Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * descriptor table internals; you almost certainly want file.h instead.
4 */
5
6#ifndef __LINUX_FDTABLE_H
7#define __LINUX_FDTABLE_H
8
9#include <linux/posix_types.h>
10#include <linux/compiler.h>
11#include <linux/spinlock.h>
12#include <linux/rcupdate.h>
13#include <linux/types.h>
14#include <linux/init.h>
15#include <linux/fs.h>
16
17#include <linux/atomic.h>
18
19/*
20 * The default fd array needs to be at least BITS_PER_LONG,
21 * as this is the granularity returned by copy_fdset().
22 */
23#define NR_OPEN_DEFAULT BITS_PER_LONG
24
25struct fdtable {
26 unsigned int max_fds;
27 struct file __rcu **fd; /* current fd array */
28 unsigned long *close_on_exec;
29 unsigned long *open_fds;
30 unsigned long *full_fds_bits;
31 struct rcu_head rcu;
32};
33
34static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt)
35{
36 return test_bit(fd, fdt->close_on_exec);
37}
38
39static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt)
40{
41 return test_bit(fd, fdt->open_fds);
42}
43
44/*
45 * Open file table structure
46 */
47struct files_struct {
48 /*
49 * read mostly part
50 */
51 atomic_t count;
52 bool resize_in_progress;
53 wait_queue_head_t resize_wait;
54
55 struct fdtable __rcu *fdt;
56 struct fdtable fdtab;
57 /*
58 * written part on a separate cache line in SMP
59 */
60 spinlock_t file_lock ____cacheline_aligned_in_smp;
61 unsigned int next_fd;
62 unsigned long close_on_exec_init[1];
63 unsigned long open_fds_init[1];
64 unsigned long full_fds_bits_init[1];
65 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
66};
67
68struct file_operations;
69struct vfsmount;
70struct dentry;
71
72#define rcu_dereference_check_fdtable(files, fdtfd) \
73 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
74
75#define files_fdtable(files) \
76 rcu_dereference_check_fdtable((files), (files)->fdt)
77
78/*
79 * The caller must ensure that fd table isn't shared or hold rcu or file lock
80 */
81static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
82{
83 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
84
85 if (fd < fdt->max_fds)
86 return rcu_dereference_raw(fdt->fd[fd]);
87 return NULL;
88}
89
90static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
91{
92 RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
93 !lockdep_is_held(&files->file_lock),
94 "suspicious rcu_dereference_check() usage");
95 return __fcheck_files(files, fd);
96}
97
98/*
99 * Check whether the specified fd has an open file.
100 */
101#define fcheck(fd) fcheck_files(current->files, fd)
102
103struct task_struct;
104
105struct files_struct *get_files_struct(struct task_struct *);
106void put_files_struct(struct files_struct *fs);
107void reset_files_struct(struct files_struct *);
108int unshare_files(struct files_struct **);
109struct files_struct *dup_fd(struct files_struct *, int *) __latent_entropy;
110void do_close_on_exec(struct files_struct *);
111int iterate_fd(struct files_struct *, unsigned,
112 int (*)(const void *, struct file *, unsigned),
113 const void *);
114
115extern int __alloc_fd(struct files_struct *files,
116 unsigned start, unsigned end, unsigned flags);
117extern void __fd_install(struct files_struct *files,
118 unsigned int fd, struct file *file);
119extern int __close_fd(struct files_struct *files,
120 unsigned int fd);
121
122extern struct kmem_cache *files_cachep;
123
124#endif /* __LINUX_FDTABLE_H */