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
fput_light(struct file * file,int fput_needed)33 static inline void fput_light(struct file *file, int fput_needed)
34 {
35 if (fput_needed)
36 fput(file);
37 }
38
39 /* either a reference to struct file + flags
40 * (cloned vs. borrowed, pos locked), with
41 * flags stored in lower bits of value,
42 * or empty (represented by 0).
43 */
44 struct fd {
45 unsigned long word;
46 };
47 #define FDPUT_FPUT 1
48 #define FDPUT_POS_UNLOCK 2
49
50 #define fd_file(f) ((struct file *)((f).word & ~(FDPUT_FPUT|FDPUT_POS_UNLOCK)))
fd_empty(struct fd f)51 static inline bool fd_empty(struct fd f)
52 {
53 return unlikely(!f.word);
54 }
55
56 #define EMPTY_FD (struct fd){0}
BORROWED_FD(struct file * f)57 static inline struct fd BORROWED_FD(struct file *f)
58 {
59 return (struct fd){(unsigned long)f};
60 }
CLONED_FD(struct file * f)61 static inline struct fd CLONED_FD(struct file *f)
62 {
63 return (struct fd){(unsigned long)f | FDPUT_FPUT};
64 }
65
fdput(struct fd fd)66 static inline void fdput(struct fd fd)
67 {
68 if (fd.word & FDPUT_FPUT)
69 fput(fd_file(fd));
70 }
71
72 extern struct file *fget(unsigned int fd);
73 extern struct file *fget_raw(unsigned int fd);
74 extern struct file *fget_task(struct task_struct *task, unsigned int fd);
75 extern void __f_unlock_pos(struct file *);
76
77 struct fd fdget(unsigned int fd);
78 struct fd fdget_raw(unsigned int fd);
79 struct fd fdget_pos(unsigned int fd);
80
fdput_pos(struct fd f)81 static inline void fdput_pos(struct fd f)
82 {
83 if (f.word & FDPUT_POS_UNLOCK)
84 __f_unlock_pos(fd_file(f));
85 fdput(f);
86 }
87
88 DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd)
89 DEFINE_CLASS(fd_raw, struct fd, fdput(_T), fdget_raw(fd), int fd)
90
91 extern int f_dupfd(unsigned int from, struct file *file, unsigned flags);
92 extern int replace_fd(unsigned fd, struct file *file, unsigned flags);
93 extern void set_close_on_exec(unsigned int fd, int flag);
94 extern bool get_close_on_exec(unsigned int fd);
95 extern int __get_unused_fd_flags(unsigned flags, unsigned long nofile);
96 extern int get_unused_fd_flags(unsigned flags);
97 extern void put_unused_fd(unsigned int fd);
98
99 DEFINE_CLASS(get_unused_fd, int, if (_T >= 0) put_unused_fd(_T),
100 get_unused_fd_flags(flags), unsigned flags)
101 DEFINE_FREE(fput, struct file *, if (!IS_ERR_OR_NULL(_T)) fput(_T))
102
103 /*
104 * take_fd() will take care to set @fd to -EBADF ensuring that
105 * CLASS(get_unused_fd) won't call put_unused_fd(). This makes it
106 * easier to rely on CLASS(get_unused_fd):
107 *
108 * struct file *f;
109 *
110 * CLASS(get_unused_fd, fd)(O_CLOEXEC);
111 * if (fd < 0)
112 * return fd;
113 *
114 * f = dentry_open(&path, O_RDONLY, current_cred());
115 * if (IS_ERR(f))
116 * return PTR_ERR(f);
117 *
118 * fd_install(fd, f);
119 * return take_fd(fd);
120 */
121 #define take_fd(fd) __get_and_null(fd, -EBADF)
122
123 extern void fd_install(unsigned int fd, struct file *file);
124
125 int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags);
126
127 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags);
128
129 extern void flush_delayed_fput(void);
130 extern void __fput_sync(struct file *);
131
132 extern unsigned int sysctl_nr_open_min, sysctl_nr_open_max;
133
134 #endif /* __LINUX_FILE_H */
135