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/nospec.h>
14#include <linux/types.h>
15#include <linux/init.h>
16#include <linux/fs.h>
17
18#include <linux/atomic.h>
19
20/*
21 * The default fd array needs to be at least BITS_PER_LONG,
22 * as this is the granularity returned by copy_fdset().
23 */
24#define NR_OPEN_DEFAULT BITS_PER_LONG
25#define NR_OPEN_MAX ~0U
26
27struct fdtable {
28 unsigned int max_fds;
29 struct file __rcu **fd; /* current fd array */
30 unsigned long *close_on_exec;
31 unsigned long *open_fds;
32 unsigned long *full_fds_bits;
33 struct rcu_head rcu;
34};
35
36static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt)
37{
38 return test_bit(fd, fdt->close_on_exec);
39}
40
41static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt)
42{
43 return test_bit(fd, fdt->open_fds);
44}
45
46/*
47 * Open file table structure
48 */
49struct files_struct {
50 /*
51 * read mostly part
52 */
53 atomic_t count;
54 bool resize_in_progress;
55 wait_queue_head_t resize_wait;
56
57 struct fdtable __rcu *fdt;
58 struct fdtable fdtab;
59 /*
60 * written part on a separate cache line in SMP
61 */
62 spinlock_t file_lock ____cacheline_aligned_in_smp;
63 unsigned int next_fd;
64 unsigned long close_on_exec_init[1];
65 unsigned long open_fds_init[1];
66 unsigned long full_fds_bits_init[1];
67 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
68};
69
70struct file_operations;
71struct vfsmount;
72struct dentry;
73
74#define rcu_dereference_check_fdtable(files, fdtfd) \
75 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
76
77#define files_fdtable(files) \
78 rcu_dereference_check_fdtable((files), (files)->fdt)
79
80/*
81 * The caller must ensure that fd table isn't shared or hold rcu or file lock
82 */
83static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
84{
85 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
86
87 if (fd < fdt->max_fds) {
88 fd = array_index_nospec(fd, fdt->max_fds);
89 return rcu_dereference_raw(fdt->fd[fd]);
90 }
91 return NULL;
92}
93
94static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
95{
96 RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
97 !lockdep_is_held(&files->file_lock),
98 "suspicious rcu_dereference_check() usage");
99 return __fcheck_files(files, fd);
100}
101
102/*
103 * Check whether the specified fd has an open file.
104 */
105#define fcheck(fd) fcheck_files(current->files, fd)
106
107struct task_struct;
108
109struct files_struct *get_files_struct(struct task_struct *);
110void put_files_struct(struct files_struct *fs);
111void reset_files_struct(struct files_struct *);
112int unshare_files(struct files_struct **);
113struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy;
114void do_close_on_exec(struct files_struct *);
115int iterate_fd(struct files_struct *, unsigned,
116 int (*)(const void *, struct file *, unsigned),
117 const void *);
118
119extern int __alloc_fd(struct files_struct *files,
120 unsigned start, unsigned end, unsigned flags);
121extern void __fd_install(struct files_struct *files,
122 unsigned int fd, struct file *file);
123extern int __close_fd(struct files_struct *files,
124 unsigned int fd);
125extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags);
126extern int __close_fd_get_file(unsigned int fd, struct file **res);
127extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
128 struct files_struct **new_fdp);
129
130extern struct kmem_cache *files_cachep;
131
132#endif /* __LINUX_FDTABLE_H */