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 15 struct file; 16 17 extern void fput(struct file *); 18 19 struct file_operations; 20 struct task_struct; 21 struct vfsmount; 22 struct dentry; 23 struct inode; 24 struct path; 25 extern struct file *alloc_file_pseudo(struct inode *, struct vfsmount *, 26 const char *, int flags, const struct file_operations *); 27 extern struct file *alloc_file_pseudo_noaccount(struct inode *, struct vfsmount *, 28 const char *, int flags, const struct file_operations *); 29 extern struct file *alloc_file_clone(struct file *, int flags, 30 const struct file_operations *); 31 32 static inline void fput_light(struct file *file, int fput_needed) 33 { 34 if (fput_needed) 35 fput(file); 36 } 37 38 /* either a reference to struct file + flags 39 * (cloned vs. borrowed, pos locked), with 40 * flags stored in lower bits of value, 41 * or empty (represented by 0). 42 */ 43 struct fd { 44 unsigned long word; 45 }; 46 #define FDPUT_FPUT 1 47 #define FDPUT_POS_UNLOCK 2 48 49 #define fd_file(f) ((struct file *)((f).word & ~(FDPUT_FPUT|FDPUT_POS_UNLOCK))) 50 static inline bool fd_empty(struct fd f) 51 { 52 return unlikely(!f.word); 53 } 54 55 #define EMPTY_FD (struct fd){0} 56 static inline struct fd BORROWED_FD(struct file *f) 57 { 58 return (struct fd){(unsigned long)f}; 59 } 60 static inline struct fd CLONED_FD(struct file *f) 61 { 62 return (struct fd){(unsigned long)f | FDPUT_FPUT}; 63 } 64 65 static inline void fdput(struct fd fd) 66 { 67 if (fd.word & FDPUT_FPUT) 68 fput(fd_file(fd)); 69 } 70 71 extern struct file *fget(unsigned int fd); 72 extern struct file *fget_raw(unsigned int fd); 73 extern struct file *fget_task(struct task_struct *task, unsigned int fd); 74 extern void __f_unlock_pos(struct file *); 75 76 struct fd fdget(unsigned int fd); 77 struct fd fdget_raw(unsigned int fd); 78 struct fd fdget_pos(unsigned int fd); 79 80 static inline void fdput_pos(struct fd f) 81 { 82 if (f.word & FDPUT_POS_UNLOCK) 83 __f_unlock_pos(fd_file(f)); 84 fdput(f); 85 } 86 87 DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd) 88 DEFINE_CLASS(fd_raw, struct fd, fdput(_T), fdget_raw(fd), int fd) 89 90 extern int f_dupfd(unsigned int from, struct file *file, unsigned flags); 91 extern int replace_fd(unsigned fd, struct file *file, unsigned flags); 92 extern void set_close_on_exec(unsigned int fd, int flag); 93 extern bool get_close_on_exec(unsigned int fd); 94 extern int __get_unused_fd_flags(unsigned flags, unsigned long nofile); 95 extern int get_unused_fd_flags(unsigned flags); 96 extern void put_unused_fd(unsigned int fd); 97 98 DEFINE_CLASS(get_unused_fd, int, if (_T >= 0) put_unused_fd(_T), 99 get_unused_fd_flags(flags), unsigned flags) 100 101 /* 102 * take_fd() will take care to set @fd to -EBADF ensuring that 103 * CLASS(get_unused_fd) won't call put_unused_fd(). This makes it 104 * easier to rely on CLASS(get_unused_fd): 105 * 106 * struct file *f; 107 * 108 * CLASS(get_unused_fd, fd)(O_CLOEXEC); 109 * if (fd < 0) 110 * return fd; 111 * 112 * f = dentry_open(&path, O_RDONLY, current_cred()); 113 * if (IS_ERR(f)) 114 * return PTR_ERR(fd); 115 * 116 * fd_install(fd, f); 117 * return take_fd(fd); 118 */ 119 #define take_fd(fd) __get_and_null(fd, -EBADF) 120 121 extern void fd_install(unsigned int fd, struct file *file); 122 123 int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags); 124 125 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags); 126 127 extern void flush_delayed_fput(void); 128 extern void __fput_sync(struct file *); 129 130 extern unsigned int sysctl_nr_open_min, sysctl_nr_open_max; 131 132 #endif /* __LINUX_FILE_H */ 133