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4 * This code is derived from software contributed to The DragonFly Project
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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>
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 int checkfpclosed(struct filedesc *fdp, int fd, struct file *fp);
114 static void ffree(struct file *fp);
116 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table");
117 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader",
118 "file desc to leader structures");
119 MALLOC_DEFINE(M_FILE, "file", "Open file structure");
120 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");
122 static d_open_t fdopen;
125 #define CDEV_MAJOR 22
126 static struct dev_ops fildesc_ops = {
127 { "FD", CDEV_MAJOR, 0 },
132 * Descriptor management.
134 static struct filelist filehead = LIST_HEAD_INITIALIZER(&filehead);
135 static struct spinlock filehead_spin = SPINLOCK_INITIALIZER(&filehead_spin);
136 static int nfiles; /* actual number of open files */
140 * Fixup fd_freefile and fd_lastfile after a descriptor has been cleared.
142 * MPSAFE - must be called with fdp->fd_spin exclusively held
146 fdfixup_locked(struct filedesc *fdp, int fd)
148 if (fd < fdp->fd_freefile) {
149 fdp->fd_freefile = fd;
151 while (fdp->fd_lastfile >= 0 &&
152 fdp->fd_files[fdp->fd_lastfile].fp == NULL &&
153 fdp->fd_files[fdp->fd_lastfile].reserved == 0
160 * System calls on descriptors.
165 sys_getdtablesize(struct getdtablesize_args *uap)
167 struct proc *p = curproc;
168 struct plimit *limit = p->p_limit;
170 spin_lock_rd(&limit->p_spin);
172 min((int)limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc);
173 spin_unlock_rd(&limit->p_spin);
178 * Duplicate a file descriptor to a particular value.
180 * note: keep in mind that a potential race condition exists when closing
181 * descriptors from a shared descriptor table (via rfork).
186 sys_dup2(struct dup2_args *uap)
191 error = kern_dup(DUP_FIXED, uap->from, uap->to, &fd);
192 uap->sysmsg_fds[0] = fd;
198 * Duplicate a file descriptor.
203 sys_dup(struct dup_args *uap)
208 error = kern_dup(DUP_VARIABLE, uap->fd, 0, &fd);
209 uap->sysmsg_fds[0] = fd;
215 * MPALMOSTSAFE - acquires mplock for fp operations
218 kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred)
220 struct thread *td = curthread;
221 struct proc *p = td->td_proc;
227 int tmp, error, flg = F_POSIX;
232 * Operations on file descriptors that do not require a file pointer.
236 error = fgetfdflags(p->p_fd, fd, &tmp);
238 dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0;
242 if (dat->fc_cloexec & FD_CLOEXEC)
243 error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE);
245 error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE);
249 error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd);
256 * Operations on file pointers
258 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
264 dat->fc_flags = OFLAGS(fp->f_flag);
270 nflags = FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS;
271 nflags |= oflags & ~FCNTLFLAGS;
274 if (((nflags ^ oflags) & O_APPEND) && (oflags & FAPPENDONLY))
276 if (error == 0 && ((nflags ^ oflags) & FASYNC)) {
277 tmp = nflags & FASYNC;
278 error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp,
286 error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner,
291 error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner,
297 /* Fall into F_SETLK */
300 if (fp->f_type != DTYPE_VNODE) {
304 vp = (struct vnode *)fp->f_data;
307 * copyin/lockop may block
309 if (dat->fc_flock.l_whence == SEEK_CUR)
310 dat->fc_flock.l_start += fp->f_offset;
312 switch (dat->fc_flock.l_type) {
314 if ((fp->f_flag & FREAD) == 0) {
318 p->p_leader->p_flag |= P_ADVLOCK;
319 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
320 &dat->fc_flock, flg);
323 if ((fp->f_flag & FWRITE) == 0) {
327 p->p_leader->p_flag |= P_ADVLOCK;
328 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
329 &dat->fc_flock, flg);
332 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
333 &dat->fc_flock, F_POSIX);
341 * It is possible to race a close() on the descriptor while
342 * we were blocked getting the lock. If this occurs the
343 * close might not have caught the lock.
345 if (checkfpclosed(p->p_fd, fd, fp)) {
346 dat->fc_flock.l_whence = SEEK_SET;
347 dat->fc_flock.l_start = 0;
348 dat->fc_flock.l_len = 0;
349 dat->fc_flock.l_type = F_UNLCK;
350 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
351 F_UNLCK, &dat->fc_flock, F_POSIX);
356 if (fp->f_type != DTYPE_VNODE) {
360 vp = (struct vnode *)fp->f_data;
362 * copyin/lockop may block
364 if (dat->fc_flock.l_type != F_RDLCK &&
365 dat->fc_flock.l_type != F_WRLCK &&
366 dat->fc_flock.l_type != F_UNLCK) {
370 if (dat->fc_flock.l_whence == SEEK_CUR)
371 dat->fc_flock.l_start += fp->f_offset;
372 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK,
373 &dat->fc_flock, F_POSIX);
386 * The file control system call.
391 sys_fcntl(struct fcntl_args *uap)
398 dat.fc_fd = uap->arg;
401 dat.fc_cloexec = uap->arg;
404 dat.fc_flags = uap->arg;
407 dat.fc_owner = uap->arg;
412 error = copyin((caddr_t)uap->arg, &dat.fc_flock,
413 sizeof(struct flock));
419 error = kern_fcntl(uap->fd, uap->cmd, &dat, curthread->td_ucred);
424 uap->sysmsg_result = dat.fc_fd;
427 uap->sysmsg_result = dat.fc_cloexec;
430 uap->sysmsg_result = dat.fc_flags;
433 uap->sysmsg_result = dat.fc_owner;
435 error = copyout(&dat.fc_flock, (caddr_t)uap->arg,
436 sizeof(struct flock));
445 * Common code for dup, dup2, and fcntl(F_DUPFD).
447 * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells
448 * kern_dup() to destructively dup over an existing file descriptor if new
449 * is already open. DUP_VARIABLE tells kern_dup() to find the lowest
450 * unused file descriptor that is greater than or equal to new.
455 kern_dup(enum dup_type type, int old, int new, int *res)
457 struct thread *td = curthread;
458 struct proc *p = td->td_proc;
459 struct filedesc *fdp = p->p_fd;
467 * Verify that we have a valid descriptor to dup from and
468 * possibly to dup to.
471 spin_lock_wr(&fdp->fd_spin);
472 if (new < 0 || new > p->p_rlimit[RLIMIT_NOFILE].rlim_cur ||
473 new >= maxfilesperproc) {
474 spin_unlock_wr(&fdp->fd_spin);
477 if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) {
478 spin_unlock_wr(&fdp->fd_spin);
481 if (type == DUP_FIXED && old == new) {
483 spin_unlock_wr(&fdp->fd_spin);
486 fp = fdp->fd_files[old].fp;
487 oldflags = fdp->fd_files[old].fileflags;
488 fhold(fp); /* MPSAFE - can be called with a spinlock held */
491 * Allocate a new descriptor if DUP_VARIABLE, or expand the table
492 * if the requested descriptor is beyond the current table size.
494 * This can block. Retry if the source descriptor no longer matches
495 * or if our expectation in the expansion case races.
497 * If we are not expanding or allocating a new decriptor, then reset
498 * the target descriptor to a reserved state so we have a uniform
499 * setup for the next code block.
501 if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) {
502 spin_unlock_wr(&fdp->fd_spin);
503 error = fdalloc(p, new, &newfd);
504 spin_lock_wr(&fdp->fd_spin);
506 spin_unlock_wr(&fdp->fd_spin);
513 if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) {
514 fsetfd_locked(fdp, NULL, newfd);
515 spin_unlock_wr(&fdp->fd_spin);
520 * Check for expansion race
522 if (type != DUP_VARIABLE && new != newfd) {
523 fsetfd_locked(fdp, NULL, newfd);
524 spin_unlock_wr(&fdp->fd_spin);
529 * Check for ripout, newfd reused old (this case probably
533 fsetfd_locked(fdp, NULL, newfd);
534 spin_unlock_wr(&fdp->fd_spin);
541 if (fdp->fd_files[new].reserved) {
542 spin_unlock_wr(&fdp->fd_spin);
544 kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new);
545 tsleep(fdp, 0, "fdres", hz);
550 * If the target descriptor was never allocated we have
551 * to allocate it. If it was we have to clean out the
552 * old descriptor. delfp inherits the ref from the
555 delfp = fdp->fd_files[new].fp;
556 fdp->fd_files[new].fp = NULL;
557 fdp->fd_files[new].reserved = 1;
559 fdreserve_locked(fdp, new, 1);
560 if (new > fdp->fd_lastfile)
561 fdp->fd_lastfile = new;
567 * NOTE: still holding an exclusive spinlock
571 * If a descriptor is being overwritten we may hve to tell
572 * fdfree() to sleep to ensure that all relevant process
573 * leaders can be traversed in closef().
575 if (delfp != NULL && p->p_fdtol != NULL) {
576 fdp->fd_holdleaderscount++;
581 KASSERT(delfp == NULL || type == DUP_FIXED,
582 ("dup() picked an open file"));
585 * Duplicate the source descriptor, update lastfile. If the new
586 * descriptor was not allocated and we aren't replacing an existing
587 * descriptor we have to mark the descriptor as being in use.
589 * The fd_files[] array inherits fp's hold reference.
591 fsetfd_locked(fdp, fp, new);
592 fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE;
593 spin_unlock_wr(&fdp->fd_spin);
598 * If we dup'd over a valid file, we now own the reference to it
599 * and must dispose of it using closef() semantics (as if a
600 * close() were performed on it).
605 spin_lock_wr(&fdp->fd_spin);
606 fdp->fd_holdleaderscount--;
607 if (fdp->fd_holdleaderscount == 0 &&
608 fdp->fd_holdleaderswakeup != 0) {
609 fdp->fd_holdleaderswakeup = 0;
610 spin_unlock_wr(&fdp->fd_spin);
611 wakeup(&fdp->fd_holdleaderscount);
613 spin_unlock_wr(&fdp->fd_spin);
621 * If sigio is on the list associated with a process or process group,
622 * disable signalling from the device, remove sigio from the list and
626 funsetown(struct sigio *sigio)
631 *(sigio->sio_myref) = NULL;
633 if (sigio->sio_pgid < 0) {
634 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
636 } else /* if ((*sigiop)->sio_pgid > 0) */ {
637 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
640 crfree(sigio->sio_ucred);
641 kfree(sigio, M_SIGIO);
644 /* Free a list of sigio structures. */
646 funsetownlst(struct sigiolst *sigiolst)
650 while ((sigio = SLIST_FIRST(sigiolst)) != NULL)
655 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
657 * After permission checking, add a sigio structure to the sigio list for
658 * the process or process group.
661 fsetown(pid_t pgid, struct sigio **sigiop)
677 * Policy - Don't allow a process to FSETOWN a process
678 * in another session.
680 * Remove this test to allow maximum flexibility or
681 * restrict FSETOWN to the current process or process
682 * group for maximum safety.
684 if (proc->p_session != curproc->p_session)
688 } else /* if (pgid < 0) */ {
689 pgrp = pgfind(-pgid);
694 * Policy - Don't allow a process to FSETOWN a process
695 * in another session.
697 * Remove this test to allow maximum flexibility or
698 * restrict FSETOWN to the current process or process
699 * group for maximum safety.
701 if (pgrp->pg_session != curproc->p_session)
707 sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK);
709 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
710 sigio->sio_proc = proc;
712 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
713 sigio->sio_pgrp = pgrp;
715 sigio->sio_pgid = pgid;
716 sigio->sio_ucred = crhold(curthread->td_ucred);
717 /* It would be convenient if p_ruid was in ucred. */
718 sigio->sio_ruid = sigio->sio_ucred->cr_ruid;
719 sigio->sio_myref = sigiop;
727 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
730 fgetown(struct sigio *sigio)
732 return (sigio != NULL ? sigio->sio_pgid : 0);
736 * Close many file descriptors.
741 sys_closefrom(struct closefrom_args *uap)
743 return(kern_closefrom(uap->fd));
747 * Close all file descriptors greater then or equal to fd
752 kern_closefrom(int fd)
754 struct thread *td = curthread;
755 struct proc *p = td->td_proc;
756 struct filedesc *fdp;
765 * NOTE: This function will skip unassociated descriptors and
766 * reserved descriptors that have not yet been assigned.
767 * fd_lastfile can change as a side effect of kern_close().
769 spin_lock_wr(&fdp->fd_spin);
770 while (fd <= fdp->fd_lastfile) {
771 if (fdp->fd_files[fd].fp != NULL) {
772 spin_unlock_wr(&fdp->fd_spin);
773 /* ok if this races another close */
774 if (kern_close(fd) == EINTR)
776 spin_lock_wr(&fdp->fd_spin);
780 spin_unlock_wr(&fdp->fd_spin);
785 * Close a file descriptor.
790 sys_close(struct close_args *uap)
792 return(kern_close(uap->fd));
796 * MPALMOSTSAFE - acquires mplock around knote_fdclose() calls
801 struct thread *td = curthread;
802 struct proc *p = td->td_proc;
803 struct filedesc *fdp;
811 spin_lock_wr(&fdp->fd_spin);
812 if ((fp = funsetfd_locked(fdp, fd)) == NULL) {
813 spin_unlock_wr(&fdp->fd_spin);
817 if (p->p_fdtol != NULL) {
819 * Ask fdfree() to sleep to ensure that all relevant
820 * process leaders can be traversed in closef().
822 fdp->fd_holdleaderscount++;
827 * we now hold the fp reference that used to be owned by the descriptor
830 spin_unlock_wr(&fdp->fd_spin);
831 if (SLIST_FIRST(&fp->f_klist)) {
833 knote_fdclose(fp, fdp, fd);
836 error = closef(fp, p);
838 spin_lock_wr(&fdp->fd_spin);
839 fdp->fd_holdleaderscount--;
840 if (fdp->fd_holdleaderscount == 0 &&
841 fdp->fd_holdleaderswakeup != 0) {
842 fdp->fd_holdleaderswakeup = 0;
843 spin_unlock_wr(&fdp->fd_spin);
844 wakeup(&fdp->fd_holdleaderscount);
846 spin_unlock_wr(&fdp->fd_spin);
853 * shutdown_args(int fd, int how)
856 kern_shutdown(int fd, int how)
858 struct thread *td = curthread;
859 struct proc *p = td->td_proc;
865 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
867 error = fo_shutdown(fp, how);
877 sys_shutdown(struct shutdown_args *uap)
882 error = kern_shutdown(uap->s, uap->how);
892 kern_fstat(int fd, struct stat *ub)
894 struct thread *td = curthread;
895 struct proc *p = td->td_proc;
901 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
903 error = fo_stat(fp, ub, td->td_ucred);
910 * Return status information about a file descriptor.
915 sys_fstat(struct fstat_args *uap)
920 error = kern_fstat(uap->fd, &st);
923 error = copyout(&st, uap->sb, sizeof(st));
928 * 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;
941 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
944 switch (fp->f_type) {
947 if (uap->name != _PC_PIPE_BUF) {
950 uap->sysmsg_result = PIPE_BUF;
956 vp = (struct vnode *)fp->f_data;
958 error = VOP_PATHCONF(vp, uap->name, &uap->sysmsg_reg);
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);
1348 knote_fdclose(fp, fdp, n); /* XXX */
1350 spin_lock_wr(&fdp->fd_spin);
1354 spin_unlock_wr(&fdp->fd_spin);
1355 atomic_subtract_int(&fdp->fd_softrefs, 1);
1361 * Create a new open file structure and reserve a file decriptor
1362 * for the process that refers to it.
1364 * Root creds are checked using lp, or assumed if lp is NULL. If
1365 * resultfd is non-NULL then lp must also be non-NULL. No file
1366 * descriptor is reserved (and no process context is needed) if
1369 * A file pointer with a refcount of 1 is returned. Note that the
1370 * file pointer is NOT associated with the descriptor. If falloc
1371 * returns success, fsetfd() MUST be called to either associate the
1372 * file pointer or clear the reservation.
1377 falloc(struct lwp *lp, struct file **resultfp, int *resultfd)
1379 static struct timeval lastfail;
1382 struct ucred *cred = lp ? lp->lwp_thread->td_ucred : proc0.p_ucred;
1388 * Handle filetable full issues and root overfill.
1390 if (nfiles >= maxfiles - maxfilesrootres &&
1391 (cred->cr_ruid != 0 || nfiles >= maxfiles)) {
1392 if (ppsratecheck(&lastfail, &curfail, 1)) {
1393 kprintf("kern.maxfiles limit exceeded by uid %d, "
1394 "please see tuning(7).\n",
1402 * Allocate a new file descriptor.
1404 fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO);
1405 spin_init(&fp->f_spin);
1406 SLIST_INIT(&fp->f_klist);
1408 fp->f_ops = &badfileops;
1410 fp->f_cred = crhold(cred);
1411 spin_lock_wr(&filehead_spin);
1413 LIST_INSERT_HEAD(&filehead, fp, f_list);
1414 spin_unlock_wr(&filehead_spin);
1416 if ((error = fdalloc(lp->lwp_proc, 0, resultfd)) != 0) {
1433 checkfpclosed(struct filedesc *fdp, int fd, struct file *fp)
1437 spin_lock_rd(&fdp->fd_spin);
1438 if ((unsigned) fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp)
1442 spin_unlock_rd(&fdp->fd_spin);
1447 * Associate a file pointer with a previously reserved file descriptor.
1448 * This function always succeeds.
1450 * If fp is NULL, the file descriptor is returned to the pool.
1454 * MPSAFE (exclusive spinlock must be held on call)
1457 fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd)
1459 KKASSERT((unsigned)fd < fdp->fd_nfiles);
1460 KKASSERT(fdp->fd_files[fd].reserved != 0);
1463 fdp->fd_files[fd].fp = fp;
1464 fdp->fd_files[fd].reserved = 0;
1466 fdp->fd_files[fd].reserved = 0;
1467 fdreserve_locked(fdp, fd, -1);
1468 fdfixup_locked(fdp, fd);
1476 fsetfd(struct filedesc *fdp, struct file *fp, int fd)
1478 spin_lock_wr(&fdp->fd_spin);
1479 fsetfd_locked(fdp, fp, fd);
1480 spin_unlock_wr(&fdp->fd_spin);
1484 * MPSAFE (exclusive spinlock must be held on call)
1488 funsetfd_locked(struct filedesc *fdp, int fd)
1492 if ((unsigned)fd >= fdp->fd_nfiles)
1494 if ((fp = fdp->fd_files[fd].fp) == NULL)
1496 fdp->fd_files[fd].fp = NULL;
1497 fdp->fd_files[fd].fileflags = 0;
1499 fdreserve_locked(fdp, fd, -1);
1500 fdfixup_locked(fdp, fd);
1508 fgetfdflags(struct filedesc *fdp, int fd, int *flagsp)
1512 spin_lock_rd(&fdp->fd_spin);
1513 if (((u_int)fd) >= fdp->fd_nfiles) {
1515 } else if (fdp->fd_files[fd].fp == NULL) {
1518 *flagsp = fdp->fd_files[fd].fileflags;
1521 spin_unlock_rd(&fdp->fd_spin);
1529 fsetfdflags(struct filedesc *fdp, int fd, int add_flags)
1533 spin_lock_wr(&fdp->fd_spin);
1534 if (((u_int)fd) >= fdp->fd_nfiles) {
1536 } else if (fdp->fd_files[fd].fp == NULL) {
1539 fdp->fd_files[fd].fileflags |= add_flags;
1542 spin_unlock_wr(&fdp->fd_spin);
1550 fclrfdflags(struct filedesc *fdp, int fd, int rem_flags)
1554 spin_lock_wr(&fdp->fd_spin);
1555 if (((u_int)fd) >= fdp->fd_nfiles) {
1557 } else if (fdp->fd_files[fd].fp == NULL) {
1560 fdp->fd_files[fd].fileflags &= ~rem_flags;
1563 spin_unlock_wr(&fdp->fd_spin);
1568 fsetcred(struct file *fp, struct ucred *cr)
1576 * Free a file descriptor.
1580 ffree(struct file *fp)
1582 KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!"));
1583 spin_lock_wr(&filehead_spin);
1584 LIST_REMOVE(fp, f_list);
1586 spin_unlock_wr(&filehead_spin);
1588 if (fp->f_nchandle.ncp)
1589 cache_drop(&fp->f_nchandle);
1594 * called from init_main, initialize filedesc0 for proc0.
1597 fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask)
1601 fdp0->fd_refcnt = 1;
1602 fdp0->fd_cmask = cmask;
1603 fdp0->fd_files = fdp0->fd_builtin_files;
1604 fdp0->fd_nfiles = NDFILE;
1605 fdp0->fd_lastfile = -1;
1606 spin_init(&fdp0->fd_spin);
1610 * Build a new filedesc structure.
1615 fdinit(struct proc *p)
1617 struct filedesc *newfdp;
1618 struct filedesc *fdp = p->p_fd;
1620 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO);
1621 spin_lock_rd(&fdp->fd_spin);
1623 newfdp->fd_cdir = fdp->fd_cdir;
1624 vref(newfdp->fd_cdir);
1625 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1629 * rdir may not be set in e.g. proc0 or anything vm_fork'd off of
1630 * proc0, but should unconditionally exist in other processes.
1633 newfdp->fd_rdir = fdp->fd_rdir;
1634 vref(newfdp->fd_rdir);
1635 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1638 newfdp->fd_jdir = fdp->fd_jdir;
1639 vref(newfdp->fd_jdir);
1640 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1642 spin_unlock_rd(&fdp->fd_spin);
1644 /* Create the file descriptor table. */
1645 newfdp->fd_refcnt = 1;
1646 newfdp->fd_cmask = cmask;
1647 newfdp->fd_files = newfdp->fd_builtin_files;
1648 newfdp->fd_nfiles = NDFILE;
1649 newfdp->fd_lastfile = -1;
1650 spin_init(&newfdp->fd_spin);
1656 * Share a filedesc structure.
1661 fdshare(struct proc *p)
1663 struct filedesc *fdp;
1666 spin_lock_wr(&fdp->fd_spin);
1668 spin_unlock_wr(&fdp->fd_spin);
1673 * Copy a filedesc structure.
1678 fdcopy(struct proc *p)
1680 struct filedesc *fdp = p->p_fd;
1681 struct filedesc *newfdp;
1682 struct fdnode *fdnode;
1687 * Certain daemons might not have file descriptors.
1693 * Allocate the new filedesc and fd_files[] array. This can race
1694 * with operations by other threads on the fdp so we have to be
1697 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO);
1699 spin_lock_rd(&fdp->fd_spin);
1700 if (fdp->fd_lastfile < NDFILE) {
1701 newfdp->fd_files = newfdp->fd_builtin_files;
1705 * We have to allocate (N^2-1) entries for our in-place
1706 * binary tree. Allow the table to shrink.
1710 while (ni > fdp->fd_lastfile && ni > NDFILE) {
1714 spin_unlock_rd(&fdp->fd_spin);
1715 newfdp->fd_files = kmalloc(i * sizeof(struct fdnode),
1716 M_FILEDESC, M_WAITOK | M_ZERO);
1719 * Check for race, retry
1721 spin_lock_rd(&fdp->fd_spin);
1722 if (i <= fdp->fd_lastfile) {
1723 spin_unlock_rd(&fdp->fd_spin);
1724 kfree(newfdp->fd_files, M_FILEDESC);
1730 * Dup the remaining fields. vref() and cache_hold() can be
1731 * safely called while holding the read spinlock on fdp.
1733 * The read spinlock on fdp is still being held.
1735 * NOTE: vref and cache_hold calls for the case where the vnode
1736 * or cache entry already has at least one ref may be called
1737 * while holding spin locks.
1739 if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) {
1740 vref(newfdp->fd_cdir);
1741 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1744 * We must check for fd_rdir here, at least for now because
1745 * the init process is created before we have access to the
1746 * rootvode to take a reference to it.
1748 if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) {
1749 vref(newfdp->fd_rdir);
1750 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1752 if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) {
1753 vref(newfdp->fd_jdir);
1754 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1756 newfdp->fd_refcnt = 1;
1757 newfdp->fd_nfiles = i;
1758 newfdp->fd_lastfile = fdp->fd_lastfile;
1759 newfdp->fd_freefile = fdp->fd_freefile;
1760 newfdp->fd_cmask = fdp->fd_cmask;
1761 spin_init(&newfdp->fd_spin);
1764 * Copy the descriptor table through (i). This also copies the
1765 * allocation state. Then go through and ref the file pointers
1766 * and clean up any KQ descriptors.
1768 * kq descriptors cannot be copied. Since we haven't ref'd the
1769 * copied files yet we can ignore the return value from funsetfd().
1771 * The read spinlock on fdp is still being held.
1773 bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode));
1774 for (i = 0 ; i < newfdp->fd_nfiles; ++i) {
1775 fdnode = &newfdp->fd_files[i];
1776 if (fdnode->reserved) {
1777 fdreserve_locked(newfdp, i, -1);
1778 fdnode->reserved = 0;
1779 fdfixup_locked(newfdp, i);
1780 } else if (fdnode->fp) {
1781 if (fdnode->fp->f_type == DTYPE_KQUEUE) {
1782 (void)funsetfd_locked(newfdp, i);
1788 spin_unlock_rd(&fdp->fd_spin);
1793 * Release a filedesc structure.
1795 * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE)
1798 fdfree(struct proc *p, struct filedesc *repl)
1800 struct filedesc *fdp;
1801 struct fdnode *fdnode;
1803 struct filedesc_to_leader *fdtol;
1809 * Certain daemons might not have file descriptors.
1818 * Severe messing around to follow.
1820 spin_lock_wr(&fdp->fd_spin);
1822 /* Check for special need to clear POSIX style locks */
1824 if (fdtol != NULL) {
1825 KASSERT(fdtol->fdl_refcount > 0,
1826 ("filedesc_to_refcount botch: fdl_refcount=%d",
1827 fdtol->fdl_refcount));
1828 if (fdtol->fdl_refcount == 1 &&
1829 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1830 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1831 fdnode = &fdp->fd_files[i];
1832 if (fdnode->fp == NULL ||
1833 fdnode->fp->f_type != DTYPE_VNODE) {
1838 spin_unlock_wr(&fdp->fd_spin);
1840 lf.l_whence = SEEK_SET;
1843 lf.l_type = F_UNLCK;
1844 vp = (struct vnode *)fp->f_data;
1845 (void) VOP_ADVLOCK(vp,
1846 (caddr_t)p->p_leader,
1851 spin_lock_wr(&fdp->fd_spin);
1855 if (fdtol->fdl_refcount == 1) {
1856 if (fdp->fd_holdleaderscount > 0 &&
1857 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1859 * close() or do_dup() has cleared a reference
1860 * in a shared file descriptor table.
1862 fdp->fd_holdleaderswakeup = 1;
1863 ssleep(&fdp->fd_holdleaderscount,
1864 &fdp->fd_spin, 0, "fdlhold", 0);
1867 if (fdtol->fdl_holdcount > 0) {
1869 * Ensure that fdtol->fdl_leader
1870 * remains valid in closef().
1872 fdtol->fdl_wakeup = 1;
1873 ssleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0);
1877 fdtol->fdl_refcount--;
1878 if (fdtol->fdl_refcount == 0 &&
1879 fdtol->fdl_holdcount == 0) {
1880 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev;
1881 fdtol->fdl_prev->fdl_next = fdtol->fdl_next;
1886 if (fdtol != NULL) {
1887 spin_unlock_wr(&fdp->fd_spin);
1888 kfree(fdtol, M_FILEDESC_TO_LEADER);
1889 spin_lock_wr(&fdp->fd_spin);
1892 if (--fdp->fd_refcnt > 0) {
1893 spin_unlock_wr(&fdp->fd_spin);
1894 spin_lock_wr(&p->p_spin);
1896 spin_unlock_wr(&p->p_spin);
1901 * Even though we are the last reference to the structure allproc
1902 * scans may still reference the structure. Maintain proper
1903 * locks until we can replace p->p_fd.
1905 * Also note that kqueue's closef still needs to reference the
1906 * fdp via p->p_fd, so we have to close the descriptors before
1907 * we replace p->p_fd.
1909 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1910 if (fdp->fd_files[i].fp) {
1911 fp = funsetfd_locked(fdp, i);
1913 spin_unlock_wr(&fdp->fd_spin);
1915 spin_lock_wr(&fdp->fd_spin);
1919 spin_unlock_wr(&fdp->fd_spin);
1922 * Interlock against an allproc scan operations (typically frevoke).
1924 spin_lock_wr(&p->p_spin);
1926 spin_unlock_wr(&p->p_spin);
1929 * Wait for any softrefs to go away. This race rarely occurs so
1930 * we can use a non-critical-path style poll/sleep loop. The
1931 * race only occurs against allproc scans.
1933 * No new softrefs can occur with the fdp disconnected from the
1936 if (fdp->fd_softrefs) {
1937 kprintf("pid %d: Warning, fdp race avoided\n", p->p_pid);
1938 while (fdp->fd_softrefs)
1939 tsleep(&fdp->fd_softrefs, 0, "fdsoft", 1);
1942 if (fdp->fd_files != fdp->fd_builtin_files)
1943 kfree(fdp->fd_files, M_FILEDESC);
1945 cache_drop(&fdp->fd_ncdir);
1946 vrele(fdp->fd_cdir);
1949 cache_drop(&fdp->fd_nrdir);
1950 vrele(fdp->fd_rdir);
1953 cache_drop(&fdp->fd_njdir);
1954 vrele(fdp->fd_jdir);
1956 kfree(fdp, M_FILEDESC);
1960 * Retrieve and reference the file pointer associated with a descriptor.
1965 holdfp(struct filedesc *fdp, int fd, int flag)
1969 spin_lock_rd(&fdp->fd_spin);
1970 if (((u_int)fd) >= fdp->fd_nfiles) {
1974 if ((fp = fdp->fd_files[fd].fp) == NULL)
1976 if ((fp->f_flag & flag) == 0 && flag != -1) {
1982 spin_unlock_rd(&fdp->fd_spin);
1987 * holdsock() - load the struct file pointer associated
1988 * with a socket into *fpp. If an error occurs, non-zero
1989 * will be returned and *fpp will be set to NULL.
1994 holdsock(struct filedesc *fdp, int fd, struct file **fpp)
1999 spin_lock_rd(&fdp->fd_spin);
2000 if ((unsigned)fd >= fdp->fd_nfiles) {
2005 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2009 if (fp->f_type != DTYPE_SOCKET) {
2016 spin_unlock_rd(&fdp->fd_spin);
2022 * Convert a user file descriptor to a held file pointer.
2027 holdvnode(struct filedesc *fdp, int fd, struct file **fpp)
2032 spin_lock_rd(&fdp->fd_spin);
2033 if ((unsigned)fd >= fdp->fd_nfiles) {
2038 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2042 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) {
2050 spin_unlock_rd(&fdp->fd_spin);
2056 * For setugid programs, we don't want to people to use that setugidness
2057 * to generate error messages which write to a file which otherwise would
2058 * otherwise be off-limits to the process.
2060 * This is a gross hack to plug the hole. A better solution would involve
2061 * a special vop or other form of generalized access control mechanism. We
2062 * go ahead and just reject all procfs file systems accesses as dangerous.
2064 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is
2065 * sufficient. We also don't for check setugidness since we know we are.
2068 is_unsafe(struct file *fp)
2070 if (fp->f_type == DTYPE_VNODE &&
2071 ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS)
2077 * Make this setguid thing safe, if at all possible.
2079 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2082 setugidsafety(struct proc *p)
2084 struct filedesc *fdp = p->p_fd;
2087 /* Certain daemons might not have file descriptors. */
2092 * note: fdp->fd_files may be reallocated out from under us while
2093 * we are blocked in a close. Be careful!
2095 for (i = 0; i <= fdp->fd_lastfile; i++) {
2098 if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) {
2102 * NULL-out descriptor prior to close to avoid
2103 * a race while close blocks.
2105 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2106 knote_fdclose(fp, fdp, i);
2114 * Close any files on exec?
2116 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2119 fdcloseexec(struct proc *p)
2121 struct filedesc *fdp = p->p_fd;
2124 /* Certain daemons might not have file descriptors. */
2129 * We cannot cache fd_files since operations may block and rip
2130 * them out from under us.
2132 for (i = 0; i <= fdp->fd_lastfile; i++) {
2133 if (fdp->fd_files[i].fp != NULL &&
2134 (fdp->fd_files[i].fileflags & UF_EXCLOSE)) {
2138 * NULL-out descriptor prior to close to avoid
2139 * a race while close blocks.
2141 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2142 knote_fdclose(fp, fdp, i);
2150 * It is unsafe for set[ug]id processes to be started with file
2151 * descriptors 0..2 closed, as these descriptors are given implicit
2152 * significance in the Standard C library. fdcheckstd() will create a
2153 * descriptor referencing /dev/null for each of stdin, stdout, and
2154 * stderr that is not already open.
2156 * NOT MPSAFE - calls falloc, vn_open, etc
2159 fdcheckstd(struct lwp *lp)
2161 struct nlookupdata nd;
2162 struct filedesc *fdp;
2165 int i, error, flags, devnull;
2167 fdp = lp->lwp_proc->p_fd;
2172 for (i = 0; i < 3; i++) {
2173 if (fdp->fd_files[i].fp != NULL)
2176 if ((error = falloc(lp, &fp, &devnull)) != 0)
2179 error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE,
2180 NLC_FOLLOW|NLC_LOCKVP);
2181 flags = FREAD | FWRITE;
2183 error = vn_open(&nd, fp, flags, 0);
2185 fsetfd(fdp, fp, devnull);
2187 fsetfd(fdp, NULL, devnull);
2192 KKASSERT(i == devnull);
2194 error = kern_dup(DUP_FIXED, devnull, i, &retval);
2203 * Internal form of close.
2204 * Decrement reference count on file structure.
2205 * Note: td and/or p may be NULL when closing a file
2206 * that was being passed in a message.
2208 * MPALMOSTSAFE - acquires mplock for VOP operations
2211 closef(struct file *fp, struct proc *p)
2215 struct filedesc_to_leader *fdtol;
2221 * POSIX record locking dictates that any close releases ALL
2222 * locks owned by this process. This is handled by setting
2223 * a flag in the unlock to free ONLY locks obeying POSIX
2224 * semantics, and not to free BSD-style file locks.
2225 * If the descriptor was in a message, POSIX-style locks
2226 * aren't passed with the descriptor.
2228 if (p != NULL && fp->f_type == DTYPE_VNODE &&
2229 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2232 if ((p->p_leader->p_flag & P_ADVLOCK) != 0) {
2233 lf.l_whence = SEEK_SET;
2236 lf.l_type = F_UNLCK;
2237 vp = (struct vnode *)fp->f_data;
2238 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
2242 if (fdtol != NULL) {
2244 * Handle special case where file descriptor table
2245 * is shared between multiple process leaders.
2247 for (fdtol = fdtol->fdl_next;
2248 fdtol != p->p_fdtol;
2249 fdtol = fdtol->fdl_next) {
2250 if ((fdtol->fdl_leader->p_flag &
2253 fdtol->fdl_holdcount++;
2254 lf.l_whence = SEEK_SET;
2257 lf.l_type = F_UNLCK;
2258 vp = (struct vnode *)fp->f_data;
2259 (void) VOP_ADVLOCK(vp,
2260 (caddr_t)fdtol->fdl_leader,
2261 F_UNLCK, &lf, F_POSIX);
2262 fdtol->fdl_holdcount--;
2263 if (fdtol->fdl_holdcount == 0 &&
2264 fdtol->fdl_wakeup != 0) {
2265 fdtol->fdl_wakeup = 0;
2278 * fhold() can only be called if f_count is already at least 1 (i.e. the
2279 * caller of fhold() already has a reference to the file pointer in some
2282 * f_count is not spin-locked. Instead, atomic ops are used for
2283 * incrementing, decrementing, and handling the 1->0 transition.
2286 fhold(struct file *fp)
2288 atomic_add_int(&fp->f_count, 1);
2292 * fdrop() - drop a reference to a descriptor
2294 * MPALMOSTSAFE - acquires mplock for final close sequence
2297 fdrop(struct file *fp)
2304 * A combined fetch and subtract is needed to properly detect
2305 * 1->0 transitions, otherwise two cpus dropping from a ref
2306 * count of 2 might both try to run the 1->0 code.
2308 if (atomic_fetchadd_int(&fp->f_count, -1) > 1)
2314 * The last reference has gone away, we own the fp structure free
2317 if (fp->f_count < 0)
2318 panic("fdrop: count < 0");
2319 if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE &&
2320 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2322 lf.l_whence = SEEK_SET;
2325 lf.l_type = F_UNLCK;
2326 vp = (struct vnode *)fp->f_data;
2327 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2329 if (fp->f_ops != &badfileops)
2330 error = fo_close(fp);
2339 * Apply an advisory lock on a file descriptor.
2341 * Just attempt to get a record lock of the requested type on
2342 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
2347 sys_flock(struct flock_args *uap)
2349 struct proc *p = curproc;
2355 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
2358 if (fp->f_type != DTYPE_VNODE) {
2362 vp = (struct vnode *)fp->f_data;
2363 lf.l_whence = SEEK_SET;
2366 if (uap->how & LOCK_UN) {
2367 lf.l_type = F_UNLCK;
2368 fp->f_flag &= ~FHASLOCK;
2369 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2372 if (uap->how & LOCK_EX)
2373 lf.l_type = F_WRLCK;
2374 else if (uap->how & LOCK_SH)
2375 lf.l_type = F_RDLCK;
2380 fp->f_flag |= FHASLOCK;
2381 if (uap->how & LOCK_NB)
2382 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0);
2384 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT);
2392 * File Descriptor pseudo-device driver (/dev/fd/).
2394 * Opening minor device N dup()s the file (if any) connected to file
2395 * descriptor N belonging to the calling process. Note that this driver
2396 * consists of only the ``open()'' routine, because all subsequent
2397 * references to this file will be direct to the other driver.
2400 fdopen(struct dev_open_args *ap)
2402 thread_t td = curthread;
2404 KKASSERT(td->td_lwp != NULL);
2407 * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the
2408 * the file descriptor being sought for duplication. The error
2409 * return ensures that the vnode for this device will be released
2410 * by vn_open. Open will detect this special error and take the
2411 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
2412 * will simply report the error.
2414 td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev);
2419 * The caller has reserved the file descriptor dfd for us. On success we
2420 * must fsetfd() it. On failure the caller will clean it up.
2425 dupfdopen(struct filedesc *fdp, int dfd, int sfd, int mode, int error)
2431 if ((wfp = holdfp(fdp, sfd, -1)) == NULL)
2435 * Close a revoke/dup race. Duping a descriptor marked as revoked
2436 * will dup a dummy descriptor instead of the real one.
2438 if (wfp->f_flag & FREVOKED) {
2439 kprintf("Warning: attempt to dup() a revoked descriptor\n");
2442 werror = falloc(NULL, &wfp, NULL);
2448 * There are two cases of interest here.
2450 * For ENODEV simply dup sfd to file descriptor dfd and return.
2452 * For ENXIO steal away the file structure from sfd and store it
2453 * dfd. sfd is effectively closed by this operation.
2455 * Any other error code is just returned.
2460 * Check that the mode the file is being opened for is a
2461 * subset of the mode of the existing descriptor.
2463 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
2467 spin_lock_wr(&fdp->fd_spin);
2468 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2469 fsetfd_locked(fdp, wfp, dfd);
2470 spin_unlock_wr(&fdp->fd_spin);
2475 * Steal away the file pointer from dfd, and stuff it into indx.
2477 spin_lock_wr(&fdp->fd_spin);
2478 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2479 fsetfd(fdp, wfp, dfd);
2480 if ((xfp = funsetfd_locked(fdp, sfd)) != NULL) {
2481 spin_unlock_wr(&fdp->fd_spin);
2484 spin_unlock_wr(&fdp->fd_spin);
2496 * NOT MPSAFE - I think these refer to a common file descriptor table
2497 * and we need to spinlock that to link fdtol in.
2499 struct filedesc_to_leader *
2500 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
2501 struct proc *leader)
2503 struct filedesc_to_leader *fdtol;
2505 fdtol = kmalloc(sizeof(struct filedesc_to_leader),
2506 M_FILEDESC_TO_LEADER, M_WAITOK);
2507 fdtol->fdl_refcount = 1;
2508 fdtol->fdl_holdcount = 0;
2509 fdtol->fdl_wakeup = 0;
2510 fdtol->fdl_leader = leader;
2512 fdtol->fdl_next = old->fdl_next;
2513 fdtol->fdl_prev = old;
2514 old->fdl_next = fdtol;
2515 fdtol->fdl_next->fdl_prev = fdtol;
2517 fdtol->fdl_next = fdtol;
2518 fdtol->fdl_prev = fdtol;
2524 * Scan all file pointers in the system. The callback is made with
2525 * the master list spinlock held exclusively.
2530 allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data)
2535 spin_lock_wr(&filehead_spin);
2536 LIST_FOREACH(fp, &filehead, f_list) {
2537 res = callback(fp, data);
2541 spin_unlock_wr(&filehead_spin);
2545 * Get file structures.
2547 * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe)
2550 struct sysctl_kern_file_info {
2553 struct sysctl_req *req;
2556 static int sysctl_kern_file_callback(struct proc *p, void *data);
2559 sysctl_kern_file(SYSCTL_HANDLER_ARGS)
2561 struct sysctl_kern_file_info info;
2564 * Note: because the number of file descriptors is calculated
2565 * in different ways for sizing vs returning the data,
2566 * there is information leakage from the first loop. However,
2567 * it is of a similar order of magnitude to the leakage from
2568 * global system statistics such as kern.openfiles.
2570 * When just doing a count, note that we cannot just count
2571 * the elements and add f_count via the filehead list because
2572 * threaded processes share their descriptor table and f_count might
2573 * still be '1' in that case.
2575 * Since the SYSCTL op can block, we must hold the process to
2576 * prevent it being ripped out from under us either in the
2577 * file descriptor loop or in the greater LIST_FOREACH. The
2578 * process may be in varying states of disrepair. If the process
2579 * is in SZOMB we may have caught it just as it is being removed
2580 * from the allproc list, we must skip it in that case to maintain
2581 * an unbroken chain through the allproc list.
2586 allproc_scan(sysctl_kern_file_callback, &info);
2589 * When just calculating the size, overestimate a bit to try to
2590 * prevent system activity from causing the buffer-fill call
2593 if (req->oldptr == NULL) {
2594 info.count = (info.count + 16) + (info.count / 10);
2595 info.error = SYSCTL_OUT(req, NULL,
2596 info.count * sizeof(struct kinfo_file));
2598 return (info.error);
2602 sysctl_kern_file_callback(struct proc *p, void *data)
2604 struct sysctl_kern_file_info *info = data;
2605 struct kinfo_file kf;
2606 struct filedesc *fdp;
2611 if (p->p_stat == SIDL || p->p_stat == SZOMB)
2613 if (!PRISON_CHECK(info->req->td->td_ucred, p->p_ucred) != 0)
2617 * Softref the fdp to prevent it from being destroyed
2619 spin_lock_wr(&p->p_spin);
2620 if ((fdp = p->p_fd) == NULL) {
2621 spin_unlock_wr(&p->p_spin);
2624 atomic_add_int(&fdp->fd_softrefs, 1);
2625 spin_unlock_wr(&p->p_spin);
2628 * The fdp's own spinlock prevents the contents from being
2631 spin_lock_rd(&fdp->fd_spin);
2632 for (n = 0; n < fdp->fd_nfiles; ++n) {
2633 if ((fp = fdp->fd_files[n].fp) == NULL)
2635 if (info->req->oldptr == NULL) {
2638 uid = p->p_ucred ? p->p_ucred->cr_uid : -1;
2639 kcore_make_file(&kf, fp, p->p_pid, uid, n);
2640 spin_unlock_rd(&fdp->fd_spin);
2641 info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf));
2642 spin_lock_rd(&fdp->fd_spin);
2647 spin_unlock_rd(&fdp->fd_spin);
2648 atomic_subtract_int(&fdp->fd_softrefs, 1);
2654 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
2655 0, 0, sysctl_kern_file, "S,file", "Entire file table");
2657 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
2658 &maxfilesperproc, 0, "Maximum files allowed open per process");
2660 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
2661 &maxfiles, 0, "Maximum number of files");
2663 SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW,
2664 &maxfilesrootres, 0, "Descriptors reserved for root use");
2666 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
2667 &nfiles, 0, "System-wide number of open files");
2670 fildesc_drvinit(void *unused)
2674 for (fd = 0; fd < NUMFDESC; fd++) {
2675 make_dev(&fildesc_ops, fd,
2676 UID_BIN, GID_BIN, 0666, "fd/%d", fd);
2679 make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin");
2680 make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout");
2681 make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr");
2687 struct fileops badfileops = {
2688 .fo_read = badfo_readwrite,
2689 .fo_write = badfo_readwrite,
2690 .fo_ioctl = badfo_ioctl,
2691 .fo_poll = badfo_poll,
2692 .fo_kqfilter = badfo_kqfilter,
2693 .fo_stat = badfo_stat,
2694 .fo_close = badfo_close,
2695 .fo_shutdown = badfo_shutdown
2715 badfo_ioctl(struct file *fp, u_long com, caddr_t data,
2716 struct ucred *cred, struct sysmsg *msgv)
2725 badfo_poll(struct file *fp, int events, struct ucred *cred)
2734 badfo_kqfilter(struct file *fp, struct knote *kn)
2740 badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred)
2749 badfo_close(struct file *fp)
2758 badfo_shutdown(struct file *fp, int how)
2767 nofo_shutdown(struct file *fp, int how)
2769 return (EOPNOTSUPP);
2772 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,
2773 fildesc_drvinit,NULL)