include/linux/splice.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Function declerations and data structures related to the splice
   4  * implementation.
   5  *
   6  * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
   7  *
   8  */
   9 #ifndef SPLICE_H
  10 #define SPLICE_H
  11
  12 #include <linux/pipe_fs_i.h>
  13
  14 /*
  15  * Flags passed in from splice/tee/vmsplice
  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 #define SPLICE_F_ALL (SPLICE_F_MOVE|SPLICE_F_NONBLOCK|SPLICE_F_MORE|SPLICE_F_GIFT)
  25
  26 /*
  27  * Passed to the actors
  28  */
  29 struct splice_desc {
  30         size_t total_len;               /* remaining length */
  31         unsigned int len;               /* current length */
  32         unsigned int flags;             /* splice flags */
  33         /*
  34          * actor() private data
  35          */
  36         union {
  37                 void __user *userptr;   /* memory to write to */
  38                 struct file *file;      /* file to read/write */
  39                 void *data;             /* cookie */
  40         } u;
  41         void (*splice_eof)(struct splice_desc *sd); /* Unexpected EOF handler */
  42         loff_t pos;                     /* file position */
  43         loff_t *opos;                   /* sendfile: output position */
  44         size_t num_spliced;             /* number of bytes already spliced */
  45         bool need_wakeup;               /* need to wake up writer */
  46 };
  47
  48 struct partial_page {
  49         unsigned int offset;
  50         unsigned int len;
  51         unsigned long private;
  52 };
  53
  54 /*
  55  * Passed to splice_to_pipe
  56  */
  57 struct splice_pipe_desc {
  58         struct page **pages;            /* page map */
  59         struct partial_page *partial;   /* pages[] may not be contig */
  60         int nr_pages;                   /* number of populated pages in map */
  61         unsigned int nr_pages_max;      /* pages[] & partial[] arrays size */
  62         const struct pipe_buf_operations *ops;/* ops associated with output pipe */
  63         void (*spd_release)(struct splice_pipe_desc *, unsigned int);
  64 };
  65
  66 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  67                            struct splice_desc *);
  68 typedef int (splice_direct_actor)(struct pipe_inode_info *,
  69                                   struct splice_desc *);
  70
  71 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  72                                 loff_t *, size_t, unsigned int,
  73                                 splice_actor *);
  74 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
  75                                   struct splice_desc *, splice_actor *);
  76 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
  77                               struct splice_pipe_desc *);
  78 extern ssize_t add_to_pipe(struct pipe_inode_info *,
  79                               struct pipe_buffer *);
  80 long vfs_splice_read(struct file *in, loff_t *ppos,
  81                      struct pipe_inode_info *pipe, size_t len,
  82                      unsigned int flags);
  83 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
  84                                       splice_direct_actor *);
  85 extern long do_splice(struct file *in, loff_t *off_in,
  86                       struct file *out, loff_t *off_out,
  87                       size_t len, unsigned int flags);
  88
  89 extern long do_tee(struct file *in, struct file *out, size_t len,
  90                    unsigned int flags);
  91 extern ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out,
  92                                 loff_t *ppos, size_t len, unsigned int flags);
  93
  94 /*
  95  * for dynamic pipe sizing
  96  */
  97 extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
  98 extern void splice_shrink_spd(struct splice_pipe_desc *);
  99
 100 extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
 101 extern const struct pipe_buf_operations default_pipe_buf_ops;
 102 #endif