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/*
* QEMU Random Number Generator Backend
*
* Copyright IBM, Corp. 2012
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/rng.h"
#include "qemu-char.h"
#include "qerror.h"
#include "hw/qdev.h" /* just for DEFINE_PROP_CHR */
#define TYPE_RNG_EGD "rng-egd"
#define RNG_EGD(obj) OBJECT_CHECK(RngEgd, (obj), TYPE_RNG_EGD)
typedef struct RngEgd
{
RngBackend parent;
CharDriverState *chr;
char *chr_name;
GSList *requests;
} RngEgd;
typedef struct RngRequest
{
EntropyReceiveFunc *receive_entropy;
uint8_t *data;
void *opaque;
size_t offset;
size_t size;
} RngRequest;
static void rng_egd_request_entropy(RngBackend *b, size_t size,
EntropyReceiveFunc *receive_entropy,
void *opaque)
{
RngEgd *s = RNG_EGD(b);
RngRequest *req;
req = g_malloc(sizeof(*req));
req->offset = 0;
req->size = size;
req->receive_entropy = receive_entropy;
req->opaque = opaque;
req->data = g_malloc(req->size);
while (size > 0) {
uint8_t header[2];
uint8_t len = MIN(size, 255);
/* synchronous entropy request */
header[0] = 0x02;
header[1] = len;
qemu_chr_fe_write(s->chr, header, sizeof(header));
size -= len;
}
s->requests = g_slist_append(s->requests, req);
}
static void rng_egd_free_request(RngRequest *req)
{
g_free(req->data);
g_free(req);
}
static int rng_egd_chr_can_read(void *opaque)
{
RngEgd *s = RNG_EGD(opaque);
GSList *i;
int size = 0;
for (i = s->requests; i; i = i->next) {
RngRequest *req = i->data;
size += req->size - req->offset;
}
return size;
}
static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
{
RngEgd *s = RNG_EGD(opaque);
while (size > 0 && s->requests) {
RngRequest *req = s->requests->data;
int len = MIN(size, req->size - req->offset);
memcpy(req->data + req->offset, buf, len);
req->offset += len;
size -= len;
if (req->offset == req->size) {
s->requests = g_slist_remove_link(s->requests, s->requests);
req->receive_entropy(req->opaque, req->data, req->size);
rng_egd_free_request(req);
}
}
}
static void rng_egd_cancel_requests(RngBackend *b)
{
RngEgd *s = RNG_EGD(b);
/* We simply delete the list of pending requests. If there is data in the
* queue waiting to be read, this is okay, because there will always be
* more data than we requested originally
*/
g_slist_free_full(s->requests,
(GDestroyNotify)rng_egd_free_request);
s->requests = NULL;
}
static void rng_egd_opened(RngBackend *b, Error **errp)
{
RngEgd *s = RNG_EGD(b);
if (s->chr_name == NULL) {
error_set(errp, QERR_INVALID_PARAMETER_VALUE,
"chardev", "a valid character device");
return;
}
s->chr = qemu_chr_find(s->chr_name);
if (s->chr == NULL) {
error_set(errp, QERR_DEVICE_NOT_FOUND, s->chr_name);
return;
}
/* FIXME we should resubmit pending requests when the CDS reconnects. */
qemu_chr_add_handlers(s->chr, rng_egd_chr_can_read, rng_egd_chr_read,
NULL, s);
}
static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp)
{
RngBackend *b = RNG_BACKEND(obj);
RngEgd *s = RNG_EGD(b);
if (b->opened) {
error_set(errp, QERR_PERMISSION_DENIED);
} else {
g_free(s->chr_name);
s->chr_name = g_strdup(value);
}
}
static char *rng_egd_get_chardev(Object *obj, Error **errp)
{
RngEgd *s = RNG_EGD(obj);
if (s->chr && s->chr->label) {
return g_strdup(s->chr->label);
}
return NULL;
}
static void rng_egd_init(Object *obj)
{
object_property_add_str(obj, "chardev",
rng_egd_get_chardev, rng_egd_set_chardev,
NULL);
}
static void rng_egd_finalize(Object *obj)
{
RngEgd *s = RNG_EGD(obj);
if (s->chr) {
qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL);
}
g_free(s->chr_name);
g_slist_free_full(s->requests, (GDestroyNotify)rng_egd_free_request);
s->requests = NULL;
}
static void rng_egd_class_init(ObjectClass *klass, void *data)
{
RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
rbc->request_entropy = rng_egd_request_entropy;
rbc->cancel_requests = rng_egd_cancel_requests;
rbc->opened = rng_egd_opened;
}
static TypeInfo rng_egd_info = {
.name = TYPE_RNG_EGD,
.parent = TYPE_RNG_BACKEND,
.instance_size = sizeof(RngEgd),
.class_init = rng_egd_class_init,
.instance_init = rng_egd_init,
.instance_finalize = rng_egd_finalize,
};
static void register_types(void)
{
type_register_static(&rng_egd_info);
}
type_init(register_types);
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