FreeBSD/Linux Kernel Cross Reference
sys/sys/filedesc.h
1 /*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)filedesc.h 8.1 (Berkeley) 6/2/93
30 * $FreeBSD: releng/6.2/sys/sys/filedesc.h 164286 2006-11-14 20:42:41Z cvs2svn $
31 */
32
33 #ifndef _SYS_FILEDESC_H_
34 #define _SYS_FILEDESC_H_
35
36 #include <sys/queue.h>
37 #include <sys/event.h>
38 #include <sys/priority.h>
39 #include <sys/_lock.h>
40 #include <sys/_mutex.h>
41
42 #include <machine/_limits.h>
43
44 /*
45 * This structure is used for the management of descriptors. It may be
46 * shared by multiple processes.
47 */
48 #define NDSLOTTYPE u_long
49
50 struct filedesc {
51 struct file **fd_ofiles; /* file structures for open files */
52 char *fd_ofileflags; /* per-process open file flags */
53 struct vnode *fd_cdir; /* current directory */
54 struct vnode *fd_rdir; /* root directory */
55 struct vnode *fd_jdir; /* jail root directory */
56 int fd_nfiles; /* number of open files allocated */
57 NDSLOTTYPE *fd_map; /* bitmap of free fds */
58 int fd_lastfile; /* high-water mark of fd_ofiles */
59 int fd_freefile; /* approx. next free file */
60 u_short fd_cmask; /* mask for file creation */
61 u_short fd_refcnt; /* thread reference count */
62 u_short fd_holdcnt; /* hold count on structure + mutex */
63
64 struct mtx fd_mtx; /* protects members of this struct */
65 int fd_locked; /* long lock flag */
66 int fd_wanted; /* "" */
67 struct kqlist fd_kqlist; /* list of kqueues on this filedesc */
68 int fd_holdleaderscount; /* block fdfree() for shared close() */
69 int fd_holdleaderswakeup; /* fdfree() needs wakeup */
70 };
71
72 /*
73 * Structure to keep track of (process leader, struct fildedesc) tuples.
74 * Each process has a pointer to such a structure when detailed tracking
75 * is needed, e.g., when rfork(RFPROC | RFMEM) causes a file descriptor
76 * table to be shared by processes having different "p_leader" pointers
77 * and thus distinct POSIX style locks.
78 *
79 * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
80 */
81 struct filedesc_to_leader {
82 int fdl_refcount; /* references from struct proc */
83 int fdl_holdcount; /* temporary hold during closef */
84 int fdl_wakeup; /* fdfree() waits on closef() */
85 struct proc *fdl_leader; /* owner of POSIX locks */
86 /* Circular list: */
87 struct filedesc_to_leader *fdl_prev;
88 struct filedesc_to_leader *fdl_next;
89 };
90
91 /*
92 * Per-process open flags.
93 */
94 #define UF_EXCLOSE 0x01 /* auto-close on exec */
95
96 #ifdef _KERNEL
97
98 /* Lock a file descriptor table. */
99 #define FILEDESC_LOCK(fd) \
100 do { \
101 mtx_lock(&(fd)->fd_mtx); \
102 (fd)->fd_wanted++; \
103 while ((fd)->fd_locked) \
104 msleep(&(fd)->fd_locked, &(fd)->fd_mtx, PLOCK, "fdesc", 0); \
105 (fd)->fd_locked = 2; \
106 (fd)->fd_wanted--; \
107 mtx_unlock(&(fd)->fd_mtx); \
108 } while (0)
109
110 #define FILEDESC_UNLOCK(fd) \
111 do { \
112 mtx_lock(&(fd)->fd_mtx); \
113 KASSERT((fd)->fd_locked == 2, \
114 ("fdesc locking mistake %d should be %d", (fd)->fd_locked, 2)); \
115 (fd)->fd_locked = 0; \
116 if ((fd)->fd_wanted) \
117 wakeup(&(fd)->fd_locked); \
118 mtx_unlock(&(fd)->fd_mtx); \
119 } while (0)
120
121 #define FILEDESC_LOCK_FAST(fd) \
122 do { \
123 mtx_lock(&(fd)->fd_mtx); \
124 (fd)->fd_wanted++; \
125 while ((fd)->fd_locked) \
126 msleep(&(fd)->fd_locked, &(fd)->fd_mtx, PLOCK, "fdesc", 0); \
127 (fd)->fd_locked = 1; \
128 (fd)->fd_wanted--; \
129 } while (0)
130
131 #define FILEDESC_UNLOCK_FAST(fd) \
132 do { \
133 KASSERT((fd)->fd_locked == 1, \
134 ("fdesc locking mistake %d should be %d", (fd)->fd_locked, 1)); \
135 (fd)->fd_locked = 0; \
136 if ((fd)->fd_wanted) \
137 wakeup(&(fd)->fd_locked); \
138 mtx_unlock(&(fd)->fd_mtx); \
139 } while (0)
140
141 #ifdef INVARIANT_SUPPORT
142 #define FILEDESC_LOCK_ASSERT(fd, arg) \
143 do { \
144 if ((arg) == MA_OWNED) \
145 KASSERT((fd)->fd_locked != 0, ("fdesc locking mistake")); \
146 else \
147 KASSERT((fd)->fd_locked == 0, ("fdesc locking mistake")); \
148 } while (0)
149 #else
150 #define FILEDESC_LOCK_ASSERT(fd, arg)
151 #endif
152
153 #define FILEDESC_LOCK_DESC "filedesc structure"
154
155 struct thread;
156
157 int closef(struct file *fp, struct thread *td);
158 int dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd,
159 int mode, int error);
160 int falloc(struct thread *td, struct file **resultfp, int *resultfd);
161 int fdalloc(struct thread *td, int minfd, int *result);
162 int fdavail(struct thread *td, int n);
163 int fdcheckstd(struct thread *td);
164 void fdclose(struct filedesc *fdp, struct file *fp, int idx, struct thread *td);
165 void fdcloseexec(struct thread *td);
166 struct filedesc *fdcopy(struct filedesc *fdp);
167 void fdunshare(struct proc *p, struct thread *td);
168 void fdfree(struct thread *td);
169 struct filedesc *fdinit(struct filedesc *fdp);
170 struct filedesc *fdshare(struct filedesc *fdp);
171 struct filedesc_to_leader *
172 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
173 struct filedesc *fdp, struct proc *leader);
174 int getvnode(struct filedesc *fdp, int fd, struct file **fpp);
175 void mountcheckdirs(struct vnode *olddp, struct vnode *newdp);
176 void setugidsafety(struct thread *td);
177
178 static __inline struct file *
179 fget_locked(struct filedesc *fdp, int fd)
180 {
181
182 return (fd < 0 || fd >= fdp->fd_nfiles ? NULL : fdp->fd_ofiles[fd]);
183 }
184
185 #endif /* _KERNEL */
186
187 #endif /* !_SYS_FILEDESC_H_ */
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