1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Wrapper functions for accessing the file_struct fd array.
4 */
5
6 #ifndef __LINUX_FILE_H
7 #define __LINUX_FILE_H
8
9 #include <linux/compiler.h>
10 #include <linux/types.h>
11 #include <linux/posix_types.h>
12 #include <linux/errno.h>
13 #include <linux/cleanup.h>
14 #include <linux/err.h>
15
16 struct file;
17
18 extern void fput(struct file *);
19
20 struct file_operations;
21 struct task_struct;
22 struct vfsmount;
23 struct dentry;
24 struct inode;
25 struct path;
26 extern struct file *alloc_file_pseudo(struct inode *, struct vfsmount *,
27 const char *, int flags, const struct file_operations *);
28 extern struct file *alloc_file_pseudo_noaccount(struct inode *, struct vfsmount *,
29 const char *, int flags, const struct file_operations *);
30 extern struct file *alloc_file_clone(struct file *, int flags,
31 const struct file_operations *);
32
33 /* either a reference to struct file + flags
34 * (cloned vs. borrowed, pos locked), with
35 * flags stored in lower bits of value,
36 * or empty (represented by 0).
37 */
38 struct fd {
39 unsigned long word;
40 };
41 #define FDPUT_FPUT 1
42 #define FDPUT_POS_UNLOCK 2
43
44 #define fd_file(f) ((struct file *)((f).word & ~(FDPUT_FPUT|FDPUT_POS_UNLOCK)))
fd_empty(struct fd f)45 static inline bool fd_empty(struct fd f)
46 {
47 return unlikely(!f.word);
48 }
49
50 #define EMPTY_FD (struct fd){0}
BORROWED_FD(struct file * f)51 static inline struct fd BORROWED_FD(struct file *f)
52 {
53 return (struct fd){(unsigned long)f};
54 }
CLONED_FD(struct file * f)55 static inline struct fd CLONED_FD(struct file *f)
56 {
57 return (struct fd){(unsigned long)f | FDPUT_FPUT};
58 }
59
fdput(struct fd fd)60 static inline void fdput(struct fd fd)
61 {
62 if (fd.word & FDPUT_FPUT)
63 fput(fd_file(fd));
64 }
65
66 extern struct file *fget(unsigned int fd);
67 extern struct file *fget_raw(unsigned int fd);
68 extern struct file *fget_task(struct task_struct *task, unsigned int fd);
69 extern struct file *fget_task_next(struct task_struct *task, unsigned int *fd);
70 extern void __f_unlock_pos(struct file *);
71
72 struct fd fdget(unsigned int fd);
73 struct fd fdget_raw(unsigned int fd);
74 struct fd fdget_pos(unsigned int fd);
75
fdput_pos(struct fd f)76 static inline void fdput_pos(struct fd f)
77 {
78 if (f.word & FDPUT_POS_UNLOCK)
79 __f_unlock_pos(fd_file(f));
80 fdput(f);
81 }
82
83 DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd)
84 DEFINE_CLASS(fd_raw, struct fd, fdput(_T), fdget_raw(fd), int fd)
85 DEFINE_CLASS(fd_pos, struct fd, fdput_pos(_T), fdget_pos(fd), int fd)
86
87 extern int f_dupfd(unsigned int from, struct file *file, unsigned flags);
88 extern int replace_fd(unsigned fd, struct file *file, unsigned flags);
89 extern void set_close_on_exec(unsigned int fd, int flag);
90 extern bool get_close_on_exec(unsigned int fd);
91 extern int __get_unused_fd_flags(unsigned flags, unsigned long nofile);
92 extern int get_unused_fd_flags(unsigned flags);
93 extern void put_unused_fd(unsigned int fd);
94
95 DEFINE_CLASS(get_unused_fd, int, if (_T >= 0) put_unused_fd(_T),
96 get_unused_fd_flags(flags), unsigned flags)
97 DEFINE_FREE(fput, struct file *, if (!IS_ERR_OR_NULL(_T)) fput(_T))
98
99 /*
100 * take_fd() will take care to set @fd to -EBADF ensuring that
101 * CLASS(get_unused_fd) won't call put_unused_fd(). This makes it
102 * easier to rely on CLASS(get_unused_fd):
103 *
104 * struct file *f;
105 *
106 * CLASS(get_unused_fd, fd)(O_CLOEXEC);
107 * if (fd < 0)
108 * return fd;
109 *
110 * f = dentry_open(&path, O_RDONLY, current_cred());
111 * if (IS_ERR(f))
112 * return PTR_ERR(f);
113 *
114 * fd_install(fd, f);
115 * return take_fd(fd);
116 */
117 #define take_fd(fd) __get_and_null(fd, -EBADF)
118
119 extern void fd_install(unsigned int fd, struct file *file);
120
121 int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags);
122
123 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags);
124
125 extern void flush_delayed_fput(void);
126 extern void __fput_sync(struct file *);
127
128 extern unsigned int sysctl_nr_open_min, sysctl_nr_open_max;
129
130 #endif /* __LINUX_FILE_H */
131