1 /* 2 * Wrapper functions for accessing the file_struct fd array. 3 */ 4 5 #ifndef __LINUX_FILE_H 6 #define __LINUX_FILE_H 7 8 #include <asm/atomic.h> 9 #include <linux/posix_types.h> 10 #include <linux/compiler.h> 11 #include <linux/spinlock.h> 12 #include <linux/rcupdate.h> 13 14 /* 15 * The default fd array needs to be at least BITS_PER_LONG, 16 * as this is the granularity returned by copy_fdset(). 17 */ 18 #define NR_OPEN_DEFAULT BITS_PER_LONG 19 20 struct fdtable { 21 unsigned int max_fds; 22 int max_fdset; 23 int next_fd; 24 struct file ** fd; /* current fd array */ 25 fd_set *close_on_exec; 26 fd_set *open_fds; 27 struct rcu_head rcu; 28 struct files_struct *free_files; 29 struct fdtable *next; 30 }; 31 32 /* 33 * Open file table structure 34 */ 35 struct files_struct { 36 atomic_t count; 37 spinlock_t file_lock; /* Protects all the below members. Nests inside tsk->alloc_lock */ 38 struct fdtable *fdt; 39 struct fdtable fdtab; 40 fd_set close_on_exec_init; 41 fd_set open_fds_init; 42 struct file * fd_array[NR_OPEN_DEFAULT]; 43 }; 44 45 #define files_fdtable(files) (rcu_dereference((files)->fdt)) 46 47 extern void FASTCALL(__fput(struct file *)); 48 extern void FASTCALL(fput(struct file *)); 49 50 static inline void fput_light(struct file *file, int fput_needed) 51 { 52 if (unlikely(fput_needed)) 53 fput(file); 54 } 55 56 extern struct file * FASTCALL(fget(unsigned int fd)); 57 extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed)); 58 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag)); 59 extern void put_filp(struct file *); 60 extern int get_unused_fd(void); 61 extern void FASTCALL(put_unused_fd(unsigned int fd)); 62 struct kmem_cache_s; 63 extern void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags); 64 extern void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags); 65 66 extern struct file ** alloc_fd_array(int); 67 extern void free_fd_array(struct file **, int); 68 69 extern fd_set *alloc_fdset(int); 70 extern void free_fdset(fd_set *, int); 71 72 extern int expand_files(struct files_struct *, int nr); 73 extern void free_fdtable(struct fdtable *fdt); 74 extern void __init files_defer_init(void); 75 76 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) 77 { 78 struct file * file = NULL; 79 struct fdtable *fdt = files_fdtable(files); 80 81 if (fd < fdt->max_fds) 82 file = rcu_dereference(fdt->fd[fd]); 83 return file; 84 } 85 86 /* 87 * Check whether the specified fd has an open file. 88 */ 89 #define fcheck(fd) fcheck_files(current->files, fd) 90 91 extern void FASTCALL(fd_install(unsigned int fd, struct file * file)); 92 93 struct task_struct; 94 95 struct files_struct *get_files_struct(struct task_struct *); 96 void FASTCALL(put_files_struct(struct files_struct *fs)); 97 98 #endif /* __LINUX_FILE_H */ 99