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))) 45 static inline bool fd_empty(struct fd f) 46 { 47 return unlikely(!f.word); 48 } 49 50 #define EMPTY_FD (struct fd){0} 51 static inline struct fd BORROWED_FD(struct file *f) 52 { 53 return (struct fd){(unsigned long)f}; 54 } 55 static inline struct fd CLONED_FD(struct file *f) 56 { 57 return (struct fd){(unsigned long)f | FDPUT_FPUT}; 58 } 59 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 void __f_unlock_pos(struct file *); 70 71 struct fd fdget(unsigned int fd); 72 struct fd fdget_raw(unsigned int fd); 73 struct fd fdget_pos(unsigned int fd); 74 75 static inline void fdput_pos(struct fd f) 76 { 77 if (f.word & FDPUT_POS_UNLOCK) 78 __f_unlock_pos(fd_file(f)); 79 fdput(f); 80 } 81 82 DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd) 83 DEFINE_CLASS(fd_raw, struct fd, fdput(_T), fdget_raw(fd), int fd) 84 85 extern int f_dupfd(unsigned int from, struct file *file, unsigned flags); 86 extern int replace_fd(unsigned fd, struct file *file, unsigned flags); 87 extern void set_close_on_exec(unsigned int fd, int flag); 88 extern bool get_close_on_exec(unsigned int fd); 89 extern int __get_unused_fd_flags(unsigned flags, unsigned long nofile); 90 extern int get_unused_fd_flags(unsigned flags); 91 extern void put_unused_fd(unsigned int fd); 92 93 DEFINE_CLASS(get_unused_fd, int, if (_T >= 0) put_unused_fd(_T), 94 get_unused_fd_flags(flags), unsigned flags) 95 DEFINE_FREE(fput, struct file *, if (!IS_ERR_OR_NULL(_T)) fput(_T)) 96 97 /* 98 * take_fd() will take care to set @fd to -EBADF ensuring that 99 * CLASS(get_unused_fd) won't call put_unused_fd(). This makes it 100 * easier to rely on CLASS(get_unused_fd): 101 * 102 * struct file *f; 103 * 104 * CLASS(get_unused_fd, fd)(O_CLOEXEC); 105 * if (fd < 0) 106 * return fd; 107 * 108 * f = dentry_open(&path, O_RDONLY, current_cred()); 109 * if (IS_ERR(f)) 110 * return PTR_ERR(f); 111 * 112 * fd_install(fd, f); 113 * return take_fd(fd); 114 */ 115 #define take_fd(fd) __get_and_null(fd, -EBADF) 116 117 extern void fd_install(unsigned int fd, struct file *file); 118 119 int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags); 120 121 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags); 122 123 extern void flush_delayed_fput(void); 124 extern void __fput_sync(struct file *); 125 126 extern unsigned int sysctl_nr_open_min, sysctl_nr_open_max; 127 128 #endif /* __LINUX_FILE_H */ 129