reftable/reftable-blocksource.h

   1 /*
   2 Copyright 2020 Google LLC
   3
   4 Use of this source code is governed by a BSD-style
   5 license that can be found in the LICENSE file or at
   6 https://developers.google.com/open-source/licenses/bsd
   7 */
   8
   9 #ifndef REFTABLE_BLOCKSOURCE_H
  10 #define REFTABLE_BLOCKSOURCE_H
  11
  12 #include <stdint.h>
  13
  14 /* block_source is a generic wrapper for a seekable readable file.
  15  */
  16 struct reftable_block_source {
  17         struct reftable_block_source_vtable *ops;
  18         void *arg;
  19 };
  20
  21 /* a contiguous segment of bytes. It keeps track of its generating block_source
  22  * so it can return itself into the pool. */
  23 struct reftable_block {
  24         uint8_t *data;
  25         int len;
  26         struct reftable_block_source source;
  27 };
  28
  29 /* block_source_vtable are the operations that make up block_source */
  30 struct reftable_block_source_vtable {
  31         /* returns the size of a block source */
  32         uint64_t (*size)(void *source);
  33
  34         /* reads a segment from the block source. It is an error to read
  35            beyond the end of the block */
  36         int (*read_block)(void *source, struct reftable_block *dest,
  37                           uint64_t off, uint32_t size);
  38         /* mark the block as read; may return the data back to malloc */
  39         void (*return_block)(void *source, struct reftable_block *blockp);
  40
  41         /* release all resources associated with the block source */
  42         void (*close)(void *source);
  43 };
  44
  45 /* opens a file on the file system as a block_source */
  46 int reftable_block_source_from_file(struct reftable_block_source *block_src,
  47                                     const char *name);
  48
  49 #endif