include/linux/splice.h

   1 /*
   2  * Function declerations and data structures related to the splice
   3  * implementation.
   4  *
   5  * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
   6  *
   7  */
   8 #ifndef SPLICE_H
   9 #define SPLICE_H
  10
  11 #include <linux/pipe_fs_i.h>
  12
  13 /*
  14  * splice is tied to pipes as a transport (at least for now), so we'll just
  15  * add the splice flags here.
  16  */
  17 #define SPLICE_F_MOVE   (0x01)  /* move pages instead of copying */
  18 #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
  19                                  /* we may still block on the fd we splice */
  20                                  /* from/to, of course */
  21 #define SPLICE_F_MORE   (0x04)  /* expect more data */
  22 #define SPLICE_F_GIFT   (0x08)  /* pages passed in are a gift */
  23
  24 /*
  25  * Passed to the actors
  26  */
  27 struct splice_desc {
  28         unsigned int len, total_len;    /* current and remaining length */
  29         unsigned int flags;             /* splice flags */
  30         /*
  31          * actor() private data
  32          */
  33         union {
  34                 void __user *userptr;   /* memory to write to */
  35                 struct file *file;      /* file to read/write */
  36                 void *data;             /* cookie */
  37         } u;
  38         loff_t pos;                     /* file position */
  39 };
  40
  41 struct partial_page {
  42         unsigned int offset;
  43         unsigned int len;
  44         unsigned long private;
  45 };
  46
  47 /*
  48  * Passed to splice_to_pipe
  49  */
  50 struct splice_pipe_desc {
  51         struct page **pages;            /* page map */
  52         struct partial_page *partial;   /* pages[] may not be contig */
  53         int nr_pages;                   /* number of pages in map */
  54         unsigned int flags;             /* splice flags */
  55         const struct pipe_buf_operations *ops;/* ops associated with output pipe */
  56         void (*spd_release)(struct splice_pipe_desc *, unsigned int);
  57 };
  58
  59 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  60                            struct splice_desc *);
  61 typedef int (splice_direct_actor)(struct pipe_inode_info *,
  62                                   struct splice_desc *);
  63
  64 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  65                                 loff_t *, size_t, unsigned int,
  66                                 splice_actor *);
  67 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
  68                                   struct splice_desc *, splice_actor *);
  69 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
  70                               struct splice_pipe_desc *);
  71 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
  72                                       splice_direct_actor *);
  73
  74 #endif