1 /* 2 * descriptor table internals; you almost certainly want file.h instead. 3 */ 4 5 #ifndef __LINUX_FDTABLE_H 6 #define __LINUX_FDTABLE_H 7 8 #include <linux/posix_types.h> 9 #include <linux/compiler.h> 10 #include <linux/spinlock.h> 11 #include <linux/rcupdate.h> 12 #include <linux/types.h> 13 #include <linux/init.h> 14 #include <linux/fs.h> 15 16 #include <linux/atomic.h> 17 18 /* 19 * The default fd array needs to be at least BITS_PER_LONG, 20 * as this is the granularity returned by copy_fdset(). 21 */ 22 #define NR_OPEN_DEFAULT BITS_PER_LONG 23 24 struct fdtable { 25 unsigned int max_fds; 26 struct file __rcu **fd; /* current fd array */ 27 unsigned long *close_on_exec; 28 unsigned long *open_fds; 29 struct rcu_head rcu; 30 struct fdtable *next; 31 }; 32 33 static inline bool close_on_exec(int fd, const struct fdtable *fdt) 34 { 35 return test_bit(fd, fdt->close_on_exec); 36 } 37 38 static inline bool fd_is_open(int fd, const struct fdtable *fdt) 39 { 40 return test_bit(fd, fdt->open_fds); 41 } 42 43 /* 44 * Open file table structure 45 */ 46 struct files_struct { 47 /* 48 * read mostly part 49 */ 50 atomic_t count; 51 struct fdtable __rcu *fdt; 52 struct fdtable fdtab; 53 /* 54 * written part on a separate cache line in SMP 55 */ 56 spinlock_t file_lock ____cacheline_aligned_in_smp; 57 int next_fd; 58 unsigned long close_on_exec_init[1]; 59 unsigned long open_fds_init[1]; 60 struct file __rcu * fd_array[NR_OPEN_DEFAULT]; 61 }; 62 63 #define rcu_dereference_check_fdtable(files, fdtfd) \ 64 (rcu_dereference_check((fdtfd), \ 65 lockdep_is_held(&(files)->file_lock) || \ 66 atomic_read(&(files)->count) == 1 || \ 67 rcu_my_thread_group_empty())) 68 69 #define files_fdtable(files) \ 70 (rcu_dereference_check_fdtable((files), (files)->fdt)) 71 72 struct file_operations; 73 struct vfsmount; 74 struct dentry; 75 76 extern void __init files_defer_init(void); 77 78 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) 79 { 80 struct file * file = NULL; 81 struct fdtable *fdt = files_fdtable(files); 82 83 if (fd < fdt->max_fds) 84 file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); 85 return file; 86 } 87 88 /* 89 * Check whether the specified fd has an open file. 90 */ 91 #define fcheck(fd) fcheck_files(current->files, fd) 92 93 struct task_struct; 94 95 struct files_struct *get_files_struct(struct task_struct *); 96 void put_files_struct(struct files_struct *fs); 97 void reset_files_struct(struct files_struct *); 98 void daemonize_descriptors(void); 99 int unshare_files(struct files_struct **); 100 struct files_struct *dup_fd(struct files_struct *, int *); 101 void do_close_on_exec(struct files_struct *); 102 int iterate_fd(struct files_struct *, unsigned, 103 int (*)(const void *, struct file *, unsigned), 104 const void *); 105 106 extern int __alloc_fd(struct files_struct *files, 107 unsigned start, unsigned end, unsigned flags); 108 extern void __fd_install(struct files_struct *files, 109 unsigned int fd, struct file *file); 110 extern int __close_fd(struct files_struct *files, 111 unsigned int fd); 112 113 extern struct kmem_cache *files_cachep; 114 115 #endif /* __LINUX_FDTABLE_H */ 116