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         rwlock_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 extern struct file * FASTCALL(fget(unsigned int fd));
  39 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
  40 extern void put_filp(struct file *);
  41 extern int get_unused_fd(void);
  42 extern void FASTCALL(put_unused_fd(unsigned int fd));
  43
  44 extern struct file ** alloc_fd_array(int);
  45 extern int expand_fd_array(struct files_struct *, int nr);
  46 extern void free_fd_array(struct file **, int);
  47
  48 extern fd_set *alloc_fdset(int);
  49 extern int expand_fdset(struct files_struct *, int nr);
  50 extern void free_fdset(fd_set *, int);
  51
  52 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
  53 {
  54         struct file * file = NULL;
  55
  56         if (fd < files->max_fds)
  57                 file = files->fd[fd];
  58         return file;
  59 }
  60
  61 /*
  62  * Check whether the specified fd has an open file.
  63  */
  64 #define fcheck(fd)      fcheck_files(current->files, fd)
  65
  66 extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
  67 void FASTCALL(put_files_struct(struct files_struct *fs));
  68
  69 #endif /* __LINUX_FILE_H */