include/linux/file.h

   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
  13 /*
  14  * The default fd array needs to be at least BITS_PER_LONG,
  15  * as this is the granularity returned by copy_fdset().
  16  */
  17 #define NR_OPEN_DEFAULT BITS_PER_LONG
  18
  19 /*
  20  * Open file table structure
  21  */
  22 struct files_struct {
  23         atomic_t count;
  24         spinlock_t file_lock;     /* Protects all the below members.  Nests inside tsk->alloc_lock */
  25         int max_fds;
  26         int max_fdset;
  27         int next_fd;
  28         struct file ** fd;      /* current fd array */
  29         fd_set *close_on_exec;
  30         fd_set *open_fds;
  31         fd_set close_on_exec_init;
  32         fd_set open_fds_init;
  33         struct file * fd_array[NR_OPEN_DEFAULT];
  34 };
  35
  36 extern void FASTCALL(__fput(struct file *));
  37 extern void FASTCALL(fput(struct file *));
  38
  39 static inline void fput_light(struct file *file, int fput_needed)
  40 {
  41         if (unlikely(fput_needed))
  42                 fput(file);
  43 }
  44
  45 extern struct file * FASTCALL(fget(unsigned int fd));
  46 extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
  47 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
  48 extern void put_filp(struct file *);
  49 extern int get_unused_fd(void);
  50 extern void FASTCALL(put_unused_fd(unsigned int fd));
  51 struct kmem_cache_s;
  52 extern void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags);
  53 extern void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags);
  54
  55 extern struct file ** alloc_fd_array(int);
  56 extern void free_fd_array(struct file **, int);
  57
  58 extern fd_set *alloc_fdset(int);
  59 extern void free_fdset(fd_set *, int);
  60
  61 extern int expand_files(struct files_struct *, int nr);
  62
  63 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
  64 {
  65         struct file * file = NULL;
  66
  67         if (fd < files->max_fds)
  68                 file = files->fd[fd];
  69         return file;
  70 }
  71
  72 /*
  73  * Check whether the specified fd has an open file.
  74  */
  75 #define fcheck(fd)      fcheck_files(current->files, fd)
  76
  77 extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
  78
  79 struct task_struct;
  80
  81 struct files_struct *get_files_struct(struct task_struct *);
  82 void FASTCALL(put_files_struct(struct files_struct *fs));
  83
  84 #endif /* __LINUX_FILE_H */