 * There are two cases of interest here.
2545 * For ENODEV simply dup sfd to file descriptor dfd and return.
2547 * For ENXIO steal away the file structure from sfd and store it
2548 * dfd. sfd is effectively closed by this operation.
2550 * Any other error code is just returned.
2555 * Check that the mode the file is being opened for is a
2556 * subset of the mode of the existing descriptor.
2558 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
2562 spin_lock_wr(&fdp->fd_spin);
2563 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2564 fsetfd_locked(fdp, wfp, dfd);
2565 spin_unlock_wr(&fdp->fd_spin);
2570 * Steal away the file pointer from dfd, and stuff it into indx.
2572 spin_lock_wr(&fdp->fd_spin);
2573 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2574 fsetfd(fdp, wfp, dfd);
2575 if ((xfp = funsetfd_locked(fdp, sfd)) != NULL) {
2576 spin_unlock_wr(&fdp->fd_spin);
2579 spin_unlock_wr(&fdp->fd_spin);
2591 * NOT MPSAFE - I think these refer to a common file descriptor table
2592 * and we need to spinlock that to link fdtol in.
2594 struct filedesc_to_leader *
2595 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
2596 struct proc *leader)
2598 struct filedesc_to_leader *fdtol;
2600 fdtol = kmalloc(sizeof(struct filedesc_to_leader),
2601 M_FILEDESC_TO_LEADER, M_WAITOK);
2602 fdtol->fdl_refcount = 1;
2603 fdtol->fdl_holdcount = 0;
2604 fdtol->fdl_wakeup = 0;
2605 fdtol->fdl_leader = leader;
2607 fdtol->fdl_next = old->fdl_next;
2608 fdtol->fdl_prev = old;
2609 old->fdl_next = fdtol;
2610 fdtol->fdl_next->fdl_prev = fdtol;
2612 fdtol->fdl_next = fdtol;
2613 fdtol->fdl_prev = fdtol;
2619 * Scan all file pointers in the system. The callback is made with
2620 * the master list spinlock held exclusively.
2625 allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data)
2630 spin_lock_wr(&filehead_spin);
2631 LIST_FOREACH(fp, &filehead, f_list) {
2632 res = callback(fp, data);
2636 spin_unlock_wr(&filehead_spin);
2640 * Get file structures.
2642 * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe)
2645 struct sysctl_kern_file_info {
2648 struct sysctl_req *req;
2651 static int sysctl_kern_file_callback(struct proc *p, void *data);
2654 sysctl_kern_file(SYSCTL_HANDLER_ARGS)
2656 struct sysctl_kern_file_info info;
2659 * Note: because the number of file descriptors is calculated
2660 * in different ways for sizing vs returning the data,
2661 * there is information leakage from the first loop. However,
2662 * it is of a similar order of magnitude to the leakage from
2663 * global system statistics such as kern.openfiles.
2665 * When just doing a count, note that we cannot just count
2666 * the elements and add f_count via the filehead list because
2667 * threaded processes share their descriptor table and f_count might
2668 * still be '1' in that case.
2670 * Since the SYSCTL op can block, we must hold the process to
2671 * prevent it being ripped out from under us either in the
2672 * file descriptor loop or in the greater LIST_FOREACH. The
2673 * process may be in varying states of disrepair. If the process
2674 * is in SZOMB we may have caught it just as it is being removed
2675 * from the allproc list, we must skip it in that case to maintain
2676 * an unbroken chain through the allproc list.
2681 allproc_scan(sysctl_kern_file_callback, &info);
2684 * When just calculating the size, overestimate a bit to try to
2685 * prevent system activity from causing the buffer-fill call
2688 if (req->oldptr == NULL) {
2689 info.count = (info.count + 16) + (info.count / 10);
2690 info.error = SYSCTL_OUT(req, NULL,
2691 info.count * sizeof(struct kinfo_file));
2693 return (info.error);
2697 sysctl_kern_file_callback(struct proc *p, void *data)
2699 struct sysctl_kern_file_info *info = data;
2700 struct kinfo_file kf;
2701 struct filedesc *fdp;
2706 if (p->p_stat == SIDL || p->p_stat == SZOMB)
2708 if (!PRISON_CHECK(info->req->td->td_ucred, p->p_ucred) != 0)
2712 * Softref the fdp to prevent it from being destroyed
2714 spin_lock_wr(&p->p_spin);
2715 if ((fdp = p->p_fd) == NULL) {
2716 spin_unlock_wr(&p->p_spin);
2719 atomic_add_int(&fdp->fd_softrefs, 1);
2720 spin_unlock_wr(&p->p_spin);
2723 * The fdp's own spinlock prevents the contents from being
2726 spin_lock_rd(&fdp->fd_spin);
2727 for (n = 0; n < fdp->fd_nfiles; ++n) {
2728 if ((fp = fdp->fd_files[n].fp) == NULL)
2730 if (info->req->oldptr == NULL) {
2733 uid = p->p_ucred ? p->p_ucred->cr_uid : -1;
2734 kcore_make_file(&kf, fp, p->p_pid, uid, n);
2735 spin_unlock_rd(&fdp->fd_spin);
2736 info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf));
2737 spin_lock_rd(&fdp->fd_spin);
2742 spin_unlock_rd(&fdp->fd_spin);
2743 atomic_subtract_int(&fdp->fd_softrefs, 1);
2749 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
2750 0, 0, sysctl_kern_file, "S,file", "Entire file table");
2752 SYSCTL_INT(_kern, OID_AUTO, minfilesperproc, CTLFLAG_RW,
2753 &minfilesperproc, 0, "Minimum files allowed open per process");
2754 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
2755 &maxfilesperproc, 0, "Maximum files allowed open per process");
2756 SYSCTL_INT(_kern, OID_AUTO, maxfilesperuser, CTLFLAG_RW,
2757 &maxfilesperuser, 0, "Maximum files allowed open per user");
2759 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
2760 &maxfiles, 0, "Maximum number of files");
2762 SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW,
2763 &maxfilesrootres, 0, "Descriptors reserved for root use");
2765 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
2766 &nfiles, 0, "System-wide number of open files");
2769 fildesc_drvinit(void *unused)
2773 for (fd = 0; fd < NUMFDESC; fd++) {
2774 make_dev(&fildesc_ops, fd,
2775 UID_BIN, GID_BIN, 0666, "fd/%d", fd);
2778 make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin");
2779 make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout");
2780 make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr");
2786 struct fileops badfileops = {
2787 .fo_read = badfo_readwrite,
2788 .fo_write = badfo_readwrite,
2789 .fo_ioctl = badfo_ioctl,
2790 .fo_poll = badfo_poll,
2791 .fo_kqfilter = badfo_kqfilter,
2792 .fo_stat = badfo_stat,
2793 .fo_close = badfo_close,
2794 .fo_shutdown = badfo_shutdown
2808 badfo_ioctl(struct file *fp, u_long com, caddr_t data,
2809 struct ucred *cred, struct sysmsg *msgv)
2815 badfo_poll(struct file *fp, int events, struct ucred *cred)
2821 * Must return an error to prevent registration, typically
2822 * due to a revoked descriptor (file_filtops assigned).
2825 badfo_kqfilter(struct file *fp, struct knote *kn)
2827 return (EOPNOTSUPP);
2834 badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred)
2843 badfo_close(struct file *fp)
2852 badfo_shutdown(struct file *fp, int how)
2861 nofo_shutdown(struct file *fp, int how)
2863 return (EOPNOTSUPP);
2866 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,
2867 fildesc_drvinit,NULL)