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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>
83 #include <sys/filedesc.h>
84 #include <sys/kernel.h>
85 #include <sys/sysctl.h>
86 #include <sys/vnode.h>
88 #include <sys/nlookup.h>
91 #include <sys/filio.h>
92 #include <sys/fcntl.h>
93 #include <sys/unistd.h>
94 #include <sys/resourcevar.h>
95 #include <sys/event.h>
96 #include <sys/kern_syscall.h>
97 #include <sys/kcore.h>
98 #include <sys/kinfo.h>
102 #include <vm/vm_extern.h>
104 #include <sys/thread2.h>
105 #include <sys/file2.h>
106 #include <sys/spinlock2.h>
108 static void fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd);
109 static void fdreserve_locked (struct filedesc *fdp, int fd0, int incr);
110 static struct file *funsetfd_locked (struct filedesc *fdp, int fd);
111 static int checkfpclosed(struct filedesc *fdp, int fd, struct file *fp);
112 static void ffree(struct file *fp);
114 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table");
115 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader",
116 "file desc to leader structures");
117 MALLOC_DEFINE(M_FILE, "file", "Open file structure");
118 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");
120 static d_open_t fdopen;
123 #define CDEV_MAJOR 22
124 static struct dev_ops fildesc_ops = {
125 { "FD", CDEV_MAJOR, 0 },
129 static int badfo_readwrite (struct file *fp, struct uio *uio,
130 struct ucred *cred, int flags);
131 static int badfo_ioctl (struct file *fp, u_long com, caddr_t data,
133 static int badfo_poll (struct file *fp, int events, struct ucred *cred);
134 static int badfo_kqfilter (struct file *fp, struct knote *kn);
135 static int badfo_stat (struct file *fp, struct stat *sb, struct ucred *cred);
136 static int badfo_close (struct file *fp);
137 static int badfo_shutdown (struct file *fp, int how);
140 * Descriptor management.
142 static struct filelist filehead = LIST_HEAD_INITIALIZER(&filehead);
143 static struct spinlock filehead_spin = SPINLOCK_INITIALIZER(&filehead_spin);
144 static int nfiles; /* actual number of open files */
148 * Fixup fd_freefile and fd_lastfile after a descriptor has been cleared.
150 * MPSAFE - must be called with fdp->fd_spin exclusively held
154 fdfixup_locked(struct filedesc *fdp, int fd)
156 if (fd < fdp->fd_freefile) {
157 fdp->fd_freefile = fd;
159 while (fdp->fd_lastfile >= 0 &&
160 fdp->fd_files[fdp->fd_lastfile].fp == NULL &&
161 fdp->fd_files[fdp->fd_lastfile].reserved == 0
168 * System calls on descriptors.
173 sys_getdtablesize(struct getdtablesize_args *uap)
175 struct proc *p = curproc;
176 struct plimit *limit = p->p_limit;
178 spin_lock_rd(&limit->p_spin);
180 min((int)limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc);
181 spin_unlock_rd(&limit->p_spin);
186 * Duplicate a file descriptor to a particular value.
188 * note: keep in mind that a potential race condition exists when closing
189 * descriptors from a shared descriptor table (via rfork).
194 sys_dup2(struct dup2_args *uap)
199 error = kern_dup(DUP_FIXED, uap->from, uap->to, &fd);
200 uap->sysmsg_fds[0] = fd;
206 * Duplicate a file descriptor.
211 sys_dup(struct dup_args *uap)
216 error = kern_dup(DUP_VARIABLE, uap->fd, 0, &fd);
217 uap->sysmsg_fds[0] = fd;
223 * MPALMOSTSAFE - acquires mplock for fp operations
226 kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred)
228 struct thread *td = curthread;
229 struct proc *p = td->td_proc;
235 int tmp, error, flg = F_POSIX;
240 * Operations on file descriptors that do not require a file pointer.
244 error = fgetfdflags(p->p_fd, fd, &tmp);
246 dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0;
250 if (dat->fc_cloexec & FD_CLOEXEC)
251 error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE);
253 error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE);
257 error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd);
264 * Operations on file pointers
266 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
272 dat->fc_flags = OFLAGS(fp->f_flag);
278 nflags = FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS;
279 nflags |= oflags & ~FCNTLFLAGS;
282 if (((nflags ^ oflags) & O_APPEND) && (oflags & FAPPENDONLY))
284 if (error == 0 && ((nflags ^ oflags) & FASYNC)) {
285 tmp = nflags & FASYNC;
286 error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp, cred);
293 error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner, cred);
297 error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner, cred);
302 /* Fall into F_SETLK */
305 if (fp->f_type != DTYPE_VNODE) {
309 vp = (struct vnode *)fp->f_data;
312 * copyin/lockop may block
314 if (dat->fc_flock.l_whence == SEEK_CUR)
315 dat->fc_flock.l_start += fp->f_offset;
317 switch (dat->fc_flock.l_type) {
319 if ((fp->f_flag & FREAD) == 0) {
323 p->p_leader->p_flag |= P_ADVLOCK;
324 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
325 &dat->fc_flock, flg);
328 if ((fp->f_flag & FWRITE) == 0) {
332 p->p_leader->p_flag |= P_ADVLOCK;
333 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
334 &dat->fc_flock, flg);
337 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
338 &dat->fc_flock, F_POSIX);
346 * It is possible to race a close() on the descriptor while
347 * we were blocked getting the lock. If this occurs the
348 * close might not have caught the lock.
350 if (checkfpclosed(p->p_fd, fd, fp)) {
351 dat->fc_flock.l_whence = SEEK_SET;
352 dat->fc_flock.l_start = 0;
353 dat->fc_flock.l_len = 0;
354 dat->fc_flock.l_type = F_UNLCK;
355 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
356 F_UNLCK, &dat->fc_flock, F_POSIX);
361 if (fp->f_type != DTYPE_VNODE) {
365 vp = (struct vnode *)fp->f_data;
367 * copyin/lockop may block
369 if (dat->fc_flock.l_type != F_RDLCK &&
370 dat->fc_flock.l_type != F_WRLCK &&
371 dat->fc_flock.l_type != F_UNLCK) {
375 if (dat->fc_flock.l_whence == SEEK_CUR)
376 dat->fc_flock.l_start += fp->f_offset;
377 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK,
378 &dat->fc_flock, F_POSIX);
391 * The file control system call.
396 sys_fcntl(struct fcntl_args *uap)
403 dat.fc_fd = uap->arg;
406 dat.fc_cloexec = uap->arg;
409 dat.fc_flags = uap->arg;
412 dat.fc_owner = uap->arg;
417 error = copyin((caddr_t)uap->arg, &dat.fc_flock,
418 sizeof(struct flock));
424 error = kern_fcntl(uap->fd, uap->cmd, &dat, curproc->p_ucred);
429 uap->sysmsg_result = dat.fc_fd;
432 uap->sysmsg_result = dat.fc_cloexec;
435 uap->sysmsg_result = dat.fc_flags;
438 uap->sysmsg_result = dat.fc_owner;
440 error = copyout(&dat.fc_flock, (caddr_t)uap->arg,
441 sizeof(struct flock));
450 * Common code for dup, dup2, and fcntl(F_DUPFD).
452 * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells
453 * kern_dup() to destructively dup over an existing file descriptor if new
454 * is already open. DUP_VARIABLE tells kern_dup() to find the lowest
455 * unused file descriptor that is greater than or equal to new.
460 kern_dup(enum dup_type type, int old, int new, int *res)
462 struct thread *td = curthread;
463 struct proc *p = td->td_proc;
464 struct filedesc *fdp = p->p_fd;
472 * Verify that we have a valid descriptor to dup from and
473 * possibly to dup to.
476 spin_lock_wr(&fdp->fd_spin);
477 if (new < 0 || new > p->p_rlimit[RLIMIT_NOFILE].rlim_cur ||
478 new >= maxfilesperproc) {
479 spin_unlock_wr(&fdp->fd_spin);
482 if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) {
483 spin_unlock_wr(&fdp->fd_spin);
486 if (type == DUP_FIXED && old == new) {
488 spin_unlock_wr(&fdp->fd_spin);
491 fp = fdp->fd_files[old].fp;
492 oldflags = fdp->fd_files[old].fileflags;
493 fhold(fp); /* MPSAFE - can be called with a spinlock held */
496 * Allocate a new descriptor if DUP_VARIABLE, or expand the table
497 * if the requested descriptor is beyond the current table size.
499 * This can block. Retry if the source descriptor no longer matches
500 * or if our expectation in the expansion case races.
502 * If we are not expanding or allocating a new decriptor, then reset
503 * the target descriptor to a reserved state so we have a uniform
504 * setup for the next code block.
506 if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) {
507 spin_unlock_wr(&fdp->fd_spin);
508 error = fdalloc(p, new, &newfd);
509 spin_lock_wr(&fdp->fd_spin);
511 spin_unlock_wr(&fdp->fd_spin);
518 if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) {
519 fsetfd_locked(fdp, NULL, newfd);
520 spin_unlock_wr(&fdp->fd_spin);
525 * Check for expansion race
527 if (type != DUP_VARIABLE && new != newfd) {
528 fsetfd_locked(fdp, NULL, newfd);
529 spin_unlock_wr(&fdp->fd_spin);
534 * Check for ripout, newfd reused old (this case probably
538 fsetfd_locked(fdp, NULL, newfd);
539 spin_unlock_wr(&fdp->fd_spin);
546 if (fdp->fd_files[new].reserved) {
547 spin_unlock_wr(&fdp->fd_spin);
549 kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new);
550 tsleep(fdp, 0, "fdres", hz);
555 * If the target descriptor was never allocated we have
556 * to allocate it. If it was we have to clean out the
557 * old descriptor. delfp inherits the ref from the
560 delfp = fdp->fd_files[new].fp;
561 fdp->fd_files[new].fp = NULL;
562 fdp->fd_files[new].reserved = 1;
564 fdreserve_locked(fdp, new, 1);
565 if (new > fdp->fd_lastfile)
566 fdp->fd_lastfile = new;
572 * NOTE: still holding an exclusive spinlock
576 * If a descriptor is being overwritten we may hve to tell
577 * fdfree() to sleep to ensure that all relevant process
578 * leaders can be traversed in closef().
580 if (delfp != NULL && p->p_fdtol != NULL) {
581 fdp->fd_holdleaderscount++;
586 KASSERT(delfp == NULL || type == DUP_FIXED,
587 ("dup() picked an open file"));
590 * Duplicate the source descriptor, update lastfile. If the new
591 * descriptor was not allocated and we aren't replacing an existing
592 * descriptor we have to mark the descriptor as being in use.
594 * The fd_files[] array inherits fp's hold reference.
596 fsetfd_locked(fdp, fp, new);
597 fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE;
598 spin_unlock_wr(&fdp->fd_spin);
603 * If we dup'd over a valid file, we now own the reference to it
604 * and must dispose of it using closef() semantics (as if a
605 * close() were performed on it).
610 spin_lock_wr(&fdp->fd_spin);
611 fdp->fd_holdleaderscount--;
612 if (fdp->fd_holdleaderscount == 0 &&
613 fdp->fd_holdleaderswakeup != 0) {
614 fdp->fd_holdleaderswakeup = 0;
615 spin_unlock_wr(&fdp->fd_spin);
616 wakeup(&fdp->fd_holdleaderscount);
618 spin_unlock_wr(&fdp->fd_spin);
626 * If sigio is on the list associated with a process or process group,
627 * disable signalling from the device, remove sigio from the list and
631 funsetown(struct sigio *sigio)
636 *(sigio->sio_myref) = NULL;
638 if (sigio->sio_pgid < 0) {
639 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
641 } else /* if ((*sigiop)->sio_pgid > 0) */ {
642 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
645 crfree(sigio->sio_ucred);
646 kfree(sigio, M_SIGIO);
649 /* Free a list of sigio structures. */
651 funsetownlst(struct sigiolst *sigiolst)
655 while ((sigio = SLIST_FIRST(sigiolst)) != NULL)
660 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
662 * After permission checking, add a sigio structure to the sigio list for
663 * the process or process group.
666 fsetown(pid_t pgid, struct sigio **sigiop)
682 * Policy - Don't allow a process to FSETOWN a process
683 * in another session.
685 * Remove this test to allow maximum flexibility or
686 * restrict FSETOWN to the current process or process
687 * group for maximum safety.
689 if (proc->p_session != curproc->p_session)
693 } else /* if (pgid < 0) */ {
694 pgrp = pgfind(-pgid);
699 * Policy - Don't allow a process to FSETOWN a process
700 * in another session.
702 * Remove this test to allow maximum flexibility or
703 * restrict FSETOWN to the current process or process
704 * group for maximum safety.
706 if (pgrp->pg_session != curproc->p_session)
712 sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK);
714 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
715 sigio->sio_proc = proc;
717 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
718 sigio->sio_pgrp = pgrp;
720 sigio->sio_pgid = pgid;
721 sigio->sio_ucred = crhold(curproc->p_ucred);
722 /* It would be convenient if p_ruid was in ucred. */
723 sigio->sio_ruid = curproc->p_ucred->cr_ruid;
724 sigio->sio_myref = sigiop;
732 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
735 fgetown(struct sigio *sigio)
737 return (sigio != NULL ? sigio->sio_pgid : 0);
741 * Close many file descriptors.
746 sys_closefrom(struct closefrom_args *uap)
748 return(kern_closefrom(uap->fd));
752 * Close all file descriptors greater then or equal to fd
757 kern_closefrom(int fd)
759 struct thread *td = curthread;
760 struct proc *p = td->td_proc;
761 struct filedesc *fdp;
770 * NOTE: This function will skip unassociated descriptors and
771 * reserved descriptors that have not yet been assigned.
772 * fd_lastfile can change as a side effect of kern_close().
774 spin_lock_wr(&fdp->fd_spin);
775 while (fd <= fdp->fd_lastfile) {
776 if (fdp->fd_files[fd].fp != NULL) {
777 spin_unlock_wr(&fdp->fd_spin);
778 /* ok if this races another close */
779 if (kern_close(fd) == EINTR)
781 spin_lock_wr(&fdp->fd_spin);
785 spin_unlock_wr(&fdp->fd_spin);
790 * Close a file descriptor.
795 sys_close(struct close_args *uap)
797 return(kern_close(uap->fd));
801 * MPALMOSTSAFE - acquires mplock around knote_fdclose() calls
806 struct thread *td = curthread;
807 struct proc *p = td->td_proc;
808 struct filedesc *fdp;
816 spin_lock_wr(&fdp->fd_spin);
817 if ((fp = funsetfd_locked(fdp, fd)) == NULL) {
818 spin_unlock_wr(&fdp->fd_spin);
822 if (p->p_fdtol != NULL) {
824 * Ask fdfree() to sleep to ensure that all relevant
825 * process leaders can be traversed in closef().
827 fdp->fd_holdleaderscount++;
832 * we now hold the fp reference that used to be owned by the descriptor
835 spin_unlock_wr(&fdp->fd_spin);
836 if (fd < fdp->fd_knlistsize) {
838 if (fd < fdp->fd_knlistsize)
839 knote_fdclose(p, fd);
842 error = closef(fp, p);
844 spin_lock_wr(&fdp->fd_spin);
845 fdp->fd_holdleaderscount--;
846 if (fdp->fd_holdleaderscount == 0 &&
847 fdp->fd_holdleaderswakeup != 0) {
848 fdp->fd_holdleaderswakeup = 0;
849 spin_unlock_wr(&fdp->fd_spin);
850 wakeup(&fdp->fd_holdleaderscount);
852 spin_unlock_wr(&fdp->fd_spin);
859 * shutdown_args(int fd, int how)
862 kern_shutdown(int fd, int how)
864 struct thread *td = curthread;
865 struct proc *p = td->td_proc;
871 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
873 error = fo_shutdown(fp, how);
880 sys_shutdown(struct shutdown_args *uap)
884 error = kern_shutdown(uap->s, uap->how);
893 kern_fstat(int fd, struct stat *ub)
895 struct thread *td = curthread;
896 struct proc *p = td->td_proc;
902 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
904 error = fo_stat(fp, ub, p->p_ucred);
911 * Return status information about a file descriptor.
916 sys_fstat(struct fstat_args *uap)
921 error = kern_fstat(uap->fd, &st);
924 error = copyout(&st, uap->sb, sizeof(st));
929 * Return pathconf information about a file descriptor.
933 sys_fpathconf(struct fpathconf_args *uap)
935 struct thread *td = curthread;
936 struct proc *p = td->td_proc;
943 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
946 switch (fp->f_type) {
949 if (uap->name != _PC_PIPE_BUF) {
952 uap->sysmsg_result = PIPE_BUF;
958 vp = (struct vnode *)fp->f_data;
959 error = VOP_PATHCONF(vp, uap->name, uap->sysmsg_fds);
970 SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand, 0, "");
973 * Grow the file table so it can hold through descriptor (want).
975 * The fdp's spinlock must be held exclusively on entry and may be held
976 * exclusively on return. The spinlock may be cycled by the routine.
981 fdgrow_locked(struct filedesc *fdp, int want)
983 struct fdnode *newfiles;
984 struct fdnode *oldfiles;
989 /* nf has to be of the form 2^n - 1 */
991 } while (nf <= want);
993 spin_unlock_wr(&fdp->fd_spin);
994 newfiles = kmalloc(nf * sizeof(struct fdnode), M_FILEDESC, M_WAITOK);
995 spin_lock_wr(&fdp->fd_spin);
998 * We could have raced another extend while we were not holding
1001 if (fdp->fd_nfiles >= nf) {
1002 spin_unlock_wr(&fdp->fd_spin);
1003 kfree(newfiles, M_FILEDESC);
1004 spin_lock_wr(&fdp->fd_spin);
1008 * Copy the existing ofile and ofileflags arrays
1009 * and zero the new portion of each array.
1011 extra = nf - fdp->fd_nfiles;
1012 bcopy(fdp->fd_files, newfiles, fdp->fd_nfiles * sizeof(struct fdnode));
1013 bzero(&newfiles[fdp->fd_nfiles], extra * sizeof(struct fdnode));
1015 oldfiles = fdp->fd_files;
1016 fdp->fd_files = newfiles;
1017 fdp->fd_nfiles = nf;
1019 if (oldfiles != fdp->fd_builtin_files) {
1020 spin_unlock_wr(&fdp->fd_spin);
1021 kfree(oldfiles, M_FILEDESC);
1022 spin_lock_wr(&fdp->fd_spin);
1028 * Number of nodes in right subtree, including the root.
1031 right_subtree_size(int n)
1033 return (n ^ (n | (n + 1)));
1040 right_ancestor(int n)
1042 return (n | (n + 1));
1049 left_ancestor(int n)
1051 return ((n & (n + 1)) - 1);
1055 * Traverse the in-place binary tree buttom-up adjusting the allocation
1056 * count so scans can determine where free descriptors are located.
1058 * MPSAFE - caller must be holding an exclusive spinlock on fdp
1062 fdreserve_locked(struct filedesc *fdp, int fd, int incr)
1065 fdp->fd_files[fd].allocated += incr;
1066 KKASSERT(fdp->fd_files[fd].allocated >= 0);
1067 fd = left_ancestor(fd);
1072 * Reserve a file descriptor for the process. If no error occurs, the
1073 * caller MUST at some point call fsetfd() or assign a file pointer
1074 * or dispose of the reservation.
1079 fdalloc(struct proc *p, int want, int *result)
1081 struct filedesc *fdp = p->p_fd;
1082 int fd, rsize, rsum, node, lim;
1084 spin_lock_rd(&p->p_limit->p_spin);
1085 lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc);
1086 spin_unlock_rd(&p->p_limit->p_spin);
1089 spin_lock_wr(&fdp->fd_spin);
1090 if (want >= fdp->fd_nfiles)
1091 fdgrow_locked(fdp, want);
1094 * Search for a free descriptor starting at the higher
1095 * of want or fd_freefile. If that fails, consider
1096 * expanding the ofile array.
1098 * NOTE! the 'allocated' field is a cumulative recursive allocation
1099 * count. If we happen to see a value of 0 then we can shortcut
1100 * our search. Otherwise we run through through the tree going
1101 * down branches we know have free descriptor(s) until we hit a
1102 * leaf node. The leaf node will be free but will not necessarily
1103 * have an allocated field of 0.
1106 /* move up the tree looking for a subtree with a free node */
1107 for (fd = max(want, fdp->fd_freefile); fd < min(fdp->fd_nfiles, lim);
1108 fd = right_ancestor(fd)) {
1109 if (fdp->fd_files[fd].allocated == 0)
1112 rsize = right_subtree_size(fd);
1113 if (fdp->fd_files[fd].allocated == rsize)
1114 continue; /* right subtree full */
1117 * Free fd is in the right subtree of the tree rooted at fd.
1118 * Call that subtree R. Look for the smallest (leftmost)
1119 * subtree of R with an unallocated fd: continue moving
1120 * down the left branch until encountering a full left
1121 * subtree, then move to the right.
1123 for (rsum = 0, rsize /= 2; rsize > 0; rsize /= 2) {
1125 rsum += fdp->fd_files[node].allocated;
1126 if (fdp->fd_files[fd].allocated == rsum + rsize) {
1127 fd = node; /* move to the right */
1128 if (fdp->fd_files[node].allocated == 0)
1137 * No space in current array. Expand?
1139 if (fdp->fd_nfiles >= lim) {
1140 spin_unlock_wr(&fdp->fd_spin);
1143 fdgrow_locked(fdp, want);
1147 KKASSERT(fd < fdp->fd_nfiles);
1148 if (fd > fdp->fd_lastfile)
1149 fdp->fd_lastfile = fd;
1150 if (want <= fdp->fd_freefile)
1151 fdp->fd_freefile = fd;
1153 KKASSERT(fdp->fd_files[fd].fp == NULL);
1154 KKASSERT(fdp->fd_files[fd].reserved == 0);
1155 fdp->fd_files[fd].fileflags = 0;
1156 fdp->fd_files[fd].reserved = 1;
1157 fdreserve_locked(fdp, fd, 1);
1158 spin_unlock_wr(&fdp->fd_spin);
1163 * Check to see whether n user file descriptors
1164 * are available to the process p.
1169 fdavail(struct proc *p, int n)
1171 struct filedesc *fdp = p->p_fd;
1172 struct fdnode *fdnode;
1175 spin_lock_rd(&p->p_limit->p_spin);
1176 lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc);
1177 spin_unlock_rd(&p->p_limit->p_spin);
1179 spin_lock_rd(&fdp->fd_spin);
1180 if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) {
1181 spin_unlock_rd(&fdp->fd_spin);
1184 last = min(fdp->fd_nfiles, lim);
1185 fdnode = &fdp->fd_files[fdp->fd_freefile];
1186 for (i = last - fdp->fd_freefile; --i >= 0; ++fdnode) {
1187 if (fdnode->fp == NULL && --n <= 0) {
1188 spin_unlock_rd(&fdp->fd_spin);
1192 spin_unlock_rd(&fdp->fd_spin);
1197 * Revoke open descriptors referencing (f_data, f_type)
1199 * Any revoke executed within a prison is only able to
1200 * revoke descriptors for processes within that prison.
1202 * Returns 0 on success or an error code.
1204 struct fdrevoke_info {
1214 static int fdrevoke_check_callback(struct file *fp, void *vinfo);
1215 static int fdrevoke_proc_callback(struct proc *p, void *vinfo);
1218 fdrevoke(void *f_data, short f_type, struct ucred *cred)
1220 struct fdrevoke_info info;
1223 bzero(&info, sizeof(info));
1227 error = falloc(NULL, &info.nfp, NULL);
1232 * Scan the file pointer table once. dups do not dup file pointers,
1233 * only descriptors, so there is no leak. Set FREVOKED on the fps
1236 allfiles_scan_exclusive(fdrevoke_check_callback, &info);
1239 * If any fps were marked track down the related descriptors
1240 * and close them. Any dup()s at this point will notice
1241 * the FREVOKED already set in the fp and do the right thing.
1243 * Any fps with non-zero msgcounts (aka sent over a unix-domain
1244 * socket) bumped the intransit counter and will require a
1245 * scan. Races against fps leaving the socket are closed by
1246 * the socket code checking for FREVOKED.
1249 allproc_scan(fdrevoke_proc_callback, &info);
1251 unp_revoke_gc(info.nfp);
1257 * Locate matching file pointers directly.
1260 fdrevoke_check_callback(struct file *fp, void *vinfo)
1262 struct fdrevoke_info *info = vinfo;
1265 * File pointers already flagged for revokation are skipped.
1267 if (fp->f_flag & FREVOKED)
1271 * If revoking from a prison file pointers created outside of
1272 * that prison, or file pointers without creds, cannot be revoked.
1274 if (info->cred->cr_prison &&
1275 (fp->f_cred == NULL ||
1276 info->cred->cr_prison != fp->f_cred->cr_prison)) {
1281 * If the file pointer matches then mark it for revocation. The
1282 * flag is currently only used by unp_revoke_gc().
1284 * info->count is a heuristic and can race in a SMP environment.
1286 if (info->data == fp->f_data && info->type == fp->f_type) {
1287 atomic_set_int(&fp->f_flag, FREVOKED);
1288 info->count += fp->f_count;
1296 * Locate matching file pointers via process descriptor tables.
1299 fdrevoke_proc_callback(struct proc *p, void *vinfo)
1301 struct fdrevoke_info *info = vinfo;
1302 struct filedesc *fdp;
1306 if (p->p_stat == SIDL || p->p_stat == SZOMB)
1308 if (info->cred->cr_prison &&
1309 info->cred->cr_prison != p->p_ucred->cr_prison) {
1314 * If the controlling terminal of the process matches the
1315 * vnode being revoked we clear the controlling terminal.
1317 * The normal spec_close() may not catch this because it
1318 * uses curproc instead of p.
1320 if (p->p_session && info->type == DTYPE_VNODE &&
1321 info->data == p->p_session->s_ttyvp) {
1322 p->p_session->s_ttyvp = NULL;
1327 * Softref the fdp to prevent it from being destroyed
1329 spin_lock_wr(&p->p_spin);
1330 if ((fdp = p->p_fd) == NULL) {
1331 spin_unlock_wr(&p->p_spin);
1334 atomic_add_int(&fdp->fd_softrefs, 1);
1335 spin_unlock_wr(&p->p_spin);
1338 * Locate and close any matching file descriptors.
1340 spin_lock_wr(&fdp->fd_spin);
1341 for (n = 0; n < fdp->fd_nfiles; ++n) {
1342 if ((fp = fdp->fd_files[n].fp) == NULL)
1344 if (fp->f_flag & FREVOKED) {
1346 fdp->fd_files[n].fp = info->nfp;
1347 spin_unlock_wr(&fdp->fd_spin);
1349 spin_lock_wr(&fdp->fd_spin);
1353 spin_unlock_wr(&fdp->fd_spin);
1354 atomic_subtract_int(&fdp->fd_softrefs, 1);
1360 * Create a new open file structure and reserve a file decriptor
1361 * for the process that refers to it.
1363 * Root creds are checked using p, or assumed if p is NULL. If
1364 * resultfd is non-NULL then p must also be non-NULL. No file
1365 * descriptor is reserved if resultfd is NULL.
1367 * A file pointer with a refcount of 1 is returned. Note that the
1368 * file pointer is NOT associated with the descriptor. If falloc
1369 * returns success, fsetfd() MUST be called to either associate the
1370 * file pointer or clear the reservation.
1375 falloc(struct proc *p, struct file **resultfp, int *resultfd)
1377 static struct timeval lastfail;
1385 * Handle filetable full issues and root overfill.
1387 if (nfiles >= maxfiles - maxfilesrootres &&
1388 ((p && p->p_ucred->cr_ruid != 0) || nfiles >= maxfiles)) {
1389 if (ppsratecheck(&lastfail, &curfail, 1)) {
1390 kprintf("kern.maxfiles limit exceeded by uid %d, please see tuning(7).\n",
1391 (p ? p->p_ucred->cr_ruid : -1));
1398 * Allocate a new file descriptor.
1400 fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO);
1401 spin_init(&fp->f_spin);
1403 fp->f_ops = &badfileops;
1406 fp->f_cred = crhold(p->p_ucred);
1408 fp->f_cred = crhold(proc0.p_ucred);
1409 spin_lock_wr(&filehead_spin);
1411 LIST_INSERT_HEAD(&filehead, fp, f_list);
1412 spin_unlock_wr(&filehead_spin);
1414 if ((error = fdalloc(p, 0, resultfd)) != 0) {
1431 checkfpclosed(struct filedesc *fdp, int fd, struct file *fp)
1435 spin_lock_rd(&fdp->fd_spin);
1436 if ((unsigned) fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp)
1440 spin_unlock_rd(&fdp->fd_spin);
1445 * Associate a file pointer with a previously reserved file descriptor.
1446 * This function always succeeds.
1448 * If fp is NULL, the file descriptor is returned to the pool.
1452 * MPSAFE (exclusive spinlock must be held on call)
1455 fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd)
1457 KKASSERT((unsigned)fd < fdp->fd_nfiles);
1458 KKASSERT(fdp->fd_files[fd].reserved != 0);
1461 fdp->fd_files[fd].fp = fp;
1462 fdp->fd_files[fd].reserved = 0;
1463 if (fp->f_type == DTYPE_KQUEUE) {
1464 if (fdp->fd_knlistsize < 0)
1465 fdp->fd_knlistsize = 0;
1468 fdp->fd_files[fd].reserved = 0;
1469 fdreserve_locked(fdp, fd, -1);
1470 fdfixup_locked(fdp, fd);
1478 fsetfd(struct proc *p, struct file *fp, int fd)
1480 struct filedesc *fdp = p->p_fd;
1482 spin_lock_wr(&fdp->fd_spin);
1483 fsetfd_locked(fdp, fp, fd);
1484 spin_unlock_wr(&fdp->fd_spin);
1488 * MPSAFE (exclusive spinlock must be held on call)
1492 funsetfd_locked(struct filedesc *fdp, int fd)
1496 if ((unsigned)fd >= fdp->fd_nfiles)
1498 if ((fp = fdp->fd_files[fd].fp) == NULL)
1500 fdp->fd_files[fd].fp = NULL;
1501 fdp->fd_files[fd].fileflags = 0;
1503 fdreserve_locked(fdp, fd, -1);
1504 fdfixup_locked(fdp, fd);
1512 fgetfdflags(struct filedesc *fdp, int fd, int *flagsp)
1516 spin_lock_rd(&fdp->fd_spin);
1517 if (((u_int)fd) >= fdp->fd_nfiles) {
1519 } else if (fdp->fd_files[fd].fp == NULL) {
1522 *flagsp = fdp->fd_files[fd].fileflags;
1525 spin_unlock_rd(&fdp->fd_spin);
1533 fsetfdflags(struct filedesc *fdp, int fd, int add_flags)
1537 spin_lock_wr(&fdp->fd_spin);
1538 if (((u_int)fd) >= fdp->fd_nfiles) {
1540 } else if (fdp->fd_files[fd].fp == NULL) {
1543 fdp->fd_files[fd].fileflags |= add_flags;
1546 spin_unlock_wr(&fdp->fd_spin);
1554 fclrfdflags(struct filedesc *fdp, int fd, int rem_flags)
1558 spin_lock_wr(&fdp->fd_spin);
1559 if (((u_int)fd) >= fdp->fd_nfiles) {
1561 } else if (fdp->fd_files[fd].fp == NULL) {
1564 fdp->fd_files[fd].fileflags &= ~rem_flags;
1567 spin_unlock_wr(&fdp->fd_spin);
1572 fsetcred(struct file *fp, struct ucred *cr)
1580 * Free a file descriptor.
1584 ffree(struct file *fp)
1586 KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!"));
1587 spin_lock_wr(&filehead_spin);
1588 LIST_REMOVE(fp, f_list);
1590 spin_unlock_wr(&filehead_spin);
1592 if (fp->f_nchandle.ncp)
1593 cache_drop(&fp->f_nchandle);
1598 * called from init_main, initialize filedesc0 for proc0.
1601 fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask)
1605 fdp0->fd_refcnt = 1;
1606 fdp0->fd_cmask = cmask;
1607 fdp0->fd_files = fdp0->fd_builtin_files;
1608 fdp0->fd_nfiles = NDFILE;
1609 fdp0->fd_lastfile = -1;
1610 spin_init(&fdp0->fd_spin);
1614 * Build a new filedesc structure.
1619 fdinit(struct proc *p)
1621 struct filedesc *newfdp;
1622 struct filedesc *fdp = p->p_fd;
1624 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO);
1625 spin_lock_rd(&fdp->fd_spin);
1627 newfdp->fd_cdir = fdp->fd_cdir;
1628 vref(newfdp->fd_cdir);
1629 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1633 * rdir may not be set in e.g. proc0 or anything vm_fork'd off of
1634 * proc0, but should unconditionally exist in other processes.
1637 newfdp->fd_rdir = fdp->fd_rdir;
1638 vref(newfdp->fd_rdir);
1639 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1642 newfdp->fd_jdir = fdp->fd_jdir;
1643 vref(newfdp->fd_jdir);
1644 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1646 spin_unlock_rd(&fdp->fd_spin);
1648 /* Create the file descriptor table. */
1649 newfdp->fd_refcnt = 1;
1650 newfdp->fd_cmask = cmask;
1651 newfdp->fd_files = newfdp->fd_builtin_files;
1652 newfdp->fd_nfiles = NDFILE;
1653 newfdp->fd_knlistsize = -1;
1654 newfdp->fd_lastfile = -1;
1655 spin_init(&newfdp->fd_spin);
1661 * Share a filedesc structure.
1666 fdshare(struct proc *p)
1668 struct filedesc *fdp;
1671 spin_lock_wr(&fdp->fd_spin);
1673 spin_unlock_wr(&fdp->fd_spin);
1678 * Copy a filedesc structure.
1683 fdcopy(struct proc *p)
1685 struct filedesc *fdp = p->p_fd;
1686 struct filedesc *newfdp;
1687 struct fdnode *fdnode;
1692 * Certain daemons might not have file descriptors.
1698 * Allocate the new filedesc and fd_files[] array. This can race
1699 * with operations by other threads on the fdp so we have to be
1702 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO);
1704 spin_lock_rd(&fdp->fd_spin);
1705 if (fdp->fd_lastfile < NDFILE) {
1706 newfdp->fd_files = newfdp->fd_builtin_files;
1710 * We have to allocate (N^2-1) entries for our in-place
1711 * binary tree. Allow the table to shrink.
1715 while (ni > fdp->fd_lastfile && ni > NDFILE) {
1719 spin_unlock_rd(&fdp->fd_spin);
1720 newfdp->fd_files = kmalloc(i * sizeof(struct fdnode),
1721 M_FILEDESC, M_WAITOK | M_ZERO);
1724 * Check for race, retry
1726 spin_lock_rd(&fdp->fd_spin);
1727 if (i <= fdp->fd_lastfile) {
1728 spin_unlock_rd(&fdp->fd_spin);
1729 kfree(newfdp->fd_files, M_FILEDESC);
1735 * Dup the remaining fields. vref() and cache_hold() can be
1736 * safely called while holding the read spinlock on fdp.
1738 * The read spinlock on fdp is still being held.
1740 * NOTE: vref and cache_hold calls for the case where the vnode
1741 * or cache entry already has at least one ref may be called
1742 * while holding spin locks.
1744 if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) {
1745 vref(newfdp->fd_cdir);
1746 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1749 * We must check for fd_rdir here, at least for now because
1750 * the init process is created before we have access to the
1751 * rootvode to take a reference to it.
1753 if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) {
1754 vref(newfdp->fd_rdir);
1755 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1757 if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) {
1758 vref(newfdp->fd_jdir);
1759 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1761 newfdp->fd_refcnt = 1;
1762 newfdp->fd_nfiles = i;
1763 newfdp->fd_lastfile = fdp->fd_lastfile;
1764 newfdp->fd_freefile = fdp->fd_freefile;
1765 newfdp->fd_cmask = fdp->fd_cmask;
1766 newfdp->fd_knlist = NULL;
1767 newfdp->fd_knlistsize = -1;
1768 newfdp->fd_knhash = NULL;
1769 newfdp->fd_knhashmask = 0;
1770 spin_init(&newfdp->fd_spin);
1773 * Copy the descriptor table through (i). This also copies the
1774 * allocation state. Then go through and ref the file pointers
1775 * and clean up any KQ descriptors.
1777 * kq descriptors cannot be copied. Since we haven't ref'd the
1778 * copied files yet we can ignore the return value from funsetfd().
1780 * The read spinlock on fdp is still being held.
1782 bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode));
1783 for (i = 0 ; i < newfdp->fd_nfiles; ++i) {
1784 fdnode = &newfdp->fd_files[i];
1785 if (fdnode->reserved) {
1786 fdreserve_locked(newfdp, i, -1);
1787 fdnode->reserved = 0;
1788 fdfixup_locked(newfdp, i);
1789 } else if (fdnode->fp) {
1790 if (fdnode->fp->f_type == DTYPE_KQUEUE) {
1791 (void)funsetfd_locked(newfdp, i);
1797 spin_unlock_rd(&fdp->fd_spin);
1802 * Release a filedesc structure.
1804 * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE)
1807 fdfree(struct proc *p, struct filedesc *repl)
1809 struct filedesc *fdp;
1810 struct fdnode *fdnode;
1812 struct filedesc_to_leader *fdtol;
1818 * Certain daemons might not have file descriptors.
1827 * Severe messing around to follow.
1829 spin_lock_wr(&fdp->fd_spin);
1831 /* Check for special need to clear POSIX style locks */
1833 if (fdtol != NULL) {
1834 KASSERT(fdtol->fdl_refcount > 0,
1835 ("filedesc_to_refcount botch: fdl_refcount=%d",
1836 fdtol->fdl_refcount));
1837 if (fdtol->fdl_refcount == 1 &&
1838 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1839 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1840 fdnode = &fdp->fd_files[i];
1841 if (fdnode->fp == NULL ||
1842 fdnode->fp->f_type != DTYPE_VNODE) {
1847 spin_unlock_wr(&fdp->fd_spin);
1849 lf.l_whence = SEEK_SET;
1852 lf.l_type = F_UNLCK;
1853 vp = (struct vnode *)fp->f_data;
1854 (void) VOP_ADVLOCK(vp,
1855 (caddr_t)p->p_leader,
1860 spin_lock_wr(&fdp->fd_spin);
1864 if (fdtol->fdl_refcount == 1) {
1865 if (fdp->fd_holdleaderscount > 0 &&
1866 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1868 * close() or do_dup() has cleared a reference
1869 * in a shared file descriptor table.
1871 fdp->fd_holdleaderswakeup = 1;
1872 msleep(&fdp->fd_holdleaderscount,
1873 &fdp->fd_spin, 0, "fdlhold", 0);
1876 if (fdtol->fdl_holdcount > 0) {
1878 * Ensure that fdtol->fdl_leader
1879 * remains valid in closef().
1881 fdtol->fdl_wakeup = 1;
1882 msleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0);
1886 fdtol->fdl_refcount--;
1887 if (fdtol->fdl_refcount == 0 &&
1888 fdtol->fdl_holdcount == 0) {
1889 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev;
1890 fdtol->fdl_prev->fdl_next = fdtol->fdl_next;
1895 if (fdtol != NULL) {
1896 spin_unlock_wr(&fdp->fd_spin);
1897 kfree(fdtol, M_FILEDESC_TO_LEADER);
1898 spin_lock_wr(&fdp->fd_spin);
1901 if (--fdp->fd_refcnt > 0) {
1902 spin_unlock_wr(&fdp->fd_spin);
1903 spin_lock_wr(&p->p_spin);
1905 spin_unlock_wr(&p->p_spin);
1910 * Even though we are the last reference to the structure allproc
1911 * scans may still reference the structure. Maintain proper
1912 * locks until we can replace p->p_fd.
1914 * Also note that kqueue's closef still needs to reference the
1915 * fdp via p->p_fd, so we have to close the descriptors before
1916 * we replace p->p_fd.
1918 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1919 if (fdp->fd_files[i].fp) {
1920 fp = funsetfd_locked(fdp, i);
1922 spin_unlock_wr(&fdp->fd_spin);
1924 spin_lock_wr(&fdp->fd_spin);
1928 spin_unlock_wr(&fdp->fd_spin);
1931 * Interlock against an allproc scan operations (typically frevoke).
1933 spin_lock_wr(&p->p_spin);
1935 spin_unlock_wr(&p->p_spin);
1938 * Wait for any softrefs to go away. This race rarely occurs so
1939 * we can use a non-critical-path style poll/sleep loop. The
1940 * race only occurs against allproc scans.
1942 * No new softrefs can occur with the fdp disconnected from the
1945 if (fdp->fd_softrefs) {
1946 kprintf("pid %d: Warning, fdp race avoided\n", p->p_pid);
1947 while (fdp->fd_softrefs)
1948 tsleep(&fdp->fd_softrefs, 0, "fdsoft", 1);
1951 if (fdp->fd_files != fdp->fd_builtin_files)
1952 kfree(fdp->fd_files, M_FILEDESC);
1954 cache_drop(&fdp->fd_ncdir);
1955 vrele(fdp->fd_cdir);
1958 cache_drop(&fdp->fd_nrdir);
1959 vrele(fdp->fd_rdir);
1962 cache_drop(&fdp->fd_njdir);
1963 vrele(fdp->fd_jdir);
1966 kfree(fdp->fd_knlist, M_KQUEUE);
1968 kfree(fdp->fd_knhash, M_KQUEUE);
1969 kfree(fdp, M_FILEDESC);
1973 * Retrieve and reference the file pointer associated with a descriptor.
1978 holdfp(struct filedesc *fdp, int fd, int flag)
1982 spin_lock_rd(&fdp->fd_spin);
1983 if (((u_int)fd) >= fdp->fd_nfiles) {
1987 if ((fp = fdp->fd_files[fd].fp) == NULL)
1989 if ((fp->f_flag & flag) == 0 && flag != -1) {
1995 spin_unlock_rd(&fdp->fd_spin);
2000 * holdsock() - load the struct file pointer associated
2001 * with a socket into *fpp. If an error occurs, non-zero
2002 * will be returned and *fpp will be set to NULL.
2007 holdsock(struct filedesc *fdp, int fd, struct file **fpp)
2012 spin_lock_rd(&fdp->fd_spin);
2013 if ((unsigned)fd >= fdp->fd_nfiles) {
2018 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2022 if (fp->f_type != DTYPE_SOCKET) {
2029 spin_unlock_rd(&fdp->fd_spin);
2035 * Convert a user file descriptor to a held file pointer.
2040 holdvnode(struct filedesc *fdp, int fd, struct file **fpp)
2045 spin_lock_rd(&fdp->fd_spin);
2046 if ((unsigned)fd >= fdp->fd_nfiles) {
2051 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2055 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) {
2063 spin_unlock_rd(&fdp->fd_spin);
2069 * For setugid programs, we don't want to people to use that setugidness
2070 * to generate error messages which write to a file which otherwise would
2071 * otherwise be off-limits to the process.
2073 * This is a gross hack to plug the hole. A better solution would involve
2074 * a special vop or other form of generalized access control mechanism. We
2075 * go ahead and just reject all procfs file systems accesses as dangerous.
2077 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is
2078 * sufficient. We also don't for check setugidness since we know we are.
2081 is_unsafe(struct file *fp)
2083 if (fp->f_type == DTYPE_VNODE &&
2084 ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS)
2090 * Make this setguid thing safe, if at all possible.
2092 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2095 setugidsafety(struct proc *p)
2097 struct filedesc *fdp = p->p_fd;
2100 /* Certain daemons might not have file descriptors. */
2105 * note: fdp->fd_files may be reallocated out from under us while
2106 * we are blocked in a close. Be careful!
2108 for (i = 0; i <= fdp->fd_lastfile; i++) {
2111 if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) {
2114 if (i < fdp->fd_knlistsize)
2115 knote_fdclose(p, i);
2117 * NULL-out descriptor prior to close to avoid
2118 * a race while close blocks.
2120 if ((fp = funsetfd_locked(fdp, i)) != NULL)
2127 * Close any files on exec?
2129 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2132 fdcloseexec(struct proc *p)
2134 struct filedesc *fdp = p->p_fd;
2137 /* Certain daemons might not have file descriptors. */
2142 * We cannot cache fd_files since operations may block and rip
2143 * them out from under us.
2145 for (i = 0; i <= fdp->fd_lastfile; i++) {
2146 if (fdp->fd_files[i].fp != NULL &&
2147 (fdp->fd_files[i].fileflags & UF_EXCLOSE)) {
2150 if (i < fdp->fd_knlistsize)
2151 knote_fdclose(p, i);
2153 * NULL-out descriptor prior to close to avoid
2154 * a race while close blocks.
2156 if ((fp = funsetfd_locked(fdp, i)) != NULL)
2163 * It is unsafe for set[ug]id processes to be started with file
2164 * descriptors 0..2 closed, as these descriptors are given implicit
2165 * significance in the Standard C library. fdcheckstd() will create a
2166 * descriptor referencing /dev/null for each of stdin, stdout, and
2167 * stderr that is not already open.
2169 * NOT MPSAFE - calls falloc, vn_open, etc
2172 fdcheckstd(struct proc *p)
2174 struct nlookupdata nd;
2175 struct filedesc *fdp;
2178 int i, error, flags, devnull;
2185 for (i = 0; i < 3; i++) {
2186 if (fdp->fd_files[i].fp != NULL)
2189 if ((error = falloc(p, &fp, &devnull)) != 0)
2192 error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE,
2193 NLC_FOLLOW|NLC_LOCKVP);
2194 flags = FREAD | FWRITE;
2196 error = vn_open(&nd, fp, flags, 0);
2198 fsetfd(p, fp, devnull);
2200 fsetfd(p, NULL, devnull);
2205 KKASSERT(i == devnull);
2207 error = kern_dup(DUP_FIXED, devnull, i, &retval);
2216 * Internal form of close.
2217 * Decrement reference count on file structure.
2218 * Note: td and/or p may be NULL when closing a file
2219 * that was being passed in a message.
2221 * MPALMOSTSAFE - acquires mplock for VOP operations
2224 closef(struct file *fp, struct proc *p)
2228 struct filedesc_to_leader *fdtol;
2234 * POSIX record locking dictates that any close releases ALL
2235 * locks owned by this process. This is handled by setting
2236 * a flag in the unlock to free ONLY locks obeying POSIX
2237 * semantics, and not to free BSD-style file locks.
2238 * If the descriptor was in a message, POSIX-style locks
2239 * aren't passed with the descriptor.
2241 if (p != NULL && fp->f_type == DTYPE_VNODE &&
2242 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2245 if ((p->p_leader->p_flag & P_ADVLOCK) != 0) {
2246 lf.l_whence = SEEK_SET;
2249 lf.l_type = F_UNLCK;
2250 vp = (struct vnode *)fp->f_data;
2251 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
2255 if (fdtol != NULL) {
2257 * Handle special case where file descriptor table
2258 * is shared between multiple process leaders.
2260 for (fdtol = fdtol->fdl_next;
2261 fdtol != p->p_fdtol;
2262 fdtol = fdtol->fdl_next) {
2263 if ((fdtol->fdl_leader->p_flag &
2266 fdtol->fdl_holdcount++;
2267 lf.l_whence = SEEK_SET;
2270 lf.l_type = F_UNLCK;
2271 vp = (struct vnode *)fp->f_data;
2272 (void) VOP_ADVLOCK(vp,
2273 (caddr_t)fdtol->fdl_leader,
2274 F_UNLCK, &lf, F_POSIX);
2275 fdtol->fdl_holdcount--;
2276 if (fdtol->fdl_holdcount == 0 &&
2277 fdtol->fdl_wakeup != 0) {
2278 fdtol->fdl_wakeup = 0;
2291 * fhold() can only be called if f_count is already at least 1 (i.e. the
2292 * caller of fhold() already has a reference to the file pointer in some
2295 * f_count is not spin-locked. Instead, atomic ops are used for
2296 * incrementing, decrementing, and handling the 1->0 transition.
2299 fhold(struct file *fp)
2301 atomic_add_int(&fp->f_count, 1);
2305 * fdrop() - drop a reference to a descriptor
2307 * MPALMOSTSAFE - acquires mplock for final close sequence
2310 fdrop(struct file *fp)
2317 * A combined fetch and subtract is needed to properly detect
2318 * 1->0 transitions, otherwise two cpus dropping from a ref
2319 * count of 2 might both try to run the 1->0 code.
2321 if (atomic_fetchadd_int(&fp->f_count, -1) > 1)
2327 * The last reference has gone away, we own the fp structure free
2330 if (fp->f_count < 0)
2331 panic("fdrop: count < 0");
2332 if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE &&
2333 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2335 lf.l_whence = SEEK_SET;
2338 lf.l_type = F_UNLCK;
2339 vp = (struct vnode *)fp->f_data;
2340 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2342 if (fp->f_ops != &badfileops)
2343 error = fo_close(fp);
2352 * Apply an advisory lock on a file descriptor.
2354 * Just attempt to get a record lock of the requested type on
2355 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
2358 sys_flock(struct flock_args *uap)
2360 struct proc *p = curproc;
2366 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
2368 if (fp->f_type != DTYPE_VNODE) {
2372 vp = (struct vnode *)fp->f_data;
2373 lf.l_whence = SEEK_SET;
2376 if (uap->how & LOCK_UN) {
2377 lf.l_type = F_UNLCK;
2378 fp->f_flag &= ~FHASLOCK;
2379 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2382 if (uap->how & LOCK_EX)
2383 lf.l_type = F_WRLCK;
2384 else if (uap->how & LOCK_SH)
2385 lf.l_type = F_RDLCK;
2390 fp->f_flag |= FHASLOCK;
2391 if (uap->how & LOCK_NB)
2392 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0);
2394 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT);
2401 * File Descriptor pseudo-device driver (/dev/fd/).
2403 * Opening minor device N dup()s the file (if any) connected to file
2404 * descriptor N belonging to the calling process. Note that this driver
2405 * consists of only the ``open()'' routine, because all subsequent
2406 * references to this file will be direct to the other driver.
2410 fdopen(struct dev_open_args *ap)
2412 thread_t td = curthread;
2414 KKASSERT(td->td_lwp != NULL);
2417 * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the
2418 * the file descriptor being sought for duplication. The error
2419 * return ensures that the vnode for this device will be released
2420 * by vn_open. Open will detect this special error and take the
2421 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
2422 * will simply report the error.
2424 td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev);
2429 * The caller has reserved the file descriptor dfd for us. On success we
2430 * must fsetfd() it. On failure the caller will clean it up.
2432 * NOT MPSAFE - isn't getting spinlocks, possibly other things
2435 dupfdopen(struct proc *p, int dfd, int sfd, int mode, int error)
2437 struct filedesc *fdp = p->p_fd;
2442 if ((wfp = holdfp(fdp, sfd, -1)) == NULL)
2446 * Close a revoke/dup race. Duping a descriptor marked as revoked
2447 * will dup a dummy descriptor instead of the real one.
2449 if (wfp->f_flag & FREVOKED) {
2450 kprintf("Warning: attempt to dup() a revoked descriptor\n");
2453 werror = falloc(NULL, &wfp, NULL);
2459 * There are two cases of interest here.
2461 * For ENODEV simply dup sfd to file descriptor dfd and return.
2463 * For ENXIO steal away the file structure from sfd and store it
2464 * dfd. sfd is effectively closed by this operation.
2466 * Any other error code is just returned.
2471 * Check that the mode the file is being opened for is a
2472 * subset of the mode of the existing descriptor.
2474 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
2478 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2479 fsetfd(p, wfp, dfd);
2484 * Steal away the file pointer from dfd, and stuff it into indx.
2486 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2487 fsetfd(p, wfp, dfd);
2488 if ((xfp = funsetfd_locked(fdp, sfd)) != NULL)
2500 * NOT MPSAFE - I think these refer to a common file descriptor table
2501 * and we need to spinlock that to link fdtol in.
2503 struct filedesc_to_leader *
2504 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
2505 struct proc *leader)
2507 struct filedesc_to_leader *fdtol;
2509 fdtol = kmalloc(sizeof(struct filedesc_to_leader),
2510 M_FILEDESC_TO_LEADER, M_WAITOK);
2511 fdtol->fdl_refcount = 1;
2512 fdtol->fdl_holdcount = 0;
2513 fdtol->fdl_wakeup = 0;
2514 fdtol->fdl_leader = leader;
2516 fdtol->fdl_next = old->fdl_next;
2517 fdtol->fdl_prev = old;
2518 old->fdl_next = fdtol;
2519 fdtol->fdl_next->fdl_prev = fdtol;
2521 fdtol->fdl_next = fdtol;
2522 fdtol->fdl_prev = fdtol;
2528 * Scan all file pointers in the system. The callback is made with
2529 * the master list spinlock held exclusively.
2534 allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data)
2539 spin_lock_wr(&filehead_spin);
2540 LIST_FOREACH(fp, &filehead, f_list) {
2541 res = callback(fp, data);
2545 spin_unlock_wr(&filehead_spin);
2549 * Get file structures.
2551 * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe)
2554 struct sysctl_kern_file_info {
2557 struct sysctl_req *req;
2560 static int sysctl_kern_file_callback(struct proc *p, void *data);
2563 sysctl_kern_file(SYSCTL_HANDLER_ARGS)
2565 struct sysctl_kern_file_info info;
2568 * Note: because the number of file descriptors is calculated
2569 * in different ways for sizing vs returning the data,
2570 * there is information leakage from the first loop. However,
2571 * it is of a similar order of magnitude to the leakage from
2572 * global system statistics such as kern.openfiles.
2574 * When just doing a count, note that we cannot just count
2575 * the elements and add f_count via the filehead list because
2576 * threaded processes share their descriptor table and f_count might
2577 * still be '1' in that case.
2579 * Since the SYSCTL op can block, we must hold the process to
2580 * prevent it being ripped out from under us either in the
2581 * file descriptor loop or in the greater LIST_FOREACH. The
2582 * process may be in varying states of disrepair. If the process
2583 * is in SZOMB we may have caught it just as it is being removed
2584 * from the allproc list, we must skip it in that case to maintain
2585 * an unbroken chain through the allproc list.
2590 allproc_scan(sysctl_kern_file_callback, &info);
2593 * When just calculating the size, overestimate a bit to try to
2594 * prevent system activity from causing the buffer-fill call
2597 if (req->oldptr == NULL) {
2598 info.count = (info.count + 16) + (info.count / 10);
2599 info.error = SYSCTL_OUT(req, NULL,
2600 info.count * sizeof(struct kinfo_file));
2602 return (info.error);
2606 sysctl_kern_file_callback(struct proc *p, void *data)
2608 struct sysctl_kern_file_info *info = data;
2609 struct kinfo_file kf;
2610 struct filedesc *fdp;
2615 if (p->p_stat == SIDL || p->p_stat == SZOMB)
2617 if (!PRISON_CHECK(info->req->td->td_proc->p_ucred, p->p_ucred) != 0)
2621 * Softref the fdp to prevent it from being destroyed
2623 spin_lock_wr(&p->p_spin);
2624 if ((fdp = p->p_fd) == NULL) {
2625 spin_unlock_wr(&p->p_spin);
2628 atomic_add_int(&fdp->fd_softrefs, 1);
2629 spin_unlock_wr(&p->p_spin);
2632 * The fdp's own spinlock prevents the contents from being
2635 spin_lock_rd(&fdp->fd_spin);
2636 for (n = 0; n < fdp->fd_nfiles; ++n) {
2637 if ((fp = fdp->fd_files[n].fp) == NULL)
2639 if (info->req->oldptr == NULL) {
2642 uid = p->p_ucred ? p->p_ucred->cr_uid : -1;
2643 kcore_make_file(&kf, fp, p->p_pid, uid, n);
2644 spin_unlock_rd(&fdp->fd_spin);
2645 info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf));
2646 spin_lock_rd(&fdp->fd_spin);
2651 spin_unlock_rd(&fdp->fd_spin);
2652 atomic_subtract_int(&fdp->fd_softrefs, 1);
2658 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
2659 0, 0, sysctl_kern_file, "S,file", "Entire file table");
2661 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
2662 &maxfilesperproc, 0, "Maximum files allowed open per process");
2664 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
2665 &maxfiles, 0, "Maximum number of files");
2667 SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW,
2668 &maxfilesrootres, 0, "Descriptors reserved for root use");
2670 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
2671 &nfiles, 0, "System-wide number of open files");
2674 fildesc_drvinit(void *unused)
2678 for (fd = 0; fd < NUMFDESC; fd++) {
2679 make_dev(&fildesc_ops, fd,
2680 UID_BIN, GID_BIN, 0666, "fd/%d", fd);
2683 kprintf("fildesc_drvinit() building stdin, stdout, stderr: \n");
2685 make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin");
2686 make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout");
2687 make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr");
2693 struct fileops badfileops = {
2694 .fo_read = badfo_readwrite,
2695 .fo_write = badfo_readwrite,
2696 .fo_ioctl = badfo_ioctl,
2697 .fo_poll = badfo_poll,
2698 .fo_kqfilter = badfo_kqfilter,
2699 .fo_stat = badfo_stat,
2700 .fo_close = badfo_close,
2701 .fo_shutdown = badfo_shutdown
2721 badfo_ioctl(struct file *fp, u_long com, caddr_t data, struct ucred *cred)
2730 badfo_poll(struct file *fp, int events, struct ucred *cred)
2739 badfo_kqfilter(struct file *fp, struct knote *kn)
2745 badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred)
2754 badfo_close(struct file *fp)
2763 badfo_shutdown(struct file *fp, int how)
2772 nofo_shutdown(struct file *fp, int how)
2774 return (EOPNOTSUPP);
2777 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,
2778 fildesc_drvinit,NULL)