src/nbdkit-plugin.h

   1 /* nbdkit
   2  * Copyright (C) 2013 Red Hat Inc.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met:
   8  *
   9  * * Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *
  12  * * Redistributions in binary form must reproduce the above copyright
  13  * notice, this list of conditions and the following disclaimer in the
  14  * documentation and/or other materials provided with the distribution.
  15  *
  16  * * Neither the name of Red Hat nor the names of its contributors may be
  17  * used to endorse or promote products derived from this software without
  18  * specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  22  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  23  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  25  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  26  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  27  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  28  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  30  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 /* See nbdkit-plugin(3) for documentation and how to write a plugin. */
  35
  36 #ifndef NBDKIT_PLUGIN_H
  37 #define NBDKIT_PLUGIN_H
  38
  39 #include <stdarg.h>
  40
  41 struct nbdkit_plugin {
  42   const char *name;
  43
  44   void (*load) (void);
  45   void (*unload) (void);
  46
  47   void * (*open) (void);
  48   void (*close) (void *handle);
  49
  50   off_t (*get_size) (void *handle);
  51
  52   int (*can_write) (void *handle);
  53   int (*can_flush) (void *handle);
  54   int (*is_rotational) (void *handle);
  55   int (*can_trim) (void *handle);
  56
  57   int (*pread) (void *handle, void *buf, size_t count, off_t offset);
  58   int (*pwrite) (void *handle, const void *buf, size_t count, off_t offset);
  59   int (*flush) (void *handle);
  60   int (*trim) (void *handle, size_t count, off_t offset);
  61
  62   /* int (*set_exportname) (void *handle, const char *exportname); */
  63 };
  64
  65 extern void nbdkit_error (char *msg, ...);
  66
  67 #define NBDKIT_REGISTER_PLUGIN(plugin)                                  \
  68   static struct nbdkit_plugin *plugin_init (size_t *struct_size, int *version) \
  69        __attribute__((constructor));                                    \
  70   static struct nbdkit_plugin *                                         \
  71   plugin_init (size_t *struct_size, int *version)                       \
  72   {                                                                     \
  73     *struct_size = sizeof (plugin);                                     \
  74     *version = 1;                                                       \
  75     return &(plugin);                                                   \
  76   }
  77
  78 #endif /* NBDKIT_PLUGIN_H */