include/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 #include <stdint.h>
  41
  42 #define NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS     0
  43 #define NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS    1
  44 #define NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS        2
  45 #define NBDKIT_THREAD_MODEL_PARALLEL                  3
  46
  47 struct nbdkit_plugin {
  48   uint64_t _struct_size;
  49   int _api_version;
  50   int _thread_model;
  51
  52   const char *name;
  53   const char *longname;
  54   const char *version;
  55   const char *description;
  56
  57   void (*load) (void);
  58   void (*unload) (void);
  59
  60   int (*config) (const char *key, const char *value);
  61   int (*config_complete) (void);
  62   const char *config_help;
  63
  64   void * (*open) (int readonly);
  65   void (*close) (void *handle);
  66
  67   int64_t (*get_size) (void *handle);
  68
  69   int (*can_write) (void *handle);
  70   int (*can_flush) (void *handle);
  71   int (*is_rotational) (void *handle);
  72   int (*can_trim) (void *handle);
  73
  74   int (*pread) (void *handle, void *buf, uint32_t count, uint64_t offset);
  75   int (*pwrite) (void *handle, const void *buf, uint32_t count, uint64_t offset);
  76   int (*flush) (void *handle);
  77   int (*trim) (void *handle, uint32_t count, uint64_t offset);
  78
  79   /* int (*set_exportname) (void *handle, const char *exportname); */
  80 };
  81
  82 extern void nbdkit_error (const char *msg, ...);
  83 extern void nbdkit_debug (const char *msg, ...);
  84
  85 extern char *nbdkit_absolute_path (const char *path);
  86 extern int64_t nbdkit_parse_size (const char *str);
  87
  88 #define NBDKIT_REGISTER_PLUGIN(plugin)                                  \
  89   struct nbdkit_plugin *                                                \
  90   plugin_init (void)                                                    \
  91   {                                                                     \
  92     (plugin)._struct_size = sizeof (plugin);                            \
  93     (plugin)._api_version = 1;                                          \
  94     (plugin)._thread_model = THREAD_MODEL;                              \
  95     return &(plugin);                                                   \
  96   }
  97
  98 #endif /* NBDKIT_PLUGIN_H */