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