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 struct fdtable *next;
31};
32
33static inline bool close_on_exec(int fd, const struct fdtable *fdt)
34{
35 return test_bit(fd, fdt->close_on_exec);
36}
37
38static inline bool fd_is_open(int fd, const struct fdtable *fdt)
39{
40 return test_bit(fd, fdt->open_fds);
41}
42
43/*
44 * Open file table structure
45 */
46struct files_struct {
47 /*
48 * read mostly part
49 */
50 atomic_t count;
51 struct fdtable __rcu *fdt;
52 struct fdtable fdtab;
53 /*
54 * written part on a separate cache line in SMP
55 */
56 spinlock_t file_lock ____cacheline_aligned_in_smp;
57 int next_fd;
58 unsigned long close_on_exec_init[1];
59 unsigned long open_fds_init[1];
60 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
61};
62
63#define rcu_dereference_check_fdtable(files, fdtfd) \
64 (rcu_dereference_check((fdtfd), \
65 lockdep_is_held(&(files)->file_lock) || \
66 atomic_read(&(files)->count) == 1 || \
67 rcu_my_thread_group_empty()))
68
69#define files_fdtable(files) \
70 (rcu_dereference_check_fdtable((files), (files)->fdt))
71
72struct file_operations;
73struct vfsmount;
74struct dentry;
75
76extern void __init files_defer_init(void);
77
78static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
79{
80 struct file * file = NULL;
81 struct fdtable *fdt = files_fdtable(files);
82
83 if (fd < fdt->max_fds)
84 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
85 return file;
86}
87
88/*
89 * Check whether the specified fd has an open file.
90 */
91#define fcheck(fd) fcheck_files(current->files, fd)
92
93struct task_struct;
94
95struct files_struct *get_files_struct(struct task_struct *);
96void put_files_struct(struct files_struct *fs);
97void reset_files_struct(struct files_struct *);
98void daemonize_descriptors(void);
99int unshare_files(struct files_struct **);
100struct files_struct *dup_fd(struct files_struct *, int *);
101void do_close_on_exec(struct files_struct *);
102int iterate_fd(struct files_struct *, unsigned,
103 int (*)(const void *, struct file *, unsigned),
104 const void *);
105
106extern int __alloc_fd(struct files_struct *files,
107 unsigned start, unsigned end, unsigned flags);
108extern void __fd_install(struct files_struct *files,
109 unsigned int fd, struct file *file);
110extern int __close_fd(struct files_struct *files,
111 unsigned int fd);
112
113extern struct kmem_cache *files_cachep;
114
115#endif /* __LINUX_FDTABLE_H */