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 struct fdtable *next;
31 };
32
__set_close_on_exec(int fd,struct fdtable * fdt)33 static inline void __set_close_on_exec(int fd, struct fdtable *fdt)
34 {
35 __set_bit(fd, fdt->close_on_exec);
36 }
37
__clear_close_on_exec(int fd,struct fdtable * fdt)38 static inline void __clear_close_on_exec(int fd, struct fdtable *fdt)
39 {
40 __clear_bit(fd, fdt->close_on_exec);
41 }
42
close_on_exec(int fd,const struct fdtable * fdt)43 static inline bool close_on_exec(int fd, const struct fdtable *fdt)
44 {
45 return test_bit(fd, fdt->close_on_exec);
46 }
47
__set_open_fd(int fd,struct fdtable * fdt)48 static inline void __set_open_fd(int fd, struct fdtable *fdt)
49 {
50 __set_bit(fd, fdt->open_fds);
51 }
52
__clear_open_fd(int fd,struct fdtable * fdt)53 static inline void __clear_open_fd(int fd, struct fdtable *fdt)
54 {
55 __clear_bit(fd, fdt->open_fds);
56 }
57
fd_is_open(int fd,const struct fdtable * fdt)58 static inline bool fd_is_open(int fd, const struct fdtable *fdt)
59 {
60 return test_bit(fd, fdt->open_fds);
61 }
62
63 /*
64 * Open file table structure
65 */
66 struct files_struct {
67 /*
68 * read mostly part
69 */
70 atomic_t count;
71 struct fdtable __rcu *fdt;
72 struct fdtable fdtab;
73 /*
74 * written part on a separate cache line in SMP
75 */
76 spinlock_t file_lock ____cacheline_aligned_in_smp;
77 int next_fd;
78 unsigned long close_on_exec_init[1];
79 unsigned long open_fds_init[1];
80 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
81 };
82
83 #define rcu_dereference_check_fdtable(files, fdtfd) \
84 (rcu_dereference_check((fdtfd), \
85 lockdep_is_held(&(files)->file_lock) || \
86 atomic_read(&(files)->count) == 1 || \
87 rcu_my_thread_group_empty()))
88
89 #define files_fdtable(files) \
90 (rcu_dereference_check_fdtable((files), (files)->fdt))
91
92 struct file_operations;
93 struct vfsmount;
94 struct dentry;
95
96 extern int expand_files(struct files_struct *, int nr);
97 extern void free_fdtable_rcu(struct rcu_head *rcu);
98 extern void __init files_defer_init(void);
99
free_fdtable(struct fdtable * fdt)100 static inline void free_fdtable(struct fdtable *fdt)
101 {
102 call_rcu(&fdt->rcu, free_fdtable_rcu);
103 }
104
fcheck_files(struct files_struct * files,unsigned int fd)105 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
106 {
107 struct file * file = NULL;
108 struct fdtable *fdt = files_fdtable(files);
109
110 if (fd < fdt->max_fds)
111 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
112 return file;
113 }
114
115 /*
116 * Check whether the specified fd has an open file.
117 */
118 #define fcheck(fd) fcheck_files(current->files, fd)
119
120 struct task_struct;
121
122 struct files_struct *get_files_struct(struct task_struct *);
123 void put_files_struct(struct files_struct *fs);
124 void reset_files_struct(struct files_struct *);
125 int unshare_files(struct files_struct **);
126 struct files_struct *dup_fd(struct files_struct *, int *);
127
128 extern struct kmem_cache *files_cachep;
129
130 #endif /* __LINUX_FDTABLE_H */
131