include/sysemu/rng.h

   1 /*
   2  * QEMU Random Number Generator Backend
   3  *
   4  * Copyright IBM, Corp. 2012
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #ifndef QEMU_RNG_H
  14 #define QEMU_RNG_H
  15
  16 #include "qom/object.h"
  17 #include "qemu-common.h"
  18
  19 #define TYPE_RNG_BACKEND "rng-backend"
  20 #define RNG_BACKEND(obj) \
  21     OBJECT_CHECK(RngBackend, (obj), TYPE_RNG_BACKEND)
  22 #define RNG_BACKEND_GET_CLASS(obj) \
  23     OBJECT_GET_CLASS(RngBackendClass, (obj), TYPE_RNG_BACKEND)
  24 #define RNG_BACKEND_CLASS(klass) \
  25     OBJECT_CLASS_CHECK(RngBackendClass, (klass), TYPE_RNG_BACKEND)
  26
  27 typedef struct RngRequest RngRequest;
  28 typedef struct RngBackendClass RngBackendClass;
  29 typedef struct RngBackend RngBackend;
  30
  31 typedef void (EntropyReceiveFunc)(void *opaque,
  32                                   const void *data,
  33                                   size_t size);
  34
  35 struct RngRequest
  36 {
  37     EntropyReceiveFunc *receive_entropy;
  38     uint8_t *data;
  39     void *opaque;
  40     size_t offset;
  41     size_t size;
  42 };
  43
  44 struct RngBackendClass
  45 {
  46     ObjectClass parent_class;
  47
  48     void (*request_entropy)(RngBackend *s, size_t size,
  49                             EntropyReceiveFunc *receive_entropy, void *opaque);
  50
  51     void (*opened)(RngBackend *s, Error **errp);
  52 };
  53
  54 struct RngBackend
  55 {
  56     Object parent;
  57
  58     /*< protected >*/
  59     bool opened;
  60     GSList *requests;
  61 };
  62
  63 /**
  64  * rng_backend_request_entropy:
  65  * @s: the backend to request entropy from
  66  * @size: the number of bytes of data to request
  67  * @receive_entropy: a function to be invoked when entropy is available
  68  * @opaque: data that should be passed to @receive_entropy
  69  *
  70  * This function is used by the front-end to request entropy from an entropy
  71  * source.  This function can be called multiple times before @receive_entropy
  72  * is invoked with different values of @receive_entropy and @opaque.  The
  73  * backend will queue each request and handle appropriately.
  74  *
  75  * The backend does not need to pass the full amount of data to @receive_entropy
  76  * but will pass a value greater than 0.
  77  */
  78 void rng_backend_request_entropy(RngBackend *s, size_t size,
  79                                  EntropyReceiveFunc *receive_entropy,
  80                                  void *opaque);
  81 #endif