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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 | |
24 | struct 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 | |
32 | static inline bool close_on_exec(int fd, const struct fdtable *fdt) |
33 | { |
34 | return test_bit(fd, fdt->close_on_exec); |
35 | } |
36 | |
37 | static 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 | */ |
45 | struct 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 | |
62 | #define rcu_dereference_check_fdtable(files, fdtfd) \ |
63 | (rcu_dereference_check((fdtfd), \ |
64 | lockdep_is_held(&(files)->file_lock) || \ |
65 | atomic_read(&(files)->count) == 1 || \ |
66 | rcu_my_thread_group_empty())) |
67 | |
68 | #define files_fdtable(files) \ |
69 | (rcu_dereference_check_fdtable((files), (files)->fdt)) |
70 | |
71 | struct file_operations; |
72 | struct vfsmount; |
73 | struct dentry; |
74 | |
75 | extern void __init files_defer_init(void); |
76 | |
77 | static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) |
78 | { |
79 | struct file * file = NULL; |
80 | struct fdtable *fdt = files_fdtable(files); |
81 | |
82 | if (fd < fdt->max_fds) |
83 | file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); |
84 | return file; |
85 | } |
86 | |
87 | /* |
88 | * Check whether the specified fd has an open file. |
89 | */ |
90 | #define fcheck(fd) fcheck_files(current->files, fd) |
91 | |
92 | struct task_struct; |
93 | |
94 | struct files_struct *get_files_struct(struct task_struct *); |
95 | void put_files_struct(struct files_struct *fs); |
96 | void reset_files_struct(struct files_struct *); |
97 | int unshare_files(struct files_struct **); |
98 | struct files_struct *dup_fd(struct files_struct *, int *); |
99 | void do_close_on_exec(struct files_struct *); |
100 | int iterate_fd(struct files_struct *, unsigned, |
101 | int (*)(const void *, struct file *, unsigned), |
102 | const void *); |
103 | |
104 | extern int __alloc_fd(struct files_struct *files, |
105 | unsigned start, unsigned end, unsigned flags); |
106 | extern void __fd_install(struct files_struct *files, |
107 | unsigned int fd, struct file *file); |
108 | extern int __close_fd(struct files_struct *files, |
109 | unsigned int fd); |
110 | |
111 | extern struct kmem_cache *files_cachep; |
112 | |
113 | #endif /* __LINUX_FDTABLE_H */ |
114 |
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