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 struct fdtable {
  20         unsigned int max_fds;
  21         int max_fdset;
  22         int next_fd;
  23         struct file ** fd;      /* current fd array */
  24         fd_set *close_on_exec;
  25         fd_set *open_fds;
  26 };
  27
  28 /*
  29  * Open file table structure
  30  */
  31 struct files_struct {
  32         atomic_t count;
  33         spinlock_t file_lock;     /* Protects all the below members.  Nests inside tsk->alloc_lock */
  34         struct fdtable fdtab;
  35         fd_set close_on_exec_init;
  36         fd_set open_fds_init;
  37         struct file * fd_array[NR_OPEN_DEFAULT];
  38 };
  39
  40 #define files_fdtable(files) (&(files)->fdtab)
  41
  42 extern void FASTCALL(__fput(struct file *));
  43 extern void FASTCALL(fput(struct file *));
  44
  45 static inline void fput_light(struct file *file, int fput_needed)
  46 {
  47         if (unlikely(fput_needed))
  48                 fput(file);
  49 }
  50
  51 extern struct file * FASTCALL(fget(unsigned int fd));
  52 extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
  53 extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
  54 extern void put_filp(struct file *);
  55 extern int get_unused_fd(void);
  56 extern void FASTCALL(put_unused_fd(unsigned int fd));
  57 struct kmem_cache_s;
  58 extern void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags);
  59 extern void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags);
  60
  61 extern struct file ** alloc_fd_array(int);
  62 extern void free_fd_array(struct file **, int);
  63
  64 extern fd_set *alloc_fdset(int);
  65 extern void free_fdset(fd_set *, int);
  66
  67 extern int expand_files(struct files_struct *, int nr);
  68
  69 static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
  70 {
  71         struct file * file = NULL;
  72         struct fdtable *fdt = files_fdtable(files);
  73
  74         if (fd < fdt->max_fds)
  75                 file = fdt->fd[fd];
  76         return file;
  77 }
  78
  79 /*
  80  * Check whether the specified fd has an open file.
  81  */
  82 #define fcheck(fd)      fcheck_files(current->files, fd)
  83
  84 extern void FASTCALL(fd_install(unsigned int fd, struct file * file));
  85
  86 struct task_struct;
  87
  88 struct files_struct *get_files_struct(struct task_struct *);
  89 void FASTCALL(put_files_struct(struct files_struct *fs));
  90
  91 #endif /* __LINUX_FILE_H */